Maximum External Rotation Research Articles

Single-bundle ACL reconstruction with and without extra-articular reconstruction: evaluation with robotic lower leg rotation testing and patient satisfaction scores.

PurposeThe purpose of this study was to compare the biomechanical characteristics and patient outcomes after either isolated intraarticular ACL reconstruction or intraarticular reconstruction with lateral extra-articular tenodesis. In addition, we aimed to evaluate biomechanical parameters of the entire uninjured, contralateral knee as a baseline during the analysis.MethodsEighteen patients were evaluated at an average of 9.3 years after ACL reconstruction. Twelve patients had an intraarticular reconstruction (BTB), and six had an additional lateral extraarticular procedure (BTB/EAR). Patients were selected for the additional procedure by the operating surgeon based on clinical and radiological criteria. At the time of review, each patient was assessed using subjective patient questionnaires, manual laxity testing, and instrumented laxity testing. Each knee was also evaluated using a robotic lower leg axial rotation testing system. This system measured maximum internal and external rotations at 5.65 Nm of applied torque and generated load deformation curves and compliance data. Pointwise statistical comparisons within each group and between groups were performed using the appropriate paired or unpaired t test. Features were extracted from each load deformation curve for comparative analysis.ResultsThere were no significant differences between the two groups with respect to the patient satisfaction scores or to laxity testing (manual or instrumented). Robotic testing results for within-group comparisons demonstrated a significant reduction in maximum external rotation (8.77°) in the reconstructed leg when compared to the healthy leg (p < 0.05) in the BTB/EAR group, with a non-significant change in internal rotation. The slope of the curve at maximum internal rotation was also significantly greater in the reconstructed legs for the BTB/EAR group (p < 0.05), indicating reduced endpoint compliance or a harder endpoint. Finally, the leg that received the extra-articular tenodesis had a trend towards a reduced total leg axial rotation. Conversely, patients in the BTB group demonstrated no significant differences between their legs. For between-group comparisons, there was a significant increase in maximum internal rotation in the healthy legs in the BTB/EAR group compared with the healthy legs in the BTB group (p < 0.05). If the injured/reconstructed legs were compared, the significant difference at maximum internal rotation disappeared (p < 0.10). Similarly, the healthy legs in patients in the BTB/EAR group had a significantly more compliant or softer endpoint in internal rotation, greater maximum internal rotation, and more internal rotation at torque 0 in their healthy legs compared with the healthy legs in the BTB group (p < 0.05). These same differences were not noted in the reconstructed knees. The only identifiable significant difference between the injured/reconstructed legs was rotation at 0 torque (p < 0.05).ConclusionsIn this group of patients who were at an average of 9 years from surgery, the addition of a lateral extra-articular reconstruction to a standard bone–tendon–bone intraarticular ACL reconstruction does reduces internal rotation of the tibia with respect to the femur when compared to intraarticular reconstruction alone. It appears that the selection process for inclusion into the BTB/EAR group included an increase in total axial rotation of the healthy knee during the examination along with a decrease in endpoint stiffness at maximum internal rotation.Level of evidenceII.

Joint hypermobility syndrome must be investigated in case of snapping scapula syndrome

The snapping scapula syndrome (SSS) is an uncommon clinical picture responsible for significant discomfort. Various diagnoses are known but this problem is often non-specific. The joint hypermobility syndrome (JHS) has never been described in association with SSS. We report three cases of idiopathic SSS associated with JHS. Case 1: Female 18 yo, SSS right, JHS with a Beighton score of 9/9. Maximal passive external rotation of the shoulder > 85°. CT, MRI, Ultrasound and EMG: normal. Treatment with extended rehabilitation. Evolution unchanged. Case 2: Male 32 yo, SSS left, JHS with a Beighton score of 8/9. Maximal passive external rotation of the shoulder > 85°. CT, MRI and EMG: normal. Treatment with rehabilitation. Partially favorable evolution. Case 3: Male 45 yo, SSS right. Previous history of shoulder dislocation with spontaneous reduction. HJS with a Beighton score of 9/9. Maximal passive external rotation of the shoulder > 90°. MRI normal. No further follow-up data. SSS first described by Boinet in 1867 is a rare cause of shoulder pain. A “mechanical conflict” between the rib cage and the scapula is proposed. The conflict may be favoured by the presence of congenital or acquired bone abnormalities (exostosis, scapula fractures), muscle abnormalities (atrophy, tumors) or others like bursitis. In about 30% of the cases SSS no specific cause is found. CT, MRI and EMG are often required in the diagnostic process. Our 3 cases with SSS were only associated with positive criterion of JHS and shoulder passive external rotation more than 85°. Shoulder passive external rotation > 85° is a criteria of shoulder hyperlaxity but not of JHS. Only one patient was known for glenohumeral dislocation. We believe that JHS could be a factor favouring development of non-specific SSS, although the exact mechanism of SSS remains unclear. Treatment is based on rehabilitation often with poor results. We recommend searching a JHS as well as shoulder hyperlaxity in case of SSS.

