title: Biomechanical consequences of a complete radial tear adjacent to the medial meniscus posterior root attachment site: in situ pull-out repair restores derangement of joint mechanics.
abstract: BACKGROUND
  Complete radial tears near the medial meniscus posterior root attachment site disrupt the circumferential integrity of the meniscus (similar to a posterior root avulsion). These tears can compromise the circumferential integrity, and they have been reported in biomechanical studies to be comparable with the meniscectomized state.
  
  
  OBJECTIVE
  To quantify the tibiofemoral contact pressure and contact area changes that occur in cadaveric knees from complete posterior horn radial tears and subsequent repairs of the medial meniscus adjacent to the posterior root attachment site.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Six nonpaired fresh-frozen human cadaveric knees each underwent 45 different testing conditions: 9 medial meniscus conditions (intact, root avulsion, root repair, serial radial tear at 3, 6, and 9 mm from the root attachment site, and in situ repair at the same 3 distances from the root attachment site) at 5 flexion angles (0°, 30°, 45°, 60°, and 90°), under a 1000-N axial load. Tekscan sensors were used to measure contact area and pressure in the medial and lateral compartments.
  
  
  RESULTS
  The medial meniscus root avulsion and all radial tear conditions resulted in significantly decreased contact area and increased mean contact pressure compared with the intact state for knee flexion angles beyond 0° (P < .05). The root repair and in situ repairs restored contact area and pressure to levels statistically indistinguishable from those of the intact meniscus and increased contact area and decreased contact pressure compared with the corresponding tear conditions.
  
  
  CONCLUSIONS
  Posterior horn radial tears adjacent to the medial meniscus root that extend to the meniscocapsular junction can lead to derangement of the loading profiles of the medial compartment that are similar to a root avulsion. Repair of these radial tears with an in situ pull-out technique restored joint mechanics to the intact state.
  
  
  CONCLUSIONS
  Complete radial tears of the posterior horn of the medial meniscus, which occur relatively frequently, are biomechanically equivalent to root avulsions and could potentially lead to medial compartment arthrosis. An in situ repair offers an alternative treatment to meniscectomy and can reestablish the posterior anchor point, thus improving load distribution in the medial compartment. Future clinical studies of these repairs are recommended.
authors.affiliation: Robert F. LaPrade, The Steadman Clinic, 181 W. Meadow Drive, Suite 400, Vail, Colorado 81657. rlaprade@thesteadmanclinic.com.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Padalecki
authors.forename: Kyle S
authors.initials: KS
authors.lastname: Jansson
authors.forename: Sean D
authors.initials: SD
authors.lastname: Smith
authors.forename: Grant J
authors.initials: GJ
authors.lastname: Dornan
authors.forename: Casey M
authors.initials: CM
authors.lastname: Pierce
authors.forename: Coen A
authors.initials: CA
authors.lastname: Wijdicks
authors.forename: Robert F
authors.initials: RF
authors.lastname: Laprade
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D002102:Cadaver; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007718:Knee Injuries / Q000503:physiopathology / Q000601:surgery*; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery*; D008592:Menisci, Tibial / Q000503:physiopathology / Q000601:surgery*; D008875:Middle Aged; D011312:Pressure; D016059:Range of Motion, Articular / Q000502:physiology; D013536:Suture Techniques; D000070600:Tibial Meniscus Injuries; D016474:Weight-Bearing / Q000502:physiology
keywords: Tekscan pressure sensors; in situ repair; medial compartment load; medial meniscus; radial root tear