THREE TO SIX-YEAR FOLLOW-UP RESULTS AFTER HIGH FLEXION TOTAL KNEE ARTHROPLASTY – CAN WE ALLOW PASSIVE DEEP KNEE BENDING?

Abstract

We evaluated the minimum 3 year follow-up clinical and radiological results after Nexgen^® LPS-flex total knee arthroplasty (TKA).

Two hundred eighteen knees in 166 patients, who could be followed up more than 3 years after Nexgen^® LPS-flex TKA from October 2001 to February 2005, were evaluated retrospectively. The average age was 64.2 years. Twenty-two patients were male and 144 patients were female. The mean follow-up period was 51 months (range 36–73 months). The evaluations included the preoperative and postoperative range of motion (ROM), Knee Society (KS) Score, tibiofemoral angle and postoperative complications.

The ROM increased from preoperative mean flexion contracture of 8.7° and further flexion of 117.3° to postoperative mean flexion contracture of 1.8° and further flexion of 131.3°. The KS knee score and function score improved from 52 and 38 before surgery to 87 and 82 after surgery, respectively. The tibiofemoral angle changed from preoperative varus 5.7° to postoperative valgus 5.4°. The complications were 30 knees (13.8%, 27 patients) of early loosening of the femoral component on X-ray, 2 instabilities, 2 periprosthetic fractures and 1 failure of extensor mechanism. Early loosening (30 knees) was found at mean 24 months after operation. Among these cases, 23 knees were able to squat, 5 knees to flex over 130°, 1 knee upto 115° and 1 knee upto 95°. Seven knees (3.2%, 6 patients) were revised at mean 49 months after index operation.

The results after Nexgen^® LPS-flex TKA were satisfactory in terms of ROM, but relatively high incidence of early loosening of the femoral components occurred, which might be associated with passive-maximal flexion activity, such as squatting or kneeling.