Arm In External Rotation Research Articles

Isokinetic Peak Torque Improvement and Shoulder Muscle Ratios Imbalance Correction After Specific Strength Training on a New Ballistic Throwing Device: A Randomized Controlled Trial.

The aim of this study was to investigate the effects of 8-week ballistic-strength-training program using a validated specific throwing device (ie,Arm/Shoulder Specific Strength Device), on isokinetic shoulders' rotation muscle-torques and ratios as well as range of motion in team handball players. A repeated-measures experimental design with a randomized controlled trial was used. Twenty-six high-level competitive male U-19 team handball players were randomly assigned into training (TG, n = 15) and control (n = 11) groups. The TG undertook a twice a week for 8-week periodized throws program with an individually predetermined optimal load. The program incorporated shackled eccentric and concentric exercises using the Arm/Shoulder Specific Strength Device. Peak torques, functional, and conventional ratios for both arms at different angular velocities (60°·s-1, 180°·s-1, and 300°·s-1) were assessed over time and between groups, using an isokinetic dynamometer. A significant improvement for TG (P < .01; d = 1.13 [moderate]; +20.2%) of the concentric peak torques for dominant arm in external rotation was observed at 300°·s-1. Significant (P < .05-.01) increases were also noted for nondominant arm at the 3 studied angular velocities. In addition, 300°·s-1 eccentric peak torques of the dominant arm and nondominant arm have significantly improved for both external and internal rotations (P < .05; d = .99 [moderate] and d = 1.21 [large]; +15.7% and + 17.9%, respectively) with small changes at the other angular assessed velocities. Posttraining, TG's dominant arm showed significant improvements (P < .05-.01) in functional and conventional ratios at all velocities. Notably, significant differences (P < .05-.01) were observed at 60°·s-1 and across all velocities when comparing the TG with the control group. TG showed significant increase for internal rotation and external rotation shoulder range of motions (P < .05; d = 1.22-1.27 [large]), +5.0% and +7.7%, respectively). The specific 8-week throwing training program on the Arm/Shoulder Specific Strength Device showed significant performance improvements in almost all assessed isokinetic concentric and eccentric peak torques as well as internal and external range of motion increase for both arms while ensuring rotator cuff torque ratios and shoulder mobility in team handball real sport-specific condition.

Surgical Technique for the Latarjet Procedure Using Non-Cannulated Screws

Background: The Latarjet procedure is effective for patients with anterior glenohumeral instability with substantial glenoid bone loss due to its triple blocking effect. Indications: Indications include high-risk patients with recurrent anterior glenohumeral instability with any glenoid bone loss or low-risk patients with 15% to 30% glenoid bone loss. Technique Description: An incision is made lateral to the coracoid and the deltopectoral interval is established. The pectoralis minor is released medially off the coracoid and the coracoacromial (CA) ligament is released close to the acromion. The coracoid is cut with a right-angle saw and the inferior coracoid is decorticated with a burr. Two holes are pre-drilled in the coracoid. The subscapularis is split between the upper two-thirds and lower one-third with the arm in external rotation. The capsule is split vertically at the joint line and the humeral head is retracted. The anterior glenoid is decorticated with a burr, and a hole is drilled inferiorly. The depth is measured and added to the depth of the inferior bone block hole. A fully threaded 3.5-mm solid stainless steel screw is placed in the inferior hole. Care is taken to ensure that the lateral border of the bone block is flush with the articular margin. This is repeated for the superior hole. A 1.8-mm knotless suture anchor is placed between the screws. The repair stitch is passed through the capsule and loaded onto the anchor and tensioned. The CA ligament is laid over the capsule and repaired. The subscapularis split is repaired side to side and the wound is closed in layers. Results: High return-to-sport rates, including at the same level of play, have been observed among young competitive athletes with significant glenoid bone loss who underwent a Latarjet, with similarly favorable results in older patients. Ninety-day complication rates have been reported around 9%, 5% of which constituted graft or hardware failures. Discussion/Conclusion: The Latarjet procedure is an effective option for indicated patients with anterior glenohumeral instability and may be enhanced with solid screws, proper anatomic technique, and capsulolabral repair augmentation. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Shoulder muscle activation during scapular protraction exercise with arm rotation.

