Patient-Specific Instrumentation in Total Knee Arthroplasty: Alignment Accuracy and Clinical Scores

Abstract

Background: Patient-specific instrumentation (PSI) uses preoperative CT or MRI to manufacture single-use cutting guides for
total knee arthroplasty (TKA), promising more accurate alignment and lower instrumentation burden than conventional
technique. Objective: To synthesise comparative evidence on PSI accuracy, efficiency, cost, and outcomes relative to conventional
instrumentation and navigated/robotic TKA. Methods: Narrative review of randomised trials, comparative series, and systematic reviews/meta-analyses. Findings: Individual series report fewer coronal outliers with PSI (9-13% versus 22-29% for conventional), but pooled meta-analyses find no significant difference in outliers, operative time, blood loss, or Oxford/WOMAC/KSS scores; navigation and robotics achieve more consistent alignment than PSI. Conclusions: PSI offers workflow convenience but no demonstrated accuracy or outcome advantage over conventional instrumentation, and is outperformed by robotic/navigated techniques on alignment precision.
Keywords: Patient-specific instrumentation; Total knee arthroplasty; Mechanical alignment; Outliers; Knee Society Score;
Robotic surgery