Title : Outpatient Total Knee Arthroplasty (TKA): Comparing all-polyethylene and metal-backed tibial outcomes
Abstract:
Background: All-polyethylene tibial components in Total Knee Arthroplasty (TKA) offer potential cost reduction and eliminate backside wear, with recent evidence suggesting comparable long-term survival to metal-backed components. This retrospective, non-inferiority study evaluated pain outcomes and complications following outpatient primary TKA using all-polyethylene versus metal-backed tibial components.
Methods: A retrospective cohort study was conducted on primary outpatient TKAs performed for osteoarthritis. Exclusion criteria included infection, concomitant procedures, constrained implants, or alternative bearing surfaces. Propensity score matching (1:1 ratio) was employed to minimize selection bias, resulting in 229 patients per group. Pain reduction, assessed using a Numerical Rating Scale (NRS), was the primary outcome. Secondary outcomes included descriptive statistics on implant survival (Kaplan-Meier analysis), arthrofibrosis (flexion <90° or extension deficit >10°), and manipulation under anesthesia (MUA). Propensity score matching demonstrated a reduction in baseline differences between groups for age and Body Mass Index (BMI), with no statistically significant differences in smoking status or laterality (left vs. right).
Results: Preliminary visual analysis of NRS pain scores across defined time intervals (0-2 weeks, 2-4 weeks, 4-6 weeks, 6-12 weeks, 12 weeks-6 months, 6-12 months, 1-2 years, 2-5 years) revealed no clinically significant differences between groups. Mean NRS pain scores for metal-backed TKA were 4.2, 4.4, 3.6, 3.1, 2.5, 2.1, 2.2, and 4.5, respectively. For all-polyethylene TKA, scores were 4.9, 4.5, 3.7, 3.0, 2.5, 2.8, 2.2, and 4.2. Arthrofibrosis rates were 2.6% for all-polyethylene and 5.7% for metal-backed tibias. Three patients in the all-polyethylene group and one in the metal-backed group required MUA. Implant survival in the all-polyethylene group showed one revision at 364 days post-surgery. In the metal-backed group, three patients required revision at 67, 147, and 1052 days post-surgery. Statistical analysis of pain scores is ongoing.
Conclusion: Preliminary findings suggest all-polyethylene tibial components in outpatient TKA demonstrate comparable pain outcomes to metal-backed components, supporting their potential use in cost-conscious settings. While statistical analysis of pain scores is pending, the observed arthrofibrosis rates, despite limited sample size, are consistent with this trend.
