Summary

Imageless robotic handpiece-assisted total knee arthroplasty is associated with a learning curve for operative time that might be longer than reported in current literature and implementation of the intra-operative plan is accurate for implant placement and limb alignment except for the tibial component’s sagittal slope.

Abstract

Purpose

The use of robotics-assisted techniques is increasing in total knee arthroplasty (TKA). The adoption of any new step in surgery is associated with a learning curve and potentially associated with extra complications. The aim of this study was to determine the learning curve necessary to minimize the time of surgery and to evaluate the accuracy of component and limb alignment after imageless, robotic handpiece-assisted TKA.

Materials And Methods

In a prospective case-control study, the first 100 consecutive robotic-assisted (RA) TKAs performed by a single surgeon were analysed and compared to 100 consecutive conventional TKAs operated in the same period. Operative times, implant and limb alignment (comparing intra-operative plan with post-operative alignment) and robot-related complications were evaluated. Cumulative summation (CUSUM) analyses were used to assess learning curves for operative time and implant alignment in RA TKA.

Results

4 RA TKA cases had to be completed with conventional instrumentation due to challenges faced in the RA system workflow, including registration errors. The learning curve for operative time when using the imageless robotic system for TKA was completed after 16 cases. Complete normalization of operative times, equalling conventional TKA time was not seen even after 100 cases. The learning curve did not influence the accuracy of component or limb alignment. The coronal HKA, LDFA, MPTA and sagittal femoral component placement showed an average deviation of 0.90 (SD 2.1), 0.40 (SD 1.4), 0.60 (SD 1.1) and 0.50 (SD 2.7) from the intra-operative plan. The post-operative tibial component sagittal placement showed a significant deviation of 1.60 (SD 2.4) from the intra-operative plan. No minor or major robot-related complications were observed.

Conclusion

Imageless robotic handpiece-assisted TKA is associated with a learning curve for operative time that might be longer than reported in current literature. Implementation of the intra-operative plan was accurate for implant placement and limb alignment except for the tibial component’s sagittal slope.