Current concepts in the rehabilitation of the overhead throwing athlete

The association of scapular kinematics and glenohumeral joint pathologies

There is a growing body of literature associating abnormal scapular positions and motions, and, to a lesser degree, clavicular kinematics with a variety of shoulder pathologies. The purpose of this manuscript is to (1) review the normal kinematics of the scapula and clavicle during arm elevation, (2) review the evidence for abnormal scapular and clavicular kinematics in glenohumeral joint pathologies, (3) review potential biomechanical implications and mechanisms of these kinematic alterations, and (4) relate these biomechanical factors to considerations in the patient management process for these disorders. There is evidence of scapular kinematic alterations associated with shoulder impingement, rotator cuff tendinopathy, rotator cuff tears, glenohumeral instability, adhesive capsulitis, and stiff shoulders. There is also evidence for altered muscle activation in these patient populations, particularly, reduced serratus anterior and increased upper trapezius activation. Scapular kinematic alterations similar to those found in patient populations have been identified in subjects with a short rest length of the pectoralis minor, tight soft-tissue structures in the posterior shoulder region, excessive thoracic kyphosis, or with flexed thoracic postures. This suggests that attention to these factors is warranted in the clinical evaluation and treatment of these patients. The available evidence in clinical trials supports the use of therapeutic exercise in rehabilitating these patients, while further gains in effectiveness should continue to be pursued.

LEVEL OF EVIDENCE

Level 5.

Shoulder injuries in the overhead athlete

The overhead throwing motion is an extremely skillful and intricate movement. When pitching, the overhead throwing athlete places extraordinary demands on the shoulder complex subsequent to the tremendous forces that are generated. The thrower's shoulder must be lax enough to allow excessive external rotation but stable enough to prevent symptomatic humeral head subluxations, thus requiring a delicate balance between mobility and functional stability. We refer to this as the "thrower's paradox." This balance is frequently compromised and believed to lead to various types of injuries to the surrounding tissues. Frequently, injuries can be successfully treated with a well-structured and carefully implemented nonoperative rehabilitation program. The key to successful nonoperative treatment is a thorough clinical examination and accurate diagnosis. Rehabilitation follows a structured, multiphase approach, with emphasis on controlling inflammation, restoring muscles' balance, improving soft tissue flexibility, enhancing proprioception and neuromuscular control, and efficiently returning the athlete to competitive throwing. Athletes often exhibit numerous adaptive changes that develop from the repetitive microtraumatic stresses occurring during overhead throwing. Treatment should include the restoration of these adaptations.

LEVEL OF EVIDENCE

Level 5.

Humeral torsion and passive shoulder range in elite volleyball players

OBJECTIVES

To evaluate variations in humeral torsion in elite male volleyball players and determine whether these changes are related to training history, retrospective injury history and volleyball performance.

DESIGN AND SETTING

Cross sectional design.

PARTICIPANTS

Twenty-four elite male volleyball players.

MAIN OUTCOME MEASURES

Humeral torsion, passive gleno-humeral rotation ranges and the available internal and external rotation from the humeral torsion neutral position of the dominant and non-dominant arm were measured. Training history and retrospective injury status were ascertained from a questionnaire. Performance was assessed by coach perceived spiking ability and peak serve velocity measures.

RESULTS

Humeral torsion angles demonstrated the dominant arm to be on average 9.6 degrees more retroverted than the non-dominant arm (p=0.00). In the comparison of volleyball players with and without a history of overuse upper limb injury the most significant finding is on the non-dominant side, those with a history of injury had significantly decreased available external rotation from the humeral torsion neutral position (mean difference=-15.1, p=0.04). There was an unexpected negative weak relationship between age commenced and decreased humeral retroversion (r=-0.413, p=0.045). There did not appear to be any relationship between humeral torsion and performance measures.

CONCLUSION

The dominant arm of elite male volleyball athletes is more retroverted. There was a tendency for stronger findings in the non-dominant arm in volleyball players with retrospective injury history. We were unable to find any significant correlation between humeral torsion angle and performance measures.

Radiographic analysis of commonly prescribed scapular exercises

HYPOTHESIS

The performance of scapular exercises in the context of a clinical model of fatigue will result in superior migration of the humeral head and alterations in shoulder kinematics on radiographic analysis.

MATERIALS AND METHODS

Six healthy male volunteers underwent a series of radiographs before and immediately following two scapular exercises. To reproduce a practice setting a clinical model of muscle fatigue was utilized. Radiographs were taken at various degrees of elevation. Glenohumeral angle (GA), scapulothoracic angle (SA), and the position of the humeral head on the glenoid (excursion) were measured on each radiograph. Two-tailed paired sample t-test were used to compare pre-fatigue to post fatigue measures.

RESULTS

Following fatigue there was a significant increase in excursion at 45, 90, and 135 degrees of elevation indicating superior migration of the humeral head. There was an increase in SA from 0 to 45 degrees and a decrease in GA from 45 to 90 degrees of elevation. From 90 to 135 degrees an increase in GA was observed.

DISCUSSION

The amount of superior migration of the humeral head observed following exercise was consistent with previously reported amounts of superior migration in patients with subacromial impingement. The alterations that occurred in shoulder kinematics following exercise may have resulted from parascapular muscle fatigue as well as rotator cuff muscle insufficiency.

CONCLUSION

In the context of a clinical model of fatigue, these scapular exercises resulted in superior migration of the humeral head and alterations in shoulder kinematics on radiographic analysis in healthy subjects.

LEVEL OF EVIDENCE

Basic science study.

The acute effects of sleeper stretches on shoulder range of motion

CONTEXT

The deceleration phase of the throwing motion creates large distraction forces at the shoulder, which may result in posterior shoulder tightness and ensuing alterations in shoulder range of motion (ROM) and may result in an increased risk of shoulder injury. Researchers have hypothesized that various stretching options increase this motion, but few data on the effectiveness of treating such tightness are available.

OBJECTIVE

To evaluate the acute effects of "sleeper stretches" on shoulder ROM.

DESIGN

Descriptive with repeated measures.

SETTING

Biomechanics laboratory and 2 separate collegiate athletic training facilities.

PATIENTS OR OTHER PARTICIPANTS

Thirty-three National Collegiate Athletic Association Division I baseball players (15 pitchers, 18 position players; age = 19.8 +/- 1.3 years, height = 184.7 +/- 6.4 cm, mass = 84.8 +/- 7.7 kg) and 33 physically active male college students (age = 20.1 +/- 0.6 years, height = 179.6 +/- 6.6 cm, mass = 83.4 +/- 11.3 kg) who reported no recent participation (within 5 years) in overhead athletic activities.

INTERVENTION(S)

Range-of-motion measurements of the dominant shoulder were assessed before and after completion of 3 sets of 30-second passive sleeper stretches among the baseball players. The ROM measurements in the nonthrower group were taken using identical methods as those in the baseball group, but this group did not perform any stretch or movement between measurements.

MAIN OUTCOME MEASURE(S)

Internal and external glenohumeral rotation ROM and posterior shoulder motion (glenohumeral horizontal adduction).

RESULTS

In the baseball group, posterior shoulder tightness, internal rotation ROM, and external rotation ROM were -3.5 degrees +/- 7.7 degrees , 43.8 degrees +/- 9.5 degrees , and 118.6 degrees +/- 10.9 degrees , respectively, before the stretches and were -1.2 degrees +/- 8.8 degrees , 46.9 degrees +/- 9.8 degrees , and 119.2 degrees +/- 11.0 degrees , respectively, after the stretches. These data revealed increases in posterior shoulder motion (P = .01, effect size = 0.30) and in internal shoulder rotation (P = .003, effect size = 0.32) after application of the stretches. No other differences were observed in the baseball group, and no differences were noted in the nonthrower group.