Kinematics and Kinetics of Youth Baseball Catchers and Pitchers

The purpose of this study was to compare the throwing kinematics and kinetics of youth catchers and pitchers. It was hypothesized that catchers and pitchers would exhibit differences throughout the throwing motion. Descriptive statistics were used to investigate kinematics during the four events of throwing: foot contact (FC), maximum shoulder external rotation (MER), ball release (BR) and maximum shoulder internal rotation (MIR). Additionally, kinetics were investigated within phases of the events: Phase 1 (cocking; FC to MER), Phase 2 (acceleration; MER to BR) and Phase 3 (deceleration; BR to MIR). Results revealed significant difference in torso flexion, lateral flexion, pelvis lateral flexion and segment velocities between the catchers and pitchers. Based on data from the current study, it appears that the youth catchers execute their throw as they have been instructed. It is unclear if the throwing mechanics displayed by these youth are efficient for a catcher, thus further investigation is needed to determine long-term injury susceptibility.

Elasticity of the Coracohumeral Ligament in Patients with Adhesive Capsulitis of the Shoulder.

To evaluate the elasticity of the coracohumeral ligament (CHL) in healthy individuals and patients with clinical findings suggestive of unilaterally involved adhesive capsulitis of the shoulder (ACS). The institutional review board approved this single-institution prospective study, which was performed between November 15, 2012, and July 8, 2014. Informed consent was obtained from all subjects. Measurement of CHL thickness was performed in the axial oblique plane under shoulder maximal external rotation. Shear-wave elastography (SWE) was used to evaluate elasticity of the CHL in healthy individuals (11 men, 19 women aged 22-62 years) and those with clinical findings suggestive of ACS (nine men, 11 women aged 41-70 years). SWE was performed in the shoulder-neutral position and under maximal external rotation. The Wilcoxon signed-rank test was performed to compare the thickness and elastic modulus of the CHL between bilateral shoulders. In all subjects, the CHL elastic modulus was larger under maximal external rotation than in the neutral position (P < .001 for all). For healthy subjects, there was no significant difference in the CHL elastic modulus between the dominant and nondominant shoulders. For patients presumed to have ACS, the CHL thickness was significantly greater in the symptomatic shoulder than in the unaffected shoulder (P < .001). The CHL elastic modulus of the symptomatic shoulder (median, 234.8 kPa; interquartile range [IQR], 174.4-256.7 kPa) was significantly greater than that of the unaffected shoulder (median, 203.3 kPa; IQR, 144.1-242.7 kPa) in the shoulder-neutral position (P = .004) but not under maximal external rotation (P = .123). When bilateral shoulders were maintained at the same angle of external rotation, the CHL elastic modulus was greater in the symptomatic shoulder than in the unaffected shoulder (P = .005). In patients with clinical findings suggestive of ACS, SWE showed that the CHL is stiffer in the symptomatic shoulder than in the unaffected shoulder.

Descriptive analysis of kinematics and kinetics of catchers throwing to second base from their knees

In order to decrease the amount of time that it takes the catcher to throw the ball, a catcher may chose to throw from the knees. Upper extremity kinematics may play a significant role in the kinetics about the elbow observed in catchers throwing from the knees. If relationships between kinematics and kinetics exist then the development of training and coaching instruction may help in reduced upper extremity injury risk. Twenty-two baseball and softball catchers (14.36±3.86years; 165.11±17.54cm; 65.67±20.60kg) volunteered. The catchers exhibited a less trunk rotation (5.6±16.2°), greater elbow flexion (87.9±21.4°) and decreased humeral elevation (71.1±12.3°) at the event of maximum shoulder external rotation as compared to what has previously reported in catchers. These variables are important, as they have previously been established as potential injury risk factors in pitchers, however it is not yet clear the role these variables play in catchers’ risk of injury. A positive relationship between elbow varus torque during the deceleration phase and elbow flexion at MIR was observed (r=0.609; p=0.003). Throwing from the knees reduces a catcher’s ability to utilize the proximal kinetic chain and this may help to explain why their kinematics and kinetics differ from what has previously been presented in the literature.

