Shoulder abduction torque steadiness is preserved in subacromial impingement syndrome

Sex differences in torque steadiness, accuracy and activation of the shoulder girdle muscles during isometric shoulder scaption

Females present more neck/shoulder musculoskeletal disorders and have different activation strategies of the shoulder girdle muscles than males. However, the sensorimotor performance and potential sex differences are still largely unexplored. The aim of this study was to investigate sex differences in torque steadiness and accuracy during isometric shoulder scaption. We also examined the amplitude and variability of the activation of the trapezius, serratus anterior (SA), and anterior deltoid muscles during torque output evaluation. Thirty-four asymptomatic adults (17 females) participated. Torque steadiness and accuracy were evaluated during submaximal contractions at 20 % and 35 % of peak torque (PT). There was no sex difference in torque coefficient of variation, but females had significantly lower torque standard deviation (SD) values than males at the two intensities evaluated (p < 0.001) and lower torque median frequency values compared to males, regardless of intensity (p < 0.01). Females had significantly lower absolute error values than males for torque output at 35 %PT (p < 0.01) and lower constant error values compared to males, regardless of intensity (p = 0.01). Females had significantly higher muscle amplitude values than males, except for SA (p = 0.10) and in general, females showed higher muscle activation SD values compared to males (p < 0.05). Females may require more complex muscle activation patterns to achieve a more stable and accurate torque output. Therefore, these sex differences may reflect control mechanisms that may also be at play when explaining the greater risk of neck/shoulder musculoskeletal disorders in females than males.

Alterations in peripheral joint muscle force control in adults with musculoskeletal disease, injury, surgery, or arthroplasty: A systematic review and meta-analysis

PURPOSE

To systematically review and analyse whether musculoskeletal conditions affect peripheral joint muscle force control (i.e. magnitude and/or complexity of force fluctuations).

METHODS

A literature search was conducted using MEDLINE, CINAHL and SPORTDiscus databases (from inception-8th April 2021) for studies involving: 1) participants with musculoskeletal disease, injury, surgery, or arthroplasty in the peripheral joints of the upper/lower limb; 2) comparison with an unaffected control group or unaffected contralateral limb; and 3) measures of the magnitude and/or complexity of force fluctuations during targeted isometric contractions. The methodological quality of studies was evaluated using a modified Downs and Black Quality Index. Studies were combined using the standardized mean difference (SMD) in a random-effects model.

RESULTS

14 studies (investigating 694 participants) were included in the meta-analysis. There was a significant effect of musculoskeletal conditions on peripheral joint muscle force coefficient of variation (CV; SMD = 0.19 [95 % CI 0.06, 0.32]), whereby individuals with musculoskeletal conditions exhibited greater CV than controls. Subgroup analyses revealed that CV was only greater: 1) when comparison was made between symptomatic and asymptomatic individuals (rather than between affected and contralateral limbs; SMD = 0.22 [95 % CI 0.07, 0.38]); 2) for conditions of the knee (SMD = 0.29 [95 % CI 0.14, 0.44]); and 3) for ACL injury post-surgery (SMD = 0.56 [95 % CI 0.36, 0.75]).

CONCLUSION

Musculoskeletal conditions result in an increase in peripheral joint muscle force CV, with this effect dependent on study design, peripheral joint, and surgical status. The greater force CV is indicative of decreased force steadiness and could have implications for long-term tissue health/day-to-day function.

Effectiveness of proprioceptive neuromuscular facilitation and myofascial release techniques in patients with subacromial impingement syndrome

PURPOSE

To compare the effectiveness of proprioceptive neuromuscular facilitation and myofascial release technique in patients with subacromial impingement syndrome on pain, range of motion, muscle strength, quality of life, functionality and disability.

METHODS

Thirty patients were randomly divided into two groups: proprioceptive neuromuscular facilitation group (n = 15) and proprioceptive neuromuscular facilitation combined with myofascial release technique group (n = 15). Both treatment methods were performed 3 times a week for 4 weeks. Pain severity was assessed by Visuel Analog Scale, range of motion by a goniometer, muscle strength by digital hand dynamometer, quality of life by Nottingham health profile, functionality by arm, shoulder and hand problems questionnaire, disability by shoulder pain and disability index. All measurements were used before and after treatments. Pain severity, range of motion and muscle strength were also evaluated after the first session.

