Ch 61a Stifle: CCL Flashcards
Bones of the Stifle Joint
- complex condylar synovial joint
- Flexion-extension and rotation are the primary types of motion
- femure: three major articular areas, one each on the medial and lateral femoral condyles (separated by the intercondyloid fossa) and the third within the femoral trochlea on the cranial surface
- fabellae, small sesamoid bones in the tendons of origin of the gastrocnemius muscle
- tibial articular surface is divided into medial and lateral condyles,
- A nonarticular, the intercondylar eminence separates these two articular areas.
- The medial and lateral intercondylar tubercles are atop the eminence > articulate with the femur on their abaxial surfaces
- cranial intercondyloid area > attachment site for the cranial cruciate ligament and the cranial meniscal ligaments
- caudal intercondyloid area > attachment site for the caudal meniscal ligaments.
- popliteal notch, the caudal cruciate ligament attaches to the lateral edge
- The popliteal sesamoid bone is the smallest sesamoid
- The extensor groove at the cranial margin of the lateral tibial condyle > long digital extensor tendon runs through this groove.
- tibial tuberosity> attachment for the patellar ligament, and parts of the biceps femoris and sartorius muscles
Sesamoid Bones of the Stifle Joint
- patella, an ossification in the tendon of insertion of the quadriceps muscle
- base and apex
- articular surface is smooth and convex in all directions
- patella alters the direction of pull of the tendon of the quadriceps femoris muscle (pulley), provides a greater bearing surface for the tendon on the trochlea, and protects the tendon.
- ## articular surface of the stifle joint increased by two or three parapatellar fibrocartilages
Articulations of the Stifle Joint
femorotibial joint
- articulation between the thick, roller-like condyles of the femur and the flattened condyles of the tibia
- the primary weight-bearing articulation.
- The congruity between femoral and tibial condyles is enhanced by the menisc
femoropatellar joint
- improve the efficiency of the extensor mechanism by increasing the moment arm of the quadriceps muscles.
proximal tibiofibular joint
- t
- capsule forms three freely communicating sacs > medial and lateral femorotibial articulations, and the third between the patella and the femur
- fat pad is extrasynovial
- A small synovial bursa is frequently located between the patellar ligament and the tibial tuberosity
Ligaments of the Stifle Joint
medial meniscus
- cranial meniscotibial ligament runs from cranial to attach to the tibia at the cranial intercondyloid area
- caudal meniscotibial ligament runs from caudal to attach to the caudal intercondyloid area of the tibia
lateral meniscus
- cranial meniscotibial ligament attaches to the cranial intercondyloid area of the tibia just caudal to the attachment of the medial
- caudal meniscotibial ligament runs from caudal to attach in the popliteal notch
- meniscofemoral ligament runs from the caudal meniscus to attach within the intercondylar fossa of the femur
intermeniscal ligament
- extends from cranial medial meniscus to the cranial side of the cranial lateral meniscus
Four femorotibial ligaments
- two collateral ligaments and two cruciate ligaments
- cruciate ligaments overed by synovium, they are considered to be extrasynovial
- cruciates ligaments are designated cranial and caudal based on their tibial attachment
- The cruciate ligaments comprise a core region of fascicles containing collagen fibrils and fibroblasts,
- covered by an epiligamentous region composed of synovial intima > absent only where the cranial wraps around the caudal cruciate ligament.
- Abundant mechanoreceptors and proprioreceptors are located within the center of the cruciate ligaments
cranial cruciate ligament
- attaches caudomedial aspect of the lateral femoral condyle and the caudolateral part of the intercondyloid fossa of the femur
- runs diagonally cranially
- attach to the cranial intercondyloid area of the tibia.
- divided into a larger caudolateral band and a smaller craniomedial band
- The craniomedial fibers spiral outward axially approximately 90 degrees
The caudal cruciate ligament
- attaches lateral surface of the medial femoral condyle
- runs caudodistally
- attach to the medial edge of the popliteal notch of the tibia,
- The caudolateral fibers spiral inward abaxially approximately 90 degrees
- larger and longer than the cranial cruciate ligament.
lateral (fibular) collateral ligament
- attaches on the lateral epicondyle of the femur and passes superficial to popliteus muscle
- attached only loosely to the joint capsule
- separated from the lateral meniscus by the tendon of origin of the popliteus
- distal attachment primarily on the head of the fibula
medial (tibial) collateral ligament
- attaches on the medial epicondyle of the femur
- fused with the joint capsule and the medial meniscus (unlike the lateral)
- passes superficial to insertion of the semimembranosus muscle
- attach distally at medial border of the tibial metaphysis
thin medial and lateral femoropatellar ligaments are continuations of the femoral fascia that originate from the sides of the patella.
Meniscus
Shape, Attachment, and Function
- C-shaped disks of fibrocartilage
- shape and roughly triangular cross-section improve joint congruity
- peripheral border of each meniscus is thick, convex, and attached to the inside of the joint capsule
- wedge shape and nearly frictionless surface cause radial extrusive forces to be developed by joint compressive forces.
- The radial force when the joint is weight-loaded is resisted by the tensile stress in the circumferentially arranged collagen fibers
- This tensile stress is referred to as hoop stress
- held in place by ligaments and soft tissue attachments > fundamental for the load distribution function of the menisci because they resist the hoop forces in axial load
- meniscal body is anchored less firmly to the tibia and femur through the coronary ligament
- medial meniscus is firmly attached to the medial collateral ligament and the joint capsule through the coronary ligament that extends along most of the meniscus
- anchorage of the lateral meniscus to the femur and popliteal tendon couple its motion with that of the femoral condyle during rotation > therefore less likely to be injured than the relatively immobile medial meniscus
Composition
The menisci
- primarily composed of an interlacing network of collagen fibers (predominantly type I collagen) interposed with cells and an extracellular matrix of proteoglycans and glycoproteins
- collagen fibrils structured into three layers that allow compressive forces to be dissipated both peripherally and tangentially into hoop stresses > effective mechanism of load sharing
- surface layer: randomly oriented, similarity to articular hyaline cartilage > allow low-friction motion
- innermost third: collagen bundles predominantly lie in a radial pattern
- outer two-thirds: collagen bundles are orientated circumferentially
- suggests that the inner third may function in compression and that the outer in tension.
- Observed less frequently are radially oriented collagen fibers
- proteoglycans, which are large negatively charged hydrophilic molecules > provide the tissue with a high capacity to resist large compressive loads
biphasic theory (Mow et al)
- mechanical behavior of the meniscus under load depends on the solid matrix phase and an interstitial fluid phase.
- when a load is applied, the solid phase (circumferentially oriented collagen bundles) shows an elastic response.
- simultaneously, load is carried by the fluid as it is very slowly extruded
- depends mostly on the extracellular matrix composition, as they increase with increasing glycosaminoglycan content and decrease with increasing water content.
blood supply of the canine meniscus
- originates from vascular layer of the synovium, present on the femoral and tibial surfaces of the meniscus
- These blood vessels supply the peripheral 15% to 25% of the menisci > the red-red zone because of the rich blood supply
- rest of the meniscus is mostly avascular, divided into the axial white-white zone and an intermediate zone called red-white
- perimeniscal capillary plexus, which originates from the medial and lateral genicular arteries
List the sesamoids of the stifle joint
- Patella
- Lateral fabella (larger and more spherical)
- Medial fabella
- Popliteal sesamoid bone (smallest, within tendon of origin of popliteus muscle, articulates with lateral condyle of tibia
List the three articulation of the stifle
Femorotibial
Femoropatellar
Proximal tibiofibular
What are the cruciate ligaments made of?
- Core region of fascicles containing callagen fibrils and fibroblasts
- Covered by an epiligamentous region composed of synovial intima and underlying loose connective tissue (absent where cranial wraps around caudal)
- Abundant mechanorecpetors and proprioceptors in center
What is the composition of the menisci?
- Fibrocartilage, primarily made up of Type I collagen fibers
- Extracellular matrix of proteoglycans and glycoproteins
- Surface layers are randomly orientated for low-friction movement
- Innermost third - radial pattern of collagen
- Outermost 2/3 - circumferential pattern of collagen
- Dispersed radial ‘tie-fibers’ throughout bulk to resist longitudinal splitting
List the differences in the attachments of the medial and lateral menisci
- Medial is firmly attached to medial collateral via the coronary ligament, lateral is not
- Medial is firmly attached to tibia via cranial and caudal meniscotibial ligments. Lateral may or may not have small caudal meniscotibial attachments however it does have a meniscofemoral ligament to the intercondyloid fossa
- Popliteal-meniscal fascicles attach the lateral meniscus to the popliteal tendon
What is the normal range of motion of the stifle?
140 degrees
- flexion 41 deg
- extension 161 deg
Which collateral are taut in flexion and extension?
- Extension: Both are taut (primary stabilisers against rotation) + taut LCL results in external rotation of the tibia
- Flexion: Lateral is loose (thus allows internal rotation of the tibia), medial is taut except for the caudal border
small amount of craniocaudal translation occurs in the sagittal plane during flexion and extension
varsus and valgus angulation
extension
- medial collateral ligament limits valgus
- lateral collateral ligament and the cranial cruciate ligament limit varsus
90 degrees of flexion
- all four femorotibial ligaments limit valgus
- lateral collateral, cranial and caudal cruciate ligaments limit varus
What occurs in response to increased strain in the cranial cruciate ligament?
Contraction of the caudal thigh muscles and relaxation of the quadriceps femoris
- complex system of reflex arcs that involve modulation of the major muscle groups about the stifle by a series of mechanoreceptors and proprioreceptors.
- Joint loading causes increased strain in the cranial cruciate ligament results in simultaneous contraction of the caudal thigh muscles and relaxation of the quadriceps femoris muscle.
cranial cruciate ligament
- primary restraint against cranial tibial translation and hyperextension
- The cranial cruciate ligament and the caudal cruciate ligament twist on themselves to limit internal rotation
- limit varsus in extension, valgus and varsus in flexion
craniomedial band is taut in both flexion and extension
The caudolateral part is taut in extension and lax in flexion
caudal cruciate ligament
- primary restraint against caudal tibial translation
- larger cranial part that is taut in flexion and lax in extension, and a smaller caudal band that is lax in flexion and taut in extension
What are the main functions of the menisci? (4)
Load bearing
Load distribution
Shock absorption
Joint stability
How much of the weight across the stifle do the menisci bear?
40 - 70%
under loading, contact between the femoral condyle and the meniscus increases, and the larger contact area created by the meniscal-articular interface lowers the stress of the articular cartilage of the femur and tibia, protecting against mechanical damage
What is hoop stress?
Compressive forces on the menisci cause the wedge shaped menisci to extrude peripherally, resulting in elongation of the circumferentially orientated collagen fibres due to tensile stress
response of meniscus to loads
- meniscus absorbs energy by undergoing elongation as a load is applied to the knee
- force required to restrain the radial extrusion of the meniscus is derived from the large tensile hoop stress developed within the strong circumferential collagen fiber
- hoop forces are transmitted to the tibia through the cranial and caudal meniscotibial ligaments and the attachment to the medial collateral ligament
- importance of an intact functional unit > Transection of the caudal meniscotibial ligament causes a 140% increase in peak contact pressure and a 50% decrease in contact area.
- hemimeniscectomy cause similar changes
- Removal of the caudal horn causes a focal area of high pressure in the caudal medial tibial condyle
- This alteration of articular cartilage contact pressures is one of the factors contributing to articular cartilage degeneration following meniscectomy
meniscus stability
- contribute to joint stability by increasing the congruity of the femorotibial joint
- meniscus functionally decreases the tibial plateau slope as the prominent caudal horn effectively raises the caudal aspect of the tibial plateau.
- CrCL–deficient stifle joint, caudal pole of the meniscus acts as a wedge, preventing the tibia from further subluxation (primary role in joint stability). This wedge effect increases the risk of meniscal tear in the untreated joint
- normal stifle joint, loss of the meniscus causes minimal translation
- TPLO partially eliminated the wedge effect of the meniscus, suggesting a protective effect of tibial plateau leveling osteotomy against postliminary
- however, TPLO does not protect againts internal-external rotational instability (on;y CrCa translation)
How do various meniscectomies change the joint biomechanics?
