62. Stifle Flashcards
what attaches to the cranial and caudal intercondyloid areas
Cranial intercondyloid area—CrCL and cranial meniscal ligamentsCaudal intercondyloid area–caudal meniscal ligamentsCdCL attaches to the popliteal notch!
extensor groove
craniolateral surface of tibiapasses the long digital extensor tendoncranial notch–Tubercle of Gerdy (human)
3 main articulation in the stifle
- femorotibial–largest, main wt bearing2. femoropatellar3. tibiofibular
T/FThe infra patellar fat pad in the stifle is extrasynovial
TRUE
T/Fcruciate ligaments are extrasynovial
TRUEintra-articular (within the joint) but covered with synovium (extrasynovial)
attachments of the cruciate ligaments
CrCL—caudomedial aspect of the lateral femoral condyle and the caudolateral part of the intercondyloid fossa of the femur—attaches to the cranial intercondyloid area of the tibia2 PARTS: LARGE caudolateral, smaller craniomedial bands (axial spiral)CdCL: attaches to the lateral surface of the medial femoral condyle and runs caudodistally to attach to the medial aspect of the popliteal notch (Abaxial spiral)
hoops stress of meniscus
thick abaxially, thin axiallyradial forces caused during weight bearing are resisted by the tensile stress developed in the CIRCUMFERENTIALLY arranged collagen fibers
which meniscus has a meniscofemoral ligament
LATERALwhich “glides” more than medial meniscus–less likely to be injured1. meniscofemoral ligament2. lateral collateral ligament is NOT firmly attached3. popliteus muscle tendon is btwn mensicus and joint capsule
type of collagen for meniscus
fibrocartilage biphasic (solid phase and interstitial fluid phase)abundant type I cartilage3 layers to withstand compressive forcesdissipate forces radially (hoop stress)outter 2/3 CIRCUMFERENTIAL (tension)inner 1/3 RADIAL (compression)
blood supply to meniscus
peripherally–red-red zone is supplied by vascular synovium (15-25%)rest of meniscus is mostly Avascularaxially (center)–white-white zoneintermediate zone is red-white
normal flexion and extension stifle
flexion 41 degrees–laxity of LCLextension 162 degrees– collaterals taut
protective quadriceps mechanism during joint loading
during joint loading, there is increase strain in Cr CLsimulataneous contraction caudal thigh muscles and RELAX of quadriceps is PROTECTIVE for CrCL bc contraction of quadriceps increases strain on CrCL
two bands of the cranial cruciate ligament
craniomedial (smaller)-taut in both flexion and extexion PRIMARY CHECK caudolateral (LARGER)–taut in extension, lax in flexion; seconadry check
vital function of menisci
- load bearing (40-70%)2. load distribution (removal increases contact P)3. shock absorption (hoop stress)4. joint stability (maintains congruency)
T/Fremoval of the caudal horn of the medal meniscus causes HI focal pressure in the caudal region of the medial tibial condyle (>10mPA)
TRUEremoval of the caudal horn of the medal meniscus causes HI focal pressure likely contributing to the articular cartilage trauma post menisectomyincr P ~140%decr area 50%(similar changes with meniscal release caudal and mid body)
30 vs 75% partial menisectomies
30% radial width had minimal effects on biomechanics but partial menisectomies (75% radial width) and hemimenisectomies resulted in significant biomechanics changes
goal of meniscal release
eliminating the wedge effect of the caudal horn of the medial meniscus during femorotibial subluxationmidbody or meniscotibial ligament (caudal)still increase P 140% and decreases contact area by 50%
Slocum (TPLO) vs Tepic (TTA) theory of eliminating femorotibial subluxation in CrCL injury
Slocum TPLO: results in a joint force that is perpendicular to the tibial plateau; compressive force eliminates thrust(says joint force is parallel with tibia)Tepic TTA: results in a patellar ligament that is perpendicular to the tibial plateau to neutralize the cranial thrust force(says joint force is NOT parallel with tibia it is parallel with patellar ligament)
disorders of the CrCL
- avulsion (skeletaly immature, avulse from tibia more common–Sharpey’s fibers)2. acute rupture (trauma exceeds strength of ligament, mid substance minimal degeneration, most common in cats)3. progressive chronic degeneration (most common, age and BW >15kg)
what is epiphysiodesis
premature closure of growth plate (screw and/or divergent pins)for CrCL injury in young animals this may be helpful to prematurely close the cranial aspect of the proximal tibial physis and allow caudal growth to continue to reduce TPAmay decrease TPA 4 degrees; complications valgus
factors proposed to increase risk of degenerative CrCL
–increasing age (decr elasticity, incr chondroid metaplasia)–BW >15 kg–abN conformation (MPL, narrow IC notch, hi TPA, poor muscling)–neutering (timing is controversial)–immune mediated component–breed variation (Rotts, labs, WESTIES)–sex (females)
incidence of contralateral CrCL disease
37% in 17 monthsBuote et al Vet Surgery 200948% of Labs within 5.5 monthsTPA was NOT a useful predictor
accuracy of meniscal click or pop on PE and incidence of meniscal injury
pop/click only 63% accurateexacerbation of lameness was 52% SN to IS meniscal injury meniscal injury incidence ranges 33-77%
differentials for stifle pathology
- CrCL rupture2. MPL3. meniscal injury4. OC/OCD femoral condyle5. neoplasia6. traumatic fracture/avulsions7. collateral or LDE injury8. CdCL rupture9. puppy laxity–normal abrupt stop
arthroscopic findings of CrCL disease
