Lower leg muscle activation during the ebbets foot drills.

Lateral ankle sprains (LAS) often lead to chronic ankle instability (CAI). The Ebbets foot drills were created to strengthen the lower leg muscles and reduce the risk of LAS. The current study aimed to explore the activation of the lower leg muscles during the Ebbets foot drills. Twenty-two (22) college students without LAS participated in the study. Surface electromyography (sEMG) of the tibialis anterior (TA), tibialis posterior (TP), and peroneus longus (PL) was collected during each of the Ebbets foot drills and a normal walking trial. The sEMG mean root mean square (RMS) was calculated for each walking and Ebbets foot drill trial duration. The mean RMS was higher during the Ebbets foot drills compared to normal walking for all muscles. The TA sEMG mean RMS was greater (4.0-68.3%, P = 0.001-0.023) during all the Ebbets foot drills than during the walking trial. The TP had greater mean RMS during the toe-in (50.4%, P < 0.001), toe-out (55.0%, P < 0.001), and backward walking (47.3%, P < 0.001) drills, than during the walking trial. The PL had greater mean RMS during all Ebbets foot drills (19.4-53.7%, P < 0.001) except for the heel walking and inversion drills. Ebbets foot drills higher muscle activity than regular walking, suggesting that the Ebbets foot drills could aid in the strengthening of the TA, TP, and PL muscles. These results build evidence on Ebbets' theory and indicate that these drills may be used to rehabilitate LAS and CAI.

Youth throwing athletes do not show bilateral differences in medial elbow width or flexor tendon thickness.

BACKGROUND: Medial elbow laxity develops in throwing athletes due to valgus forces. Medial elbow instability in professional, collegiate, and high school athletes is well documented; however, the medial elbow of young throwing athletes has received less attention. This study investigated the medial elbow and common flexor tendon during applied elbow valgus stress of youth baseball players. METHODS: The study included 15 participants. The medial elbow width and thickness of the common flexor tendon were measured on ultrasound images. RESULTS: No significant side differences in medial elbow width or common flexor tendon were found at rest or under applied valgus stress. At rest, the medial elbow joint width was 3.34±0.94 mm on the dominant side and 3.42±0.86 mm on the non-dominant side. The dominant side increased to 3.83±1.02 mm with applied valgus stress, and the non-dominant side increased to 3.96±1.04 mm. The mean flexor tendon thickness was 3.89±0.63 mm on the dominant side and 4.02±0.70 mm on the non-dominant side. CONCLUSIONS: These findings differ from similar studies in older throwing athletes, likely because of the lack of accumulated stress on the medial elbow of youth throwing athletes. Maintaining elbow stability in young throwing athletes is a vital step to preventing injury later in their careers.

Serratus Anterior Fatigue Reduces Scapular Posterior Tilt and External Rotation During Arm Elevation.

CONTEXT: Fatigue of the scapular stabilizing muscles resulting from repeated arm motion has been reported to alter scapular kinematics, which could result in shoulder pathology, especially impingement. OBJECTIVE: This study aimed to examine the effects of fatigue of the serratus anterior muscle on scapular kinematics, specifically, decrease scapular posterior tilt and upward scapular rotation during arm elevation. DESIGN: Repeated measures. SETTING: Laboratory. PARTICIPANTS: Thirty participants were included in the investigation. INTERVENTIONS: Scapular kinematics and shoulder strength were measured before and immediately following a serratus anterior fatigue protocol. MAIN OUTCOME: Scapular 3-dimensional position during arm elevation. RESULTS: No difference in upward rotation of the scapula between prefatigue and postfatigue conditions (ascending: P = .188; descending: P = .798). Scapular posterior tilt decreased during arm elevation following the fatigue protocol between 60° and 90° and 90° and 120° of arm elevation during the ascent (P = .004) and the descent (P = .013). Fatigue by arm elevation angle interaction was found for clavicular elevation during the ascent (P = .050) between 90° and 120° of arm elevation. Scapular internal rotation increased during the ascent (P = .027). There was no difference in clavicular protraction between the prefatigue and postfatigue conditions (ascending: P ≤ .001; descending: P ≤ .001). CONCLUSION: Fatigue of the serratus anterior decreases posterior scapular tilt and greater clavicular elevation and scapular internal rotation at higher arm elevation angles. These findings are consistent with the scapular kinematic patterns associated with shoulder pain. Improving serratus anterior endurance might delay the changes in scapular kinematics associated with repeated arm motion and shoulder injury mechanisms.

