Prevention strategies and modifiable risk factors for sport-related concussions and head impacts: a systematic review and meta-analysis.

OBJECTIVES: To evaluate prevention strategies, their unintended consequences and modifiable risk factors for sport-related concussion (SRC) and/or head impact risk. DESIGN: This systematic review and meta-analysis was registered on PROSPERO (CRD42019152982) and conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. DATA SOURCES: Eight databases (MEDLINE, CINAHL, APA PsycINFO, Cochrane (Systematic Review and Controlled Trails Registry), SPORTDiscus, EMBASE, ERIC0 were searched in October 2019 and updated in March 2022, and references searched from any identified systematic review. ELIGIBILITY CRITERIA: Study inclusion criteria were as follows: (1) original data human research studies, (2) investigated SRC or head impacts, (3) evaluated an SRC prevention intervention, unintended consequence or modifiable risk factor, (4) participants competing in any sport, (5) analytic study design, (6) systematic reviews and meta-analyses were included to identify original data manuscripts in reference search and (7) peer-reviewed. Exclusion criteria were as follows: (1) review articles, pre-experimental, ecological, case series or case studies and (2) not written in English. RESULTS: In total, 220 studies were eligible for inclusion and 192 studies were included in the results based on methodological criteria as assessed through the Scottish Intercollegiate Guidelines Network high ('++') or acceptable ('+') quality. Evidence was available examining protective gear (eg, helmets, headgear, mouthguards) (n=39), policy and rule changes (n=38), training strategies (n=34), SRC management strategies (n=12), unintended consequences (n=5) and modifiable risk factors (n=64). Meta-analyses demonstrated a protective effect of mouthguards in collision sports (incidence rate ratio, IRR 0.74; 95% CI 0.64 to 0.89). Policy disallowing bodychecking in child and adolescent ice hockey was associated with a 58% lower concussion rate compared with bodychecking leagues (IRR 0.42; 95% CI 0.33 to 0.53), and evidence supports no unintended injury consequences of policy disallowing bodychecking. In American football, strategies limiting contact in practices were associated with a 64% lower practice-related concussion rate (IRR 0.36; 95% CI 0.16 to 0.80). Some evidence also supports up to 60% lower concussion rates with implementation of a neuromuscular training warm-up programme in rugby. More research examining potentially modifiable risk factors (eg, neck strength, optimal tackle technique) are needed to inform concussion prevention strategies. CONCLUSIONS: Policy and rule modifications, personal protective equipment, and neuromuscular training strategies may help to prevent SRC. PROSPERO REGISTRATION NUMBER: CRD42019152982.

Point of impact: the effect of size and speed on puncture mechanics.

The use of high-speed puncture mechanics for prey capture has been documented across a wide range of organisms, including vertebrates, arthropods, molluscs and cnidarians. These examples span four phyla and seven orders of magnitude difference in size. The commonality of these puncture systems offers an opportunity to explore how organisms at different scales and with different materials, morphologies and kinematics perform the same basic function. However, there is currently no framework for combining kinematic performance with cutting mechanics in biological puncture systems. Our aim here is to establish this framework by examining the effects of size and velocity in a series of controlled ballistic puncture experiments. Arrows of identical shape but varying in mass and speed were shot into cubes of ballistic gelatine. Results from high-speed videography show that projectile velocity can alter how the target gel responds to cutting. Mixed models comparing kinematic variables and puncture patterns indicate that the kinetic energy of a projectile is a better predictor of penetration than either momentum or velocity. These results form a foundation for studying the effects of impact on biological puncture, opening the door for future work to explore the influence of morphology and material organization on high-speed cutting dynamics.

[Validity of ultrasound examinations of disorders of the shoulder joint]. / Validität der sonographischen Untersuchung des Schultergelenkes--Prospektive, randomisierte und doppelt blinde, arthroskopisch kontrollierte Studie an 239 Fällen.

