Preoperative flexion does not influence postoperative flexion after rotating-platform total knee arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Rehabilitation Science

Background:

• Preoperative range of motion (ROM) is traditionally considered a key predictor of postoperative ROM after total knee arthroplasty (TKA).
• Mobile-bearing TKA designs are hypothesized to offer improved knee kinematics compared to fixed-bearing designs.

Purpose of the Study:

• To investigate the relationship between preoperative and postoperative flexion in patients undergoing TKA with a posterior-stabilized rotating-platform prosthesis.
• To determine if preoperative ROM influences the degree of flexion achieved after TKA with this specific implant design.

Main Methods:

• A consecutive series of 153 TKAs utilizing a rotating-platform posterior cruciate-substituting design were analyzed.
• Patients were stratified into two groups based on preoperative ROM: Group 1 (< 95°) and Group 2 (> 95°).
• Range of motion (ROM) and Knee Society Score (KSS) were evaluated preoperatively, and at 3 and 12 months postoperatively.

Main Results:

• No significant difference in 12-month postoperative flexion was observed between the two preoperative ROM groups (mean 120° vs. 123°).
• Patients in Group 1 (limited preoperative ROM) demonstrated significantly greater improvements in both ROM (p < 0.001) and KSS (p < 0.05) at 3 months.
• No significant difference in KSS was found between groups at the 12-month follow-up.

Conclusions:

• In this cohort, preoperative ROM was not a reliable predictor of postoperative flexion following TKA with a rotating-platform prosthesis.
• The findings suggest that patients with preoperative knee stiffness may experience greater functional gains with mobile-bearing TKA designs.