Musculoskeletal Injury in Reserve Officers' Training Corps: A Report From the Athletic Training Practice-Based Research Network.

BACKGROUND: Reserve Officers' Training Corps (ROTC) cadets must meet the same physical standards as active duty military servicemembers and undergo organized physical training (PT). ROTC participation, like all physical activity, can result in training-related musculoskeletal injury (MSKI), and of course, cadets could sustain MSKI outside of ROTC. However, MSKI incidence in ROTC programs is largely unknown. PURPOSE: To describe patient and injury demographics of MSKI in 5 universities' Army ROTC programs. STUDY DESIGN: Descriptive epidemiology study. METHODS: A retrospective chart review of electronic medical records was performed using the Athletic Training Practice-Based Research Network (AT-PBRN). Athletic trainers at 5 clinical practice sites within the AT-PBRN documented injury assessments via a web-based electronic medical record system. Medical records during the 2017-2018 and 2018-2019 academic years were used for analysis. Summary statistics were calculated for age, sex, height, body mass, military science year, training ability group, mechanism of injury, activity type associated with injury, anatomic location of injury, participation status, injury severity, and diagnosis. RESULTS: A total of 364 unique injuries were documented. Cadets in the most advanced fitness group (Alpha; n = 148/364) and in their third year of training (n = 97/364) presented with the most injuries. Injuries most commonly occurred during PT (n = 165/364). Insidious onset (n = 146/364) and noncontact (n = 115/364) mechanisms of injury were prevalent. The most frequent anatomic location of injury was the knee (n = 71/364) followed by the ankle (n = 57/364). General sprain/strain was the most frequent International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code reported (n = 34/364). CONCLUSION: The knee was the most frequent location of MSKI in ROTC participants, and most MSKIs had insidious onset. Cadets with higher injury frequency were high achieving (Alpha) and in a critical time point in ROTC (military science year 3). The majority of MSKIs can be attributed to ROTC training, with PT being the most frequent activity associated with injury. Civilian health care providers, from whom ROTC cadets will most likely seek medical attention, need to be aware of ROTC physical demands as well as the characteristics of training-related injuries.

Musicians Have Thicker Median Nerve Cross Sectional Area and More Symptoms of Carpal Tunnel Than Non-Musicians.

AIMS: Musicians spend numerous hours perfecting their skills and art, often leading to overuse injuries of the hand; of specific concern to musicians is carpal tunnel syndrome (CTS). This study evaluated the median nerve cross-sectional area and hand function of musicians and made comparisons to non-musicians. METHODS: Seventy-six participants took part in the study, 38 music students and professors in the musician group and 38 participants in the control group. Participants completed patient-reported questionnaires to assess the level of pain and hand function. Ultrasound images were collected at the carpal tunnel inlet and outlet. The median nerve cross-sectional area and the depth of the carpal tunnel were measured on ultrasound images using software imbedded in the ultrasound unit. RESULTS: Musicians showed higher levels of hand dysfunction and CTS symptoms than the non-musicians. The median nerve cross-sectional area was greater in musicians than in the non-musician group on both the right (mean difference 1.5 mm2, p=0.002) and left sides (mean difference 0.9 mm2, p=0.036). The depth of the carpal tunnel at the carpal tunnel inlet and outlet did not differ between the groups (p>0.05). CONCLUSION: The current research identified between-group differences in median nerve cross-sectional area and the level of hand dysfunction. Understanding the interaction between the anatomy of the wrist and wrist and hand dysfunction will benefit clinicians when evaluating and treating musicians.

The Effect of Repeated Shoulder Motion on Scapular Dyskinesis in Army ROTC Cadets.