OBJECTIVES: The objective of the present study was to assess the validity of ultrasound diagnosis of shoulder disorders in relation to examiner experience. METHODS: A total of 239 patients referred to us for shoulder arthroscopy from October 2001 to June 2004 were prospectively studied by ultrasound. The following ultrasound diagnoses were evaluated: total and partial rotator cuff tears, calcific tendinitis, biceps tendon injuries and subacromial bursitis. Examiner A established the ultrasound diagnoses and examiner B performed the surgery during week A, whereas examiner B did the examinations and examiner A operated in week B. The surgeon was blinded to the ultrasound results. Examiner A conducts ultrasound training seminars for DEGUM, the German Society of Ultrasound in Medicine, and has performed over 10,000 ultrasound examinations, with an average of roughly 150 examinations per year. Examiner B completed his ultrasound training some years ago and has performed roughly 1500 examinations (50 per year). The results were analysed in a time-independent and blinded manner by the co-author (H), who neither operated nor examined the patients. RESULTS: Ultrasound correctly identified 103 of 104 complete rotator cuff tears (sensitivity: 0.99--specificity: 0.99--accuracy: 98.7%). Both examiners achieved comparable results. Moreover, 41 of 52 partial rotator cuff tears were detected preoperatively (sensitivity: 0.79--specificity: 0.91--accuracy: 88.7%). Examiner A achieved a sensitivity of 0.92, a specificity of 0.95, and an accuracy of 94.7%. The corresponding rates for examiner B were: sensitivity 0.68, specificity 0.86, and accuracy 81.3%. 16 of 23 injuries of the long biceps tendon were identified correctly (4 of 8 dislocations and 12 of 15 tears: sensitivity 0.53; specificity 0.9; accuracy 95.3%). Examiner A achieved: sensitivity 0.58; specificity 0.99; accuracy 91.7% compared to examiner B: sensitivity 0.33; specificity 0.97; accuracy 95.3%. Both examiners correctly identified all 32 cases of calcific tendinitis (sensitivity 1.0; specificity 0.98; accuracy 98.3 % examiner A: 1.0--1.0--100% examiner B: 1.0--0.96--96.2%). 22 of 28 cases of subacromial bursitis were correctly diagnosed (sensitivity 0.79; specificity 0.98; accuracy 95.8% examiner A: 0.92--0.99--98.5% examiner B: 0.69--0.97--92.5%). CONCLUSIONS: Preoperative ultrasound examination of the shoulder permits a reliable diagnosis of complete rotator cuff tears and calcium deposits (calcific tendinitis). The method is less sensitive but sufficiently reliable for the diagnosis of partial rotator cuff tears and pathology of the long biceps tendon. Examiner experience plays an important role in these special cases. Permanent continuous training in the field of ultrasound diagnosis is a prerequisite for sufficient reliability of ultrasound diagnosis of shoulder disorders.

Use of dextran and post-primary antibody fixation in immunoperoxidase staining of fresh frozen tissue. Detection of immunoglobulin associated with squamous carcinomas of the head and neck.

Use of unfixed fresh frozen tissue sections for immunocytochemical studies reduces the possibility of denaturation of antigenic determinants compared to formalin fixation and paraffin embedding procedures. However, tissue and cellular morphology can be extensively altered in the numerous application and washing steps with frozen tissue sections. We tested a number of buffer solutions and showed that the use of dextran-containing buffers and fixation by glutaraldehyde after primary antibody application preserves tissue morphology. The procedures described here are also applicable to ascertaining the presence of Fc receptors of leukocytes in sections of carcinoma tissues. The buffered dextran washes and post-primary antibody fixation method was used to demonstrate the presence of immunoglobulin associated with squamous carcinoma cells. The immunoglobulin was not removed by washing of tissue sections at 37 degrees C but could be removed by low or high pH buffer washes, suggesting that the immunoglobulin is bound in a specific manner.