The Association between Radiologic Severity of Rotator Cuff Pathology and Supraspinatus Weakness on Biomechanical Assessment (229)

Objectives: Many different magnetic resonance imaging (MRI)-based classifications are used to characterize rotator cuff supraspinatus pathology, ranging from mild tendinopathy to full-thickness tears. While MRIs are chiefly utilized to guide the need for and approach to operative management of supraspinatus pathology, the functional implications, if any, across the entire range of pathologies have not been defined. The purpose of this biomechanical study was to examine shoulder strength and function in patients presenting with presumptive supraspinatus pathology and to determine if these clinical parameters are correlated with radiologic severity. Methods: We prospectively enrolled 171 patients with suspected rotator cuff pathology disease and without apparent strength deficit on traditional rotator cuff physical examination (PE). Exclusion criteria were radiographically apparent glenohumeral OA, previously diagnosed rotator cuff tear of the affected shoulder, previously diagnosed adhesive capsulitis, prior ipsilateral shoulder surgery, injury to the ipsilateral hand or wrist, limited range of motion, and history or radiographic evidence of anterior or posterior shoulder dislocation. For both clinical (e.g. testing isotonic strength in patients with frank weakness yields unreliable strength measurements and provides little useful information) and ethical (e.g. to avoid causing pain to patients already experiencing significant shoulder pain) reasons, this study evaluating dynamic strength testing was strictly limited to patients with negative traditional, static PE tests. All patients underwent two bilateral shoulder strength tests using dynamometry; first, isometric strength was measured at 90 degrees of abduction and, second, isotonic strength was measured eccentrically from full abduction throughout the full range of motion until the arm was at the patient’s side. For both of these tests, the examiner placed the handheld dynamometer (Hoggan microFET® 3; Hoggan Scientific, LLC, Salt Lake City UT, USA) on the patient’s wrist, perpendicular to the arm, to measure the force applied along the arc. Absolute strength and symptomatic-to-asymptomatic arm (S/A) strength ratios were calculated. All patients were included in analyses of absolute strength measurements on strength testing; patients who had a history or clinical evidence of contralateral shoulder pathology were excluded from analyses of S/A strength ratios. Patients then underwent shoulder MRI, classifying supraspinatus findings into one of seven ordinal categories. The primary outcome was the relationship between the radiologic severity of supraspinatus pathology on MRI and the degree of rotator cuff strength deficit upon exam. Results were analyzed for both isotonic and isometric function. Results: The study cohort consisted of 171 patients (102 [59.6%] males, 69 [40.4%] females). The mean patient age (± 95% CI) was 52.0 ± 1.9 years. The mean symptom duration (± 95% CI) was 10.8 ± 2.9 months. MRI revealed: 26 (15.2%) instances of no supraspinatus pathology, 37 (21.6%) instances of tendinopathy, 17 (9.9%) instances of supraspinatus fraying, 39 (22.8%) partial thickness tears (PTTs), 13 (7.6%) high-grade PTTs, 12 (7.0%) focal full thickness tears (FTTs)/full-thickness perforations, and 27 (15.8%) FTTs. Isotonic strength : Increasing imaging severity was significantly associated with decreasing absolute strength during isotonic testing ( P=0.036, Table 1). Specifically, absolute strength measurements declined with increasingly severe imaging findings, from no tear [59.9 N], to tendinopathy [50.9 N], to fraying [48.2 N], to PTT [55.0 N], to high-grade PTT [48.9 N], to focal FTT/full thickness perforation [45.7 N], to FTT [44.2 N]. Similarly, increasing imaging severity was significantly associated with decreasing S/A strength ratios during isotonic testing ( P=0.022, Table 1). Isotonic S/A strength ratios declined with increasingly severe imaging findings, from no tear [91.9%], to tendinopathy [70.8%], to fraying [66.1%], to PTT [76.2%], to high-grade PTT [75.7%], to focal FTT/full thickness perforation [65.2%], to FTT [63.3%]. Isometric strength : In contrast to isotonic testing, increasing imaging severity was not significantly associated with decreased absolute strength measurements on isometric testing ( P=0.12, Table 2). Similar results were seen for isometric S/A ratio, as increasing imaging severity was not significantly associated with S/A strength ratio ( P=0.085, Table 2). Conclusions: Radiologic severity of supraspinatus pathology was correlated with dynamic clinical function across the full range of pathology, revealing the functional importance of these frequently-used classifications. The lower discriminatory ability of isometric measurements and higher strength measurements on isometric assessment may be related to a greater role of compensatory musculature in static testing. These biomechanical results support the need for future work investigating the utility of dynamic rotator cuff physical examination maneuvers.