Hip and upper extremity kinematics in youth baseball pitchers

The purpose of this study was to examine the relationship between dynamic hip rotational range of motion and upper extremity kinematics during baseball pitching. Thirty-one youth baseball pitchers (10.87 ± 0.92 years; 150.03 ± 5.48 cm; 44.83 ± 8.04 kg) participated. A strong correlation was found between stance hip rotation and scapular upward rotation at maximum shoulder external rotation (r = 0.531, P = 0.002) and at ball release (r = 0.536, P = 0.002). No statistically significant correlations were found between dynamic hip rotational range of motion and passive hip range of motion. Hip range of motion deficits can constrain pelvis rotation and limit energy generation in the lower extremities. Shoulder pathomechanics can then develop as greater responsibility is placed on the shoulder to generate the energy lost from the proximal segments, increasing risk of upper extremity injury. Additionally, it appears that passive seated measurements of hip range of motion may not accurately reflect the dynamic range of motion of the hips through the progression of the pitch cycle.

Distension test in passive external rotation: Validation of a new clinical test for the early diagnosis of shoulder adhesive capsulitis

ObjectiveThe aim of this study is to evaluate the internal validity of a clinical test for the early diagnosis of shoulder adhesive capsulitis, called the Distension Test in Passive External Rotation (DTPER). Materials and methodsThe DTPER is performed with the patient standing up, the arm adducted, and the elbow bent at 90°. From this position, a smooth passive external rotation is started, the affected arm being supporting at the wrist with one hand of the examiner and the other maintaining the adducted elbow until the maximum painless point of the rotation is reached. From this point of maximum external rotation with the arm in adduction and with no pain, an abrupt distension movement is made, increasing the external rotation, causing pain in the shoulder if the test is positive. This term was performed on a group of patients with shoulder pain of many origins, in order to analyse the predictive values, sensitivity, specificity, and the likelihood ratio. ResultsThe DTPER showed a sensitivity of 100% (95% CI: 91.8–100%) and a specificity of 90% (95% CI: 82.4–94.8%). The positive predictive value was 0.62 and a likelihood ratio of 10.22 (95% CI: 5.5–19.01). False positives were only found in patients with subscapular tendinopathies or glenohumeral arthrosis. DiscussionThe DTPER has a high sensitivity for the diagnosis of adhesive capsulitis, and is excluded when it is practically negative. False positives can easily be identified if there is external rotation with no limits (subscapular tendinopathy) or with a simple shoulder X-ray (glenohumeral arthrosis).

Computer-assisted external frame for correction of tibial and fibular deformity

Objective To introduce a new computer-assisted external frame for osteotomy to correct complex tibial and fibular deformity. Methods From January 2012 to December 2013, 15 patients with complex tibial and fibular deformity were treated with a computer-assisted external frame and related computer software for surgical correction. All were unilateral limb deformity, involving the left lower limb in 8 cases and the right lower limb in 7 cases. They were 8 males and 7 females, 15 to 43 years of age (average, 26.8 years). The deformity was caused by old osteomyelitis in 9 cases and trauma sequela in 6. The related angles, distances and rotations were measured on the postoperative radiographs of the lower limbs. The data were input into the software to calculate the daily adjustment lengths of the frame rods. Daily frame adjustments were conducted according to the data calculated. The frame was removed when expected results were achieved. The patients lived independently during the adjustment. Results The 15 patients were effectively followed up for 10 to 22 months (average, 15 months). Frame fixation time averaged 8.4 months (from 5.5 to 13.1 months). The reunion time averaged 8.0 months (from 5.4 to 12.1 months). The hospitalization time aver-aged 2.4 months (from 2.0 to 2.8 months). In 10 cases of limb shortening, the shortening lengths averaged 0.5 cm (from 0 to 0.9 cm) after adjustment. In 12 cases of angulation deformity, the angulation averaged 3.3° (from 0° to 5.4°) after adjustment. In 5 cases of rotation deformity, the maximum internal rotation was 5° and the maximum external rotation 10° after correction, deviating from the normal values by 3.5° on av-erage. In 6 cases of horizontal displacement, the displacements averaged 0.5 cm after correction. All patients were satisfactory with corrected lower limb alignment, improved symptoms and appearance, giving a subjective satisfaction rate of 100% . Conclusion Use of computer-assisted external frame in surgical correction of tibial and fibular deformity can achieve satisfactory outcomes in simple, accurate, standardized, minimally invasive manners. Key words: External fixator; Tibia; Fibula; Osteotomy

