Ch 60 Femur fracture Flashcards
femure fractures
- 20% to 25% of all fractures encountered in the dog and cat
- Young animals are significantly overrepresented
- involving the proximal and distal physes occur most commonly in immature animals
- most closed likely because of the protective effects of the large thigh musculature
- historically porgnosis guarded > likely due to older tehcniques, less biological approach, inappropriate implants
- prognosis dependent on fracture severity, articular involvement, soft tissue trauma, and concurrent injury.
- reported to be the most common affected by osteomyelitis and nonunion
- frequently associated with severe trauma > assess for shock and injuries involving the thoracic or abdominal cavity
biological osteosynthesis stresses the importance of reducing iatrogenic trauma to the fracture site through less precise fracture reconstruction (except for articular fractures) and less rigid fixation.
- Its effect is optimization of biologic potential, which encourages early formation of callus with rapid secondary bone healing.
- In parallel, implant evolution has included improvements in plate and interlocking nail technology to provide greater strength, as well as better preservation of blood supply.
Describe the AO fracture classification system
Arbeitsgemeinschaft für Osteosynthesefragen
Each bone has a number (femur = 3)
Second number denoted relative position of the fracture within the bone
- 1 = proximal
- 2 = shaft
- 3 = distal
Described with respect to its morphology
- A = Single fracture
- B = Wedge or butterfly
- C = Complex
Final number corresponding to severity and prognosis
- 1 = good to excellent
- 2 = moderate severity, guarded to good prognosis
- 3 = severe, guarded to poor prognosis
femur is composed of three separate regions?
(1) The proximal region
- head
- neck,
- trochanters
- trochanteric fossa
(2) the diaphysis is the elongated, cylindrical region of cortical bone, bordered by the proximal and distal metaphyses
(3) the distal region
- distal metaphysis or supracondylar
- trochlea
- condyles
- intercondylar fossa.
What are the main forms of proximal intracapsular fractures? (4)
- epiphyseal
- physeal
- subcapital
- transcervical
What are the main forms of proximal Extracapsular fractures? (3)
- basilar neck
- intertrochanteric
- subtrochanteric
Fractures of the distal region of the femur (3)
- supracondylar (metaphyseal fractures)
- physeal
- condylar and intercondylar (epiphyseal fractures)»_space; bi or unicondylar
muscle pull from the gastrocnemius, semitendinosus, and semimembranosus muscles results in caudal displacement of the distal fracture segment
Radiographic Assessment of the Femur
- Orthogonal radiographs
- A magnification marker is required due to magnification
- standard VD: femoral axis inclination is in excess of 35 degrees to the radiology table, which causes distortion of the entire femur (shortening)
- craniocaudal radiograph: via an extended ventrodorsal or horizontal beam projection
- semi-flexed position (“frog-leg”) beneficial for assessing the proximal region of the femur
- Adequacy of positioning by referencing the femoral trochlear ridges and intercondylar fossa rather than using the fabellae position, which is inconsistent between patients
- Given the limitations of rads, more detailed imaging via (CT) should be considered
Anatomy of the Femoral Head and Neck
- covered with hyaline cartilage, except over the fovea capitis,
- lateralization of femur provides hip joint with a greater ROM, but generates large bending stresses > The trabecular network is naturally oriented to withstand these forces
- reinforced cranially by an osseous ridge that extends from the base of the femoral head to the greater trochanter
- head and the proximal portion of the neck are within the capsule of the hip joint
- anatomic relationship between the femoral head and the diaphysis is characterized by the angles of inclination and anteversion
Where is the highest strain density observed in the femoral neck?
Most medial and distal portion
What is the normal angle of inclination?
130 - 145 degrees
in the frontal plane
What is the normal angle of anteversion?
27 - 32 degrees
in the transverse plane
Anatomy of the Trochanters and Trochanteric Fossa
- proximal femur contains three protuberances: greater, lesser and third
- trochanteric fossa: attachment site of internal and external obturator muscles and the gemelli muscle.
- The capital physis is L-shaped, which provides intrinsic resistance to shear and rotational forces
What muscles attach to the greater trochanter?
the lesser trochanter?
the third trochanter?
greater:
- Middle gluteal
- deep gluteal
- Piriformis muscles
Lesser:
- Iliopsoas
Third:
- superficial gluteal muscle
What muscle attach at the intertrochanteric fossa?
Internal and external obturator
Gemelli
What are the three subdivision of the proximal blood supply?
What does each subdivision include?
Extraosseous
- lateral and medial circumflex femoral arteries
- caudal and cranial gluteal arteries
- iliolumbar artery
- gluteal and circumflex arteries anastomose to form vascular ring at base of femoral neck
- medial circumflex branches to give nutrient a.
