Evaluating the Impact of Patellar Resurfacing in Medial Stabilized Total Knee Arthroplasty: A Retrospective Cohort Study

OBJECTIVES: Patellar resurfacing in total knee arthroplasty (TKA) remains a debated topic. Medial stabilized (MS) implants have gained popularity in the United States in recent years as they more closely mimic native femoral-tibial and patella-femoral knee kinematics. However, little is known about the effects of patellar resurfacing with a specific round-on-round, one-to-one congruent, medial stabilized implant. The purpose of this study was to evaluate whether patellar resurfacing influences pain, function, patient-reported outcomes, and perioperative outcomes in patients undergoing primary MS TKA with this implant. METHODS: A retrospective cohort study was conducted on 107 patients undergoing primary MS TKA with the Sphere implant (Medacta International, Castel San Pietro, SZ). Patients were divided into resurfacing (R, n = 51) and non-resurfacing (NR, n = 56) groups. Outcomes included pain scores, range of motion (ROM), patient-reported outcome measures (PROMs), and perioperative variables. PROs collected included PROMIS Physical Function and Pain Interference CATs, Knee Society Score (KSS), Visual Analog Scale (VAS) pain score (0-100), Knee injury and Osteoarthritis Outcomes Score (KOOS), Forgotten Joint Score (FJS), patellofemoral pain questionnaire, and the Samsung Medical Center (SMC) patellofemoral scoring system. Comparative statistical analyses were performed using chi-square tests, t-tests, and Mann-Whitney U tests. RESULTS: No significant differences were found in postoperative pain scores (VAS), opioid consumption, or overall PROMs between groups. However, the non-resurfacing group demonstrated greater ROM at 12 months (121.5° vs. 116.4°, p = 0.03) and higher KOOS ADL and symptom subscales. Resurfacing was associated with increased operative time (p < 0.001) and tourniquet time (p = 0.03); hospital LOS was shorter in the resurfacing group by six hours (p < 0.05). CONCLUSION: In MS TKA, patellar resurfacing did not confer significant advantages in pain relief or functional outcomes at one year. These findings support an individualized approach to patellar resurfacing in MS TKA as each technique is deemed non-inferior.