Early Clinical Outcomes (ECO) in the Era of Rapid Recovery Total Joint Arthroplasty: A Comparative Evaluation of Three Bearing Surfaces.

Background and objective Outpatient total knee arthroplasties (TKAs) for low-risk patients are growing in popularity, thanks to expedited recovery and reduced hospital stays. Early postoperative pain reduction has been associated with improved long-term functional outcomes. This study aimed to compare three knee implant systems - posterior-stabilized, medial-pivot, and rotating platform cruciate-retaining (RPCRF) - in terms of their impact on early postoperative pain and opioid use. Methods A retrospective analysis was conducted, involving 94 posterior-stabilized TKAs, 104 medial-pivot TKAs, and 101 RPCRF TKAs by a single surgeon at two hospitals from June 2020 to March 2022. Pain levels per the Numerical Rating System were obtained from the patients' preoperative and postoperative visits at two weeks, six weeks, and 12 weeks. The daily milligram morphine equivalents (MME) in opioid-naive patients were calculated and compared between the three systems. The Kruskal-Wallis and Dunn tests were employed for all calculations to obtain p-values.  Results Posterior-stabilized knees had a significantly larger reduction in pain levels compared to medial-pivot and RPCRF systems at two and six weeks postoperatively. There were no significant differences at the 12-week assessment. The daily MMEs prescribed were similarly reduced with posterior-stabilized knees at two and six weeks, with no difference at 12 weeks. Conclusions Our findings suggest that posterior-stabilized knee implants may offer superior short-term pain reduction and reduced opioid use requirements after outpatient TKA. Further research with randomized and blinded prospective trials is needed to elucidate improvements in patient satisfaction and functional outcomes.