Association Between Scapular Asymmetry And Shoulder Pain In Juvenile Baseball Players

Objectives:Scapular dyskinesis, defined as an alteration in scapular position and motion, has been suggested as a risk factor for upper extremity injuries. Assessing scapular asymmetry is a simple and easy way to identify scapular dyskinesis that is typically associated with throwing-related injuries. Despite the large number of investigations identifying scapular asymmetry in patients with shoulder pathology, little research has examined the incidence of scapular asymmetry and its association with shoulder injury in young, skeletally immature baseball players. The purpose of this study was to determine the incidence of scapular asymmetry in juvenile baseball players and investigate its association with shoulder injuries.Methods:Two hundred and twenty-three juvenile baseball players aged 9-12 years were included in this study. Each participant submitted a self-completed questionnaire and underwent a physical examination and an imaging assessment of scapular asymmetry. Questionnaire items included the subject's sex, age, position, years of baseball experience, practice frequency and duration, and shoulder pain during throwing over the past 1 year. Tenderness of the proximal humeral epiphysis and pain during maximum external rotation were also assessed on the physical examination. Digital photos of each participant's upper body were taken from behind, first with their arms held straight out to the sides and then with their hands in the air. Scapular asymmetry was evaluated using a computerized image analysis system (Image J version 1.33u; National Institute of Mental Health, Bethesda, MD, USA). Inter- and intra-observer reliability for scapular asymmetry was 0.65 and 0.77, respectively. All analyses were conducted using JMP 10 (SAS Institute, Cary, NC, USA) and p values <0.05 were considered statistically significant.Results:Fifty-three of the 223 subjects had experienced shoulder pain while throwing in the past 1 year. Of these 53 symptomatic subjects, 28 (52.8%) had experienced shoulder pain twice or more in that year, whereas 42 (79.2%) had some kind of throwing disability. The incidence of shoulder pain significantly increased with age and was significantly higher in pitchers than in players of other positions. There was no significant association between shoulder pain and years of baseball experience or amount of practice. Scapular asymmetry was observed 171 (76.7%) subjects. The scapula of the throwing side tended to tilt anteriorly, deviate inferiorly and medially, and rotate downwardly in both the arms at side and hands up positions compared with the scapula on the non-throwing side. Age- and position-adjusted logistic regression analysis revealed that scapular superior deviation and anterior tilting significantly increased the risk of shoulder pain as evidenced by odds ratios (95% confidence interval) of 2.41(1.17-4.98) and 2.36 (1.20-4.67), respectively.Conclusion:Our study demonstrated that approximately three-quarters of juvenile baseball players under the age of 12 years already had scapular asymmetry and that 24% experienced shoulder pain. Scapular superior deviation and anterior tilt, which might be induced by tightness of the pectoralis minor muscle, leads to increased rotational torque at the proximal humeral epiphysis by restricting the scapular posterior tilt during late cocking to the acceleration phase.

How Does the Scapula Move during the Tennis Serve?

This study aimed to describe the scapulothoracic kinematics during the tennis serve in highly skilled tennis players. Thirteen male competitive players performed flat first serves while eight high-speed cameras recorded the three-dimensional trajectories of the 15 markers located on bony landmarks. The scapular position through the tennis serve was determined using the acromial marker cluster method. The results revealed that, during the cocking phase, the scapula externally rotated and posteriorly tilted to attain the maximal humeral external rotation. During the acceleration phase, the scapula upwardly rotated and anteriorly tilted to reach maximal racket head height. During the follow-through phase, the scapula internally and downwardly rotated, and posteriorly tilted, while the upper limb lowered and crossed the player's body. The findings of this study provide new knowledge on the asymptomatic scapular motion during the tennis serve, which may help clinicians and coaches to understand the overhead sport motion mechanics and to better prevent and rehabilitate overhead shoulder injuries.