The role of the serratus anterior is to maintain scapular stability. To strengthen this muscle, scapular protraction exercises are typically performed. Although the angle of arm rotation leads to changes in shoulder muscle activation, the arm rotation position is not normally determined. To investigate if scapular muscle activations were changed by combining arm external rotation during scapular protraction exercises. Thirty-four healthy men were enrolled in this study. Participants were instructed to perform scapular protraction exercises at 90∘ and 120∘ of shoulder flexion while in the standing and supine positions. Two different arm rotation angles were used: the thumb-up position (neutral position) and the maximum arm external rotation (ER) position. The percentages of maximum voluntary contractions (%MVCs) were measured, and %MVCs in the neutral and arm ER positions were compared. Muscle activities of the middle serratus anterior (MSA) and lower serratus anterior (LSA) in the arm ER position were significantly higher than those in the neutral position during all tasks. The highest MSA and LSA positions were observed with the arm ER position of 120∘ while standing. Scapular protraction exercises with arm ER resulted in a higher serratus anterior activity.

Open Reduction and Internal Fixation of Pediatric Medial Epicondylar Humeral Fractures in the Prone Position.

Fracture of the medial epicondyle is a common pediatric injury, with an estimated annual incidence of 40 to 60 per 100,000 people per year1-3. Medial epicondylar fractures are associated with elbow dislocation in about 60% of cases, and ulnar nerve dysfunction is reported to occur nearly 10% of the time2,4. No standard of care for medial epicondylar fracture exists, as similar outcomes have been demonstrated in observational studies with both operative and nonoperative treatment5,6. Increasingly, however, these injuries are being treated with surgical intervention, which in most cases consists of a single screw affixing the osseous piece back to its donor site on the humerus7-9. There is broad consensus on the absolute indications for operative treatment, including an open fracture and an incarcerated epicondylar fragment1,10-13. The relative indications are more controversial and include ulnar nerve dysfunction, elbow instability, increased fragment displacement, and high-level throwing or upper-extremity weight-bearing athletes2,9,14-16. The patient is placed in the prone position with the operative arm on a radiolucent arm board. A milking maneuver with an Esmarch bandage is utilized. A posteromedial incision is made over the medial epicondyle. The ulnar nerve is protected posteriorly. The fracture is easily reduced under minimal tension, and then 1 or 2 guidewires from the 4.0-mm cannulated screw kit are placed to fix the fragment. The central guidewire is overreamed, and then a partially threaded 4.0-mm screw is placed in a relative posterior-to-anterior trajectory within the medial column of the elbow. Nonoperative treatment includes immobilization in a long arm cast until fragment healing. Complications associated with nonoperative treatment include nonunion and late instability. Supine positioning is a reasonable alternative to the prone position described here. In that case, the fracture is fixed with the arm in external rotation of the shoulder and with the elbow extended. Prone positioning for operative treatment of medial epicondylar fractures is preferred because the tension from the flexor pronator mass associated with supine positioning is negated, facilitating an easier fracture reduction and improved anatomic reduction. To our knowledge, there are currently no Level-I or Level-II prospective studies reporting on the outcomes of operative versus nonoperative treatment of medial epicondylar fractures. A systematic review of retrospective results suggested no difference in pain or clinical outcomes, but >9-times greater odds of union with operative treatment5,6. Expectations following operative treatment of a medial epicondylar fracture have been explored in multiple studies. Generally, return to full levels of activity and near-normal range of motion of the elbow have been demonstrated by most. Minor rates of range-of-motion limitation, including extension deficit (4% with deficit up to 20°) are reported in some studies8. In the setting of preoperative instability, the expectation is that elbow stability will be achieved by operative treatment7,8. Perform and document an accurate preoperative neurovascular examination of the arm.Test the shoulder in internal rotation prior to prone positioning.Protect the ulnar nerve during surgical fixation and drilling.Confirm that the screw trajectory is relatively posterior to anterior and only in the medial column of the elbow.

In vivo measurement of distance between scapular neck and polyethylene insert during active external rotation in shoulders with Grammont type reverse prosthesis

BackgroundScapular notching is a frequently observed complication after reverse shoulder arthroplasty. Impingement of the humeral plastic insert against the scapular neck is believed to be the cause of notching. There have been no in vivo studies that analyzed the positional relationship between the scapular neck and humeral insert. The purpose of this study was to measure the distance between the scapular neck and insert in shoulders with Grammont-type prostheses during active external rotation at the side. MethodsEighteen shoulders with Grammont-type prostheses were enrolled in this study. There were 13 males and 5 females, and the mean age at surgery was 74 years (range, 63–91). Fluoroscopic images were recorded during active external rotation at the side from maximum internal to external rotation at an average of 14 months (range, 7–24) after surgery. Implant kinematics were determined with three-dimensional models of the implants and fluoroscopic images using model-image registration techniques. Based on the implant kinematics, the closest distance between the scapular neck and insert was computed at each 5° increment of glenohumeral internal/external rotation. ResultsMean glenohumeral abduction during rotation was 17°–22°. The mean distance between the neck and insert was approximately 1 mm throughout the activity. The separation distance tended to narrow with arm external rotation, but the change was not significant. InterpretationThe small distance between the scapular neck and insert in early post-operative reverse shoulder arthroplasty patients may be associated with the high incidence of scapular notching in Grammont-type prostheses.

