| Objective:To evaluate the occurrence mechanism of coracoacromial arch impingement syndrome and related prevention and treatment,we observed the anatomical structure of coracoacromial arch and the change of coracoacromial arch space in the shoulder dissection specimens in different positions。Materials and Methods:Sixteen shoulders of cadavers without any kind of shoulder pathology were dissected.All specimens are ruled out the visible disease.Gauged the distance of insertion of the supraspinatus on greater tuberosity of humerus to anterolateral margin of acromion(ACS),the distance of insertion of the supraspinatus on greater tuberosity of humerus to the midpoint of lateral side of coracoacromial ligament(CAS),the maximal overlap distance between greater tuberosity of humerus and coracoacromial ligament,and spatial relationship between supraspinatus and subacromial space in different positions including 0°neutral position,abduction 30 °,60°,90 °,120 °,150.Then the forward head,rear bottom,medial border and lateral border of coracoacromial ligament,and length and height of acromion were measured.Results:ACS values during abduction 60°to 120°are significantly lesser than 0°,abduction 30° and 150°(P<0.01).There was no statistically significant difference in ACS values at three different positions of abduction 60°,90°,and 120°(P>0.05).The CAS value during abduction 60° to 120°was significantly lesser than 0°,abduction 30°and 150°(P<0.01).There was no statistically significant difference in the CAS values at three different positions of abduction 60°,90°,and 120°(P>0.05).The maximal overlap distance between greater tuberosity of humerus and coracoacromial ligament was 1.528±0.0.070cm.The supraspinatus tendon located on the lateral of the shortest distance between humerus and acromion at initial abduction 0°-30°while the tendon deflected to posteromedial of the shortest distance between humerus and acromion at abduction 150°positions.The supraspinatus tendon just go through between acromion and humerus at abduction 90°-120°positions while the tendon located under the coracoacromial ligament.The forward head,rear bottom,medial border and lateral border of coracoacromial ligament were 4.006±0.208cm,2.468±0.208cm,3.996±0.166cm and 4.603±0.210cm respectively.The length and height of acromion were 4.150±0.024cm and 2.520±0.012cm.Conclusions:1.,The coracoacromial arch gap was relatively small when shoulder joint abducted 60 °-120°,which was prone to cause the impingement.So we presented the suggestion that patient of SIS should avoid such movement,to prevent aggravating the disease deteriorated.2.By investgating the anatomical structure of the coracoacromial arch,we provided data support for how to fully release and shape the coracoacromial arch. |