- Smaller (30% radial width) partial meniscectomies has minimal effects on biomechanics and function
- Larger (75% radial width) partial meniscectomies and hemimeniscectomies resuted in significant changes in medial and femorotibial contact mechanics
- partial meniscectomies lead to less severe degenerative changes compared to complete
To act as a functional unit, the meniscus needs more than 25% of the radial width of the peripheral tissue
loss of peripheral meniscal tissue eliminates the spacer effect of the meniscus, which is necessary for hoop tension to develop
large body of literature (in vivo) effect of meniscectomy on progression of OA strongly indicates prudent approach to preserve the greatest amount of functional meniscal tissue.
cadavour study
What are the two options of meniscal release?
- Mid-body
- Transection of caudal meniscotibial ligament
No significant differences between the two! Meniscal release is similar to hemimeniscectomy in regards to meniscal function but less radical meniscal excision is associated with less disruption of chondrocytes
Effect of Meniscal Release on Meniscal Function
- goal of eliminating the wedge effect of the caudal horn during femorotibial subluxation. - been investigated in both in vivo and ex vivo experiments
- accepted experimental model in dogs for inducing osteoarthritis
- 50% decrease in contact area + 140% increase in the magnitude of pressure on the medial compartment of a cranial cruciate ligament–deficient stifle joint treated with a tibial plateau leveling osteotomy
- significant caudal shift of load
- supraphysiologic loading of articular cartilage > upregulation in synthesis and degradation of cartilage matrix > OA
- combination of inflammatory and degradative mediators originating from the transected meniscus and biomechanical abnormalities from the loss of hoop tension play key roles
- Meniscal release is equivalent to caudal hemimeniscectomy with regard to meniscal function, further supporting the importance of an intact functional unit
- caudal hemimeniscectomy and total meniscectomy were investigated in vivo: secondary osteoarthritis induced after both types similar in terms of pathologic changes, but the less radical excision is associated with less disruption of chondrocyte metabolism
- Incomplete meniscal regeneration can originate from the synovial membrane but not functional
Kinetics and Kinematics of the Cranial Cruciate Ligament–Deficient Stifle Joint
- abnormal dynamic joint function likely plays a part in OA in CCL-deficient stifles
kinematic
- demonstrated that the CCL–deficient stifle joint remains more flexed throughout the gait cycle.
- hip and tarsocrural joints respond by remaining more extended during the stance phase
- study demonstrated a significantly increased cranial subluxation of the tibia (8 to 12 mm) during the stance phase of the gait. In most, subluxation was unchanged during the swing phase.
- 2 years following, ~ 5 mm of cranial tibial translation was present at the terminal swing phase > The authors suggested intact medial meniscus reducing tibial subluxation as a secondary stabiliser
- long-term joint instability leading to joint capsule fibrosis and meniscal injury may cause a reduction in static joint laxity
- range of abduction and adduction of the stifle joint was nearly doubled at 2 months postoperatively and remained significantly increased at 2 years
kinetic
- analysis has revealed decreases in peak vertical forces and impulses
-
How does CCLR change the peak vertical force?
Normal dogs have PVF of 70% of static BW on limb
After CCLR:
- 25% at 2 weeks
- 32% at 6 weeks
- 37% at 12 weeks
Slocum and Slocum “active model”, 1993
joint stability is maintained by:
1. synergism between the muscle forces responsible for stifle joint flexion and extension
2. cranial tibial thrust force
3. pull of the stifle flexor muscles of the thigh
4. passive restraints of the stifle joint (CCL + caudal pole of the medial meniscus)
two major factors account for the joint compressive force between the tibia and the femur: direct forces of weight bearing and contraction of the gastrocnemius muscle
magnitude of the cranial tibial thrust is dependent on:
1. magnitude of the joint compressive force (weight bearing and counteracted by the active and passive elements)
2. the slope of the tibial plateau
joint reaction force during weight bearing is approximately parallel to the longitudinal axis of the tibia, and it can be resolved into a cranially directed shear force and a joint compressive force (perpendicular to the tibial plateau).
Tibial plateau leveling results in a joint reactive force that is perpendicular to the tibial plateau. Thus, it can only be resolved into a joint compressive force; cranial tibial thrust is eliminated.
Slocum 1993 – active model of the stifle
- tibial compressive force with loading and active force from muscle contraction
- cranial tibial thrust = active force created by weight bearing and muscle
compression of the tibial plateau against the femoral condyles
- balanced by pull of stifle flexor muscles (active), CrCL and caudal horn of
medial meniscus (passive)
- tibial compression created by limb extensors (caudal thigh musculature) and weight
bearing
- magnitude of tibial thrust dependent on amount of compression and slope of tibial
plateau
- increasing tibial plateau slope → increased distance between contact point between
femoral condyle and tibial plateau to axis of compression → larger cranial joint
translation force
- TPLO aims to balance cranial tibial thrust to pull of stifle flexors of the thigh (resisted by
CaCL)
- CaCL strain increased with increasing rotation
The Tepic model, 2002
- total joint force (joint reaction force) is not parallel to the functional axis of the tibia as proposed by Slocum but, instead, is parallel to the patellar ligament
Tepic theorized that under weight-bearing conditions:
1. force applied to the paw is not similar to the moment applied during the tibial compression test (as based in slocum).
2. Instead, force applied to the paw is parallel to the patellar ligament.
3. stabilization procedures should be aimed at leveling the tibial plateau perpendicular to the patellar ligament or altering the angle of the patellar ligament such that it is perpendicular to the tibial plateau
joint reaction force is approximately parallel to the patellar ligament, resolved into a cranially directed shear force and a joint compressive force. Advancing the tibial tuberosity such that the patellar ligament is perpendicular to the tibial plateau neutralizes the cranial tibial thrust force.
theoretical biomechanical models have limitations
- assumptions of both models is full muscle recruitment
- balance between flexor and extensor muscles of the stifle joint may vary between individuals
- TPLO and TTA are two-dimensional, and they do not consider the complex rotational stability of the stifle joint
Cranial Cruciate Ligament Disease
encompass the variety of disorders
- traumatic avulsion of the femoral or tibial attachment
- acute traumatic rupture secondary to excessive strain
- progressive degeneration of unknown cause (partial or complete)
Avulsion of the Cranial Cruciate Ligament
- skeletally immature animals, the attachment of ligament to bone by Sharpey’s fibers may be stronger than the bone
- an acute overload of the ligament, may result in avulsion from tibia, or femur
- may be amenable to primary repair by reattachment (wire, screws)
Epiphysiodesis
- surgically induced premature union of the epiphysis with the diaphysis of the proximal tibia
- to reduce the tibial plateau angle in skeletally immature dogs +/- augment primary repair of an avulsed
- inserted into the center of the cranial intercondyloid area of the tibia and is oriented parallel to the tibial shaft
- Correct placement of the Kirschner wire is confirmed by intraoperative fluoroscopy
- Epiphysiodesis of cranial physis while the caudal aspect continues to grow > reduction of the TPA (as long as residual growth remains)
- case series of 22 joints, a reduction in the tibial plateau angle of 4 degrees and improved or normal gait in 18 of 22
- Valgus deformity in 3 of 22 as the result of eccentric insertion
What procedure can be performed in a skeletally immature dog with CCLR?
What is a potential complication?
Epiphysiodesis
Can cause valgus deformity as a result of eccentric insertion or angulation of the screw
Acute Traumatic Rupture of the Cranial Cruciate Ligament
- Excessive limb loading
- traumatic hyperextension
- excessive internal rotation
- dramatic pain, joint effusion, severe lameness, and stifle joint instability are present.
- injury usually results in a midsubstance “mop end” tear
- RADS: severe effusion with no osteophytes
Progressive Degeneration of the Cranial Cruciate Ligament
- etiopathogenesis of CCL disease,
however; remains incompletely understood. A general consensus is that Abnormal biology and biomechanics interact and exacerbate one another by complex and
largely unknown mechanisms, leading invariably to the development of osteoarthritis - concept of the joint being an organ
is based on the interconnectedness of all tissues including cartilage, synovium, synovial fluid, menisci, cruciate, collateral ligaments and bone - During locomotion, cranial tibial trust seems to exhibit the strongest load which is counteracted by the CCL
- central aspect is poorly vascularized, which often corresponds to area of initial
ligament degeneration and rupture (Hayashi et al 2004) - CCL disease appears to be biphasic with a nearly silent initial phase that involves progressive degradation of the ligament followed by structural failure
- Joint instability then perpetuates inflammatory and degenerative changes in a second phase of secondary OA (Cook 2010).
Biology of CCLR
inflammation, ligament degradation or impaired synthesis of extracellular matrix and early cellular apoptosis.
- some evidence that ligament failure is preceded by relatively silent but progressive collagen matrix degeneration of the intra-articular structures including the CCL (lack of collagen fiber maintenance and loss of fibroblasts from core)
- demonstrated a decrease in material properties with aging.
- The central part of the ligament may be especially vulnerable due to the limited blood supply of this area,
especially once no longer encased by an intact synovium (Hayashi et al 2004).
- Cellular apoptosis has been found in partially ruptured CCL, demonstrating that apoptosis and therefore abnormal ligament tissue is already present in the early stages
- unanswered, however, as to what triggers and perpetuates these
- inflamed synovium also plays an early and significant role in CCL disease
- Kuroki et al (2011) research on synovial histology suggests that the innate immune system plays an important role in initiating and maintaining lymphoplasmacytic synovitis
- Several studies on synovial fluid samples of dogs with CCLR have demonstrated upregulation of enzymes, metabolites, and inflammatory cytokines consistent with
OA including IL-1, IL-6, IL8, and TNFb (de Bruin et al 2007
biomechanics
- instability intuitively plays a key role, other such as anatomic abnormalities, muscle weakness, abnormal kinematics and altered contact areas may precede instability as well as contribute to overall joint inflammation and tissue degeneration (Cook 2010, Kim et al 2009).
- These may be due to underling genetics, nutrition or traumatic events (Cook et al 2020)
- increased strain in the CCL result in simultaneous contraction of the caudal thigh muscles and relaxation of the quadriceps muscle group > protective mechanism, obesity and/or poor physical condition may mitigate these
- correlate factors such as a steep tibial plateau angle conformation, high body weight, breed and neutered status to increased risk of developing CCL disease (Duval et al 1999).
- smaller dogs—those weighing less than 22 kg—tend to be affected later in life than larger dogs
- neutering increases the prevalence of cranial cruciate ligament injury
- variation in the material properties reported bewteem greyhound and rottweiler
- Though evidence for a direct causal link for these risk factors, including for tibial plateau angle, is lacking
- Early osteoarthritic changes are already identifiable in stifle joints with little or no instability, such as in cases of partial rupture (Agnello et al 2021).
- kinematic changes following the functional loss of CCL alter loading of the articular cartilage and result in the development of OA (Griffin and Guilak 2005).
- Second-look arthroscopic evaluation of dogs following TPLO confirm progressive cartilage changes in majority of dogs despite surgery (Hulse et al 2010).
- Intervention in the early stages of CCL disease, i.e. partial rupture, has shown an improved long-term outcome as compared to complete tear (Shimada et al 2020),
List some potential causes of chronic CCLR (4)
- Obesity of poor fitness may mitigate the protective effects of the reflex responses to CCL mechanoreceptors
- Progressive mechanical overload due collagen degeneration (decreased birefringence and elongation of crimping in remaining collagen fibrils)
- Immune-mediated
- Acquired loss of blood supply
TPA
- study: breed and body weight were not significant, whereas age and tibial plateau angle did influence contralateral cranial cruciate ligament rupture, with increasing age being associated with increasing survival of the contralateral ligament.
- another study, tibial plateau angle was not found to be a useful predictor of contralateral rupture in dogs
- no association in labs
breed prevelence
highest
- Rottweiler,
- Newfoundland,
- Staffordshire Terrier
lowest
- Dachshund,
- Basset Hound,
- Old English Sheepdog
before 2 years of age
- Neapolitan Mastiff,
- Akita,
- Saint Bernard,
- Rottweiler,
- Mastiff,
- Newfoundland,
- Chesapeake Bay Retriever,
- Labrador Retriever,
- American Staffordshire Terrier.
Female dogs have an increased prevalence
What percentage of dogs will go on the rupture the CCLR on the contraleteral limb?