FUNCTIONAL OUTCOME OF MODIFIED PUTTI PLATT PROCEDURE IN RECURRENT DISLOCATION OF SHOULDER – A RETROSPECTIVE ANALYSIS

Hand, which is considered to be an extension of brain and a tool for the execution of human intellect and will, owes much to the versatility of the movement of the shoulder for its placement on the desired spot of action. The shoulder, by virtue of its anatomy and biomechanics, is one of the most unstable and frequently dislocated joints, accounting for nearly 50% of all dislocations. Most of the recurrent dislocations of shoulder (96%) follow an initial signicant traumatic dislocation. There are two basic types of surgical approaches for shoulders with anterior instability: "anatomic" and "non-anatomic" repairs. With anatomic repairs, the goals are to restore the labrum toits normal position and to reestablish the appropriate tension in the shoulder capsule and ligaments. The goal of non-anatomic surgical procedures is to stabilize the shoulder by compensating for the capsulolabral and osseous injury with an osseous or soft-tissue checkrein that blocks excessive translation and restores stability. In Modied Putti Platt procedure, as done in our institute, after proper positioning and adequate exposure, the subscapularis muscle and capsule is incised at the musculotendinous junction. Aquadrangular unicortical graft, harvested from the iliac crest, is inserted fully into the trough made in the anterior glenoid, resulting in deepening of the glenoid articular surface. Subscapularis and the capsule are closed by double breasting, keeping the arm in external rotation. We did a retrospective analysis to assess the outcome of this procedure done in our institute. 102 patients were assessed and the required data were collected using hospital medical records, telephonic interview and direct clinicoradiological assessment. All the patients had positive apprehension test, pre- operatively. The mean Rowe score was 30.98 (standard deviation 5.846). The mean follow up duration was 44.52 months. 91 patients (89.2%) had no pain at last follow up duration and the rest had slight and occasional pain. All the patients were able to work above shoulder. The mean external rotation at 6 months follow up was 37.89° (SD 9.239), which increased to 65.88° (SD 8.967) at last follow up. The mean internal rotation at 6 months follow up was 61.18° (SD 4.623), which increased to 77.16° (SD 6.234) at last follow up. There was signicant improvement of Rowe's score post-operatively when compared to pre-operative Rowe's score. There was a signicant mean increase of 49.216 points post operatively with a correlation coefcient of +0.513. (p&lt;0.05). All patients, at last follow up had a UCLA score of more than 27, with 96 patients (94.1%) had good clinical outcome (according to UCLA grading system). 6 patients had fair clinical outcome. 77 patients (75.5 %), according to Rowe score had good clinical outcome.12 patients (11.8%) had excellent outcome. 13 patients had fair clinical outcome. None of the patients who were operated in our institute had recurrence of dislocation. None of them were reoperated. 91 patients (89.2%) had negative apprehension with no evidence of subluxation. 10 patients (9.8%) had negative apprehension, but slight discomfort in abduction and external rotation. One person had positive apprehension test, but he was able to continue his activities of daily living and continued to engage in professional non contact sports, though at one level below; and he did not choose to undergo a reoperation. 6 patients, all aged more than 45 years, had clinicoradiological evidence of mild arthrosis of the shoulder joint. They are being treated conservatively with physical therapy and analgesics Mild donor site pain was there in 6 patients in the rst yr of surgery. This subsided with time with analgesics. None had evidence of donor site infection, and none had evidence of visceral injuries.

Comparison of Biomechanical Factors Before and After UCL Surgery in Baseball Athletes: A Systematic Review With Meta-analysis.

