a. Tangential view of the patella (Merchant view) may demonstrate lateral displacement or tilt of the patella. Narrowing of the joint space is suggestive of patellofemoral arthritis.
b. Lateral view of the knee may demonstrate a high-riding patella (patella alta), which has been associated with patellofemoral pain. Patella alta is defined as a ratio of the length of the patellar tendon to the length of the patella greater than 1.2:1.0.
4. Differential diagnosis. Chondromalacia patellae must be distinguished from meniscal tears. Meniscal tears are more frequently associated with a specific traumatic event and even more likely to result in a knee effusion, locking, and a reduction of range of knee motion. Meniscal tears may be ruled out by an arthrogram, MRI, or arthroscopic evaluation.
Was this article helpful?