title: Hidden lesions of the posterior horn of the medial meniscus: a systematic arthroscopic exploration of the concealed portion of the knee.
abstract: BACKGROUND
  Anterior cruciate ligament (ACL) tears are frequently associated with meniscal lesions. Despite improvements in meniscal repair techniques, failure rates remain significant, especially for the posterior horn of the medial meniscus.
  
  
  OBJECTIVE
  To determine whether a systematic arthroscopic exploration of the posterior horn of the medial meniscus with an additional posteromedial portal is useful to identify otherwise unrecognized lesions.
  
  
  METHODS
  Case series; Level of evidence, 4.
  
  
  METHODS
  In a consecutive series of 302 ACL reconstructions, a systematic arthroscopic exploration of the posterior horn of the medial meniscus was performed. The first stage of the exploration was achieved through anterior visualization via a standard anterolateral portal. In the second stage, the posterior horn of the medial meniscus was visualized posteriorly via the anterolateral portal with the scope positioned deep in the notch. In the third stage, the posterior horn was probed through an additional posteromedial portal. A χ2 test and logistic regression analysis were performed to determine if the time from injury to surgery was associated with the meniscal tear pattern.
  
  
  RESULTS
  A medial meniscal tear was diagnosed in 125 of the 302 patients (41.4%). Seventy-five lesions (60%) located in the meniscal body were diagnosed at the first stage of the arthroscopic exploration. Fifty lesions located in the ramp area were diagnosed: 29 (23.2%) at the second stage and 21 lesions (16.8%) at the third stage after minimal debridement of the superficial soft tissue layer. The latter type of lesion is called a "hidden lesion." Altogether, the prevalence of ramp lesions in this population was 40%. Meniscal body lesions (odds ratio, 2.6; 95% confidence interval, 1.18-5.18; P < .02) were found to be significantly correlated with a longer delay between injury and surgery.
  
  
  CONCLUSIONS
  Posterior visualization and posteromedial probing of the posterior horn of the medial meniscus can help in discovering a higher rate of lesions that could be easily missed through a standard anterior exploration. In numerous cases, these lesions were "hidden" under a membrane-like tissue and were discovered after minimal debridement through a posteromedial portal.
authors.affiliation: Bertrand Sonnery-Cottet, Centre Orthopédique Santy, 24 Avenue Paul Santy, 69008 Lyon, France. sonnerycottet@aol.com.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Sonnery-Cottet
authors.forename: Jacopo
authors.initials: J
authors.lastname: Conteduca
authors.forename: Mathieu
authors.initials: M
authors.lastname: Thaunat
authors.forename: François Xavier
authors.initials: FX
authors.lastname: Gunepin
authors.forename: Romain
authors.initials: R
authors.lastname: Seil
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D059549:Anterior Cruciate Ligament Reconstruction; D001182:Arthroscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D000070600:Tibial Meniscus Injuries; D016896:Treatment Outcome
keywords: anterior cruciate ligament; hidden lesion; meniscal lesion; meniscocapsular; meniscosynovial; ramp lesion