Minor or occult shoulder instability: an intra-articular pathology presenting with extra-articular subacromial impingement symptoms

Purpose Disruption in the balance of shoulder stability can produce a widely varied spectrum of clinical symptoms, ranging from minor shoulder instability to frank shoulder dislocation, followed by recurrent instability. In this study, a series of patients suffering from minor shoulder instability, all with clinical signs of preoperative subacromial impingement associated with instability, were treated. The shoulder instability alone was addressed, with the aim of eliminating the clinical symptoms of subacromial impingement and pain. Material In this study, 20 patients with minor shoulder instability, presenting with subacromial impingement symptoms, underwent arthroscopic treatment to address capsule-labral pathology. All patients underwent a preoperative assessment by one independent physiotherapist, using Constant and WOSI scores, as well as the Castagna test, on both the affected and non-affected sides. The Hawkins test and subacromial pain in 90A degrees of abduction and internal rotation were also evaluated. All patients followed the same rehabilitation protocol by a second physiotherapist. All patients were followed up at 6, 12 and 24 months postoperatively by the same independent physiotherapist. Results We observed that 20/20 patients had a positive Hawkins sign at > 20A degrees of internal rotation preoperatively, while 4/19 had a positive Hawkins sign-all with less pain-at the 24-month follow-up (P < 0.0001). Moreover, 20/20 had a positive Castagna test preoperatively, while 1/20 had a positive Castagna test at the 24-month follow-up. In terms of shoulder scores, at 24 months, the Constant score had improved from a median value of 70 (51-91) preoperatively to a median value of 91 (86-100). The median WOSI score was 48.3 (12.7-78.6) preoperatively and improved to 84.9 (39.5-98.5) at 24 months postoperatively. Conclusion Minor shoulder instability is an intra-articular pathology presenting with extra-articular subacromial impingement symptoms. By treating the intra-articular pathology, the extra-articular symptoms can be relieved in the vast majority of patients. Level of evidence III.