CONCLUSIONS

Based on our results, the sleeper stretches produced a statistically significant acute increase in posterior shoulder flexibility. However, this change in motion may not be clinically significant.

Muscle strength and range of motion in adolescent pitchers with throwing-related pain: implications for injury prevention

BACKGROUND

A high prevalence of throwing-related shoulder and elbow pain has been documented in adolescent baseball pitchers.

HYPOTHESIS

Pitchers with a history of throwing-related pain will have weakened dominant-arm posterior shoulder musculature and greater dominant-arm glenohumeral total range of motion (ROM) loss compared with pitchers without throwing-related pain.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-three adolescent pitchers (age 15.7 +/- 1.4 years) were tested. Twelve pitchers had throwing-related pain in the prior season and were currently symptom-free, while the remaining 11 pitchers had no such history of pain. Internal and external rotation ROM and muscle strength (lower trapezius, middle trapezius, rhomboids, latissimus dorsi, supraspinatus, internal rotators, external rotators) were measured bilaterally. Dominant versus nondominant differences in ROM and strength were compared between pitchers with and without throwing-related pain.

RESULTS

As a whole, the group of 23 pitchers had a loss of internal rotation ROM (13 degrees +/- 10 degrees , P < .001) and gain in external rotation ROM (11 degrees +/- 10 degrees , P < .001) on the dominant versus nondominant arm, with no effect on total ROM (2 degrees +/- 7 degrees loss, P = .14). There was no difference in bilateral comparison of total ROM between pitchers with and without throwing-related pain. Dominant versus nondominant muscle strength was lower (P < .05) for the pain group versus nonpain group for the middle trapezius (7% +/- 19% vs 22% +/- 12%) and supraspinatus (-4% +/- 27% vs 14% +/- 14%) and higher (P < .05) for the internal rotators (19% +/- 14% vs 6% +/- 12%).

CONCLUSION

Throwing-related pain in this population may be due to the inability of weakened posterior shoulder musculature to tolerate stress imparted on it by adaptively strengthened propulsive muscles.

CLINICAL RELEVANCE

Selective posterior shoulder strengthening may be indicated in rehabilitative and injury prevention programs for adolescent pitchers.

Comparison of two patient-based outcome measures for shoulder instability after nonoperative treatment

This study compared the responsiveness and minimal clinically important differences of the Oxford Instability Shoulder Score (OISS) and Shoulder Rating Questionnaire (SRQ). Ninety-three patients referred to physiotherapy with shoulder instability (100 shoulders) completed the questionnaires at the initial appointment and at 1 and 9 months later. A subjective rating of change was also obtained. Both questionnaires were able to detect change (effect sizes 1.16 OISS and 0.99 SRQ). The OISS change scores correlated more consistently with patients' subjective responses. The minimal detectable change (MDC90) scores were 16% (7 points) for the OISS and 17% (8 unweighted points) for the SRQ. The minimal clinically important difference (MCID) was between 9%, 4.5 points ("slightly better" and "much better") and 13.5%, 6.5 points ("much better") for the OISS, dependent on the subjective descriptors used, and 11% (4 unweighted points) for SRQ. The MCID change scores varied in relation to the baseline level of function.

Scapular positioning in athlete's shoulder : particularities, clinical measurements and implications

Despite the essential role played by the scapula in shoulder function, current concepts in shoulder training and treatment regularly neglect its contribution. The 'scapular dyskinesis' is an alteration of the normal scapular kinematics as part of scapulohumeral rhythm, which has been shown to be a nonspecific response to a host of proximal and distal shoulder injuries. The dyskinesis can react in many ways with shoulder motion and function to increase the dysfunction. Thoracic kyphosis, acromio-clavicular joint disorders, subacromial or internal impingement, instability or labral pathology can alter scapular kinematics. Indeed, alteration of scapular stabilizing muscle activation, inflexibility of the muscles and capsule-ligamentous complex around the shoulder may affect the resting position and motion of the scapula. Given the interest in the scapular positioning and patterns of motion, this article aims to give a detailed overview of the literature focusing on the role of the scapula within the shoulder complex through the sports context. Such an examination of the role of the scapula requires the description of the normal pattern of scapula motion during shoulder movement; this also implies the study of possible scapular adaptations with sports practice and scapular dyskinesis concomitant to fatigue, impingement and instability. Different methods of scapular positioning evaluation are gathered from the literature in order to offer to the therapist the possibility of detecting scapular asymmetries through clinical examinations. Furthermore, current concepts of rehabilitation dealing with relieving symptoms associated with inflexibility, weakness or activation imbalance of the muscles are described. Repeating clinical assessments throughout the rehabilitation process highlights improvements and allows the therapist to actualize rationally his or her intervention. The return to the field must be accompanied by a transitory phase, which is conducive to integrating new instructions during sports gestures. On the basis of the possible scapular disturbance entailed in sports practice, a preventive approach that could be incorporated into training management is encouraged.

Differences in EMG activity in scapular plane abduction under variable arm positions and loading conditions

PURPOSE

The present study was performed to investigate the activities of four shoulder muscles-the supraspinatus, the middle deltoid, the infraspinatus, and the upper trapezius-in scapular plane abduction in various exercise conditions.

METHODS

Eight male subjects (mean +/- SD: 23.4 +/- 1.3 yr) with an asymptomatic nondominant left shoulder participated in this study. Each subject performed scapular plane abduction with humeral external rotation (full can position) and with humeral internal rotation (empty can position), producing constant target torques of 4 and 12 N.m, respectively. In addition, the subjects performed each exercise in the supine position with the limb supported by straps. Electromyogram (EMG) was recorded with intramuscular electrodes at the supraspinatus and infraspinatus, and with surface electrodes placed at the middle deltoid and upper trapezius. The EMG activity (RMS) of each muscle was normalized according to the highest EMG activity (100% MVC) during a maximum manual muscle test for the corresponding muscle (% MVC).

RESULTS

EMG activity of the supraspinatus was significantly greater than those of the other shoulder muscles in the full can position from 10-20 degrees to 50-60 degrees arcs with a target torque of 4 N.m (P < 0.05). In contrast, the supraspinatus and middle deltoid showed similar EMG activities under other exercise conditions.

CONCLUSIONS

These results suggest that there is an exercise condition that induces greater activity of the supraspinatus in scapular plane abduction.

Torque and force production during shoulder external rotation: differences between transverse and sagittal planes

In joints with 3 degrees of freedom, such as the shoulder joint, the association of different movements results in changes in the behavior of the moment arm of the muscles. The capacity of torque production for the same movement can be changed when movements take place in a different plane. The objective of this study is to quantify differences between torque production and resultant force estimated during the shoulder external rotation in two movement planes: the transverse and sagittal planes (with 90 degrees of shoulder abduction). Eight individuals were evaluated using an isokinetic dynamometer and an eletrogoniometer for movements in the transverse plane and six individuals for movements in the sagittal plane. The results showed that the execution of the external rotation in the sagittal plane allowed greater torque magnitudes and resultant force compared with those in the transverse plane, probably owing to a prestretching of infraspinatus and teres minor.