22 - 54%
median time of 947 days in one study
physical exam
- Historical findings include pelvic limb lameness that is worse following exercise or periods of rest
- pain response with flexion and extension of the stifle joint, variable crepitus
- quadriceps muscle atrophy
- medial periarticular hypertrophy > medial buttress formation
- Joint effusion
- abnormal “sit test” (Disorders of the hock may also result in this)
cranial drawer test
- creates craniocaudal tibial translation by applying a force to the tibia
- young dogs > physiologic translation (puppy drawer). differentiated from pathologic instability by the sudden stop after 3 to 5 mm of motion.
- severe muscle wasting, a small amount of cranial drawer may be present
partial CCL
- craniomedial band is torn > drawer is present in flexion only because the intact caudolateral part is taut in extension.
- caudolateral part is torn > no cranial drawer is present because the craniomedial band is taut in both flexion and extension
- effusion/pain > likely partial CCL even if no draw
- radiography, magnetic resonance imaging (MRI), and arthroscopy can be used to confirm
tibial compression test
- creates stifle joint compression that results in a cranial tibial thrust force
- if CCL no intact, tibial subluxation occurs
- maintain stifle joint extension
- tarsocrural joint is alternately flexed and extended, simulating contraction of the gastrocnemius
radiography
- osteoarthritis
- confirm stifle pathology in challenging cases of partial tear
- rule out fracture or neoplasia
- loss or effacement of the infrapatellar fat pad shadow by a soft tissue opacity
- osteophyte and/or enthesophyte > femoral trochlear ridges, the tibial condyles, the proximomedial margin of the tibia (collateral ligaments) apex of the patella, narrowing of the intercondylar notch
- subchondral sclerosis
- examination of the contralateral stifle is recommended
- joint effusion and osteophytosis of the contralateral stifle joint were found to be risk factors for rupture of the contralateral
Stifle Joint Arthroscopy
- minimally invasive, low-morbidity
- thorough evaluation of synovium, joint pouches, articular cartilage, cruciate ligaments, and menisci.
- benefits of illumination and magnification,
- allow manipulation of soft tissues such as cruciate ligaments and menisci
- gold standard of joint evaluation: accurate diagnostic tool that enables direct probing and viewing
- In early partial tear, the normal fiber (crimp) pattern is lost and the ligament appears homogeneous, edematous, and palpably lax
- proportion of torn fibers and laxity typically increase as the disease progresses.
- Other findings: synovitis, cartilage fibrillation and eburnation, osteophytosis
What is the sensitivity and specificity of ultrasound for diagnosing meniscal pathology?
non-invasive: MRI and ultrasound
Sensitivtiy 90%
Specificity 92.9%
Meniscal Injury
Epidemiology
- 30-80%
- higher in neutered
- Isolated meniscal tears rare, reported in Boxers and working dogs and also with osteochondral lesions
- medial meniscus
- Radial tears of the lateral meniscus, most commonly tears involving the axial edge of the meniscus (axial fringe tears)
- frequently identified at the time of diagnosis of CCL or later (Postliminary occur after Sx, Latent are present but not identified)
- incidence of postoperative 2.8% to 27.8% > variation due to technique and/or the diagnostic approach
- usually occurs within the first 6 months after surgery, ususally need sx
risk factors
- results of these studies are often contradictory and do not provide enough evidence
- No association with breed, sex, or tibial plateau angle has been found
- increased incidence in overweight dogs and in dogs with chronic and complete ccl
- Most studies report an increased incidence of postoperative meniscal tears in dogs with intact menisci compared to dogs having undergone meniscal release and meniscectomy
- postoperative tears: TTA 3x more likely than dogs treated with TPLO and 6x more likely than dogs treated with TightRope
Meniscal Injury
Etiology, and Pathogenesis
- relates to abnormal motion of CCL–deficient joint
- medial meniscus is firmly attached to the tibia > becomes entrapped between the femoral and tibial condyle during cranial tibial translation
- role as a stabilizer increases its risk of failure
- caudal horn may tear as a result of the shear stress applied to the longitudinal and radial fibers > longitudinal tear
- combination of rotational and translational instability may cause pinching of the cranial pole of the lateral meniscus
- different ligamentous constraints of the medial versus the lateral meniscus likely predispose the medial meniscus to greater risk of injury
surgery that neutralizing joint shear mitigates the wedge effect of the meniscus
- cadaveric study: intact CCL, cranial horn of the medial meniscus experienced the greatest force in extension, the caudal horn when in flexion. Transection of CCL led to a rise in mean force under both horns > Most under the caudal horn of the medial meniscus
- organization of the collagen fibers helps define the type of mechanical failure occurring in the meniscus
- proteoglycans are weaker in both compression and tension than the collagen fibers
- compression of the meniscus produces circumferential tensile stress, the tissue will dissipate strain energy through fissure propagation perpendicular to the tensile stress.
- This mechanism translates into a high incidence of longitudinal tears
What is the reported incidence of meniscal injury in dogs diagnosed with CCLR?
30 - 80%
What is the incidence of lateral meniscal tears in dogs with CCLR?
77% radial tears of the axial edge of the lateral meniscus. Significance unknown
What is the difference between a postliminary meniscal and a latent meniscal tear?
What is the incidence of late meniscal tears (of both kinds combined)
Postliminary - Tears which occur ofter the initial surgery
Latent - Tears which are present at the time of the initial surgery but are not identified
Incidence 2.8 - 27.8deg
The prevalence reflects the number of existing cases of a disease.
In contrast to the prevalence, the incidence reflects the number of new cases of disease and can be reported as a risk or as an incidence rate.
Epidemiology
analysis of the incidence, distribution, and determinants of disease, identifying risk factors
Dx meniscal tear
- Meniscal tears are frequently encountered in cases of chronic cranial cruciate ligament
- postliminary tear occurs, acute lameness may arise
- audible clicking (or both), and pain are suggestive of meniscal tears
- 100% presented with lameness, but only 27% of the dogs had an audible or palpable click.
- sensitivity and specificity of a palpable meniscal click during physical examination were approximately 50% and 90%, respectively, with an overall diagnostic accuracy of 80%
RADs
- limited importance for the diagnosis
- 46% incidence of meniscal mineralization was reported in 100 domestic short- and longhair cats, in the cranial horn of the medial meniscus and severe osteoarthritis
- clinical significance in cats is unknown
conflicting reports have described the benefits of MRI and (CT) arthrography
MRI
- normal meniscus a uniformly low signal on T1-W
- high-field MRI in 11 large-breed, sensitivity of 100% and a specificity of 94%
- sensitivity and specificity of 0.64 and 0.90, respectively, low-field MRI did not reach acceptable levels of diagnostic accuracy
CT
- sensitivity (13% to 73%) and specificity (57% to 100%) for meniscal lesions
- large and displaced meniscal lesions are readily seen on CT arthrography
- Lack of interpreter experience and poor contrast medium distribution in more chronic disease
ultrasound
- prospective study, this noninvasive technique
- high sensitivity and specificity for dogs with severe meniscal tears,
- dependence on operator experience
Surgical Evaluation
- Arthroscopy and arthrotomy
- ex vivo study: Arthroscopy with probe had higher sensitivity and specificity than arthrotomy,
- probing enhanced the sensitivity and specificity for both
- craniomedial arthrotomy was most sensitive in CCL–deficient stifles
- clinical study: probing during arthrotomy is useful for identifying otherwise latent tears
- improved by using a stifle joint distractor
What are some risk factors for developing meniscal tears?
Overweight dogs
Chronic and complete CCLR
TTA 3x more likely vs TPLO
TTA 6x more likely vs Tightrope
What percentage of dogs with meniscal tears will have a palpable or audible meniscal click?
What is the sensitivity and specificty of this test?
27%
- Sensitivty 50%
- Specificity 90%
Dogs with complete CCLR are how much more likely to have a meniscal tear compared to partial CCLR?
9.6 times more likely with a complete tear
What percentage of cats with CCLR will have radiography meniscal mineralisation?
46%
Name the following types of meniscal tears
A: Intact
B: Vertical longitudinal tear (occur parallel to the collagen fibers)
C: Bucket Handle tear (most common, may be seen as multiple tears)
D: Flap or oblique tear
E: Radial tears (from the free inner edge of the meniscus toward the periphery, axial fringe tears)
F: Horizontal tear (difficult to view or probe)
G: Complex tear (in chronic cases and frequently as folded caudal horn)
H: Degenerative tear
How do you achieve the best view of the medial meniscus?
Stifle at 110-130 degrees
External rotation and valgus stress
List the types of meniscectomy (3)
- Caudal hemimeniscectomy (for nonsalvageable injuries of the caudal horn, segmental, from caudal meniscotibial ligament to midbody )
- Total meniscectomy (for tears that extend most of meniscus and an intact rim cannot be preserved or ligamentous attachments are disrupted)
- Partial meniscectomy (removal of damaged axial section while preserving cranial and caudal meniscotibial ligaments and peripheral rim)
cons of menisectomy (3)
Increase in contact stress
a greater degree of osteoarthritis
loss of stability
Meniscal Evaluation
exposure
- Exposure should be optimized using retractors and distraction
- valgus and varus stress are required to view both menisci.
- stable with partial CCLR the caudal pole of the medial meniscus may not be visible with arthrotomy > scope of caudal arthrotomy
- position of the arthroscopy portals is important + appropriate debridement of the fat pad
- portals should be located approximately where the tibial plateau axis intersects the patellar ligament
- causing the tibia to subluxate cranially
- irregularities on the surface and hooking or catching of the probe
- Hooking of the probe at the periphery of the meniscus should be interpreted carefully because the edge of the caudal pole is only loosely attached
Principles of Meniscectomy
arthroscopic meniscectomy modified from Metcalf et al
- arthroscopy provides better magnification and illumination.
- ensure exposure and instrument portal positions are optimal
- risk of iatrogenic articular cartilage damage
- AIM: remove all pathologic tissue while preserving as much normal tissue as possible to maintain meniscal function
- probe is used to progressively evaluate the torn tissue and the extent > axial edge and the meniscal surfaces
- biomechanical function of the meniscus greatly depends on its peripheral tissue. (Loss of hoop stress)
- meniscus-synovium junction should be preserved
- Motorized shavers of small diameter (≤3.5- 2.5-mm in medium-size and larger dogs)
- Resection of unstable meniscal fragments is important to prevent entrapment
- piecemeal removal or en bloc resection
- removed using suction, or they are flushed from the joint
- punch, meniscal knife, beaver blade or Motorized shavers
Meniscal Release
- advocated in conjunction with TPLO to prevent the development of postoperative meniscal injuries
- caudal meniscotibial ligament of the medial meniscus (caudal release) or at the midbody of the medial meniscus (central release)
- Meniscal release allows the caudal horn of the medial meniscus to displace caudally, avoiding impingement
- postoperative meniscal injuries are more likely caused by persistent instability (rotational or translational) or misdiagnosis
- MRI STUDY: spared the caudal horn from entrapment and confirmed caudolateral displacement of the caudal horn after both types of meniscal release. suggest that releasing the meniscus should completely eliminate the risk of a postliminary injury.
- late meniscal injury has been documented to occur despite meniscal release in some patients (dt poor technique or atent tear that progresses to a degenerated meniscus)
mid body release
- inside-to-outside or an outside-to-inside technique
- caudal edge of the medial collateral ligament
- 30 degree angle
- confirm complete release with a probe
caudal release
Clinical Outcome and Decision Making for Meniscal Treatment
- meniscal treatment is performed with a stabilization technique > Therefore difficult to isolate the clinical effects of meniscal treatment from those of the stabilization procedure
postliminary meniscal tears,
- the outcome after meniscectomy is excellent in the short term
- 88% improvement, or return to normal status
meniscectomy
- prospective study: type of treatment of the meniscus may have a greater impact on clinical outcome than does the cranial cruciate ligament stabilization technique. Dogs diagnosed and treated for concurrent (i.e., tears identified during the original surgery) meniscal tears were 1.3 times more likely to have a successful long-term outcome than cases in which a concurrent tear was not identified
- effect in the long term may be less favorable because of the progression of osteoarthritis
- STUDY Innes: 50 months after surgery, dogs that had meniscal injury had higher scores for disability, inactivity, and stiffness than those without a meniscal injury
- time to follow-up is a major factor in outcome after meniscectomy; Other studies suggest minimal difference in the short term after meniscectomy
- conserving functional meniscal tissue is advantageous in the long term.
