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Published on: March 1, 2024
Equivalent Functional Outcomes in Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty for Knee
Junwei Soong1, Yongqiang Jerry Chen1, Youheng Ou Yang1
1Department of Orthopedic Surgery, Singapore General Hospital, Singapore.
Background:
Cruciate-retaining (CR) total knee arthroplasty (TKA) is generally avoided in knees with severe fixed flexion deformity (FFD). The need for additional distal femoral resection, posterior soft-tissue releases, and gap balancing typically favors posterior stabilized (PS) implants. This study compared CR- and PS-TKA in severe FFD by evaluating clinical and patient-reported outcomes at two years: (1) range of motion (ROM), (2) Knee Society Score, (3) Oxford Knee Score, (4) Short-form 36 physical and (5) mental component scores.
Methods:
Patients who had severe preoperative FFD ≥ 15° from our institution's TKA registry were propensity-matched according to age, sex, body mass index, and preoperative scores. A total of 294 knees (147 CR-TKAs and 147 PS-TKAs) were matched and analyzed. Patients were evaluated preoperatively, at six months, and at two years. Postoperative manipulation under anesthesia was recorded.
Results:
Both groups achieved significant correction of FFD at two years (CR-TKA: 20.8° [95% confidence interval (CI), 19.7 to 21.9] to 4.0° [95% CI, 3.1 to 4.9]; PS-TKA: 19.9° [95% CI, 19.0 to 20.8] to 3.8° [95% CI, 3.0 to 4.6]; both P < 0.001) with no intergroup differences (P = 0.534). All patient-reported outcomes improved significantly from baseline (P < 0.001) and were comparable between groups. The PS-TKA achieved greater knee flexion and overall ROM (both P < 0.001), but demonstrated more anteroposterior laxity ≥ five mm (P < 0.05). Stair-climbing functions and manipulation under anesthesia rates were comparable (P > 0.05).
Conclusions:
The CR-TKA achieved outcomes comparable to PS-TKA in knees with severe FFD, with deformity correction maintained at two years. Although PS-TKA provided greater knee ROM, CR-TKA demonstrated lower anteroposterior laxity. These differences did not compromise functional outcomes. Both CR-TKA and PS-TKA remain viable options for patients who have severe FFD when careful intraoperative balancing is attained.
