Pre-clinical evaluation of a smartphone-assisted navigation system for surgical pin positioning in total knee arthroplasty.

Abstract

Total knee arthroplasty (TKA) success is highly dependent on accurate implant alignment, however, 80% of procedures globally are performed manually. Manual procedures have higher alignment errors compared to robotic platforms and patient-specific instrumentation, yet these have limitations of high cost and intraoperative inflexibility, respectively. This study aimed to evaluate the intraoperative pin positioning accuracy and flexibility of a smartphone-assisted navigation system using CT-derived surgical plans. Three participants used the navigation system to perform 108 guide pin insertions (54 femoral, 54 tibial) on surrogate bone models based on CT-derived surgical plans. Testing included both default mechanical axis targets (0°) and user-selected navigated targets ranging from -3° to 3°. Accuracy was assessed by comparing achieved pin trajectories with the preoperative surgical plan. Median absolute angular deviations achieved ranged from 0.9° to 1.6° across all component-plane combinations, with an overall median deviation of 1.3° (IQR 0.6-2.1°). The proportion of insertions within a predefined ±3° clinical accuracy threshold ranged from 83.3% to 100%, and all component-plane combinations demonstrated deviations significantly within this threshold (p < 0.00001). These findings support the technical feasibility of the smartphone-assisted navigation system for surgical pin positioning under controlled pre-clinical conditions. Further studies will evaluate the navigation system in cadaveric models with experienced orthopaedic surgeon participants.