- Innes and others provided good evidence that an intact meniscus plays a major role in the long-term function of dogs operated for cranial cruciate ligament insufficiency
- conservative treatment is crucial for the lateral meniscus
meniscal release
- Short-term have been reported, but no long-term outcome studies
- justified when the incidence of postliminary tears is unacceptably high
- Because release is not always effective in preventing postliminary tears, caudal hemimeniscectomy may be a better to completely eliminate the risk
- meniscal release is functionally equivalent to a caudal hemimeniscectomy > speculated may be a poor prognostic factor in the long term
- available data support the use of meniscal release in conjunction with stabilization procedures with a high rate of postliminary meniscal injury, or when the prospect of a revision surgery is not acceptable for the owner.
best strategy to decrease latent tears is to improve the accuracy of meniscal diagnosis
- 4x more likely to occur in dogs treated by arthrotomy with no meniscal release than in dogs treated with arthroscopy with no meniscal release
- Meniscal diagnosis can be improved by probing, magnification, illumination, retraction, and distraction
- high rate of true postliminary meniscal tears may result from a stabilization technique (choose a Sx that protects meniscus best)
- argued that the meniscus should be preserved at any cost, despite the risk of reoperation
Repair of the meniscus
- reported but the lack of outcome data difficult to provide clinical guidelines
- Meniscal repair is limited to those tears located in the red-red (most peripheral) region of the meniscus
Lateral Fabellotibial Suture
- techniques rely on periarticular fibrosis for long-term stability because the stability first created is relatively short lived
- modification of the extracapsular technique reported by DeAngelis and Lau
- lateral arthrotomy, assess intra-articular
- damaged cranial cruciate ligament are removed because they may act as a source of continued inflammation (not proven)
- joint is copiously lavaged with physiologic saline
- craniodistal aspect of the lateral fabella articulates with the femur > suture placed slightly proximal to the fabella, in fibrous origin of lateral gastrocnemius muscle
- proximal end of the tibia is exposed by incising the fascia overlying the cranial tibial muscle; one or two holes are drilled
- limb is positioned at approximately 100 degrees of flexion
- suture is tensioned adequately to neutralize the cranial drawer; it is not overtightened (decreased ROM and increased contact pressure in the joint)
- stability is confirmed by a negative cranial drawer test and a negative tibial compression test
- Mayo mattress pattern (vest over pants) or with another imbrication
- echeck examination to assess stifle joint stability and limb use is performed 6 to 8 weeks
- normal activity is encouraged during weeks 9 to 16 as the periarticular fibrosis matures
Method of Securing Suture and Suture Material
suture can be tensioned by:
- hand with a square knot, a sliding (slip) knot, a self-locking knot
- a tensioning device
- suture can be secured by several square knots
nylon leader line
- superior to other types of nylon
- recovers resting tension to a greater degree
- higher failure load and greater stiffness
- elongates less under a given load than nylon fishing line
- biologically inert, low bacterial adherence, and is minimally affected by sterilization
- strength of the line (pound test) is generally chosen to be at least equivalent to the body weight of the patient; however, optimal not been determined.
- estimated load applied to the suture is 120 to 600 N
Mechanical testing of knot type
- metallic crimp: lower elongation, higher load at failure, greater stiffness, and greater initial loop tension compared to square knot
- study: single self-locking knot + double self-locking knot compared with square knot, There was no difference in elongation among the knots, The self-locking knots were stronger and stiffer than the square
loop types
- interlocking loop had the greatest load at yield but also the greatest elongation at yield (which is detrimental to stifle joint stability)
Suture Anchorage Sites
- Ideally, isometric (i.e., the two points would remain equidistant during stifle joint range of motion).
- because of the cam shape of the femoral condyle, and ligamentous and muscular constraints of the stifle, the axis of rotation of the femur relative to the tibia does not remain constant
- complex rolling, sliding, and rotational motion of the femur with respect to the tibia > truly isometric does not exist
strain analysis of femoral and tibial anchorage sites
- traditional fabellotibial suture site [F1] and [T1] = least isometric
- distal pole of the fabella [F2] paired with caudal wall of the extensor groove of the tibia [T3] = the most favorable
- F2 and T3 require a bone tunnel or a bone anchor
- radiographic analysis of the isometry confirms F2 amd T3 sites as being closest
- Anchorage at nonisometric sites shown to result in suture loosening and tightening during stifle ROM in cadaveric study may lead to breakage/elongation (when tight) or instability (when loose)
- variations in individual anatomy likely result in variations in isometric site location
- non truely isometric > quasi-isometric
TightRope + SwiveLock CCL technique, Arthrex
tightrope
- minimally invasive
- uses bone-to-bone anchorage via femoral and tibial tunnels
- flat polyblend suture tape, braided ultra-high-molecular-weight polyethylene polyester (FiberTape)
- secured with suture buttons
- combines quasi-isometric suture anchorage with a high tensile strength suture material with low creep
- STUDY: prospective clinical 6-month outcomes not different to TPLO
- cadaveric STUDY: failure at a significantly greater number of cycles with the TightRope compared to other ex-cap, however: high loads still failed same
Swivelock
- flat polyblend suture tape, braided ultra-high-molecular-weight polyethylene polyester (FiberTape), and a knotless anchor system
- placed at the quasi-isometric points F2-T3
- interference PEEK screw suture anchor eliminate knots and reducing the risk of intra-articular placement of suture material
- elimination of the knot > less creep, which is a slow change in suture length under load
- Retrospective STUDY: major complication rate of 7.3% and good to excellent long-term functional outcomes in all cases
- mechanical STUDY: isolated loops of nylon leader vs polyethylene cord vs tape in bone tunnels or anchor. The anchor– tape, creep was not significantly different than the corresponding isolated prosthetic loops
- used with great success in human joint stabilizing procedures
interference screw: compression fixation device that relies on the screw threads to engage and compress the suture for fixation to bone
extra-cap outcomes
based on clinical examination,
- satisfactory outcomes in 85.7% of 42 dogs
- improvement in 87.5% and normal gait in 60%
- another study 94.1% of dogs were clinically sound at a walk and trot
- retrospective study: clinician assessment + force platform gait analysis, clinicians graded 14 of 18 dogs (77.7%) good - excellent and force platform gait analysis normal in 6 of 7 dogs (85.7%)
force plate
- prospective study: only 40% improved, and 15% returned to normal function
- disparity between clinical exam and kinetic gait analysis highlights the superior accuracy of force platform gait analysis
- rehabilitation group showed significantly higher peak vertical force and vertical impulse 6 months postoperatively compared with no rehab group + not significantly different from that of the normal limb
- benefit of postoperative rehabilitation; massage, walking, and swimming twice daily during weeks 3 to 7 after surgery
TPA
- angle did not appear to have predictive value in terms of outcome in dogs with a TPA 18.5 degrees to 34.9 degrees
Excap vs TPLO in prospective clinical trials
- 80, random, Peak vertical force at a walk and trot was 6% and 11% higher and 93% vs 75% oweer satisfaction
- osteotomy (n = 15) or excap (n = 23) compared to normal control (n = 79) using kinematic gait analysis: TPLO more symmetric limb loading than the lateral fabellotibial stabilization group, TPLO not different from those of the control group by 6 months to 1 year unlike excap group
- authors concluded that dogs achieved normal limb loading faster in TPLO
extra-cap complications
- 17.4% complications (63 of 363)
- 7.2% required 2nd Sx
- higher rate of complications: high body weight and young age of the dog
- intraoperative 0.3%
- Peroneal nerve deficits in 1 dog 0.3%
- surgical site infection 3.9%
- incisional 8.8% (self-trauma, swelling and discharge, and bandage-related)
- implant-related 2.8% (swelling and/or lameness)
- Postliminary meniscal tear rate 15.2%
- 2% required sx
- 0% when meniscal release performed
Fibular Head Transposition
Smith and Torg
- Fibular head is mobilized and advanced cranially
- alters lateral collateral ligament, thereby preventing cranial drawer movement and internal rotation of the tibia
- peroneal nerve should be identified and protected
- small incision is made in the connective tissue between the peroneus longus muscle and the cranial tibial muscle
- Syndesmosis between the fibular head and the tibia is identified
- Two holes are drilled in the tibial crest cranial and distal to the fibular head, and a loop of 18 or 20 gauge stainless steel
- fibular head is advanced cranially with the tibia held in external rotation, and a pin is placed
- wire is looped over the pin in a figure of eight pattern
Outcomes and Complications
- initial report 49 of 71 stifle joints (69%) had excellent function
- retrospective 91.7% to have good or excellent function, and force platform gait analysis normal in 0 of 5 dogs (0%)
- experimental study: ranial drawer motion was not controlled, rotational instability was present, and significant radiographic progression of OA, at 10 months, 50% of dogs had postliminary medial meniscal tears
- significant elongation of the ligament was evident 3 weeks after surgery
- fibular fracture in 10 of 85 dogs (12.5%)
- tearing of the LCL (2.5%)
- postoperative instability (6%)
- seroma formation
Intra-Articular Reconstruction
- long been advocated as a method of ACL repair in humans
- ligament may be reconstructed with other biologic tissues (allograft or xenografts), synthetic materials, or a combination of synthetic and biologic materials (composite grafts)
- Regardless of the tissue > all are avascular at the onset
- incorporation requires revascularization and remodeling that takes ~ 20 weeks to complete
- initial phase of inflammation and graft necrosis, revascularization and cell repopulation, and graft remodeling.
- grafts undergo necrosis, resulting in compromised mechanical properties.
- protect the graft > ligament augmentation device (LAD) placed alongside the graft
- Alternatively, a prosthesis instead, designed to permanently replace the ligament
- interest in scaffolds into the knee (form a neoligament)
- Few data in the clinical realm of veterinary surgery indicate the best material to use > copious experimental studies on animals in human literature
- substitute: mimic not only the native anatomy but also biomechanical properties + must be fixed securely + permit tissue integration (replaces the native CCL)
- Prostheses: permanently replace the native ligament + withstand all of the functional loads + resistant to subsequent wear and failure
different anterior cruciate ligament substitutes
autografts
- bone–patellar tendon–bone,
- hamstring tendon [semitendinosus and gracilis muscles],
- quadriceps femoris muscle tendon,
allografts
- (all of the former)
- Achilles tendon
synthetics
- Dacron,
- silk,
- ligament augmentation devices [LADs]
ACL repair in humans
Review date- Sep 2023
- There is no evidence as yet that reconstruction of the ACL reduces the incidence or progression of degenerative change in the knee, but early stabilization reduces the incidence of subsequent meniscal pathology
- Most surgeons undertake the entire procedure arthroscopically, although
incisions are needed for graft harvest, for femoral tunnel drilling or fixation in some techniques - Allograft: for revisions and primaries in patients greater than 35 years old as they avoid donor site morbidity; however, re-tear rate increases significantly in younger patient
- Synthetic ligaments are not currently recommended for routine primary intra-articular reconstruction.
- Wrapping of graft in Vancomycin soaked swab (5mg/ml), prior to implantation, has been shown to significantly reduce infection rates in ACL reconstruction surgery to approaching 0%
graft types
- Hamstring tendon: slightly higher
re-tear rate when compared with BPTB, main complication being of damage to the infrapatellar branches of the saphenous nerve
- BPTB has a higher rate of pain with suggestion of greater risk of osteoarthritis
- Quadriceps graft: less harvest site morbidity than BPTB with good functional outcome, some studies suggest higher failure rates
ACL graft types
Autograft Versus Allograft
- autograft, there must be low donor site morbidity; PROs: ease of procurement and the absence of immune response
- allograft, there must be low (absent?) potential for disease transmission, PROs: absence of a donor site, quicker surgical time, less postop discomfort (reduce joint stiffness and mm atrophy)
- sterilization and radiation have been shown to negatively impact graft tensile strength
- All tissues used for autograft or allograft have been shown to be stronger than the native
- long-term follow-up has failed to show any statistically significant differences in strength, function, or ligament laxity of allograft compared with autograft reconstructions
- most common indication for use of allografts is revision
Xenografts (bovine)
- use generally has been unsuccessful
- intensity of the inflammatory reaction caused by the immune response
Bone–Patellar Tendon–Bone Versus Hamstring Tendon
BPTB
- 90% to 95% success rate for stability, but 70% success for return of function to preinjury
- advantage = strength of the construct due to the bone-ligament interface.