INTRODUCTION: Altered or abnormal scapular motion has been associated with increased shoulder pain and dysfunction. Fatigue of the scapular stabilizing muscles resulting from repeated arm motion has been reported to alter scapular kinematics, which could result in the clinical assessment of scapular dyskinesis. The purpose of this study was to characterize the effect of repeated arm motion on the development of scapular dyskinesis. The hypothesis was that repeated arm motion will induce a subtle or obvious scapular dyskinesis. MATERIALS AND METHODS: About 30 army Reserve Officer Training Corps (ROTC) cadets participated in the research study. The cadets level of shoulder function was determined using the Quick Disabilities of the Arm Shoulder and Hand and Pennsylvania Shoulder Score shoulder scores. Cadets performed an exercise protocol of 30 repetitions of weighted shoulder motion in the frontal plane. Shoulder and scapular musculature strength measurements were recorded prior to and immediately following the exercise protocol using hand-held dynamometry. The scapular dyskinesis test was performed prior to the exercise protocol and during the last five repetitions of the exercise protocol. RESULTS: Prior to the exercise, protocol 3/30 were categorized with scapular dyskinesis on the left side and 3/30 were categorized with scapular dyskinesis on their right side. Following the exercise, protocol 8/30 were categorized with left-side scapular dyskinesis (χ2 = 9.167, P = 0.002) and 6/30 with right-side dyskinesis (χ2 = 4.537, P = 0.033). Shoulder strength decreased following the exercise protocol for all participants. The participants that developed scapular dyskinesis were weaker than those with normal scapular motion. However, the difference did not reach statistical significance. Participants graded with obvious scapular dyskinesis following the exercise protocol reported higher Quick Disabilities of the Arm Shoulder and Hand scores (P = 0.04) and lower scores on the Pennsylvania Shoulder Score (P = 0.005). CONCLUSIONS: Repeated shoulder motion increased the frequency of scapular dyskinesis in army ROTC cadets. The cadets that developed scapular dyskinesis also reported greater disability and lower function of the upper extremity. The results provide a link between scapular dyskinesis, upper extremity function, and the strength of the scapular stabilizing muscles. Improving the strength of the scapular stabilizing musculature might reduce the effects of repeated arm motions.

Wrist Flexion Exercise Increases the Width of the Medial Elbow Joint Space During a Valgus Stress Test.

OBJECTIVES: The medial elbow is stabilized during valgus loading by the ulnar collateral ligament, the flexor pronator mass (FPM), and the radial head. Impairment of the FPM can occur as a result of repeated wrist flexion activity. The purpose of this study was to determine the effect of repeated elbow flexion exercise on medial elbow stability. METHODS: Thirty volunteers were included in this study. Ultrasound images of the medial joint space of the nondominant elbow of the participants were collected during a valgus stress test. The images were collected before and immediately after a wrist flexion exercise protocol. RESULTS: The wrist flexion strength measure decreased (7.5%) after the exercise protocol (t = 3.840; P = .001). The medial elbow width increased between unstressed (mean ± SD, 2.8 ± 0.1 mm) and stressed (3.6 ± 0.1 mm) conditions (P < .001). The stress-by-fatigue interaction was significant (P = .048). The medial elbow width increased after fatigue (0.9 ± 0.09 mm) while remaining unchanged in the unstressed condition. CONCLUSIONS: This study found an effect of repeated wrist flexion exercise on decreasing the stability of the medial elbow. Future research needs to explore the mechanisms leading to the decrease in medial elbow stability and to identify the effect of FPM fatigue on the development of medial elbow pain associated with activities.

Ultrasound-Assisted Assessment of Medial Elbow Stability.

OBJECTIVES: An assessment of medial elbow stability is essential to the patient with an ulnar collateral ligament injury. Ultrasound imaging can be used to assess medial elbow stability. This study determined the effect of the elbow flexion angle on the medial elbow joint space during clinical tests of medial elbow stability. METHODS: Ultrasound images of the nondominant elbow were collected during 3 tests of medial elbow stability: valgus stress test, weighted valgus test, and milking maneuver. The elbow flexion angle increased between the valgus stress test and milking maneuver. The width of the medial joint space was measured on ultrasound images collected in unstressed and stressed conditions. RESULTS: Across test conditions, the medial joint width was greater in the stressed condition (mean ± SD, 3.7 ± 0.1 mm) than in the unstressed condition (2.9 ± 0.09 mm). The medial elbow joint space width was less (mean difference, 0.16 ± 0.01 mm; P = .01) in the milking maneuver position compared to the valgus stress test positions. CONCLUSIONS: This study provides evidence that changes in the width of the medial elbow during clinical evaluation of the unimpaired elbow can be detected by ultrasound. Changing the elbow flexion angle did not affect the change in width of the medial elbow during valgus loading.

