Upper Fixation of Patella involves which anatomical interaction?

Upper Fixation of Patella involves which anatomical interaction?

• A. Locking of the patellar ligament over the medial femoral trochlear ridge
• B. Dislocation of the patella
• C. Fracture of the patella
• D. Tearing of the cruciate ligaments

Answer: (B)

Upward fixation of the patella occurs when the patella locks over the medial femoral trochlear ridge, typically because the medial patellar ligament and surrounding retinacular tissue engage the ridge and hold the knee in extension. This locking keeps the stifle from bending until external manipulation or muscle action frees the patella to move back into place. It is a locking interaction, not a dislocation. A dislocation would mean the patella has moved out of its normal groove; a fracture would involve a broken bone, and tearing of the cruciate ligaments involves the knee ligaments rather than the patellar engagement that causes the fixation.

Upward fixation of the patella occurs when the patella locks over the medial femoral trochlear ridge, typically because the medial patellar ligament and surrounding retinacular tissue engage the ridge and hold the knee in extension. This locking keeps the stifle from bending until external manipulation or muscle action frees the patella to move back into place. It is a locking interaction, not a dislocation. A dislocation would mean the patella has moved out of its normal groove; a fracture would involve a broken bone, and tearing of the cruciate ligaments involves the knee ligaments rather than the patellar engagement that causes the fixation.