Better functional outcome after single-radius TKA compared with multi-radius TKA.

Purpose: To determine whether the design of the femoral component influenced patient outcomes.

Methods: Two hundred and thirty-seven patients were randomized to compare functional outcomes between single-radius TKA (SR, 118 patients) and multi-radius TKA (MR, 119 patients) with a minimum follow-up of 5 years. Prospective pre- and postoperative assessments were performed by the clinical and radiological criteria of the Knee Society Score (KSS), WOMAC and Short-Form 12 (SF12) questionnaires. The extension mechanism was assessed based on the quadriceps strength and chair test. Patient satisfaction was also assessed.

Results: The median follow-up was 5.7 (range 5-7) years. At last follow-up, significant better KSSs (p = 0.001), range of motion (p = 0.001), extension lag (p = 0.020), quadriceps strength (p = 0.004), chair test (p = 0.032) and WOMAC pain (p = 0.002) were found in the SR group. Moreover, the improvements of these variables were early in the SR group (from 6 postoperative months). There were no significant differences in WOMAC function or SF12 physical and mental components. The revision rate and implant survival were similar in both groups. Satisfaction rate was significantly higher in SR group (p = 0.032).

Conclusion: This study shows better results with SR cruciate-retaining femoral component than MR component. The use of SR system is recommended because, although the clinically relevant differences were moderate, the functional improvement was earlier and the patient satisfaction higher with this design.

Level Of Evidence: Therapeutic study, Level I.