Background:Ulnar collateral ligament (UCL) reconstruction (UCLR) and repair (UCLr) are the gold standards in the treatment of UCL injuries. Although return-to-play timelines after UCLR have been established, pitching biomechanical variables are speculated to change after surgical intervention.Purpose/Hypothesis:To synthesize the literature and investigate changes in pitching biomechanics in baseball pitchers after UCLR or UCLr. We hypothesized that differences in pitching biomechanics would be observed for both intra- and interpatient comparisons.Study Design:Systematic review; Level of evidence, 3.Methods:We searched 4 electronic databases (PubMed, Web of Science, SCOPUS, and Sports Medicine & Education Index) from inception to February 2020. Data extracted included author and year of publication, study design, sample size, study population, and primary outcome variables. Meta-analysis was performed to produce random pooled effect sizes (▵).Results:We identified 1010 original articles for inclusion. A total of 5 studies were included in the systematic review; of these, 3 studies were included in the meta-analysis. No differences were found in shoulder range of motion (ROM) between post-UCLR and control pitchers (dominant arm external rotation ▵, 0.13°; 95% CI, –0.15° to 4.02°; P = .36); dominant arm internal rotation ▵, –0.20°; 95% CI, –0.74° to 0.35°; P = .48). Mean fastball velocity as well as pitches thrown decreased after UCLR in professional pitchers. Significant differences in elbow extension, elbow extension velocity, and shoulder internal rotation velocity were found among amateur pitchers.Conclusion:The results of this systematic review and meta-analysis show that limited differences exist in pitchers before and after UCLR as well as in post-UCLR pitchers and healthy, age-matched controls. UCLR may influence throwing velocity, but it had no effect on either the throwing biomechanics or theROM of baseball pitchers. Although trends appear to be forming, further evidence is needed to understand the effect of UCLR on throwing biomechanics.

Factors Affecting Stability of the Reverse Total Shoulder Arthroplasty: A Cadaveric Biomechanical Study

Background: The overall objective of this study was to investigate whether a reverse shoulder arthroplasty could provide adequate stability to a shoulder even with extreme soft tissue loss. The specific objectives of this study were: to determine if just the deltoid, conjoined tendon, and triceps are sufficient soft tissues to allow a Reverse Shoulder Arthroplasty (RSA) to provide shoulder stability and to determine the influence of load direction, rotation, shoulder position, and polyethylene thickness on RSA stability in this soft-tissue deficient model. Methods: This study utilized six cadaveric shoulders that had all soft tissue removed, with the exception of the deltoid, conjoint tendon, and long head of triceps. A reverse shoulder arthroplasty was then performed (Delta III, DePuy Inc., Warsaw, IN) and an increasing dislocation force was applied perpendicular to the humeral socket centerline until dislocation occurred, or a maximum load of 100 N was reached. This was repeated to measure the effect of four factors: load direction, arm position, polyethylene thickness, and arm rotation on force to dislocation. Results: For load direction, there was an increase in force to dislocate an inferior load direction (p=0.01). There was a lower not dislocated percentage and lower survival for a posterior load direction (p=0.02). For arm position, there was a decrease in force for dislocation and lower survival for both abduction and extension arm positions. There was a higher not dislocated percentage for a flexion arm position (p=0.01). For arm rotation, there was a lower not dislocated percentage and lower survival for an external rotation arm position (p=0.03). There was no statistically significant influence of polyethylene thickness (p=0.26). Conclusion: The deltoid, conjoined tendon, and triceps are sufficient to stabilize an RSA. Load direction, arm position, and arm rotation were all shown to significantly affect stability. Finally, polyethylene thickness may not affect overall RSA stability in this soft-tissue deficient model. Level of Evidence: Basic science study, Biomechanical study.

Immobilization in External Rotation Reduces the Risk of Recurrence After Primary Anterior Shoulder Dislocation: A Meta-analysis.

Background:The best method for nonsurgical treatment after primary dislocation of the shoulder is not clear. The efficacy of immobilization with the arm in external rotation (ER) compared with internal rotation (IR) remains controversial.Purpose:To determine the efficacy of ER immobilization versus IR immobilization on recurrence rate after primary dislocation of the shoulder from the evidence of randomized controlled trials.Study Design:Systematic review; Level of evidence, 2.Methods:Electronic databases (MEDLINE [Ovid SP], PubMed, Web of Science, EBM reviews, and CINAHL) and available proceedings according to the abstracts of major international meetings related to or including shoulder injuries and trauma were used to search for randomized controlled trials. Two independent investigators determined eligibility and carried out data extraction from the selected studies.Results:A total of 9 studies (817 patients) were selected for this meta-analysis. They included 668 male and 149 female patients, with a mean age ranging from 20.3 to 37.5 years. In the 9 pooled studies, the recurrence rate of shoulder dislocation was 21.5% (84/390) in the ER group versus 34.9% (130/373) in the IR group. ER immobilization significantly reduced the recurrence rate compared with IR immobilization (risk ratio, 0.56; P = .007). In the subgroup analysis of those immobilized full-time, ER immobilization was significantly more effective than IR immobilization in reducing the recurrence rate (risk ratio, 0.57; P = .01). In the subgroup analysis of age, ER immobilization was significantly more effective than IR immobilization in those aged 20 to 40 years but not in those younger than 20 years.Conclusion:This meta-analysis demonstrates that ER immobilization reduces the recurrence rate after primary shoulder dislocation compared with IR immobilization in patients older than 20 years. When treating a patient with primary shoulder dislocation, the clinician should provide this information to the patient before a treatment method is selected.

