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Military Medicine Nov 2018Military personnel are at an increased risk of shoulder injuries due to training and deployment demands, however, there is a lack of information on the tactical...
INTRODUCTION
Military personnel are at an increased risk of shoulder injuries due to training and deployment demands, however, there is a lack of information on the tactical athlete's upper extremity profile. Therefore, the purpose of this study was to examine shoulder musculoskeletal characteristics, including range of motion (ROM), strength, and function, and the relationships between these measures in Marine Corps Forces Special Operations Command (MARSOC) personnel without history of shoulder injury.
MATERIALS AND METHODS
Participants included 195 full-duty male MARSOC personnel (age: 25.38 ± 2.85 yr; height: 1.79 ± 0.06 m, mass: 82.79 ± 7.88 kg) without history of shoulder injury. Measurements of ROM, strength, and function were obtained bilaterally. Shoulder internal rotation (IR) and external rotation (ER) ROM were summed to calculate total arc of motion (ARC). Shoulder IR and ER strength were assessed using an isokinetic dynamometer. Function was evaluated with an explosive push-up.
RESULTS
MARSOC personnel present with significantly increased ER ROM, and decreased IR ROM and ARC in their dominant shoulder. They demonstrated greater IR strength and peak force during the explosive push-up on the dominant side but no bilateral differences in average or peak rate were found. Correlation analyses suggest a weak inverse relationship between strength and ARC (r = -0.15 to -0.24). Positive relationships between strength and function were identified except for dominant IR strength and push-up variables. Those with the greatest ARC demonstrated significantly weaker IR and ER strength compared to those with less motion.
CONCLUSIONS
MARSOC personnel demonstrate shoulder ROM and strength symmetry patterns similar to overhead athletes. Increased dominant shoulder strength does appear to translate to a bilateral functional performance, but overall performance may be limited by the weaker nondominant upper extremity. As ARC increases, IR and ER rotation strength decrease. Repetitive, increased loading of the dominant shoulder during functional movements and training may increase risk of chronic, overuse-type injuries, common to the military. Unilateral exercises and movement analysis should be incorporated to encourage proper development of bilateral shoulder strength, which may be particularly important in those with high ranges of ARC.
Topics: Adult; Biomechanical Phenomena; Cumulative Trauma Disorders; Humans; Male; Military Personnel; Muscle Strength; Range of Motion, Articular; Shoulder; Shoulder Injuries
PubMed: 29982689
DOI: 10.1093/milmed/usy088 -
Spine Deformity Aug 2020Retrospective.
STUDY DESIGN
Retrospective.
OBJECTIVES
To define normal values and distributions for sagittal, coronal, and shoulder balance among healthy adolescents, both for traditional radiographs and biplanar radiography. Our understanding of spine balance, especially in the sagittal plane, has expanded rapidly in recent years. Additionally, there has been growing use of simultaneous biplanar radiography which requires slightly different patient positioning. However, the normal ranges of several commonly used parameters have not yet been defined, either in traditional or biplanar radiography.
METHODS
Radiographs were retrospectively reviewed of 273 patients aged 10-18 years seen in spine clinics at two high-volume centers and not diagnosed with any spine pathology. One center utilized traditional radiography and the other biplanar radiography. Coronal, sagittal, and shoulder balance were measured for each patient. Intra-observer reliability and normal values with distributions were reported for each parameter.
RESULTS
Intra-observer reliability was excellent (intra-class correlation coefficients ≥ 0.98). Each parameter was normally distributed at each institution based on Kolmogorov-Smirnov testing. Sagittal balance was more negative at the institution using traditional radiographs (- 3.4 ± 4.2 vs. 0.3 ± 2.2, p < 0.001). Coronal balance was statistically, but not clinically, significantly more negative at this institution (- 0.6 ± 1.4 vs. - 0.2 ± 1.0, p = 0.007). Shoulder balance was not different between institutions. The "normal" ranges (mean ± 2 standard deviations, i.e., expected to include 95% of patients) were - 2.8 to 2.0 cm for coronal balance, - 9.0 to 6.1 cm for sagittal balance, and - 1.5-2.4 cm for shoulder balance.
