Balancing the Gaps

Algorithm

Introduction

TKA poses significant challenges to achieving fixation, stability, alignment, and joint line restoration. Meticulous surgical technique with the appropriate implants is needed for satisfactory surgical outcome. With improvements in instrumentation and prosthetic design, the goals of revision TKA can be achieved with the use of modular augments, metaphyseal cones, and stems. However, obtaining flexion and extension gap balance remains the cornerstone of a successful arthroplasty.

Numerous causes of early TKA failure have been identified. Instability is a common mode of failure that can be largely attributed to poor management of the flexion/extension gaps. The reported incidence of postoperative instability leading to revision TKA ranges from 13% to 33%. Implant malpositioning and malrotation of the components further complicate revision TKA stability. Regardless of the cause, flexion/extension gap balancing determines the success and longevity of revision surgery. Failure to obtain balanced flexion and extension gaps may lead to catastrophic complications, including recurrent instability and, in the worst case, knee dislocation.