Instability after arthroplasty of the shoulder is difficult to correct surgically. Soft-tissue procedures and revision surgery using unconstrained anatomical components are associated with a high rate of failure. The purpose of this study was to determine the results of revision of an unstable anatomical shoulder arthroplasty to a reverse design prosthesis. Between 2004 and 2007, 33 unstable anatomical shoulder arthroplasties were revised to a reverse design. The mean age of the patients was 71 years (53 to 86) and their mean follow-up was 42 months (25 to 71). The mean time to revision was 26 months (4 to 164). Pain scores improved significantly (pre-operative visual analogue scale (VAS) of 7.2 (sd 1.6); most recent VAS 2.2 (sd 1.9); p = 0.001). There was a statistically significant increase in mean active forward elevation from 40.2° (sd 27.3) to 97.0° (sd 36.2) (p = 0.001). There was no significant difference in internal (p = 0.93) or external rotation (p = 0.40). Radiological findings included notching in five shoulders (15%) and heterotopic ossification of the inferior capsular region in three (9%). At the last follow-up 31 shoulders (94%) were stable. The remaining two shoulders dislocated at 2.5 weeks and three months post-operatively, respectively. According to the Neer rating system, there were 13 excellent (40%), ten satisfactory (30%) and ten unsatisfactory results (30%). Revision of hemiarthroplasty or anatomical total shoulder replacement for instability using a reverse design prosthesis gives good short-term results.

Cite this article: Bone Joint J 2013;95-B:668–72.

Dislocation of the shoulder may occur during seizures in epileptics and other patients who have convulsions. Following the initial injury, recurrent instability is common owing to a tendency to develop large bony abnormalities of the humeral head and glenoid and a susceptibility to further seizures. Assessment is difficult and diagnosis may be missed, resulting in chronic locked dislocations with protracted morbidity. Many patients have medical comorbidities, and successful treatment requires a multidisciplinary approach addressing the underlying seizure disorder in addition to the shoulder pathology. The use of bony augmentation procedures may have improved the outcomes after surgical intervention, but currently there is no evidence-based consensus to guide treatment. This review outlines the epidemiology and pathoanatomy of seizure-related instability, summarising the currently-favoured options for treatment, and their results.

The outcome of an anatomical shoulder replacement depends on an intact rotator cuff. In 1981 Grammont designed a novel large-head reverse shoulder replacement for patients with cuff deficiency. Such has been the success of this replacement that it has led to a rapid expansion of the indications. We performed a systematic review of the literature to evaluate the functional outcome of each indication for the reverse shoulder replacement. Secondary outcome measures of range of movement, pain scores and complication rates are also presented.

The treatment of a chronic posterior dislocation of the shoulder is often determined by the size of the associated impression fracture of the humeral head. Our hypothesis was that patients with a chronic unreduced posterior dislocation of the shoulder and a defect in the humeral head involving between 25% to 50% of the articular surface, would do better if reconstructed with an allograft from the femoral head rather than treated by a non-anatomical reconstruction. We reviewed ten men and three women with a mean age of 42 years (36 to 51) at a mean follow-up of 54 months (41 to 64) who had this procedure. At follow-up, nine had no pain or restriction of activities of daily living. Their mean Constant-Murley shoulder score was 86.8 (43 to 98). No patient had symptoms of instability of the shoulder.

Reconstruction of the defect in the humeral head with an allograft provides good pain relief, stability and function for patients with a locked, chronic posterior dislocation where the defect involves between 25% and 50% of the circumference of the articular surface.