Shoulder kinesthesia after anterior glenohumeral joint dislocation

Ageing and joint position sense of the asymptomatic shoulder: An observational study

PURPOSE

This study aimed to quantify the extent to which age was associated with joint position sense (JPS) of the asymptomatic shoulder as measured by joint position reproduction (JPR) tasks and assess the reproducibility of these tasks.

METHODS

120 Asymptomatic participants aged 18-70 years each performed 10 JPR-tasks. Both contralateral and ipsilateral JPR-tasks were evaluated on accuracy of JPR under active- and passive conditions at two levels within the shoulder forward flexion trajectory. Each task was performed three times. In a subgroup of 40 participants, the reproducibility of JPR-tasks was assessed one week after initial measurement. Reproducibility of JPR-tasks was evaluated by both reliability (intra-class correlation coefficients (ICC's)) and agreement (standard error of measurement (SEM)) measures.

RESULTS

Age was not associated with increased JPR-errors for any of the contralateral or ipsilateral JPR-tasks. ICC's ranged between 0.63 and 0.80 for contralateral JPR-tasks, and from 0.32 to 0.48 for ipsilateral tasks, except for one ipsilateral task where the reliability was similar to contralateral tasks (0.79). The SEM was comparable and small for all JPR-tasks, ranging between 1.1 and 2.1.

CONCLUSION

No age-related decline in JPS of the asymptomatic shoulder was found, and good agreement between test and re-test measurements for all JPR-tasks as indicated by the small SEM.

Delayed detection of passive motion in shoulders with a rotator cuff tear

The aim of this study was to test whether or not the threshold to the detection of passive motion (TTDPM) and passive joint position sense on the affected shoulder of patients with rotator cuff tear (RCT) was impaired compared to those on the unaffected side and to investigate the relationship between the tear size and changes in the TTDPM and passive joint position sense induced by RCT. This study included 21 patients with unilateral RCT before arthroscopic rotator cuff repair. To investigate proprioception in this study, we measured the TTDPM and passive joint position sense in abduction and external rotation using an isokinetic dynamometer. The tear size was evaluated intraoperatively under direct arthroscopic visualization. The TTDPM in abduction and external rotation was significantly longer on the affected side than on the unaffected side. However, the angular absolute error in passive joint position sense in abduction and external rotation was not significantly different between the limbs. A comparison according to the tear size impaired proprioception of the TTDPM in the larger tear group showed significantly longer values than in the smaller group. There was impaired proprioception of TTDPM in patients with RCT, and the impaired proprioception was related to tear severity. Impaired proprioception of TTDPM may inhibit consistent muscle recruitment to achieve precise control. Our results suggest that clinicians should consider proprioceptive exercises for impaired proprioception in their treatment for conservative or postoperative patients.

Proprioception: How is it affected by shoulder pain? A systematic review

INTRODUCTION

Proprioception encompasses the submodalities of joint position sense (JPS), kinesthesia, sense of force, and velocity. Owing to the vast mobility of the shoulder, it heavily relies on an intact sense of proprioception. Moreover, shoulder injuries are associated with a decreased sense of proprioception. What remains unclear is how shoulder proprioception is affected by pain and competing nociceptive senses.

PURPOSE OF THE STUDY

To summarize the literature evaluating the relationship between pain and shoulder proprioception.

METHODS

A literature review was conducted from inception until 22 October 2018, using electronic databases (PubMed, Web of Science, Scopus, EBSCO, CINAHL, and Embase). Retrieved citations were screened for eligibility, and methodological quality was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Eleven studies were included (n = 447 participants with shoulder pain, n = 20 with experimentally induced pain [EIP]/n = 600 painful shoulders and n = 20 [EIP]). The mean methodological quality of the studies was good (76%). Five studies investigated active JPS, four investigated passive JPS, six investigated kinesthesia, sense of force was measured in one study, and no study investigated sense of velocity. There is moderate evidence for impaired kinesthesia and low evidence for reduced sense of force among painful shoulders. Conflicting evidence is seen for the other proprioceptive submodalities.

CONCLUSION

The overall impact of pain on shoulder JPS remains unclear, while moderate evidence for an affected sense of kinesthesia is possible. There is low evidence for an impaired sense of force among painful shoulders. Standardization between studies is lacking, limiting the range of our conclusions. Further investigation is required into well-controlled and pain-induced studies to better understand the influence of pain on shoulder proprioception.

Development and validation of a shoulder-specific body-perception questionnaire in people with persistent shoulder pain

Background

There is evidence that people with persistent shoulder pain exhibit findings consistent with the presence of sensorimotor dysfunction. Sensorimotor impairments can manifest in a variety of ways, and further developing our understanding of sensorimotor dysfunction in shoulder pain may improve current models of care. The Fremantle Back Awareness Questionnaire (FreBAQ) has been developed to assess disturbed body perception specific to the back. The purpose of the present study was to develop a shoulder-specific self-perception questionnaire and evaluate the questionnaire in people with persistent shoulder pain.

Methods

The Fremantle Shoulder Awareness Questionnaire (FreSHAQ-J) was developed by modifying the FreBAQ. One hundred and twelve consecutive people with persistent shoulder pain completed the FreSHAQ-J. Thirty participants completed the FreSHAQ-J again two-weeks later to assess test-retest reliability. Rasch analysis was used to assess the psychometric properties of the FreSHAQ-J. Associations between FreSHAQ-J total score and clinical status was explored using correlational analysis.

Results

The FreSHAQ-J has acceptable category order, unidimensionality, no misfitting items, and excellent test-retest reliability. The FreSHAQ-J was moderately correlated with disability and pain catastrophization.

Conclusions

The FreSHAQ-J fits the Rasch measurement model well and is suitable for use with people with shoulder pain. Given the relationship between the FreSHAQ-J score and clinical status, change in body perception may be worth assessing when managing patients with shoulder pain.

Can a Conservative Rehabilitation Strategy Improve Shoulder Proprioception? A Systematic Review

CONTEXT

Proprioception deficits contribute to persistent and recurring physical disability, particularly with shoulder disorders. Proprioceptive training is thus prescribed in clinical practice. It is unclear whether nonsurgical rehabilitation can optimize shoulder proprioception.

OBJECTIVES

To summarize the available evidence of conservative rehabilitation (ie, nonsurgical) on proprioception among individuals with shoulder disorders.

EVIDENCE ACQUISITION

PubMed, Web of Science, and EBSCO were systematically searched, from inception until November 24, 2019. Selected articles were systematically assessed, and the methodological quality was established using the Dutch Cochrane Risk of Bias Tool and the Newcastle-Ottawa Quality Assessment Scale. The Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were utilized for this review. The conservative treatments were categorized as follows: (1) conventional therapy, (2) proprioceptive training, (3) elastic kinesiology tape, and (4) other passive therapies.

EVIDENCE SYNTHESIS

Twelve articles were included, yielding 58 healthy control shoulders and 362 shoulders affected by impingement syndrome, glenohumeral dislocations, nonspecific shoulder pain, rotator cuff dysfunction, or subluxation poststroke. The level of agreement between the evaluators was excellent (84.9%), and the studies were evaluated to be of fair to excellent quality (risk of bias: 28.5%-100%). This review suggests, with moderate evidence, that proprioceptive training (upper-body wobble board or flexible foil training) can improve proprioception in the midterm. No decisive evidence exists to suggest that conventional therapy is of added value to enhance shoulder proprioception. Conflicting evidence was found for the improvement of proprioception with the application of elastic kinesiology tape, while moderate evidence suggests that passive modalities, such as microcurrent electrical stimulation and bracing, are not effective for proprioceptive rehabilitation of the shoulder.