Intracapsular
- Arise from vascular ring, penetrate joint capsule at distal attachment and course subsynovially along craniodistal femoral neck
- Anastomose near capital physis to form intracapsule vascular ring
- Branches off ring penetrate the physis and give rise to intraosseous arcuate network
Intraosseous
- Branches of caudal gluteal and medial circumflex penetrate the floor of the trochanteric fossa and create intraosseous network
In dogs, the artery of the ligament of the head of the femur does NOT contribute to epiphyseal blood supply. This is in contrast to the cat
Disruption of vascular network may account for complications such as:
(1) abnormal development of the femoral head and neck,
(2) femoral head and neck resorption
(3) degenerative joint disease
all arteries of the intracapsular and intraosseous networks propagate from the extraosseous vessels > blood supply highly susceptible to vascular insult
How much of the femoral longitudinal growth is from the femoral capital physis and the trochanteric physis?
At what age do they close?
- Capital physis 25%
- Trochanteric physis 0% (involved more with shape)
- Closure in dogs begins at 6 months, complete 9-12m
- Closure in cats 7-10m
proximal physis normal and fracture
Open Approaches to the Proximal Region of the Femur
- the craniolateral approach
- the dorsal approach via osteotomy of the greater trochanter (Gorman approach),
- the dorsal approach via tenotomy of the gluteal muscles - only in immature animals
Gentle tissue-handling skills and preservation of the vasculature must be applied > trauma to gluteal or circumflex vessles supplying the extracapsular vascular ring
Minimally Invasive Approach to the Proximal Region of the Femur
reduce iatrogenic injury to articular surface and the vascular network of the proximal end of the femur
- requires the use of intraoperative fluoroscopy > ideally standard sized c-arm
- disadvantages of mini C-arms are the inability to provide high-quality images in larger patients and diminished clearance
- minimize personnel exposure to levels as low as reasonably achievable (ALARA)
Stabilization of Fractures of the Proximal Region of the Femur
- account for approximately 25% of all fractures
- conservative management is not considered a suitable option, and early surgical intervention is recommended
- Surgical options broadly categorized as primary repair or salvage procedures.
- Primary repair = gold standard, associated with good functional recovery and limited risk for complications.
- conversion to a salvage procedure can be performed > THR or FHNE
- animal’s age, duration between the inciting trauma and treatment, and fracture location
- Prognosis varies from guarded to excellent
- preexisting OA contraindication for primary repair
(5) unique biologic and mechanical features of proximal femoral fractures which can make it challenging
- Concurrent trauma to fragile vascular network
- Residual growth potential of capital physis
- Eccentric loading of femoral head
- limited bone stock for stabilisation
- potential articular surface involvement
Fractures of the Capital Epiphysis
- associated with Coxa plana (flattening of the femoral head epiphysis) and luxation
- Ventral approach: Avoids requirement to transect ligament of the head of the femur which can contribute to instability
- Smaller fragments not amenable to fixation are excised
- large fragment, stabilization with Kirschner wires, small-diameter screws in lag fashion
- a minimum of two implants should be used to resist rotational forces,
- implants must be countersunk
- prevention of postoperative luxation often required: prosthetic joint capsule or an iliotrochanteric band, toggle if ligament gone.
- immature animals: lagged screw(s), associated with premature physeal closure, resorption of the femoral neck, and degenerative changes
Fractures of the Capital Physis
- Salter-Harris type I fractures most common
- Salter-Harris type II fractures often present with femoral head luxation with the epiphyseal fragment remaining attached to the ligament
- Type III and type IV fracture are reportedly more challenging to diagnose and repair
- delay in reduction and stabilization allows for ongoing trauma to vasculature and physeal surfaces.
- Reduction and internal fixation of fractures of the capital physis can be achieved using an open or closed approach (iatrogenic trauma to the vascular network is minimized)
- pins/wire to prevent compression and iatrogenic closure of the physis
- presumed, however, that regardless of the implant, the physis may close as a result of the inciting or surgical trauma
How often is concurrent seperation of the trochanteric physis seen with capital physeal fractures?
11 - 15%
What sized K-wires are appropriate for cats and most small-medium dogs?
How many should be placed?
In what orientation?
- 0.7 - 1.6mm diameter
- minimim of 2 pins, no more than 3
- Pin should be parallel to each other (allows continued growth of physis, allows forces to be distributed equally between pins, normal loading of growth plate and dynamic compression of the fracture)
- 2 pins shown to be as strong as intach femoral neck in one study (weaker in another).
- Addition of a third pin increases strength by 29%
- Pins can be placed normograde or retrograde. Normograde, distal-to-proximal direction, is the least invasive
- facilitated by the use of a C-shaped drill guide (which may be quite traumatic to place)
- Only after anatomic reduction is achieved are the pins advanced and secured within the proximal segment.