Changes in shoulder and elbow passive range of motion after pitching in professional baseball players

BACKGROUND

The overhead throwing athlete has unique range of motion characteristics of the shoulder and elbow. Numerous theories exist to explain these characteristics; however, the precise cause is not known. Although it is accepted that range of motion is altered, the acute effect of baseball pitching on shoulder and elbow range of motion has not been established.

HYPOTHESIS

There will be a reduction in passive range of motion immediately after baseball pitching.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sixty-seven asymptomatic male professional baseball pitchers participated in the study. Passive range of motion measurements were recorded using a customized bubble goniometer for shoulder external rotation, shoulder internal rotation, total shoulder rotational motion, elbow flexion, and elbow extension on the dominant and nondominant arms. Testing was performed on the first day of spring training. Measurements were taken before, immediately after, and 24 hours after pitching.

RESULTS

A significant decrease in shoulder internal rotation (-9.5 degrees), total motion (-10.7 degrees), and elbow extension (-3.2 degrees) occurred immediately after baseball pitching in the dominant shoulder (P<.001). These changes continued to exist 24 hours after pitching. No differences were noted on the nondominant side.

CONCLUSION

Passive range of motion is significantly decreased immediately after baseball pitching. This decrease in range of motion continues to be present 24 hours after throwing. High levels of eccentric muscle activity have previously been observed in the shoulder external rotators and elbow flexors during pitching. These eccentric muscle contractions may contribute to acute musculotendinous adaptations and altered range of motion. The results of this study may suggest a newly defined mechanism to range of motion adaptations in the overhead throwing athlete resulting from acute musculoskeletal adaptations, in addition to potential osseous and capsular adaptations.

Isometric shoulder girdle strength of healthy young adults

BACKGROUND

Shoulder girdle muscles are important for stabilizing the scapula and orienting the glenoid for upper-extremity motion. However, data describing shoulder girdle strength and how it varies with position is lacking.

METHODS

A series of experiments was conducted to measure isometric strength at three positions each for elevation, depression, protraction, and retraction of the shoulder girdle. Nineteen healthy men and women (ages 19 to 23 years) participated in the study. Subjects were seated in a custom apparatus and asked to push or pull with extended arms as forcefully as possible against force-sensing handles. Shoulder girdle elevation angle and protraction angle were recorded with a video system during the tests.

FINDINGS

In each direction the force generated by the shoulder girdle varied significantly (P<0.05) and monotonically with position. The greatest forces in elevation (mean 1101N, SD 370N) and protraction (mean 1117N, SD 471N) occurred at the most depressed and retracted positions, respectively. Similarly, the greatest forces in depression (mean 810N, SD 274N) and retraction (mean 914N, SD 362N) occurred at the most elevated and protracted positions, respectively. Male subjects generated 38-81% greater force than female subjects, depending on direction. Shoulder girdle elevation and protraction strengths correlated significantly (P<0.01) with bodyweight (r>0.71) and with one-repetition maximum bench-press strength (r>0.83).

INTERPRETATION

Functional tasks such as bench-press may be good indicators of shoulder girdle strength in some directions.

Considerations for Maintenance of Postural Alignment for Voice Production

There is general agreement that postural alignment is important in optimizing voice function. A number of articles have illuminated the way in which posture, particularly of the cervical spine, is directly related to vocal resonance and pitch control. Despite frequent involvement in muscle training, few speech pathologists have the background in exercise physiology necessary to appreciate the contribution of muscular length-tension relationships to postural alignment. The purpose of this article is to provide voice therapists with information to help them formulate appropriate recommendations for improving postural alignment. This article synthesizes information from the literature regarding the role of muscular length-tension balance in the attainment and maintenance of postural alignment. Important considerations in the assessment of muscle tension and weakness are presented along with advice regarding application to the treatment of voice-disordered patients. Concepts detailed include agonist/antagonist relationships, the biomechanics of stretching, postural assessment, and the relationship between muscle tension and muscle weakness. The role of both stretching and strength-based training is discussed. Specific exercises with emphasis on altering the alignment of the cervical and thoracic spine are presented with suggestions for their use in the clinic. There is growing understanding of the physiology behind recommendations of voice teachers and therapists to maintain optimal alignment. To effectively mediate postural misalignment, clinicians must have knowledge of the length-tension relationships between muscles. This understanding will lead to better interventions for postural alignment.

Reliability, precision, accuracy, and validity of posterior shoulder tightness assessment in overhead athletes

BACKGROUND

Posterior shoulder tightness with subsequent loss of humeral internal rotation range of motion has been linked to upper extremity lesions in overhead athletes. A valid clinical assessment is necessary to accurately identify posterior shoulder tightness as a contributor to injury.

PURPOSE

To describe a modified supine assessment of posterior shoulder tightness by establishing the reliability, precision, clinical accuracy, and validity of the assessment.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

Intrasession, intersession, and intertester reliability and precision were established by comparing the commonly used side-lying assessment of posterior shoulder tightness and the described modified supine assessment. Clinical accuracy of both methods was obtained using an electromagnetic tracking device to track humeral and scapular motion. Construct validity was established by identifying posterior shoulder tightness in a group of overhead athletes (baseball pitchers and tennis players) reported in the literature to have limited humeral internal rotation and posterior shoulder tightness.

RESULTS

The side-lying intrasession intraclass correlation coeffecient (standard error of measurement), intersession intraclass correlation coeffecient (standard error of measurement), and intertester intraclass correlation coeffecient (standard error of measurement) were 0.83 cm (0.9), 0.42 cm (1.7), and 0.69 cm (1.4), respectively. The supine intrasession intraclass correlation coeffecient (standard error of measurement), intersession intraclass correlation coeffecient (standard error of measurement), and intertester intraclass correlation coeffecient (standard error of measurement) were 0.91 degrees (1.1 degrees ), 0.75 degrees (1.8 degrees ), and 0.94 degrees (1.8 degrees ), respectively. In side-lying, the clinical accuracy expected was 0.9 +/- 0.6 cm of error while, when measured supine, it was 3.5 degrees +/- 2.8 degrees of error. Both assessments resulted in minimal scapular protraction (approximately 3.5 degrees ). Between groups, baseball pitchers and tennis players had significantly less internal rotation range of motion (P < .0001) and greater posterior shoulder tightness (P = .004) when measured in supine, but not in side-lying (P = .312).

CONCLUSION

Both methods resulted in good clinician accuracy and precision, suggesting that both can be performed accurately. The supine method can be assessed more reliably than side-lying between both sessions and testers.

CLINICAL RELEVANCE

Clinicians may want to consider use of the supine method given the higher reliability, validity, and similar precision and clinical accuracy.

Rehabilitation and shoulder function after suprascapular nerve entrapment operation in a volleyball player

The purpose of this report was to determine a detailed description of a rehabilitation programme of a volleyball player who had a decompression surgery for suprascapular nerve entrapment and to expose the long-term functional outcomes which lead to successful results.

Rehabilitation of scapular muscle balance: which exercises to prescribe?

BACKGROUND

Strengthening exercises for the scapular muscles are used in the treatment of scapulothoracic dysfunction related to shoulder injury. In view of the intermuscular and intramuscular imbalances often established in these patients, exercises promoting lower trapezius (LT), middle trapezius (MT), and serratus anterior (SA) activation with minimal activity in the upper trapezius (UT) are recommended.

HYPOTHESIS

Of 12 commonly used trapezius strengthening exercises, a selection can be performed for muscle balance rehabilitation, based on a low UT/LT, UT/MT, or UT/SA muscle ratio.

STUDY DESIGN

Controlled laboratory study.

