Faculty Bibliography

Reverse total shoulder arthroplasty (rTSA) implants are intended to restore stability and function to shoulders with rotator cuff deficiency. The implant consists of a glenosphere projecting from a glenoid baseplate and articulating in a socket at the proximal end of a humeral component. Despite the demonstrated clinical efficacy, little information is available regarding the joint forces about this construct and the stability of the glenoid component against these forces. Our hypotheses were that the joint forces about the rTSA were comparable to that about a normal shoulder joint, and that the micromotion between the baseplate and the scapula against these loads would be sufficiently low to induce bone ingrowth. To investigate this, a custom testing rig was constructed to simulate active shoulder elevation in fresh-frozen shoulder specimens. The forces about the rTSA were calculated and found to include compressive and shear forces up to 0.7 and 0.4 BW, respectively. In contrast to a normal shoulder, where the joint forces peak at 90 degrees of abduction, forces about the rTSA were highest at about 60 degrees of abduction. These forces were then applied in cyclic loading conditions to the glenoid baseplate, and the micromotion of the implant relative to the bone was measured in the four quadrants of the component. For two different rTSA designs (DePuy Delta III(R) and Encore RSP(R)) and in the entire range of the fixation testing, the cyclical micromotions were always less than 62 microm. Thus, under loading conditions similar to physiological shoulder elevation, micromotion of the glenoid component was sufficiently low and within previously published limits to induce bone ingrowth

The aim of this study was to identify the magnitude and characteristics of work-related musculoskeletal complaints among perioperative nurses and technicians (PNT) and determine the associated ergonomic risk factors in the operating room (OR) environment based on self-report and focus group discussion. The 50 PNTs who participated in the study completed a self-report survey for musculoskeletal symptoms, Job Description Questionnaire, and Psychometric Evaluation Questionnaire, and participated in focus groups to discuss potential OR ergonomic risk factors. The results of the study demonstrated a high prevalence of work-related musculoskeletal disorders (WMSD) among PNTs, with lower back pain the most prevalent (84%) complaint, followed by ankle/foot (74%) and shoulder (74%) pain. In addition, lower back pain (31%), followed by ankle/knee (24%) pain were found to be the main causes of absenteeism from work. Participants suggested simple ergonomic and engineering solutions can be adopted to improve the work environment of PNTs

Total shoulder arthroplasty is a common treatment for glenohumeral arthritis. One of the most common failure modes of total shoulder arthroplasty is glenoid loosening, causing postoperative pain, limitation of function, and potentially, the need for revision surgery. The literature has devoted considerable attention to the design of the glenoid component; efforts to better understand the biomechanics of the reconstructed glenohumeral joint and identify factors that contribute to glenoid component loosening are ongoing. This article reviews the current state of knowledge about the glenoid in total shoulder arthroplasty, summarizing the anatomic parameters of the intact glenoid, variations in component design and fixation, the mechanisms of glenoid loosening, the outcomes of revision surgery in the treatment of glenoid component failure, and alternative treatments for younger patients

SUMMARY: The purpose of this study was to evaluate the role of reverse shoulder design parameters on performance. A computer analysis was conducted on the Grammont reverse shoulder to quantify the effect of varying design parameters on functional measurements during humeral abduction/adduction. The Grammont reverse shoulder impinged inferiorly and superiorly on the glenoid at 30.75 degrees and 95 degrees of humeral abduction, with an average jump distance of 10 mm. Several linear relationships were identified. To demonstrate the application of these relationships, a novel prosthesis was designed. The proposed 38-, 42-, and 46-mm reverse shoulder designs impinged inferiorly and superiorly on the glenoid at 7.25 degrees /87.5 degrees , 1 degrees /87.5 degrees , and 0 degrees /89.25 degrees of humeral abduction with an average jump distance of 11.7, 13.5, and 14.1 mm, respectively. The results of this study demonstrate that subtle changes in design parameters can minimize inferior glenoid impingement and offer the potential for dramatic functional improvements in range of motion (39%) and jump distance (36%)