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Certain elements of condition remain contested among experts

Subacromial impingement syndrome (SIS) is one of the most common causes of shoulder pain and represents a number of pathologies, including subacromial bursitis, rotator cuff tendinopathy and partial- or full thickness rotator cuff tears. Determining the exact etiology for pain can be challenging due to the interplay of pathology in SIS, which has led to debate. One debated matter is the etiology of rotator cuff disease and its relationship to SIS: some claim it's due to primary external compression and others say it comes from intrinsic tendon degeneration. Despite controversies, most investigators believe external compression from the anterior acromion, coracoacromial ligament (CAL), and acromioclavicular joint plays a significant role in rotator cuff disease. Differing views also exist on the best ways to diagnose SIS and whether or not surgery is necessary. To address these matters, a review was conducted that defined current knowledge on the subject and sought to clear up questions with supporting evidence.

Etiologies and diagnostic tools for SIS

As stated above, the debated connection between SIS and rotator cuff disease consists of those supporting primary extrinsic compression and those supporting intrinsic tendon degeneration. Intrinsic supporters agree the acromion does play a role in SIS, as extrinsic supporters do, but they say the primary, inciting factor in SIS stems from weakness and damage to the supraspinatus. In actuality, researchers say, SIS is likely multifactorial, involving both. An accurate diagnosis requires a thorough history and physical exam, plus appropriate imaging. Physical exams should include an evaluation of range of motion (ROM), rotator cuff strength and provocative testing. Radiographs should be obtained to evaluate for bony abnormality of the coracoacromial arch, and should include AP and Grashey views, as well as outlet and axillary views. MRIs are also helpful, as they provide detail of potential sites of SIS through the supraspinatus outlet, and may also demonstrate findings of subacromial sub-deltoid bursitis.

Nonsurgical vs. surgical management

The best course of treatment for SIS is also debated, with options including injections, physical therapy (PT) and multiple surgeries. Nonsurgical management, which is successful in most patients, usually consists of PT focused on decreasing pain, and improving function, ROM and strength, and is sometimes supplemented with a subacromial cortisone injection. Some recent studies have supported the effectiveness of nonsurgical treatment of this sort. Surgery should be considered only in patients with persistent pain who don't recover with nonsurgical treatment, and the type of surgery should be determined based on the surgeon's assessment. While some recent literature has shown debridement and arthroscopic acromioplasty to be successful, no high-quality trials have compared these outcomes to that of conservative treatment. Therefore, more high-quality research on the treatment and diagnosis of SIS is needed, and the course of treatment should remain nonsurgical until a lack of recovery is seen in patients.

-As reported in the Nov. '11 edition of the American Academy of Orthopaedic Surgeons