Double-layered patella management in total knee arthroplasty for secondary osteoarthritis: A case report.

Double-layered patella (DLP) is an osseous disorder associated with multiple epiphyseal dysplasia (MED). A thorough investigation should be conducted prior to surgery to assess the role of each layer and their vascularization in order to establish the best surgical strategy. We present the case of a woman in her late 50s with MED, bilateral DLP, and secondary osteoarthritis treated by a left total knee arthroplasty (TKA). To plan the surgical procedure, bilateral knee magnetic resonance imaging was obtained to study the anatomy of the two bony layers and their relationship to the extensor mechanism. In addition, a computed tomography angiography was performed to study the origins of arterial blood supply to the patella layers to avoid postoperative bone necrosis. During a standard TKA procedure, after adjusting the thickness of the posterior layer, we fused both layers using outside-in headless compressive screws. Clinical outcome was satisfactory with no anterior knee pain and radiographs showed signs of bone fusion between layers at last follow-up. No case report was found in the literature in which a full preoperative investigation was made to establish the best surgical management of a DLP during TKA. In such a case, the surgeon should be aware of the distinct roles of both layers (whether in the case of trauma or scheduled surgery) and make sure that the reconstruction plan will provide a favorable outcome.