CONCLUSIONS
In adolescents without known spine pathology, the mean coronal, sagittal, and shoulder balance is near neutral, but each parameter varies over a large range; so the average patient deviates from neutral by 1.0 ± 0.7 cm, 3.1 ± 2.6 cm, and 0.9 ± 0.7 cm, respectively. The most important difference between biplanar and traditional radiographs was a significantly more negative sagittal balance in the biplanar group which may be attributable to arm positioning.
LEVEL OF EVIDENCE
Level III.
Topics: Adolescent; Child; Female; Humans; Male; Patient Positioning; Postural Balance; Radiography; Reference Values; Retrospective Studies; Shoulder; Spine
PubMed: 32096131
DOI: 10.1007/s43390-020-00074-9 -
Journal of Electromyography and... Dec 2022We have previously demonstrated that fatigue at different locations impacts joint angles, angular variability, and coordination variability differently. However, the...
We have previously demonstrated that fatigue at different locations impacts joint angles, angular variability, and coordination variability differently. However, the neuromuscular control aspects underlying these kinematic changes have never been demonstrated. Seventeen young adults (8 males) were recruited. Electromyographic electrodes were placed on: upper trapezius, pectoralis major, anterior and middle deltoid, biceps and triceps brachii, and left and right erector spinae. Subjects performed the repetitive pointing task (RPT) at 1 Hz for 30 s before and after localized fatigue tasks, which consisted of one shoulder, one elbow and one lower back isometric fatiguing protocols until exhaustion in randomized order. Electromyographic amplitude (RMS), variability (SD) and mean power frequency (MnPF) were calculated for each of the pre-fatigue and post-fatigue RPT trials. There were sex × fatigue location interaction effects on upper trapezius RMS (p = 0.038) with males' values increasing the most after shoulder fatigue. Females' triceps brachii RMS was greater compared to males after shoulder, elbow, and trunk fatigue (p = 0.003, p = 0.001 and p = 0.007 respectively). There were sex × fatigue location effects on left erector spinae MnPF (p = 0.011) with males and females' values decreasing the most after trunk fatigue, but more so in males. Results demonstrate that males and females compensate differently during a repetitive pointing task when their elbows, shoulders and trunks are locally fatigued, which could have implications on sex-specific workplace injury risks. See Table 1 for acronyms.
Topics: Male; Young Adult; Female; Humans; Muscle Fatigue; Muscle, Skeletal; Shoulder; Arm; Elbow; Electromyography
PubMed: 36334403
DOI: 10.1016/j.jelekin.2022.102717 -
Sports Medicine and Arthroscopy Review Dec 2017The shoulder is the most inherently unstable joint in the body, prone to high rates of anterior dislocations with subsequent injuries to soft tissue and bony stabilizing... (Review)
Review
The shoulder is the most inherently unstable joint in the body, prone to high rates of anterior dislocations with subsequent injuries to soft tissue and bony stabilizing structures, resulting in recurrent shoulder instability. Advanced imaging utilizing magnetic resonance (MR) imaging and MR arthrography allows for thorough evaluation of lesions present in the unstable shoulder and is critical for preoperative planning. Arthroscopic shoulder stabilization in the appropriately selected patient can help restore stability and function. This review highlights correlations between MR imaging and arthroscopy of the most commonly reported soft tissue and bony injuries present in patients with shoulder instability.
Topics: Arthroscopy; Humans; Joint Instability; Magnetic Resonance Imaging; Shoulder
PubMed: 29095395
DOI: 10.1097/JSA.0000000000000163 -
Journal of Sport Rehabilitation Nov 2021Repetitive and asymmetric movements in tennis can result in biomechanical adaptation in shoulder joint. The aim of this study was to investigate the differences in...
PURPOSE
Repetitive and asymmetric movements in tennis can result in biomechanical adaptation in shoulder joint. The aim of this study was to investigate the differences in shoulder range of motion (ROM), strength, and functional performance tests between the dominant and nondominant shoulders, as well as to identify gender differences in junior tennis players.
METHODS
Forty-two junior tennis players (age mean: 11.3 [1.2] y, body mass index 18.3 [2.4] kg/m2) were included in the study. Shoulder internal rotation (IR), external rotation (ER) ROM, and total ROM, IR and ER isokinetic strength and closed kinetic chain upper-extremity stability, seated medicine ball throw used, grip hold tests were applied bilaterally. Paired sample t test and Student t test were used to compare the differences.
