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Published on: May 5, 2023
Comparison of mobile-bearing and fixed-bearing total knee arthroplasty in patients with severe varus deformity: A
Mohammad Parhamfar1, Amirarsalan Armanfar1, Armin Adibi1,2
1Department of Orthopedic Surgery, Isfahan University of Medical Sciences, Isfahan, Iran.
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.
