Learning curve for intraoperative computer navigation in reverse total shoulder arthroplasty by the cumulative sum method

Abstract

Background

Intraoperative navigation facilitates accurate glenoid component placement. However, introducing a new surgical technique inevitably entails a learning curve for surgeons. This study aimed to determine the learning curve for intraoperative navigation in reverse total shoulder arthroplasty (RSA).

Methods

Fifty-two consecutive patients were analyzed who underwent RSA using the ExactechGPS navigation system between January 2020 and June 2023. Total operation time and time for each surgical stage (bony landmark time, baseplate implantation time, and screw insertion time) were recorded in the navigation system. After surgery, glenoid inclination and version were measured using preoperative planning software, and the deviations in inclination (ΔInc) and version (Δver) from the preoperative plan were investigated. The correlation between the chronological case number and the study variables was evaluated. The cases were divided chronologically into groups I-V (I-IV, 10 cases; V, 12 cases) and compared for operation time, blood loss, and baseplate positioning.

Results

Total operation time trended downward (R² = 0.20, P < .001) from 124.9 ± 10.2 minutes in group I to 126.8 ± 22.7 minutes in group II, 121.5 ± 16.0 minutes in group III, 108.6 ± 13.3 minutes in group IV, and 106.9 ± 10.6 minutes in group V, with a significant difference between groups I and V (P = .035). Screw insertion time also trended downward (R² = 0.16, P < .001); the difference between group I and groups IV and V was significant (I vs. IV, P = .044; I vs. V, P = .017). No significant differences in trends were found in the other stages (bony landmark time, R² = 0.02, P = .37; baseplate implantation time, R² = 0.07, P = .08) or in blood loss. For baseplate positioning, the mean deviation of the achieved inclination from that planned was 2.5° (range, 0°-7.6°). The mean deviation of the achieved version from that planned was 2.7° (range, 0°-8.4°). There was no significant difference in Δinc or Δver among the groups. No learning curve was observed in terms of Δinc (R² = 0.05, P = .09) or Δver (R² = 0.006, P = .59).

Conclusion

Total operation and screw insertion times in RSA trended downward following the introduction of intraoperative navigation. In our experience, about 30 cases were required to shorten the operation time. The learning curve for intraoperative navigation resulted in high accuracy within 3° for both inclination and version immediately after its introduction.