In general, patients do not have problems with medial patellar instability. However, in some patients who have had a lateral release, they will have symptoms of the patella subluxing medially. This can occur in patients with an extensive lateral release.
This can be one of the most difficult problems to diagnose in orthopaedics because it is not well described. I have seen many patients who have seen greater than five physicians who have undergone trials of taping, physical therapy, bracing and other treatment means without a true diagnosis of their condition. In addition, many of the patients feel as if there patellar subluxes laterally when it is actually subluxing medially. The way that we help the patient to discern this and to diagnosis the problem is to perform “reverse” McConnell taping. This taping technique is when the patellar is held laterally to attempt to prevent it from subluxing medially.
The medial patellar apprehension test is performed by placing the knee in full extension and applying a medial translation force to the patella. The knee is then flexed. If the patella does significantly sublux medially, the patient will note the feeling of apprehension and the patella can be found to reduce back into the bony confines of the trochlear groove with further knee flexion. In general, medial patellar instability occurs in the first 0°-30° of knee flexion.
As always with a knee exam, the contralateral patella should be assessed to determine the amount of normal medial patellar subluxation in a particular patient.