Introduction: Restoration of the normal mechanical axis of the knee joint and adequate ligament balancing are important for successful total knee arthroplasty (TKA). These goals are technically demanding and difficult to achieve in patients with severe varus deformity (hip-knee-ankle angle >20°) who have contracture of medial soft tissue, laxity of lateral soft tissue, and major bone defects. This video presents our novel technique to achieve efficacious and safe extension gap balancing with the use of trial components during TKA in patients with severe varus deformity and compares the results of these patients with those of a control group who underwent deep medial collateral ligament release only during primary TKA.

Methods: All patients underwent TKA at our institution between January 2012 and June 2015. Group one consisted of 40 patients (50 knees) with severe varus deformity and a hip-knee-ankle angle greater than 20° who underwent TKA with the use of trial components. Group two consisted of 48 one-to-one patient-matched controls (50 knees) who underwent TKA with deep medial collateral ligament release only. Propensity score matching was used. Matched variables included age, sex, body mass index, surgical side, diagnosis, and type of prosthesis. Mediolateral laxity of the knee joint was measured on valgus and varus stress radiographs. Clinical and radiographic assessments, including Knee Society scores, Western Ontario and McMaster Universities Osteoarthritis Index scores, and knee alignment, also were compared.

Results: Lateral laxity (lateral opening angle) was 3.6° ± 1.7° in group one and 3.2° ± 2.0° in group two 1 year postoperatively. Medial laxity (medial opening angle) was 2.3° ± 1.4° in group one and 2.7° ± 1.3° in group two 1 year postoperatively. No considerable difference in postoperative mediolateral laxity was observed between the two groups. Substantial differences were observed between the two groups with regard to preoperative knee alignment and clinical scores (Knee Society scores and Western Ontario and McMaster Universities Osteoarthritis Index scores); however, no differences in postoperative assessment were observed between the two groups.

Conclusion: Our novel technique to achieve extension gap balancing with the use of trial components during TKA in patients with severe varus deformity was effective, reproducible, and safe.