Lateralized Center of Rotation and Lower Neck-Shaft Angle Are Associated With Lower Rates of Scapular Notching and Heterotopic Ossification and Improved Pain for Reverse Shoulder Arthroplasty at 1 Year.

Heterotopic ossification and scapular notching are common following reverse total shoulder arthroplasty. Compared with the original Grammont-style prosthesis with a medialized center of rotation (COR) and a 155° neck-shaft angle, lateralization of COR and reduction of neck-shaft angle have been associated with decreased incidence of scapular notching. The authors hypothesized that these design features may also be effective in reducing heterotopic ossification after reverse total shoulder arthroplasty. Ninety-seven consecutive patients who underwent reverse total shoulder arthroplasty performed by a single surgeon were included in the study. Forty-eight patients received a Grammont-style prosthesis, and 49 received a prosthesis with either 6 mm or 10 mm of lateral COR offset and a 135° neck-shaft angle. Radiographs at 1-year follow-up were reviewed by 2 surgeons for notching and heterotopic ossification. Patient-reported outcome scores and range of motion were also compared between the groups. More patients in the Grammont-style group showed scapular notching (Grammont, 35.4%; lateral COR, 12.2%; P=.018) and heterotopic ossification (Grammont, 47.9%; lateral COR, 22.4%; P=.009). The lateralized COR group reported lower pain on the visual analog scale (Grammont mean, 1.1; lateral COR mean, 0.5; P=.01) and trended toward better American Shoulder and Elbow Surgeons scores (Grammont mean, 77.2; lateral COR mean, 83.4; P=.05). However, range of motion was similar between the 2 groups. Compared with the Grammont-style prosthesis, the lateralized COR prosthesis with a decreased neck-shaft angle resulted in a lower incidence of both scapular notching and heterotopic ossification as well as better pain scores and a trend toward improved function at 1 year after reverse total shoulder arthroplasty. [Orthopedics. 2018; 41(4):230-236.].

Computed tomography underestimates rotator cuff pathology in patients with glenohumeral osteoarthritis.

BACKGROUND: Computed tomography (CT) is the standard assessment of glenoid morphology before shoulder arthroplasty and is commonly used to evaluate rotator cuff pathology in patients with glenohumeral osteoarthritis (GHOA). Magnetic resonance imaging (MRI) is not routinely used in this setting but has higher sensitivity in diagnosing full-thickness rotator cuff tears (RCT) and is considered the gold standard. The purpose of this study was to determine the sensitivity and specificity of CT in diagnosing full-thickness RCTs and compare the evaluation of fatty infiltration and muscle atrophy on CT vs. MRI in the setting of GHOA. METHODS: In this retrospective case-controlled study, we identified 49 patients from a prospectively maintained 2-surgeon registry who received preoperative CT and MRI scans for the evaluation of GHOA between 2011 and 2016. Three fellowship-trained shoulder surgeons assessed rotator cuff integrity, fatty infiltration, and muscle atrophy in the CT and MRI scans. RESULTS: CT sensitivity and specificity were 20% and 95.5%, respectively. Fatty infiltration was significantly lower on CT for the supraspinatus (P = .003), infraspinatus (P < .001), and subscapularis (P = .0182), whereas muscle atrophy was significantly lower on CT for only the supraspinatus (P = .0023). CONCLUSIONS: Our results suggest that CT underestimates the frequency of full-thickness RCTs and the severity of fatty infiltration and muscle atrophy in the setting of GHOA before total shoulder arthroplasty.

Critical shoulder angle is associated with full-thickness rotator cuff tears in patients with glenohumeral osteoarthritis.

BACKGROUND: Higher critical shoulder angle (CSA) is correlated with rotator cuff tears (RCTs), whereas lower CSA is associated with glenohumeral osteoarthritis (OA). Our goal was to investigate whether patients with concurrent glenohumeral OA and full-thickness RCTs demonstrate a higher CSA than patients with OA alone. METHODS: Using a 2-surgeon shoulder arthroplasty registry, we identified 31 patients with glenohumeral OA and full-thickness RCTs confirmed by plain radiography and magnetic resonance imaging, respectively. Sixty-two age- and gender-matched controls (1:2 ratio) with glenohumeral OA and an intact rotator cuff were identified from the same registry. Two independent observers evaluated the radiographs for CSA and acromiohumeral index. RESULTS: The average CSA was 30° in the OA control group and 35° in the concurrent RCT and OA group (P < .0001). Acromiohumeral index was comparable between the groups (P = .13). Interobserver reliability of the independent reviewers was excellent (κ = 0.89; Ρ = 0.95). The receiver operating characteristic curve for CSA demonstrated that a value >35° was 90% specific and 52% sensitive for a full-thickness RCT in the setting of OA (area under curve = 0.84). CONCLUSION: Concurrent glenohumeral OA and full-thickness RCT are associated with greater CSA values compared with patients with glenohumeral OA alone. The CSA measurement may be useful in determining the need for magnetic resonance imaging to assess rotator cuff integrity in the arthritic population.