- insertion point is located caudal and distal to the greater trochanter within the subtrochanteric region
resist shear and rotational forces
Fluoroscopically guided placement
- pins should be advanced as deeply as possible within epiphysis, However, if extend through cartilage > OA
- hemispheric contour creates a challenge for accurate pin position
- Fluoroscopy ideal because it allows to verify pins embedded within the subchondral bone
- CARE: tip of a fixation pin could appear safely embedded on a single 2D fluoroscopic view
- avoid iatrogenic articular lesions, pin placement should be verified on no fewer than two fluoroscopic projections
- surgeon remain attentive to the haptic feedback while gently and slowly advancing the pin(s
What structures can be used to guide epiphyseal femoral head pin placement?
- epiphyseal thickness can be estimated with the use of standard radiographs
- Pins located within the center of the epiphysis can be safetly advanced a distance equal to 75-80% of the contralateral epiphysis or width of the pubic bone
- Eccentrically placed should only be advanced to 65%
alternatively, one may purposely advance the pins until they can be seen or palpated at the articular cartilage with a blunt instrument
complications
dysplasia, osteoarthritis, or the “apple core”
salvage for physis #
FHNE
- profound changes in proximal femoral anatomy and subsequent loss of function may occur with femoral head and neck excision in young animals
- altered weight bearing, disuse muscle atrophy, lameness after exercise, and ankylosis.
- Early and aggressive postoperative rehabilitation is required
THR
- posible with cementless
- however, concerns regarding the size of the implant used, with respect to the animal’s size at skeletal maturity, have arisen
What percentage of dogs are reported to have a moderate to poor outcome after a FHO?
20%
Capital Physeal Dysplasia
- definitive cause remains unknown
- early neutering has been shown to delay physeal closure and is potentially related to physeal dysplasia
- unilateral and bilateral
- Histopathology in cats: intact epiphysis with an unusually wide physis containing irregular clusters of chondrocytes in an abundant extracellular matrix and necrotic cartilage at the cleavage site
Tx
- fixation using a screw in lag fashion (growth is complete).
- To limit any loss in reduction as the screw engages the epiphysis, an antirotational Kirschner wire can be placed
- MIO with fluoro
- salvage: FHNE or THR
What is capital physeal dysplasia?
What animals are overrepresented?
- Spontaneous seperation of the capital physis in animals after timely physeal closure
- Young, overweight, castrated-males cats overrepresented
Fractures of the femoral neck
- common in dogs and cats younger than 1 year of age.
- intracapsular (subcapital or transcervical) or extracapsular (basilar)
- closed and open reduction
- difficult to treat > lack of intrinsic stability and the presence of substantial bending moments
- Kirschner wires, small-diameter Steinmann pins, and bone screws
- multiple pins recommended in immature patients to prevent premature physeal closure
- mature patient: fixation with a screw in lag fashion was significantly stronger and provided greater interfragmentary compression compared to multiple pinning techniques > beneficial in large- and giant-breed dogs.
What fracture plane minimised shear stresses of femoral neck fractures?
30 degrees or less to the transverse place
greater shear forces are associated with a greater incidence of implant failure and nonunion
Fractures of the Greater Trochanter
- typically Salter-Harris type I fractures that occur as avulsion fractures in immature animals
- frequently occur with ipsilateral fracture of the capital physis or neck
- considerably displaced, conservative treatment is not recommended because malunion and altered development of the proximal femur may result
- all pins and screws are placed perpendicular to the physis and parallel to each other
- premature closure of the trochanteric physis is likely > not affect the longitudinal length, changes in conformation of the proximal region may alter hip joint biomechanics and predispose these dogs to DJD
What are the repair options of fractures of the greater trochanter?
What are the potential results of premature trochanteric physeal closure?
Repair
- Conservative if minimally displaced
- Pins and tension band
Results in early physeal closure
- 5 deg increase in both inclination and anteversion
Subtrochanteric Fractures
- proximal metaphysis and that are distal to the trochanters
- Reduction via combined craniolateral approach to the hip and lateral approach to the diaphysis
- ORIF but with principles of biologic osteosynthesis applied when possible.
- bone plating typical (+/- IM pin for bending forces)
- due to the limited bone stock available proximally, ILN may be more effective (contraindicated if concurrent transcervical fracture present)
- ILN: bolts should be directed slightly caudolateral-to-craniomedial direction, parallel to the femoral neck, increase bone stock and avoid fossa
- Precise contouring and positioning of the plate over the lateral aspect of the greater trochanter is important
- transcervical screw optimize the stability of the proximal fragment
- Tied-in ESF has increased morbidity > predisposing the animal to contracture of the quadriceps
angle stable ILN better resists bending
What is essential in providing stability of the proximal fragment of a subtrochanteric fracture when using a bone plate?
Transcervical screw
What is the reported rate of femoral neck resorption after open reduction and internal fixation?