CONCLUSIONS

Proprioceptive training demonstrates the strongest evidence for the effective rehabilitation of individuals with a shoulder proprioceptive deficit. Elastic kinesiology tape does not appear to affect the sense of shoulder proprioception. This review suggests a possible specificity of training effect with shoulder proprioception.

Pressure pain sensitivity in patients with traumatic first-time and recurrent anterior shoulder dislocation: a cross-sectional analysis

Background and aims Traumatic anterior shoulder dislocation (ASD) is frequent in active populations and associated with a 39% higher risk of recurrent dislocation, which may cause persistent shoulder problems, pain, and impaired shoulder-related quality of life. While local and distant pressure pain sensitivity has been demonstrated in other shoulder conditions, little is known about the link between pressure pain sensitivity and ASD. The interesting aspect is whether recurrent dislocation - resulting in symptoms of longer duration - is associated with more pronounced pressure pain sensitivity, or if presence of pressure pain sensitivity may be part of the reasons why patients develop recurrent dislocation. Therefore, this study aimed at evaluating whether patients with recurrent ASD display greater pressure pain sensitivity and more painful body sites than patients with first-time ASD. Methods This was a cross-sectional analysis of baseline data from a randomized controlled trial including 34 patients with first-time ASD [82% male, mean (SD) age 26 (7) years] and 22 patients with recurrent ASD [96% male, mean (SD) age 25 (5) years]. Patients were assessed as follows: (1) assessment of local and distant pressure pain sensitivity evaluated by pressure pain thresholds (PPTs) using a handheld algometer on mm. trapezius superior, levator scapula, pectorales major, deltoideus, and tibialis anterior, (2) pain intensity at rest during the previous 24 h, (3) number of ASD, and (4) number of painful body sites on a region-divided body chart. Results The PPTs were not significantly different between first-time and recurrent ASD [mean (SD) kPa for m. trapezius superior 264 (110) vs. 261 (88), m. levator scapula 301 (157) vs. 325 (163), m. pectorales major 234 (163) vs. 269 (130), m. deltoideus 290 (166) vs. 352 (173), m. tibialis anterior 420 (202) vs. 449 (184)], two-way ANCOVA, adjusted for sex and age, F (4,263) = 0.29, p = 0.88. For both groups, the PPTs were lower at the shoulder sites than at m. tibialis anterior (difference 117-184 kPa, 95% CI range 33-267). Females had lower PPTs than males (difference 124 kPa, 95% CI 64-183). The number (SD) of painful body sites were 2.2 (1.9) for first-time ASD and 2.6 (5.4) for recurrent ASD, with no between-group differences, one-way ANCOVA, adjusted for sex and age, F (1, 52) = 0.24, p = 0.63. There was a strong correlation between PPTs at the shoulder and lower leg, r = 0.84, p < 0.01. Conclusions This study demonstrated no differences in local and distant pressure pain sensitivity or number of painful body sites between patients with first-time and recurrent ASD. Females had lower PPTs than males, and a strong correlation was found between PPTs at the shoulder and lower leg. Implications Patients with first-time and recurrent ASD seem to have similar pressure pain sensitivity, but lower PPTs compared to existing normative data, suggesting that it is relevant to evaluate the status of the pain system in these patients to prevent triggering or worsening of their symptoms. However, it remains unanswered how these changes affect the patients' ability to undergo rehabilitation, symptom response and long-term shoulder function.

Neuromuscular Exercises Improve Shoulder Function More Than Standard Care Exercises in Patients With a Traumatic Anterior Shoulder Dislocation: A Randomized Controlled Trial

Background:

There is an important gap in knowledge about the effectiveness of nonoperative treatment (exercise) for patients with traumatic primary and recurrent anterior shoulder dislocations (ASDs).

Purpose/Hypothesis:

The purpose of this study was to assess the efficacy and safety of physical therapist–supervised, shoulder instability neuromuscular exercise (SINEX) versus self-managed, home-based, standard care shoulder exercise (HOMEX) in patients with traumatic ASDs. The hypothesis was that SINEX would have a larger effect and fewer adverse events compared with HOMEX.

Study Design:

Randomized controlled trial; Level of evidence, 2.

Methods:

A total of 56 participants with radiographically verified, trauma-initiated primary or recurrent ASDs and self-reported decreased shoulder function were randomized to 12 weeks of either SINEX or HOMEX. The SINEX program consisted of 7 exercises, individually progressing from basic (2 × 20 repetitions each day) to elite (2 × 10 repetitions, 3 times weekly). The HOMEX program included 5 shoulder exercises performed 3 times weekly (2 × 10 repetitions). The primary outcome was the Western Ontario Shoulder Instability Index (WOSI) score, ranging from 0 (best possible) to 2100. The between-group minimal clinically important difference at 12 weeks was 250 points. Secondary outcomes included WOSI subdomain scores, patient-reported ratings of kinesiophobia and pain, objective shoulder function, patient satisfaction, and number of adverse events.

Results:

The between-group mean difference in the WOSI total score at 12 weeks significantly favored SINEX over HOMEX (–228.1 [95% CI, –430.5 to –25.6]). SINEX was furthermore superior to HOMEX in most of the secondary outcomes (3/4 subdomains of the WOSI and pain level during the past 7 days as well as clinical signs of anterior shoulder instability). Also, although not statistically significant, less than half the proportion of the SINEX patients compared with the HOMEX patients (3/27 [11%] vs 6/24 [25%], respectively; P = .204) underwent or were referred for shoulder stabilizing surgery. Satisfaction with both exercise programs was high, and no serious adverse events were reported.

Conclusion:

Neuromuscular shoulder exercise (SINEX) was superior to standard care exercise (HOMEX) in patients with traumatic ASDs. Further long-term follow-ups on treatment effects are needed.

Registration:

NCT02371928 (ClinicalTrials.gov identifier).

Patients with non-operated traumatic primary or recurrent anterior shoulder dislocation have equally poor self-reported and measured shoulder function: a cross-sectional study

Background

Patients with non-operated traumatic primary anterior shoulder dislocation (PASD) are assumed to have less shoulder impairment than patients with recurrent anterior shoulder dislocations (RASD). This may impact treatment decision strategy. The aim was to study whether patients with non-operated traumatic PASD have less shoulder impairment than those with RASD.

Methods

In a cross-sectional study baseline data from patients with PASD and RASD in a randomised controlled trial of non-operative shoulder exercise treatment were used. Shoulder function was self-reported (Western Ontario Shoulder Instability (WOSI), Tampa Scale of Kinesiophobia (TSK), General Health (EQ-5D-VAS), Numeric Pain Rating Scale (NPRS)), and measured (Constant-Murley shoulder Score (CMS total), CMS - Range of Motion (CMS-ROM, CMS – strength, proprioception, clinical tests).

Results

In total, 56 patients (34 (28 men) with PASD and 22 (21 men) with RASD) (mean age 26 years) participated. WOSI total was 1064 and 1048, and TSK above 37 (indicating high re-injury fear) was present in 33 (97%) and 21 (96%) of the groups with PASD and RASD, with no group difference. CMS total (66.4 and 70.4), CMS-ROM (28.7 and 31.5), CMS-strength (injured shoulder: 7.6 kg and 9.1 kg), proprioception and clinical tests were the same. Furthermore, 26 (76%) with PASD and 13 (59%) with RASD reported not to have received non-operative shoulder treatment.

Conclusions

Non-operated patients with PASD and self-reported shoulder trouble three-six weeks after initial injury do not have less shoulder impairment (self-reportedly or objectively measured) than non-operated patients RASD and self-reported shoulder trouble three-six weeks after their latest shoulder dislocation event.

