Primary total knee arthroplasty in patients with fixed valgus deformity

Abstract

Ninety-nine knees in 81 patients evaluated from two to ten years and having enough valgus deformity to require specific soft-tissue release were studied. They were also compared to a control group of 40 knees in 31 patients with no angular deformity greater than 5 degrees, who were matched for age and diagnosis. All procedures were performed using a minimally constrained, posterior-cruciate-ligament-sparing prosthesis. Pre- and postoperative axial alignment was measured on weight-bearing long-standing roentgenographs. Analysis included examination for lucent lines in postoperative fluoroscopically positioned roentgenographs and clinical data summarized using the 100-point scoring systems developed by The Knee Society. Knees were classified as having Type I, II, or III valgus deformities: Type I was defined as valgus deformity secondary to bone loss in the lateral compartment and soft-tissue contracture with medial soft tissues intact; Type II was defined as obvious attenuation of the medial capsular ligament complex; and Type III was defined as severe valgus deformity with valgus malpositioning of the proximal tibial joint line after overcorrected proximal tibial osteotomy. Only cases of Type I and Type II were represented in the 99 knees reported. Type I patients were treated with lateral soft-tissue release, and Type II patients were treated with medial capsular ligament tightening (i.e., ligament reconstruction procedures on the medial side). The Knee Society postoperative knee score was 87.6 (+/- 10.6) and mean postoperative functional score was 52.3. Alignment was well corrected and knee scores for the Type I and II groups were almost identical as were the functional scores. The results were grouped as 72% excellent, 18% good, 7% fair, and 2% poor. Notably, the control group was 39 of 40 patients excellent, and only one poor. Ligament stability was satisfactorily established by lateral release in Type I and with the combined medial plication in the Type II patients. The ligament-tightening procedures were on the average 40 minutes longer than those for the Type I or the control groups. The controversial nature of the simultaneous ligament reconstruction method is recognized, but good experience is reported.