What thought to be responsible for this complication? (2)
apple core
Up to 70% within 3-6 weeks
Disruption of the vascular network and overfixation, resulting in vascular disruption and stress protection
Subsequent collapse is rare
Why are pins for femoral neck/capital physeal fractures recommended to be removed? (4)
- Allows remodelling and more complete healing
- Decreased interference with residual growth
- Eases revision options if sevre OA develops
- May help to reduce the risk of neck resorption
advantages of MIO of femoral neck #?
- limited soft tissue trauma
- optimal preservation of blood supply
- promote rapid healing (2 and 3 weeks after surgery)
- resorption and segmental collapse of the femoral neck is not reported
- NOT eliminate risk of proximal femoral dysplasia and secondary osteoarthritis
common error is to initiate insertion of pins too far proximally on the craniolateral femoral cortex
post-op and outcomes
post-op
- ensure appropriate alignment and implant placement with rads
- activity restriction, including cage confinement, may be required until clinical union
- physical rehabilitation, particularly in immature animals, should be implemented as early as tolerated
outcome
- following internal fixation reported to be good to excellent in multiple retrospective studies
- depending on several factors: The animal’s age (if physis affected), Preexisting hip dysplasia, severity of the inciting trauma, articular causes OA (which may require future intervension)
- type of open surgical approach used nor the duration between the time of injury and the time of primary fixation shown to be significantly associated with prognosis
- (MIO) compared with open approaches: unknown benefit, technically challenging
salvage procedures
- indications: (1) preexisting hip dysplasia/OA (2) highly comminuted fractures (3) chronic fractures (4) when revision is required
- FHNE
- THR (contrindicted: infection)
complications (9)
- premature physeal closure,
- resorption of the femoral neck (frequently observed following ORIF) clinical relevence limited
- inadequate reduction and malunion
- altered development of the hip joint with subsequent osteoarthritis
- implant failure,
- implant migration,
- nonunion,
- sciatic neurapraxia,
- infection
Most of the femoral diaphysis lacks muscular attachment except for the proximal and caudal surfaces. What muscles are attached?
Subtrochanteric region
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
- Adductor longus
Caudal surface
- Adductor magnus et brevis (allow the narrow facies aspera / linea aspera)
- Pectineus and semimenbranosus on distal 1/3 caudomedially
Open Approaches to the Shaft of the Femur
- incision in the superficial leaf of the fascia lata (cranial tobiceps femoris muscle)
- Retraction of the biceps femoris caudally and vastus lateralis cranially
- then incise through aponeurtic lead of facia lata to expose shaft
- Proximally, the origin of the vastus lateralis muscle may be elevated for exposure of the subtrochanteric region
feline
- larger gluteal muscles
- caudofemorlis muscle > between superficial gluteal and biceps femoris
- origin of vastus lateralis strong insersion along most of shaft > must be sharply incised
Minimally Invasive Approach for Repair of Fractures of the Femoral Diaphysis
- proximal: greater trochanter to expose the intertrochanteric crest by caudal retraction of biceps femoris and cranial retraction of vastus lateralis.
- Distally, supratrochlear aspect of the femur exposed through lateral parapatellar arthrotomy
Bone Plates
- applied on the tension surface of a bone
- DCP > rigid fixation and interfragmentary compression > stability and primary bone healing
- morphological analysis showed variation for twisting and bending of lateral surface > precise contouring of the plates requires significant twisting and bending
- ## biologic osteosynthesis overcome ORIF > better preservation of the fracture’s biologic environment, and faster healing
Plate-Rod Constructs
- rod beneficial in facilitating reduction and restoring alignment
- normograde insertion proximal-to-distal recommended for more accurate positioning at trochanteric fossa
- retrograde associated with greater risk of sciatic nerve injury, particularly cats
- caudal curvature of the distal end in dogs, slight overreduction needed (therefore anatomic recon NOT possible) cats have a straighter femur and the rod is easily embedded within the distal metaphysis
- rod fills approximately 35% to 40%
- DCP plate: minimum 4x cortices engaged within the proximal and distal fragment
Intramedullary Rod (Pin) and Cerclage Wires
- treatment of simple long oblique, spiral, and butterfly fractures
- requires anatomic recon + approriate technique to be success
- relies on the rod to resist bending
- cerclage wires counteract rotational and compressive via interfragmentary compression
- fracture length should be 2-3x diameter of the bone
- two (preferably double-loop) cerclage wires to withstand bending and shear forces along fracture line
- contraindicated in immature animals
Stack pinning is associated with complication rates as high as 50%
Interlocking Nails
over reduction distal end 12 degree
- nail is locked in place via solid bolts, that engage both cortices and the nail
- 3 to 10 mm in diameter
- mechanical and biologic advantages:
- Compared with plates, ILN have larger and more uniform area moment of inertia, which allows them to resist bending
- near the neutral axis of the bone acts synergistically to shield the device from deleterious bending moments