Time to peak torque and acceleration time are altered in male patients following traumatic shoulder instability

BACKGROUND

Numerous authors have evaluated the strength of the rotator cuff muscles in patients with shoulder instability. However, only limited data are available with regard to neuromuscular control in patients with traumatic anterior shoulder instability, in particular at 90° of abduction. This study was designed to assess muscle strength and neuromuscular control ability using time to peak torque and acceleration time in nonathletic patients with traumatic anterior shoulder instability.

METHODS

Isokinetic muscle performance testing was performed in 20 male nonathletic anterior shoulder instability patients compared with 20 side-matched asymptomatic volunteers. Isokinetic muscle performance testing was performed at an angular velocity of 180°/s with 90° of shoulder abduction. Muscle strength and neuromuscular control (time to peak torque and acceleration time) of the internal rotators (IRs) and external rotators (ERs) were measured.

RESULTS

There were no significant differences in muscle strength of the IRs and ERs between the 2 groups. The injured shoulder showed delayed neuromuscular control in both the IRs and ERs in the instability patients compared with the normal control subjects (time to peak torque, P = .023 for IRs and P = .020 for ERs; acceleration time, P = .035 for IRs and P = .021 for ERs).

CONCLUSION

The neuromuscular control of both the IRs and ERs was decreased in male nonathletic patients with traumatic anterior shoulder instability even though muscle strength was not altered. Therefore, clinicians and therapists should implement exercises that aim to restore neuromuscular control in the rehabilitation of nonathletic patients with anterior shoulder instability.

A neuromuscular exercise programme versus standard care for patients with traumatic anterior shoulder instability: study protocol for a randomised controlled trial (the SINEX study)

Background

Anterior shoulder dislocation is a common injury and may have considerable impact on shoulder-related quality of life (QoL). If not warranted for initial stabilising surgery, patients are mostly left with little to no post-traumatic rehabilitation. This may be due to lack of evidence-based exercise programmes. In similar, high-impact injuries (e.g. anterior cruciate ligament tears in the knee) neuromuscular exercise has shown large success in improving physical function and QoL. Thus, the objective of this trial is to compare a nonoperative neuromuscular exercise shoulder programme with standard care in patients with traumatic anterior shoulder dislocations (TASD).

Methods/design

Randomised, assessor-blinded, controlled, multicentre trial. Eighty patients with a TASD will be recruited from three orthopaedic departments in Denmark. Patients with primary or recurrent anterior shoulder dislocations due to at least one traumatic event will be randomised to 12 weeks of either a standardised, individualised or physiotherapist-supervised neuromuscular shoulder exercise programme or standard care (self-managed shoulder exercise programme). Patients will be stratified according to injury status (primary or recurrent). Primary outcome will be change from baseline to 12 weeks in the patient-reported QoL outcome questionnaire, the Western Ontario Shoulder Instability Index (WOSI).

Discussion

This trial will be the first study to compare the efficacy and safety of two different nonoperative exercise treatment strategies for patients with TASD. Moreover, this is also the first study to investigate nonoperative treatment effects in patients with recurrent shoulder dislocations. Lastly, this study will add knowledge to the shared decision-making process of treatment strategies for clinical practice.

Trial registration

ClinicalTrials.gov, identifier: NCT02371928. Registered on 9 February 2015 at the National Institutes of Health Clinical Trials Protocol Registration System.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1830-x) contains supplementary material, which is available to authorized users.

Errors in Shoulder Joint Position Sense Mainly Come from the Glenohumeral Joint

While synchronous movement of the glenohumeral and scapulothoracic joints has been emphasized in previous kinematics studies, most investigations of shoulder joint position sense have treated the shoulder complex as a single joint. The purposes of this study were to investigate the joint position sense errors of the humerothoracic, glenohumeral, and scapulothoracic joints at different elevation angles and to examine whether the errors of the glenohumeral and scapulothoracic joints contribute to the errors of the humerothoracic joint. Fifty-one subjects with healthy shoulders were recruited. Active joint position sense of the humerothoracic, glenohumeral, and scapulothoracic joints was measured at 50°, 70°, and 90° of humerothoracic elevation in the scapular plane. The results showed that while scapulothoracic joint position sense errors were not affected by target angles, there was an angle effect on humerothoracic and glenohumeral errors, with errors decreasing as the target angles approached 90° of elevation. The results of a multiple regression analysis revealed that glenohumeral errors explained most of the variance of the humerothoracic errors and that scapulothoracic errors had a weaker predictive relationship with humerothoracic errors. Therefore, it may be necessary to test scapular joint position sense separately in addition to the assessment of the overall shoulder joint position sense.

Exercises focusing on rotator cuff and scapular muscles do not improve shoulder joint position sense in healthy subjects

Proprioception is essential for shoulder neuromuscular control and shoulder stability. Exercise of the rotator cuff and scapulothoracic muscles is an important part of shoulder rehabilitation. The purpose of this study was to investigate the effect of rotator cuff and scapulothoracic muscle exercises on shoulder joint position sense. Thirty-six healthy subjects were recruited and randomly assigned into either a control or training group. The subjects in the training group received closed-chain and open-chain exercises focusing on rotator cuff and scapulothoracic muscles for four weeks. Shoulder joint position sense errors in elevation, including the humerothoracic, glenohumeral and scapulothoracic joints, was measured. After four weeks of exercise training, strength increased overall in the training group, which demonstrated the effect of exercise on the muscular system. However, the changes in shoulder joint position sense errors in any individual joint of the subjects in the training group were not different from those of the control subjects. Therefore, exercises specifically targeting individual muscles with low intensity may not be sufficient to improve shoulder joint position sense in healthy subjects. Future work is needed to further investigate which types of exercise are more effective in improving joint position sense, and the mechanisms associated with those changes.

Efficacy of Proprioceptive Exercises in Patients with Subacromial Impingement Syndrome: A Single-Blinded Randomized Controlled Study

OBJECTIVE

The objective of this study was to evaluate the effectiveness of proprioceptive exercises on shoulder proprioception, range of motion, pain, muscle strength, and function in patients with subacromial impingement syndrome.

DESIGN

Sixty-one patients with subacromial impingement syndrome participated in this prospective, single-blind randomized controlled trial. All patients were randomly divided into two groups: control group (conventional physiotherapy, n = 30) and intervention group (proprioceptive exercise and conventional physiotherapy, n = 31). The primary outcome measures were sense of kinesthesia and active and passive repositioning for proprioception at 0 degrees and 10 degrees external rotation at 12 wks. The secondary outcome measures were pain at rest, at night, and during activities of daily living with the visual analog scale (0-10 cm), the Western Ontario Rotator Cuff index, the American Shoulder and Elbow Surgeons index, range of motion, and isometric muscle strength at both 6 and 12 wks.

RESULTS

After treatment, significant improvement was found in range of motion, pain, isometric muscle strength, kinesthesia at 0 degrees external rotation, and functional tests in both groups. The intervention group showed a significant improvement in kinesthesia at 10 degrees external rotation and active and passive repositioning at 10 degrees external rotation. When groups were compared, there were no statistically significant differences in any of the parameters at 12 wks.

CONCLUSIONS

Although proprioceptive exercises may provide better proprioceptive acuity, no additional positive effect on other clinical parameters was observed.

Upper limb joint position sense during shoulder flexion in healthy individuals: a pilot study to develop a new assessment method

BACKGROUND

Altered shoulder joint position sense (JPS) following shoulder injury has been demonstrated in the literature and may increase the risk of injury. A JPS assessment targeting the shoulder will provide the clinician with an objective marker. The present study aimed to develop an assessment method of JPS using an active relocation test (ART).

