Revision total knee arthroplasty: Management of ligamentous instability

Abstract

Instability after total knee arthroplasty is second only to infection as a cause for revision within the first 5 years. As the numbers of knee arthroplasties performed in the United States grow at a steady rate, this clinical problem will likely increase accordingly. In managing these patients, it is critical to identify a clear etiology before proceeding with revision surgery. A thorough history and careful physical exam are both crucial to proper management. Recurrent bloody effusions should elevate suspicion for ligamentous instability as well as lateral patella tilt often signifying femoral or tibial component malrotation. Preoperative planning is also essential to ensure that all necessary implants are available; however as a general rule, the least constraint possible to allow for a stable knee arthroplasty should be utilized. While the best solution to this problem is prevention, these cases of instability do provide insight into potentially avoidable mistakes at the time of primary surgery. There are however unavoidable circumstances that can lead to this problem, and it is important to be familiar with current techniques and available equipment necessary to manage such cases. The goal of revision knee surgery in any of these cases is to restore a mechanically stable, balanced, functional knee. If the specific etiology can be identified prior to surgery, operative efforts will likely be more successful with reproducible outcomes.