Profiling Shoulder Strength in Competitive Surfers.

The shoulder region has the highest incidence of acute injuries in the sport of surfing. Little is known about the strength profile at the shoulder in a surfing cohort. The primary aim of this study was to establish the reliability of a rotator cuff strength testing procedure for surfers with a secondary aim of providing a profile of internal and external rotation strength in a competitive surfing cohort. Shoulder internal rotation and external rotation isometric strength was measured using a hand-held dynamometer in 13 competitive surfers. Intra-class coefficient values ranged from 0.97 to 0.98 for intra-rater reliability and were lower for inter-rater reliability ranging from 0.80 to 0.91. Internal rotation strength was greater than external rotation strength bilaterally (dominant, p = 0.007, non-dominant, p < 0.001). No differences (p < 0.79) were found in internal rotation strength between the dominant and non-dominant arms. External rotation strength was weaker on the non-dominant arm compared with the dominant arm (p < 0.02). The non-dominant arm external rotation to internal rotation ratio (0.82 ± 0.15) was lower (p = 0.025) than the dominant arm (0.88 ± 0.14). The current procedure is reliable with the same clinician, and results indicate musculature asymmetry specific to the external rotators.

What is the best glenoid configuration in onlay reverse shoulder arthroplasty?

The purpose of this study was to analyze the effect of different glenoid configurations on arm position and range of motion (ROM) following reverse shoulder arthroplasty (RSA). The hypothesis was that different glenoid configurations would lead to changes in humeral offset, acromio-humeral distance (AHD), ROM, and rotator cuff muscle length. Using a three-dimensional (3D) computer model, implantation of an RSA was simulated with a 145° onlay humeral stem combined with five different glenoid configurations which varied in diameter and centre of rotation. Glenoid offset, the AHD, ROM, and muscle length were evaluated for each configuration. Changing glenoid design led to up to a 10mm change in offset and a 3mm change in the AHD. There was 7° of improvement in abduction and flexion between the different glenoid designs. Two of the configurations, the 36mm centered and the BIO-RSA, had an adduction deficit. In extension and external rotation arm with the arm at side, the eccentric 36mm glenosphere was the best configuration while the centered 36mm glenosphere was the worst configuration. The 42mm glenosphere limited external rotation at 90° of abduction. Varying the glenosphere configurations leads to ROM and muscle length changes following RSA. With a 145° onlay humeral stem, a 36 eccentric glenosphere theoretically optimizes ROM while limiting scapular notching.

Paediatric supracondylar humeral fractures: a technique for safe medial pin passage with zero incidence of iatrogenic ulnar nerve injury.

The cross Kirschner wire (K-wire) configuration in closed reduction and percutaneous pinning of paediatric supracondylar humeral fracture affords superior stability. However, medial pin placement presents a risk of iatrogenic ulnar nerve injury. This study describes, in step-by-step detail, another safe method of percutaneous medial pin insertion. The technique involved placing the patient's arm in external rotation, with elbow flexed no more than 45° after closed reduction. The surgeon held the K-wire close to its sharp end to pass it percutaneously onto the medial epicondyle, then adjusted his grip toward the blunt end. After fluoroscopy check, the wire driver was engaged and an anteriorly directed force was applied to the distal humerus fragment using the thumb of the surgeon's free hand. The K-wire was inserted at a 45° angle to the longitudinal axis of the humerus shaft. Clinical notes and radiographs of patients who underwent surgery with this technique from 2006 to 2008 were reviewed. A total of 125 patients (84 boys, 41 girls) were included, with a mean age of 7.1 (range 2-14) years. Most injuries were left-sided (72.8%, n = 91, vs. right: 27.2%, n = 34). 72 (57.6%) patients had two-pin cross K-wire configuration, while 53 (42.4%) patients had an additional lateral pin inserted. No patient had postoperative ulnar neuropathy. There were no complications of non-union, malunion or infection. This safe method of medial pin placement for surgical stabilisation of paediatric supracondylar humeral fractures is easily learnt and reproducible, and produces excellent results.

