Risk avoidance of screw-induced suprascapular nerve injury in arthroscopic Latarjet procedure and reliable anatomical landmark analysis of Latarjet surgery.

OBJECTIVE: Shoulder dislocation represents a prevalent category within joint dislocation, accounting for about 40% of all joint dislocations, and anterior dislocation stands out as the prevailing type. It has been reported that in 1.6% of patients, the Latarjet procedure performed under arthroscopy involves transferring the coracoid process to the anterior-inferior aspect of the glenoid and fixing it with two bicortical screws. The tip of the screws may impinge the suprascapular nerve located behind the scapula, resulting in shoulder pain and weakness. This study was performed to analyze the risk of suprascapular nerve (SSN) injury caused by bicortical screws during arthroscopic Latarjet surgery and to identify reliable anatomical landmarks for Latarjet surgery.

MATERIALS AND METHODS: Dissection was conducted on 23 fresh adult intact shoulder joint specimens, and the experimental protocol complied with the hospital's ethical requirements for research. Using the glenoid clock face as a reference, the distances between the suprascapular nerve and the anterior edge of the glenoid were measured at the 12:00, 11:00, 10:00, and 9:00 positions, as well as at the level of the suprascapular notch and the level of the spinoglenoid notch. The distances between the suprascapular nerve and the narrowest point of the glenoid rim and the clock scale were recorded. The scapula was divided into three zones, and the number of nerve branches in each zone was recorded. The collected data were subjected to statistical analysis. The suprascapular nerve trunk and branches were marked using radiopaque lines, and measurements were taken at three positions in computed tomography horizontal scans: the suprascapular foramen, the spinoglenoid notch, and the point of entry of the outermost nerve branch into the muscle.

RESULTS: The suprascapular nerve originates from the brachial plexus, passes downward and backward through the suprascapular foramen, closely adheres to the bone surface, and runs outward and downward deep to the supraspinatus muscle. The distances between the suprascapular nerve and the glenoid rim at the 12:00, 11:00, 10:00, and 9:00 positions were 335.18±2.31 mm, 28.23±3.47 mm, 22.32±2.78 mm, and 22.12±2.07 mm, respectively. There was a mean of 1.12 nerve branches in zone 1, 2.86 in zone 2, and 3.64 in zone 3. In the neutral position of the shoulder joint, the horizontal distance between point A and the axillary nerve was 27.37 (19.80, 34.55) mm, and the vertical distance was 16.67 (12.85, 20.35) mm.

CONCLUSIONS: The use of bicortical screws, especially upper screws, for Latarjet fixation at the level of the spinoglenoid notch, is associated with the risk of suprascapular nerve injury. The narrowest distance between the glenoid rim and the suprascapular nerve was found between 9:00 and 9:30 at the glenoid clock surface. Therefore, caution should be exercised when performing any procedure related to this area. Overall, the Latarjet procedure is a reliable and effective surgical technique, providing benefits such as favorable positioning of the coracoid graft and low bone absorption rate, while also avoiding the potential for suprascapular nerve injury.