VETERINARY
The stifle is the largest joint in the horse and is the articulation between the tibia, femur, and patella (knee cap). The equine stifle is host to a wide range of conditions causing lameness. A combination of clinical examination, lameness evaluation, diagnostic local analgesia, radiography, and ultrasonography is required as a minimum in the detection of stifle pathology. Additional diagnostic aids such as arthroscopy and computed tomography/ MRI may be employed if further information is required. In all cases a thorough understanding of the complex anatomy of the stifle is essential. WORDS: THOMAS O’KEEFFE PHOTOS: FiOnA BOyD, CAROlinE nORRiS, THOMAS O’KEEFFE
Anatomy of the Stifle
The condyles of the femur do not conform in shape to the tibial plateau, as two crescentshaped menisci made of fibrocartilage provide congruency between the two bones and function to cushion the articular cartilage from the compression forces of weight bearing. The center of the tibial plateau forms the intercondylar eminence comprising two 34
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prominences (medial and lateral intercondylar tubercles). The cranial ligaments of each meniscus are anchored to the top of the tibia at the medial and lateral intercondylar eminences respectively with the menisci also attached to the joint capsule. The patella is a large bone in the insertional tendon of the quadriceps femoris muscle. From its base, three patellar ligaments converge distally to
attachments on the tibial crest. The stifle has three synovial spaces: the femoropatellar joint and the medial and lateral femorotibial joints. The femoropatellar joint at the front of the stifle is the articulation of the patella and the two trochlear ridges. The femorotibial joint spaces are distinct from each other and are found between each meniscus and its corresponding femoral condyle. The two cruciate ligaments lie outside the joint cavity between the medial and lateral femorotibial joint compartments.
Examination of the Stifle
Palpation of the stifle is undertaken with the limb weight bearing. Apparent effusion of any joint compartment should be judged against the opposite limb and attention paid to stance, as limb position can affect perception of intra-articular pressure. The femoropatellar joint is the only compartment where distension may be noted visually. Medial femorotibial joint distension is readily palpable on the inside of