Effect of Arm Position on Width of the Subacromial Space of Upper String Musicians.

OBJECTIVE: Musicians often end their musical career due to musculoskeletal injury. A leading source of shoulder pain in upper string musicians is rotator cuff disease (RCD). Multiple factors contribute to its development. Compressive overload of the soft tissues of the subacromial space resulting from a decrease in the width of the subacromial space has been identified as an extrinsic factor contributing to RCD development. The purpose of this study was to characterize the width of the subacromial space by measuring acromial-humeral distance (AHD) of upper string musicians, while their arms are in standard playing positions. METHODS: Experienced musicians (n=23) were recruited from local communities. Shoulder ultrasound images were collected using standard imaging techniques. Images were collected and the AHD measured while the musician's arm was in positions associated with playing the violin. RESULTS: On the right side, the arm position main effect was significant (p<0.001): the AHD in the 4th string position (8.8±1.9 mm) was less than the 1st string (11.3±1.4 mm) and resting (11.7±1.3 mm) positions. There was no difference in AHD between resting (10.0±5.8 mm) and instrument-support positions (10.6±1.5 mm). The resting AHD was smaller (p=0.04) on the right side compared to the left (12.2±1.4 mm). There was not statistically significant difference (p=0.138) in the occupation ratio (supraspinatus tendon thickness/AHD) between the right (mean 0.543±0.80 mm) and left sides (mean 0.510±0.087 mm). CONCLUSIONS: The AHD measurement decreased in the playing positions compared to resting positions. Treatment interventions that help musicians maximize the width of their subacromial space might help reduce the prevalence of shoulder pain in this population.

Full can test: Mechanisms of a positive test in patients with shoulder pain.

BACKGROUND: The full can test is theorized to produce compressive loads on the supraspinatus tendon within the subacromial space. Characterizing the width of the subacromial outlet, scapular orientation, and shoulder pain during the full can test will improve the mechanistic understanding of the positive full can test. METHODS: Cross-sectional repeated measures design. Participants with subacromial pain syndrome (n=30) were compared to a matched control group (n=30) during 2 conditions: passive support, and the full can test. The full can test was performed with the arm elevated to 90° in the scapular plane. In both conditions, measurements were taken of acromiohumeral distance with ultrasonography, scapular position using electromagnetic tracking, shoulder strength using a dynamometer, and shoulder pain with the 11-point rating scale. FINDINGS: During the full can test, both groups had a decreased acromial humeral distance, scapular upward rotation, posterior tilt, external rotation and clavicular protraction as compared to passive support (p<0.05). The subacromial pain group as compared to the control group reported greater shoulder pain (p<0.001), reduced strength (p=0.002) and greater scapular anterior tilt (p<0.05) during the full can test. INTERPRETATION: This study indicates the mechanisms of a full can test are a reduction in the acromial humeral distance, accompanied by scapular kinematic changes. A positive test of increased pain and reduced strength in those with subacromial pain syndrome can be explained additionally by an increase in scapular anterior tilt. These mechanistic changes may lead to tendon compression, but this cannot be verified as direct tendon compression was not measured.

Relative scapular muscle activity ratios are altered in subacromial pain syndrome.

BACKGROUND: Coordinated muscle activity is needed for synchronized joint motion and stability. Characterizing relative scapular muscle activity deficits in participants with shoulder pain will provide foundational knowledge to develop rehabilitation programs. METHODS: Participants were recruited with subacromial pain syndrome and an asymptomatic control group matched for age, gender, and dominant arm (N = 56). Surface electromyographic muscle activity was recorded from the upper, middle, and lower trapezius (UT, MT, LT) and serratus anterior (SA) during 5 repetitions of a weighted arm elevation task. Muscle activity was normalized to a reference contraction and then expressed as UT/MT, UT/LT, UT/SA, and LT/SA ratios. Ratios were compared between groups and across 3 arm angle intervals during ascending and descending elevation. RESULTS: A 2 × 3 mixed-model analysis of variance yielded a group main effect for the UT/LT ratio, with a higher ratio in the subacromial pain group during ascending (mean difference, 0.92; P = .008) and descending (mean difference, 0.70; P = .030). For the LT/SA ratio, there was a group effect: a lower ratio in the subacromial group during ascending (mean difference, -0.25; P = .026) and descending (mean difference, -0.51; P = .032). There were no differences for the UT/MT or UT/SA. DISCUSSION: There is a disruption in coordination between the LT and SA and the UT and LT during an arm elevation task in patients with subacromial pain syndrome. The LT was part of both altered ratios, indicating the relative importance of the LT. Future research should determine if exercises aimed at restoring the dysfunctional LT/SA and UT/LT force couples are beneficial to reduce shoulder pain and disability in patients with unilateral shoulder pain.

