Fusion of Double-layered Patella Using a Single Small Fragment Partially Threaded Screw

Abstract

The double-layered patella (DLP) was first described by Büttner in 1925 and is now considered pathognomonic for multiple epiphyseal dysplasia. In this study, we describe the case of an 11-year-old girl with multiple epiphyseal dysplasia and right-sided DLP. The patient presented with intermittent unilateral anterior knee pain and swelling. There was a reproducible high-pitched click with every step. Imaging showed a DLP in good alignment. Surgical management comprised open debridement and fixation of the 2 patellar layers using one 3.5 mm (removed-) partially threaded AO small fragment screw. Standard radiographs of the right knee, 3 years postoperatively, showed sound union of the 2 patellae. The patient now plays sports, and recent examination showed a full range of movement with no instability, effusion, or tenderness. We conclude that surgical fusion of the patellar fragments in DLP using a single small fragment partially threaded screw provides excellent outcome at 3 years follow-up. This case report shows a comparatively simple and economical surgical solution to the problem of DLP.