Customized Individually-Made and Conventional Total Knee Implants are associated with Similar Improvements in Patient-Reported Outcomes

Abstract

Background Customized individually-made (CIM) implants aim to reproduce knee kinematics by restoring patient-specific anatomy. There is sparse data comparing outcomes of CIM implants with conventional implants. The purpose of this study was to compare short-term outcomes of total knee arthroplasty (TKA) performed with CIM versus off-the-shelf (OTS) implants. Methods We retrospectively compared clinical outcomes of 123 CIM TKAs with 282 concurrent, matched OTS TKAs performed at a single academic medical center by two high-volume arthroplasty surgeons. All CIM TKA were included. Perioperative outcomes evaluated included hospital length-of-stay (LOS), discharge disposition, and patient-reported outcome measures (PROMs) at baseline, 3 months, and 1 year. Student’s t-tests were used for continuous variables, and chi-squared tests were used for categorical variables. Results Baseline demographics were statistically similar between groups. CIM Baseline WOMAC Pain and Physical Function scores were statistically, but not clinically, better. There were no differences in LOS (CIM 2.19d vs. OTS 2.35d; p=0.30) or proportion discharged home (78.7% vs. 83.5%, p=0.26). There were no differences in WOMAC subscores or the KSS Functional Score at 3-month and 1-year follow-up. The CIM cohort had a statistically significant, but not clinically significant, higher KSS-Function score at 1-year (79.4 vs. 72.6, p=0.02), but the change from preoperative baseline was not significant between groups. Conclusions Compared to traditional TKA implants, CIM implants offered similar improvements and patient-reported outcome scores through the first postoperative year. Longer-term outcomes as well as cost-effectiveness of CIM implants should be studied.