River Jets Versus Wave-Driven Longshore Currents at River Mouths

At river mouths, fluvial jets and longshore currents (LSCs) generated by waves interact hydrodynamically. This idealized numerical modeling study simulates a large number of hydro-morphodynamic conditions (650) to explore the emergent hydrodynamics determined by different mouth bar volumes and geometries, river discharge, wave heights, and directions and their potential stress on river-mouth development. We find that in the absence of a river-mouth bar (RMB), interactions are driven by momentum balances, expressed either as the balance of wave momentum flux (Mw) and jet momentum flux (Mj), or the balance of river jet discharge (QJet) and longshore current discharge (QLSC). When a RMB is present, the topography modifies the structure of the jet by spreading it, and we quantify this mechanism through the lateral jet transfer rate (LJT). Secondly, topography generates complex longshore wave-driven circulation as a result of the protruding shoreface which serves as a platform on which counter LSCs develop. The balance in QJet/QLSC may be used as an indication of the type of circulation. High and oblique waves favor longshore circulation and RMB bypass, whereas low waves and normal-to-coast angles generate diverging LSCs on the mouth bar crest which interrupts the longshore circulation. A quantification of the dynamic diversion is proposed in the form of the non-dimensional Dynamic diversion index (DyD), which scales with the product of Mj and Mw, and can account for the absolute strength of hydrodynamic interactions occurring at river mouths. RMB morphology can affect DyD in multiple ways by strengthening or by weakening the interactions. The DyD effect seems to increase with increasing RMB size, indicating that the RMB scale regulates the interplay of the wave-driven circulation and the river jet which further controls the adjacent topography changes.

Pooled sputum to optimise the efficiency and utility of rapid, point-of-care molecular SARS-CoV-2 testing

Background As SARS-CoV-2 testing expands, particularly to widespread asymptomatic testing, high sensitivity point-of-care PCR platforms may optimise potential benefits from pooling multiple patients’ samples. Method We tested patients and asymptomatic citizens for SARS-CoV-2, exploring the efficiency and utility of CovidNudge (i) for detection in individuals’ sputum (compared to nasopharyngeal swabs), (ii) for detection in pooled sputum samples, and (iii) by modelling roll out scenarios for pooled sputum testing. Results Across 295 paired samples, we find no difference (p = 0.1236) in signal strength for sputum (mean amplified replicates (MAR) 25.2, standard deviation (SD) 14.2, range 0–60) compared to nasopharyngeal swabs (MAR 27.8, SD 12.4, range 6–56). At 10-sample pool size we find some drop in absolute strength of signal (individual sputum MAR 42.1, SD 11.8, range 13–60 vs. pooled sputum MAR 25.3, SD 14.6, range 1–54; p < 0.0001), but only marginal drop in sensitivity (51/53,96%). We determine a limit of detection of 250 copies/ml for an individual test, rising only four-fold to 1000copies/ml for a 10-sample pool. We find optimal pooled testing efficiency to be a 12–3-1-sample model, yet as prevalence increases, pool size should decrease; at 5% prevalence to maintain a 75% probability of negative first test, 5-sample pools are optimal. Conclusion We describe for the first time the use of sequentially dipped sputum samples for rapid pooled point of care SARS-CoV-2 PCR testing. The potential to screen asymptomatic cohorts rapidly, at the point-of-care, with PCR, offers the potential to quickly identify and isolate positive individuals within a population “bubble”.

Morphology of the Patellar Tendon and the Contractility Response of the Quadriceps: Symmetry and Gender Analysis

The purpose of the study was to describe the differences between the dominant and non-dominant leg regarding contractility response and quadriceps strength and the morphology and stiffness of the patellar tendon (PT) in a group of physically active men and women. Fifty physically active subjects (36 men and 14 women) were evaluated for morphology and stiffness of the PT, contractility response of the rectus femoris of the quadriceps, isometric strength of the quadriceps and hamstrings, and isokinetic strength (concentric and eccentric) at 60°/s of the knee extensors. The measurements were made on the subject’s dominant and non-dominant leg. The men showed a greater thickness of the PT in both legs compared to the women. Regarding the contractility response, the women recorded a 10.1 ± 16.2% (p = 0.038) greater contraction time (ct) in the dominant versus the non-dominant leg and the men recorded 11.9% (p = 0.040) higher values in the dominant leg compared to the women. In all the absolute strength measurements the men recorded higher values (p < 0.05) than the women, however, when the values were normalised with respect to the muscle mass of the leg these differences disappeared. The dominant leg showed values of isometric strength and eccentric strength at 60°/s (p < 0.05) greater than the non-dominant leg. The reference values provided in this study of the knee extensors and PT may be useful for detecting possible muscular or tendinous anomalies.

Anthropometric and physical performance of amateur rugby players within specific playing positions

