Nonthrowing Side Research Articles

Association Between Acromiohumeral Distance, Shoulder Rotational Strength, And Range of Movements in University Basketball Players: A Cross-Sectional Study

Objective: Limited information exists regarding the sports-related adaptations at the shoulder complex in university basketball players. Therefore, this study aimed to evaluate the shoulder rotational muscle strength, range of movements (ROM), and acromiohumeral distance (AHD) values to interpret side-to-side differences regarding injury risk factors in throwing and non-throwing shoulders of university basketball players. Materials and Methods: Twenty university basketball players (10 males, 10 females; age=20.2±1.8 years; body mass index=21.1±2.22 kg/m2) were included. AHD values, isometric and concentric strengths of shoulder external (ER) and internal rotation (IR), and shoulder ER, IR, and total rotational ROM were measured bilaterally. Results: AHD was greater on the throwing side at 0° (p<0.001) and 60° of shoulder abduction positions (p<0.001). However, throwing shoulders demonstrated more AHD reduction from 0° to 60° of shoulder abduction (p=0.01). We found greater isometric ER strength (p=0.006), ER/IR ratio (p=0.001), concentric ER strength (p<0.001), concentric ER/IR ratio (p<0.001), and ER ROM (p<0.001) in the throwing shoulders. Besides, AHD was correlated with isometric ER strength on the throwing side (p=0.012, r=0.552) and non-throwing side (p=0.041, r=0.461), also, isometric ER/IR strength ratio on the throwing side (p=0.017, r=0.526) and the non-throwing side (p=0.013, r=0.545). Conclusion: University basketball players demonstrated stronger ER muscle strength, higher ER/IR strength, increased ER ROM, and wider AHD values on the throwing shoulders. Moreover, greater ER muscle strength and ER/IR strength ratio were associated with greater AHD.

Prevalence of impaired foot function in baseball players with and without disabled throwing shoulder/elbow: a case–control study

Prevalence of impaired foot function among baseball players with and without a disabled throwing shoulder/elbow was investigated. The study included 138 male players. Players who had previously complained of shoulder/elbow pain during throwing motion were defined as the players with a history, and those who experienced shoulder/elbow pain during the examination were defined as having the injury. Foot function was evaluated by foot “rock paper scissors” movements and floating toes. Their prevalence was assessed and the relationships between players with and without the injuries were statistically analyzed. The prevalence of players with a history and injury was 27% and 7%, respectively. The prevalence of impaired foot function on the non-throwing side among players with injury was significantly higher than those without (60% vs. 28%, P < 0.001) and higher tendency on the throwing side than those without (60% vs. 32%). Regarding floating toes, players with a relevant history showed a significantly higher prevalence on the throwing side than those without (49% vs 28%, P < 0.001) and higher tendency on the non-throwing side than those without (49% vs 32%). Players with disabled throwing shoulder/elbow have a significantly higher prevalence of impaired foot function and floating toes than players without it.

Characteristics of Lumbar Spondylolysis in Adolescent Baseball Players: Relationship between the Laterality of Lumbar Spondylolysis and the Throwing or Batting Side.

A retrospective, cross-sectional study was conducted to analyze the implications of asymmetric baseball movements on the incidence of spondylolysis. This study aimed to evaluate the relationship between asymmetric movements and the laterality of spondylolysis. Baseball, characterized by its asymmetric throwing and batting, may disproportionately stress one side. Lumbar spondylolysis is a frequent cause of lower back pain in young athletes, particularly those involved in activities with consistent unilateral rotations such as baseball. However, whether a link exists between the laterality in spondylolysis and the dominant throwing/ batting side or whether disparities exist between pitchers and fielders remains unclear. The study included 85 players. Participants were divided into two groups: pitchers and fielders. The association between the laterality of spondylolysis and the throwing/batting side in the overall cohort and between the two groups was evaluated. Among pitchers, 16 lesions appeared on the throwing side and 32 on the nonthrowing side (p =0.029). For fielders, no notable difference was observed between the two sides (p =0.363). Furthermore, batting preference did not influence the laterality of spondylolysis in either group. Adolescent baseball players, particularly pitchers, exhibited a higher incidence of lumbar spondylolysis on the side opposite their throwing arm. The findings of this study highlight the significant effect of asymmetrical sporting activities on the development of spondylolysis, to which pitchers are particularly susceptible.

