Summary
Pre-operative planning should include a CT based assessment of glenoid and coracoid dimensions in order to decide the technique of Latarjet procedure and the optimum diameter fixation screws required.
Abstract
Introduction
Congruent arc Latarjet procedure involves rotating the coracoid process so that its inferior surface is flush with the glenoid face, owing to their matching radius of curvature (ROC). However, there has been no cadaveric study to actually measure and compare the ROC of coracoid with glenoid, especially in Asian population.
Materials And Methods
44 shoulders were dissected in 24 cadavers to measure usable length of coracoid process, width, height, ROC of coracoid and glenoid as well as ulnar length (as proxy of cadaver height). Critical coracoid height and length were estimated based on screw sizes of 2.7 mm, 3.5 mm, 4 mm and 4.5 mm, and pair concordance between height and length calculated. ROC of coracoid and glenoid were compared to measure extent of congruency.
Results
The mean usable length of coracoid process, width and height at mid-point were 21.8 mm, 13.7 mm and 8.6 mm, respectively. Out of the different screw sizes, 2.7 mm screws were found safe in 82% shoulders. 24 coracoid-glenoid pairs fulfilled the operational definition (≤5mm) of congruency while rest 20 were seemingly incongruent chiefly due to coracoid variations, with mean ROC difference 4.13 mm (95% CI 1.51 - 6.74 mm). The ulnar length was significantly smaller in the incongruent ROC group (p=0.0002).
Conclusions
The available length as well as height of the transferred coracoid must be considered when deciding optimum diameter fixation screws in Latarjet procedure. Owing to smaller anatomic dimensions of coracoid in Asian population, 2.7 mm screws provide the safest fixation option. Also, the ROC of coracoid and glenoid do not match in substantial proportion of the cadavers. Pre-operative planning should include a CT based assessment of glenoid and coracoid dimensions in order to decide the technique of Latarjet procedure and the optimum diameter fixation screws required.