Is There a Need for Arthroscopic Subacromial Decompression in Treating Outlet Impingement Syndrome? Sizing Classification of the Subacromial Space Narrowing and Treatment Guidelines

Background: The arthroscopic acromioplasty procedure for treating outlet impingement aims to remove the subacromial bursa, (which can serve as a pain generator) and any osteophytes on the undersurface of the acromion, which can lead to impingement as well as decompress the subacromial narrowing causing the impingement by removing bone from the lower surface of the anterior acromion. Controversies were lately present in the literature about whether there is a need for anterior acromioplasty in treating outlet impingement [1]. The control of bleeding and the determination of the appropriate amount of bone resection are two common technical difficulties in performing the arthroscopic subacromial decompression. This paper describes a technique to classify the subacromial narrowing and simplifies the procedure while providing more precise bone resection and contouring in cases of outlet Impingement. This technique is based on the arthroscopic sizing classification of the sub-anterior acromion tendon space (SAT space) described by the first author through using a special measuring needle device for measuring the space in standard sitting position under anesthesia and monitoring the decompression. It also presents the relation between subacromial pathology and the size of the narrowing. Material and Methods: The arthroscopy was done in general anesthesia with the patient in a standard sitting position with the arm hanging. Between 2015 and 2020, 410 cases had an arthroscopic measurement for the space between the anterior acromion and the cuff (SAT space) in which 280 out of 410, were cases of more than 6 months therapy resistant outlet impingement syndrome stage II (without cuff tear) and impingement stage III with cuff tear. The other 130 cases were instability and calcific tendonitis. The SAT space is classified to 4 sizes grades, called Sizing Classification. A standard arthroscopic anterior acromioplasty was made depending on the grade of SAT space. An arthroscopic trans-periosteal - muscular suture reconstruction of the origin of the anterior deltoid muscle was done if there was a gap after bone removal. Results: In the study all cases of outlet impingement were only present with SAT space grade 2 -4 , there was no outlet impingement stage II (chronic impingement) or III (impingement with supraspinatus tear) found with a SAT space grade 1, thus the bone removal was only of the amount of bone needed to get a SAT space grade 1 (more than 12 mm). The postoperative results were very promising, no complications were found, and the Neer Score was rated excellent in all 228 out of the 280 impingement cases reexamined with an average follow up period of 6 years and 3 months. Conclusion: The sizing classification is a guide to determine whether there is a need for decompression, and if so, the amount of bone to be removed based on the measuring guide. Thus, it gives more clarity to the controversy presented now in literature. The subacromial decompression based on the sizing classification using the measuring needles eases the operation and standardizes the technique. Closing the defect at the deltoid origin if present, leads to regaining the normal anterior deltoid anatomical origin.