Optimal Limb Position for the Stress Ultrasound Evaluation of Elbow Valgus Laxity in Baseball Players.

The optimal limb position during stress ultrasound (SUS) evaluation of elbow valgus laxity has not been standardized. To compare 2 elbow positions (at 90° and 30° of flexion) and report which position method better represents the increased valgus laxity characteristics of baseball players. Controlled laboratory study. Eighteen college baseball players with no history of elbow pain or elbow disorders who belonged to a college baseball club between April and November 2021 participated in this study. The medial elbow joint space (MEJS) was recorded by ultrasonography at rest and under valgus stress, and the difference in MEJS between the conditions was considered the valgus laxity. For all participants, the MEJS was recorded at 90° and 30° of elbow flexion. In the 90° of flexion position, the participant was positioned in the supine position with abduction and external rotation of the shoulder, and 2.5 kgf of valgus stress was applied proximally to the wrist. In the 30° of flexion position, the participant was positioned in the sitting position with abduction and external rotation of the shoulder, and 3.0 kgf of valgus stress was applied to the ulnar head. Valgus laxity on the throwing and nonthrowing sides was compared between the 2 elbow positions using paired t tests or Wilcoxon signed-rank tests after checking the normality. There was a significant difference in valgus laxity on the throwing side between the 90° and 30° of flexion positions (1.9 vs 1.1 mm, respectively; P = .002), whereas no significant difference between positions was seen on the nonthrowing side (P = .06). SUS with the elbow flexed at 90° more clearly detected valgus laxity in the study participants than the 30° of flexion position. The quantitative evaluation of valgus laxity is important for baseball players to assess the risk of ulnar collateral ligament injury.

Investigation of the limiting factors of shoulder joint complex motion in college baseball players: motion analysis of the humeral head and rotator cuff using ultrasound

BackgroundThe relationship between lower mobility, as measured by the elbow forward translation motion (T-motion) test, a new indicator of shoulder joint complex movement that measures elbow position when both dorsal hands are placed on the iliac crest while in a sitting position, and the parameters calculated by ultrasonography is unknown. The purpose of this study was to investigate the limiting factors of T-motion through motion analysis of the humeral head and rotator cuff muscles using ultrasonography in college baseball players. MethodsThirteen college baseball players participated in this cross-sectional study. The shortest distance from the posterior edge of the glenoid to the humeral head was measured in the static and T-motion positions, and the difference was calculated as the humeral head translation. The velocity of the infraspinatus was calculated during shoulder internal/external rotation using the particle image velocimetry method. These parameters were compared between the throwing and nonthrowing sides to examine the limiting factors of T-motion. ResultsThis study indicated moderate-to-good reliability for the parameters calculated by ultrasonography. The mean anterior translation distance was significantly greater on the throwing side than on the nonthrowing side (r=0.56, p=.015). The mean velocity of infraspinatus during internal rotation was significantly lower on the throwing side than on the nonthrowing side (r=0.51, p=.028). ConclusionIncreased anterior translation of the humeral head and decreased the velocity of infraspinatus are likely correlated with reduced T-motion mobility in college baseball players. These methods showed potential for physical therapy assessment and intervention to prevent shoulder dysfunction.

Relationship Between Lumbar Locked Rotation, Trunk Rotation During Pitching, and Pitch Velocity in High School Baseball Players.

Trunk rotation during pitching correlates with pitching velocity and load on the joints of the upper limb. Trunk rotation is often focusing on during teaching the pitching motion. Athletes who exhibit early trunk rotation during pitching often have low thoracic spine rotational range of motion. The purpose of this study was to investigate the relationship between the range of thoracic spine rotation measured using the lumbar locked rotation test (LLR-t), hip-shoulder separation (H/S) and thoracic rotation angle at stride foot contact (SFC), and ball velocity. Descriptive laboratory study. Fifteen healthy male high school students belonging to a baseball club were recruited for participation. The throwing side and non-throwing side LLR-t was performed using an inclinometer. Hip-shoulder separation and thoracic rotation angle during SFC were measured using a pitching motion analysis application: Pitch AI. In addition, a tracking device specifically designed for pitching：Pitching2.0 was employed to measure ball velocity. Correlations between LLR angle, H/S, trunk rotation angles at SFC, and ball velocity were examined using Pearson's correlation coefficient. There was a positive correlation（r=0.52，p=0.047） between the LLRt angle and H/S. Additionally, there was a negative correlation（r=-0.62, p =0.01） between the LLRt angle on the throwing side and thoracic rotation angle. There was a positive correlation(r=0.54, p=0.04) between ball velocity and H/S and a negative correlation(r=-0.56, p=0.03) between ball velocity and thoracic rotation angle during SFC. . The LLR-t measures thoracic rotation angle with the pelvis-lumbar spine fixed. The results indicated that throwing side LLR was related to the thoracic angle during SFC and hip-shoulder separation. 3.

