Medial collateral ligament laxity in revision ACL reconstruction

The medial collateral ligament (MCL) is the primary restraint to valgus stability of the knee. Familiarity with the anatomy of this ligament alongside with recognizing and addressing dysfunction of this structure in the setting of ACL reconstruction is of major importance, and failure to do so can result in excessive valgus stress applied to the ACL graft, leading to graft failure. Assessment of MCL function should begin with history, a thorough physical examination including alignment and gait, and then a detailed evaluation of all knee ligaments. Stress radiographs can be performed in selected cases to further assess medial gapping. Evaluation under anesthesia is then undertaken when surgery is indicated, followed by arthroscopic evaluation to assess the amount of medial compartment gapping. Surgical techniques to address medial side dysfunction in scenarios of ACL reconstruction surgery include medial side plication when the amount of medial compartment opening is less than 10 mm, but reconstruction is advisable when medial side opening is measured 10 mm or more. Multiple techniques for reconstructing the medial stabilizing complex have been described, including autograft as well as allograft type of tissue. Cases that involve valgus malalignment with the appearance of valgus-thrust gait should not be overlooked, since correcting the alignment with an osteotomy should be considered as the first surgical step.