The function of the shoulder joint has traditionally been evaluated based on range of motion (ROM) in predefined anatomical planes and also by using functional scores, which assessed shoulder function based on the ability to conduct certain activities of daily living (ADLs). However, measuring ROM only in terms of flexion-extension, abduction-adduction and internal-external rotation may under-account for the 3-dimensional mobility of the shoulder joint. Furthermore, functional scores, such as the Oxford shoulder score or American shoulder and elbow surgeons (ASES) score, are subjective measures and are not an accurate assessment of shoulder joint function. In this study, we proposed the use of the globe model of the shoulder joint which can be used to provide an objective measure of the global ROM and also function of the shoulder joint – termed the Global and Functional arc of motion (GAM and FAM). Thirty-three young, healthy male patients (23.7 ± 1.5 years) were recruited and tasked to perform eight ADLs and a full humeral circumduction movement which represented their active global ROM. Reflective markers were placed in accordance to the International Society of Biomechanics (ISB) and optical-based motion capture cameras were used to track relative motion of the dominant humerus with respect to the thorax (i.e. thoracohumeral motion). The GAM and FAM were generated by plotting the thoracohumeral on a spherical coordinate system during global ROM and the eight ADLs respectively. Shoulder joint global ROM and function were quantified by calculating the area enclosed by the closed loop of GAM and FAM respectively. The spherical coordinate system, or more commonly referred to as the globe model, describes thoracohumeral movement using plane of elevation (POE), angle of elevation (AOE) and rotation. In our model, POE and AOE represents longitude and latitude of the globe respectively, and rotation is depicted using a red-green-blue (RGB) colour scale. Overall, subject's GAM of the shoulder joint covered an area of 4.64 ± 0.48 units2 compared to only 1.12 ± 0.26 units2 for the FAM. Subjects only required 24.4 ± 5.7 % of their global shoulder ROM for basic daily functioning. Studies that reduced shoulder joint movement into planar movements (i.e. sagittal, coronal and rotation) do not account for the 3-dimensional nature of the joint and doing so may overestimate the requirement of the shoulder joint for ADLs relative to its ROM in each plane. While others have attempted to use the globe model, such studies tend to reduce the globe into its descriptive angles (i.e. POE, AOE and rotation), reducing its intuitiveness. In contrast, by keeping an intact globe, the proposed globe model was more intuitive and yet capable of quantifying both shoulder joint global ROM and function. Doing so, we found that young healthy subjects only required approximately a quarter of their global ROM of the shoulder joint to complete the most common daily tasks, which was significantly less than what was previously reported

Background. The purpose of this retrospective study was to examine the functional outcomes of patients treated for isolated fracture of the greater tuberosity (GT) and to determine how their outcomes were affected by fracture pattern, treatment choices, associated shoulder injuries, the post fixation displacement of GT fragment and the time delay between injury and fixation. Methods. Forty-eight (28 male and 20 female) patients (mean age 45 years) treated at our institution between 1999–2009 matched our inclusion criteria. Thirty-five patients were treated surgically and 13 conservatively. Functional outcome was assessed using Oxford scores (OS), University of California and Los Angeles (UCLA) rating scale and the shoulder index of the American Shoulder and Elbow surgeons (ASES). The outpatient follow up time required and the presence of other shoulder injuries, time delay to surgery and the time off work were also recorded. Results. Outcome scores for patients who sustained simple vs comminuted fractures were not significantly different (OS = 41.8 vs 41, ASES 23.8 vs 23.4, UCLA 26.6 vs 26.3). Time taken off work was less in those who had a comminuted vs a simple fracture (21 vs 30 weeks). Shoulder dislocation was present in 77% and patients had a significantly worse outcome than those with no dislocation (OS = 40.6 vs 44, ASES 22.9 vs 26). Rotator cuff repair was required in 21% of patients and was also associated with a worse outcome (OS 42.8 vs 36.8, ASES 24.5 vs 20.5). Post fixation displacement of the GT fracture of < 5 mm led to a significantly better outcome than displacement >5mm (OS = 43 vs 37, ASES = 25.6 vs 17.7, UCLA 28.2 vs 21.3). Conclusion. Isolated fractures of the greater tuberosity have a worse outcome if they are associated with shoulder dislocation, rotator cuff tear and post fixation displacement of >5mm