Electrical stimulation and blood flow restriction increase wrist extensor cross-sectional area and flow meditated dilatation following spinal cord injury.

PURPOSE: To examine the effects of neuromuscular electrical stimulation (NMES) and blood flow restricted (BFR) exercise on wrist extensors cross-sectional area (CSA), torque and hand functions compared NMES only in individuals with incomplete tetraplegia. The acute effect of an acute bout of NMES with BFR on flow mediated dilation (FMD) was compared with BFR only. METHOD: Nine men completed 6 weeks twice weekly of bilateral NMES training of the wrist extensor muscles. The right forearm received NMES + BFR (30 % above the resting systolic blood pressure), while the left forearm received NMES only. The CSA of the extensor carpi radialis longus (ECRL) and extensor digitorum communis (EDC) muscles was measured on ultrasound images. Torque was measured isometrically and hand function with grasp and release test. Another eight men with SCI received NMES+BFR to the right forearm, while the left forearm received BFR only. Immediately, the FMD of the brachial artery was measured. RESULT: Following training, the ECRL CSA was 17 % greater in the NMES+BFR forearm (mean difference = 0.6 cm(2), p = 0.003) compared with the NMES only. The NMES+BFR had a 15 % increase in ECRL CSA (mean increase = 0.58 cm(2), p = 0.048). FMD increased (p = 0.05) in the exercise arm (12 ± 3 %) compared with the control arm (6.5 ± 6 %). CONCLUSION: NMES training with BFR is a strategy that can increase skeletal muscle size. NMES with and without BFR can improve wrist strength and hand function. The acute effects of NMES+BFR may suggest that an increase in FMD may partially contribute to skeletal muscle hypertrophy.

Empty can exercise provokes more pain and has undesirable biomechanics compared with the full can exercise.

BACKGROUND: The purpose of this investigation was to characterize the scapular position and scapular muscle activation during the empty can (EC) and full can (FC) exercises. The EC exercise has been shown to produce scapular kinematics associated with the mechanism leading to subacromial impingement syndrome (SAIS) but has not been investigated in patients with (SAIS). This investigation will help improve the treatment of patients with SAIS. METHODS: Participants with SAIS (n = 28) performed 5 consecutive repetitions of FC and EC exercises. Scapular and clavicular 3-dimensional positions and scapular muscle activity were measured during each exercise. Pain was measured with the numeric pain rating 11-point scale. RESULTS: Participants reported greater pain during the EC exercise vs the FC exercise (difference, 1; P = .003). During the EC exercise, participants were in greater scapular upward rotation (difference, 3°; P < .001), internal rotation (mean difference, 2°; P = .017), and clavicular elevation (difference, 3°, P < .001) and in less scapular posterior tilt (difference, 2°; P < .001). There was greater activity of upper trapezius (difference, 4%, P = .002), middle trapezius (difference, 3%; P < .001), and serratus anterior (difference, 0.5%; P = .035) during ascent, and during the descent of greater upper trapezius (difference, 2%, P = .005), and middle trapezius (difference, 1%; P = .003), but less activity of the lower trapezius (difference, 1%; P = .039). CONCLUSIONS: The EC exercise was associated with more pain and scapular positions that have been reported to decrease the subacromial space. Scapular muscle activity was generally higher with the EC, which may be an attempt to control the impingement-related scapular motion. The FC exercise of elevation is preferred over the EC exercise.

Biomechanical measures in participants with shoulder pain: Intra-rater reliability.

