Kinematic femoral alignment with gap balancing and patient-specific instrumentation in total knee arthroplasty: a randomized clinical trial

Hagen Hommel, Matthew P. Abdel, Carsten Perka

While patient-specific instrumentation (PSI) in total knee arthroplasty (TKA) allows for transfer of the preoperative plan onto bony landmarks, the soft tissue balancing is not affected. The goals of this randomized clinical trial were to compare PSI and the measured resection technique (conventional) with PSI and the gap balancing technique. Fifty patients were randomized to TKA with conventional PSI (PSI-S) (n = 25) or to PSI with additional gap balancing (PSI-GB) (n = 25). All patients were clinically examined at 3 and 12 months postoperatively. Data on the range of motion, the Knee Society Score, the Western Ontario and McMasters Universities Osteoarthritis Index, the High-Flexion Knee Score (HFKS), and the Forgotten Joint Score (FJS) were compiled at follow-up. Statistically significant improvements were found for all clinical parameters in the PSI-GB group compared to the PSI-S group at 3 months postoperatively and for FS, FJS, and HFKS at 12 months. However, the relevance of these differences, as well as their effect on long-term outcomes, needs to be evaluated further. In conclusion, patient-specific instrumentation combined with gap balancing yielded good early clinical outcomes.