JOA - 2026-04-15 - Journal Article
Do Customized Implants Yield Superior Clinical and Functional Outcomes Compared to Off- the-Shelf Implants in Primary Total Knee Arthroplasty? A Propensity-Matched Analysis.
Ilyas MH, Freeman I, Sampson WT, Afzal S, Kang H, Kwon YM
Topics
Key Takeaway
Customized individually made TKA implants produced equivalent MCID-based PROM improvement and complication rates compared to off-the-shelf implants across all four outcome measures at two years in a propensity-matched cohort of 1,032 patients.
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Summary
This single-institution retrospective study used 1:3 nearest-neighbor propensity score matching to compare PROMIS SF-10a, PROMIS Global Physical, PROMIS Global Mental, and KOOS-PS outcomes between CIM and OTS primary TKA patients. Although CIM patients had higher absolute pre- and postoperative scores on SF-10a, PROMIS Global Mental, and PROMIS Global Physical (P<0.05), the magnitude of score change and proportion achieving MCID were equivalent between groups across all PROMs (P>0.05). Complication rates at 90 days, 1 year, and 2 years were also statistically indistinguishable between cohorts.
Key Limitation
The retrospective single-institution design with non-randomized implant selection introduces indication bias that propensity matching cannot fully eliminate, particularly given the unresolved baseline PROM differences between groups.
Original Abstract
BACKGROUND
Customized individually made (CIM) total knee arthroplasty (TKA) implants are designed using preoperative computed tomography to optimize component fit, mechanical alignment, and joint line restoration. Despite their theoretical advantages, clinical adoption and evidence demonstrating meaningful functional benefits over off-the-shelf (OTS) implants are limited. This study aimed to compare clinical outcomes and rates of achieving the minimal clinically important difference (MCID) in patient-reported outcome measures (PROMs) between CIM and OTS implants using a propensity-matched analysis.
METHODS
A retrospective cohort study was conducted at a single institution following Institutional Review Board approval. Among 2,474 consecutive primary TKAs, 258 CIM and 774 OTS patients were identified using 1:3 nearest-neighbor propensity score matching based on demographic and comorbidity variables. The Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Short Form 10-a (SF-10a), PROMIS Global-Physical, PROMIS Global-Mental, and Knee Injury and Osteoarthritis Outcome Score-Physical Function Shortform (KOOS-PS) was collected for analysis. The proportions of clinically meaningful change were calculated with MCID using the distribution-based method. The 90-day and one- and two-year complication rates were recorded. After matching, there were no differences in baseline demographics between groups (P > 0.05).
RESULTS
Customized TKA patients had higher pre- and postoperative SF-10a, PROMIS Global Mental, and PROMIS Global Physical scores (P < 0.05) and higher preoperative KOOS-PS scores (P < 0.05) when compared to OTS patients. Similar changes in scores and proportions of clinically meaningful improvement and worsening were seen between groups in all PROMs (P > 0.05). Similar 90-day, one-year, and two-year complication rates were present in both groups (P > 0.05).
CONCLUSION
This study demonstrated that CIM implants were associated with similar clinical and patient-perceived outcomes compared to OTS implants when evaluated using MCID-based thresholds. These findings may inform preoperative patient counseling for individuals considering TKA.