METHODS

In total, 40 healthy participants were recruited. A laser-pointer attached to the index finger during an ART allowed measurement (mm) of JPS by measuring the distance between the target and relocated position. Participants were blindfolded and stood an arm's length (approximately 1 m) away from the wall. Whilst keeping the wrist in neutral and elbow extended, the participant actively moved to the target position (90° glenohumeral flexion), held for 5 seconds, returned their arm to their side and actively returned to the target position. A mean was calculated from three trials to provide an ART score.

RESULTS

The mean (SD) dominant and nondominant ART score was 89.2 (SD 35.5) mm (95% confidence interval = 77.87 mm to 100.5 mm) and 94.1 (34.5) mm (95% confidence interval = 83.1 mm to 105.2 mm), respectively. Arm dominance did not significantly affect ART scores.

CONCLUSIONS

No significant difference was demonstrated between the dominant and nondominant arm using an ART assessing JPS acuity. Further studies are needed to establish inter-rater and intra-rater reliability.

The effect of experimentally-induced subacromial pain on proprioception

Shoulder injuries may be associated with proprioceptive deficits, however, it is unknown whether these changes are due to the experience of pain, tissue damage, or a combination of these. The aim of this study was to investigate the effect of experimentally-induced sub-acromial pain on proprioceptive variables. Sub-acromial pain was induced via hypertonic saline injection in 20 healthy participants. Passive joint replication (PJR) and threshold to detection of movement direction (TTDMD) were assessed with a Biodex System 3 Pro isokinetic dynamometer for baseline control, experimental pain and recovery control conditions with a starting position of 60° shoulder abduction. The target angle for PJR was 60° external rotation, starting from 40°. TTDMD was tested from a position of 20° external rotation. Repeated measures ANOVAs were used to determine differences between PJR absolute and variable errors and TTDMD for the control and experimental conditions. Pain was elicited with a median 7 on the Numeric Pain Rating Scale. TTDMD was significantly decreased for the experimental pain condition compared to baseline and recovery conditions (≈30%, P = 0.003). No significant differences were found for absolute (P = 0.152) and variable (P = 0.514) error for PJR. Movement sense was enhanced for the experimental sub-acromial pain condition, which may reflect protective effects of the central nervous system in response to the pain. Where decreased passive proprioception is observed in shoulders with injuries, these may be due to a combination of peripheral tissue injury and neural adaptations that differ from those due to acute pain.

The effects of shoulder injury on kinaesthesia: a systematic review and meta-analysis

The aim of this systematic review was to synthesize the evidence for changes for proprioceptive variables consisting of movement and position sense in participants with glenohumeral musculoskeletal disorders. Five databases were searched until 13th August 2013. Methodological quality was assessed and meta-analyses were performed for active and passive joint reposition sense (AJPS and PJPS) and movement sense, determined with threshold to detection of passive motion (TTDPM). The search yielded 17 studies, four of which were classified as having high methodological quality, seven as moderate and six as low quality. For participants with post-traumatic glenohumeral instability, pooled findings indicate moderate evidence for higher TTDPM for involved shoulders compared to control groups and the contralateral uninvolved side, indicating decreased movement sense. For AJPS and PJPS there was moderate to limited evidence for significant increased errors for involved compared to uninvovled shoulders, but not when compared to the control groups. Limited evidence was found for decreased AJPS acuity for patients with chronic rotator cuff pain and for patients with unspecified shoulder pain compared to healthy controls. Movement sense is most likely to be impaired after shoulder injury involving post-traumatic instability when compared to the contralateral shoulder and to controls, while deficits for AJPS and PJPS are more likely to be evident compared to the contralateral shoulder in participants with glenohumeral musculoskeletal disorders.

Injury and lumbar reposition sense in cricket pace bowlers in neutral and pace bowling specific body positions

BACKGROUND AND CONTEXT

The cricket pace bowling action consists of a complex sequence of forceful actions, involving practiced, particular movements of the lumbar spine. The nature and repetition of the pace bowling action is known to be associated with a high incidence of low back injuries.

PURPOSE

This study aimed to establish whether lumbar proprioception (as measured by joint position sense) in the neutral lumbar spine position as well as lumbar positions corresponding to those at front foot placement and ball release positions of the cricket pace bowling action were related to previous injury and injury sustained during the cricket season under review. Injuries specifically sustained during the bowling action and those specific to the low back were explicitly investigated.

STUDY SETTING

Longitudinal study with participants tested at the start and monitored over the duration of a cricket season.

PARTICIPANT SAMPLE

Seventeen male cricket pace bowlers between the ages of 18 and 26 years participated in this study.

OUTCOME MEASURES

Physiological outcome measures were used. Lumbar position sense was established using electrogoniometry.

METHODS

Lumbar reposition error was measured in three positions (neutral lumbar spine, front foot placement, and ball release bowling positions). In each position, lumbar orientation was determined in the sagittal (flexion-extension) and coronal (left-right lateral flexion) planes. Wilcoxon matched-pairs ranks and Kruskal-Wallis tests were used to establish the relationship between variables.

RESULTS

Reposition error was associated with general injuries sustained in the past and during the cricket season under review, low back injuries, as well as injuries sustained during the bowling action (p<.05).

CONCLUSION

Lumbar position sense, as a measure of proprioception, was related to injury in general, injuries sustained during the bowling action, and, especially, low back injury sustained in the past. Low back injury prevention methods are particularly needed because of the high load nature of the pace bowling action. If the proprioception of the lumbar spine is improved in pace bowlers, their risk of lumbar injury can potentially be reduced.

Movement control in patients with shoulder instability: a comparison between patients after open surgery and nonoperated patients

BACKGROUND

Open surgery to correct shoulder instability is deemed to facilitate recovery of static and dynamic motor functions. Postoperative assessments focus primarily on static outcomes (e.g., repositioning accuracy). We introduce kinematic measures of arm smoothness to assess shoulder patients after open surgery and compare them with nonoperated patients. Performance among both groups of patients was hypothesized to differ. Postsurgery patients were expected to match healthy controls.

METHODS

All participants performed pointing movements with the affected/dominant arm fully extended at fast, preferred, and slow speeds (36 trials per subject). Kinematic data were collected (100 Hz, 3 seconds), and mixed-design analyses of variance (group, speed) were performed with movement time, movement amplitude, acceleration time, and model-observed similarities as dependent variables. Nonparametric tests were performed for number of velocity peaks.

RESULTS

Nonoperated and postsurgery patients showed similarities at preferred and faster movement speeds but not at slower speed. Postsurgery patients were closer to maximally smoothed motion and differed from healthy controls mainly during slow arm movements (closer to maximal smoothness, larger movement amplitude, shorter movement time, and lower number of peaks; i.e., less movement fragmentation).

CONCLUSIONS

Arm kinematic analyses suggest that open surgery stabilizes the shoulder but does not necessarily restore normal movement quality. Patients with recurrent anterior shoulder instability (RASI) seem to implement a "safe" but nonadaptive mode of action whereby preplanned stereotypical movements may be executed without depending on feedback. Rehabilitation of RASI patients should focus on restoring feedback-based movement control. Clinical assessment of RASI patients should include higher order kinematic descriptors.

Nonoperative and postoperative rehabilitation for glenohumeral instability

The glenohumeral joint is an inherently unstable joint that relies on the interaction of the dynamic and static stabilizers to maintain stability. Disruption of this interplay or poor development of any of these factors may result in instability, pain, and a loss of function. Rehabilitation will vary based on the type of instability present and the key principles described. Whether a course of nonoperative rehabilitation is followed or the patient presents postoperatively, a comprehensive program designed to establish full ROM and balance capsular mobility, in addition to maximizing muscular strength, endurance, proprioception, dynamic stability, and neuromuscular control is essential. A functional approach to rehabilitation using movement patterns and sport-specific positions along with an interval sport program will allow a gradual return to athletics. The focus of the program should minimize the risk of recurrence and ensure that the patient can safely return to functional activities.