RESULTS
ER ROM was greater, while IR ROM and total ROM were lower on the dominant shoulder (all P values < .05). Nineteen players had glenohumeral IR deficit (IR ROM difference >13°). The players had a greater ER strength on the dominant side and similar IR strength between shoulders. There was significant difference in seated medicine ball throw results between the dominant and nondominant sides (P < .001). The mean distance for bilateral seated medicine ball throw was 377.02 (85.70) m, and closed kinetic chain upper-extremity stability results were calculated as a mean of 15.85 (1.72) touches. Differences between the genders: total ROM of the dominant shoulder was higher in female players (P = .045), the IR PT/BW at 60°/s angular speed was higher in male players' dominant shoulder (P = .030), and closed kinetic chain upper-extremity stability performance was higher in male players (P = .019).
CONCLUSIONS
Adolescent tennis players demonstrated differences in strength, ROM, and functional performance results between the dominant and nondominant shoulders. Gender differences were also seen in the aforementioned parameters in junior tennis players. Determining these differences may improve our understanding of sport-specific shoulder joint adaptations in tennis.
Topics: Adolescent; Female; Humans; Male; Physical Functional Performance; Range of Motion, Articular; Shoulder; Shoulder Joint; Tennis
PubMed: 34303312
DOI: 10.1123/jsr.2021-0038 -
Journal of Orthopaedic Research :... Oct 2022The Patient-Reported Outcomes Measurement Information System Upper Extremity Computer Adaptive Test (PROMIS UE CAT) is a newer patient-reported outcome measure for upper...
The Patient-Reported Outcomes Measurement Information System Upper Extremity Computer Adaptive Test (PROMIS UE CAT) is a newer patient-reported outcome measure for upper extremity physical function. To date, no longitudinal study exists assessing PROMIS UE CAT responsiveness in patients undergoing shoulder arthroplasty. The purpose of this prospective longitudinal study is to report PROMIS UE CAT responsiveness to change and correlation to legacy instruments in patients undergoing total shoulder arthroplasty (TSA). Ninety-six patients (97 shoulders) undergoing TSA completed the PROMIS UE, Oxford Shoulder Score (OSS), American Shoulder and Elbow Surgeons (ASES), and Simple Shoulder Test (SST) preoperatively and postoperatively at 6 weeks, 12 weeks, and after 6 months. Spearman's correlation coefficients (r) were calculated between PROMIS UE and other scores at each time-point. Responsiveness to change was assessed using the effect size (Cohen's d) and standardized response mean compared with the preoperative time-point. Floor and ceiling effects were also assessed. PROMIS UE CAT demonstrated positive responsiveness at all time-points after TSA. It demonstrated excellent correlation (range: 0.68-0.84) with ASES, SST, and OSS at all postoperative time-points, but the correlation was weaker (r < 0.6, except OSS) preoperatively. Only OSS and SST showed ceiling effects at the 6-12-month time-point (16.8% and 18.2%, respectively). PROMIS UE CAT responsiveness to change and strength of correlation with legacy instruments improves with time elapsed after TSA. Further quantification of meaningful responsiveness to change will require estimation of the minimal clinically important difference and substantial clinical benefit for PROMIS UE CAT.
Topics: Arthroplasty, Replacement, Shoulder; Patient Reported Outcome Measures; Prospective Studies; Shoulder; United States
PubMed: 35060155
DOI: 10.1002/jor.25263 -
Ergonomics Dec 2017The objective of this study was to determine how simulated manual wheelchair pushing influences biomechanical loading to the lumbar spine and shoulders. Sixty-two...