METHODS

Electromyographic activity of the 3 trapezius parts and the SA was measured in 45 healthy subjects performing 12 commonly described scapular exercises, using surface electromyography.

RESULTS

For each intramuscular trapezius ratio (UT/LT, UT/MT), 3 exercises were selected for restoration of muscle balance. The exercises side-lying external rotation, side-lying forward flexion, prone horizontal abduction with external rotation, and prone extension were found to be the most appropriate for intramuscular trapezius muscle balance rehabilitation. For the UT/SA ratio, none of the exercises met the criteria for optimal intermuscular balance restoration.

CONCLUSION

In cases of trapezius muscle imbalance, some exercises are preferable over others because of their low UT/LT and UT/MT ratios.

CLINICAL RELEVANCE

In the selection of rehabilitation exercises, the clinician should have a preference for exercises with high activation of the LT and MT and low activity of the UT.

Use of a movement system impairment diagnosis for physical therapy in the management of a patient with shoulder pain

STUDY DESIGN

Case report.

BACKGROUND

Based on our assumption that subtle deviations in the precision of shoulder movement cause tissue injury, we have developed a set of movement-related diagnoses for shoulder problems. The purposes of this case report are to (1) illustrate the use of a movement system impairment (MSI) diagnosis in a patient with shoulder pain, (2) illustrate how the MSI diagnosis guided treatment prescription, and (3) describe the outcomes of treatment based on a MSI diagnosis for shoulder impingement.

CASE DESCRIPTION

The patient was a 46-year-old female with recurrent right-shoulder pain of 2 months' duration. Initially she reported that her pain was constant but varied in intensity and had increased gradually over time. Shoulder pain limited her ability to bicycle and perform reaching movements. The systematic clinical examination for assessing the patient's preferred alignment and movements included items related to pain, alignment, movement, muscle length, muscle strength, and function. Based on the examination, the MSI diagnosis was humeral anterior glide with scapular downward rotation. The treatment focused on correction of her shoulder alignment, functional movements, and associated impairments of muscle function. The patient was seen 4 times in 6 weeks.

OUTCOMES

The patient was pain free with all activities at 1 month and there was no recurrence of symptoms 3 years after the last physical therapy visit.

DISCUSSION

A MSI diagnosis of humeral anterior glide with scapular downward rotation guided physical therapy treatment and resulted in positive short- and long-term outcomes.

An Apparatus and Protocol to Measure Shoulder Girdle Strength

Muscles actuating the shoulder girdle are important for stabilizing the scapula and coordinating phased kinematics of the shoulder complex. If these muscles become weak or imbalanced, joint instability and injury may result. Reliable measurement of shoulder strength is thus important for prevention, diagnosis, and rehabilitation of shoulder problems. To date, studies quantifying the strength of the shoulder girdle are limited. The purpose of this work was to design and evaluate a custom apparatus and corresponding protocol for measuring maximal, voluntary, isometric strength of the shoulder girdle during various forms of shrugging exercise. A custom apparatus was constructed as a rigid frame with a vertical post supporting a seat, seat back, and horizontal beam. The beam extends laterally on either side beyond and around the shoulders of a seated subject. A pair of arm extension members pivots on the beam about an axis aligned with the shoulder flexion-extension axis. These members can be locked in place at any angle. Between them is mounted a force-sensing grip assembly, which can be adjusted proximally or distally to accommodate varying shoulder girdle positions. Subjects grasp the grip assembly handles with extended elbows and push or pull as forcefully as possible. Nine female and ten male subjects participated in a protocol using the apparatus to measure maximum isometric force generated at three positions each for elevation, depression, protraction, and retraction of the shoulder girdle (3positions×4modes=12tests). A video motion capture system was used to measure shoulder girdle angles. The reliability of the approach was evaluated based on the repeatability of measured shoulder elevation angle, protraction angle, and total force over three days of testing. The apparatus performed well during the tests, providing a stable, rigid, yet adjustable platform for measuring shoulder girdle strength. Repeatability of force measurements was interpreted as very good to excellent, with intraclass correlation coefficient (ICC) (2,1) values ranging from 0.83 to 0.95 for all tests except one (ICC=0.79). Repeatability of angle measurements was interpreted as good to excellent. For tests measuring elevation and depression strength, the ICC of elevation angle ranged from 0.85 to 0.89. For tests measuring protraction and retraction strength, the ICC of protraction angle ranged from 0.68 to 0.88. This type of apparatus could be an effective clinical tool for measuring strength in the shoulder girdle muscles. Use of the video motion capture system is optional.

Prolonged immobilization in abduction and neutral rotation for a first-episode anterior shoulder dislocation

STUDY DESIGN

Case report.

BACKGROUND

Patients who sustain first-episode anterior glenohumeral dislocations are at risk to develop chronic glenohumeral instability. Current treatment options after an initial anterior glenohumeral dislocation include immediate surgery, delayed surgery, or conservative interventions such as immobilization and strengthening exercises. Duration of immobilization is variable among formal studies. Recent research suggests that typical immobilization positions may not allow adequate healing and in fact may promote glenohumeral joint instability.

CASE DESCRIPTION

The patient was a 19-year-old male who sustained a first-episode anterior glenohumeral dislocation during athletic activity. Physical therapy management included a longer-than-typical period of immobilization and protected activity to allow for more complete healing. The shoulder abduction and neutral rotation immobilization position used with this patient may increase healing of structures that influence stability of the shoulder

OUTCOMES

At 13 weeks after the dislocation, the patient had full active and passive range of motion, near normal strength, and no complaints of pain or instability. At a 20-month follow-up the patient had resumed full activities of daily living including recreational sports without symptoms of instability.

DISCUSSION

Conservative intervention options for first-episode anterior shoulder dislocations need further study. Immobilization and protected activity periods should be adequate to allow for complete healing. The optimal positions for immobilization should be determined and implemented.

Glenohumeral internal rotation deficits in professional pitchers enrolled in an internal rotation stretching program

BACKGROUND

Repetitive throwing motion creates increased external rotation and decreased internal rotation in the glenohumeral joint. There is controversy regarding the contribution of osseous and soft tissue adaptations to these changes in rotation.

OBJECTIVE

To evaluate internal rotation deficits in the professional baseball thrower's shoulder and determine the impact of an internal rotation stretch program on that deficit.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Eighty-five male professional pitchers were evaluated in this study. Players were divided into 2 groups based on length of participation in an appropriate internal rotation stretch program. Data were collected on internal and external rotations and total range of motion in both dominant and nondominant arms using a goniometer. Internal rotation deficit (the lack of internal rotation relative to the opposite side) was calculated. Generalized comparative statistical tests were used.

RESULTS

Pitchers with 3 or more years in a stretch program (group 1) had greater internal rotation (74.3 degrees vs 54.3 degrees ) and greater total range of motion (217.0 degrees vs 194.2 degrees ) in dominant shoulders than did pitchers with less than 3 years (group 2). Total range of motion was greater in the dominant than in the nondominant arm for group 1. Internal rotation deficit in dominant arms was significantly greater for group 2 than for group 1. The analysis of dominant arm rotation relative to years in an internal rotation stretching program for pitchers in both groups showed a progressive increase in both internal rotation and total arc of motion with the number years in such a program plateauing after year 3.

CONCLUSION

The throwing motion shifts the total arc of motion toward external rotation and diminishes internal rotation. The increased external rotation may be attributable to increased humeral retroversion. The internal rotation deficit, however, is caused by soft tissue adaptations that can be addressed by consistent participation in a stretching program focused on internal rotation.