Biomechanical measures are used to characterize the mechanisms of treatment for shoulder pain. The objective was to characterize test-retest reliability and measurement error of shoulder surface electromyographic(sEMG) and kinematic measures. Individuals(n = 12) with subacromial pain syndrome were tested at 2 visits. Five repetitions of shoulder scapular plane elevation were performed while collecting sEMG of the upper trapezius(UT), middle trapezius(MT), lower trapezius(LT), serratus anterior(SA) middle-deltoid, and infraspinatus muscles during ascending and descending phases. Simultaneously, electromagnetic sensors measured 3-dimensional kinematics of scapular internal/external rotation, upward/downward rotation, posterior/anterior tilt, and clavicular elevation/depression and clavicular protraction/retraction. Kinematic and sEMG variables were reduced for the total phase of ascending and descending elevation (30°-120°, 120°-30°), at 30° intervals for sEMG, and at every 30° discrete kinematic angle. The intraclass correlation coefficients(ICC) ranged from 0.08 to 0.99 for sEMG and 0.23-0.95 for kinematics. Correspondingly, the standard error of the measurement(SEM) and minimal detectable change(MDC) for sEMG measures varied from 2.3% to 103.8% of a reference contraction(REF-contraction). For kinematics, the SEM and MDC varied from 1.4° to 5.9°. Between-day reliability was good to very good, except for scapular internal/external rotation kinematics, and sEMG for the LT, UT, and SA. sEMG error values were highest (>25%REF-contraction) for most of the LT, UT, and SA variables. Kinematic error values indicate changes or differences of 2°-3° are meaningful, except for upward/downward rotation and internal/external rotation with MDCs of 4°-6°. Generally, data from the total phase of movement had better reliability and lower error than the data from sEMG interval or kinematic discrete angles.

Visual scapular dyskinesis: kinematics and muscle activity alterations in patients with subacromial impingement syndrome.

OBJECTIVE: To characterize scapular kinematics and shoulder muscle activity in patients with subacromial impingement syndrome, with and without visually identified scapular dyskinesis. DESIGN: Cross-sectional study. SETTING: Laboratory. PARTICIPANTS: Participants with subacromial impingement syndrome (N=38) were visually classified using a scapular dyskinesis test with obvious scapular dyskinesis (n=19) or normal scapular motion (n=19). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: An electromagnetic motion capture system measured 3-dimensional kinematics of the thorax, humerus, and scapula. Simultaneously, surface electromyography was used to measure muscle activity of the upper, middle, and lower trapezius; serratus anterior; and infraspinatus during ascending and descending phases of weighted shoulder flexion. Separate mixed-model analyses of variance for the ascending and descending phases of shoulder flexion compared kinematics and muscle activity between the 2 groups. Shoulder disability was assessed with the Pennsylvania Shoulder Score (Penn). RESULTS: The group with obvious dyskinesis reported 6 points lower on Penn shoulder function (0-60 points), exhibited a main group effect of less scapular external rotation of 2.1° during ascent and 2.5° during descent, and had 12.0% higher upper trapezius muscle activity during ascent in the 30° to 60° interval. CONCLUSIONS: Patients with obvious dyskinesis and subacromial impingement syndrome have reduced scapular external rotation and increased upper trapezius muscle activity, along with a greater loss of shoulder function compared with those without dyskinesis. These biomechanical alterations can lead to or be caused by scapular dyskinesis. Future studies should determine if correction of these deficits will eliminate scapular dyskinesis and improve patient-rated shoulder use.

Supraspinatus tendon and subacromial space parameters measured on ultrasonographic imaging in subacromial impingement syndrome.

PURPOSE: To characterize the supraspinatus tendon thickness, subacromial space, and the relationship between tendon thickness and subacromial space to further elucidate the mechanisms of subacromial impingement syndrome. METHODS: In a single-blind cross-sectional study, subjects were recruited with subacromial impingement syndrome (n = 20) and asymptomatic controls (n = 20) matched for age, gender, and hand dominance. Ultrasound images were collected using a 4-12-MHz linear transducer in B-mode of the supraspinatus tendon in the transverse (short axis) and the anterior aspect of the subacromial space outlet. Using image callipers, measurements of tendon thickness were taken at 3 points along the tendon and averaged for a single thickness measure. The subacromial space outlet was measured via the acromiohumeral distance (AHD) defined by the inferior acromion and superior humeral head. The occupation ratio was calculated as the tendon thickness as a percentage of AHD. RESULTS: The subacromial impingement syndrome group had a significantly thicker tendon (mean difference = 0.6 mm, p = 0.048) and a greater tendon occupation ratio (mean difference = 7.5 %, p = 0.014) compared to matched controls. There were no AHD group differences. CONCLUSIONS: The supraspinatus tendon was thicker and occupied a greater percentage of AHD, supporting an intrinsic mechanism. An extrinsic mechanism of tendon compression is theoretically supported, but future imaging studies need to confirm direct compression with elevation. Treatment to reduce tendon thickness may reduce symptoms, and surgical intervention to increase subacromial space may be considered if tendon compression can be verified.