Relationship between shoulder rotation deficit and elbow instability in healthy baseball players.

Elbow valgus instability is a risk factor for elbow medial collateral ligament injury. This study aimed to investigate the relationship between shoulder range of motion and elbow valgus instability using an ultrasound imaging system. A questionnaire and ultrasound examination were used for the study. Thirty-seven high school baseball players (15-18 years) with no history of shoulder or elbow disorders were included. Shoulder range of motion was measured at 90° of adduction, 10° of horizontal adduction, and 90° of elbow flexion in the supine resting position. To evaluate elbow valgus instability, an ultrasound imaging system was used to measure the shortest distance from the apex of the ulnar capitulum to the humeral glenoid with 2.5 kg of valgus stress applied to the ulnohumeral joint. The presence of elbow valgus instability was determined by the value obtained by subtracting the joint space distance on the non-throwing side from that on the throwing side. Student's t-test was applied for the range of shoulder rotation between the two groups, and Pearson's correlation coefficient was used for the relationship between the range of shoulder rotation and elbow instability. Statistical significance was set at 5%. The range of internal and total shoulder rotation was significantly lower in participants with elbow valgus instability than those without elbow valgus instability (P<0.001). In addition, a significant moderate correlation was found in the range of internal (r=0.608, P<0.001) and total shoulder (r=0.479, P<0.001) rotations. Decreased shoulder range of motion may affect elbow valgus instability.

Bilateral Humeral Retrotorsion Angle Measured Using an Ultrasound-Assisted Technique in Asian Baseball Players.

Repetitive pitching is thought to restrict the physiological derotation process of the humeral head. Some studies have reported that side-to-side differences in the humeral retrotorsion angle (ΔHRA) occur between the ages of 9 and 11 years in baseball players. However, it remains unclear whether the ΔHRA in Asian baseball players depends on pitching skill or competitive level. To evaluate the ΔHRA in Asian collegiate and professional baseball players and to determine the effects of pitching activity on the physiological derotation process of the humeral head. Cross-sectional study; Level of evidence, 3. We evaluated 128 shoulders in 64 Asian baseball players who were stratified into 4 groups as follows: 13 professional pitchers; 9 professional fielders; 8 collegiate pitchers; and 34 collegiate fielders. The throwing and nonthrowing side HRA was assessed using an ultrasound-assisted technique, and the ΔHRA was compared among the 4 groups. In addition, Pearson correlation analysis was used to assess the relationship between ΔHRA and glenohumeral range of motion, baseball starting age, and fastball velocity in pitchers. The HRA was significantly greater in the throwing arm than in the nonthrowing arm in each group, with no significant differences among the groups. There was no correlation between ΔHRA and range of motion or fastball velocity. There was a significant negative correlation between baseball starting age and ΔHRA in professional fielders (r = -0.633; P = .036). The findings of the present study provide evidence that in Asian baseball players, the HRA was significantly greater in the throwing arm than in the nonthrowing arm. There were no clear associations between HRA and pitching ability or competitive level.