Libération capsulaire isolée arthroscopique pour l’enraidissement en rotation interne de l’épaule, séquelle de paralysie néonatale du plexus brachial. Résultats cliniques d’une cohorte prospective de 28 cas avec suivi de 2 ans

The limitations of shoulder mobility in external rotation and elevation are the most frequently observed late deficits in neonatal paralysis of brachial plexus. These limitations represent both a sequel (paralysis) and a complication (stiffness). Methods of shoulder release have enabled the possibility of recuperation of active mobility in external rotation. Recently, interest turned to arthroscopic procedures. Indications still remain unclear. The primary objective was to evaluate passive and active gain of external rotation in children with internal contraction, sequel brachial birth palsy after arthroscopic isolated capsular release. The secondary objective was to evaluate the passive and active gain of anterior elevation and internal rotation. This is a monocentric prospective study about the surgical procedure started in 2011. Inclusion criteria were any children over 2 years, with a limited range of motion of the shoulder secondary to brachial plexus birth palsy with active external rotation with elbow at side ≤ 30° and or active anterior elevation ≤ 90°. Non-inclusion criteria were a history of previous palliative surgery, and parents and or child who were reluctant to surgery. The same clinical evaluation was done preoperatively, at 6 weeks, 3 months, 6 months, 1 and 2 years of follow-up. Was noted the passive gleno-humeral, passive global (addition of gleno-humeral and scapulo-thoracic motion) and active global mobility movements for external rotation arm at side (ER1), anterior elevation (AE) and internal rotation arm at side (IR1). Mallet classification was used for functional assessment. Surgery was a capsulo-ligamentar release preserving subscapularis. Statistical analysis compared preoperative and 2 years follow-up values. Results Between 2011 and 2015, 35 patients were included and 28 completed the follow-up at 2 years. Active ER1 average gain was 35° (P

Force direction and arm position affect contribution of clavicular and sternal parts of pectoralis major muscle during muscle strength testing

Study DesignCross-sectional study. Purpose of the StudyThe study aims to determine the effects of force direction and arm position in differentiating the clavicular (PMc) and sternal (PMs) parts of the pectoralis major (PM) muscle during maximal voluntary isometric contraction (MVIC) to provide basic evidence to support the clinical thinking behind muscle strength testing of PM. MethodsNine experimental conditions with 3 force directions of horizontal adduction (+30° oblique, horizontal, and −30° oblique to the transverse plane) and 3 arm rotation positions (0°, 45°, and 90° shoulder external rotation from the transverse plane) were randomly tested for 26 healthy male participants. The MVIC force level was monitored and measured with a fixed dynamometer, and the surface electromyographic (EMG) signals of the PMc, PMs, anterior deltoid, middle deltoid, and latissimus dorsi were collected during the test for each condition. The PMc/PMs EMG ratio and normalized EMG amplitude were used to quantify the contribution of the tested muscles. ResultsThe MVIC force level significantly declined when the arm's external rotation increased (P < .01; the grand mean decreased from 106.7 N ± 27.8 N to 89.5 N ± 22.6 N). The PMc/PMs EMG ratio showed that the best test condition to differentiate the PMc and PMs was the force direction of +30° oblique to the transverse plane and the 45° arm rotation position. Other muscles contributed less than 40% of their MVIC activity levels, with a higher activation level found in the anterior deltoid muscle (P < .01). ConclusionsArm rotation position should be considered as a predominant factor when clinically examining the strength of horizontal adduction movement. All tested conditions failed to fully separate PMc and PMs activation during MVIC and suggested that functional differentiation of the PM might not be applicable to maximal exertion. Level of EvidenceNA.

Shoulder Muscle Activity in Sport Climbing in Naturally Chosen and Corrected Shoulder Positions

Objective:The aim of the study was to determine electromyographic activity of the scapula stabilizing muscles in naturally chosen and corrected shoulder positions in typical static climbing postures.Methods:Six male participants undertook surface electromyography measurement in four climbing postures for two different shoulder positions. The activity of the lower, middle and upper trapezius, serratus anterior, pectoralis major, and sternocleidomastoid was recorded. Electromyographic activity was expressed as the percentage of maximal voluntary contraction (MVC) for each muscle.Results:Climbing postures induced higher activation of middle and lower trapezius in corrected shoulder positions (35.3 ± 11.8 and 61.7 ± 15.4% MVC respectively) than in naturally chosen shoulder positions (18.4 ± 8.9 and 30.1 ± 13.8% MVC respectively). The highest activity of the middle and lower trapezius was found in postures with the arm in external rotation and 90° abduction and in an overhanging posture. Low activation was stated for the other muscles in both shoulder conditions.Conclusion:Results showed that climbers naturally elevate the shoulder during typical static postures. Corrected shoulder positions induce higher activation of the scapula stabilizing muscles than naturally chosen shoulder positions.