- By securing (interference screws) the bone ends into bone tunnels rather than soft tissue, immediate stability is obtained
- bone healing occurs rapidly, in approx 6 to 8 weeks > quicker than healing of soft tissue
- higher proportion of patients with anterior knee pain when full function is resumed
Hamstring
- double semitendinosus/gracilis tendon graft, or quad graft
-Fixation within the bone tunnel shortens the graft and with more secure fixation (interference screw), eliminates the previous problem of graft loosening
- slower healing incorporation (soft tissue to bone)
- Long-term results comparable to BPTB
Canine
- patellar ligament and/or fascia lata
- no clinical reports describe the use of a bone-ligament-bone graft in the dog
- proposed as the optimal tissue in the dog > have the greatest strength (comparable to the native cranial cruciate ligament
- experimental tensile testing: maximal load less than one-third of the strength of intact CCL
- may be the attachment/fixation problem of the graft. In the dog, preferred points of graft insertion have not been studied
- historically, femoral tunnel technique has a high failure rate compared with the over-the-top position in dogs
- similar problem for tibial anchorage point > graft left attached to the tibial tuberosity shown to be less variable in centre of rotation studies
- with the over-the-top fixation there is an overall greater length to the graft, where the most proximal attachment is dependent on the soft tissue (fascia) extension proximal to the patella > proposed to be the weak link
- alternative: using the lateral fascia lata, and patellar ligament from the apex of the patella> rerouted under the cranial intermeniscal ligament to the over-the-top position (“under-and-over” technique)
- Based on literature, no consensus regarding the “best” CCL replacement position
Synthetic Grafts
3 types:
permanent replacements (prostheses)
- resume the function of the native ligament without the possibility of ingrowth
- prone to mechanical failure (creep and fatigue) over the long term
- Gore-Tex (polytetrafluoroethylene [PTFE]), and Dacron (polyethylene terephthalate)
- removed from human market due to high failure rates (30-60%) and wear debris (PTFE particles) that caused a synovial reaction
augmentation devices
- protect the biologic graft during early periods when it is the weakest
- may cause stress shielding, resulting in poor graft remodeling/ligamentization
- LARS ligaments (Ligament Advanced Reinforcement System) polyethylene terephthalate, and their structure allows tissue ingrowth in the intra-articular part
scaffolds
- designed to allow/promote tissue ingrowth (porous structure)
- resorbed with time to allow load transfer to new tissue to optimize remodeling process
- bioengineering > the scaffold concept, support cell and tissue ingrowth, leading to production of a neoligament. Progenitor ligament cells are cultured on a matrix scaffold
- scaffold then gradually breaks down > progressive mechanical loading of the structure
- silk fiber matrix
Graft Position/Fixation
- basic principle is to place the device in such a manner as to replicate the attachments of the native ligament
- native ligament is composed of millions of fibers + not attached at a single discrete point but, rather, diffusely over a much wider area
- complex geometry is difficult to replicate
- isometric points such that no change in the length of this structure occurs within the joint throughout the stifle ROM > malposition results in fatigue
- ideal points of femoral and tibial attachment remains to be defined > bone secured with interference screw into tunnels is ‘gold standard’
- In the dog, the preferential position for femoral graft placement remains the over-the-top position
Surgical Technique in the Dog
- A patellar ligament or fascial strip that remains attached to the tibial tuberosity must first be passed intra-articularly and then over the top of the femoral condyle.
- stifle joint extension may impinge upon, and thus compromise, the graft
- with osteoarthritis, the intercondylar notch is narrowed by osteophytes > widen the intercondylar notch (“notchplasty”)
- vertical incision is made in the tendon of origin of the gastrocnemius muscle proximal to the lateral fabella
- ascial graft, it first can be passed under the cranial intermeniscal ligament (“under-and-over” technique)
- pretension the graft to eliminate any laxity, joint in extension (assess for draw)
- secure the graft proximally is to tie the suture around a screw placed within the distolateral femoral diaphysis
- graft length is recommended to be approximately 1.5 times the patella-tibial tuberosity distance
- patellar ligament graft can be harvested (autograft or allograft) with a segment of bone
- tibial attachment > approximating the craniomedial band attachment may be the preferred position, bone tunnel through to tibial crest
- the suture is secured to the femur with a screw and washer and then tensioned appropriately and secured in the tibial bone tunnel with an interference screw
- soft-padded bandage or cast for 2 weeks or up to 4 weeks
graft complications
- approximately 90% good to excellent results
- Intraoperative complications revolve primarily around procurement of the autograft
- Errors, or difficulty in obtaining the appropriate wedge of the patella > predispose to OA
- Fracture of the patella
- insufficient size of the patellar wedge > eary graft failure (weakness at the patellar ligament/bone interface)
- inadequate width of fascia lata
- inAdequate stability/anchorage of the graft
- persistence of some degree of craniocaudal joint laxity
- graft lengthening during the remodeling process > often, this is the result of soft tissue-to-bone fixation methods
- movement of the graft in line with the bone tunnel “bungee effect”
graft outcomes in dogs
- It has been suggested that the ultimate joint stability that resulted in these cases was due to periarticular fibrosis rather than to the presence of the intra-articular graft.
- severe laxity develop are probably caused by loss of integrity of the intra-articular graft
- STUDY: extra-cap vs TPLO vs intra-articular patellar ligament graft, the patellar ligament graft was inferior as determined by force plate analysis
loss of confidence in this technique has more to do with the lack of postoperative compliance in our patients compared with a carefully controlled postoperative rehabilitation regimen in human
Cranial Tibial Closing Wedge Osteotomy
Slocum and Devine
- leveling the tibial plateau angle by removing a cranially based wedge of bone from the proximal tibia
- biomechanical rationale is similar to TPLO > magnitude of thrust during weight bearing in CCL–deficient stifle joint is dependent on slope of the tibial plateau.
- reducing TPA, CCWO mitigates the cranially directed femorotibial shear force
- results from static limb models do not account for all muscular forces > Additional in vivo kinematic studies are necessary to validate this technique
- difficulty associated with attaining the target tibial plateau angle may be attributed to variability in size and position of the ostectomy and tibial long axis shift
- A retrospective analysis: more proximal osteotomy and aligned cranial cortices were more likely to have a postoperative tibial plateau angle near 6 degrees.
- Apelt et al: cadaveric study validated wedge corresponding to TPA +5 or +7.5 degrees, at the distal extent of the tibial crest result in a stable stifle joint and achieved a postoperative TPA of approximately 6 degrees (caution, as cranial cortices were not aligned in study)
- individual assessment > target tibial plateau angle of 4 to 6 degrees
- large wedge can shorten the tibia and alter the femoropatellar joint, lowering the patella relative to the femur and leading to hyperextension of the stifle joint
- Kinematic gait analysis shown an increase in extension during the swing phase of the stifle and tarsocrural joints > significance of these gait alterations is unknown
- steep tibial plateau angles (i.e deformities) would assume a more anatomically correct alignment after cranial tibial closing wedge osteotomy
Techniques for CCWO osteotomy position (4)
- Slocum 1984 – initial osteotomy perpendicular to long axis of the tibia
- Oxley 2013 – isosceles triangle
- Frederick 2017 – perpendicular osteotomy and cranial juxtaarticular wedge for eTPA (technique described by Wallace 2011)
- Christ 2018 – proximal osteotomy parallel to TPA, distal osteotomy created to make prox osteotomy equal to width of tibia
Moreira 2024 review
– assessed effect of different techniques for CCWO on TPA and tibial morphology
- TLA shift and tibial shortening varied with CCWO technique
- Frederick 2017 → highest TLA shift
- Oxley 2013 → highest tibial shortening and wedge base size
- Slocum 1984 – required the most craniocaudal translation to align cranial cortex
- generated calculations for wedge angle for each technique that accurately predicted post- TPA 4-6°
consequences of large CCWO (6)
alternatives? (2)
large wedge can:
- shorten the tibia
- alter the femoropatellar joint
- lower the patella relative to the femur
- lead to hyperextension of the stifle
- periarticular soft tissue may not have enough compliance to accommodate such a significant change
- tilts the distal portion of the tibial shaft in relation to the proximal portion > result in cranial tibial long axis shift
alternative:
- smaller wedge + extracapsular stabilization
- combination of TPLO + CCWO
outcomes of CCWO
Pro’s
- not requiring specialized equipment as for radial osteotomy
- address tibial angular deformity without loss of bone apposition
- distal displacement of the patellar ligament attachment > used to treat patella alta
- performed in dogs with open tibial growth plates
CONS
- variability in postop TPA,
- patella baja,
- limb shortening
- craniocaudal angulation of the tibia.
-17 dogs, Slocum and Devine: return to function and clinical union by 6 weeks, 9 dogs at 12 months subjectively normal. The dogs also underwent muscle advancement (confounding assessment)
- retrospective 91 dogs, 86% good to excellent according to owner and physical exam
- small-breed dogs with proximal tibial deformities: good to excellent
- TPLO vs CCWO: similar outcomes, not return back to pre-injury in either group, complications CCWO more likely to require revision.
complications of CCWO
- second-surgery rate for CCWO was 11.9% -nearly twice TPLO (4.5%) + 9 catastrophic tibial fractures
- no difference in major complication rates or reoperation rates: (TPLO 7.2% and 6.1%, CCWO 9.5% and 5.4%)
- failure of fixation
- nonunion
CCWO surgery
- standard joint exploration and meniscal evaluation via arthroscopy or arthrotomy
- medial approach to the proximal tibia
- +/- TPLO jig
- osteotomy should be as proximal as possible
- caudolateral muscle envelope is elevated and protected to reduce bleeding
- proximal osteotomy is initially performed using an oscillating saw through the medial, caudal, and cranial cortices
- distal osteotomy is marked using a wedge template
- A trigonometric method can be used
- ensure that the osteotomy lines (from medial to lateral) are parallel to the transverse plane of the joint and coplanar to each other, unless a biplanar wedge is being performed to correct an angular deformity.
- Reduction of the cranial tibial closing wedge osteotomy is accomplished by applying a compressive force to the ostectomy gap
- Precise correction of the tibial plateau angle will be accomplished only with precise apposition of the ostectomy site
Reported accuracy of cranial closing wedge ostectomy variants for management of canine cranial cruciate ligament insufficiency: A systematic review and meta-analysis
May 2023The Veterinary Journal TPLO
Concerns have been raised about the predictability of achieving appropriate tibial plateau angles (TPA), the occurrence of axis shift and tibial length reduction following cranial closing wedge ostectomy (CCWO). The primary objective of this review was to quantify typical errors in achieving target TPA with CCWO, with secondary objectives of assessing axis shift and length reduction. Retrospective or prospective studies of CCWO. Extracted data from 11 included studies were tabulated and underwent meta-analysis using R. Mean errors in TPA after CCWO ranged from -0.6° to 2.9°, indicating the possibility of both under- and over-correction depending on the selected technique. Errors were relatively consistent for technique subgroups. Mean axis shifts ranged from 3.4° to 5.2°, and length reduction ranged from 0.4% to 3.2% of initial length, based on 6/11 and 3/11 studies, respectively. Data had high heterogeneity, many studies had small populations, and reporting standards were inconsistent. Concerns about the predictability of postoperative TPA may be overstated. With the limited data available, limb shortening does not appear to be a clinically important consideration. Axis shift will occur to varying degrees and must be considered during CCWO planning, as it influences the postoperative TPA. Careful choice of CCWO technique may allow clinicians to reliably achieve predictable TPA values.
TPLO
Warzee study
- intended to neutralize cranial tibial thrust.
- procedure has proved to be very effective at neutralizing cranial tibial subluxation in the cranial cruciate–deficient stifle joint
- procedure does not prevent internal tibial rotation or hyperextension
- TPLO does not create normal kinematics of the stifle joint (no surgery to date does)
To ensure accurate outcome:
- basic concepts of osteotomy, including meticulous preoperative planning, accurate execution of the procedure, robust fixation, and early return to function
Warzee study suggests that, during stance phase, tibial plateau leveling transforms cranial tibial thrust into caudal tibial thrust, thereby stabilizing the stifle in the cranio-caudal plane via the constraint of the CaCL. The increase in CaCL stress, which results from tibial plateau rotation, could predispose the CaCL to fatigue failure and therefore would caution against tibial plateau over-rotation
TPLO and Caudal cruciate
- cadaver models (warzee 2001): tibial plateau segment rotation resulting in TPA ~ 6.5 degrees neutralizes cranial tibial subluxation
- leveling to less induces caudal tibial subluxation and increases strain on the caudal cruciate ligament
- caudal cruciate ligament: undergo degeneration in dogs with experimentally induced CCLR; thus, excessive rotation may result in further degenerated caudal cruciate ligament
what change in femoral contact area following TPLO?
