title: Arthroscopic and magnetic resonance imaging evaluation of meniscus lesions in the chronic anterior cruciate ligament-deficient knee.
abstract: OBJECTIVE
  We performed this prospective study to evaluate the incidence of meniscus tears arthroscopically and the effectiveness of magnetic resonance imaging (MRI) in detecting these lesions in patients with chronic anterior cruciate ligament (ACL)-deficient knees.
  
  
  METHODS
  We reviewed 50 patients (46 male and 4 female) with a mean age of 27 years (range, 18 to 48 years) who underwent ACL reconstruction for chronic ACL tears. Injuries were classified as chronic because arthroscopy was performed after more than 6 weeks of injury. All 50 patients had clinical and MRI evaluation followed by knee arthroscopy. The MRI and arthroscopic findings were then analyzed by a single independent reviewer. The presence of meniscus tears and their morphologic types and locations were analyzed. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI were calculated.
  
  
  RESULTS
  On arthroscopy, a medial meniscus tear was found in 18 patients (36%), a lateral meniscus tear was found in 11 patients (22%), both menisci were torn in 8 patients (16%), and no meniscus lesion was found in 13 patients (26%). The most common morphologic type of tear seen in the medial meniscus was "complex" (n = 11 [42%]), and that in the lateral meniscus was "longitudinal" (n = 10 [53%]). The posterior horn of the meniscus was the most common tear site. The overall sensitivity, specificity, positive predictive value, and negative predictive value for detecting meniscus tears in chronic ACL-deficient knees on MRI were 90%, 89%, 87%, 93%, respectively.
  
  
  CONCLUSIONS
  We conclude from our study that in chronic ACL-deficient patients, the prevalence of posterior horn medial meniscus tears seems to be high. Anterior horn tears and radial and horizontal patterns of meniscus tears seem to be rare in chronic ACL deficiency. MRI correlates well with arthroscopy and has high negative predictive values.
  
  
  METHODS
  Level I, prognostic prospective study.
authors.affiliation: Department of Orthopaedics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Sameer
authors.initials: S
authors.lastname: Naranje
authors.forename: Ravi
authors.initials: R
authors.lastname: Mittal
authors.forename: Hiralal
authors.initials: H
authors.lastname: Nag
authors.forename: Raju
authors.initials: R
authors.lastname: Sharma