Preliminary clinical outcomes of Latarjet-Patte coracoid transfer by arthroscopy vs. open surgery: Prospective multicentre study of 390 cases

BackgroundThe Latarjet-Patte procedure consisting in transfer and screw fixation of the coracoid process to the anterior glenoid is a treatment of reference for anterior shoulder instability. Over time, surgical innovations translated into a number of improvements and, in late 2003, an arthroscopically assisted variant of the procedure was described. ObjectiveTo evaluate and compare clinical outcomes of the modified Latarjet-Patte procedure performed by open surgery, arthroscopy with screw fixation, or arthroscopy with endobutton fixation. Material and methodA total of 390 patients who underwent surgery to treat anterior shoulder instability between March 2013 and June 2014 were included and divided into three groups depending on whether they were managed using open surgery with screw fixation, arthroscopy with screw fixation, or arthroscopy with endobutton fixation. Clinical findings were recorded pre-operatively then 6 months post-operatively and at last follow-up (mean, 27.7 months). Range of motion and apprehension test (arm in external rotation at 0°, 90°, and 140° of abduction) were assessed and the Walch-Duplay and modified Rowe scores were determined. ResultsMotion range restriction was minimal with all three techniques, and motion range continued to improve throughout follow-up. Apprehension in external rotation was noted at 90° of abduction in 11% of cases and at 140° of abduction in 4% of cases. The mean total Walch-Duplay score improved from 46 pre-operatively to 90.6 and the mean total modified Rowe score from 46 pre-operatively to 91.1. By statistical analysis, external rotation at 90° of abduction and internal rotation at 0° of abduction were better after open surgery, but the differences were of limited clinical significance. Recurrence was noted in 3.3% of cases, nerve injury in 0.8%, and infection in 1.5%. ConclusionIn this study, the three techniques produced similar clinical outcomes, with a stable shoulder and no joint stiffness.

Correlation of the Rotator Interval on Direct CT Arthrography in Shoulder Instability Patients with External Rotation Stress Radiographs

The rotator interval (RI) is defined as the space between the anterior aspect of the supraspinatus tendon (SST) and superior aspect of the subscapularis tendon (SSC), covered by rotator interval capsule (RIC) (1, 2). It represents a region of capsule that is not reinforced by overlying rotator cuff tendon (1) and its components, coracohumeral ligament (CHL) and superior glenohumeral ligament (SGHL), are suggested to have a role in glenohumeral joint (GHJ) stability. The role of different shoulder stabilizers vary according to different shoulder position. For example, the CHL is shown to be a stabilizer in superior-inferior directions with arm in external rotation, whereas, the intra-articular pressure that is maintained by the intact RIC is suggested to act as a stabilizer in superior-inferior directions with the arm in internal and neutral rotations (3). The role of the RI in shoulder mechanopathology remains a much debated subject, with some authors advocating its role as a negative articular pressure inducer (3), whereas others, in resisting posteroinferior glenohumeral translation (4-7). Correlation of the Rotator Interval on Direct CT Arthrography in Shoulder Instability Patients with External Rotation Stress Radiographs 견관절 불안정 환자의 CT 관절 조영술상 회전근개 간격과 외회전 부하 영상과의 연관성

Throwing-related injuries of the subscapularis in professional baseball players.

To describe the MR appearance of a series of throwing-related injuries to the subscapularis muscle-tendon complex among baseball players. A retrospective review of MR scans of the shoulder in players from 1 professional baseball organization over the course of 5 years was performed to identify cases with findings suggestive of subscapularis injury. These findings were graded and the medical record was reviewed to assess clinical findings, treatment, and follow-up. Preinjury baseline measurements of arm external rotation at 90° of abduction were compared to measurements from a noninjured cohort to evaluate whether this measure is a risk factor for injury. A total of 133 MR scans of the shoulder were evaluated. Eleven of the scans demonstrated signal changes suggesting subscapularis injury; 10 of these 11 patients had clinical findings supporting a diagnosis of throwing-related subscapularis strain. There were four grade 1, four grade 2, and two grade 3 injuries. All injuries occurred in the inferior half of the subscapularis at the myotendinous junction. Risk of subscapularis injury increased with lower levels of dominant arm external rotation (odds ratio, 1.12; 95% CI, 1.07-1.21; p < 0.001). A threshold of dominant arm external rotation of <106° demonstrated sensitivity of 0.700 (95% CI, 0.392-0.897) and specificity of 0.951 (95% CI, 0.888-0.982) for subscapularis injury. Throwing-related subscapularis injuries occur in the inferior half of the muscle at the myotendinous junction. Our data suggest that there is an increased risk of these injuries with lower levels of dominant arm external rotation.

