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