Soothing suffering swimmers: a systematic review of the epidemiology, diagnosis, treatment and rehabilitation of musculoskeletal injuries in competitive swimmers

BACKGROUND

This review details the examination, diagnosis, treatment and management of injuries encountered by competitive swimmers. Primarily, these involve the shoulder, however, the spine, knee and hip can be involved. Using the Coleman methodology score, we show that the methods used in obtaining and reporting clinical findings and intervention results could be improved. Where possible, we suggest improvements.

SOURCES OF DATA

A literature review was conducted in English, Italian, French and German using PubMed, Google Scholar and Ovid search engines with strict inclusion/exclusion criteria.

AREAS OF AGREEMENT

Poor technique, and high training intensity and distance are the most common cause of missed swim practice and competition through injury.

AREAS OF CONTROVERSY

Few articles agree on a single method of each of clinical examination, diagnosis, treatment and rehabilitation.

GROWING POINTS

Articles are consistently retrospective with few investigating spine, hip and knee injuries.

AREAS TIMELY FOR DEVELOPING RESEARCH

Clinical findings and rehabilitation methods should be reported using a more structured method possibly based on the Coleman methodological scoring system.

Shoulder position sense during passive matching and active positioning tasks in individuals with anterior shoulder instability

BACKGROUND

Altered neuromuscular control due to compromised joint position sense may contribute to recurrent shoulder instability.

OBJECTIVE

The purpose of the present study was to examine whether individuals with anterior shoulder instability exhibit larger shoulder position sense errors than those with healthy shoulders in both passive matching and active positioning.

DESIGN

This was a between-groups study with repeated measures.

METHODS

Ten people with anterior shoulder instability and 15 people with healthy shoulders participated in the study. Shoulder position sense was examined with 3 different protocols (passive motion to remembered shoulder rotation angles and active shoulder abduction and rotation to verbally specified positions) in positions of both mid-range and end-range of motion.

RESULTS

Participants with unstable shoulders exhibited significantly larger errors (by 1.8° on average) in perception of shoulder position compared with those with healthy shoulders during passive matching. During active positioning, participants with unstable shoulders were able to voluntarily move the shoulder to verbally specified angles as accurately as those with healthy shoulders in both abduction (0.85° difference) and rotation (0.99° difference) tasks.

CONCLUSIONS

Results of this study indicate that people with unstable shoulders can perceive shoulder angles as accurately as people with healthy shoulders in activities with voluntary arm movements. Compared with passive matching, better information from muscle spindles and other sources during voluntary arm movements may compensate for the potential joint position sense deficits after the injury. Therefore, individuals with an unstable shoulder may have adequate neuromuscular control to engage proper protective mechanisms to stabilize the shoulder joint during functional activities.

Comparison of muscle activation levels during arm abduction in the plane of the scapula vs. proprioceptive neuromuscular facilitation upper extremity patterns

This study quantified activation of 8 muscles of the shoulder, trunk, and back during standing performance of (a) arm abduction in the plane of the scapula (scaption), (b) proprioceptive neuromuscular facilitation (PNF) diagonal 1 flexion (D1F), and (c) PNF diagonal 2 flexion (D2F) while lifting a dumbbell with the dominant hand. Twelve men (26.1 ± 4.4 years) and 13 women (24.5 ± 1.9 years) volunteered to participate. Electromyographic signals were collected with DE-3.1 double-differential surface electrodes at a sampling frequency of 1,000 Hz. Electromyographic signals were normalized to peak activity in the maximum voluntary isometric contraction (MVIC) trial and expressed as a percentage. One-way repeated-measures analysis of variance with Bonferroni corrections (α = 0.05) examined muscle activation patterns across the 3 conditions. For the middle trapezius, average activation was greater (p < 0.001) for D2F (70.5 ± 23.4% MVIC) than D1F (46.4 ± 19.6% MVIC). Lower trapezius average activation was greater (p < 0.001) for D2F (55.3 ± 23.8% MVIC) than D1F (40.1 ± 16% MVIC). The anterior deltoid showed greater activation (p = 0.009) for scaption (92.4 ± 26% MVIC) than D1F (74.4 ± 21.4% MVIC). The erector spinae showed greater activation for D2F (34.2 ± 12% MVIC; p < 0.001) and D1F (41.7 ± 21.4% MVIC; p < 0.001) than scaption (14.5 ± 12.3% MVIC). During D2F and scaption, all 6 muscles of the shoulder complex demonstrated very high activation levels (>60% MVIC) with the exception of the lower trapezius (55% MVIC). In contrast, erector spinae and external oblique muscles exhibited moderate activation (21-40% MVIC) during arm elevation. The 6 muscles of the shoulder complex displayed high to very high muscle activation at a level appropriate for strength training during all 3 exercise conditions.

Measurement of active shoulder proprioception: dedicated system and device

Proprioception is an essential part of shoulder stability and neuromuscular control. The purpose of the study was the development of a precise system of shoulder proprioception assessment in the active mode (Propriometr). For that purpose, devices such as the electronic goniometer and computer software had been designed. A pilot study was carried out on a control group of 27 healthy subjects, the average age being 23.8 (22–29) in order to test the system. The result of the assessment was the finding of the error of active reproduction of the joint position (EARJP). EARJP was assessed for flexion, abduction, external and internal rotation. For every motion, reference positions were used at three different angles. The results showed EARJP to range in 3–6.1°. The proprioception evaluation system (propriometr) allows a precise measurement of active joint position sense. The designed system can be used to assess proprioception in both shoulder injuries and treatment. In addition, all achieved results of normal shoulders may serve as reference to be compared with the results of forthcoming studies.

EVALUATION OF INTERNAL ROTATOR MUSCLE FATIGUE ON SHOULDER AND SCAPULAR PROPRIOCEPTION

Background and aim: Fatigue of internal or external rotators of the glenohumeral may alter proprioception in the shoulder joint. Fatigue of shoulder muscles can affect the three-dimentional kinematics of the scapula, and may also alter the glenohumeral and scapular movement pattern, with changes in the scapulohumeral rhythm. Previous studies have shown that with arm elevation, there is a decreased upward rotation of the scapula as well as reduced posterior tilt and external rotation movements with shoulder rotator cuff muscle fatigue. Our aim is to examine the effect of internal rotator fatigue on the proprioception of glenohumeral and scapular active repositioning. Methods: Twenty young healthy subjects with an average age of 20 years were recruited. Each subject performed repetitive concentric exercise (internal rotation) to induce muscles fatigue, which was confirmed by a muscle strength testing using a hand-held dynamometer. Measurement of active repositioning with glenohumeral and scapula repositioning were examined before and after internal rotator fatigue via the three-dimensional (3D) electromagnetic motion analysis system. Results: Fatigue of internal rotators did not affect the glenohumeral and thoracoscapluar joint proprioception (P > 0.05). Conclusion: The findings showed that fatigue of shoulder internal rotators did not contribute to alteration in glenohumeral and scapular proprioception.

Impaired joint proprioception at higher shoulder elevations in chronic rotator cuff pathology

OBJECTIVES

To assess the degree of impairment of shoulder proprioceptive acuity in individuals with chronic rotator cuff pathology (CRCP), and to examine the effect of impingement-related shoulder pain on acuity using a reliable laboratory technique.

DESIGN

Case-control study.

SETTING

University human movement laboratory.

