Recurrent locked knee caused by an impaction fracture following inferior patellar dislocation: a case report

INTRODUCTION: Locked knee caused by inferior patellar dislocation is considered rare in elderly patients. It was originally thought that, in the osteoarthritic knee, osteophytes on the pole of the patella become entrapped in the inter-condylar notch, which is managed by performing closed reduction and immobilization in a knee splint for three to four weeks. We present an unusual case of a locked knee with an impaction fracture. To the best of our knowledge, there have been no previous reports of such impaction fractures managed with arthroscopy. CASE PRESENTATION: We present an unusual case of an 88-year-old Caucasian woman with moderate arthritis who had a locked knee caused by an impaction fracture of the patella into the lateral femoral condyle. In this case report, we describe the need for arthroscopic surgery to prevent relocking of the knee in these patients. CONCLUSIONS: This case report emphasizes the need for careful assessment of locked knees in elderly patients. Impaction fractures should be considered in all rare cases of patellar dislocation, and we advocate arthroscopic assessment of the articular cartilage in these patients. This is an important consideration, as the population demographics change and such impaction fractures may become more common in patients with degeneration in the knees.