Understanding shoulder and elbow injuries in baseball

Repetitive overhead throwing exerts significant mechanical stress on the shoulder and elbow joint; this stress can lead to developmental anatomic changes in the young thrower. Asymptomatic pathology in the shoulder and elbow joint is prevalent and, with overuse, can progress to disabling injury. Joint injury occurs as a result of the body's inability to properly coordinate motion segments during the pitching delivery, leading to further structural damage. Identifying and preventing overuse is the key to avoiding injury, particularly in the young pitcher. Injury prevention and rehabilitation should center on optimizing pitching mechanics, core strength, scapular control, and joint range of motion.

The cam effect of the proximal humerus: its role in the production of relative capsular redundancy of the shoulder

PURPOSE

The purpose of this study was to investigate quantitatively the cam effect of the proximal humerus (whereby the anteroinferior capsule of the shoulder is tensioned in abduction-external rotation by virtue of asymmetric rotation of the eccentrically positioned humeral head), as well the extent to which a reduction in the cam effect would cause a relative capsular redundancy, in the cadaveric shoulder.

METHODS

Five fresh-frozen cadaveric shoulders were tested. K-wires were used to sequentially position the shoulder in 3 different positions: neutral anatomic position, with contact at the glenoid bare spot; 90 degrees-90 degrees neutral shift position, with contact at the glenoid bare spot; and 90 degrees-90 degrees posterosuperior shift position, with contact 4.3 mm posterosuperior to the glenoid bare spot. The topographic anterior band distance (TABD) was measured with the shoulder in each of the 3 positions. The relative redundancy that occurred by shifting the glenohumeral contact point was determined by subtracting the TABD in the 90 degrees-90 degrees posterosuperior shift position from the TABD in the 90 degrees-90 degrees neutral shift position.

RESULTS

The results of repeated-measures analysis of variance showed significant differences among the mean TABD values for the 3 positions (P < .010). There was a significant increase in TABD when the shoulder was brought from the neutral anatomic position to the 90 degrees-90 degrees neutral shift position (P < .020), confirming the cam effect of the proximal humerus in the 90 degrees-90 degrees position. Furthermore, the TABD decreased significantly when the 90 degrees-90 degrees neutral shift position changed to the 90 degrees-90 degrees posterosuperior shift position (P < .005), indicating a significant reduction in the cam effect with a concomitant relative redundancy in the anteroinferior capsuloligamentous complex.

CONCLUSIONS

The proximal humerus produces a significant cam effect on the anteroinferior capsule when the shoulder is brought into a position of 90 degrees abduction and 90 degrees external rotation. A reduction in the cam effect as a result of a posterosuperior shift of the glenohumeral contact point with the shoulder in the 90 degrees-90 degrees position results in a relative redundancy of the anteroinferior capsuloligamentous complex. This relative capsular redundancy, coupled with the pseudolaxity that occurs with SLAP lesions, can produce a degree of apparent anterior laxity that is independent of any true translational anterior instability.

CLINICAL RELEVANCE

The relative redundancy in the anteroinferior shoulder capsule caused by a decrease in the cam effect of the proximal humerus may have clinical implications in the pathophysiology of the disabled throwing shoulder. This relative redundancy is a secondary pseudolaxity, with the primary pathology being a tight posteroinferior capsule. Appropriate treatment (stretching of the posteroinferior capsule) of the primary pathology is a more appropriate initial treatment than instability surgery.

A randomized controlled comparison of stretching procedures for posterior shoulder tightness

STUDY DESIGN

Randomized controlled trial,

OBJECTIVES

To compare changes in shoulder internal rotation range of motion (ROM), for 2 stretching exercises, the "cross-body stretch" and the "sleeper stretch," in individuals with posterior shoulder tightness.

BACKGROUND

Recently, some authors have expressed the belief that the sleeper stretch is better than the cross-body stretch to address glenohumeral posterior tightness because the scapula is stabilized.

METHODS

Fifty-four asymptomatic subjects (20 males, 34 females) participated in the study. The control group (n=24) consisted of subjects with a between-shoulder difference in internal rotation ROM of less than 10 degrees, whereas those subjects with more than a 10 degrees difference were randomly assigned to 1 of 2 intervention groups, the sleeper stretch group (n=15) or the cross-body stretch group (n=15). Shoulder internal rotation ROM, with the arm abducted to 90 degrees and scapula motion prevented, was measured before and after a 4-week intervention period. Subjects in the control group were asked not to engage in any new stretching activities, while subjects in the 2 stretching groups were asked to perform stretching exercises on the more limited side only, once daily for 5 repetitions, holding each stretch for 30 seconds.

RESULTS

The improvements in internal rotation ROM for the subjects in the cross-body stretch group (mean +/- SD, 20.0 degrees +/- 12.9 degrees) were significantly greater than for the subjects in the control group (5.9 degrees +/- 9.4 degrees, P = .009). The gains in the sleeper stretch group (12.4 degrees +/- 10.4 degrees) were not significant compared to those of the control group (P = .586) and those of the cross-body stretch group (P = .148).

CONCLUSIONS

The cross-body stretch in individuals with limited shoulder internal rotation ROM appears to be more effective than no stretching in controls without internal rotation asymmetry to improve shoulder internal rotation ROM. While the improvement in internal rotation from the cross-body stretch was greater than for the sleeper stretch and of a magnitude that could be clinically significant, the small sample size likely precluded statistical significance between groups.

Scapular angular positioning at end range internal rotation in cases of glenohumeral internal rotation deficit

STUDY DESIGN

Controlled laboratory study.

OBJECTIVES

Investigate the relationship between glenohumeral internal rotation range-of-motion deficit and 3-dimensional scapular angular positioning during active arm movements in participants with recent participation in overhead sports activity.

BACKGROUND

Subacromial impingement is one of the most common shoulder pathologies and is multifactorial in etiology. Posterior glenohumeral joint capsule tightness has been theorized to contribute to one potential causal factor: abnormal scapular positioning.

METHODS AND MEASURES

Twenty-three subjects, who had participated in competitive sports involving overhead activity within the last 5 years, were categorized into 2 groups based on the degree of glenohumeral internal rotation deficit (20% deficit threshold). Scapular angular positioning of subjects performing shoulder internal rotation from 90 degrees flexion and abduction shoulder positions was evaluated using 3-dimensional electromagnetic surface tracking. Additional sensors monitored trunk and humeral motion. Scapular position data at end range glenohumeral internal rotation, along with glenohumeral internal rotation range of motion measurements, were used to analyze the relationship between glenohumeral internal rotation deficit and scapular position using 2-way ANOVA and regression analyses.

RESULTS

The internal rotation deficit group had significantly greater scapular anterior tilt (9.2 degrees difference, P = .04) across positions, as compared to the control group. Regression analysis demonstrated a significant association between glenohumeral internal rotation deficit and scapular position (tilting) during flexed internal rotation (r(2) = 0.37, P = .03) and for scapular position (anterior tilting and upward rotation) during abducted internal rotation (r = 0.35, P = .036).

CONCLUSIONS

These findings demonstrate a significant relationship between glenohumeral internal rotation deficit and abnormal scapular positioning, particularly increased anterior tilt. This relationship identifies a possible mechanism for development of excessive scapular anterior tilt.

Path of glenohumeral articulation throughout the rotational range of motion in a thrower's shoulder model

BACKGROUND

Overhead-throwing athletes have increased external and diminished internal glenohumeral rotation that may alter glenohumeral kinematics.