RESULTS

After the treatment, shoulder pain, range of motion, muscle strength, functionality and disability were improved in two groups (p < 0.05). Proprioceptive neuromuscular facilitation showed improvement in pain, whereas myofascial release technique improved pain, physical activity, emotional state, sleep and total dimensions of life quality (p < 0.05). Proprioceptive neuromuscular facilitation was more effective in reducing activity pain, whereas myofascial release technique was more effective in increasing flexion, external and internal rotation range of motion, flexion and abduction muscle strength after the first session (p < 0.05).

CONCLUSIONS

The combined application of proprioceptive neuromuscular facilitation and myofascial release technique has a more acute and cumulative positive effect on pain, range of motion, muscle strength, functionality, disability and quality of life in patients with subacromial impingement syndrome.

Can a simple fall cause a rotator cuff tear? Literature review and biomechanical considerations

Purpose

A simple fall on the shoulder is often referred to as minor trauma that cannot cause a tendon tear but at best reveal a pre-existing rotator cuff pathology. We wanted to know whether this statement was true. The purpose of our study was therefore to summarize the causes of acute rotator cuff tears reported in the literature and provide a biomechanical explanation for tendon tears diagnosed after a fall.

Method

We searched PubMed and included studies reporting rotator cuff tears occurring due to a trauma. The number of cases, the tendons involved, the age of the patients, and the nature of trauma were summarized. In addition, we noted any information provided by the authors on the pathogenesis of acute tendon ruptures.

Results

Sixty-seven articles with a total of 4061 traumatic rotator cuff tears met the inclusion criteria. A simple fall was the most common cause (725 cases) and the supraspinatus tendon was most frequently affected. The postulated pathomechanism is a sudden stretch of the tendon-muscle unit while contracting (eccentric loading).

Conclusion

A simple fall can cause an acute rotator cuff tear and fall-related tears are not restricted to young individuals. They can affect patients of any age. The stresses occurring within the rotator cuff during an attempt to cushion a fall may locally exceed the tensile strength of the tendon fibers and cause a partial or full-thickness tear.

Reduced force entropy in subacromial pain syndrome: A cross-sectional analysis

BACKGROUND

Generating a force at the hand requires moments about multiple joints by a theoretically infinite number of arm and shoulder muscle force combinations. This allows for learning and adaptation and can possibly be captured using the complexity (entropy) of an isometrically generated force curve. Patients with Subacromial Pain Syndrome have difficulty to explore alternative, pain-avoiding, motor strategies and we questioned whether loss of motor complexity may contribute to this. We assessed whether patients with Subacromial Pain Syndrome have reduced entropy of an isometrically generated abduction and adduction force curve.

METHODS

Forty patients and thirty controls generated submaximal isometric ab- and adduction force at the wrist. The force curve was characterized by the magnitude of force variability [standard deviation and coefficient of variation], and the entropy (complexity) of force variability [approximate entropy].

FINDINGS

Patients showed reduced entropy both during the abduction (-0.16, confidence interval: [-0.33; -0.00], p: 0.048) and adduction task (-0.20, confidence interval: [-0.37; -0.03], p: 0.024) and reduced force variability during abduction (standard deviation: -0.006, confidence interval: [-0.011; -0.001], p: 0.013 and coefficient of variation: -0.51, confidence interval: [-0.93; -0. 10], p: 0.016).

INTERPRETATIONS

Isometric force curves of patients with Subacromial Pain Syndrome show reduced complexity compared to asymptomatic controls, which may indicate more narrow and stereotype use of motor options. In future studies, it should be investigated whether the finding of reduced force (motor) entropy indicates functional decline, contributing to decreased ability to acquire and optimize motor strategies in Subacromial Pain Syndrome.

LEVEL OF EVIDENCE

Level II prognostic study.

Patients with Subacromial Pain Syndrome Present no Reduction of Shoulder Proprioception: A Matched Case-Control Study

BACKGROUND

Shoulder pain is common among patients with musculoskeletal pain and the prevalence of patients with subacromial pain syndrome (SAPS) is high. Despite the high prevalence, there is a lack of an extensive evaluation of the proprioception acuity in patients with SAPS. Knowledge of the proprioceptive deficit would assist clinicians in the proper treatment and may offer an alternative explanation for the mechanisms underlying SAPS, which are poorly understood.