PARTICIPANTS

A volunteer sample of individuals with CRCP (n=26) were recruited and screened, and compared with age-, sex-, and limb dominance-matched individuals (n=30) who acted as controls. Ten participants with CRCP underwent repeat assessment after 2 days to determine the intrarater reliability of proprioceptive measurement.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Each participant underwent assessment of joint position sense at 40° and 100° of scapular plane abduction using an active position-matching task. Movements were recorded with reflective skin markers and a multidimensional motion analysis system. Self-reported pain intensity associated with the procedure was recorded with a visual analog scale.

RESULTS

Intraclass correlation coefficients (model 3,5) between repeat assessments ranged from .54 to .99. On average, those with CRCP demonstrated reduced acuity at 40° and 100° test angles. In comparison with the control group, proprioceptive acuity was significantly impaired (P<.01) at the 100° test angle, where the pain intensity was significantly greater (P<.01).

CONCLUSIONS

This study demonstrated impairment of shoulder joint position sense in CRCP. The degree of proprioceptive impairment was greatest at higher elevations in the setting of increased shoulder impingement and pain, which may serve to perpetuate the pathology. These findings provide a theoretic rationale for the continued implementation of proprioceptive rehabilitation programs in managing CRCP.

Active stiffness and strength in people with unilateral anterior shoulder instability: a bilateral comparison

CONTEXT

Active muscle stiffness might protect the unstable shoulder from recurrent dislocation.

OBJECTIVE

To compare strength and active stiffness in participants with unilateral anterior shoulder instability and to examine the relationship between active stiffness and functional ability.

DESIGN

Cross-sectional study.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Participants included 16 males (age range, 16-40 years; height = 179.4 ± 6.1 cm; mass = 79.1 ± 6.8 kg) with 2 or more episodes of unilateral traumatic anterior shoulder instability.

MAIN OUTCOME MEASURE(S)

Active stiffness and maximal voluntary strength were measured bilaterally in participants. In addition, quality of life, function, and perceived instability were measured using the Western Ontario Stability Index, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, and Single Alpha Numeric Evaluation, respectively.

RESULTS

We found less horizontal adduction strength (t(15) = -4.092, P = .001) and less stiffness at 30% (t(14) = -3.796, P = .002) and 50% (t(12) = -2.341, P = .04) maximal voluntary strength in the unstable than stable shoulder. Active stiffness was not correlated with quality of life, function, or perceived instability (r range, 0.0-0.25; P > .05).

CONCLUSIONS

The observed reduction in stiffness in the unstable shoulder warrants inclusion of exercises in the rehabilitation program to protect the joint from perturbations that might lead to dislocation. The lack of association between active stiffness and quality of life, function, or perceived instability might indicate that stiffness plays a less direct role in shoulder stability.

Recovery of shoulder strength and proprioception after open surgery for recurrent anterior instability: a comparison of two surgical techniques

BACKGROUND

Previous studies have documented a decrease in proprioceptive capacity in the unstable shoulder. The degree to which surgical approach affects recovery of strength and proprioception is unknown.

MATERIALS AND METHODS

The recovery of strength and proprioception after open surgery for recurrent anterior glenohumeral instability was compared for 2 surgical procedures. A prospective analysis of 55 consecutive patients with posttraumatic unilateral recurrent anterior glenohumeral instability was performed. Thirty patients (group 1) underwent an open inferior capsular shift with detachment of the subscapularis, and 25 (group 2) underwent an anterior capsulolabral reconstruction.

RESULTS

Mean preoperative proprioception and strength values were significantly lower for the affected shoulders in both groups. At 6 months after surgery, there were no significant differences for mean strength and proprioception values between the unaffected and operative sides for group 2 patients. In group 1 patients, however, there were still significant deficits in mean position sense and strength values. Complete restoration of proprioception and strength, however, was evident by 12 months in group 1.

CONCLUSION

This study demonstrates that there are significant deficits in both strength and proprioception in patients with posttraumatic, recurrent anterior glenohumeral instability. Although both are completely restored by 1 year after surgery, a subscapularis-splitting approach allows for complete recovery of strength and position sense as early as 6 months postoperatively. Detachment of the subscapularis delays recovery of strength and position sense for up to 12 months after surgery.

Current concepts in rehabilitation following ulnar collateral ligament reconstruction

Injuries to the ulnar collateral ligament (UCL) in throwing athletes frequently occurs from the repetitive valgus loading of the elbow during the throwing motion, which often results in surgical reconstruction of the UCL requiring a structured postoperative rehabilitation program. Several methods are currently used and recommended for UCL reconstruction using autogenous grafts in an attempt to reproduce the stabilizing function of the native UCL. Rehabilitation following surgical reconstruction of the UCL begins with range of motion and initial protection of the surgical reconstruction, along with resistive exercise for the entire upper extremity kinetic chain. Progressions for resistive exercise are followed that attempt to fully restore strength and local muscular endurance in the rotator cuff and scapular stabilizers, in addition to the distal upper extremity musculature, to allow for a return to throwing and overhead functional activities. Rehabilitation following UCL reconstruction has produced favorable outcomes, allowing for a return to throwing in competitive environments.

A new measurement method for spine reposition sense

Background

A cost effective tool for the measurement of trunk reposition sense is needed clinically. This study evaluates the reliability and validity of a new clinical spine reposition sense device.

Methods

The first part of this three part investigation included 45 asymptomatic subjects examined in the first 20 repeated trials portion assessing spine reposition sense. The second portion, test-retest, examined 57 asymptomatic subjects. Initial testing consisted of subjects sitting on the device and performing 20 trials of a self-determined 2/3 trunk flexion position. The second portion of the study involved 7 trials of trunk flexion performed twice. The angular position for each trial was calculated and the mean reposition error from the initial 2/3 position was determined. For the third portion, the new device was compared to the Skill Technologies 6D (ST6D) Imperial Motion Capture and Analysis System.

Results

ICC (3,1) for trials 4–7 was 0.79 and 0.76 for time one and time two, respectively and the test-retest ICC (3,k) was 0.38. Due to the poor test-retest ICC, the Bland Altman method was used to compare test and retest absolute errors. Most measurement differences were small and fell within the 95% confidence interval. Comparable measures between the two methods were found using the Bland Altman method to compare the reposition sense device to the ST6D system.

Conclusion

The device may be a cost effective clinical technique for sagittal trunk reposition sense measurement.

The effect of joint instability on latency and recruitment order of the shoulder muscles

Several shoulder dysfunctions are generally characterized as Shoulder Impingement Syndrome (SIS). Specifically, glenohumeral instability (GI) has been viewed as a primary cause of SIS in young individuals, mainly in overhead athletics. Past studies have associated GI with modifications in latency, recruitment order and/or EMG activity. However, it is not clear if pain and/or joint instability can account for these observed changes. The aim of this investigation was to analyze the effect of glenohumeral instability on the latencies and recruitment order of the superficial muscles of the glenohumeral and scapulothoracic joints in swimmers without pain symptom. Eight individuals with and eight without history of Shoulder Impingement Syndrome performed bilateral and simultaneous shoulder elevations at three different distances. The shoulder kinematics and EMG activities of glenohumeral and scapulothoracic muscles were registered. Results showed that subjects of both groups performed the task with similar latencies and recruitment order of the muscle activities. We conclude that shoulder instability does not necessarily affect the latencies and recruitment order of the shoulder muscles during the elevation of the shoulder in the scapular plane. Pain and other factors may be involved in the kinematics and electromyographic alterations demonstrated in other experiments.

