Reverse total shoulder arthroplasty (RTSA) has become instrumental in relieving pain and returning function to patients with end-stage rotator cuff disease. A distalized and medialized center of rotation in addition to a semi-constrained implant design allows the deltoid to substitute for the non-functioning rotator cuff. The purpose of this study was to examine the relationship between specific deltoid and rotator cuff muscle parameters and functional outcomes following RTSA. Patients undergoing RTSA by a single surgeon were enrolled in a prospective, IRB approved RTSA outcomes registry. Inclusion criteria were diagnosis of cuff tear arthropathy or massive rotator cuff tear, a minimum 2-year follow-up, and a preoperative shoulder MRI. We excluded patients undergoing revision arthroplasty, fracture, and a history of previous open shoulder surgery. For the 28 patients meeting our criteria, the cross-sectional area (CSA) of the anterior, middle, and posterior deltoid were measured on an axial MRI (Figure 1). Fatty infiltration (FI) of the deltoid, supraspinatus (SS), infraspinatus (IS), teres minor, and subscapularis were assessed on sagittal T1-MRI quantitatively via image processing and qualitatively on the 5-point Fuchs scale by a fellowship-trained musculoskeletal radiologist. Outcome measures included active forward elevation (aFE), active external rotation (aER), active internal rotation (aIR), strength in abduction, Constant-Murley score (CMS), Subjective Shoulder Value (SSV), Visual Analogue Scale (VAS) pain, and American Shoulder and Elbow Surgeons (ASES) total and ASES activities of daily living (ADL) scores as assessed by a trained, clinical research nurse. Correlation of deltoid CSA and FI with outcomes measures was analyzed with a Spearman rank correlation coefficient (ρ) with significance at Introduction:
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Studies have demonstrated both clinical and radiological success of reverse shoulder arthroplasty (RTSA), with follow-up approaching 10-years. To date, most RTSA studies involve cemented fixation of the humeral components, and most involving uncemented RTSAs have used implants not necessarily designed for bony ingrowth. Cementless fixation utilizing proximally porous-coated (PPC) femoral implants has shown long term survivorship approaching 99% at greater than 10-years follow-up in total hip arthroplasty. Currently, the number of commercially available PPC RTSA implants is steadily growing, but there has been no published study examining clinical and radiographic outcomes in PPC, press-fit humeral stems. We hypothesized that the clinical and radiographic results of uncemented RTSA utilizing a PPC humeral stem would be similar to cemented RTSA stems when followed for at least 2-years. A prospective, IRB approved RTSA outcomes registry with 261 patients that underwent RTSA by one fellowship-trained orthopaedic surgeon between 2005 and 2008 was reviewed. Inclusion criteria were diagnosis of cuff tear arthropathy or severe rotator cuff deficiency refractory to all other treatments, and minimum 2-year clinical and radiographic follow-up. Exclusion criteria were proximal humeral fractures, glenohumeral instability, rheumatoid arthritis, incomplete follow-up, and revision arthroplasty. Outcome measures included active forward elevation (aFE), active external rotation (aER), active internal rotation (aIR), Constant-Murley score (CS), Subjective Shoulder Value (SSV), visual analogue scale (VAS) pain, and American Shoulder and Elbow Surgeons (ASES) score. Radiographs at 2 weeks, 3 months, 1 year, 2 years and yearly thereafter were evaluated for humeral component position, osteolysis, humeral component radiolucent lines (RLLs), stress shielding, and scapular notching. Statistical analysis was conducted by an independent institutional statistician.Introduction:
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