Sensorimotor Factors Affecting Outcome Following Shoulder Injury

Cross-Cultural Adaptation, Reliability, and Validity of the Greek Version of the Fremantle Shoulder Awareness Questionnaire (FreSHAQ-GR) in Patients with Chronic Shoulder Pain

Shoulder pain is one of the most common musculoskeletal pathologies. The association of shoulder pain with impaired proprioception and bodily self-awareness called for the cross-cultural adaptation of the Fremantle Shoulder Awareness Questionnaire (FreSHAQ) in Greek. The FreSHAQ is a relatively new self-assessment 9-item scale for impaired somatic awareness in patients with shoulder pain. The study included 100 participants (54 women) between 20 and 80 years old, with chronic shoulder pain (>3 months duration), able to comprehend and speak Greek, and recruited from three private physical therapy practices. The cross-cultural adaptation process was followed to develop the Greek version of the questionnaire (FreSHAQ-GR). Further testing for construct validity via exploratory factor analysis and correlational analysis with the Shoulder Pain and Disability Index (SPADI), the Quick Disabilities of Arm, Shoulder, and Hand (QuickDASH), the pain catastrophizing scale (PCS), a pain intensity visual analog scale (PI-VAS) in the last week, and the demographic characteristics followed. Test-retest reliability of the FreSHAQ-GR in a sub-sample of patients (n = 25) was tested upon repeated completion of the scale after a week and examined with the intraclass correlation coefficient (ICC2,1), the standard error of the measurement (SEM), and the minimum detectable change (MDC) indices. The internal consistency of the scale was also assessed. The factor analysis revealed that the scale comprised one factor relevant to shoulder awareness but with fewer items (first 6 items) than the original FreSHAQ. Additionally, the FreSHAQ-GR (both versions) demonstrated statistically significant correlations (Spearman's r) with participants' age (r = -0.31/-0.29, p < 0.002), the PI-VAS (r = 0.54/0.52, p < 0.001), the SPADI total score and both of its subscales (r = 0.39-0.45/0.34-0.39, p < 0.001), the QuickDASH (r = 0.37/0.34, p < 0.001), and the PCS (r = 0.50/0.40, p < 0.001). The questionnaire's internal consistency (Cronbach's α/McDonald's ω) was 0.833/0.827 for the 9-item and 0.871/0.867 for the 6-item FreSHAQ-GR. Test-retest reliability was excellent for both versions of the FreSHAQ-GR (ICC2,1(95% CI) = 0.97/0.98 (0.91-0.99/0.94-0.99), and with a low error margin (SEM = 1.31/0.94 and MDC95% = 3.63/2.61). Therefore, the FreSHAQ-GR (6-item version) possesses very good measurement properties and can be administered to Greek-speaking patients with chronic shoulder pain.

Shoulder Proprioception Following Reverse Total Shoulder Arthroplasty for Unreconstructable Upper Third Fractures of the Humerus: 2-Year Outcomes

Background

Proximal humerus fractures may be comminuted in the elderly or after injury with high-energy mechanisms. Reverse total shoulder arthroplasty that may affect shoulder proprioception (rTSA) has also begun to play a part in treating acute proximal humeral fractures. In this study, the authors aimed to evaluate joint position sense (JPS) after rTSA.

Methods

Humac Norm II isokinetic device was used to evaluate the joint position sense. A joint angle was determined and the ability of the patient to create the same value of the angle by the active movement was evaluated. The difference between the pre-determined angle and the patient's measured angle was recorded. For proprioceptive sense, the initial position was 0° and the determination position was 30°, 60°, and 90° for flexion and abduction, and 15° and 30° for internal rotation and external rotation.

Results

While both the mean Constant and ADLEIR scores did not differ between non-operated and operated sides, the mean proprioception differences in all flexion (30°, 60°, and 90°), abduction (30°, 60°, and 90°), internal rotation (15° and 30°), and external rotation (15° and 30°) were significantly higher in the operated side than that in non-operated side (p < 0.01 for each pairwise comparison).

Conclusion

Reverse total shoulder arthroplasty (rTSA) treatment, which has increasingly become a surgical option in un-reconstructable proximal humeral fractures has significant adverse effects on proprioception on the operated side and may pose a risk for long-term instability, premature loosening, and prosthesis mechanical complications, in this context, well-designed prospective controlled studies are required.

The acute effects of vibratory stimuli during exercise on the sensorimotor control of the shoulder complex: A pilot study

BACKGROUND

Functional stability of the shoulder requires a balance of active forces, passive forces, and control subsystems of the joint complex. Although whole-body vibration enhances shoulder muscle function and proprioception, the impact of vibration on the sensorimotor control of the shoulder joint remains unclear.