- resist rotational and compressive forces via their locking bone screws or bolts
- suited for implementation of biologic osteosynthesis
- intraoperative fluoroscopy for verifying accurate placement of locking devices and encourage MIO reduction of #
- nails can be used in a static (bolts proximal and distal to the fracture) or dynamic mode (bolts on one side of the fracture only)
- old style: absence of a rigid mechanical interlock between the nail and the locking device results in instability in rotation and bending (slack)
- angle-stable: eliminating both torsional and bending slack Due to the rigid, fixed relationship between the nail and its locking bolts (a true intramedullary fixator)
- in vivo: faster healing times and stronger and more formation of mature callus over time
Minimally Invasive Fracture Repair of the Femoral Diaphysis
- intraop fluoro or by referencing specific anatomic landmarks proximally and distally for alignment of the fracture
- intramedullary (IM pin) or ‘indirect reduction system’ devices (or temporary ESF) eases restoration and maintenance of axial alignment while permitting adjustments in rotational alignment
- pull of the intrinsic external hip rotator muscles induces an external rotation of the proximal segment
- bridging fixation with interlocking nails and bone plates
Predisposing factors to the development of contracture of the quadriceps femoris muscle? (5)
- skeletally immature animals,
- exuberant bony callus,
- extended coaptation,
- muscular trauma
- infection
Extensive soft tissue manipulation associated with large, open approaches and suboptimal fixation techniques likely also contribute
poor prognosis; thus, early intervention is necessary
Implant removal, revision surgery, and/or aggressive physical therapy
Anatomy of the Distal Region of the Femur
- supracondylar region, including the supracondylar tuberosities and epicondyles
- two condyles (epiphyseal projections) form weight-bearing surface and are covered by articular cartilage
- separated by the intercondylar fossa caudodistally and continuous with the trochlear groove cranially
- proximal two-thirds of the groove is concave and is bound by the trochlear ridges
- Each condyle articulates with the associated meniscus and to the corresponding tibial condyle
- intercondylar fossa is the femoral attachment site of the cranial (lateral) and caudal (medial) cruciate ligaments
- chondrodystrophic breeds: elongated and caudally oriented with respect to the diaphysis > likely generates greater bending moments, may predispose to supracondylar, and condylar, fractures.
What muscles and ligaments attach to the supracondylar region of the femur? (5)
- Medial and lateral heads of the gastrocnemius (from caudally located supracondylar tuberosities)
- Superficial digital flexor muscle
- Collateral ligaments (epicondyle)
- Popliteus (lateral condyle)
- Long digital extensor muscle (Between lateral epicondyle and lateral ridge of trochlear groove
How is the distal physis shaped?
When does it closed?
- 4 pyramidal grooves which interdigitate with 4 similarly shaped epiphyseal pegs (provides intrinsic resistance to rotational and shear forces during growth)
- Closure in dogs begins at 6m, complete 9-12m
- Closure in cats begins 4m, completel 7-9m
distal physis is responsible for approximately 75% of the longitudinal growth
Open Approaches to the Distal Region of the Femur
- lateral, medial, or combined approach through the same skin incision
- stifle arthrotomy
- osteotomy of tubial tuberosity: only for severely comminuted articular fractures
Interlocking Nails
- if sufficient bone stock is present for engagement of at least one of the two locking bolts
- distal tip of the nail should be advanced to the level of the Blumensaat’s line
- Shortening of the tip of the interlocking nail may be recommended to facilitate deep seating of the nail
- tip of the nail may protrude through the femoral trochlea immediately proximal and cranial to the femoral attachment of the caudal cruciate ligament
Pin Fixation of the Distal Physis
- Despite the stability regained by anatomic reduction, the strength of the physeal interdigitations not sufficient to counteract shear and rotational forces
- two pins required for sufficient stability
- normograde insertion in a distal-to-proximal direction
- cross-pinning, the lateral pin is inserted just caudal and distal to the tendon of origin of the long digital extensor muscle, at approximately a 30- to 45-degree angle
- similarly positioned pin is placed from the medial surface of the condyle.
- appropriate angle so their crossover point is optimally located proximal to the fracture line, penetrate transcortex for stability
- effective at neutralizing the forces across the physis
- Rush pinning (dynamic pinning) long, smaller diameter Kirschner wires are inserted at a steeper angle of 15 to 20 degrees
Unicondylar Fractures
- involve an articular surface, repair must include anatomic reconstruction, rigid fixation, and an early return to controlled activity
- collateral and cruciate ligaments, as well as the menisci should be carefully assessed
- more common in mature animals
- medial condyle is more frequently affected
- stress radiographs in varus or valgus may ID minimally displaced fractures
- open or closed approach
- multiple divergent pins, screws placed in lag fashion or a combination of these
- screw is inserted so as to avoid the condylar fossa and subsequent damage to the cruciate ligaments.