Muscle activation and cutaneous reflex modulation during rhythmic and discrete arm tasks in orthopaedic shoulder instability

In orthopaedic shoulder instability, muscle activity (EMG) is altered during unconstrained discrete arm movement tasks (e.g. elevation against a load). These findings have been ascribed to deficits in afferent feedback and neural control with glenohumeral instabilities resulting from orthopaedic injury. However, the integrity of neural control during shoulder movements in those with unstable shoulders is unclear. It is not known if there are altered EMG patterns during rhythmic arm movement or during discrete tasks involving no load, as would be experienced in many arm motions performed in daily living. The primary objective of this study was to evaluate neural control of arm movements between those with unstable shoulders and control participants, within a constrained arm movement paradigm involving both rhythmic arm cycling and discrete reaching. To achieve this objective, we determined if the amplitude and timing of EMG related to the movement pattern (background EMG) was significantly different between groups. Cutaneous reflexes were used to simulate a perturbation to the upper limb that would typically evoke a coordinated response. In the elevation phase of the movement path for anterior and posterior deltoid, upper trapezius, infraspinatus and serratus anterior, background EMG during rhythmic arm cycling was significantly (24%, p < 0.05) larger in unstable shoulders than in controls. No differences were found in background EMG between the groups during the discrete task. Significant differences (p < 0.05) were also noted in cutaneous reflexes between groups for both the rhythmic and discrete tasks with the reflex amplitudes being either increased or reduced in unstable shoulders as compared to controls. The differences in the background EMG and the cutaneous reflexes patterns in those with shoulder instabilities suggest that neural control is altered during rhythmic movement.

Recovery of Joint Position Sense in the Shoulder after Muscle Fatigue

Context:

Fatigue of the shoulder rotator muscles may negatively affect joint position sense (JPS) and ultimately lead to injury.

Objective:

Recovery of shoulder JPS after muscle fatigue.

Design:

A repeated-measures study.

Setting:

Musculoskeletal research laboratory.

Patients:

Thirteen subjects participated in joint position error tests and isokinetic concentric strength assessment in shoulder rotation, before and after rotator muscle fatigue.

Interventions:

Local muscle fatigue was induced using isokinetic concentric contractions of the shoulder rotator muscles.

Main Outcome Measurements:

Shoulder rotator strength and JPS error signals were measured before fatigue, immediately after fatigue, and every ten minutes thereafter for one hour.

Results:

Before shoulder rotation muscle fatigue, the accuracy of shoulder JPS was 2.79 ± 1.67 degrees. After muscle fatigue, the accuracy decreased to 6.39 ± 2.90 degrees. Shoulder JPS was influenced up to 40 minutes after muscle fatigue, but shoulder strength was only affected for 10 minutes after muscle fatigue.

Conclusions:

Proprioceptive recovery was slower than strength following fatigue of the shoulder rotators.

Scapulothoracic latent muscle reaction timing comparison between trained overhead throwers and untrained control subjects

AIM

This study evaluated select scapulothoracic muscles for training-induced latent muscle reaction timing (LMRT) changes. Comparisons were also made between the dominant and non-dominant upper extremities and between individual muscles.

MATERIALS AND METHODS

Fifteen male trained overhead throwers (college baseball pitchers) and 15 male untrained, age-matched control subjects participated in this study. Scapulothoracic muscle activation data were collected as subjects attempted to stop a variably timed, sudden glenohumeral joint internal rotation perturbation.

RESULTS

Training group differences were not evident for LMRT (P=0.56), however upper extremity dominance (P=0.003) and test muscle (P=0.0002) displayed significant differences. Dominant upper extremity upper trapezius muscle LMRT (72.5+/-26 ms) occurred later than non-dominant upper trapezius muscle LMRT (60.0+/-14.1 ms, P=0.001). Dominant upper extremity middle trapezius-rhomboid muscle LMRT (60.0+/-16.2 ms) occurred later than non-dominant middle trapezius-rhomboid muscle LMRT (50.2+/-12.6 ms, P=0.004). Dominant upper extremity upper trapezius muscle LMRT also occurred later than serratus anterior (55.7+/-16.0 ms, P=0.001) and middle trapezius-rhomboid LMRT (60.2+/-16 ms, P=0.003). Mean overall dominant upper extremity LMRT (62.7+/-19.4 ms) was delayed compared with mean overall non-dominant upper extremity LMRT (53.9+/-12.4 ms, P=0.003).

CLINICAL CONSEQUENCES

Although training was not found to influence scapulothoracic LMRT, differences were observed between the dominant and non-dominant upper extremities. Consistent LMRT delays at the dominant upper extremity suggest possible neuromuscular timing differences to enable prolonged glenohumeral joint and scapulothoracic articulation acceleration before deceleration through eccentric muscle activation. Both trained and untrained overhead throwers displayed this response. Variable perturbation test velocities, and in-season testing of larger subject groups may be needed to better elucidate the more subtle differences associated with training.

Sensorimotor contribution to shoulder stability: effect of injury and rehabilitation

Shoulder joint stability is the humeral head remaining or promptly returning to proper alignment within the glenoid fossa. This is mediated by both mechanical and dynamic restraint mechanisms. Coordination of these restraint systems is required for shoulder joint stability. The sensorimotor system is defined as all of the sensory, motor, and central integration and processing components involved in maintaining joint stability. The sensorimotor system is comprised of several components including proprioception, joint position sense, kinesthesia, sensation of force, and neuromuscular control. With joint injury, not only are the mechanical restraints disrupted (joint capsule, glenoid labrum, etc.) but also, the sensorimotor system is affected. Restoration of the sensorimotor system has been shown to occur through both surgical and conservative intervention and rehabilitation. Surgery has been shown to restore both mechanical restraints and the sensorimotor system. Specific rehabilitation techniques have also been effective at improving the sensorimotor system in healthy and pathological patients.

Kinematic and EMG characteristics of simple shoulder movements with proprioception and visual feedback

The objective of this study was to determine if simple, shoulder movements use the dual control hypothesis strategy, previously demonstrated with elbow movements, and to see if this strategy also applies in the absence of visual feedback. Twenty subjects were seated with their right arm abducted to 90 degrees and externally rotated in the scapular plane. Subjects internally rotated to a target position using a custom shoulder wheel at three different speeds with and without visual feedback. Kinematics were collected with a motion analysis system and electromyographic (EMG) recordings of the pectoralis major (PECT), infraspinatus (INFRA), anterior and posterior (ADELT, PDELT) deltoid muscles were used to evaluate muscle activity patterns during movements. Kinematics changed as movement speed increased with less accuracy (p<0.01). Greater EMG activity was observed in the PECT, PDELT, and INFRA with shorter durations for the ADELT, PDELT and INFRA. Movements with only kinesthetic feedback were less accurate (p<0.01) and performed faster (p<0.01) than movements with visual feedback. EMG activity suggests no major difference in CNS control strategies in movements with and without visual feedback. Greater resolution with visual feedback enables the implementation of a dual control strategy, allowing greater movement velocity while maintaining accuracy.

A comparison of individual joint contributions to multijoint position reproduction acuity in overhead-throwing athletes

BACKGROUND

Measures of joint position sense often test single-axis motions isolating a single joint. Such methods hamper our ability to apply findings to functional multijoint activities. Using a functional, active, multijoint test, we measured upper-extremity position reproduction in overhead-throwers. We compared acuity among four joints and examined individual joint contributions or patterns of contribution among joints to overall task acuity.

METHODS

We used an electromagnetic tracking device to measure reproduction of two functional upper-extremity positions. We calculated absolute, constant and variable error at four upper-extremity joints around multiple axes of rotation: three axes at the scapulothoracic and glenohumeral joints and two axes at the elbow and wrist. To represent individual joint acuity, we calculated 3-dimensional variable error. Additional 3-dimensional variable error scores using deviation in hand position (with reference to the thorax) represented overall task acuity. We used principle component analyses to identify contributions of individual joints or patterns of contribution among joints to overall task acuity for absolute, constant and variable error.