Intra-rater reliability of ultrasound imaging of wrist extensor muscles in patients with tetraplegia.

OBJECTIVES: (i) To determine the intra-rater reliability and precision of the ultrasound cross-sectional area (CSA) measurements of the wrist extensors in individuals with spinal cord injury (SCI), and (ii) to determine whether tetraplegia has a negative influence on the reliability and precision for these measurements. DESIGN: A repeated-measures cross-sectional study. SETTINGS: Clinical hospital and academic settings. METHODS: The study was conducted with 20 men with SCI (9 paraplegia and 11 tetraplegia) and 10 able-bodied controls. Ultrasound images were captured of the right side extensor carpi radialis-longus (ECRL) and the extensor digitorum communis (EDC) were captured in 2 sessions separated by 48-72 hours. RESULTS: The intraclass correlation coefficients for the CSA measurements of the ECRL and EDC muscles were greater than 0.87 for all 3 groups. The standard error of the measure (SEM) ranged from 0.11-0.22 cm(2) for the ECRL and 0.13-0.27 cm(2) for the EDC. The minimal detectable change of ECL ranged from 0.16 to 0.31 cm(2) and of EDC from 0.19 to 0.38 cm(2). The group differences in muscle CSA of both muscles were found; these differences were greater than the calculated minimal detectable changes. The intraclass correlation coefficients were lower and the SEMs and minimal detectable changes were higher for the group with tetraplegia compared with the able-bodied controls and the group with paraplegia. CONCLUSIONS: This study documented substantial intra-rater reliability of measurements of the ECRL and ECD CSA by using ultrasound images, which support the use of this technique to effectively evaluate the musculoskeletal changes after SCI and during rehabilitation. Skeletal muscle atrophy in persons with tetraplegia might have a negative influence on the reliability and precision of these CSA measurements; however, these differences in reliability and precision are not of clinical significance.

Differences in scapular orientation, subacromial space and shoulder pain between the full can and empty can tests.

BACKGROUND: The empty and full can arm positions are used as diagnostic tests and in therapeutic exercise programs for patients with subacromial impingement syndrome. The adverse effects of these arm positions on the rotator cuff have not been fully described. The purpose of this investigation was to compare the acromio-humeral distance, three-dimensional scapular position, and shoulder pain during maximum isometric contractions in the empty and full can arm positions. METHODS: Subjects with subacromial impingement syndrome (n=28) and a matched control group without shoulder pain (n=28) participated. Acromio-humeral distance, scapular/clavicular positions and shoulder pain were measured during maximal isometric contractions in each position. FINDINGS: No difference was found in acromio-humeral distance (P=0.314) between the arm positions or between the groups (P=0.598). The empty can position resulted in greater scapular upward rotation (P<0.001, difference=4.9°), clavicular elevation (P<0.001, difference=2.7°), clavicular protraction (P=0.001, difference=2.5°) and less posterior tilt (P<0.001, difference=3.8°) than the full can position. No differences in the scapular positions were found between the groups. Positive correlations were seen between the scapular positions in the control and not in the subacromial impingement group. INTERPRETATION: Our results did not show a difference in acromio-humeral distance between the arm positions or groups, indicating that the kinematic differences between the positions are not associated with altered acromio-humeral distance. The increased pain in the EC position might be due to the lack of an association amongst the scapular positions rather than the deficiency of a single scapular motion.

Scapular kinematics and subacromial-impingement syndrome: a meta-analysis.

