The Latarjet Procedure May Induce Pathokinematics with Posterior Humeral Head Subluxation: An Experimental Dynamic Radiostereometric Study.

Abstract

The effectiveness of the Latarjet procedure in stabilizing the glenohumeral joint (GHJ) in the abducted and externally rotated position is well documented. However, evidence of its ability to restore the GHJ kinematics in other positions and without anterior-directed load is sparse. The purpose of this study was to evaluate the GHJ kinematics, throughout external rotation, following the Latarjet procedure in shoulders with 15% anterior glenoid bone loss. Eight human donor arms were examined using dynamic radiostereometry during GHJ external rotation with anterior-directed loads of 0 to 30 N. Kinematics, measured on the basis of the humeral head center and the contact point relative to the glenoid, were assessed at 30° and 60° of GHJ abduction for 3 conditions: the native GHJ, 15% glenoid bone loss, and following the Latarjet procedure. Following the Latarjet procedure, the humeral head center and contact point were up to 9.7 mm (95% confidence interval [CI], 0.5 to 18.8 mm) more posterior and 7.4 mm (95% CI, 0.3 to 14.4 mm) more superior compared with 15% glenoid bone loss. With a 30 N anterior-directed load, the contact point was up to 4.4 mm (95% CI, 2.4 to 6.4 mm) more anterior compared with 15% glenoid bone loss. No significant differences in kinematics between the native GHJ and following the Latarjet procedure were observed with anterior-directed load application. However, without an anterior-directed load, the humeral head center and contact point were up to 7.9 mm (95% CI, 2.3 to 13.5 mm) more posterior and 6.1 mm (95% CI, 0.0 to 12.2 mm) more inferior following the Latarjet procedure compared with the native GHJ. With anterior-directed loading, the Latarjet procedure to treat 15% glenoid bone loss restored the native GHJ kinematics, with the largest stabilizing effect at the end-range external rotation. However, without anterior-directed loading, the humeral head center and contact point were more posterior and inferior following the Latarjet procedure than in the native GHJ, suggesting potential excessive posterior humeral head translation. Posterior subluxation of the humeral head during resting and non-loaded activities following the Latarjet procedure may be a concern in terms of future posterior glenoid cartilage wear and GHJ osteoarthritis. However, these results need to be confirmed in a clinical setting.