bicondylar
- frequently associated with severe soft tissue trauma, particularly cruciate ligaments and menisci
- CT recommended
- open approach is recommended
- first, transcondylar screw +/- more screws to reconstruct condyle
- second, fracture line involving the supracondylar or physeal regions must be stabilized > interfragmentary screws +/- cross-pins +/- buttress plate(s)
- bone plate fixation is most effective in restoring the functional axis of the femur
- SOP plates on the craniomedial and craniolateral aspects
- limit the risk of long-term complications due to implant interference with patellar tracking, plate removal recommended
washers increase screw-head force distribution and avoid cortical damage during screw tightening
Stabilisation of femoral capital physeal fractures using transcervical pinning in cats: 19 cases (2014-2022)
De Vreught 2024
retrospective
owner questionnaire for long-term follow-up.
Nineteen cats
all open approach, Two 1.0-to 1.2-mm
diameter K-wires
Proximal femoral epiphysis to femoral neck ratio high > thinner femoral neck on the affected side
male neutered, maincoon 12x risk
15/19 cats no lameness at the 1-month Major 9.5% and catastrophic 23.8% complications occurred
All catastrophic complications occurred in fractures with a high preoperative osteolysis grade (2 or 3).
without histo, likely had cases of capital dysplasia
High rates of implant failure with loss of fracture reduction were observed in cats with high-grade preoperative osteolysis.
In other studies, the most affected cases were usually not considered eligible for surgical stabilisation, which could explain this
difference.
degree of bone lysis at 1 month seemed to remain stable, in contrast to a recent study using transcervical screws (Vink et al., 2022). This can be explained by the small diameter pins used.
FCPF makes assessing hip dysplasia
difficult, which is problematic because this condition could
decrease the functional prognosis when surgical stabilisation of
the fracture is considered.
Proposed Definitions and Criteria for Reporting Time Frame,
Outcome, and Complications For Clinical Orthopedic Studies
in Veterinary Medicine
James L. Cook
Subjective Clinical Outcomes
- Full function—restoration to, or maintenance of, full intended level and duration of activities and performance
from preinjury or predisease status (without medication).
- Acceptable function—restoration to, or maintenance of, intended activities and performance from preinjury or predisease status that is limited in level or duration and/or requires medication to achieve.
- Unacceptable function—all other outcomes.
Use of a Modified Intramedullary Pinning Technique for Distal Femoral Physeal Salter–Harris Type I and II Fracture Management: A Retrospective Study of 31 Cats
Bondonny 2024
an intramedullary pin via the intercondylar fossa, immediately cranial to the site of insertion of the caudal cruciate ligament and one antirotational pin inserted in the lateral femoral condyle
Bone healing was radiographically
confirmed 6 to 8 weeks postoperatively in all cases. The majority of cats (30/31) were
classified as full functional outcomes at mid-term follow-up. The overall mid-term
complication rate was 3% (1/31). Implant migration was not observed and implant
removal was not needed in any case.
pin 45% femur diameter
Short-term complications were noted in five fracture cases. Two were minor complications, with the development of a seroma onthe lateral aspect of the stifle joint, while major complications were present in three fracture cases.
one case inwhich a grade IV medial
patellar luxation associated with a valgus of the femoral distal extremity was reported.
distal femoral growth plate remains open
until the age of 12.4 to 17.5 months in cats
- growth plate appeared radiographically closed in 72.3%
of cases 6 to 8 weeks postoperatively
- aged 5 months or less at the time of surgery, radiographic closure
of the growth plate was noted in four cases (40%).
pros: not require lateral and medial joint dissection as per cross pinning
potential to elicit iatrogenic damage to intra-articular structures and to result in the development of unnecessary stifle osteoarthritis, difficutly removing the implant
various studies report migration or loosening of the implant, requiring a second procedure for removal in 8 to 14% of cases
Short-Term Clinical and Radiographic Outcome after Stabilization of Femoral Capital Physeal Fractures with
Cortical Positional Screws in 39 Cats
Vink 2022
retrospective
Forty-six fractures in 39 cats met the inclusion criteria.
surgery open approach
In 45/46 fractures, radiographic signs of bone healing were present and 35/39 cats were assessed as walking normally by a veterinarian at 6-week follow-up.
There was a significant increase in
radiographic signs of osteoarthritis and femoral neck osteolysis on 6-week follow-up radiographs.
Pre- and postoperative osteoarthritis and femoral neck osteolysis were not associated with clinical outcome
7/25 owners reported a gait abnormality in the short- to long-term (almost 30%)
Fractures with a high grade of osteoarthritis or femoral neck osteolysis visible on preoperative radiographs or during
surgery were not considered eligible for surgical stabilization.
no need to perform any revision
surgery or removal of implants in this study
Positional screws were chosen
over lag fashion because of the difficulty of drilling the gliding hole
screws is stronger than fixation
with Kirschner wires.
