Prevalence of anterior knee pain after patellar retention total knee arthroplasty: Comparison of patients with rheumatoid arthritis versus primary osteoarthritis

Objective
The aim of this study was to investigate whether there is an increased risk of anterior knee pain (AKP) after total knee arthroplasty (TKA) without patellar resurfacing in patients with rheumatoid arthritis (RA) versus primary osteoarthritis (OA).

Methods
This study was a retrospective review of 388 patients (577 knees) who underwent TKA without patellar resurfacing between 2003 and 2011, with a minimum of 5 years of follow-up. Patients were divided into two groups: Group OA (273 knees of 206 patients; 83 males, 123 females; mean age: 64.4 (47–87) years) and Group RA (304 knees of 182 patients; 92 males, 90 females; mean age: 50.7 (21–72) years). In the clinical evaluation, the knee range of motion (ROM) and several outcome measures such as The Knee Society Score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and International Knee Documentation Committee (IKDC) scores were used preoperatively and at the final follow-up visit. The quality of life was measured using Short Form (SF)-36 MCS and PCS scores. The primary outcome was the frequency and severity of patient-reported AKP. The AKP Scale was used to determine the severity of AKP.

Results
The IKDC raised from 21.62 (range, 13–29.9) preoperatively to 85.1 (range, 80–88) for group OA and from 21.8 (range, 13–29.9) to 85.2 (range, 81–88) for group RA (p < 0.001). The mean KSS improved from 28.35 (range, 22–38) preoperatively to 90.04 (range, 88–95) for group OA and from 21.9 (range, 18–35) preoperatively to 89.7 (range, 86–95) for group RA. The mean WOMAC increased from 20.61 (range, 17.4–24.2) preoperatively to 95.7 (range, 90.9–97.7) for group OA (p < 0.001) and from 20.2 (range, 16.7–24.2) preoperatively to 95.8 (range, 90.9–98.5) for group RA (p < 0.001). The mean ROM improved from 80.14° (range, 55°–130°) preoperatively to 113.17° (range, 95°–140°) in group OA (P = 0.003) and from 73.4° (range, 10°–130°) to 112.8° (range 90°–140°) in group RA (P = 0.003) postoperatively. The frequency of AKP was 8% in Group OA and 7% in Group RA (p = 0.27). For patients with AKP, the mean AKP Scale was 92.74 (range, 84–98) in Group OA and 93.39 (range, 82–98) in Group RA (p = 0.3).

Conclusion
After TKA without resurfacing the patella, patients with RA were determined to have a similar risk for AKP as those with OA.

Level of evidence Level III, Therapeutic Study.