Are floating toes associated with lifestyle in children? A cross-sectional study

BackgroundFloating toes are a condition and deformity in which some of the toes are afloat. Many functional impairments in floating toes have been previously studied lately and several factors related to floating toes have also been reported. However, no reports have considered the relationship between lifestyle and floating toes among children. The purpose of this study was to reveal the prevalence of floating toes among school children and reveal its relationship with lifestyle.MethodsIn total, 138 young male baseball players were recruited. Lifestyle was evaluated by using a questionnaire and chosen whether the main lifestyle was Japanese or Western, if the bedding was futons or beds, and if the toilet was Japanese style (a squat toilet) or Western style. Floating toes were defined as toes that were not in contact with the mat. Ankle dorsiflexion in the knee-flexed and knee-extended positions was measured in a weight-bearing position. The relationship between the floating toes and lifestyles, and the comparison of ankle dorsiflexion range of motion between the lifestyles were statistically analyzed.ResultsPlayers living in a Western style showed a significantly higher prevalence of floating toes on both feet compared with the players living in a Japanese style (throwing side; 39% vs. 19%, p = 0.04, and non-throwing side; 43% vs. 19%, p = 0.01). Players living in a Western style with beds showed a significantly smaller range of motion on both sides of ankle dorsiflexion in the knee-flexed position compared with those who were not (throwing side; 37.2 ± 5.7° vs. 39.0 ± 6.6°, p = 0.04, and non-throwing side; 36.8 ± 5.8° vs. 38.6 ± 6.1°, p = 0.04).ConclusionChildren mainly living in a Western lifestyle showed a significantly higher prevalence of floating toes on both feet compared to those mainly living in a Japanese lifestyle. The prevalence of floating toes may be related to lifestyles among children.Trial registrationThe study was approved by the institutional review board of the Waseda University Graduate School of Sport Sciences (IRB number 2021–185).

Evaluation of flexor digitorum superficialis function in adolescent baseball players.

Increased flexor digitorum superficialis (FDS) tendon activity can be a therapeutic target for elbow disorders in adolescent baseball players. The proportion of adolescent baseball players who can use FDS independently is unknown, and which finger is most often used remains unclear. This study investigated whether adolescent baseball players intentionally used FDS on each finger. Adolescent baseball players were recruited and assessed for FDS function for each finger using the standard technique. Sixty-nine participants (mean age: 10.4 years) were recruited. Participants numbered 33, 56, 59, and 25 on the throwing side and those numbered 28, 46, 54, and 33 on the nonthrowing side could independently flex the proximal interphalangeal joint while holding their palms in the index, middle, ring, and small fingers, respectively. When assessing both throwing and nonthrowing participants, a significant number of participants could independently flex the proximal interphalangeals of the ring and middle fingers but had difficulty with the index and small fingers (P<.001). No significant difference was noted between the throwing and nonthrowing participants in any finger (P>.05). One study reported that participating baseball players with elbow pain have more medial elbow joint space than those without pain symptoms. In another study on finger movements during pitching motion, the force of the thumb, index, middle, and ring fingers was greatest immediately before maximum external rotation. According to both reports, FDS function, especially in the index finger, can be a therapeutic target for medial-sided elbow injuries in adolescent baseball players.

Elasticity of the Scalene Muscles in Collegiate Baseball Pitchers Using Shear Wave Elastography.

Background:Thoracic outlet syndrome is more common in overhead athletes. The anterior and middle scalene muscles have been associated with thoracic outlet syndrome; however, the relationship between the elastic moduli of the scalene muscles and the overhead-throwing position has not been evaluated.Purpose:To investigate the elastic moduli of the anterior and middle scalene muscles in simulated throwing positions using shear wave elastography.Study Design:Descriptive laboratory study.Methods:We enrolled collegiate baseball players who underwent preseason medical checkups in January and February 2020. The anterior and middle scalene muscles were visualized in the short-axis view using ultrasound. In this view, the elastic moduli of the anterior and middle scalene muscles were measured using shear wave elastography in the following arm and neck positions: (1) adduction and neutral rotation of the shoulder (neutral), (2) 90° of abduction and external rotation of the shoulder (ABER), and (3) ABER with neck rotation toward the nonthrowing side (ABER+NR). Repeated-measures analysis of variance and a paired t test were used to compare the elastic modulus values among the 3 positions and between the 2 muscles, respectively.Results:Overall, 30 baseball players were included. In both scalene muscles, the elastic moduli were significantly greater in the ABER versus neutral position (anterior scalene: 14.4 ± 3.8 vs 9.4 ± 2.0 kPa, respectively [P < .001]; middle scalene: 15.8 ± 5.0 vs 10.9 ± 3.4 kPa, respectively [P < .001]). In the neutral position, the elastic modulus was significantly greater in the middle scalene than the anterior scalene (10.9 ± 3.4 vs 9.4 ± 2.0 kPa, respectively; P = .03). In the ABER+NR position, the elastic modulus was significantly greater in the anterior scalene than the middle scalene (18.1 ± 4.6 vs 15.8 ± 2.6 kPa, respectively; P = .03).Conclusion:Because the ABER position was a simulation of the throwing position, these results indicate that this position could be associated with high elastic moduli of the scalene muscles, and both the anterior and middle scalene muscles may be involved.

