Citations

Background The stabilizing role of the deltoid muscle has not been extensively studied. Purpose To study the contribution of the deltoid muscle to anterior stability of the shoulder. Study Design Controlled laboratory study. Methods We used nine fresh cadaveric shoulders with the arm at 90° of abduction and 90° of external rotation. The position of the humeral head was monitored by an electromagnetic tracking device with 0 and 1.5 kg of anterior translation force; with 0, 1, 3, and 5 kg of force applied to each of the anterior, middle, and posterior portions of the deltoid muscle; and with the capsule intact, vented, and with a simulated Bankart lesion. Results With the capsule intact, anterior displacement was significantly reduced by application of load to the middle deltoid muscle. After the capsule was vented, load application to the anterior, middle, or posterior deltoid muscle significantly reduced anterior displacement. With a simulated Bankart lesion, effects of muscle loading were most apparent: anterior displacement was significantly reduced with loading of each muscle portion. Conclusion The deltoid muscle is an anterior stabilizer of the glenohumeral joint with the arm in abduction and external rotation. Clinical Relevance The stabilizing function of the deltoid muscle takes on more importance as the shoulder becomes unstable.

Normative data are useful for assessing isometric shoulder strength in patients with bilateral shoulder abnormalities. The purpose of this study was to develop a normative database for shoulder strength in the clinically relevant positions and movements. Twenty combinations of exertions and postures—including flexion, extension, abduction, adduction, internal rotation, and external rotation—were tested for both the dominant and nondominant sides. Strength was measured isometrically using a modified Cybex II dynamometer. The cross-sectional study design included 120 subjects (60 women and 60 men) ranging in age from 20 to 78 years from southern Minnesota. Tables of normative strength data were constructed. Multivariate analyses were performed to assess the effect of age, sex, and weight on strength. Age was negatively associated with all strength measures, and weight was positively associated with them. Men were stronger than women when controlling for age and weight. Statistically significant differences between dominant and nondominant shoulders were found for only some of the strength measures taken. These normal data will be useful to the clinician, as they permit a standard against which to compare shoulder strength.

Background An anteroinferior osseous defect of the glenoid rim is sometimes encountered in patients with recurrent anterior dislocations of the shoulder. A defect of more than 21% of the glenoid length is reported to cause instability after Bankart repair. Hypothesis We can estimate the critical size of glenoid defects by using radiography or computed tomography. Study Design A controlled laboratory study. Methods Osseous defects of 0%, 9%, 21%, 34%, and 46% of the glenoid length were created stepwise in 12 cadaveric scapulae, and plain radiographs simulating the axillary and West Point views and computed tomographic images were obtained. The maximum width of the remnant glenoid was measured under each condition and expressed as a percentage of the width of the intact glenoid. Results A 21% defect appeared to be 18.6% of the intact glenoid on the West Point view. With computed tomography, a 21% defect resulted in loss of 50% of the width on a single slice across the lower one-fourth of the glenoid. Conclusions We can estimate the size of a glenoid defect by using the West Point radiographic view or computed tomogram. Clinical Relevance These images gave decisive information as to whether an osseous glenoid defect required bone grafting to achieve stability after Bankart repair.

AbstractIntroductionDepression and neuropsychiatric disorders in individuals with essential tremor (ET) are not well characterized in the literature.MethodsWe compared 104 ET subjects with 481 non‐ET controls involved in the Arizona Study of Aging and Neurodegenerative Disorders. An analysis of baseline depression scales and neuropsychiatric inventory (NPI) was done between the two groups. Additionally, comparisons were made within the ET group based on tremor severity, duration of tremor, and age of onset.ResultsThere were no significant differences between the ET and non‐ET groups. There were no significant differences in the ET group above and below the median tremor duration. Additionally, no differences were found in the ET group based on objective measures of tremor severity, age of onset, or those with subjectively distressing tremor compared with those without.ConclusionThere were no significant differences in depressive symptoms between ET and non‐ET groups. Furthermore, no correlation was found between depressive symptoms in ET groups based on tremor severity, duration, or age of onset.