Effect of Anterior Capsular Laxity on Horizontal Abduction and Forceful Internal Impingement in a Cadaveric Model of the Throwing Shoulder

Background: Excessive anterior capsular laxity (elongation of the anterior capsular ligaments) causes shoulder subluxation during acceleration of the throwing motion, leading to a disabled throwing shoulder. Few biomechanical studies have investigated the relationship between anterior capsular laxity and internal impingement, another cause of the disabled throwing shoulder. Purpose/Hypothesis: The purpose of this study was to assess the effect of anterior capsular laxity on forceful internal impingement during the late cocking phase. The hypothesis was that excessive anterior shoulder laxity caused by elongation of the anterior capsular ligaments will increase the horizontal abduction angle to increase glenohumeral contact pressure. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric shoulders were tested with the shoulder abducted to 90° and at maximal external rotation to simulate the late cocking phase of the throwing motion. The angle of external rotation, anterior translation, angle of horizontal abduction, locations of the articular insertion of the rotator cuff tendons (supraspinatus and infraspinatus) on the greater tuberosity relative to the glenoid, and the glenohumeral contact pressure and area during internal impingement were measured. All data were compared between intact and elongated anterior capsule, which was created by repeatedly applying external rotational stretching. Results: Elongation of the anterior capsular ligaments was confirmed by the increase in glenohumeral external rotation and anterior translation after our stretching technique. Location data showed that the posterior half of supraspinatus tendon, the entire infraspinatus tendon, and the posterosuperior labrum were impinged between the greater tuberosity and glenoid. Maximal glenohumeral horizontal abduction (2.2% increase; P = .003) and glenohumeral contact pressure (27.3% increase; P = .04) were significantly increased in the shoulder joint with increased anterior capsular laxity as compared with the intact condition. Conclusion: Increased anterior capsular laxity created by applying repetitive excessive external rotational torque significantly increased horizontal abduction and contact pressure in the glenohumeral joint. Concurrently, the supraspinatus and infraspinatus tendons and posterosuperior labrum were impinged between the greater tuberosity and glenoid. Clinical Relevance: Increased anterior capsular laxity may exacerbate forceful internal impingement during the late cocking phase of the throwing motion.

The Effects of Ankle Bracing and Direction on Knee Angles During Single-Leg Hop Tasks

Bracing is commonly used for support and stabilization of the ankle during physical activity. As bracing is intended to minimize ankle movement, transient effects at the knee are not always considered and may increase injury risk due to improper joint mechanics. PURPOSE:To assess the effects of ankle bracing techniques (ABT) on knee angles during the landing phase of single-leg hop (SLH) tasks. METHODS:15 subjects were recruited (21.9±1.7 years, 1.78±.27m, 70.0±17.1kg) and were free from any previous traumatic lower body injuries. Reflective markers were applied to the participants’ lower extremities and trunk, and tasks were captured using a 3-D motion analysis system. For each participant, an initial control session was performed in a non-braced condition for the SLH tasks. For the subsequent three sessions, an ABT was applied (white tape, lace-up brace, and kinesio-tape). The type of ABT used during each session was counterbalanced between participants. Each session, participants performed a SLH task from five different starting positions, all within 70 cm from the target landing zone. Peak knee angles (°) were measured for all joint rotations during the landing phase. A multivariate analysis of variation (MANOVA) was performed to examine the main and interaction effects of ABT and SLH direction. An alpha level was set at .05 a priori, with Tukey’s HSD performed post hoc to discern differences if significance was found. RESULTS: MANOVA results exhibited no significant differences for the main effect of ABT (p>.05), but significant differences were demonstrated for the main effect of SLH direction (p=.001). Minimal knee flexion demonstrated significant differences for the lateral (-22.5±6.4°) compared to anterior (-18.7±4.9 °;p=.004), anteromedial (-18.9±5.6°;p=.006) and medial (-19.5±6.5°;p=.004) directions of the SLH. Maximal external knee rotation displayed significant differences for the lateral (-0.2±5.3°) compared to the medial (-3.0±6.1°;p=.035) SLH direction. CONCLUSIONS: The results indicate that ankle bracing does not significantly alter joint mechanics at the knee, whereas SLH direction does have an effect on knee angles during the landing-phase. When considering the prevention and probability of knee injuries, attention to the direction of the movement performed is an important factor.