Kirschner wires are associated with
thermal necrosis29 andwe believe that thismight be a reason for a higher rate of complications (e.g. implant migration, infection).
in our experience placement of
screws in the femoral neck is subjectively easier
Some authors advise to use Kirschner wires over screws for fixation of physeal fractures to prevent iatrogenic closure of the physis
Preoperative osteolysis: metaphyseal femoral neck resorption preceding
slipped capital femoral epiphysis or it may be the result of chronic traumatic FCPF
Postoperative osteolysis: progressive metaphyseal femoral neck resorption, disruption of the blood supply or both.
67.4% of the fractures developed osteolysis of the femoral neck in this study
Management of Feline Femoral, Tibial and
Humeral Fractures Using a 3.5mm Titanium
Interlocking Nail
Mund 2023
Retrospective clinical study
non-angle-stable titanium interlocking nail
Complications occurred in 11/67 fractures (16%). Major complications occurred in 8/67 fractures and included screw breakage , nail breakage, nail bending , screw loosening ,non-union. Statistical analysis showed a significant difference between fracture types and the occurrence of major complications
7/8 complications occured in femur
In 25/67 fractures, technical difficulties arose during nail application. These included nail breakage in the proximal screw hole (1/67) and incorrect drilling with the drill bit
missing the screw hole of the interlocking nail in 24/67 cases
occurrence of major complications was greater in transverse fractures than in oblique and comminuted fractures
> > cause for an increased complication
rate of transverse fractures might be explained by the slack phenomenon after interlocking nail application.30 This leads to micromovement around the fracture gap and prevents or at least slows down primary bone healing, which is an important factor in transverse fracture healing > transverse fractures need a rigid fixation and absolute stability to avoid interfragmentary strain.
reduced slack in angle stable
complication rate between 6.6 and
23.5% and a revision rate up to 14.28% of fractures reported
A common intraoperative complication is the malpositioning of screws. This is reported in 0 to 37.5% of cats or in 0 to 5.26% of
screws.Themost distal screw holes are commonly affected.
nail break: Common causes are an
insufficient nail diameter or positioning of the screw holes in or too close to the fracture gap acting as a predetermined
breaking point. A minimum distance of at least 10mm between screws and fracture gap is recommended
The use of a trocar shaped pin for scoring the bone before drilling reduces the slippage of the drill and potentially improves the occurrence rate
In cases where using two screws per fragment is not feasible, consideration must be given to use screws with larger core diameter or bolts or additional stabilization with a type 1a external fixator.
predisposition for screw breakage in the proximal fragment due to high bending loads in femoral fractures
cats with nail breakage, the distance between fracture gap and screws was less than 10mm, predisposing these cases to
failure. Material properties could be another reason. Titanium may be less resistent to single, high load
Comparison of three radiographic
assessment methods for detecting
slipped capital femoral epiphyses
in cats: Klein’s line, modified Klein’s
line and the S-sign
Butts 2023
The S-sign in both VD extended-leg and VD frog-leg views successfully detected
SCFE in cats and can be used to increase early diagnosis and treatment in cats with SCFE that have only subtle
radiographic changes
Closed reduction and fluoroscopic-guided percutaneous pinning of femoral capital physeal or neck fractures:
Thirteen fractures in 11 dogs
de Moya 2023
Retrospective case series
Satisfactory fracture healing and limb function achieved in 10/13 femurs (77%)
Complications occurred in 5/11 (45%)
cases and included intra-articular implants, implant failure/nonunion, implant
migration (2), and malunion. Of these five complications, two resolved with
implant removal, and a salvage procedure was recommended in the remaining
cases (2 were chronic #).
potential catastrophic clinical consequence of intra-articular pin penetration.
In a retrospective study investigating
outcomes of closed reduction and physeal fractures repair with this technique in small animals, excellent functional outcome was reported in 92% of cases, most of which had minimal fracture displacement preoperatively. Of the 42 physeal fracture repairs included in the study, only one femoral
plan an elective pin removal in dogs that
are less than 8 months of age at the time of injury to potentially reduce the risk of premature physeal closure.
Postoperative femoral neck resorption was minimal and noted in only two of 10 dogs
- single extracapsular vascular ring at the level of the femoral neck gives rise to the intracapsular and intraosseous network of vessels supplying the joint capsule, physis, femoral neck and epiphysis
humans investigating physeal fractures in adolescents showed that severity of preoperative radiographic displacement was associated with an increase in the risk of developing complications,
A recent study comparing fluoroscopy, CT and direct anatomic measurements of screw positioning in a cadaveric slipped capital femoral epiphysis model revealed that fluoroscopy and CT measurements overestimated the distance between the screw tip and the articular surface when compared to direct measurement
small, short-term, not objective, no control
Minimally invasive plate osteosynthesis of femoral fractures with 3D-printed bone models and custom surgical guides: A cadaveric study in dogs
Scheuermann 2023
Experimental cadaveric study.
