Ligamentous balancing in primary total knee replacement

Ligament balancing in total knee replacement requires a careful analysis of all peri-articular structures providing knee stability and proper kinematic function. The sequence of balancing procedures begins with tibial and femoral resections to restore anatomic alignment of the extremity. Collateral and cruciate ligament balancing is then required to establish a rectangular extension gap. At the same time, flexion contracture or recurvatum deformity must be addressed. Simultaneous flexion gap changes can occur as a consequence ligamentous balancing of the knee in extension. A rectangular flexion space to match the extension gap should be established to provide normal kinematic function during flexion range. At the same time, femoral component rotation should be addressed to enhance patellofemoral alignment. Posterior cruciate ligament balancing, resection, or substitution needs to be considered, as this ligament directly affects gap kinematics. Mobile bearing articulations, of greater recent interest and supported by excellent long-term clinical results, require precise instrumentation and accurate gap balancing due to the additional risk of potential bearing instability inherent to the design.