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Proximal Realignment with Cartilage Restoration for Patellar Instability and Chondromalacia

This case appears in the HSS publication Grand Rounds from HSS - Management of Complex Cases, Winter 2014 - Volume 4, Issue 3, Case 2

Case 3, presented by Beth E. Shubin Stein, MD, Sabrina M. Strickland, MD and Jacqueline Munch, MD describes a 41-year-old female who suffered her first left knee patellofemoral dislocation when she was 13 years old. From that time until she presented to our center, she suffered at least 12 more dislocations. On physical examination, she had a neutral standing alignment, a 1+ left knee effusion, near full range of motion, and left knee crepitus. She had a significantly tight left knee lateral retinaculum, which did not allow eversion of her patella to neutral, and a positive J sign. She had no signs of generalized ligamentous laxity. She had markedly positive apprehension sign to lateral stress on the left patella that was not present on her right knee. Her motor and sensory exam was within normal limits. On x-rays and MRI, there was no evidence of patella alta as her Caton Deschamps ratio was 1.1. Her tibial tubercle-trochlear groove distance (TT-TG) was 15mm. The MRI demonstrated a 10.6mm x 9.8mm, full-thickness, central articular cartilage defect on the left patella in the setting of a severely hypoplastic sulcus (Figure 1). Given that the patient had neither patella alta nor a TT-TG over 20mm, and her cartilage lesion was in a central location and thus not ‘unloadable’, distal realignment was not indicated. However, the cartilage defect was concerning as a potentially persistent pain generator. Thus, she was a candidate for a medial patellofemoral ligament (MPFL) reconstruction using semitendinosus allograft and a cartilage restoration procedure. In order to minimize donor site morbidity and wait time for a potential osteochondral allograft donor, we proceeded with placement of juvenile articular cartilage allograft (1). Postoperatively, the patient demonstrated good patella stability to lateral translation with no further apprehension. She suffered initially with symptoms consistent with causalgia or complex regional pain syndrome, but was treated effectively with pregabalin and gentle physical therapy. Seven months postoperatively, her causalgia symptoms had resolved, and she reported a pain-free knee except for rare twinges of discomfort. MRI showed excellent fill of the cartilage defect after the allograft treatment, an intact MPFL and improved patellar alignment compared to her subluxed patella preoperatively (Figure 2).

Read full case details in Volume 4, Issue 3 of Grand Rounds - Complex Cases.

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