OBJECTIVE

To investigate the acute effect of vibratory stimuli on the sensorimotor control of the shoulder joint.

METHODS

Fifteen male participants (age, 22.7 ± 2.3 years) were included and performed the exercise in a modified push-up position with partial weight-bearing on a vibration platform with and without vibratory stimuli. The vibration protocol included six sets lasting for 30 s each with a 30-s rest between sets. The main outcome measures included the upper limb static stability test, Upper Quarter Y Balance Test (UQYBT), and electromyography data of the upper limb.

RESULTS

Vibratory stimuli resulted in an increased UQYBT score (all directions; P< 0.01) and infraspinatus, serratus anterior, and lower trapezius muscle activity (P< 0.05) between pre- and post-exercise versus the control condition. Stabilometric parameters showed no significant interaction between condition and time.

CONCLUSIONS

Vibratory stimuli could maximize training benefits while limiting injury risk for athletes. Our findings could guide the development of rehabilitation programs for patients with shoulder instability.

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.

Relationship of scapular dyskinesis with the pattern of activation of periescapular muscles during exercise

abstract The aim of the present study was to analyze the activation pattern of the serratus anterior (SA), upper trapezius (UT), and lower trapezius (LT) muscles during periscapular exercises in individuals with and without ED, and to identify which proposed exercise presents greater activation of the periscapular muscles. Fourteen women, aged between 18 and 30 years, participated in this study, divided into a control group (n = 8) and a dyskinesis group (n = 8). The determination of the presence of ED was performed according to the analysis of scapular movement during arm elevation, using the yes/no classification. To evaluate muscle activation, electromyography signals of the SA, UT, and LT muscles were collected during exercise. The exercise protocol was composed of three repetitions of the exercises: punch up, wall slide, and scaption. The results showed that the ED group showed less activation of the AS and TT than the control group. During the scaption and wall slide exercises, the DE group showed less activation of the AS in relation to those without DE. There was no difference in muscle activation between the exercises. That individuals with dyskinesis have less activation of the muscles that control scapular mechanics and that the type of exercise did not influence the activation of the periscapular muscles.

Center of pressure (COP) measurement in patients with confirmed successful outcomes following shoulder surgery show significant sensorimotor deficits

PURPOSE

To determine the sensorimotor and clinical function of patients with confirmed successful outcome after either undergoing acromioclavicular joint (ACJ) stabilization, Bankart repair (BR), or rotator cuff repair (RC), and to compare these measures to the contralateral, healthy side without history of previous injuries or surgeries of the upper extremity. It was hypothesized that patients of each interventional group would have inferior sensorimotor function of the shoulder joint compared to the contralateral, healthy side, while presenting with successful clinical and functional outcomes.

METHODS

Three intervention groups including ten patients who had confirmed successful clinical and functional outcomes after either undergoing ACJ stabilization, BR, or RC were evaluated postoperatively at an average follow-up of 31.7 ± 11.6 months. Additionally, a healthy control group (CG) of ten patients was included. Clinical outcomes were assessed using the Constant-Murley (CM) and American Shoulder and Elbow Surgeons (ASES) Score. Pain was evaluated using the visual analogue scale (VAS). Sensorimotor function was assessed by determining the center of pressure (COP) of the shoulder joint in a one-handed support task in supine position on a validated pressure plate.

RESULTS

Each interventional group demonstrated excellent clinical outcome scores including the CM Score (ACJ 83.3 ± 11.8; BR 89.0 ± 10.3; RC 81.4 ± 8.8), ASES Score (ACJ 95.5 ± 7.0; BR 92.5 ± 9.6; RC 96.5 ± 5.2), and VAS (ACJ 0.5 ± 0.9; BR 0.5 ± 0.8; RC 0.5 ± 0.8). Overall, the CG showed no significant side-to-side difference in COP, whereas the ACJ-group and the BR-group demonstrated significantly increased COP compared to the healthy side (ACJ 103 cm vs. 98 cm, p = 0.049; BR: 116 cm vs. 102 cm, p = 0.006). The RC-group revealed no significant side-to-side difference (120 cm vs. 108 cm, n.s.).

CONCLUSION

Centre of pressure measurement detected sensorimotor functional deficits following surgical treatment of the shoulder joint in patients with confirmed successful clinical and functional outcomes. This may indicate that specific postoperative training and rehabilitation protocols should be established for patients who underwent surgery of the upper extremity. These results underline that sensorimotor training should be an important component of postoperative rehabilitation and physiotherapeutic activities to improve postoperative function and joint control.