The objective of this study was to determine how simulated manual wheelchair pushing influences biomechanical loading to the lumbar spine and shoulders. Sixty-two subjects performed simulated wheelchair pushing and turning in a laboratory. An electromyography-assisted biomechanical model was used to estimate spinal loads. Moments at the shoulder joint, external hand forces and net turning torque were also assessed. Multiple linear regression techniques were employed to develop biomechanically based wheelchair pushing guidelines relating resultant hand force or net torque to spinal load. Male subjects experienced significantly greater spinal loading (p < 0.01), and spine loads were also increased for wheelchair turning compared to straight wheelchair pushing (p < 0.001). Biomechanically determined maximum acceptable resultant hand forces were 17-18% lower than psychophysically determined limits. We conclude that manual wheelchair pushing and turning can pose biomechanical risk to the lumbar spine and shoulders. Psychophysically determined maximum acceptable push forces do not appear to be protective enough of this biomechanical risk. Practitioner Summary: This laboratory study investigated biomechanical risk to the low back and shoulders during simulated wheelchair pushing. Manual wheelchair pushing posed biomechanical risk to the lumbar spine (in compression and A/P shear) and to the shoulders. Biomechanically determined wheelchair pushing thresholds are presented and are more protective than the closest psychophysically determined equivalents.
Topics: Adult; Biomechanical Phenomena; Electromyography; Ergonomics; Female; Hand; Humans; Lumbar Vertebrae; Lumbosacral Region; Male; Middle Aged; Muscle, Skeletal; Shoulder; Shoulder Joint; Torque; Wheelchairs; Young Adult
PubMed: 28627334
DOI: 10.1080/00140139.2017.1344445 -
Clinical Biomechanics (Bristol, Avon) Feb 2020Inertial sensors have the potential to provide objective and practical methods to assess joint and limb function in the clinical setting. The aim of this study is to...
BACKGROUND
Inertial sensors have the potential to provide objective and practical methods to assess joint and limb function in the clinical setting. The aim of this study is to evaluate the psychometric properties of inertial sensor metrics in the assessment of patients with subacromial shoulder pain.
METHODS
25 patients with unilateral subacromial shoulder pain and 50 control subjects were recruited. Assessments were carried out on both shoulders for all participants during a short movement procedure. Patients had assessments repeated after receiving three months of physiotherapy. Inertial metrics evaluated included a smoothness measure and speed and power scores derived from the range of angular velocity and acceleration profiles. Individual shoulder scores and asymmetry scores were both evaluated in terms of reliability, known-group validity, convergent validity and responsiveness.
FINDINGS
Regression analysis identified age to be a significant predictor for all scores, therefore an age matched sub-cohort of control subjects was used for comparative analyses. All scores demonstrated inter-rater reliability (ICC = 0.48-0.82), were able to differentiate pathological from healthy shoulders (AUC = 0.62-0.91) and displayed significant changes following treatment. Scores derived from the range of acceleration and velocity profiles demonstrated the largest effect sizes (Cohens d = 0.8-1.35), and displayed the highest correlation with the Oxford Shoulder Score (r = -0.40 - -0.58).
INTERPRETATION
The scores investigated demonstrate good psychometric properties and have potential to complement existing methods of assessment in the clinical or research setting. Further work is required to fully understand their clinical relevance and optimise assessment methods and interpretation.
Topics: Acceleration; Adult; Biomechanical Phenomena; Female; Humans; Male; Mechanical Phenomena; Middle Aged; Movement; Reproducibility of Results; Shoulder
PubMed: 31891822
DOI: 10.1016/j.clinbiomech.2019.12.010 -
Journal of Shoulder and Elbow Surgery Dec 2023Reverse shoulder arthroplasty (RSA) increases the moment arm of the deltoid; however, there is limited knowledge on the accompanying changes in muscle architecture that...
BACKGROUND
Reverse shoulder arthroplasty (RSA) increases the moment arm of the deltoid; however, there is limited knowledge on the accompanying changes in muscle architecture that play a role in muscle force production. The purpose of this study was to use a geometric shoulder model to evaluate the anterior deltoid, middle deltoid, and supraspinatus regarding (1) the differences in moment arms and muscle-tendon lengths in small, medium, and large native shoulders and (2) the impact of 3 RSA designs on moment arms, muscle fiber lengths, and force-length (F-L) curves.
METHODS
A geometric model of the native glenohumeral joint was developed, validated, and adjusted to represent small, medium, and large shoulders. Moment arms, muscle-tendon lengths, and normalized muscle fiber lengths were assessed for the supraspinatus, anterior deltoid, and middle deltoid from 0° to 90° of abduction. RSA designs were modeled and virtually implanted, including a lateralized glenosphere with an inlay 135° humeral component (lateral glenoid-medial humerus [LGMH]), a medialized glenosphere with an onlay 145° humeral component (medial glenoid-lateral humerus [MGLH]), and a medialized glenosphere with an inlay 155° humeral component (medial glenoid-medial humerus [MGMH]). Descriptive statistics were used to compare moment arms and normalized muscle fiber lengths.