OBJECTIVE

To compare the proprioceptive function of the shoulder in patients with SAPS and matched controls.

STUDY DESIGN

Matched case-control study.

SETTING

Physical Functional Rehabilitation Service of an outpatient clinic.

PARTICIPANTS

A total of 32 consecutive patients with SAPS who sought physical therapy for shoulder pain and 32 healthy participants (control group) matched for age, sex, and handedness.

INTERVENTIONS

All participants completed a questionnaire containing sociodemographic information, pain intensity and characteristics, the Numerical Pain Rating Scale, and the Shoulder Pain and Disability Index.

MAIN OUTCOME MEASUREMENTS

The proprioceptive assessment was performed through kinesthesia, passive joint position sense (PJPS), and the active joint position sense (AJPS).

RESULTS

The groups showed no statistically significant differences in kinesthesia, PJPS, and AJPS for internal or external rotation. The proprioceptive acuity was not associated with pain intensity or functional disability in patients with SAPS.

CONCLUSIONS

Participants with SAPS did not present proprioceptive deficits in a pain-free motion of medial and lateral rotation when compared to their matched controls. The proprioceptive deficit may not be involved with the mechanisms underlying SAPS and seems not to interfere with the clinical outcomes of patients with SAPS.

LEVEL OF EVIDENCE

Level III.

Subacromial Anesthetics Increase Proprioceptive Deficit in the Shoulder and Elbow in Patients With Subacromial Impingement Syndrome

Shoulder proprioception gives information regarding arm joint position and movement direction. Several studies have investigated shoulder proprioceptive acuity in patients with subacromial impingement syndrome (SIS); however, differences in protocols and between-subjects designs have limited scientific inferences regarding proprioception and SIS. We aimed to determine within-subject differences in shoulder and elbow proprioceptive acuity in 17 patients with stage 2 SIS following treatment of a local anesthetic injection. In addition, we used 17 healthy, age-, sex-, and arm dominance–matched controls to determine the magnitude of differences after treatment. Joint position sense (JPS) was measured before and after treatment in both groups in the sagittal plane for the shoulder and elbow. Our results indicate that patients with SIS have less sensitivity to angular position and tended to overshoot their targets with greater variability during angle-matching tasks for the shoulder (1.8° difference, P = .042) and elbow (5.6° difference, P = .001) than controls. The disparities in JPS found in patients with SIS were not resolved following subacromial injection; in fact, the magnitude of the errors increased after treatment where postinjection errors were significantly greater (P = .046) than controls, with an average difference of 2.4°. These findings suggest that patients with SIS have decrements in either the signaling or processing of proprioceptive information and may use pain to reduce these inequalities.

Torque steadiness and muscle activation are bilaterally impaired during shoulder abduction and flexion in chronic post-stroke subjects

OBJECTIVE

To characterize sensorimotor control and muscle activation in the shoulder of chronic hemiparetic during abduction and flexion in maximal and submaximal isometric contractions. Furthermore, to correlate submaximal sensorimotor control with motor impairment and degree of shoulder subluxation.

METHODS

Thirteen chronic hemiparetic post-stroke age-gender matched with healthy were included. Isometric torques were assessed using a dynamometer. Electromyographic activity of the anterior and middle deltoid, upper trapezius, pectoralis major and serratus anterior muscles were collected. Variables were calculated for torque: peak, time to target, standard deviation (SD), coefficient of variation (CV), and standard error (RMSE); for muscle activity: maximum and minimum values, range and coefficient of activation. Motor impairment was determined by Fugl-Meyer and shoulder subluxation was measured with a caliper.

RESULTS

Paretic and non-paretic limbs reduced peak and muscle activation during maximal isometric contraction. Paretic limb generated lower force when compared with non-paretic and control. Paretic and non-paretic presented higher values of SD, CV, RMSE, and CV for prime mover muscles and minimum values for all muscles during steadiness. No correlation was found between sensorimotor control, motor impairment and shoulder subluxation.

CONCLUSION

Chronic hemiparetic presented bilateral deficits in sensorimotor and muscle control during maximal and submaximal shoulder abduction and flexion.

