Stifle and Femur Flashcards
Landmarks of femur
- Lateral trochlear ridge
- Medial trochlear ridge
- Medial femoral condyle
- Lateral femoral condyle
- Intercondylar fossa
- Extensor fossa-cranial lateral
- Caudal lateral fossa
Patella
Parapatellar fibrocartilage-medial
Tibia
- Medial tibial plateau (condyle)
- Lateral tibial plateau (condyle)
- Intercondylar eminence of tibia
- Medial intercndylar eminence of the tibia - Tibial tuberosity
Joints
- femoropatellar
- suprapatellar pouch - Medial femorotibial
- cranial compartment
- caudal compartment - Lateral femorotibial
- cranial compartment
- caudal compartment
- -proximal
- -distal
Soft tissues (cranial)
- Patellar ligaments
- lateral
- middle
- medial - Parapatellar fat pad
- Quadriceps femoris muscles
- Sartorius
Soft tissues (caudal)
- Popliteus muscle
- Semimembranosus
- Semitendiosus
Soft tissues (medial)
- Medial collateral ligament
- Medial femoropatellar ligament
- Sartorious
- Gracillus
Soft tissues (lateral)
- Lateral collateral ligament
- Lateral femoropatellar ligament
- Insertion of the long digital extensor and peroneus tertius
- Biceps femoris
Intra articular soft tissues
- Medial and lateral meniscus
- Cranial cruciate ligament
- Caudal cruciate ligament
- Medial and lateral cranial meniscotibial ligaments
- Medial and lateral caudal meniscotibial ligaments
- Meniscofemoral ligament (lateral)
Common OA sites
- Medial femorotibial joint
- Lateral femorotibial joint
- Femoropatellar joint
Common fx or fragment sites
- Patella
- Trochlear ridge
- Medial intercondylar eminence of the tibia
- Avulsion of insertion of LDE (or PT)
- Avulsion insertion of Cr cruciate
Common site luxation
- upward fixation of patella (not true luxation)
2. Lateral luxation of patella (rare)
Common soft tissue injuries
- Collateral ligament desmitis, tear/disruption (M > L)
- Patellar ligament desmitis/tear/disruption
- Cruciate ligament tear or disruption (Cr > Ca)
- Meniscal tears
Common OC/OCD sites
- LTR-most common
- Medial trochlear ridge
- Patella
- Osteonecrosis of femoral condyles in foals
Subchondral bone cysts
- Medial femoral condyle
- Proximal tibia
- Meniscal cysts
Stifle/hock lameness
- Often bilateral
- difficulting changing gait
- bunny hopping
- squared off toes from dragging foot
Most useful radiographic view for femorotibial OA
caudocrania projection
earliest radiographic sign of medial femorotibial OA
lipping of medial tibial plateau due to osteophyte formation
Other radiographic signs of medial femorotibial OA
- Osteophyte formation on femoral condyle
- flattening of condyle
- areas of sclerosis and/or lysis in subchondral bone of weight bearing regions
Joint space narrowing is a sign of
end stage joint disease
-also depends on very careful positioning to determine
Best radiographic view for femoropatellar OA
lateral view
Earliest/most obvious sign of femoropatellar OA
osteophyte formation of distal patella
Etiology patellar fractures
Direct trauma
CS patellar fx
- variable effusion, swelling, lameness
2. May hold limb partially flexed, capable of weight bearing
Radiographic view if patellar fx
Standard 3 views + flexed lateral and patellar skyline
Patellar fx tx conservative
stall rest 2-3 mos
-patellar base fx doesn’t require sx
Patellar fx removal
- Arthroscopy preferred (can also visualize trochlear ridges)
- Can remove up to 1/3 of patella if medial saggital slab fracture
Patellar fx fixation
Can use lag screws or small plates
Crit fixation
1. complete disruption quadriceps apparatus
2. fx gap > 5mm
3. Malalignment articular surface
4. Unstable fragments palpable through skin
Patellar fx prog
Frag rem saggital fx-80-100% full athletic fxn
Disruption quad app-guarded for athlete
Trochlear ridge fractures
- Direct trauma
- mod-severe lameness, effusion, swelling
- crepitus/external wounds possible
- possiblity for joint sepsis
- tx arthroscopic rem frags
- prog good, non-weight bearing
Fx of medial intercondylar eminence of tibia
- not usually avulsion fractures
- best radiographic views for dx are caudocranial and flexed lateromedial
- removal salal frags
- prognosis good, more dependent on soft tissue injuries
Avulsion fx of long digital extensor tendon or peroneus tertius
- share common origin in extensor sulcus, lateral to distal aspect of lateral trochlear ridge of femur
- most common foals and young horses
- typically after forced hyperextension of the hindlimb
- dx rads, tx rem frags and rest
- prog-poor
Avulsion fx cranial cruciate ligament
rare
Lateral patellar lux
rare
soft tissue injury
dx: MRI, likely underdiagnosed
Collateral ligament injury
- u/s common method diagnosis
- complete disruptions or concurrent meniscal/cranial cruciate injury has poor prog
Patellar ligament injury
- jumpers are overrepresented
- partial or no response to block
- u/s diagnostic method of choice
- not sure of prognosis
Cruciate ligament injury
uncommon
prognosis poor if joint instability
Meniscal injury
Most common soft tissue injury of the stifle (medial meniscus)
-insidious onset
CS meniscal injury grades
G1: longitudinal tear cranial horn and meniscotibial ligament with minimal separation
-63% return to work
G2: Same as grade 1 with greater tissue separation
-56% return to work
G3: Tears extend beneath femoral condyle and cannot be viewed in their entirety
-5% return to work
Meniscal injury tx
Arthroscopic debridement (partial menisectomy) Prolonged rest (6 months)
Factors that decrease prognosis for meniscal injury
- Articular cartilage damage
- Concurrent soft tissue injuries
- Concurrent subchondral bone cyst
- Dystrophic mineralization of meniscus
Osteonecrosis of medial femoral condyle
rare
only in foals
Subchondral bone cysts
Common lesion of stifle, second to
-OC/OCD
Etiology of subchondral bone cysts
age 1-3 MFC most common site Other sites -proximal tibia -LCF -patella
suchondral bone cysts CS
Asymptomatic-prepurchase rads
May be unilateral or bilateral
variable response to hind limb flexion
variable response to diagnostic anesthesia
Subchondral bone cysts rads
- Caudocranial and flexed lateral most useful
- also take caudolateral-craniomedial oblique - ALWAYS take contralateral if lesion id’d
Femur fx rads
- Under general anesthesia
- Mediolateral and craniocaudal views
Femur fx U/S
- First line dx method adults
- Can be done standing
- Cannot assess configuration