Analysis of contact mechanics of the stifle joint revealed that the femoral contact area on the tibial plateau at the stance phase is located more caudal than normal following tibial plateau leveling osteotomy
TPLO Preoperative Planning
mediolateral rad (sagittal plane)
- measure the tibial plateau angle,
- determine saw blade size,
- identify osteotomy location,
- quantify the magnitude TP rotation,
- confirm rotation is within safe, acceptable limits
- stifle and tarsocrural joints are flexed to a 90-degree angle
- ideal rad: femoral condyles and tibial condyles are perfectly superimposed
- centering the radiographic beam on the stifle joint minimizes radiographic projection artifact (measured tibial plateau angle closer to the anatomically measured)
- - cranial and caudal extents of the medial tibial condyle determines the tibial plateau axis (prox. orientation line)
- intercondylar tubercles of the tibia and the center of rotation of the talus determines the tibial long axis (mechanical axis)
caudocranial rad (frontal plane)
- screen for the presence of angular or rotational deformities
- identify the location of the fibular head with respect to the joint surface
- Quantification of tibial alignment in the frontal plane is facilitated by using the proximal and distal tibial joint orientation lines
- The mechanical axis of the tibia: midpoint between the intercondylar tubercles of the tibia to the center of the distal intermediate ridge of the tibia. The mechanical medial proximal tibial angle (mMPTA) and the mechanical medial distal tibial angle (mMDTA) can be measured
tibial plateau angle
- measured at the intersection of the tibial plateau axis and the tibial long axis lines with reference to a line perpendicular to the tibial long axis
- tibial plateau axis perpendicular to the tibial long axis would be assigned a tibial plateau angle of zero
- magnitude of rotation of the tibial plateau determined from chart designed to achieve a 5-degree postop
- plateau segment provides buttress support for the tibial tuberosity > it can be safely rotated to a point that is even with the patellar ligament attachment on the tibial tuberosity (consdier CCWO + TPLO if lower)
what are the mechnical medial angles of prox and distal tibia?
- mMPTA = 93.30 ± 1.78 degrees
- mMDTA = 95.99 ± 2.70 degrees
How to determine if tibial torision present?
- historically: medial edge of the calcaneus should bisect the distal intermediate ridge of the tibia in tru straight CC rad > method has been shown to be susceptible to radiographic positioning artifact
- Clinical examination is useful
- computed tomographic ideal method for accurate quantification of tibial torsion
measuring TPA
average TPA in most dogs is 23° to 29°
- Intraobserver variability of ±3.4 degrees
- interobserver variability of ±4.8 degrees of tibial plateau angle
- significant difference between inexperienced and experienced observers was noted
- degenerative changes on the caudal aspect of the tibial plateau were found to obscure the identification of the caudal aspect of the articular surface of the medial tibial condyle
Tibial Plateau Leveling Osteotomy Position
- centered position
- ideal position would allow accurate leveling with no further anatomic alterations
- radial osteotomy > the center dictates the center of rotation of the tibial plateau segment
- five positions with respect to the proximal tibial long axis point (the point dividing the intercondylar tubercles) can be considered, namely cranial, caudal, proximal, distal, and centered
- structures of the tibial plateau segment follow an arc determined by the distance from the center of osteotomy to the structure itself, termed the distance of eccentricity (Kowaleski)
- tibial plateau and the proximal tibial long axis points are all contained within the proximal segment, so they move in unison
- unless the osteotomy is centered on the proximal tibial long axis point, this point will change in position after rotation of the tibial plateau segment, causing a shift of the tibial long axis (mathematically most accurate)
- tibial axis shift affects the achieved postoperative TPA
- rotation should occur around the intersection of the tibial plateau and the tibial long axis = approximates the anatomic tibial plateau.
- result in slight translation of the intercondylar tubercles > BUT the plateau will be accurately leveled = the goal
biomechanical study evaluating the effect of osteotomy position
- centered osteotomy position more effective than the distal in neutralizing cranial tibial thrust because of the more accurate tibial plateau leveling that is achieved
Kowaleski 2005
– distal centering of the TPLO
→ craniodistal translation of tibial plateau
→ higher post-leveling TPA and inadequate neutralisation of cranial tibial thrust
Kowaleski 2004
– centering of osteotomy away from a point dividing the intercondylar tubercles
→ movement of tubercles, tibial long-axis shift and deviation from planned TPA
osteotomy position must be altered when:
because of variations in individual anatomy
- narrow proximal tibia > osteotomy is moved caudally
- low vs high patella insertion
- excessive tibial plateau slope or proximal tibial growth deformity
- presence of a bone tunnel from a previous surgery (lateral fabellotibial suture)
- medium-breed dogs with small tibial size but large body weight
TPLO Angular and Torsional Corrections
- magnitude of deformity in the frontal plane determined by using CORA (Dismukes et al)
- computed tomographic determination of tibial torsion is recommended
- Modest corrections in the frontal plane (varus and valgus) can be accomplished by sliding the distal jig arm > Sliding the jig arm medial (away from the tibia) will correct varus and sliding the jig arm lateral (toward the tibia) will correct valgus.
- these corrections occur at the expense of apposition of the tibial osteotomy (radial opening wedge osteotomy)
- increases stress on the fixation; thus, maintenance of bone contact on the opposite cortex and robust plate fixation
Thickening of the patellar ligament
Kerf = width of material removed by the cutting/sawing process
- common following TPLO and may cause lameness in the first few months
- STUDY: 13 of 31 stifles at 1 month postoperatively, in 9 of 18 stifles at 2 months postoperatively, lower postoperative TPA (<6 degrees) and greater body weight were associated with a higher risk
- speculate that increased stress on the patellar ligament following TPLO may play a role
- kerf size and position of the osteotomy shown to affect the distance from the patellar ligament attachment on tuberosity to the intercondylar tubercles of the tibia following rotation.
- distance represents the lever arm from which the quadriceps mechanism gains mechanical advantage in extending the stifle joint. As this distance is reduced, the force on the patellar ligament during weight bearing may be increased, resulting in patellar ligament strain
- A shorter lever arm requires more force to move an object the same distance
- Histologic analysis: collagen fiber disorganization, neovascularization with lack of inflammation = supporting a biomechanical basis
- Other potential causes include trauma during sx
- radiographic grading: grade 0—mild, normal up to double preoperative thickness; grade 1—moderate, 6 to 11 mm in thickness; and grade 2—severe, ≥12 mm
- demitis = grade 2 thickening, lameness attributable to the patellar, pain on palpation of the patellar ligament, and soft tissue swelling.
Risk factors
- cranially positioned osteotomy
- partially intact cranial cruciate ligament
- postoperative tibial tuberosity fracture
Tibial Plateau Leveling Osteotomy/Cranial Closing Wedge Ostectomy
Y = X tan(Θ) for CCWO
- excessive (steep) TPA (angle >34 degrees with 24 mm saw radius or when rotation past the insertion of the patellar ligament
- combined with a medial or lateral closing wedge osteotomy to address varus or valgus and/or torsion
- TPLO planned first > amount of safe rotation is determined by measuring the distance along the osteotomy that the plateau can be rotated once segment is even with the patellar ligament attachment
- CCWO is planned to correct the remaining tibial plateau angle
- CCWO positioned such that the apex is placed at the caudal cortical margin of the tibial plateau leveling osteotomy
- TPLO cut, segment is rotated and secured with two Kirschner wires, the CCWO is completed, and the ostectomized segment is removed. The tibial segments are reduced and secured with a pin distal to proximal traversing all three bone segments, to provide temporary stabilization until the tension band wires and plate(s) are applied
- varus or valgus with eTPA> CCWO can be performed as a biplanar wedge, rather than as coplanar
- alternative is to insert two jig pins parallel to the proximal and distal tibial articular surface, and cut parallel
- cases with patella alta, the closing wedge can be used to position the patella more distally (TPLO rotation can be adjusted to compensate)
Tibial Plateau Leveling Osteotomy/Cranial Closing Wedge Ostectomy surgery
- modified by Talaat and others to utilize linear osteotomies for CCWO (rather than second radial as per slocum)
- TPLO osteotomy is made partially > proximal CCWO is scored on the medial cortex so that it intersects the radial osteotomy
- CCWO created using sterile angle template, a sterile goniometer, or a simple geometric method
- TPLO completed ad stabilised with 2x kwires
- CCWO performed, wedge reduced and cranial cortices aigned and compressed with a wire is placed from craniodistal to caudoproximal
- tension band placed, then TPLO plate
- wedge can be morselized and placed as autogenous corticocancellous bone graft > cranial closing tibial wedge ostectomy site heals most slowly
- lateral translation of the tibial tuberosity segment can be accomplished before the fixation is applied i.e. for medial patellar luxation
- fixation of the cranial tibial tuberosity segment must be rigid because the distractive force of the quadriceps mechanism is considerable: wires should be of a suitably large gauge [2.4 mm] Steinmann pins and 18 gauge or 16 gauge orthopedic wire in most patients
- Double plate fixation is recommended if tibial size is sufficient to place a second bone plate; in patients weighing 30 to 40 kg
TPLO and MPL
1.TPLO + TTT + trochleoplasty
- TPLO performed first
- TTT cut started same level as the insertion point of the patellar ligament onto the tibial tuberosity
- ensure that the tibial tuberosity segment is of sufficient size and shape to
mitigate the possibility of a fracture and
allow for application of adequate fixation
- fulcrum effect that is created when a TPLO is combined with a TTT
- Birks and colleagues found that load to failure for a TTT was higher than with a TPLO and TTT.
Redolfi 2024: retrospec, 24 stifles, grade III or IV MPL, low mj complication rate (18%): surgical site infection (n = 3) and recurrent grade II MPL (n = 1), long term >1yr 21/22 clinically sound and 23/24 stifles complete resolution of MPL. TT cut is differnt location to leonard
Leonard 2016: Patellar re-luxation did not occur in any of the 13 stifles available for in-hospital follow-up, short follow up, patella lig thivken 7/13
2.Modified tibial plateau levelling + trochleoplasty
- tibia laterally translated by 3 to 6 mm and was externally and abaxially rotated
- plate contour: proximal portion forming approximately a 30° angle and medially
twisted
- six grade 2 and seven grade 3 MPL
Langenbach 2010: 12 dogs, two cases, one due to failure of fixation and another due to screw breakage, No patella luxated
alternatives
- TTA- TTT (recession sulcoplasty may affect PTA)
- TTO with TTT
- TTT with extra-cap
- CBLO with TTT (cadeaver study, maintains a buttress effect of the tibial crest against the tibial plateau, load to failure same TTT vs CBLO-TTT)
Newman 2014 – TTTA more effective at lateralization of TT vs pin and tension band wire
- no significant difference in peak load and energy to failure or stiffness
Hackett 2021 – mini-TTTA vs ECS+TTT
- no significant difference in clinical outcome at 8w
- mini-TTTA → 1/27 reluxation, ECS+TTT → 5/26 major complication (failure/explant)
Technique and Outcome of a Modified Tibial Plateau Levelling Osteotomy for Treatment of Concurrent Medial Patellar Luxation and Cranial Cruciate Ligament Rupture in 76 Stifles
Kathryn Flesher
- restrospective, <15kg using fixin plate
- complications: overall 18.4%, reluxation 6.6% vs 8.8% non-translation group
- decreased bone apposition at osetotomy sire: The mean healing time of 73 days observed in the treatment
group was similar to the healing time observed in our control - a modified TPLO with no difference in complication
rates when compared with traditional surgical techniques.
Application of this TPLO technique results in a small shift in
the mechanical axis of the tibia - no compression achieved bewteen fragments
- gap between plate and bone??