Ultrasonographic appearance of the pronator quadratus muscle in high school baseball pitchers with and without elbow symptoms: a pilot study.

Earlier reports have described forearm flexor muscles as active stabilizers of the elbow to valgus stress during throwing motion. The pronator quadratus (PQ) muscle acts in coordination with the pronator teres muscle for forearm pronation. This study of high school pitchers was conducted to assess the association between sonographic appearance and a history of elbow symptoms. We examined 123 high school baseball pitchers, all of whom had completed a self-administered questionnaire, including items related to throwing-related elbow joint pain sustained during the prior year. Ultrasound examination was made of the pitchers with and without valgus stress of the medial aspect of the bilateral elbows. The sonographic appearance of the PQ was assessed on sagittal and axial images on the bilateral side. For participants with and without a history of elbow symptoms, we compared the maximum thickness of the PQ on sagittal and axial images of the throwing side. Regarding maximum thickness of the PQ on the sagittal and axial images, a significant difference was found between the throwing and non-throwing sides (throwing side vs non-throwing side mean: sagittal 6.3mm vs 5.7mm, axial 8.2mm vs 7.5mm, 95% confidence interval: sagittal 0.41-0.70, p < 0.001, axial 0.53-0.82, p < 0.001). The maximum thickness of the PQ on axial images with elbow symptoms was significantly greater than the PQ thickness of those without elbow symptoms. Nevertheless, no association was found between elbow valgus instability and the maximum thickness of the PQ on sagittal and axial images of the throwing side. Sonographic appearance of the PQ might be associated with elbow joint conditions in high school baseball players.

Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball Seasons?

BackgroundA pattern of scapular dyskinesis on the dominant side has been demonstrated to be associated with a decrease in throwing arm conditions identified by a self-report outcome assessment in collegiate baseball pitchers during the course of a single season. However, it is unclear if symptomatic shoulders in baseball pitchers may be associated with the presence of scapular dyskinesis.PurposeTo study the relationship between the presence of scapular dyskinesis and throwing-related injury in collegiate baseball pitchers during each respective course of up to four subsequent seasons.MethodsA single Division 1 National Collegiate Athletic Association team participated in this study over a four-year-period. The scapular dyskinesis test was implemented during the preseason for baseball pitchers. Players were followed throughout each respective season to track the incidence of throwing-related upper extremity injuries.ResultsA total of 36 collegiate baseball pitchers (height: 185.3 ± 5.6 cm, weight: 88.8 ± 7.8 kg, age: 20.0 ± 1.5 years) consisting of 57 pitcher seasons were followed in this study, in which 18 pitchers remained with the team for more than one year. Twenty-seven of the 57 pitchers were classified as having scapular dyskinesis demonstrated at around 90° of shoulder flexion on the throwing side. Five injuries (13.2% of a total of 38 injuries) were diagnosed as throwing-related shoulder injuries during the course of the intercollegiate baseball seasons. Four of the five throwing-related shoulder injuries occurred in pitchers who had scapular dyskinesis on their dominant side. Consequently, the odds ratio was 5.04 for the collegiate pitchers with scapular dyskinesis on the throwing arm side associated with a throwing-related shoulder injury compared to those with no scapular dyskinesis (p = 0.16). No relationship was identified between scapular dyskinesis on the throwing arm side and throwing-related elbow injury. Eighty-one percent of the scapular dyskinesis test results were not changed on the throwing side from the previous to the following year for those 18 pitchers who were followed for more than one season, whereas 42.9% of the results remained unchanged on the non-throwing side.ConclusionThe results suggest that collegiate baseball pitchers with dominant arm scapular dyskinesis likely are at increased risk of throwing-related shoulder injury.Level of evidenceLevel 2, Prospective Cohort Study

Posterior shoulder stiffness was associated with shoulder pain during throwing in college baseball players: assessment of shear wave elastography.