Relationship between shoulder abduction angle and shoulder joint complex angle at shoulder maximum external rotation during throwing motion

Relationship between shoulder abduction angle and shoulder joint complex angle at shoulder maximum external rotation during throwing motion

Effects of Mobilization With Movement on Pain and Range of Motion in Patients With Unilateral Shoulder Impingement Syndrome: A Randomized Controlled Trial

ObjectiveThe purpose of this study was to compare the immediate effects of mobilization with movement (MWM) to a sham technique in patients with shoulder impingement syndrome. MethodsA randomized controlled trial was performed. Forty-two patients (mean ± SD age, 55 ± 9 years; 81% female) satisfied eligibility criteria, agreed to participate, and were randomized into an MWM group (n = 21) or sham manual contact (n = 21). The primary outcome measures including pain intensity, pain during active range of motion, and maximal active range of motion were assessed by a clinician blinded to group allocation. Outcomes were captured at baseline and after 2 weeks of MWM treatment or sham intervention. The primary analysis was the group×time interaction. ResultsThe 2×2 analysis of variance revealed a significant group×time interaction for pain intensity during shoulder flexion (F = 7.054; P = .011), pain-free shoulder flexion (F = 32.853; P < .001), maximum shoulder flexion (F = 18.791; P < .01), and shoulder external rotation (F = 7.950; P < .01) in favor of the MWM group. No other significant differences were found. ConclusionsPatients with shoulder impingement syndrome who received 4 sessions of MWM exhibited significantly better outcomes for pain during shoulder flexion, pain-free range of shoulder flexion, maximal shoulder flexion, and maximal external rotation than those patients who were in the sham group.

An inferential investigation into how stride length influences temporal parameters within the baseball pitching delivery

Motion analyses of lower body mechanics offer new schemas to address injury prevention strategies among baseball pitchers, where the influence of stride length remains unknown. This study examined the temporal effect of stride length at constituent pitching events and phases. Nineteen competitive pitchers (15 collegiate, 4 high school) were randomly assigned to pitch two simulated, 80-pitch games at ±25% of their desired stride length. An integrated, three-dimensional motion capture system recorded each pitch. Paired t-tests were used to determine whether differences between stride conditions at respective events and within phases were significantly different. The results demonstrate the shorter strides mediated earlier onset of stride foot contact, reduced time in single support whereas double support intervals increased (p<.001). The opposite was observed with the longer strides. However, the acceleration phase, which comprises the highest throwing arm kinematics and kinetics, remained unchanged. The interaction between stride length, stride foot contact onsets, and time in single support is inferentially evidenced. The equivalent acceleration phases suggest stride length alone influenced time in single and double support by altering the onset of stride foot contact, which perhaps affects the mechanics in preparing the throwing arm for maximal external shoulder rotation.

Lower body predictors of glenohumeral compressive force in high school baseball pitchers.

The purpose of this study was to better understand how lower body kinematics relate to peak glenohumeral compressive force and develop a regression model accounting for variability in peak glenohumeral compressive force. Data were collected for 34 pitchers. Average peak glenohumeral compressive force was 1.72% ± 33% body weight (1334.9 N ± 257.5). Correlation coefficients revealed 5 kinematic variables correlated to peak glenohumeral compressive force (P < .01, α = .025). Regression models indicated 78.5% of the variance in peak glenohumeral compressive force (R2 = .785, P < .01) was explained by stride length, lateral pelvis flexion at maximum external rotation, and axial pelvis rotation velocity at release. These results indicate peak glenohumeral compressive force increases with a combination of decreased stride length, increased pelvic tilt at maximum external rotation toward the throwing arm side, and increased pelvis axial rotation velocity at release. Thus, it may be possible to decrease peak glenohumeral compressive force by optimizing the movements of the lower body while pitching. Focus should be on both training and conditioning the lower extremity in an effort to increase stride length, increase pelvis tilt toward the glove hand side at maximum external rotation, and decrease pelvis axial rotation at release.

The changes in shoulder rotation strength ratio for various shoulder positions and speeds in the scapular plane between baseball players and non-players.

[Purpose] This study aimed to investigate the effect of shoulder positions and speeds on internal and external rotation torque of college baseball players and age-matched non-players. [Subjects] Twenty first-level collegiate baseball players and 19 college students were recruited. [Methods] A dynamometer system was used to evaluate the shoulder rotation strength in sitting postures. Three testing positions, namely shoulder abduction of 45°, 70°, and 90° in the scapular plane, were combined with three testing speeds at 60°/s, 120°/s, and 210°/s. [Results] The maximum external and internal rotation torques both occurred at shoulder abduction of 70°. However, only external rotation torque was affected by the speed, with the peak value observed at 60°/s. The internal rotation torque of baseball players was larger than that of the control group under all testing conditions, but the external rotation did not show any difference. The ratio of external to internal rotation torque changed with the testing positions and speeds in both groups. The ratio in the control group was greater than that in the player group. [Conclusion] The shoulder position could affect the rotational strength, and the baseball players could strengthen their external rotators for better performance and injury prevention.