TPLO vs TTA
primary stabilizer of the joint becomes the CaCL after TPLO or TTA
personal surgical preference is a major factor in case selection
1. late meniscal tears: TTA up to 21% in older report
2. proposed increased stress (TPLO) versus decreased stress (TTA) on the patellar tendon > Theoretically, diminished force can protect the articular cartilage of both the patella and the femur from subsequent damage
3. Femorotibial contact pressure and location: TTA appears to restore the normal femorotibial contact and pressure
distributions, whereas TPLO results in a decrease (12%) of contact area and caudal positioning of peak pressure distribution
4. The tibial plateau remains unaltered with TTA, whereas with TPLO, the tibial plateau is effectively placing the joint in 15–20 degree of increased flexion
5. tibiofemoral shear force is dependent upon PTA > altering the direction patellar tendon force obtains dynamic joint stability. either parallel to the patellar tendon (TTA) or to the functional axis of the tibia (TPLO), the difference could account for as much as 10–15 difference in endpoint after surgery > appear that the TPLO overcorrects for the cross-over point compared with TTA
6. TTA correcting the tibiofemoral shear force closer to neutral at full extension during weight bearing, thus there may be less stress placed on the CaCL.
reoperation 5-9% TTA 11% TPLO
Pivot shift
- sudden internal rotation of the tibia with lateralization of the hock, and a sudden lateral change in direction of the stifle joint during weight bearing
- reason for its occurrence is also unknown, but is thought to be a result of insufficient correction of tibial torsion or angular deformity
- 3.1% pivot shift after TPLO
- medial meniscectomy → risk factor for pivot shift
Dx
- tibial pivot compression test (lampart 2023)
- External rotation and valgus stress are applied.
TTA surgical planning
- mediolateral radiographic projection is centered on the joint close to full extension (approximately 135 degrees)
- recommended that the patellar tendon angle should be determined by using the common tangent between the tibial and femoral surfaces at their contact point
- Less variation has been reported using the contact point compared with PTA
- contact point is determined by drawing circles of the femoral condyles and the tibial plateau; this line measure the amount of advancement required to achieve a 90-degree angle with the patellar ligament
- Errors will occur because of anatomic variability (tibial drawer or stifle joint extension angle), patellar ligament insertion point (high vs. low), variation between measurement methods
Surgical Technique (Tibial Tuberosity Advancement: Cage and Plate
- aponeurosis incision is made a few millimeters caudal and parallel to the tibial crest + periosteum of the tibial crest is reflected cranially
- eight-hole drill guide (Kyon) is positioned parrallel to crest, first hole aligned at patellar ligament attachment and predrilled
- cranial tibial margin should intersect approximately at the level of the screw hole in this distal portion of the plate (after advancement plate holes will be central tibia)
- osteotomy, from a point immediately cranial to the medial meniscus (and cranial to the tendon of origin of the long digital extensor muscle)
- partial osteotomy performed first
- advancement plate (Kyon) is contoured
- A fork designed to fit within the tension-band plate is secured into the tibial crest by impaction
- crest with attached plate is moved cranially by using a spacer attached to a T-handle that corresponds to the selected cage width
- “ears” of the cage (screw holes) are contoured: an upward bend caudally, and a downward bend cranially.
- cage placed approximately 2 to 3 mm from the proximal tibial bone margin
- entire tibial crest is allowed to shift a few millimeters proximally to ensure that the patella position remains unaltered (arc of rotation remains centered at the patella)
- bone graft ?? auto or allograft
- apposition of the aponeurosis of the medial thigh muscles to the periosteum of the tibial crest to cover the implants
- rads and bandage post-op
Surgical Technique (Tibial Tuberosity Advancement: Cage Only)
- eliminated the plate, instead relying only on the cage to provide the advancement and stability.
Modified techniques:
- Modified Maquet Procedure
- TTA Rapid
- TTA-2
- forkless TTA (Matchwick 2021)
- biomaterial wedge for MMP (terreros 2021)
Distal (Low) Versus Proximal (High) Patellar Ligament Insertion Point
proximal patellar ligament attachment
- larger tibial tuberosity/crest
- larger plate can be applied to the tibial crest.
- The cage is buttressed with adequate bone> theoretically will disperse all the forces applied to the tibial crest.
distal patellar ligament attachment
- smaller tibial tuberosity/crest,
- smaller plate is applied to the tibial crest.
- cage located proximal to the most proximal position of the plate, and little bone is present for support.
- risk of fracture may be greater as the result of lesser buttress support
Patellar Luxation and TTA
- tibial tuberosity advancement can be performed simultaneously
- plate is slightly overbent to conform
- the cranial cage ear may be elevated off of the bone [tuberosity] by placing one or two small metal washers under this ear
- No additional fixation is usually required (pins and 8 wire )
Triple Tibial Osteotomy
- similar to TTA = reduce the patellar tendon angle to 90 degrees at weight-bearing angle
- Three cuts in the proximal tibia create a partial wedge ostectomy caudal to a partial tibial crest osteotomy
- The tibial plateau is made perpendicular to the patellar ligament by rotating the proximal tibial fragment to close the wedge ostectomy and simultaneously advancing the tibial tuberosity.
- biomechanical investigations evaluating the effectiveness of TTO in neutralizing the cranial tibial thrust force are limited (only one Jensen 2020)
TTO surgery
The wedge angle (WA) can be calculated according to Renwick et al (modification of Bruce et al)
WA = 0.6 X CA + 7.3
CA is the angle of correction of the patellar tendon angle needed to achieve 90 degrees.
- If TPA - WA is less than 0 degrees, instead WA calculated as TPA – 5 degrees
- if preop patellar tendon angle close to 90 degrees, instead WA calculated as TPA – 12 degrees
- transverse 2.0 mm hole is drilled caudal to the cranial cortex at a distance equal to the length of the patellar ligament distal to the patellar ligament attachment
- crest osteotomy performed > wedge of precalculated size is marked at midpoint
- The apex of this wedge is a predrilled 2 mm hole cranial to the caudal cortex
- wedge closed and stabilsied with plate
- if crest fractures at distal attachment > pin and tension band is applied
- Cancellous bone graft
CBLO
- CORA-based leveling osteotomy: correction of anatomic axis CORA (procurvatum of tibia)
- The normal canine tibia has a proximal curvature (procurvatum)and therefore, has a CORA.
- proximal anatomic longitudinal axis is not aligned with the distal anatomic longitudinal axis. When the proximal and distal anatomic lines are drawn, the intersection of the anatomic proximal and distal axis lines defines the position of the CORA
- CORA angle = angle of correction to achieve desired TPA
→ post-operative TPA 9-12° - post-TPA 9-12° to maintain compliance of cranial soft tissues
→ potentially reduce cartilage wear and joint degeneration - neutralization of the quadriceps disruptive moment was achieved with a screw
- moves the tibial crest cranially
TPLO suggested to have significant joint mechanical alteration which may be contributory to articular cartilage lesions.
- abnormal joint mechanics because osteotomy is not based on the mechanical or anatomic CORA.
- Axis of Correction (ACA) is not aligned with the CORA resulting in mal-alignment and secondary translation.
- result is caudal displacement of the weight bearing axis and a focal increase in joint force. (TPLO creates a caudal thrust)
- Hulse et al: CBLO proposes to maintain normal stress distribution and kinematics of stifle and achiev 90 degress PTA
- also eliminate cuadal thrust and therefore cranial cartilage lesions
- the PTA curve following CBLO is consistent with placement of the joint into relative flexion by rotation of the proximal metaphysis during surgery.
TPA measurement methods
ther TPA measurement methods focusing on tibial plateau slope determination usingdifferent types of proximal tibial axes have also been described in the literature [12-14]. However, regardless of the method used, radiographic evaluation of TPA is stillvery subjective [9]. It was confirmed that TPA measurements can be misinterpreted incases of poor limb positioning when the x-ray beam is not centered on the stifle jointduring radiographic imaging [15]. Also, severe osteophyte formations around tibialcondyles can hinder the identi fication of the cranial and caudal margins of the tibialplateau [10].
CaCLR diagnosis
- vary in severity from mild weight-bearing lameness to non–weight-bearing
- differentiation of caudal drawer motion from cranial drawer motion is difficult > 7 of 14 dogs were misdiagnosed as having a cranial cruciate
- Rupture of the caudal cruciate ligament results in caudal subluxation and reduced prominence of the tibial tuberosity (tibial sag)
- distinguishing cranial from caudal drawer > in CaCL, the thumb placed behind the fibular head travels from caudal to the thumb behind the fabella to a position approximately even with it.
- draw > abrupt stop as CrCL becomes taut = sharp and distinct endpoint. CrCLR is less distinct.
- Radiographs: fractures, avulsion fragments, and OA
Avulsion Fracture
- Avulsion of the femoral attachment appears to be more common
- fixation with bone screw or a wire suture formed from a loop of cerclage wire placed through bone tunnels or divergent Kirschner wires
midsubstance tear CaCLR
- remnants of the caudal cruciate ligament are debrided, and the joint is explore
medial side
- caudomedial joint capsule can be imbricated with mattress 3/0–0 sutures
- large 0–4 braided polyester, or nylon leader line suture can be placed from just distal to the apex of the patella to a drill hole in the caudomedial tibia
lateral side
- large suture from the proximolateral edge of the patellar ligament just distal to the apex of the patella to a drill hole in the fibular head
- caudolateral joint capsule can be imbricated with mattress sutures
desmodesis of the medial collateral ligament or tenodesis of the long digital extensor tendon or popliteal tendon can be employed
- Exercise restriction is recommended for 6 weeks
- outcomes following extracapsular stabilization of avulsion fragments are very good, despite the stability achieved
The significance of the meniscal flounce sign in canine
stifle arthroscopy
Landon R. Katz 2022
Prospective cohort study, 130 stifles
A total of 41 stifles (31.5%) had a negative meniscal
flounce. Of these stifles, 38 had a meniscal tear
sensitivity, specificity, positive
and negative predictive values, and diagnostic accuracy of the meniscal
flounce sign for indicating an intact or torn meniscus were 96.6%, 90.5%,
95.5%, 92.7%, and 94.6%, respectively.
The absence of the sign strongly indicates the presence of meniscal pathology.
The meniscal flounce, a fold in the free, unanchored inner edge of the medial meniscus, is a common arthroscopic finding in dogs
In people, the absence of a meniscal flounce is a strong predictor of the presence of a medial meniscal tear
Compression through Fragment Rotation during Tibia
Plateau Levelling Osteotomy: An Angiographic
Three-Dimensional Reconstruction
Lena-Charlott Cieciora 2022
12 pelvic limbs from six large-breed canine cadavers before and after TPLO
In all adequately rotated
fragments, the mean caliber of the artery on the level of the osteotomy was 1.57mm2 (0.89–2.93mm2) after TPLO. This represented a significant decrease of approximately
81%.
Sufficient fragment rotation leads to compression of the cranial tibial
artery. Intraoperative hemorrhage can be caused by laceration of themain cranial tibial artery or by multiple small branches reaching craniolaterally
- study to show what happens if pack that area?
If the blood circulation is impacted,
postoperative complications such as tissue swelling, edema,
seroma, and other healing disorders must be taken in
consideration, including infection??
Matres-Lorenzo L, McAlinden A, Bernardé A, Bernard F. Control of
hemorrhage through the osteotomy gap during tibial plateau
leveling osteotomy: 9 cases. Vet Surg 2018;47(01):60–65
A Gelpi retractor was introduced tangentially and
approximately at middistance of the osteotomy line between
the tibial fragments
temporary digital pressure was applied
on the medial aspect of the thigh at the distal third to fourth
of the femur. This maneuver compressed the distal femoral
artery
2 suction tips were used
Moles and Glyde9 have described a surgical approach in
cadavers to allow temporary occlusion of the popliteal artery
proximal to the stifle joint to decrease blood loss and
improve visualization while the surgeon attempts to control
hemorrhage. This technique requires exposure of the cranial
tibial artery just proximal to the medial femoral condyle in
the popliteal fossa by separating several muscles
Center of rotation of angulation-based leveling osteotomy
for stifle stabilization in skeletally immature dogs
Peycke 2022
short-term outcomes, Retrospective case series.
Animals: Fifteen skeletally immature dogs (16 stifles).
(TPA) was 26 preoperatively, 9 postoperatively,
and 9 at final recheck. One dog developed 10 recurvatum of the proximal
tibia secondary to inadvertent over rotation of the tibial plateau (TPA 3 )
Two dogs developed
a valgus deformity secondary to a plate screw engaging the distolateral
aspect of the proximal tibial physis.
CBLO osteotomy is positioned distal to the proximal tibial physis thereby allowing the use of this
technique in dogs with active growth potential
4 avulsions, no meniscal tears
Of 16 stifles, 8 stifles had additional
stabilization with a countersink compression screw
(CCS),5 5 stifles had additional stabilization with
2 0.062 K-wires, and 3 stifles received a single plate
alone
apophyisis remained open with k-wires bt not CCS
Conclusion: The risk of patella fractures increased as TPAs after TPLOs
decreased.
