title: Diagnosis of ligamentous and meniscal pathologies in patients with anterior cruciate ligament injury: comparison of magnetic resonance imaging and arthroscopic findings.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) is routinely used to diagnose or support clinical diagnoses for meniscal or ligamentous injuries prior to offering patients arthroscopic treatment. However, the sensitivity of MRI for the detection of meniscal injury is not yet 100%. Sportsmen have occasionally returned to play with undiagnosed meniscal lesions on the basis of a normal MRI examination. This study was designed to assess the diagnostic parameters of MRI in patients with acute anterior cruciate ligament (ACL) injury.
  
  
  METHODS
  MRI and arthroscopic findings of 320 patients with acute ACL injury were included in this retrospective review. Patients belonged to a single surgeon from a high volume tertiary healthcare institution. All patients had either a MRI or an arthroscopic diagnosis of an acute ACL injury of one knee or both. All patients underwent therapeutic arthroscopy by the senior author routinely as part of arthroscopy-aided ACL reconstruction. Arthroscopic findings were the diagnostic reference based on which the positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and concordance strength of association of MRI were calculated for ACL, posterior cruciate ligament (PCL), medial meniscus (MM) and lateral meniscus (LM) injuries.
  
  
  RESULTS
  MRI was most accurate in diagnosing cruciate ligament injuries with a PPV approaching 100%. The PPV of MRI in diagnosing meniscal injuries was approximately 60%. MRI was almost 100% sensitive and specific in diagnosing ACL injuries and 82% sensitive and 100% specific in diagnosing PCL injuries. Conversely, MRI was 77% sensitive and 90% specific in diagnosing MM injuries; and 57% sensitive and 95% specific in diagnosing LM injuries.
  
  
  CONCLUSIONS
  MRI remains the gold standard for diagnosing soft tissue injuries of the knee. However, there is a false positive rate ranging from 6% to 11% for meniscal tears.
authors.affiliation: 1 Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore 169608; 2 Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore 119228.
authors.forename: Hamid Rahmatullah
authors.initials: HR
authors.lastname: Bin Abd Razak
authors.affiliation: 1 Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore 169608; 2 Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore 119228.
authors.forename: Andrew Arjun
authors.initials: AA
authors.lastname: Sayampanathan
authors.affiliation: 1 Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore 169608; 2 Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore 119228.
authors.forename: Thean-Howe Bryan
authors.initials: TH
authors.lastname: Koh
authors.affiliation: 1 Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore 169608; 2 Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore 119228.
authors.forename: Hwee-Chye Andrew
authors.initials: HC
authors.lastname: Tan
keywords: Arthroscopy; diagnostic parameters; knee; magnetic resonance imaging (MRI); radiologic