LEVEL OF EVIDENCE

IV.

Imaging of shoulder instability

The shoulder enjoys the widest range of motion of all the joints in the human body, therefore requires a delicate balance between stability and motility. The glenohumeral joint is inclined to fall into two main instability categories: macro and micro. Macroinstability can be traumatic or atraumatic, with anterior or posterior dislocation of the humeral head. Microinstability falls within the broader section of acquired instability in overstressed shoulder caused by repeated joint stress. Anterior traumatic instability is the most frequent entity and a relatively common injury in young and athletic population. While shoulder instability is a clinical diagnosis, imaging impacts the patient management by detailing the extent of injury, such as capsulo-labral-ligamentous tears, fracture, and/or dislocation, describing the predisposing anatomic conditions and guide the therapetic choice. The aim of this comprehensive review is to cover the imaging findings of shoulder instability by different imaging techniques.

Which muscle performance can be improved after arthroscopic Bankart repair?

BACKGROUND

There are no published reports available regarding neuromuscular control recovery in nonathletic patients after arthroscopic (A/S) Bankart repair. This study aimed to compare neuromuscular control and performance of the rotator cuff muscles between patients who underwent A/S Bankart repair and normal controls.

METHODS

In total, 32 nonathletic patients who underwent A/S Bankart repair were compared with 32 asymptomatic nonathletic volunteers. Neuromuscular control index (time to peak torque and acceleration time), muscle strength ratio, muscle strength, and muscle endurance of the internal rotators (IRs) and external rotators (ERs) were measured using an isokinetic device at an angular velocity of 180°/s, with 90° shoulder abduction.

RESULTS

The neuromuscular control indices of both IRs and ERs were significantly lower in patients who underwent A/S Bankart repair than in normal controls (time to peak torque, IRs: 1059 ± 143 ms vs. 679 ± 226 ms, P = .011; ERs: 595 ± 286 ms vs. 379 ± 123 ms, P = .044; acceleration time, IRs: 75 ± 16 ms vs. 62 ± 15 ms, P = .039, ERs: 70 ± 19 ms vs. 54 ± 18 ms, P = .047). Muscle endurance was significantly lower in patients who underwent A/S Bankart repair than in normal controls (IRs: 670 ± 1 J vs. 718 ± 2 J, P = .002, ERs: 422 ± 6 J vs. 501 ± 2 J, P = .044). The neuromuscular control index showed a significant negative correlation with muscle endurance for both IRs and ERs after the operation (IRs: r = -0.737, P = .003, ERs: r = -0.617, P = .019).

CONCLUSION

Compared with normal controls, patients who underwent A/S Bankart repair did not show complete recovery of neuromuscular control of IRs and ERs, although their muscle strength ratio and muscle strength had fully recovered.

Bilateral shoulder proprioception deficit in unilateral anterior shoulder instability

HYPOTHESIS AND BACKGROUND

Proprioception is an important element of shoulder dynamic stability. It has been shown to be affected in cases of capsular or labral injuries of the glenohumeral joint. Therefore, this study was conducted to investigate bilateral shoulder proprioception by active reproduction of joint position both in patients with post-traumatic recurrent unilateral shoulder instability and in normal healthy volunteers.

METHODS

We compared 41 patients, comprising 11 female and 30 male patients with an average age of 25.6 years (range, 18-39 years), with post-traumatic unilateral anterior shoulder instability with a control group of 27 healthy volunteers with no history of shoulder problems and with normal shoulder function during examination. All patients were examined using a high-accuracy computer-controlled electronic goniometer (Propriometer). The error of active reproduction of joint position (EARJP) was measured in abduction, flexion, external rotation, and internal rotation in both shoulders.

RESULTS

We observed a significant deficit in the EARJP in the unstable shoulders within the instability group. Surprisingly, similar results were recorded for the contralateral, unaffected shoulders within this group of patients compared with the control group. Joint acuity increased with higher elevation of the arm position.

CONCLUSION

Unilateral shoulder injuries, resulting in instability, affect proprioception in both shoulders, as demonstrated by an increased EARJP. This is the first report of unilateral shoulder instability coexisting with inferior proprioception in both shoulders.

Immediate effect of scapula-focused exercises performed with kinematic biofeedback on scapular kinematics in individuals with subacromial pain syndrome

BACKGROUND

Given the changes in the patterns of muscular activation and scapular movement in individuals with subacromial pain syndrome, the use of neuromuscular training has been considered in rehabilitation protocols. There is currently no evidence of the effects of the use of three-dimensional (3D) kinematic biofeedback on individuals with subacromial pain syndrome. This study aimed to determine the immediate effect of scapular motor control exercises using 3D kinematic biofeedback on the scapular kinematics, inter-segment coordination and pain of individuals with subacromial pain syndrome.