PURPOSE

To quantify the kinematic changes present in a cadaveric model of a thrower's shoulder.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 8 fresh-frozen cadaveric shoulders, the rotator cuff and overlying muscles were removed, and the glenohumeral capsule, coracoacromial ligament, and coracohumeral ligament were left intact. The scapula was fixed, and the humerus was placed in 90 degrees of shoulder abduction in a 6 degrees of freedom testing device. A compressive force of 44 N was applied. A thrower's shoulder model was created, and sequential conditions were examined: intact, after anterior stretching, and after the addition of posterior-inferior capsular plication. Kinematic measurements were obtained through a complete range of glenohumeral rotation.

RESULTS

Glenohumeral external rotation increased 16%, from 149 degrees to 173 degrees (P < .001), after stretching in external rotation and remained increased by 11% to 166 degrees (P < .001) after posterior-inferior capsular plication. With the addition of the posterior-inferior capsular plication, internal rotation averaged 7 degrees , which was not significantly different from the intact state (11 degrees, P = .55) or the stretched state (16 degrees, P = .07). The total glenohumeral rotation after stretching followed by posterior-inferior capsular plication did not differ significantly from intact state (P = .25). At maximum external rotation, the humeral head apex was shifted posteriorly in the stretched (P = .003) and plicated (P < .001) states compared with the intact state. The humeral head apex was posteriorly displaced at 135 degrees and 150 degrees of external rotation compared with the intact condition (P = .039 and .049, respectively). In maximum internal rotation, anterior stretching had no significant effect on the humeral head apex position. However, after posterior-inferior capsular plication, the humeral head apex was significantly shifted inferiorly (P = .005) and anteriorly (P = .03) in maximum internal rotation compared with the intact state.

CONCLUSION

Significant changes in glenohumeral motion occur in this model during the simulated late-cocking and follow-through phases of throwing. In this model, posterior capsular tightness alters the humeral head position most profoundly during the deceleration and follow-through phases of throwing.

MR Imaging of Rotator Cuff Injury: What the Clinician Needs to Know

The rotator cuff muscles generate torque forces to move the humerus while acting in concord to produce balanced compressive forces to stabilize the glenohumeral joint. Thus, rotator cuff tears are often associated with loss of shoulder strength and stability, which are crucial for optimal shoulder function. The dimensions and extent of rotator cuff tears, the condition of the involved tendon, tear morphologic features, involvement of the subscapularis and infraspinatus tendons or of contiguous structures (eg, rotator interval, long head of the biceps brachii tendon, specific cuff tendons), and evidence of muscle atrophy may all have implications for rotator cuff treatment and prognosis. Magnetic resonance imaging can demonstrate the extent and configuration of rotator cuff abnormalities, suggest mechanical imbalance within the cuff, and document abnormalities of the cuff muscles and adjacent structures. A thorough understanding of the anatomy and function of the rotator cuff and of the consequences of rotator cuff disorders is essential for optimal treatment planning and prognostic accuracy. Identifying the disorder, understanding the potential clinical consequences, and reporting all relevant findings at rotator cuff imaging are also essential.

The effect of arm position on stretching of the supraspinatus, infraspinatus, and posterior portion of deltoid muscles: a cadaveric study

BACKGROUND

The stretching of the supraspinatus and infraspinatus muscles is important to prevent shoulder injuries. Although several authors have advocated various stretching techniques, a general opinion has not been reached owing to the lack of quantitative analysis.

METHODS

Nine fresh cadaveric shoulders were used to measure the strain on the supraspinatus, the middle and inferior portions of the infraspinatus, and the posterior portion of the deltoid muscles during eleven arm positions. The strain on the muscles was measured by precise displacement sensors attached to the center of each muscle belly.

FINDINGS

In case of the supraspinatus muscle, abduction at extension showed significantly larger strain than that in the neutral position (P < 0.05). Internal rotation at extension showed significantly larger strain in the middle portions of the infraspinatus (P < 0.05). Internal rotation at 30 degrees and 60 degrees elevation as well as extension showed significantly larger strain in the inferior portion of the infraspinatus (P<0.05). Adduction at 60 degrees elevation did not show large strain in the infraspinatus muscle; however, significantly larger strain was observed in the posterior portion of the deltoid muscle.

INTERPRETATION

Shoulder stretching techniques that are based on these experimental data can enhance the selective stretching of the corresponding muscles. Application of these techniques is considered to be useful for the prevention and treatment of shoulder injuries.

Plyometric exercise in the rehabilitation of athletes: physiological responses and clinical application

Plyometric exercise was initially utilized to enhance sport performance and is more recently being used in the rehabilitation of injured athletes to help in the preparation for a return to sport participation. The identifying feature of plyometric exercise is a lengthening of the muscle-tendon unit followed directly by shortening (stretch-shortening cycle). Numerous plyometric exercises with varied difficulty and demand on the musculoskeletal system can be implemented in rehabilitation. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels. The progression to higher-intensity plyometric exercise is thought to resolve postinjury neuromuscular impairments and to prepare the musculoskeletal system for rapid movements and high forces that may be similar to the demands imposed during sport participation, thus assisting the athlete with a return to full function. While there is a large body of scientific literature that supports the use of plyometric exercise to enhance athletic performance, evidence is sparse regarding the effectiveness of plyometric exercise in promoting a quick and safe return to sport after injury. This review will describe the mechanisms involved in plyometric exercise, discuss the considerations for implementing plyometric exercise into rehabilitation protocols, examine the evidence supporting the use of plyometric exercises, and make recommendations for future research.

Glenohumeral range of motion deficits and posterior shoulder tightness in throwers with pathologic internal impingement

BACKGROUND

Alterations in glenohumeral range of motion, including increased posterior shoulder tightness and glenohumeral internal rotation deficit that exceeds the accompanying external rotation gain, are suggested contributors to throwing-related shoulder injuries such as pathologic internal impingement. Yet these contributors have not been identified in throwers with internal impingement.

HYPOTHESIS

Throwers with pathologic internal impingement will exhibit significantly increased posterior shoulder tightness and glenohumeral internal rotation deficit without significantly increased external rotation gain.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

Eleven throwing athletes with pathologic internal impingement diagnosed using both clinical examination and a magnetic resonance arthrogram were demographically matched with 11 control throwers who had no history of upper extremity injury. Passive glenohumeral internal and external rotation were measured bilaterally with standard goniometry at 90 degrees of humeral abduction and elbow flexion. Bilateral differences in glenohumeral range of motion were used to calculate glenohumeral internal rotation deficit and external rotation gain. Posterior shoulder tightness was quantified as the bilateral difference in passive shoulder horizontal adduction with the scapula retracted and the shoulder at 90 degrees of elevation. Comparisons were made between groups with dependent t tests (P < .05).

RESULTS

The throwing athletes with internal impingement demonstrated significantly greater glenohumeral internal rotation deficit (P = .03) and posterior shoulder tightness (P = .03) compared with the control subjects. No significant differences were observed in external rotation gain between groups (P = .16).

CLINICAL RELEVANCE

These findings could indicate that a tightening of the posterior elements of the shoulder (capsule, rotator cuff) may contribute to impingement. The results suggest that management should include stretching to restore flexibility to the posterior shoulder.

Clinical Measures of Shoulder Mobility in College Water-Polo Players

Context:

Overhead stress from both swimming and throwing in water-polo players might lead to alterations in shoulder mobility and subsequent injury.

