Restoration of shoulder kinematics during active throwing after the Latarjet procedure in anterior shoulder instability: A dynamic radiostereometric study

Abstract

Purpose

To evaluate glenohumeral joint (GHJ) kinematics during a throwing motion in patients with anterior shoulder instability before and 1 year after the Latarjet procedure.

Methods

In this prospective study, 13 patients with unilateral, traumatic anterior shoulder instability scheduled for the Latarjet procedure were examined preoperatively and at 1-year follow-up. GHJ kinematics were assessed during a standardized throwing motion using dynamic radiostereometric analysis. Preoperatively, both the injured and contralateral healthy shoulders were assessed. One year post-operatively, only the injured shoulder was assessed. GHJ kinematics were evaluated in six degrees of freedom, including rotations and translations of the humeral head centre and contact point, as well as the glenohumeral contact area, throughout the throwing motion.

Results

Post-operatively, the humeral head centre shifted up to 1.1 mm posteriorly (95% confidence interval [CI]: 0.3–1.9) and 0.4 mm superiorly (95% CI: 0.0–0.7) compared with the injured shoulder and was 1.4 mm (95% CI: −1.2 to 4.1) more posterior compared with the healthy shoulder. The contact point translations showed similar patterns, although not statistically significant. The GHJ contact area increased post-operatively by up to 87.0 mm² (95% CI: 35.9–138.0) compared with the injured shoulder and with no statistically significant difference compared with the healthy shoulder.

Conclusions

The Latarjet procedure produced a posterior–superior shift of the humeral head compared with the preoperative injured shoulder and restored glenohumeral contact area to levels similar to the healthy shoulder during an active throwing motion. These findings support the stabilizing effect of Latarjet procedures under functional, load-bearing conditions relevant to overhead athletes.

Level of Evidence

Level III.