METHOD

The kinematics of the scapulothoracic joint of 26 subjects with subacromial pain syndrome were assessed in the movement arm elevation and lowering in the sagittal plane before and after performance of three scapula-focused exercises using kinematic biofeedback. The individuals were familiarized with the selected exercises to acquire a greater scapular posterior tilt, while kinematic biofeedback, with visual and auditory stimuli, was used in real time. Scapular kinematics, pain, and subjective perception of exertion were the pre- and post-test measures.

FINDINGS

In the movement of arm elevation and lowering, no differences were found in scapular tilt and on coordination between the segments pre- and post-test and the effect size was considered small.

INTERPRETATION

Our results demonstrate that the performance of scapula-focused exercises using kinematic biofeedback does not cause immediate changes in the magnitude of scapular movement. However, inter-segmental coordination showed evidence of changes for scapular tilt in the lowering of the arm and internal rotation in the elevation and the lowering of the arm in individuals with subacromial pain syndrome.

Sensorimotor Control of the Shoulder in Professional Volleyball Players With Isolated Infraspinatus Muscle Atrophy

CONTEXT

Isolated infraspinatus muscle atrophy (IIMA) affects only the hitting shoulder of overhead-activity athletes and is caused by suprascapular nerve neuropathy. No study has assessed the static and dynamic stability of the shoulder in overhead professional athletes with IIMA to reveal possible shoulder sensorimotor alterations.

OBJECTIVE

To assess the shoulder static stability, dynamic stability, and strength in professional volleyball players with IIMA and in healthy control players.

DESIGN

Cross-sectional study.

SETTING

Research lab.

PATIENTS OR OTHER PARTICIPANTS

A total of 24 male professional volleyball players (12 players with diagnosed IIMA and 12 healthy players) recruited from local volleyball teams.

INTERVENTION(S)

Static stability was evaluated with 2 independent force platforms, and dynamic stability was assessed with the "Upper Quarter Y Balance Test."

MAIN OUTCOME MEASURE(S)

The static stability assessment was conducted in different support (single hand and both hands) and vision (open and closed eyes) conditions. Data from each test were analyzed with analysis of variance and paired t-test models to highlight statistical differences within and between groups.

RESULTS

In addition to reduced abduction and external rotation strength, athletes with IIMA consistently demonstrated significant less static (P < .001) and dynamic stability (P < .001), compared with the contralateral shoulder and with healthy athletes. Closed eyes condition significantly enhanced the static stability deficit of the shoulder with IIMA (P = .04 and P = .03 for both hand and single hand support, respectively) but had no effect on healthy contralateral and healthy players' shoulders.

CONCLUSIONS

This study highlights an impairment of the sensorimotor control system of the shoulder with IIMA, which likely results from both proprioceptive and strength deficits. This condition could yield subtle alteration in the functional use of the shoulder and predispose it to acute or overuse injuries. The results of this study may help athletic trainers and physical/physiotherapists to prevent shoulder injuries and create to specific proprioceptive and neuromuscular training programs.

Scapular-focused exercise treatment protocol for shoulder impingement symptoms: Three-dimensional scapular kinematics analysis

BACKGROUND

The present study aimed to describe the effects of a periscapular strengthening and neuromuscular training protocol in three-dimensional scapular kinematics and resting positioning in participants with shoulder impingement symptoms. Self-reported function was also evaluated.

METHOD

The study group comprised 50 subjects with shoulder impingement syndrome (control group, n=25; treatment group, n=25). The treatment group underwent 8weeks of neuromuscular training and periscapular strengthening. Scapular kinematics was measured using an electromagnetic tracking device, and the Brazilian version of the Shoulder Pain and Disability Index (SPADI-Br) questionnaire was carried out before and after the treatment.

FINDINGS

In the resting position, treated subjects had lower (p<0.01) internal rotation of the scapula compared to the control group, with a large effect size (2.4). On the coronal plane, the treated group had less scapular upward rotation (p<0.01) and less internal rotation (p<0.05), with a medium effect size. On the sagittal plane, the treated group had less internal rotation (p<0.01), less upward rotation (p<0.05), and less scapular anterior tilt (p<0.01), with a medium effect size. On the scapular plane, a reduction in upward rotation (p<0.01) after the intervention was observed, with a large effect size. Moreover, a reduction in the total SPADI-Br score was found, with a mean difference of 32.4 [24.4; 40.4] points (p<0.01) after the implementation of the protocol and a large effect size (2.0).

