Correction of malformative patellar instability in patients with nail-patella syndrome: a case report and review of the literature

Orthop Traumatol Surg Res. 2013 Oct;99(6):749-54. doi: 10.1016/j.otsr.2013.03.031. Epub 2013 Sep 9.


Nail-patella syndrome (NPS) or hereditary onycho-osteodysplasia is a relatively rare autosomal dominant disorder with the classic tetrad of fingernail abnormalities, hypoplastic patellae, radial head dislocation and iliac horns. The anatomic abnormalities in NPS often lead to subluxation or dislocation of the patellaeca causing knee instability and pain. Although most existing literature regarding the knee manifestation of this syndrome has focused on the clinically and radiological changes, only a few articles discussed the surgical treatment. This study reports the clinical, radiological and arthroscopical findings and a 24-month follow-up after operative stabilisation considering the underlying pathomorphology of malformative patellar instability in an 11-year-old girl. The findings of this study confirm the unique pathology of NPS with a synovial band preventing the engagement of the patella into the trochlear groove. NPS is a rare disorder and has to be considered in cases with untypical patella dislocation. The underlying pathology differs completely from patients with patellofemoral instability. The aim of orthopaedic surgery should be correction of the underlying pathology with resection of the synovial band and an additional realignment of the patella by recentering of the quadriceps muscle. Considering the underlying pathology good clinical results can be expected.

Keywords: Malformative patellar instability; Myotome; Nail-patella syndrome; Operative stabilization.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Arthroscopy / methods*
  • Child
  • Female
  • Follow-Up Studies
  • Humans
  • Joint Instability / diagnostic imaging
  • Joint Instability / etiology
  • Joint Instability / surgery*
  • Knee Joint / diagnostic imaging
  • Knee Joint / physiopathology
  • Minimally Invasive Surgical Procedures / methods
  • Nail-Patella Syndrome / complications
  • Nail-Patella Syndrome / diagnosis
  • Nail-Patella Syndrome / surgery*
  • Patellar Dislocation / diagnostic imaging
  • Patellar Dislocation / etiology
  • Patellar Dislocation / surgery*
  • Patient Positioning
  • Radiography
  • Rare Diseases
  • Recovery of Function
  • Risk Assessment
  • Time Factors
  • Treatment Outcome