Associations between biopsychosocial factors and chronic upper limb pain among slaughterhouse workers: cross sectional study

Background

Knowledge of factors associated with chronic pain is necessary for preventive strategies. The present study investigates biopsychosocial differences, with specific focus on rate of force development (RFD) and work ability, between workers with and without chronic upper limb pain.

Methods

Eighty-two male slaughterhouse workers, 49 with chronic upper limb pain and 33 pain-free controls participated in the study. Maximal muscle strength, RFD, and muscle activity was determined from fast and forceful maximal voluntary contractions for the shoulder and hand. Participants filled out a questionnaire on work ability (work ability index), work disability (Work module of DASH questionnaire), fear avoidance, and self-rated health. Additionally, pressure pain threshold (PPT) was measured in muscles of the arm, shoulder and lower leg.

Results

Muscle strength and RFD (determined within time intervals of 30, 50, 100, and 200 ms relative to onset of contraction) was 28 % and 58–78 % lower, respectively, in workers with chronic pain compared with pain-free controls, and paralleled by reduced muscle activity (all p < 0.001). Workers with chronic pain had lower PPT of the arm, shoulder and lower leg (p < 0.01), and reported impaired work ability index score and general health along with higher work disability and fear avoidance compared with controls (all p < 0.0001). No differences were observed between the groups in regard to age, BMI, physical activity level, job position and duration of slaughterhouse work (all p > 0.4).

Conclusions

Chronic upper limb pain was paralleled by reduced neuromuscular function of the shoulder and hand along with impaired work ability, work disability and general health. Future studies on chronic pain management at the workplace should carefully consider the biopsychosocial nature of pain when designing and implementing preventive strategies.

Influence of obstructive sleep apnea syndrome in the fluctuation of the submaximal isometric torque of knee extensors in patients with early-grade osteoarthritis

OBJECTIVE

The aim of this study was to investigate whether obstructive sleep apnea (OSA) alters the fluctuation of submaximal isometric torque of the knee extensors in patients with early-grade osteoarthritis (OA).

METHOD

The study included 60 male volunteers, aged 40 to 70 years, divided into four groups: Group 1 (G1) - Control (n=15): without OA and without OSA; Group 2 (G2) (n=15): with OA and without OSA; Group 3 (G3) (n=15): without OA and with OSA; and Group 4 (G4) (n=15) with OA and with OSA. Five patients underwent maximal isometric contractions of 10 seconds duration each, with the knee at 60° of flexion to determine peak torque at 60°. To evaluate the fluctuation of torque, 5 submaximal isometric contractions (50% of maximum peak torque) of 10 seconds each, which were calculated from the standard deviation of torque and coefficient of variation, were performed.

RESULTS

Significant differences were observed between groups for maximum peak torque, while G4 showed a lower value compared with G1 (p=0.005). Additionally, for the average torque exerted, G4 showed a lower value compared to the G1 (p=0.036). However, no differences were found between the groups for the standard deviation (p=0.844) and the coefficient of variation (p=0.143).

CONCLUSION

The authors concluded that OSA did not change the parameters of the fluctuation of isometric submaximal torque of knee extensors in patients with early-grade OA.

Shoulder internal and external rotations torque steadiness in overhead athletes with and without impingement symptoms

OBJECTIVES

This study aimed to investigate torque steadiness of shoulder internal and external rotations in regularly training overhead athletes with and without impingement symptoms.

DESIGN

Cross-sectional laboratory study.

METHODS

Three groups were evaluated: athletes with impingement symptoms (n=21), asymptomatic athletes (n=25) and non-athletes (n=21). To assess torque steadiness, the participants performed 3 submaximal contractions (35% of peak torque) for 10s each, with the arm at 90° of shoulder abduction and 90° of external rotation. The standard deviation, coefficient of variation, mean exerted torque and time to stability were measured from the steadiness trials.

RESULTS

The standard deviation of internal rotation was higher in asymptomatic athletes than in non-athletes (p<0.01); however, there was no difference between the athletes with impingement symptoms and the other groups. The other variables presented no differences among the groups.

CONCLUSIONS

Higher torque fluctuation of shoulder internal rotation in asymptomatic athletes may point to neuromuscular adaptations related to throwing training. However, the steadiness patterns of athletes with impingement symptoms did not differ from those of asymptomatic athletes or non-athletes.