INTERPRETATION

The results provide biomechanical support for the clinical rationale for indicating therapeutic exercises focused on the periscapular muscles to improve scapular dynamics.

Reproducibility and validity of the Nintendo Wii Balance Board for measuring shoulder sensorimotor control in prone lying

INTRODUCTION

For the lower limbs, the Nintendo Wii Balance Board (NWBB) has been widely used to measure postural control. However, this has not been performed for upper limb measurements. Further, the NWBB has shown to produce more background noise with decreasing loads, which may be of concern when used for upper limb testing. The aim was to investigate reproducibility and validity of the NWBB.

METHODS

A test-retest design was performed with 68 subjects completing three different prone lying, upper limb weight-bearing balance tasks on a NWBB: two-arms, eyes closed (1) one-arm, non-dominant/non-injured (2) and one-arm, dominant/injured (3). Each task was repeated three times over the course of two test sessions with a 30-min break in between. Further, the level of background noise from a NWBB was compared with a force platform through systematic loading of both boards with increasing deadweights ranging from 5 to 90kg.

RESULTS

Test-retest reproducibility was high with ICCs ranging from 0.95 to 0.97 (95% CI 0.92 to 0.98). However, systematic bias and tendencies for funnel effects in the Bland Altman plots for both one-armed tests were present. The concurrent validity of the NWBB was low (CCC 0.17 (95% CI 0.12-0.22)) due to large differences between the NWBB and force platform in noise sensitivity at low deadweights (especially below 50kg).

CONCLUSION

The NWBB prone lying, shoulder sensorimotor control test was highly reproducible. Though, concurrent validity of the NWBB was poor compared to a force platform. Further investigation of the impact of the background noise, especially at low loads, is needed.

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.

Sensorimotor control deficiency in recurrent anterior shoulder instability assessed with a stabilometric force platform

BACKGROUND

Deficiencies in both afferent proprioceptive information and efferent motor responses have been independently reported in patients with recurrent anterior shoulder instability. We used a validated force platform method to analyze the association between the stabilometric parameters of the upper limb as representative of the shoulder's sensorimotor control and clinical glenohumeral joint instability.

METHODS

We enrolled 32 patients with unilateral recurrent anterior post-traumatic shoulder dislocation, on the dominant side in 13 patients (DIG) and the non-dominant side in 19 patients (NDIG) and 16 healthy nonathletic subjects (CG). Displacements of the Center of Pressure were measured by a Win-Posturo Medicapteurs force platform in the upper limb weight-bearing position with the lower limbs resting on a table up to the anterior superior iliac spines. The association between stabilometric values and clinical shoulder instability was analyzed by side-to-side comparisons and comparisons to a control group.

RESULTS

For CG and NDIG, there were no side-to-side differences. For DIG, stabilometric values were significantly higher on the dominant pathological shoulder side than on the healthy contralateral non-dominant side (P < .01). The percentage of side-to-side differences was higher in DIG than CG (P < .01).

CONCLUSION

Sensorimotor control deficiency was associated with recurrent anterior shoulder instability, especially in patients with the pathological shoulder on their dominant side. Using a force platform to assess sensorimotor control of the shoulder is feasible in patients with shoulder instability, and can allow assessment of the global sensorimotor control deficiency present in unstable shoulders.

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.

Kinaesthesia and Methods for its Assessment: Literature Review

In this review measurement techniques used for kinaesthetic sense assessment are presented. Kinaesthesia is an important part of human movement control and provides us with better understanding of specific movement system adaptations to fatigue, training and injury. Additionally, decreased kinaesthesia can be an injury predisposing factor, which stresses the necessity for its assessment in sports injury prevention programs. First, terminology and functional concept of kinaesthesia is presented in relation to other related concepts like proprioception and sensory-motor function. For better understanding, basic underlying neurological backgrounds are discussed in chapter two, encompassing peripheral sensory fields as well as the basics of the central processing. Additionally, factors affecting kinaesthesia and its adaptations to training are presented. Functional aspects are discussed, supporting the role of assessment of kinaesthesia in sports and rehabilitation. In the third chapter, a proposal for measuring methods classification is given. In the final chapter, different measuring protocols and their modifications are presented. Due to their usefulness in sports and injury prevention, methods for measuring sense of joint position, movement onset and active tracking are discussed in more detail. Possibilities and examples of their application to sports and sports injury rehabilitation settings are presented. Some basic guidelines are given of how to use these methods in training or for screening kinaesthesia.