title: Osteonecrosis of the Knee After Anterior Cruciate Ligament Reconstruction: A Report of 5 Cases.
abstract: BACKGROUND
  Anterior cruciate ligament (ACL) reconstruction is performed commonly, with a low risk of complication. Osteonecrosis of the knee is a potentially devastating condition and has been observed both spontaneously and after meniscectomy, although osteonecrosis has not been described as a complication after ACL reconstruction.
  
  
  OBJECTIVE
  To describe the development of osteonecrosis of the knee in 5 patients after arthroscopic ACL reconstruction.
  
  
  METHODS
  Case series; Level of evidence, 4.
  
  
  METHODS
  This study involved 5 patients (mean age, 33.2 years) who developed osteonecrosis of the knee after ACL reconstruction. A retrospective chart review was performed to identify clinical characteristics and surgical factors present in each of the 5 cases.
  
  
  RESULTS
  In 4 cases, the pathologic changes were present in both the medial and lateral femoral condyles, with isolated lateral condyle changes in the other case. The mean time to diagnosis was 11.6 months. These patients underwent an average of 1.8 additional surgical procedures after the diagnosis of osteonecrosis.
  
  
  CONCLUSIONS
  Osteonecrosis of the knee is a rare outcome after ACL reconstruction. We are unable to identify clear risk factors for the development of this complication, although we hope the presentation of these cases will help promote the identification of other cases in future studies.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Drew A
authors.initials: DA
authors.lastname: Lansdown
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Shaw
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Christina R
authors.initials: CR
authors.lastname: Allen
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, California, USA.
authors.forename: C Benjamin
authors.initials: CB
authors.lastname: Ma
keywords: anterior cruciate ligament reconstruction; knee arthroscopy; osteonecrosis of the knee; postoperative complications