Objective:

To evaluate clinical measures of shoulder mobility in college water-polo players.

Design:

Repeated measures.

Setting:

University athletic training facility.

Patients:

31 Division I water-polo athletes.

Main Outcome Measures:

Measures were obtained for both the dominant and nondominant shoulders. Scapular upward rotation was measured using a digital inclinometer, posterior shoulder tightness was assessed by recording horizontal adduction with the scapula stabilized, and passive isolated glenohumeral-joint internal- and external-rotation range of motion were measured using goniometry.

Results:

No significant difference was observed between sides for scapular upward rotation (P= .68), posterior shoulder tightness (P= .25), or internal rotation (P= .41). A significant difference between sides was present for external rotation (P< .0001) and total arc of motion (P= .039).

Conclusions:

The dominant shoulders demonstrated significantly greater external rotation and a significantly greater total arc of motion than the nondominant shoulders did.

Alterations in Upper Extremity Motion after Scapular-Muscle Fatigue

Objective:

To determine the effect of scapular fatigue on shoulder and elbow kinematics and accuracy.

Design:

Pretest–posttest.

Setting:

Laboratory.

Participants:

30 healthy men.

Interventions:

Subjects performed seated overhead throws into a target before and after a standardized scapular-muscle-fatigue protocol.

Main Outcome Measurements:

Shoulder and elbow kinematic data were analyzed during throwing. Scapular upward rotation was measured (0°, 45°, and 90° humeral elevation in scaption) with an inclinometer. Throwing accuracy was measured as mean error distance from the target (cm).

Results:

After fatigue, there was a significant increase in total elbow motion (12 % more in cocking phase,P< .05) and elbow velocity in the follow-through phase (average and maximum into flexion,P< .05). Throwing accuracy decreased 26% after fatigue (P< .05).

Conclusions:

Scapular-muscle fatigue results in compensatory motions at the elbow that might affect performance and contribute to elbow pathologies.

Glenohumeral Range of Motion and Stiffness in Professional Baseball Pitchers

PURPOSE

This study was conducted to perform kinematic measures in a group of asymptomatic professional baseball pitchers to determine side-to-side differences in passive glenohumeral range of motion (ROM) and stiffness. We hypothesized that the throwing shoulder in asymptomatic pitchers would display greater passive glenohumeral stiffness than the contralateral nonthrowing shoulder.

METHODS

Thirty-four professional baseball pitchers had bilateral assessments for passive glenohumeral ROM and stiffness during a single test session. ROM and stiffness measures were obtained objectively using standard goniometry and instrumented stress arthrometry, respectively.

RESULTS

The throwing shoulder had significantly less (-8.5 degrees) internal rotation and significantly more external rotation (5.1 degrees) than the nonthrowing shoulder (P < 0.01). Passive joint stiffness was not significantly different between the throwing and nonthrowing shoulder, and anterior joint stiffness was significantly greater than posterior joint stiffness for both shoulders (P < 0.05).

CONCLUSIONS

The repetitive stress of long-term throwing creates altered glenohumeral rotational patterns in the throwing shoulder of the professional baseball pitcher without compromising the joint's passive restraining quality.

Factors correlated with volleyball spike velocity

BACKGROUND

Spike effectiveness represents a determining element in volleyball. To compete at a high level, the player must, in particular, produce a spike characterized by a high ball velocity.

HYPOTHESIS

Some muscular and physical features could influence ball velocity during the volleyball spike.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 19 male volleyball players from the 2 highest Belgian national divisions underwent an isokinetic assessment of the dominant shoulder and elbow. Ball velocity performance (radar gun) during a spike test, morphological feature, and jump capacity (ergo jump) of the player were measured. We tested the relationship between the isokinetic parameters or physical features and field performances represented by spike velocity. We also compared first-division and second-division player data.

RESULTS

Spike velocity correlated significantly with strength performance of the dominant shoulder (internal rotators) and of the dominant elbow (flexors and extensors) in the concentric mode. Negative correlations were established with the concentric external rotator on internal rotator ratio at 400 deg/s and with the mixed ratio (external rotator at 60 deg/s in the eccentric mode on internal rotator at 240 deg/s in the concentric mode). Positive correlations appeared with both the volleyball players' jump capacity and body mass index. First-division players differed from second-division players by higher ball velocity and increased jump capacity.

CONCLUSION

Some specific strength and physical characteristics correlated significantly with spike performance in high-level volleyball practice.

CLINICAL RELEVANCE

Our results could provide useful information for training management and propose some reflections on injury prevention.

Correlation of range of motion and glenohumeral translation in professional baseball pitchers

BACKGROUND

Altered mobility patterns in the throwing shoulders of professional baseball pitchers have been reported. Most published reports examining glenohumeral laxity have not used an objective testing device.

OBJECTIVE

Quantify and compare glenohumeral translation and rotational range of motion between the throwing and non-throwing shoulders in professional baseball pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Force-displacement and range of motion measures were performed bilaterally on 43 asymptomatic professional baseball pitchers. Ultrasound imaging was used to measure glenohumeral translations under stressed and unstressed conditions.

RESULTS

No significant difference in translation was found between the throwing and nonthrowing shoulders. For both shoulders, posterior translation (5.38 +/- 2.7 mm) was significantly greater (P < .001) than was anterior translation (2.81 +/- 1.6 mm). External rotation in the throwing shoulder was significantly greater than that in the nonthrowing shoulder (P < .001), whereas internal rotation in the throwing shoulder was significantly less than that in the nonthrowing shoulder (P < .001). The total arc of rotation for the throwing shoulder was not significantly different than that for the nonthrowing shoulder, and correlation coefficients were poor between rotational and translational range of motion in the throwing shoulder, ranging from r = 0.232 to 0.209 between variables.

CONCLUSION

No significant difference in glenohumeral translation exists between the throwing and nonthrowing shoulders in asymptomatic professional baseball pitchers, posterior translation is significantly greater than anterior translation in the throwing shoulders of professional baseball pitchers, and glenohumeral translation is not related to rotational range of motion in the throwing shoulders of professional baseball pitchers.

CLINICAL RELEVANCE

Altered mobility patterns in asymptomatic professional baseball pitchers may be due to factors other than capsular adaptive changes.

A cadaveric model of the throwing shoulder: a possible etiology of superior labrum anterior-to-posterior lesions

BACKGROUND

It has been speculated that a shift of the throwing arc commonly develops in athletes who perform overhead activities, resulting in greater external rotation and decreased internal rotation caused by anterior capsular laxity and posterior capsular contracture, respectively. Osseous adaptation in the form of increased humeral and glenoid retroversion may provide a protective function in the asymptomatic athlete but cannot explain the pathological changes seen in the shoulder of the throwing athlete. Therefore, the objective of the present study was to examine the biomechanical effects of capsular changes in a cadaveric model.

METHODS

Ten cadaveric shoulders were tested with a custom shoulder-testing device. Humeral rotational range of motion, the position of the humerus in maximum external rotation, and glenohumeral translations in the anterior, posterior, superior, and inferior directions were measured with the shoulder in 90 degrees of abduction. Translations were measured with the humerus secured in 90 degrees of external rotation. To simulate anterior laxity due to posterior capsular contracture, the capsule was nondestructively stretched 30% beyond maximum external rotation with the shoulder in 90 degrees of abduction. This was followed by the creation of a 10-mm posterior capsular contracture. Rotational, humeral shift, and translational tests were performed for the intact normal shoulder, after anterior capsular stretching, and after simulated posterior capsular contracture.