AbstractSubstance P (SP), a neurotransmitter released after injury, has been linked to deregulated tissue repair and fibrosis in musculoskeletal tissues and other organs. Although SP inhibition is an effective treatment for nausea, it has not been previously considered as an anti‐fibrotic therapy. Although there are extensive medical records of individuals who have used SP antagonists, our analysis of human registry data revealed that patients receiving these antagonists and arthroplasty are exceedingly rare, thus precluding a clinical evaluation of their potential effects in the context of arthrofibrosis. Therefore, we pursued in vivo studies to assess the effect of SP inhibition early after injury on pro‐fibrotic gene expression and contractures in an animal model of post‐traumatic joint stiffening. Skeletally mature rabbits (n = 24) underwent surgically induced severe joint contracture, while injected with either fosaprepitant (a selective SP antagonist) or saline (control) early after surgery (3, 6, 12, and 24 h). Biomechanical testing revealed that differences in mean contracture angles between the groups were not statistically significant (P = 0.27), suggesting that the drug neither mitigates nor exacerbates joint contracture. However, microarray gene expression analysis revealed that mRNA levels for proteins related to cell signaling, pro‐angiogenic, pro‐inflammatory, and collagen matrix production were significantly different between control and fosaprepitant treated rabbits (P < 0.05). Hence, our study demonstrates that inhibition of SP alters expression of pro‐fibrotic genes in vivo. This finding will motivate future studies to optimize interventions that target SP to reduce the formation of post‐traumatic joint contractures.

Introduction: This study set out to clarify the differential acute cognitive impact of lorazepam based on varying genetic risk for Alzheimer disease. Methods: Fifty-seven cognitively unimpaired individuals aged 51 to 88, genotyped according to apolipoprotein E (APOE) and translocase of outer mitochondrial membrane (40 homolog) poly-T lengths, completed cognitive testing before, 2.5 and 5 hours after receiving a 1 mg dose of lorazepam. Results: Post-lorazepam, there were significant (P<0.05) declines from baseline in memory, psychomotor processing speed, and executive function. At 2.5 hours, the magnitude of this lorazepam-induced cognitive change was significantly greater in the APOE3/4 group than in the APOE3/3 group for tests of working memory and visuospatial memory/executive function. At 5 hours postchallenge, verbal memory and working memory deficits persisted in the APOE3/4 group compared with the APOE3/3 group. At 5 hours after lorazepam challenge, as compared with the very long/very long group, the short/short group performed slightly worse on a test of working memory (P<0.05), but no other differences were observed among translocase of the outer mitochondrial membrane 40 homolog poly-T variant groups. Discussion: The lorazepam challenge may be unmasking presymptomatic cognitive dysfunction associated with APOE4 carriage.

ABSTRACTIntroduction: Rotator cuff (RC) tears result in muscle atrophy and fat infiltration within the RC muscles. An estimation of muscle quality and deformation, or extensibility, is useful in selecting the most appropriate surgical procedure. We determined if noninvasive quantitative assessment of intramuscular fat using MRI could be used to predict extensibility of the supraspinatus muscle. Methods: Seventeen cadaveric shoulders were imaged to assess intramuscular fat infiltration. Extensibility and histological evaluations were then performed. Results: Quantitative fat infiltration positively correlated with histological findings and presented a positive correlation with muscle extensibility (r = 0.69; P = 0.002). Extensibility was not significantly different between shoulders graded with a higher fat content versus those with low fat when implementing qualitative methods. Discussion: A noninvasive prediction of whole‐muscle extensibility may directly guide pre‐operative planning to determine if the torn edge could efficiently cover the original footprint while aiding in postoperative evaluation of RC repair. Muscle Nerve 57: 129–135, 2018