RESULTS
As shoulder size increased, the moment arms and muscle-tendon lengths for the anterior deltoid, middle deltoid, and supraspinatus increased. All RSA designs achieved greater moment arms for the anterior and middle deltoid, with the MGLH design achieving the largest increase. The resting normalized muscle fiber length of the anterior and middle deltoid was substantially increased in the MGLH (1.29) and MGMH (1.24) designs, shifting the operating ranges of these muscles to the descending portions of their F-L curves, whereas the LGMH design maintained a resting deltoid fiber length (1.14) and operating range similar to the native shoulder. All RSA designs demonstrated a decrease in the native supraspinatus moment arm in early abduction, with the largest decrease in the MGLH design (-59%) and minimal decrease in the LGMH design (-14%). The supraspinatus operated on the ascending limb of its F-L curve in the native shoulder and remained on this portion of the F-L curve for all RSA designs.
CONCLUSION
Although the MGLH design maximizes the abduction moment arm for the anterior and middle deltoid, overlengthening of the muscle may compromise deltoid muscle force production by forcing the muscle to operate on the descending portion of its F-L curve. In contrast, the LGMH design increases the abduction moment arm for the anterior and middle deltoid more modestly while allowing the muscle to operate near the plateau of its F-L curve and maximizing its force-producing potential.
Topics: Humans; Shoulder; Arthroplasty, Replacement, Shoulder; Biomechanical Phenomena; Shoulder Joint; Muscle Fibers, Skeletal; Range of Motion, Articular
PubMed: 37419441
DOI: 10.1016/j.jse.2023.05.035 -
BMJ Open Jul 2023To investigate the effect of age-related rotator cuff tears on shoulder strength in a general population cohort. (Observational Study)
Observational Study
OBJECTIVES
To investigate the effect of age-related rotator cuff tears on shoulder strength in a general population cohort.
DESIGN
Cross sectional observational study.
SETTING
This study was set in an outpatient clinic setting in Chingford, North East London, and was a component of the 20 year visit of the Chingford 1000 women cohort.
PARTICIPANTS
Individuals were part of the Chingford 1000 women cohort, a 20-year-old longitudinal population study. This cohort has been extensively characterised as representative of the population of the UK. At the 20 year visit, 446 attended for shoulder assessment and were aged between 64 and 87.
PRIMARY AND SECONDARY OUTCOME MEASURES
Isometric shoulder abduction strength measured using a Nottingham Mecmesin Myometer and the presence of rotator cuff pathology, determined via ultrasound examination (GE voluson i portable ultrasound machine with a 10-16MHz linear probe). Shoulders were classified into normal, abnormal tendon/partial tear, full-thickness tears (>0 and ≤2.5 cm) and full-thickness tears (>2.5 cm). Symptoms were defined using the Oxford Shoulder Score, where an abnormal score was defined as symptomatic.
RESULTS
446 women (891 shoulders) aged 71 (range 65-84) were included in the study. Age, the presence of pain and the non-dominant arm were demonstrated to reduce strength. Rotator cuff tears and pathology had no isolated effect on shoulder strength in those aged under 70. However, in the over 70s full-thickness tears>0 and ≤2.5 cm, and >2.5 cm had mean reductions of 6.3 and 12.7 N, respectively (p<0.001).
CONCLUSION
Rotator cuff tears of all sizes in those aged under 70 were not associated with a loss of shoulder strength. In those aged over 70, strength was reduced by 30% with small and 40% with large full thickness tears. Loss in strength was associated a loss of ability to perform activities of daily living but only for large tears.
Topics: Aged; Humans; Female; Aged, 80 and over; Middle Aged; Young Adult; Adult; Shoulder; Rotator Cuff Injuries; Cross-Sectional Studies; Activities of Daily Living; Rotator Cuff
PubMed: 37460264
DOI: 10.1136/bmjopen-2023-071908