FINDINGS

Scapulothoracic and glenohumeral joints displayed better acuity compared with elbow and wrist joints. When examined separately, absolute, constant and variable error scores did not indicate any individual joint contributed more to task acuity. When we examined the principle components of all error score measures together, a distinct proximal-to-distal pattern of joint contribution to overall task acuity emerged.

INTERPRETATION

Proximal joints display better reposition acuity compared with distal joints, however proximal joints contribute more to acuity of the overall task. Our results indicate that upper-extremity joints do not function independently in repositioning tasks and measures of absolute, constant and variable errors combined over multiple joints may better represent upper-extremity function.

Effect of positioning and bracing on passive position sense of shoulder joint

OBJECTIVE

To examine the effects of positioning and sleeve type bracing on passive position sense of shoulder joints of healthy untrained subjects.

METHOD

A cross over study was carried out on 26 subjects (13 male, 13 female) with a proprioception measurement device. The selected method of testing was passive reproduction of a target angle. Both shoulder joints of all the subjects were evaluated with and without a compressive neoprene sleeve type of brace at two different start positions (45 degrees internal rotation, 75 degrees external rotation) with an angular rotational movement at a constant speed of 0.5 degrees /s. The angular displacements from the target angles at the end of the reproduction tests were recorded as position sense deficit scores.

RESULTS

The overall mean (SD) deficit score (0.99 (0.06)) was significantly (p<0.001) lower with the brace than without, and the overall mean deficit score was significantly (p<0.001) higher at the 45 degrees internal rotation start position than at the 75 degrees external rotation start position. However, there was no significant (p>0.05) interaction between brace application and start position.

CONCLUSION

Terminal limits of range of motion facilitate the position sense of shoulder joints. Compressive brace application improves the passive positioning sense possibly by stimulating cutaneous mechanoreceptors.

Measures of accuracy for active shoulder movements at 3 different speeds with kinesthetic and visual feedback

STUDY DESIGN

Repeated-measures experiment.

OBJECTIVE

To compare measures of end point accuracy (EPA) for 2 feedback conditions: (1) visual and kinesthetic feedback and (2) kinesthetic feedback alone, during shoulder movements, at 3 different speeds.

BACKGROUND

Shoulder joint kinesthesia is typically reported with EPA measures, such as constant error. Reporting multiple measures of EPA, such as variable error and absolute error, could provide a more detailed description of performance.

METHODS AND MEASURES

Subjects were seated with the shoulder abducted 90 degrees in the scapular plane and externally rotated 75 degrees, with the forearm placed in a custom shoulder wheel. Subjects internally rotated the shoulder 27 degrees to a target position at 48 degrees of shoulder external rotation for both conditions. Motion analysis was used to determine peak angular velocity and 3 EPA measures for shoulder movements. Each EPA measure was compared between the 2 feedback conditions and among the 3 speeds with a separate 2-way analysis of variance.

RESULTS

Movements performed with kinesthetic feedback alone, measured by constant error (P<.01), variable error (P<.01), and absolute error (P<.01), were less accurate than movements performed with visual and kinesthetic feedback. Faster movements were less accurate when measured by constant error (P = .01) and absolute error (P<.01) than slower movements. Subjects tended to overshoot the target in the absence of visual feedback; however, movement speed played minimal role in the overshooting.

CONCLUSIONS

Multiple measures of EPA, such as constant, variable, and absolute error during simple restricted shoulder movements may provide additional information regarding the evaluation of a motor performance or identify different central nervous system control mechanisms for joint kinesthesia.

Cryotherapy does not impair shoulder joint position sense11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors(s) or upon any organization with which the author(s) is/are associated

OBJECTIVE

To determine the effects of a cryotherapy treatment on shoulder proprioception.

DESIGN

Crossover design with repeated measures.

SETTING

University athletic training and sports medicine research laboratory.

PARTICIPANTS

Thirty healthy subjects (15 women, 15 men).

INTERVENTION

A 30-minute cryotherapy treatment.

MAIN OUTCOME MEASURES

Joint position sense was measured in the dominant shoulder by using an inclinometer before and after receiving 30 minutes of either no ice or a 1-kg ice bag application. Skin temperature was measured below the tip of the acromion process and recorded every 5 minutes for the entire 30 minutes and immediately after testing. Three different types of error scores were calculated for data analyses and used to determine proprioception.

RESULTS

Separate analyses of absolute, constant, and variable error failed to identify changes in shoulder joint proprioception as a function of the cryotherapy application.

CONCLUSIONS

Application of an ice bag to the shoulder does not impair joint position sense. The control of proprioception at the shoulder may be more complex than at other joints in the body. Clinical implications may involve modifying rehabilitation considerations when managing shoulder injuries.

Reflexive muscle activation alterations in shoulders with anterior glenohumeral instability

BACKGROUND

Patients with glenohumeral instability have proprioceptive deficits that are suggested to contribute to muscle activation alterations.

HYPOTHESIS

Muscle activation alterations will be present in shoulders with anterior glenohumeral instability.

STUDY DESIGN

Posttest-only control group design.

METHODS

Eleven patients diagnosed with anterior glenohumeral instability were matched with 11 control subjects. Each subject received an external humeral rotation apprehension perturbation while reflexive muscle activation characteristics were measured with indwelling electromyography and surface electromyography.

RESULTS

Patients with instability demonstrated suppressed pectoralis major and biceps brachii mean activation; increased peak activation of the subscapularis, supraspinatus, and infraspinatus; and a significantly slower biceps brachii reflex latency. Supraspinatus-subscapularis coactivation was significantly suppressed in the patients with instability as well.

CONCLUSIONS AND CLINICAL RELEVANCE

In addition to the capsuloligamentous deficiency and proprioceptive deficits present in anterior glenohumeral instability, muscle activation alterations are also present. The suppressed rotator cuff coactivation, slower biceps brachii activation, and decreased pectoralis major and biceps brachii mean activation may contribute to the recurrent instability episodes seen in this patient group. Clinicians can implement therapeutic exercises that address the suppressed muscles in patients opting for conservative management or rehabilitation before and after capsulorraphy procedures.

Pressure between the humeral head and the subscapularis tendon after the modified Boytchev procedure

The pressure between the humeral head and the subscapularis tendon was determined in 32 patients who had recurrent anterior shoulder dislocations. These patients' pressures were measured during a modified Boytchev procedure both before and after transposition of the conjoined tendon, and they were remeasured at the time of screw removal, performed at a mean of 13 months after the initial surgery. The mean clinical follow-up period was 31 months. A micro-tip catheter transducer was inserted into the glenohumeral joint between the humeral head and the subscapularis tendon. Pressures were measured at particular degrees of motion for two positions: passive external rotation of the arm at the side at 0 degrees, 15 degrees, 30 degrees, 45 degrees, and 60 degrees and passive external rotation at the 90 degrees abducted position at 0 degrees, 30 degrees, 60 degrees, and 90 degrees. The pressures were statistically significantly higher after the conjoined tendon transfer at all measured degrees of motion in the two positions. The pressures at the time of screw removal were not statistically significantly different from those seen after the tendon transfer during external rotation at 90 degrees of abduction. The modified Boytchev procedure increases the pressure between the humeral head and the subscapularis tendon. We suspect that this increased pressure increases proprioceptive stimuli in the subscapularis tendon and thus accelerates the protective reflex needed to prevent shoulder dislocation.