A lateral knee approach was used to perform knee arthroplasty in a patient with moderate to severe fixed knee valgus. A median lateral skin incision was made, the iliotibial bundle was extended in an apple pie-like fashion, and the joint capsule was incised from the lateral patella in a “Z” shape. Soft tissue balancing was performed by releasing the iliotibial bundle stop, lateral femoral and lateral tibial collateral ligaments and posterior lateral joint capsule. The distal femoral internal and external rotation osteotomy was defined as 5° external rotation, and the distal femoral rotation osteotomy was positioned using the Whiteside line combined with the axis of the internal and external epicondyles. The joint capsule was sutured in the flexed position, and the lateral cuff structure (deep) of the joint capsule was sutured to the edge of the medial support band (superficial).
From May 2004 to September 2006, eight cases of 10 patients with knee valgus osteoarthritis underwent total knee arthroplasty using a lateral approach. One male case with 1 knee and 7 female cases with 9 knees were performed. The mean age was 68.2 years (58-79 years). krackow [5] type I ectropion in 7 cases with 9 knees and type II in 1 case with 1 knee. All clinical fractions were greater than 15° and were severe exostoses. Both knees were replaced at the same time in 2 cases and 4 knees, while the single knee was replaced in 6 cases and 6 knees. 7 cases and 9 knees were treated with domestic posterior stabilized cemented prosthesis (TC-Dynamic, PLUS), and 1 knee was treated with imported rotating hinge prosthesis (RT-PLUSTM Solution, PLUS). The postoperative valgus deformity was completely corrected in all patients, and they were able to walk independently or with the aid of a walking frame for a distance of more than 100 m. The joint mobility improved from an average of 95.6° (85°-110°) before surgery to an average of 117.1° (100°-125°) after surgery. Passive internal and external rotation mobility improved from a preoperative average of 12.6° (9° to 15°) to a postoperative average of 0°. The mean FTA angle improved from 27.6° (20° to 40°) preoperatively to 6.8° (5° to 9°) postoperatively. the KSS score and functional score improved from 22.7 (9 to 48) and 26.5 (12 to 55) preoperatively to 86.4 (85 to 95) and 89.1 (80 to 95) postoperatively, respectively. The mean follow-up time after surgery was 19.6 months (1 month to 51 months), and there was no significant change in the femoro-tibial angle and good joint stability during the follow-up period.
Femoral epicondyle dysplasia, iliotibial bundle, lateral collateral ligament and posterior lateral joint capsule contracture are the main causes of knee valgus and the difficulties of soft tissue balancing and osteotomy in arthroplasty. The lateral approach with a “Z” shaped incision of the joint capsule can directly release the lateral ligaments and soft tissue structures, and effectively relieve the pressure on the common peroneal nerve and solve the problem of lateral soft tissue coverage. This approach is a more effective technique for joint replacement in patients with fixed moderate to severe knee valgus.