| Objective:The coracoid process was transplanted anteriorly and inferiorly to the glenoid of the shoulder by arthroscopic Latarjet procedure and fixed with two bicortical screws.The tip of the screw behind the scapula can damage the suprascapular nerve,causing pain and weakness in the shoulder joint.The aim of this study was to investigate the threedimensional anatomical relationship between the suprascapular nerve and the scapula and the risk of screw injury to the SSN during Latarjet procedures,describing reliable anatomical landmarks for arthroscopic Latarjet procedures.Methods:Part Ⅰ:(1)12 fresh adult intact shoulder joint specimens were dissected,7 of the 12 specimens were right-handed and 8 were male.In order to study the anatomical relationship between the suprascapular nerve and the scapula,the glenoid surface clock system was used as a reference to measure the suprascapular nerve at 12:00,11:00,10:00,9:00,at the level of the suprascapular notch,and at the level of the spinoglenoid.The distance from the trace level to the anterior rim of the glenoid of the shoulder joint was recorded,and the distance from the narrowest distance between the suprascapular nerve and the glenoid rim and the clock scale were recorded.(2)Define the scapular region and record the number of branches of the suprascapular nerve in each region.Part Ⅱ:Mark the suprascapular nerve with a medical barium line,scan the shoulder joint specimen with computed tomography(CT),import the scan data into Mimics software for3 D reconstruction,and draw the best fitting circle of the glenoid in the 3D model.The glenoid clock system measures the distance from the suprascapular nerve to the anterior edge of the glenoid at 12:00,11:00,10:00,9:00,simulating a coracoid osteotomy,with screws inserted anterior to the glenoid,and the outlet at The narrowest distance from the suprascapular nerve to the glenoid,describes the angle of the screw in the axial and sagittal planes,and defines the safe area behind the scapula where suprascapular injury can be avoided.Results:Part Ⅰ:The suprascapular nerve originates from the brachial plexus,passes through the suprascapular foramen downwards and backwards,closes to the bony surface and goes out and down on the deep surface of the supraspinatus muscle.Bypassing the spino-glenoid notch,it descends inward to the infraspinatus fossa,giving off the infraspinatus branch,which innervates the infraspinatus muscle.The distances from the suprascapular nerve to the glenoid rim at 12:00,11:00,10:00,and 9:00 were 35.15±2.34 mm,28.19±3.42 mm,22.37±2.75 mm,22.06±2.09 mm,respectively.The distance from the level of the superior notch to the glenoid rim was 34.91±6.28 mm,the distance from the level of the spinoglenoid notch to the glenoid rim was 21.02±6.52 mm,and the narrowest distance from the suprascapular nerve to the glenoid rim was 18.82±0.88 mm,this area is located between9:00 and 9:30 in the glenoid.SSN has an average of 1.08 branches in zone 1,2.83 branches in zone 2,and 3.67 branches in zone 3.Part Ⅱ:The mean insertion angle α1 in the axial plane of the superior screw was 19.60°±2.40°(range,16.17°-23.18°),and the mean insertion angle β1 of the screw in the sagittal plane was 17.48°±2.94°(range,12.71°-22.04 °),the mean insertion angle α1 of the inferior screw axial plane was 22.83°±2.34(range,17.58°-24.83°).In the axial plane,as long as the α1angle of the superior screw is less than or equal to 19.60°,the screw does not make contact with the suprascapular nerve.In the sagittal plane,the screw orientation is upward,with an average angle of 17.48° to the horizontal plane.Conclusions:(1)The safe zone of the suprascapular nerve can be determined by the glenoid clock system,which is a reliable intra-articular marker during the Latarjet procedure.The narrowest distance from the glenoid rim to the SSN is found between 9:00 and 9:30,so any procedures related to this area should be performed with caution.(2)Latarjet bicortical screw fixation at the level of the spinoglenoid notch has the risk of damaging the SSN,especially the superior screw.The insertion angle of the upper screw on the axial plane should be less than 19.60°... |
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