To investigate shoulder stiffness on the throwing and non-throwing sides in college baseball players using ultrasound shear wave elastography (SWE), and investigate the relationship between stiffness and shoulder pain during throwing. Forty-nine college baseball players (98 shoulders) were recruited. Shoulder range of motion was evaluated. SWE was used to measure stiffness of the bilateral supraspinatus tendons, infraspinatus tendons, subscapularis tendons, supraspinatus muscles, infraspinatus muscles (ISPM), and posterior capsules. Participants were divided into pain and no pain groups based on the presence or absence of shoulder pain during throwing within 1month before measurements on the throwing side. Items were compared between the throwing and non-throwing sides, and between the pain and no pain groups. Factors affecting shoulder pain during throwing were also investigated via multiple logistic regression analysis. Compared with the non-throwing side, the throwing side had significantly greater external rotation at 90° abduction, significantly lesser internal rotation at 0° abduction and internal rotation at 90° abduction (AbdIR), significantly higher SWE values of the infraspinatus tendon, ISPM, and posterior capsule, and significantly lower SWE values of the subscapularis tendon. Compared with the no pain group, the pain group had a significantly higher SWE value of the ISPM, and significantly lesser AbdIR. Increased ISPM SWE values and decreased AbdIR were significantly correlated with shoulder pain during throwing. The posterior tissue was stiffer than the anterior tissue on the throwing side. Decreased AbdIR and increased ISPM stiffness may be correlated with shoulder pain during throwing.

Hypermobility of ulnar nerve does not affect throwing performance (122)

Objectives:Ulnar nerve neuropathy around the elbow is a common pathology in throwing athletes, and occurs due to many factors including valgus elbow, and ulnar nerve hypermobility. For patients with ulnar nerve neuropathy, anterior transposition of the ulnar nerve is common procedures. Meanwhile, Ulnar nerve hypermobility has been reported to be present in 2% to 47% of asymptomatic individuals. However, no studies have investigated the rate of ulnar nerve hypermobility in throwing athletes, and the relationship between ulnar nerve mobility, and clinical symptom and throwing performance. This study was designed to classify the sonographic assessment for the mobility of the ulnar nerve compared to physical evaluation, and to determine whether ulnar nerve hypermobility is associated with clinical symptoms and throwing performance in baseball players. We investigated ulnar nerve hypermobility using ultrasound to evaluate the relationship between the ulnar nerve hypermobility and clinical sign including throwing performance in college baseball players.Methods:138 elbows in 69 college baseball players were examined. Each participant was queried regarding symptoms attributable to the ulnar nerve. In addition, structural measurements consisting of the tinel test and elbow flexion compression testing were examined. Sonographic examiners were, unaware of reported symptoms, independently performed a standardized examination of both elbows to assess ulnar nerve hypermobility. For sonographic assessment, the ultrasound probe was located at the medial condyle of the humerus to visualize the ulnar nerve in short-axis view in the extended elbow position. During extension to flexion of the elbow, the mobility of ulnar nerves was assessed, and categorized as stable, or hypermobile, which was further subclassified as subluxation, or dislocation (Figure 1A, 1B, 1C). Pared t-test was used to compare the mobility of the ulnar nerve between throwing and non-throwing sides. Fisher’s exact test was used to assess the relationship between physical exams and the mobility of the ulnar nerve. Values of p<0.05 were considered statistically significant.Results:Ulnar nerve hypermobility was identified in 54 (78.3%) of the 69 elbows in throwing side. Meanwhile, hypermobility was 53 (76.8%) in non-throwing side without significant difference, compared to non-throwing side. Elbows with nerve hypermobility did not experience a higher prevalence of subjective symptoms (snapping, pain, and tingling) than did elbows with stable nerves. Provocative physical examination testing for ulnar nerve irritability, however, showed consistent trends toward heightened irritability in hypermobile nerves (p = 0.04 to 0.16). Demographic data and anatomic measurements were similar between the subjects with stable nerves and those with hypermobile nerves. Additionally, all participants did not show decrease of throwing performance.Conclusions:Ulnar nerve hypermobility occurs in over half of the baseball players in throwing and non-throwing sides. Utilizing a standardized sonographic examination, a diagnosis of ulnar nerve hypermobility can be established with substantial interobserver reliability. In baseball players, ulnar nerve hypermobility does not appear to be associated with an increased symptomatology attributable to the ulnar nerve and throwing performance. Anterior transplantation of ulnar nerve may not be needed for baseball players with ulnar nerve neuropathy.

Increased medial laxity of the elbow in preadolescent baseball players with or without medial elbow apophysitis.