Throwing-Related Injuries of the Subscapularis in Professional Baseball Players

Objectives:Injuries to the shoulder are a common cause of missed playing time in professional baseball athletes. These injuries predominately involve the supraspinatus tendon or the glenoid labrum. The purpose of this project is to describe a series of throwing-related injuries to the subscapularis muscle-tendon complex that have been previously unreported amongst baseball players. Additionally, it is the goal to describe a mechanism of injury as well as a treatment program for these athletes.Methods:A retrospective review of shoulder magnetic resonance imaging (MRI) scans of players from 1 Major League Baseball organization over the course of 5 years was performed to identify cases with findings suggestive of a subscapularis injury. The MRIs were graded and the medical records were reviewed to assess clinical findings, treatment plans, and follow-up. In the injured cohort, preinjury baseline measurements of shoulder motion including external rotation at 90° of abduction were compared to measurements from a non-injured baseball athlete cohort to evaluate whether decrease external rotation is a risk factor for this injury.Results:A total of 133 MRI scans of the shoulder were evaluated. Eleven of the 133 MRIs demonstrated signal changes suggesting subscapularis injury. Ten of these 11 patients had clinical findings supporting a diagnosis of throwing-related subscapularis strain. There were 4 grade I, 4 grade II, and 2 grade III injuries. All injuries occurred in the inferior half of the subscapularis at the myotendinous junction. Risk of subscapularis injury increased with lower levels of dominant arm external rotation (odds ratio, 0.89; 95% CI, 0.82-0.94; P < .001). A threshold of dominant arm external rotation of less than 106° demonstrated sensitivity of 0.700 (95% CI, 0.392-0.897) and specificity of 0.951 (95% CI, 0.888-0.982) for subscapularis injury. All players were treated conservatively without surgery; only 1 did not return to play. Of the remaining players, the mean number of days missed because of injury was 27 (range, 11-61 days).Conclusion:Throwing-related subscapularis injuries occur in the inferior half of the muscle at the myotendinous junction. The subscapularis muscle fibers are oriented along a fan shape because of the relatively narrow insertion on the lesser tuberosity of the proximal humerus and a broader origin on the scapula with muscle fiber alignment dependent on arm position. When the thrower's arm is at 90 degrees of abduction and external rotation, the inferior fibers of the subscapularis comes to be aligned in the transverse plane across the glenohumeral joint and are placed on greatest stretch during the late cocking and early acceleration phases of throwing. Our data suggest that there is an increased risk of these injuries with lower levels of dominant arm external rotation as this shorter arc requires greater force production by the subscapularis muscle to achieve the same peak throwing velocity.

Alterations of Muscular Strength and Left and Right Limb Balance in Weightlifters after an 8-week Balance Training Program

[Purpose] Balance is generally defined as the ability to maintain the body's center of gravity within its base of support and may be categorized by either static or dynamic balance. The purpose of the present study was to evaluate the effect of 8 weeks of balance training on strength, and the functional balance ability of elite weightlifters. [Subjects] Thirty-two elite weightlifters were recruited for the present study. They were divided into exercise groups (8 high school students, 8 middle school students) and control groups (8 high school students, 8 middle school students). [Methods] Body compositions were measured by the electrical impedance method, and a Helmas system was used to measure basic physical capacities. The muscular function test was conducted using a Cybex 770. [Results] There were no significant changes in body composition after the training. In contrast, significant changes were found in the number of push-ups, one-leg standing time with eyes closed, and upper body back extension. Interestingly, only the left arm external rotation value after the exercise training program showed a statistically significant difference from the baseline value. [Conclusion] The peak torque values of shoulder internal rotation and knee extension were significantly changed compared to the baseline values, which mean subjects showed balance of their muscular power. Therefore, the results of the present study suggest that an 8-week balance-training program would positively affect elite weightlifters' balance ability and flexibility. We think that well-balanced muscular functionality may enhance athletes' sport performance.