Detection and prevention of glenohumeral epiphysiolysis.

Proximal humeral epiphysiolysis (a.k.a. Little League shoulder) is most commonly seen in adolescent throwing athletes from ages 11 to 16 years (1,4). The pathology is a widening of the physis, resulting in a Salter-Harris I fracture (see Figure) (8). Biomechanically, due to weaker developing epiphyseal plates, torque during maximum external shoulder rotation and excessive laxity may predispose the young thrower to this type of injury (9,10).Figure: Notice the widening of the right proximal humeral physis (on the left) compared with that in the left in this 13-year-old pitcher.Important information to elicit includes whether the athlete is a pitcher or catcher, the number and type of pitches thrown per game and season, the frequency of pitching, and the number of leagues in which the athlete competes. The quality, severity, and specific location of pain experienced as well as when the pain occurs during pitching motion are important information to obtain (4). Patients typically present with pain occurring in the shoulder that has progressively worsened over several months while throwing hard (1). The most consistent physical examination finding is tenderness over the proximal humeral physis (1). While anterior-posterior radiographs in internal and external rotation with widening of the proximal humeral physis is the hallmark of Little League shoulder, there also may be fragmentation of the lateral metaphysis, sclerosis, cystic changes, and demineralization of the proximal humeral metaphysis (2). Additionally, widening of the physis does not necessarily correlate to symptoms. An important pearl is to always obtain comparison radiographs of the nonthrowing shoulder. Magnetic resonance imaging (MRI) studies also have been used for further imaging detail with success (2). However, MRI is typically not indicated unless there is suspicion of additional injury and/or no improvement with rest for at least 3 wk (3). Nonoperative treatment typically begins with 6 wk of complete rest. If the patient is asymptomatic at rest, nonthrowing physical therapy may begin at week 7. At 3 months, if asymptomatic, a progressive throwing program with subsequent return to play is standard. Overuse throwing injury can be minimized by following national recommendation guidelines, which major league baseball has now endorsed, on pitch counts, rest days, pitch type based on age, use of radar guns, and yearly arm rest recommendations (4–7,11).

C-20 野球投球時の指力と上肢キネマティクスの関連(投げ)

The purpose of this study was to investigate a relationship between finger force and upper limb kinematics for baseball pitching. Two collage baseball pitchers participated in the experiment and threw a four-seam fastball 10 times. A force transducer was installed in a baseball to make a direct measurement of force imparting on the ball by index finger during pitching (2000 Hz). A pitching motion was captured using 12 infrared cameras (500 Hz). The finger force showed a bimodal pattern for both participant. The 1st peak appeared at a moment of maximum shoulder external rotation (45-50 ms before instant of ball release). The 2nd peak appeared at 7-8 ms before instant of ball release. It was considered that the 2nd peak reflected angular velocity of shoulder internal rotaion.

Hip range of motion and scapula position in youth baseball pitching pre and post simulated game

Lower to upper extremity sequencing of energy and force is linked by virtue of the scapula. It was the purpose of this study to examine the relationship between passive hip rotational range of motion and scapular kinematics during baseball pitching. Nineteen youth baseball players (11.3 ± 0.6 years; 151.8 ± 8.8 cm; 45.9 ± 10.9 kg) with no history of injury participated. Bilateral hip passive rotational range of motion was measured pre and post pitching a simulated game. Scapular kinematics at the position of shoulder maximum external rotation during the pitching cycle were recorded in the first and last innings of the simulated game. Post simulated game, stance leg hip passive internal rotation revealed significant correlations (r = −0.57, P = 0.01) with scapula anterior/posterior tilt at the pitching event of maximum humeral external rotation. The current study reveals that pitching a simulated game results in alterations throughout the kinetic chain. Specifically, this study strengthens the notion that lumbopelvic-hip complex parameters play a significant role in shoulder motion. With this link identified, it is suggested that clinical focus be directed musculature about the lumbopelvic-hip complex as well as muscles that work to stabilise the scapula during dynamic movement.