CONTEXT: The literature does not present a consistent pattern of altered scapular kinematics in patients with shoulder-impingement syndrome (SIS). OBJECTIVES: To perform meta-analyses of published comparative studies to determine the consistent differences in scapular kinematics between subjects with SIS and controls. In addition, the purpose was to analyze factors of the data-collection methods to explain the inconsistencies in reported kinematics. The results of this study will help guide future research and enable our understanding of the relationship between scapular kinematics and SIS. EVIDENCE ACQUISITION: A search identified 65 studies; 9 papers met inclusion criteria. Sample sizes, means, and SDs of 5 scapular-kinematic variables were extracted or obtained from each paper's lead author. Standard difference in the mean between SIS and controls was calculated. Moderator variables were plane of arm elevation, level of arm elevation (ARM) and population (POP). EVIDENCE SYNTHESIS: Overall, the SIS group had less scapular upward rotation (UR) and external rotation (ER) and greater clavicular elevation (ELE) and retraction (RET) but no differences in scapular posterior tilt (PT). In the frontal plane, SIS subjects showed greater PT and ER, and in the scapular plane, less UR and ER and greater ELE and RET. There was also greater ELE and RET in the sagittal plane. There was less UR at the low ARM and greater ELE and RET at the high ARM with SIS. Athletes and overhead workers showed less UR, while athletes showed greater PT and workers showed less PT and ER. The general population with SIS had greater ELE and RET only. CONCLUSIONS: Subjects with SIS demonstrated altered scapular kinematics, and these differences are influenced by the plane, ARM, and POP. Athletes and overhead workers have a different pattern of scapular kinematics than the general population. The scapular plane is most likely to demonstrate altered kinematics. These factors should be considered when designing futures studies to assess the impact of altered kinematics in patients with SIS.

Scapular muscle activity in overhead athletes with symptoms of secondary shoulder impingement during closed chain exercises.

OBJECTIVE: To determine the amount of muscle activation in 4 scapular muscles in overhead athletes with and without a history of secondary shoulder impingement, during 3 upper extremity closed chain exercises. DESIGN: One-between (group), one-within (exercise) repeated measures. SETTING: Controlled laboratory study. PARTICIPANTS: Overhead athletes (n=15; mean age +/- SD, 21.0+/-2.5 y; mean height +/- SD, 176.0+/-7.8 cm; mean weight +/- SD, 76.1+/-13.4 kg) demonstrating with symptoms of shoulder impingement and overhead athletes (n=15; mean age +/- SD, 20.4+/-3.8 y; mean height +/- SD, 174.1+/-9.7 cm; mean weight +/- SD, 73.3+/-11.7 kg) with no shoulder pathologies. INTERVENTIONS: Subjects completed 5 individual trials of a standard push-up, a push-up on an unstable surface, and a revolution on a shoulder rehabilitation device while electromyography (EMG) recorded muscle activity of the serratus anterior, upper trapezius, middle trapezius, and lower trapezius. MAIN OUTCOME MEASURES: The mean EMG data for the 4 muscles from the standard push-up, push-up on an unstable surface, and shoulder rehabilitation device trials were normalized as a percentage of a maximum voluntary isometric contraction for each muscle. RESULTS: There was a statistically significant interaction for the middle trapezius (F(2,56)=3.856; P=.027). The shoulder impingement push-up on an unstable surface (33.76%+/-26.45%) had significantly greater activation compared with the shoulder impingement standard push-up (25.88%+/-13.76%), the shoulder impingement shoulder rehabilitation device (9.40%+/-5.86%), and the nonpathology push-up on an unstable surface (19.49%+/-7.73%). The shoulder impingement standard push-up had significantly greater activation compared with the shoulder impingement shoulder rehabilitation device and nonpathology standard push-up (17.99%+/-7.31%). The nonpathology standard push-up and nonpathology push-up on an unstable surface had significantly greater activation compared with the nonpathology shoulder rehabilitation device (7.95%+/-4.30%). CONCLUSIONS: These results suggest that the muscle activation of the middle trapezius differs in overhead athletes with a history of secondary shoulder impingement compared with those who lack this history during closed chain exercise, as well as within the 3 closed chain exercises. The levels of muscle activation of the serratus anterior and upper trapezius during these closed chain exercises were similar between the 2 groups. These results support the use of closed chain exercises in the rehabilitation process of overhead athletes with secondary shoulder impingement. However, clinicians should consider the muscle(s) of interest when selecting an exercise.