Sample population: Seven dog cadavers
Femoral alignment was accurate when using plates precontoured to 3D printed models, regardless of reduction method (using IM pin vs new suture/bolt technique). There was no difference in length or alignment between reduction groups.
Clinical significance: Accurate plate contouring using anatomically accurate
models may improve fracture reduction accuracy during MIPO applications.
Custom surgical guides may reduce fluoroscopy use associated with MIPO.
» need clinical cases
precontoured plates based on
anatomic 3D-printed models, resulted in accurate femoral MIPO fracture reduction
In one clinical case series, immediate revision surgery was required in 10% of
femoral MIPO procedures performed without fluoroscopy.
Defining acceptable and unacceptable changes in femoral alignment after fracture
reduction and alignment warrants further research.
type II errors
Influence of Screw-Hole Defect Size on the
Biomechanical Properties of Feline Femora in an Ex Vivo Model
Hoon 2022
craniocaudal screw-hole defects of increasing diameter (intact, 1.5mm, 2.0mm, 2.4mm, 2.7mm), subjected to three-point bending and torsion to failure at two different loading rates.
Study Design Eighty femoral pairs
Defect size to bone diameter ratio was significantly different between defect
groups within bending and torsional experiments respectively. No significant differences in stiffness and load/torque-to-failure were noted with increasing deficit sizes in all loading conditions.
Screw-hole defects up to 2.7 mm did not significantly reduce feline bone
failure properties in this ex vivo femoral study. These findings support current screw size selection guidelines of up to 33% bone diameter as appropriate for use in feline
fracture osteosynthesis.
Defects up to a third of bone diameter
maintained at least 80% of intact bone strength, with no significant differences noted in all loading conditions
caution should be takenwhen extrapolating the current results of a single defect model, as multiple screw-holes are often created clinically.
Feline cortical bone has anecdotally been described as brittle, tending to fissure and shatter readily 25% bone diameter has been purported to avoid the risk of creating iatrogenic fractures (due to stress-riser)
femoral cadaveric study highlighted considerable interspecies differences in fracture properties due to variation in
bone composition, micro- and macro-structure
screwsize directs plate selection and influences its bending and pull-out strength
holes greater than 33% of bone diameter to avoid exceeding 50% strength loss
Biomechanical work has repeatedly shown
greater stiffness and strength of bone at increased loading rates, due to its viscoelastic properties
major limitation of this study involves the use of craniocaudal defects and bending despite most femoral flexural studies having the load applied mediolaterally
Simple ostectomy to address quadriceps impingement caused by distal femoral malunion in four dogs
Jones 2021
retrospective, 4 dogs, presented with femoral shortening and increased femoral procurvatum
objective gait analysis in three dogs revealed minimal to no lameness in two and mild residual lameness in one dog. Long-term radiographic analysis revealed fracture-site remodelling with an increase in femoral length
Using an oscillating saw, the protruding
bone was cut at approximately 45° to the long axis of the proximal
femur in the sagittal plane, with the osteotomy directed in
a cranio-proximal to caudo-distal direction
lack of a control group treated with an acute
limb realignment via a corrective osteotomy, precludes our ability to comment on superiority of one treatment over the other
well established that dogs with misalignment
in the frontal plane are less tolerant of conservative therapy and
require more complex surgical interventions
Three previous studies describe performing surgery to specifically address this sagittal plane deformity, by means of a caudal opening osteotomy (n = 1) or cranial closing wedge (n = 3) ostectomy
Interestingly, remodelling of the femur resulted in the reduction of the excessive procurvatum to very closely match the cranial bowing of the normal contralateral
side, with a subsequent return of normal stifle range of motion.
Effects of Femur Position on Radiographic
Assessment of Femoral Head and Neck
Excision Completeness in Cats
Howser 2020
20 femurs from adult cats. Complete FHNE was performed on 10 femurs and incomplete excision on the rest
Each femur was positioned through a predetermined set of eight radiographic views about the long axis
in external rotation (30° and 45°) had the
highest SE, SP and accuracy
Conclusions Evaluation of craniocaudal radiographic views with the femurs in
external rotation can increase the ability to assess the adequacy of the FHNE in cats
there are very few peer-reviewed
published reports regarding the outcomes of cats with FHNE. Reported outcomes following FHNE in cats are variable;
some studies have reported satisfactory to good outcomes, whereas others have reported inconsistent to poor outcomes.
study 66 dogs, 15 cats: revealed that functional results were rated as good in 38%,
satisfactory in 20% and poor in 42% despite a reported owner satisfaction of 96% with the procedure. Six of 12 cats had incomplete resection noted
