Ligament Injury Flashcards
What are the 3 articulations of the stifle joint?
- femorotibial - main, primary weight bearing
- femoropatellar - improves efficiency of extension by increasing the movement orm of the quadriceps
- tibiofibular - secondary support
What are the 4 sesamoid bones of the stifle?
- patella - blunt proximally, pointed distally (apex)
- lateral fabella - larger, spherical
- medial fabella - smaller, angular
- popliteal - in the popliteal tendon of the lateral condyle of the tibia
What is the purpose of sesamoid bones?
relieve tension within muscles and tendons, allowing for increased weight bearing and tolerance by redistributing forces throughout a muscle or tendon —> protection from strain and injury
Femorotibial joint:
Where do the cranial and caudal cruciate ligaments originate and insert?
CRANIAL = originates from the caudomedial aspect of the lateral femoral condyle, inserts on the medial tibial plateau
CAUDAL = originates from the craniomedial aspect of the medial femoral condyle, inserts on the posterior tibial plateau
Menisci:
medial most commonly tears
What is the function of the cranial cruciate ligament? In what 3 ways does it do that?
stability of the stifle joint
- limits cranial translation of the tibia
- limits internal rotation of the tibia
- limits hyperextension of the stifle
What are the stifle menisci made of? What is their purpose? What is their blood supply like?
C-shaped fibrocartilage primarily made up of Type 1 collagen in a matrix
resists hoop stress
poor —> thick periphery is vascularized by plexi in the joint capsule
What is the purpose of a meniscal release? How. isit performed?
treats impingement by allowing the caudal horn of the meniscus to move more freely with movement of the joint in the presence of cranial tibial thrust
mid-body meniscal transection +/- transection of the caudal tibial ligament
Are complete meniscectomies performed?
NO —> causes the development of advances arthritis because there is no longer any cushion
- it used to be thought that the menisci do not do much
What is the most common etiology of cranial cruciate ligament tears in dogs?
degenerative
(trauma in humans)
What are the 5 major causes of the degeneration that leads to cruciate ligament tears?
- conformational abnormalities - proximal tibia, straight legs
- hormonal - early castration
- autoimmune
- age
- body weight
(idiopathic possible)
How is cranial cruciate ligament tears diagnosed?
- ORTHOPEDIC EXAM - gait analysis, compensatory thickening, cranial drawer, tibial compression
- RADIOGRAPHS - can’t see ligaments, secondary changes
What cats are likely to tear their cranial cruciate ligaments?
old, obese
How is the gait changes by cranial cruciate tears? What is the sit test?
shifting, off-loading
it hurts to flex legs, so dogs with a torn CrCL will keep their legs extended
How is the cranial drawer test performed?
- place thumb and finger of one hand on the fabella of the femur (+ pointer finger on patella)
- place thumb and finger of other hand on the tibial crest and fibular head
- while holding the femur in place, apply a firm cranially directed force to the tibia
POSITIVE = tibial will be able to slide forward in flexion +/- extension
How is a tibial compression test performed?
- place index finger on patella, and other fingers on femoral condyles
- push the hock proximally to flex it
POSITIVE = gastrocnemius pulls femur caudally and tibia is able to move up
What can radiographs show in patients with CrCL tears?
- joint effusion - fat pad sign
- osteophytes
- medial buttress
- sunchondral sclerosis
What is the point of extracapsular techniques when repairing CrCL? How is this performed?
tightens joints by grabbing bone/ligaments and anchoring them to the tibial tuberosity
lateral retinacular stabilization
- synthetic monofilament around fabella/bone anchor
- tunnel in tibial proximal muscle
- recommended in cats/small dogs
What is the point of Tightrope CrCL repair?
extracapsular - drills into bone and replicates ligament
What is the point of fibula head transposition for CrCL repair?
extracapsular - pull fibula forward so that the LCL can replicate the CrCL
- recommended for large dogs, durable
What is the most common intracapsular technique used to repair CrCL tears?
over the top - strip of fascia lata is cut and passed through a tunnel where the cruciate was, then through the condyles, and attached through the lateral surface of the condyle
What is the purpose of performing a TPLO?
adjusts the slope of the tibia so that the femur slides cranially instead of caudally
What is the purpose of performing a TTA? How does it compare to a TPLO?
cut the tibial crest and place a plate and spacer to advance it - makes crest perpendicular to the patellar tendon and prevent the tibia from moving forwards
not performed as commonly —> parts are flimsy and avulsions are common