The impact of rotator cuff tendinopathy on proprioception, measuring force sensation

BACKGROUND

The impact of rotator cuff tendinopathy and related impingement on proprioception is not well understood. Numerous quantitative and qualitative changes in shoulder muscles have been shown in patients with rotator cuff tendinopathy. These findings suggest that control of force might be affected. This investigation wants to evaluate force sensation, a submodality of proprioception, in patients with rotator cuff tendinopathy.

METHODS

Thirty-six patients with rotator cuff tendinopathy and 30 matched healthy subjects performed force reproduction tests to isometric external and internal rotation to investigate how accurately they could reproduce a fixed target (50% MVC). Relative error, constant error, and force steadiness were calculated to evaluate respectively magnitude of error made during the test, direction of this error (overshoot or undershoot), and fluctuations of produced forces.

RESULTS

Patients significantly overshoot the target (mean, 6.04% of target) while healthy subjects underestimate the target (mean, -5.76% of target). Relative error and force steadiness are similar in patients with rotator cuff tendinopathy and healthy subjects. Force reproduction tests, as executed in this study, were found to be highly reliable (ICC 0.849 and 0.909). Errors were significantly larger during external rotation tests, compared to internal rotation.

CONCLUSION

Patients overestimate the target during force reproduction tests. This should be taken into account in the rehabilitation of patients with rotator cuff tendinopathy; however, precision of force sensation and steadiness of force exertion remains unaltered. This might indicate that control of muscle force is preserved.

Joint position sense is not altered during shoulder medial and lateral rotations in female assembly line workers with shoulder impingement syndrome

This study evaluated joint position sense (JPS) during medial and lateral rotations of the shoulder in female workers with and without shoulder impingement syndrome (SIS). Three groups were assessed. The case group consisted of 15 female assembly line workers (35.5, SD 5.8 years) with unilateral SIS. Control group 1 consisted of 15 female assembly line workers asymptomatic for SIS (34.4, SD 5.5 years) and control group 2 consisted of 15 female subjects (33.1, SD 6.2 years) asymptomatic for SIS and with no exposure to activities with the upper limbs. The JPS was evaluated bilaterally during passive (2°/sec) and active (5°/sec) repositioning tests using an isokinetic dynamometer. The target angles were 45° of lateral rotation (achieved by medially rotating the shoulder from 90° of lateral rotation) and 75° of lateral rotation (achieved by laterally rotating the shoulder from neutral rotation). There were no differences between sides for all groups (p  >  0.05). There were no differences in any of the variables between the case group and the control groups (p  >  0.05). The results of this study suggest that JPS during medial and lateral rotations of the shoulder is not altered in female assembly line workers with SIS.

Effectiveness of microwave diathermy on pain, functional capacity, muscle strength, quality of life, and depression in patients with subacromial impingement syndrome: a randomized placebo-controlled clinical study

The aim of this clinical trial was to evaluate the effectiveness of therapeutic MD on pain, functional capacity, muscle strength, quality of life, and depression in patients with subacromial impingement syndrome (SIS). A total of 40 inpatient subjects with definite SIS were included in this study. These patients were sequentially randomized into 2 groups. Group 1 (n = 20) received therapeutic MD. Group 2 (n = 20) was served as control group and received sham MD. Superficial heat and exercise program were given to both groups. Both of the programs were performed 5 times weekly for 3 weeks. Patients were assessed before treatment (BT), after treatment (AT), and at a 1-month follow-up (F). Outcome measures included visual analogue scale, goniometry, Shoulder Pain and Disability Index, Shoulder Disability Questionnaire, shoulder isokinetic muscle testing, handgrip strength, Short Form 36, and Beck Depression Index. The patients with SIS in each group had significant improvements in pain, shoulder ROM, disability, shoulder muscles and grip strength, quality of life, and depression AT and F when compared with their initial status (P < 0.05). There was no statistically significant difference between the groups according to all the parameters regarding the change scores between AT-BT test and F-BT test (P > 0.05). A 2,450-MHz MD regimen showed no beneficial effects in patients with SIS, so the superficial heat and exercise program, as it is efficient, may be preferable for the treatment of SIS, alone.