BackgroundMedial elbow apophysitis is a traction apophysitis observed in the medial epicondyle of the elbow in preadolescent baseball players. The purpose of this study was to determine the relationship between medial elbow apophysitis and elbow valgus instability in preadolescent baseball players.MethodsThe participants were classified into a control group and an injury group; the injury group included participants diagnosed with a medial elbow injury (inclusion criteria were only symptoms of the elbow joint or positive findings on physical examinations, or both). Elbow valgus instability was assessed by measuring the differences in ulnohumeral joint gapping width, with and without gravity stress induced by weight loading of the forearm using ultrasonography.ResultsThe control and injury groups consisted of 81 and 23 preadolescent baseball players, respectively. In the throwing elbow, valgus instability in the injury group was significantly greater than that in the control group (1.07 vs. 0.57 mm, P = .001). In the non-throwing elbow, valgus instability in the injury group was significantly greater than that in the control group (0.57 vs. 0.37 mm, P = .011). The area under the curve for valgus instability of the throwing elbow was 0.89 mm (95% confidence interval, 0.64-0.77), and the cut-off value for elbow pain appearance was 0.80 mm.ConclusionThe increased elbow valgus instability in the injury group was associated with a medial elbow injury. For the elbow valgus instability of the non-throwing side in the injury group, we considered that players with medial elbow apophysitis inherently have elbow laxity.

Upper Quarter Y-Balance Test in Collegiate Softball Players: Bilateral Arm Comparison and Influence of Reach Order

The upper quarter Y-balance test is an upper extremity, closed kinetic chain assessment that requires individuals to reach in three directions while in a three-point plank position. The upper quarter Y-balance test was performed in 22 collegiate softball players (19.95 ± 1.52 years) to determine the (a) differences between throwing and nonthrowing (NT) sides and (b) influence of reach sequence. While stabilizing on the NT side, participants reached significantly further in the inferolateral direction than the throwing side (NT: 83.7 ± 12.2% arm length; throwing: 80.1 ± 10.5% arm length; p = .03; effect size = −0.57). Altering reach sequence significantly influenced medial reach (p &lt; .01, effect size = 0.66) and composite score (p = .017, effect size = 1.03) when stabilizing on the NT side. Asymmetries in upper quarter Y-balance test in collegiate softball players should be interpreted cautiously, and an ordered test sequence should be consistently followed.

Relationship between glenohumeral internal rotation deficit and shoulder conditions in professional baseball pitchers

Previous studies have reported that glenohumeral internal rotation deficit (GIRD) may increase the risk of throwing-shoulder injuries. The purpose of this study was to analyze the conditions of the throwing shoulder in professional baseball pitchers with GIRD by comparing with those in pitchers without GIRD. In total, 26 male professional baseball pitchers participated in this study. We evaluated passive range of motion (ROM) and isometric muscle strength at internal rotation (IR) and external rotation (ER) at 90° of abduction, as well as the muscle thickness of the supraspinatus (SSP) and infraspinatus (ISP) by ultrasound. The pitchers were divided into 2 groups: those who exhibited a loss of IR of ≥20° in the throwing shoulder (GIRD group) and those who did not (non-GIRD group). In the GIRD group, the total ROM deficit (throwing side - non-throwing side) (P < .001), the muscle thickness ratio (throwing to non-throwing) of the SSP and ISP (P = .017 and P = .014, respectively), and the muscle strength ratio (throwing to non-throwing) of ER (P = .028) were significantly lower than those in the non-GIRD group. In contrast, the muscle strength ratio (throwing to non-throwing) of IR was significantly higher in the GIRD group than in the non-GIRD group (P = .0064). We have shown that GIRD has significant correlations with several conditions, such as atrophy of the SSP and ISP, weakness of ER strength, enhancement of IR strength, limitation of total ROM, and throwing side, all of which could be important factors for throwing-shoulder injuries.

Comparison of Radiographic and Ultrasonographic Findings of Medial Elbow Laxity in High School Baseball Players

Background: Although ultrasonography has been used to assess medial elbow laxity, its usefulness has not yet been confirmed. objective: The aim of this study were to assess medial elbow laxity in high school baseball players based on measurements of the medial joint space (MJS) of the elbow using ultrasonography and radiography and to investigate the correlation between these assessments. Methods: Thirty-two high school baseball players participated in this study. Fourteen players (44%) were diagnosed with Ulnar Collateral Ligament (UCL) injury. Valgus stress was applied to the elbow by gravity during ultrasonographic and radiographic assessments, and the MJS was measured. The MJS of the throwing side was compared with that of the non-throwing side, and the increase in the MJS of the throwing side was determined. The correlation between ultrasonographic and radiographic assessments was investigated and the usefulness of these assessments for the diagnosis of UCL injury was evaluated. Results: A moderate correlation was found between the ultrasonographic and radiographic assessments of the MJS of the throwing side (correlation coefficient=0.547, P=0.0009). Furthermore, a weak correlation was found for the increase in MJS (correlation coefficient=0.348, P=0.0505), although it was not significant. The comparisons of the radiographic assessments between the UCL injury and non-UCL injury groups showed a significant difference in both the MJS of the throwing side (P=0.0068) and the increase in the MJS (P=0.02), although no difference was found using ultrasonography. Conclusion: Ultrasonography, similar to radiography, is useful for assessing medial elbow laxity. While radiography is useful for diagnosing UCL injury.

