Latarjet Coracoid Transfer Versus Distal Clavicular Autograft for Anterior Shoulder Instability With Glenoid Bone Loss: A Biomechanical Comparison of 2 Graft Reconstructions in Various Medial Positions.

Abstract

Background: No biomechanical study has established the effect of different graft positions or bone block options on anterior glenohumeral joint stability.

Purpose/hypothesis: The purpose of this study was to compare graft choice (distal clavicular vs coracoid autograft for Latarjet) and position on stability of the bone block for anterior glenohumeral instability. It was hypothesized that both grafts would be comparable if flush with the glenoid but that the sling effect of the Latarjet procedure would lead to greater stability in case of graft medialization.

Study design: Controlled laboratory study.

Methods: Eight cadaveric shoulders were included. Defects stabilized using a distal clavicular graft and a coracoid graft were consecutively positioned at 0, 4, and 8 mm medially. The starting position was determined by the humeral head's being seated at its most medial position on the glenoid surface. Each experiment comprised maximal external rotation and glenohumeral abduction at 60° while applying a constant 50-N medial compressive force to the humerus under all conditions. The conjoint tendon was routed through a split in the subscapularis and loaded with a 5-N weight using a pulley system for all Latarjet trials to simulate the sling effect.

Results: Regarding the clavicular graft, the stability ratio significantly decreased versus the intact condition at all medial offsets (P = .007 for 0 mm, P < .001 for 4 mm, and P < .001 for 8 mm), and it was significantly lower in the 4-mm versus 0-mm position (P = .008), significantly higher in the 4-mm versus 8-mm position (P < .001), and significantly lower in the 8-mm versus 0-mm position (P < .001). Regarding the coracoid graft, the stability ratio was comparable with intact for the 0-mm position (P = .12), while it was significantly lower in the 4-mm and 8-mm positions (P < .001 for both). The distal clavicular graft at 0-mm offset was comparable with the coracoid graft at 0-mm offset.

Conclusion: In shoulders with anterior glenoid bone loss, the coracoid and distal clavicular autografts were biomechanically comparable when placed flush with the glenoid. The distal clavicle at 0-mm offset did not restore stability compared with the intact specimen, but the Latarjet at 0-mm offset was not significantly different from the intact condition.

Clinical relevance: The Latarjet procedure provides higher stability compared with distal clavicular autograft when medialized.