Lateral Ligament Release for Valgus Deformity in Primary Total Knee Arthroplasty

In the arthritic knee, pathologic changes occur in both the bony and the soft tissue structures. In addition to the progressive erosion of articular cartilage and bone, contraction of the soft tissues in the affected compartment also occurs. In severe cases, the soft tissue structures in the contralateral compartment may also become stretched or attenuated. In the valgus knee, the progressive changes begin with the loss of the lateral joint space and contraction of the lateral soft tissues, followed by eventual stretching of the medial soft tissue structures. The lateral structures that become contracted include the iliotibial band (ITB), the lateral collateral ligament (LCL), the arcuate ligament (posterolateral capsule), the popliteal tendon, and the lateral head of the gastrocnemius. Krackow et al. have classified valgus knees into three groups depending on the extent of the changes that have occurred. Type I is defined as valgus deformity secondary to bone loss in the lateral compartment with lateral soft tissue contraction but intact medial structures. Type II is defined by additional medial soft tissue attenuation; type III is defined as severe valgus deformity with valgus malpositioning of the proximal tibial joint line following overcorrected proximal tibial osteotomy. In total knee arthroplasty (TKA) surgery, the asymmetry in the medial and lateral soft tissue tension must be addressed. One of the central principles in TKA surgical technique is the creation of equal flexion and extension gaps with symmetric medial and lateral soft tissue tension (Fig. 1A, B). Failure to achieve these goals may result in postoperative instability. While the importance of creating balanced soft tissue tension is widely recognized, no consensus exists among orthopedic surgeons about how to accomplish this goal in knees with preoperative valgus deformities. Rather, numerous soft tissue-balancing techniques have been proposed that are based upon different philosophical concepts. These different techniques can be divided into three broad categories: (1) release of the contracted lateral soft tissue from the femur, the tibia, or both; (2) advancement of the lax medial structures either proximally or distally, with or without concomitant lateral releases; and (3) use of a lateral approach to the knee. An alternative technique that has been used in an elderly subgroup of patients with low physical demands involves the use of a constrained condylar prosthesis without any attempt to balance the soft tissue structures. Individual surgeons may employ one or more or the reported techniques based on their training and surgical philosophy. The techniques used by the authors and described in the subsequent sections are based upon the teachings of Insall. These techniques represent a distillation of lessons gained from 3 decades of experience in TKA surgery. During the 1970s and early 1980s, release of the contracted lateral structures was performed from the femur. First the iliotibial band was divided. Then the lateral capsule, together with the LCL and popliteus tendon, was cut from the femoral condyle. Occasionally, the posterior capsule and lateral head of the gastrocnemius muscle also required division at the level of the lateral femoral condyle. In addition, during that time, a formal exploration and release of the peroneal nerve was undertaken both at the level of the fibular neck and at the site where the nerve passes through a fibrous raphe into the anterior compartment. This mobilization was performed to mitigate the ischemic effects on the nerve by lengthening the lateral side. Exploration of the nerve was performed either through the usual anterior midline incision, Address correspondence and reprint requests to Henry D. Clarke, M.D., Insall Scott Kelly Institute for Orthopaedics and Sports Medicine, 170 East End Avenue, New York, NY 10128. E-mai l : HCLARKE@chpnet.org Techniques in Knee Surgery 2(2):74–81, 2003 © 2003 Lippincott Williams & Wilkins, Inc., Philadelphia