- early partial tearing2. edematous homogenous ligament3. palpable laxity4. synovitis5. cartilage fibrillation6. meniscal pathology7. eburnation8. osteophytosis9. enthesiophytes
T/Fmeniscal mineralization may be an incidental finding
TRUEespecially in cats (incidence 46%) but they were older, weighed LESS, and had lower BCSFreire et al Vet Sx 2010
reported incidence of radial tears of the LATERAL meniscus
77%significance is unknown Ralphs et al JAVMA 2002
postliminary vs latent meniscal tears
postliminary–tears that occur AFTER initial surgical procedure that may be a result of continued or residual stifle joint instabilitylatent–present but not detected at the original surgeryincidence of post op meniscal injury varies 3-17%
accurate diagnosis of meniscal injury arthroscopy vs arthrotomy
arthroscopy + probe — 8x more likely to detectarthrotomy + probe —2.1 -2.6 xcompared to direct observation alone
classifications of meniscal tears (7)
- vertical longitudinal (nondisplaced)2. bucket handle (most common–type of displaced vertical longitudinal tear)3. flap tear (progression of bucket handle–detach)4. radial tears5. horizontal tear (can’t palpate, need MRI/US)6. complex tears7. degenerative tears (common)
types of meniscectomies
- total meniscectomy2. partial meniscectomy (removes just the axial damaged portion)3. hemimeniscectomy
list extracapusular techniques for CrCL injury
- Lateral fabellar suture (knots, crimps, suture variations)2. Modified Retinacular Imbrication Techinque3. Fibular head transposition (attachment LCL–less favored)4. TightRope (bone tunnels and polyblend suture)techniques rely on periarticular fibrosis for long term stability
list intraarticular techniques for CrCL injury
- Autografts (patellar ligament, ST, Gracillis, Quad muscles tendon, fascia lata)2. allografts (achille’s tendon, patellar lig, fascia lata)–no clinical reports3. xenografts (bovine)–unsuccessful4. Synthetic material (goretex, dacron, silk)designed to replace CrCL anatomicallybone-patellar ligament (graft)-bone preparation is the standard with “over-the top” position for the femoral graftmay require “notchplasty” to prevent impingement of the graftgraft length 1.5x patellar-tibial tuberosity distance
list osteotomy techniques for CrCL injury
- closing wedge osteotomy (remove TPA +5–shortens tibia)2. TPLO (goal 6.5 degrees (0-14)3. TTA4. CORA based leveling osteotomy5. Modified Maquet 6. triple tibial osteotomy
characteristics of nylon leader line
superior to other types of nylon (recover resting tension, high failure load, greater stiffness, and elongates less)biologically inert, low bacterial adherenceminimally affected by steam or ethylene oxide sterilizationcrimping is better than square knot
angular limb correction (tibial valgus, varus) and TPLO
sliding distal jig arm medially (away from tibia) —corrects varussliding distal jig arm laterally (toward tibia)–corrects valgus
T/Fthe source of hemorrhage during TPLO is typically from popliteal artery and vein
FALSE CRANIAL TIBIAL ARTERY OR VEINin the past errantly termed popliteal artery and vein
list methods of repair for MPL trochleoplasties
- trochlear wedge recession2. trochlear block recession3. Trochlear chondroplasty4. Abrasion sulcoplastydepth of groove should accommodate 50% of the depth of the patellacombined with TTT, Lateral imbrication, Medial release+/- antirotational suture +/- osteotomies to correct ALD
conformational abnormalities that may lead to development of MPL
- coxa vara (decreased angle of inclination of femoral neck)2. femoral varus3. proximal tibial varus with internal rotation4. shallow trochlear groove5. hypoplasia medial femoral condyle6. poorly developed of absent medial trochlear ridge
patella alta definition in large breed dogs
patellar ligament length (L) : patella length (P)L:P > 2 had patella altamay put at risk for MPL
normal aLDFA
~94-98 degreesmay determine whether or not femoral varus is present
classification of ligament injuries
- overstretch2. partial/mild tear3. complete tear or avulsion
ligamentous repair of the stifle
- prosthetic ligament repair of suture, spiked washer/screws, and figure eight2. primary repair of ligament (locking loop) +/- augmentation with suture, fascia3. avulsion of attachment repair with screw/washer or divergent pins**also bone tunnels and bone anchorsstifle at 140 degreeslook and tx concurrent injuries
treatment of patellar fracture
displaced or nondisplacedbasilar, apical, or bodyrepair: –conservative (if nondisplaed)–pin –pin, tension band –pin, 2 tension bands–pin, 2 tension bands, circumferential cerclage–circumferential cerclage around patella + tension band in quads
treatment patellar ligament rupture
mattress suture 16-20 gauge orthopedic wire or 80-100 lb monofilament nylon placed in quad or bone tunnel through patellar body and through hole in tibial tuberositylocking loop of remaining ligament with non absorbable (consider fascia augmentation)
stifle OC/OCD
4th most common location –check bilaterally(shoulder>elbow>tarsus>stifle)axial surface of lateral and/or medial femoral condyle(defect, free mineral body, sclerosis, effusion, 2nd DJD)remove, debride, forage, lavage, closeOATspx fair-poor
gastronemius muscle avulsion of origin
f(x) gastroc= stifle flexion, extension tarsusavulsion–plantigrade stancetx: sx reattachmentsuture to remaining soft tissue OR reattach with bone anchors, bone tunnels, screws/washers to caudal aspect of femur
