title: Fusion of double-layered patella using a single small fragment partially threaded screw: a case report.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  This case report shows a comparatively simple and economical surgical solution to the problem of DLP.
authors.affiliation: The General Infirmary at Leeds, Great George Street, Leeds, West Yorkshire. hannah_leng@homtail.com
authors.forename: Hannah Catherine
authors.initials: HC
authors.lastname: Leng
authors.forename: Patrick
authors.initials: P
authors.lastname: Foster
authors.forename: Peter Alexander
authors.initials: PA
authors.lastname: Templeton
mesh_terms: D001863:Bone Screws; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D019637:Orthopedic Procedures / Q000295:instrumentation / Q000379:methods*; D010009:Osteochondrodysplasias / Q000150:complications*; D010329:Patella / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D016059:Range of Motion, Articular; D016896:Treatment Outcome