Clinical Significance: Care should be taken to avoid excessive rotation during TPLO to decrease the likelihood of postoperative patellar fractures.
Most dogs in our
fracture group presented with lameness, but others were
identified incidentally on routine follow-up radiographs.
Kanno et al. showed that shortening of the patellar
ligament moment arm (PLMA) with TPLO, as occurs
when the intercondylar eminence is shifted cranially,
increases the tensile force of the quadriceps
studies
demonstrate disruptions to normal patellar kinematics
and forces following TPLO which could additionally
increase stress on the patellar ligament
Use of a Modified Tibial Plateau Levelling Osteotomy
with Double Cut and Medial Crescentic ClosingWedge
Osteotomy to Treat Dogs with Cranial Cruciate
Ligament Rupture and Tibial Valgus Deformity
Luca Vezzoni 2020
cases series. Fifty-two surgical procedures performed in 45 dogs
Intraoperative complications occurred in two stifles. No postoperative complications were recorded
and all osteotomies healed uneventfully.
A limitation of the study was that the mMPTA was
measured using the conventional method described by Dismukes
and colleagues because it was the only one validated
at the time of our first cases.16 The tangential method
described by other authors has been shown to be more
accurate.
( This was accomplished by
raising the distal aspect of the tibia until the angle between the
radiographic table and the mechanical axis of the tibia was
equal to the measured TPA)
it has been shown that experimentally
induced valgus deformity of the proximal tibia in
Beagles leads to the development of osteoarthritis
Fibular osteotomy to facilitate proximal tibial rotation during
tibial plateau leveling osteotomy
Joshua S. Zuckerman
Study design: Retrospective case-control study.
Animals: Dogs undergoing TPLO-FO (n = 23) and dogs undergoing routine
TPLO (n = 49).
Proximal tibiofibular synostosis and a relatively wide fibula restricted
tibial plateau rotation. In these dogs, concurrent fibular osteotomy allowed adequate
rotation. Adjunct plate fixation limited loss of rotation after TPLO-FO.
synostosis was identified
as a radiographic ossification bridging the proximal tibiofibular
joint
Because the tibiofibular articulation is relatively
close to the ideal center of rotation, deviation of the osteotomy
in a craniocaudal or proximodistal direction will result
in a shift of this articulation away from the center of rotation,
thus increasing the moment of inertia and requiring a greater
force to achieve the planned rotation
complications: mild lateral collapse of the osteotomy site resulting in a proximal tibial valgus deformity + transient peroneal neurapraxia
The fibula did not heal completely in any of the dogs
reported here; rather, poor or undetectable healing was diagnosed
in 45% of cases.
Discrepancy between true distance of tibial tuberosity
advancement and cage size: An ex vivo study
Dong-Woo Jin
the tTTA was less than the corresponding
cage sizes by at least 1.5 mm in all but the 6-mm cage. The
6-mm cage resulted in a median tTTA of 4.3 mm, but it was
not significantly different from 4.5 mm. The underadvancement
measured in this study was greater in magnitude compared
with previous studies
Selection of a larger cage size during the TTA may be
advantageous to compensate for underadvancement and to minimize the risk of
residual cranial tibial translation.
Effect of the Centre of Rotation in Tibial Plateau
Levelling Osteotomy on Quadriceps Tensile
Force: An Ex Vivo Study in Canine Cadavers
Nobuo Kanno 2019
The tensile force of the quadriceps muscles changed in accordance
with the centre of the osteotomy in TPLO. The distally centred group had increased tensile force,
which may cause patellar ligament thickening after TPLO. Setting the postoperative
TPA at 6° may cause excessive rotation in patients with a normal tensile force of the stifle flexor muscles.
The patellar ligament moment arm (PLMA) is associated with
stifle biomechanics, and is defined as the perpendicular distance
between the patellar ligament force and the centre of the
tibiofemoral contact.1 Geometrically, the moment arm is the
perpendicular distance from the line of force to the motion
axis. A longer moment arm requires less force to move an
object (the tibial tuberosity) compared with a short moment
change in the PLMA is minimized and the cranial tibial displacement
after TPLO is reduced by setting the osteotomy centre on the
intercondylar eminence.
Functional Anatomy of the Craniomedial and
Caudolateral Bundles of the Cranial Cruciate
Ligament in Beagle Dogs
Koji Tanegashima 2019
craniomedial bundle (CrMB) and caudolateral bundle (CdLB)
The area of the
CrMB on the femoral and tibial attachment sites was larger than that of the CdLB.
During stifle range of motion, each divided fibre bundle in the CrMB and CdLB was twisted intricately. The tension of the CrMB was higher than that of CdLB. The central part of the CrMB was always tense during stifle range of motion.
when the stifle jointwas
extended in the present study, both bundles were tense, and
when flexed, itwas objectively confirmed that only the CrMB
was tense.
changes in tension in the entire CrCL and the entire CrMB
were similar with no significance, and the areas of femoral
and tibial attachment sites of the CrMB tended to be larger
than those of the CdLB, suggesting that the CrMB greatly
contributes to themaintenance of tension in the CrCL in dogs
Prevalence, Risk Factors and Outcome of Postoperative
Tibial Tuberosity Fractures in Dogs Undergoing Triple
Tibial Osteotomy Surgery
Benito de la Puerta 2019
retrospective, 100 dogs (113 limbs)
tibial tuberosity fracture was identified in 25/113 stifles (22%)
fracture within 6 weeks of surgery was postoperative cortical hinge width (CHW) of 5.5 mm cut-off value
in TTO relative contribution of the tibial tuberosity advancement to the total
CA is 33%,
None of the dogs that developed postoperative tibial tuberosity fracture in this study had repeat surgery
narrowCHWat the distal cortical attachment of the tibial crest had a strong association with the development of postoperative tibial tuberosity fracture
31 fissures were recorded on the
immediate postoperative radiographs, but only 4 developed
a tibial tuberosity fracture
Patients that developed tibial tuberosity fracture and were conservatively managed did not have a worse
clinical outcome than patients that did not develop tibial tuberosity fracture
recommended: severe lameness at presentation or a major displacement of the tibia tuberosity may warrant a surgical intervention.
tension band wire could be used in patients with a thin CHW or as part of the technique to decrease the risk
In studies of tibia plateau levelling
osteotomy surgery, owner satisfactionwas reported to be 93
to 95%.19–22 In studies of tibia tuberosity advancement
surgery, owner satisfactionwas reported to be 90 to 92%.
Modified Triple Tibial Osteotomy for Combined Cranial Cruciate Ligament Rupture, Tibial Deformities, or Patellar Luxation
Livet 2019
9 dogs, retrospective
Perioperative distal tibial crest fracture was treated by pins and a figure-of-eight tension-band wire in five dogs (55.6%). One major (surgical site
infection) and three minor postoperative complications were observed. At the last follow-up, seven dogs (77.8%) had no
lameness
Finally, it is difficult to know if the mMPTA correction was indicated in these cases
good-to excellent owner satisfaction.
Cranial cruciate ligament rupture, tibial deformities, and medial patellar luxation are difficult
to treat together. A modified TTO may be used to treat these conditions.
TTO complication rate is comparable to those obtained using TPLO and TTA
(23–36%), and the most common complication is a fracture
through the distal end of the tibial crest osteotomy (23.4%).
location of the
medial closing wedge was directly linked to the cranio-caudal wedge
and was not based on the Center of Rotation of Angulation of the
tibial deformity. This could lead to postoperative deformities and axis
translation.
weh et al: TPLO with wedge postoperative surgical complications
were documented in 21% of the cases, and all complications were
considered major because they necessitated additional surgery
TPLO and tibial tuberosity
transposition (TTT) was used to treat CrCL rupture combined with
medial patellar luxation (MPL). No catastrophic or major postoperative
complications occurred
Novel crescentic, medial-closing, medially translating, centre-of-rotation-ofangulation-
based, levelling osteotomy for lateral compartment stifle disease
with partial cranial cruciate ligament tear in two dogs
Cashmore 2024
3 and 5yr followup, needle arthroscopy
lateral compartment
disease of the canine stifle, characterised by articular
cartilage lesions of the lateral femoral condyle and
tibial articular surface with meniscal injury, is an infrequently
reported
Boxers are reportedly over-represented,
loss of meniscal function in lateral compartments results in a 145% increase in peak contact forces
Proximal tibial valgus has been associated
with an overload of the lateral compartment
High tibial osteotomy
(HTO) is a common procedure in human orthopaedics
for the treatment of uni-compartmental cartilage degeneration in the femorotibial joint
reduced pressure in the lateral stifle compartment
by shifting the mechanical axis of the stifle
medially. Although biomechanical testing is needed
to prove this
CBLO allows translation and angulation
without altering the relationship between the patellar
tendon insertion and stifle joint surfaces, which may
reduce the risk of iatrogenic patellar luxation.
reported association of synovitis and
CrCL degeneration, a levelling osteotomy was performed
to reduce CrCL strain (Hayashi
Diagnosis of medial meniscal lesions in the canine
stifle using multidetector computed tomographic
positive-contrast arthrography
Knudsen 2024
Prospective case series.
Study population: Client-owned dogs (n = 55)
Sensitivity for identifying
meniscal lesions was 0.62–1.00 and specificity was 0.70–0.96. Intraobserver
agreement was 0.50–0.78, and interobserver agreement was 0.47–0.83
Diagnostic performance was suitable for identifying meniscal
lesions. An effect of experience and learning was seen in this study.
MRI, with a diagnostic accuracy of
86%–91% and sensitivity and specificity for medial meniscal
tears of 91%–93% and 81%–88%, respectively
A mismatch of planning and achieved tibial plateau angle
in cranial closing wedge surgery: An in silico and clinical
evaluation of 100 cases
Banks 2024
determine whether Oxley’s modified cranial closing wedge
osteotomy (CCWO) results in a tibial plateau angle (TPA) of 5
retrospective radiographic in silico study.
Sample population: A total of 100 stifle radiographs;
Oxley’s modified CCWO did not result in TPA of 5 in most
cases. Ostectomy distalization exacerbated under-correction.
Caudal pole meniscectomy through an arthroscopic
caudomedial portal in dogs: A cadaveric study
Keider 2024
pozzi
Experimental ex-vivo study.
Sample population: Ten cadaveric
The mean iatrogenic articular cartilage injury (IACI) was 3.71 ± 1.78% of the
area of the medial meniscus.
Conclusion: The establishment of a caudomedial portal for CPM in canine
cadavers was feasible and allowed to perform a partial caudal pole meniscectomy.
iatrogenic injuries to MCL and caudal
cruciate ligament in this cadaveric study, surgeons
should be aware of the potential risk for these injuries
Our results
emphasize that a minimally invasive procedure such as
arthroscopy is not without risks and strategies including
joint distraction and use of small diameter instruments
should be considered when the joint is too narrow.
Long-term radiographic appearance of a bioabsorbable
biocomposite tibial tuberosity advancement cage implant
CL Ferrell 2024
AVJ
1 year after implantation.
Design Retrospective case series
A biocomposite tibial tuberosity advancement cage
was found to have variable amounts of radiographically apparent
osseous integration at least 1 year after implantation.
Radiographically, these implants appear to
show changes in optical density relative to implant integration as it
is degraded with accompanying bone ingrowth.7,13 They initially are
described as being easily distinguishable from surrounding bone with
whitening of the edges seen as calcium deposition and callus formation
occurs. As this progresses, a cloudy bone formation ensues,
which slowly decreases the visibility of the implant until the material
is indistinguishable from surrounding bone
Effect of Plate Type on Tibial Plateau Levelling
and Medialization Osteotomy for Treatment of
Cranial Cruciate Ligament Rupture and
Concomitant Medial Patellar Luxation in Small
Breed Dogs: An In Vitro Study
Dallag 2023
The þ4mm and þ6mm offset Fixin plates may be considered for TPLO-M
in dogs weighing between 5 and 10 kg. The þ6mm offset plate should be used
cautiously in dogs weighing less than 10 kg since this plate may result in insufficient
postoperative bone apposition at the osteotomy site.
increased in plate to bone distance, which may result in
weakening of the bone-plate construct
Medialization of the tibial plateau resulted in a small but not
significant change in mMPTAvalues inmost of the study groups.
