RESUMEN
Background: One proposed mechanism of rotator cuff disease is scapular motion impairments contributing to rotator cuff compression and subsequent degeneration. Purpose: To model the effects of scapular angular deviations on rotator cuff tendon proximity for subacromial and internal mechanical impingement risk during scapular plane abduction. Study Design: Descriptive laboratory study. Methods: Three-dimensional bone models were reconstructed from computed tomography scans obtained from 10 asymptomatic subjects and 9 symptomatic subjects with a clinical presentation of impingement syndrome. Models were rotated to average scapular orientations from a healthy dataset at higher (120°) and lower (subject-specific) humeral elevation angles to investigate internal and subacromial impingement risks, respectively. Incremental deviations in scapular upward/downward rotation, internal/external rotation, and anterior/posterior tilt were imposed on the models to simulate scapular movement impairments. The minimum distance between the rotator cuff insertions and potential impinging structures (eg, glenoid, acromion) was calculated. Two-way mixed-model analyses of variance assessed for effects of scapular deviation and group. Results: At 120° of humerothoracic elevation, minimum distances from the supraspinatus and infraspinatus insertions to the glenoid increased with ≥5° changes in upward rotation (1.6-9.8 mm, P < .001) or external rotation (0.9-5.0 mm, P≤ .048), or with ≥10° changes in anterior tilt (1.1-3.2 mm, P < .001). At lower angles, ≥20° changes in most scapular orientations significantly increased the distance between the supraspinatus and infraspinatus insertions and the acromion or coracoacromial ligament. Conclusion: A reduction in scapular upward rotation decreases the distance between the rotator cuff tendon insertions and glenoid at 120° humerothoracic elevation. Interpretation is complicated for lower angles because the humeral elevation angle was defined by the minimum distance. Clinical Relevance: These results may assist clinical decision making regarding the effects of scapular movement deviations in patients with rotator cuff pathology and scapular dyskinesia and may help inform the selection of clinical interventions.
RESUMEN
Left ventricular assist devices (LVADs) require anticoagulation therapy with vitamin K antagonists to reduce the risk of thrombotic events. The quality of anticoagulation may be assessed by the time in therapeutic range (TTR). We analyzed a retrospective cohort of LVAD patients at a single institution from January 2012 to September 2014. Primary outcomes included TTR during the study time period and TTR 30 days preceding a bleeding or thrombotic event. Fifty-one patients (mean age 57.0 ± 14.6 years; 78% male) had an overall TTR of 52%. Median international normalized ratio (INR) preceding a bleeding and thrombotic event was 2.7 and 2.2, respectively (p = 0.049). In the 30 days before an event, patients with a bleeding event were more likely to be on low-dose aspirin (37% vs. 12%; p = 0.018) and spend a higher proportion of time above therapeutic range (41% vs. 17%; p = 0.007) compared with those with thrombotic events. The association between a greater percentage of time above therapeutic range in the 30 days before a bleeding event demonstrates the importance of avoiding a supratherapeutic INR in the LVAD patient population and the usefulness of TTR as a measure of the overall quality of anticoagulation and monitoring in an LVAD cohort.
