Primary Total Knee Arthroplasty in Patients with Severe Varus Deformity. A Comparative Study

Varus deformity is a common finding in candidates for total knee arthroplasty (TKA), but very little has been written concerning the problems encountered in correcting these deformities at the time of arthroplasty. Compared to patients without deformities, this group of patients require more attention to the technical aspects of the arthroplasty, especially bony alignment and ligament balancing. Specific operative techniques used to correct severe varus deformities at primary TKA were evaluated, and the clinical and roentgenographic results were compared with those of a control group of patients without preoperative angular deformity. Operative findings and clinical results in 27 knees (20 patients) with a minimum preoperative varus deformity of 20 degrees (average follow-up period, 58.7 months; range, 24-102 months) were compared with those of 40 knees (31 patients) with a preoperative angulatory deformity of less than 5 degrees varus or valgus (average follow-up period, 50.0 months; range, 24-90 months), in whom a minimally constrained, posterior-cruciate-ligament-sparing prosthesis was implanted. Operative time was an average of 30 minutes longer in the varus deformity group. The average knee evaluation score in the varus group was 89 points, and for the nondeformity group it was 92 points (p less than 0.02). There were no fair or poor results in the varus deformity group; there was one poor result in the nondeformity group. Postoperative knee are of motion was 98 degrees in the varus deformity group and 107 degrees in the nondeformity group. After arthroplasty, the average angle between the mechanical axis of the femur and the tibia was 3 degrees varus in the varus deformity group and 0 degree varus in the nondeformity group (p less than 0.006). Postoperative functional scores of patients in the varus deformity group approached, but were not equal to, the nondeformity group. Greater variability in results and longer operative times were needed in the varus deformity group. Postoperative alignment of the varus deformity group tended to be in residual varus.