Unlocking the 'pivot shift' in ACL surgery: medial meniscus evaluation and treatment.

摘要

Meniscal injury commonly occurs in conjunction with anterior cruciate ligament (ACL) disruption. Failure to recognize and treat these injuries may lead to less than ideal outcomes in ACL reconstruction. With their unique anatomical location, often at the peripheral rim of the posterior horn of the medial meniscus, the instability pattern of ACL deficiency may contribute to failure of injury recognition. Standard anterior viewing portals do not allow adequate visualization of a large portion of the posterior horn of the medial meniscus. Alternative viewing techniques, such as an accessory posteromedial arthroscopy portal or the Gillquist maneuver, may improve visualization of the posteromedial compartment, but require additional surgery and/or equipment. The pattern of instability inherent to ACL deficiency, or the "pivot shift," occurs when the surgeon attempts to visualize the posteromedial compartment with full extension of the knee and a valgus load. The knee "pivots" as the lateral tibial plateau anteriorly subluxes and rotates around the tibial spines. This rotation and subluxation closes down the posteromedial compartment and blocks visualization. A simple maneuver helps to eliminate this pathologic motion, or "unlock the pivot." During attempted visualization of the medial meniscus, the leg is held in mild flexion (207) with a valgus moment on the knee. While this position is held, the surgical assistant externally rotates the lower leg about the knee axis as the knee is extended and valgus is applied. This maneuver increases the surgeon's viewing area of the posteromedial compartment, which may decrease the need for accessory portals and additional equipment in the ACL deficient knee.