Throwing can Increase the Stiffness of the Scalene Muscle

Objectives:Thoracic outlet syndrome (TOS) has been reported as a set of symptoms due to the compression of the brachial plexus and subclavian vessels in the region of the thoracic outlet1. As a type of TOS, scalenus anticus syndrome involves the compression of the brachial nerves as they pass through the interval surrounded by the anterior and middle scalene muscles, and the first rib bone or cervical rib2. Recently, exercise-induced TOS is becoming more common in athletes, especially for those who perform repetitive overhead and hyperabduction maneuvers with upper limbs, such as baseball players. However, the effect of throwing on the stiffness of the scalene muscles is unknown. Thus, the purpose of this study was to quantitatively measure the stiffness of the scalene muscles using real-time shear wave elastography (SWE). The stiffness of scalene muscles was hypothesized to increase for the throwing side of baseball players.Methods:Thirty college baseball players (age range 19 to 21 years) were included for this study. Ultrasonic SWE with a 2-10 MHz linear array probe transducer (Aixplorer; SuperSonic Imagine, Aix-en-Provence, France) was used to assess the stiffness of the anterior and middle scalene muscles. Each participant was sited. The measurements were performed in two arm positions; 1) adducted and neutral rotation of the shoulder 2)90 degree of abduction and external rotation of shoulder with elbow flexed to simulate a clinical examination known as Roos test3. In both of the arm positions, the transducer was positioned just superior to the clavicular bone, parallel to its axis. Transducer was moved superiorly and tilted to visualize the superior surfaces of the anterior and middle scalene muscles parallel to the surface of the fifth cervical nerve simultaneously (Figure 1A). In this position, shear wave elastography was performed to measure the elasticity of each scalene muscle as its stiffness. Each muscle was divided into superior and deep areas. In both areas of each muscle, three 3mm-diameter circles were set to measure the elasticities of the scalene muscles and its averaged data in each area was defined as each stiffness (Figure 1B). A repeated-measures analysis of variance (ANOVA) was used to compare the elasticity of superior and deep areas in anterior and middle scalene muscles in throwing and non-throwing side. Values of p<0.05 were considered statistically significant.Results:For the throwing side, higher stiffness was found in the deep part of the middle scalene muscle compared to the superior and deep parts of the anterior scalene muscle with an adducted and neutrally rotated shoulder (p=0.0433). Moreover, the muscle stiffness was significantly higher in the superior and deep part of the middle scalene muscle than in the superior and deep parts of anterior scalene muscle in an abducted and externally rotated position of shoulder (p =0.00187). Meanwhile, no significant difference was found in the anterior and middle scalene muscles for the non-throwing side in both arm positions.Conclusion:In professional athletes with TOS who experienced surgical treatment, moderate to severe hypertrophy of the anterior scalenus muscles has been reported to be found4. Meanwhile, although the stiffness of the scalene muscles can be also related to the compression on the brachial plexus and on subclavian vessels in the region of the thoracic outlet, its quantitative measurements in the scalene muscles has not been reported. In this study, at throwing side, the muscle stiffness significantly increased in the superior area of middle scalene muscle in throwing side. While no contribution was identified in the scalene muscles at non-throwing side. As a result, repeat throwing motion can increase the stiffness of the middle scalene muscle. As a result, the brachial plexus and/or the subclavian artery could be compressed at the interscalene triangle. Throwing athletes with TOS should be treated, considering the stiffness of the middle scalene muscle, even conservative or surgical treatment. Our study was the first study to evaluate the effects of throwing on the stiffness of the scalene muscles in throwing athletes. Repetitive throwing motion can affect the stiffness of middle scalene muscle. Reduction of the middle scalene muscle should be considered to treat throwing athlete who has TOS.Figure 1.