Comparison of mobile-bearing and fixed-bearing total knee arthroplasty in patients with severe varus deformity: A triple-blind randomized controlled trial.

BACKGROUND

Total knee arthroplasty (TKA) is a common intervention for end-stage knee osteoarthritis, particularly in cases with severe varus deformity. While mobile-bearing (MB) prostheses are designed to offer biomechanical advantages over fixed-bearing (FB) implants, their clinical superiority remains debated, especially in complex deformities.

OBJECTIVE

To compare the clinical and radiological outcomes of MB versus FB TKA in patients with severe varus deformity using the same femoral component design.

METHODS

This triple-blind randomized controlled trial included 70 patients with severe varus knee deformity (>5°), who were assigned to MB (n = 35) or FB (n = 35) TKA groups. All surgeries were performed by a single surgeon using a standardized protocol. Primary outcomes included range of motion (ROM), crepitus, alignment (hip-knee-ankle angle), pain (Visual Analogue Scale) and radiographic evaluations at baseline, and 6 months postoperatively.

RESULTS

At 6 months, both groups showed significant improvements in ROM and Visual Analogue Scale (VAS) pain, with no statistically significant differences between them (FB: 121.43 ± 13.53°, MB: 121.71 ± 13.45°, P = 0.92 for ROM and FB: 16.57 ± 11.86°, MB: 20.86 ± 15.02°, P = 0.19 for VAS pain). However, the FB group had significantly greater residual varus alignment (4.85 ± 3.97° vs. 2.17 ± 4.39°, P = 0.008). One case of aseptic loosening occurred in the MB group.

CONCLUSION

In patients with severe varus deformity undergoing TKA, MB implants resulted in improved postoperative alignment but yielded similar short-term functional outcomes compared to FB implants. Longer follow-up is necessary to determine the clinical relevance of these radiological differences.