Clinical Effect Of Hooked Acromion In Shoulder Impingement Syndrome Treated With Cutting-block Technique

Background: Shoulder impingement syndrome(SIS)is one of the most common reason for shoulder pain.Two types of shoulder impingement have been described: intrinsic and extrinsic.Extrinsic SIS is mostly caused by abnormalities in the surrounding structure of shoulder joint,resulting in abnormal contact between the acromion or coracoid process.Type III acromion is one of common cause of extrinsic SIS.SIS can be treated conservatively or surgically.Subacromial arthroscopic decompression(SAD)is the most common surgical treatment.SAD can effectively expand the space under the acromion;remove the protruding osteophytes under the acromion,avoiding the mechanical basis of the acromion and rotator cuff during the movement of the shoulder joint;forming a bare bone surface,providing the potential source of mesenchymal stem cells can promote the healing of rotator cuff tendons;remove nociceptive pain fibers in the subacromial space and eliminate the pain.As the critical step of SAD,there are two methods for acromioplasty,lateral approach and posterior approach.The posterior approach is also known as the Cutting-block technique.This technique uses the posterior edge of the acromion as the fulcrum and the posterior acromion slope as the reference plane for trimming the acromion.It provides a fixed bony reference standard during the operation and cooperates with the diameter of the high-speed drill to control the amount of bone removed under the acromion.So as to form an ideal lower surface of acromion,other types of acromion are trimmed to type I acromion.Objective: To explore the clinical effect of posterior SAD using Cutting-block technique to treat refractory shoulder impingement syndrome.How to ensure the accurate judgment of the amount of subacromial bone removed during the operation has become the main intraoperative focus of subacromial decompression.Methods: This study was a postoperative study.From January 2012 to January 2019,31 patients with extrinsic shoulder impingement syndrome caused by a type III acromia were treated,including 11 males and 20 females;(56.3±7.66)years old(range 36-70 years).There were 14 cases of right shoulder and 17 cases of left shoulder with a period of(6.4±3.6)months(range 4 to 21 months).The main symptoms were shoulder pain and dysfunction.The shoulder Y view showed the presence of a type III hook-like acromion.The rotator cuff tear was rule out during arthroscopy.All patients underwent arthroscopic subacromial decompression using Cutting-block technique.Visual Analogue Scale,the university of California at Los Angeles(UCLA)shoulder rating scale(modified),Constant-Murley Score(CMS),and satisfaction rate of surveys were documented before and after surgery.Results: In this study,A total of 31 patients were completely matched the inclusion criteria of this study.The average follow-up time was 16.3±4.3 months(13~28 months).The postoperative patient function score was significantly improved compared with preoperative score.The VAS score was 4.0±0.9 before surgery,and postoperatively,1.2±0.8(t=15.3,p<0.01).The preoperative UCLA score was 11.1±1.8,and postoperatively 32.5±1.8(t=-48.7,p<0.01),among the various sub-items of the patient’s UCLA score,the patient’s shoulder joint pain and function scores were improved compared with preoperatively,and the differences were statistically significant.The CMS was 51.1±4.6 before surgery,and postoperatively 91.4±3.1(t=44.6,p<0.01),Among them,the patient’s subjective pain score and daily activity score,as well as the patient’s shoulder joint function and other sub-scores, compared with preoperatively,patients made improvement through SAD,and the differences were statistically significant.The overall satisfaction of the surgical results was 96.7%.Conclusion: The posterior SAD with the Cutting block technique can form a flat subacromial surface,which can significantly mitigate the patient’s shoulder joint pain,improve shoulder joint function,and play a good role in the treatment of extrinsic SIS caused by hook acromion treatment effect.The posterior SAD with the Cutting block technology can provide the surgeon with an effective quantitative reference for the amount of bone removed during the operation.It is recommended to perform posterior SAD with Cutting block technique for patients with acromion impingement syndrome caused by type III acromion.