RESULTS

Nondestructive capsular stretching resulted in a significant increase in external rotation (average increase, 18.2 degrees 2.1 degrees ; p < 0.001), and subsequent simulated posterior capsular contracture resulted in a significant decrease in internal rotation (average decrease, 8.8 degrees +/- 2.3 degrees ; p = 0.02). There also was a significant increase in anterior translation with the application of a 20-N anterior translational force after nondestructive capsular stretching (average increase, 1.7 +/- 0.3 mm, p = 0.0006). The humeral head translated posteroinferiorly when the humerus was rotated from neutral to maximum external rotation. This did not change significantly in association with anterior capsular stretching. Following simulated posterior capsular contracture, there was a trend toward a more posterosuperior position of the humeral head with the humerus in maximum external rotation in comparison with the position in the stretched conditions, although these differences were not significant.

CONCLUSIONS

A posterior capsular contracture with decreased internal rotation does not allow the humerus to externally rotate into its normal posteroinferior position in the cocking phase of throwing. Instead, the humeral head is forced posterosuperiorly, which may explain the etiology of Type-II superior labrum anterior-to-posterior lesions in overhead athletes.

The college athlete

Participation in sports is important to many college students. Student athletes come from different levels of previous sport experience as they enter collegiate athletics. The primary source of student medical care is the campus student health center. The health care providers at student health centers attend to many of the sports-related concerns of student athletes. Preparticipation evaluation provides an opportunity to assess the general health of the student athlete and to identify conditions that might increase the risk of further injury. Sudden cardiac death and sports-associated concussions have generated much interest and are reviewed in this article. Other areas reviewed here include use of drugs and supplements, ankle sprains, acute knee ligament injuries, back pain, and shoulder impingement syndrome.

Development of cadaveric models of a thrower's shoulder

Two novel cadaveric models of a thrower's shoulder were evaluated. Both models included the capsuloligamentous and osseous components of the glenohumeral joint. In model 1 the coracohumeral ligament was retained and the glenoid was positioned parallel to the ground whereas the humerus was positioned at 60 degrees of glenohumeral elevation in the scapular plane. In model 2 the coracohumeral ligament was resected and the glenoid was positioned vertically at 30 degrees of scapular elevation whereas the humerus was positioned at 60 degrees of glenohumeral elevation in the scapular plane. Each specimen was sequentially tested under 3 conditions: intact, after nondestructive anterior capsular stretch, and after simulated posterior capsular contracture. Measurements included rotational range of motion and relative glenohumeral position from neutral to maximum external rotation of the humerus. In model 2 the glenohumeral forces were also measured by use of a 6-degree-of-freedom load cell. The stretching of the anterior capsule in model 1 was performed while the humeral head was constrained in the glenoid and in model 2 while the humeral head was unconstrained. Both models showed increased humeral external rotation and decreased humeral internal rotation similar to that seen in throwing athletes. Both models also showed an increased humeral shift inferiorly after anterior capsular stretching. Model 1 demonstrated a subsequent humeral shift superiorly after posterior capsule plication. Unconstrained specimens of model 2 dislocated posteriorly and inferiorly after posterior capsule plication when the humerus was rotated to maximum external rotation. On the basis of these findings, for future studies, constrained capsular stretching models will be further investigated.

Shoulder instability

Shoulder instability can result from acute injury or repetitive overhead activity. Once the injury is identified, the initial course of treatment is aggressive rehabilitation. Structural injuries can occur but may not be clinically significant. Should a thorough scapular stabilization and rotator cuff strengthening program fail, consultation with an orthopedic surgeon to consider further imaging or possible intervention is appropriate. As the physician's study of approaches to the first-time dislocator continues, they will be better informed of reasonable options to offer the athlete.

Sport-specific shoulder injuries

This article reviews basic shoulder anatomy and biomechanics and discusses the impact these have on the etiology of shoulder injuries in sports. Four types of sport activities lead to shoulder injuries:muscle and tendon overuse, acute tears of the dynamic stabilizers,impingement and overuse injury. Most shoulder injuries initially are treated nonoperatively with rehabilitation. Rehabilitation protocols are successful in most patients. This article also discusses why postoperative rehabilitation is vital to the ultimate success of patients who require operative treatment.

Postoperative shoulder rehabilitation

This article focuses on the rehabilitation considerations for several shoulder surgeries: acromioplasty, rotator cuff repair, rotator cuff debridement, Bankart repair, thermal capsulorrhaphy, superior labral anterior posterior repair, multidirectional instability, proximal humerus fracture, surgical management of the stiff shoulder, arthroplasty,and fusion. General guidelines are presented for discussing and planning rehabilitation for patients, including exercises, timing of progression, patient education, precautions or restrictions, and expectations.

Electromyographic analysis of the rotator cuff and deltoid musculature during common shoulder external rotation exercises

STUDY DESIGN

Prospective single-group repeated-measures design.

OBJECTIVES

To quantify electromyographic (EMG) muscle activity of the infraspinatus, teres minor, supraspinatus, posterior deltoid, and middle deltoid during exercises commonly used to strengthen the shoulder external rotators.

BACKGROUND

Exercises to strengthen the external rotators are commonly prescribed in rehabilitation, but the amount of EMG activity of the infraspinatus, teres minor, supraspinatus, and deltoid during these exercises has not been thoroughly studied to determine which exercises would be most effective to achieve strength gains.

METHODS AND MEASURES

EMG measured using intramuscular electrodes were analyzed in 10 healthy subjects during 7 shoulder exercises: prone horizontal abduction at 100 degrees of abduction and full external rotation (ER), prone ER at 90 degrees of abduction, standing ER at 90 degrees of abduction, standing ER in the scapular plane (45 degrees abduction, 30 degrees horizontal adduction), standing ER at 0 degrees of abduction, standing ER at 0 degrees of abduction with a towel roll, and sidelying ER at 0 degrees of abduction. The peak percentage of maximal voluntary isometric contraction (MVIC) for each muscle was compared among exercises using a 1-way repeated-measures analysis of variance (P<.05).

RESULTS

EMG activity varied significantly among the 7 exercises. Sidelying ER produced the greatest amount of EMG activity for the infraspinatus (62% MVIC) and teres minor (67% MVIC). The greatest amount of activity of the supraspinatus (82% MVIC), middle deltoid (87% MVIC), and posterior deltoid (88% MVIC) was observed during prone horizontal abduction at 100 degrees with full ER.

CONCLUSIONS

Results from this study provide initial information to develop rehabilitation programs. It also provides information helpful for the design and conduct of future studies.

Functional Neuromuscular Rehabilitation of Posterior Shoulder Dislocation in a High School Baseball Player

Posterior glenohumeral dislocations are rare, comprising only 4 percent of all shoulder dislocations. While early and accurate diagnosis of a posterior dislocation increases the likelihood of success with non-operative management, traditional rehabilitation may not adequately address the sensorimotor deficits that are evident following dislocation. Restoration of the sensorimotor system is critical to successfully return a throwing athlete safely to sports. The use of functional neuromuscular rehabilitation (FNR) attempts to address deficits in the compromised sensorimotor system. With a good understanding of the specific demands placed on the overhead athlete’s shoulder, knowledge of glenohumeral and scapulothoracic joints’ biome-chanics, respect for the athlete’s level of symptoms and pain, adherence to soft tissue healing, and application of a rehabilitation program that incorporates FNR, an athlete can successfully return to a high level of competition following an acute posterior glenohumeral dislocation.