BACKGROUND: This study examined the differences in physical and anthropometric traits between specific playing positions (i.e., forwards: front row, second row, back row; backs: half backs, centers, wings/fullbacks) in amateur rugby players and analyzed the magnitude of correlations among jump, sprint, and strength measures in forwards and backs. METHOD: Sixty-four male rugby players were assessed in anthropometrics, a variety of vertical jumps, 10- and 30-m sprint, and strength tests (i.e., squat and bench press). RESULTS: Front row forwards (FFR) demonstrated significantly higher body mass (BM) than second row (FSR) and back row (FBR) (107.4 ± 12.8, 99.1 ± 9.9 and 91.6 ± 7.6 kg respectively; p< 0.001). FFR showed greater absolute strength in bench press and squat, although no differences were found in relative strength. Regarding the differences in jump performance, FBR and FSR showed significantly (p< 0.05) and significant to non-significant (p= 0.042–0.078, ES = 0.90–1.55) higher jumps in all tasks compared to FFR. Moreover, FBR demonstrated lower sprint times and greater maximum sprinting speed (MSS) than FFR (p< 0.01). For the backs, centers (BCEN) were significantly heavier (p< 0.05) and exhibited a non-significantly moderate larger sprint momentum (p= 0.068, ES = 0.75) compared to half backs (BHB). MSS values were small to moderately greater in favor of wings/fullbacks [BWFB] (p= 0.188–0.059, ES = 0.50–0.71). Finally, statistically significant correlations were found between drop jump (flight time) and jump height across all jump tasks, sprint times and speed for both forwards (r= 0.541 to 0.996, p< 0.001) and backs (r= 0.422 to 0.995, p< 0.05). CONCLUSIONS: In conclusion, Front row forwards demonstrated significant, small to very large differences, when compared to their specific peers, whereas the backs were more similar. Additionally, our results indicated moderate to strong associations between explosive tasks such as sprinting and jumping in both playing positions.

Preparation of High Strength Plywood from Partially Delignified Densified Wood

Wood and natural fibers exhibit an advantageous combination of good mechanics at comparably low density. Nevertheless, comparing absolute strength and stiffness, wood is clearly inferior to materials such as metals and engineered composites. Since there is a strong correlation between wood density and wood mechanical performance, densification by transversal compression suggests itself as a route towards improved mechanics. Partially delignified densified spruce veneers with excellent tensile properties were produced by means of an alkaline (AL) and an organosolv (OS) approach. Plywood specimens were manufactured using treated veneers glued with a phenol-resorcinol-formaldehyde adhesive and were compared with plywood samples made of native spruce veneers (Ref) and spruce veneer densified after plasticization by water impregnation (H2O). Roughly, the bending strength and the modulus of elasticity of plywood from partially delignified densified wood were improved by a factor of 2.4 and 3.5, respectively. Interlaminar shear strength did not match this improvement after partial delignification. Together with excessive thickness swelling, this might be a drawback of partially delignified densified wood in need for further research.

Differences of Relative and Absolute Strength of Individuals With Spinal Cord Injury From Able-Bodied Subjects: A Discriminant Analysis

Context:Strength training is one of the most common interventions employed to increase functional independence during rehabilitation of individuals with spinal cord injury (SCI). However, in the literature, different results have been reported in terms of strength modifications after a SCI compared with a control group (CG).Objective:This study aimed to verify whether discriminant analysis using relative and absolute strength is able to discriminate individuals with different levels of SCI from a CG and to compare strength values of men with different levels of SCI with a CG.Design:Cross-sectional study.Setting:Rehabilitation hospital setting.Participants:A total of 36 individuals with SCI stratified in tetraplegia (TP; C6–C8), high paraplegia (HP; T1–T6), and low paraplegia (LP; T7–L2), and 12 matched control subjects were enrolled in the study.Main Outcome Measures:The subjects performed a maximum strength test of elbow extension/flexion and also shoulder abduction/adduction and flexion/extension in an isokinetic dynamometer. Discriminant analysis was carried out to identify which strength variables would be able to discriminate the TP, HP, or LP groups from the CG. A 1-way analysis of variance was performed to compare peak torque and agonist/antagonist ratio means.Results:Shoulder adduction, followed by elbow extension peak torque, was the best variable for discriminating the TP group from the CG (function coefficients: −0.056 and 0.051, respectively, Wilks Λ = 0.41,P ≤ .05). There were no significant differences between the HP group, LP group, and CG.Conclusions:The strength similarity of the paraplegic groups and the CG should not be extrapolated for activities of daily living or sports. The TP group demonstrated lower peak torque for all movements than the CG.

A Not-So-Special Relationship America and Britain

The Brexiteers presented a revived partnership with the United States as the cornerstone of Britain’s new Anglosphere-centered diplomacy. Without the United States, any Anglosphere project would lose meaning, and the future of Britain outside the European Union would be grim. But this chapter argues that the focus on the “special relationship” was based on a delusional national myth. Historically, the specialness, which discounted an enormous gap in terms of power and influence between the two countries, has been more keenly felt in London than in Washington. Since 1945, America’s absolute strength and Britain’s relative weakness has always determined a highly unbalanced relationship. In the eyes of Dean Acheson—Secretary of State in the Truman Administration—British rhetoric surrounding the “special” connection between the two countries reflected nothing more than the UK’s unwillingness to accept its post-imperial status: that of a simple transatlantic intermediary and Anglo-Saxon balancer in European affairs. It has been observed that, from 1945 onwards, the “special relationship” rapidly assumed the character of a “special dependancy”, with Britain being very much the junior partner. Currently, the difference in terms of power and influence between the two countries is as great as in the past—if not even greater, given Britain’s diminished influence in European affairs. On top of that, bridging the policy inconsistencies between “America First” (based on unilateralism and protectionism) and “Global Britain” (based on multilateralism and free markets) might represent an insurmountable obstacle.