Snapping scapula syndrome (SSS) is characterized by a ‘‘snapping’’ sensation of the scapulothoracic articulation caused by bony and/or soft tissue impingement. When symptomatic, SSS is usually accompanied by bursal inflammation. While obvious bony abnormalities such as osteochondromas can lead to bony impingement and SSS, these cases are rare. SSS is mostly seen in normal- appearing scapulae without obvious bony abnormalities and is often associated with trauma or participation in sports leading to muscular imbalances and abnormal scapula positioning. Nonoperative management is the initial treatment choice and is successful in approximately 75% of cases. If nonoperative measures fail to provide a sufficient relief of symptoms, then surgery consisting of bursectomy and partial scapulectomy of the superomedial angle (SMA) is indicated. Initial surgical procedures were performed open but have been widely replaced by minimally invasive arthroscopic techniques because of the advantages of faster recovery time, less cosmetic defects, and preservation of muscular attachments. The majority of patients are satisfied with the outcomes of partial scapulectomy; however, occasionally, recurrent symptoms warrant revision surgery with additional scapular resection.

To date, the amount of scapular resection of the SMA needed to achieve adequate scapulothoracic space decompression (SSD) is not known. There are varying amounts of resection noted in the literature; 2-cm (superior to inferior) by 3-cm (medial to lateral) triangular resection is commonly performed but may vary depending on the size of the scapula and the experience of the surgeon. The bony anatomy of a scapula varies among the population, and recent studies have shown a possible relationship of several bony parameters to the development of SSS in patients. The scapula shape, medial scapula corpus angle (MSCA), costomedial angle, and anterior offset have all been implicated in disease occurrence and severity. Despite the identification of these bony parameters, it remains unclear if, and how, these influence the effect of bony resection. While only certain types of the scapula shape and MSCA seem to affect the scapulothoracic space, as these measurements reflect the bony architecture below the scapula spine, the anterior offset and costomedial angle appear to have a direct relationship with the anatomy that determines the scapulothoracic space.

The aim of this study was to evaluate the effectiveness of partial scapulectomy and the influence of the scapula shape, MSCA, costomedial angle, and anterior offset on SSD using a cadaveric model. It was hypothesized that the anterior offset and costomedial angle would correlate with the amount of bony resection needed to achieve adequate SSD. Furthermore, it was hypothesized that the MSCA and scapula shape, despite being predictors of the occurrence of SSS, would not affect the SSD achieved.

Full Article: A Cadaveric Model Evaluating the Influence of Bony Anatomy and the Effectiveness of Partial Scapulectomy on Decompression of the Scapulothoracic Space in Snapping Scapula Syndrome

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