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BackgroundThe aim of this study was to determine if there were significant differences in glenohumeral joint morphology between North American and East Asian populations that may influence sizing and selection of shoulder arthroplasty systems.MethodsComputed tomography reconstructions of 92 North American and 58 East Asian patients were used to perform 3-dimensional measurements. The proximal humeral position was normalized in all patients by aligning it with the scapular plane utilizing anatomic landmarks. Measurements were performed on the humerus and scapula and included coronal and axial humeral head radius, humeral neck shaft and articular arc angles, glenoid height and width, and critical shoulder angle. Glenohumeral relationships were also measured and included lateral distance to the greater tuberosity and acromion, abduction lever arm, and acromial index. Parametric and nonparametric statistical analyses were used to compare population metrics.ResultsEast Asian glenohumeral measurements were significantly smaller for all linear metrics (p < 0.05), with the exception of acromial length, which was greater than in the North American cohort (p < 0.001). The increase in acromial length affected all measurements involving the acromion including abduction lever arms. No difference was found between the neck shaft and articular angular measurements.ConclusionsThe East Asian population exhibited smaller shoulder morphometrics than their North American cohort, with the exception of an extended acromial overhang. The morphologic data can provide some additional factors to consider when choosing an optimal shoulder implant for the East Asian population, in addition to creating future designs that may better accommodate this population.

Failed internal fixation of a fracture of the proximal humerus produces many challenges with limited surgical options. The aim of this study was to evaluate the clinical outcomes after the use of a reverse shoulder arthroplasty under these circumstances. Between 2007 and 2012, 19 patients (15 women and four men, mean age 66 years; 52 to 82) with failed internal fixation after a proximal humeral fracture, underwent implant removal and reverse shoulder arthroplasty (RSA). The mean follow-up was 36 months (25 to 60). The mean American Shoulder and Elbow Score improved from 27.8 to 50.1 (p = 0.019). The mean Simple Shoulder Test score improved from 0.7 to 3.2 (p = 0.020), and the mean visual analogue scale for pain improved from 6.8 to 4.3 (p = 0.012). Mean forward flexion improved from 58.7° to 101.1° (p < 0.001), mean abduction from 58.7° to 89.1° (p = 0.012), mean external rotation from 10.7° to 23.1° (p = 0.043) and mean internal rotation from buttocks to L4 (p = 0.034). A major complication was recorded in five patients (26%) (one intra-operative fracture, loosening of the humeral component in two and two peri-prosthetic fractures). A total of 15 patients (79%) rated their outcome as excellent or good, one (5%) as satisfactory, and three (16%) as unsatisfactory. An improvement in outcomes and pain can be expected when performing a RSA as a salvage procedure after failed internal fixation of a fracture of the proximal humerus. Patients should be cautioned about the possibility for major complications following this technically demanding procedure.

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