Protective Effects of Extracorporeal Shockwave Therapy on the Degenerated Meniscus in a Rat Model.

BACKGROUND: Loss of meniscal function in association with degenerative changes affects the development and progression of knee osteoarthritis, for which there is currently no effective treatment. Extracorporeal shockwave therapy (ESWT) is an established treatment for musculoskeletal disorders. However, the therapeutic effect of ESWT on meniscal degeneration remains unclear. PURPOSE: To evaluate the therapeutic effect of ESWT on the degenerated meniscus in an anterior cruciate ligament transection (ACLT) model. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve-week-old male Wistar rats were randomly assigned to 3 groups (normal, ESWT-, and ESWT+). Unilateral ACLT of the right knee was performed in the latter 2 groups. At 4 weeks after ACLT, the ESWT+ group received 800 shockwave impulses at an energy flux density of 0.22 mJ/mm2 in a single session. Histological changes were examined in the posterior portion of the medial meniscus after ESWT (n = 15 per group). Real-time polymerase chain reaction (PCR) was performed after ESWT (n = 5 per group) to analyze the expression of connective tissue growth factor/CCN family member 2 (CTGF/CCN2), sex determining region Y-box 9, vascular endothelial growth factor α, aggrecan, collagen type 1 alpha 2, and collagen type 2 alpha 1 (Col2α1). Immunohistochemistry was used to analyze the expression of CTGF/CCN2 and Ki-67 (n = 5 per group) after ESWT. RESULTS: The meniscal histopathological score at 4 weeks after ACLT was significantly higher than that in the normal group, and the score in the ESWT+ group was significantly lower than that in the ESWT- group at 4 and 12 weeks after ESWT. Real-time PCR revealed that the mRNA expression of CTGF/CCN2 and Col2α1 decreased 4 weeks after ACLT. In the ESWT+ group, real-time PCR revealed that the mRNA expression of CTGF/CCN2 increased 24 hours after ESWT, and the expression of Col2α1 increased 4 weeks after ESWT (all significant data were P < .05). The ratio of CTGF/CCN2-positive cells and Ki67-positive cells was significantly higher in the ESWT+ group after ESWT. CONCLUSION: The present study revealed that ESWT might suppress ACLT-induced meniscal degeneration by stimulating cartilage repair factors and inducing collagen type 2. CLINICAL RELEVANCE: ESWT can be an effective treatment to protect the degenerated meniscus in a rat model of ACLT.

Relationship between Nontraumatic Shoulder Disorders and Neuropathic Pain: Retrospective Observational Analyses of Clinical Features and Background Factors.

Background: Accurate identification of neuropathic pain is necessary for appropriate treatment; however, the relationship between nontraumatic shoulder disorders and neuropathic pain remains unknown. Therefore, this retrospective observational study aimed to investigate the relationship, features, background factors, and prevalence of neuropathic pain among patients with nontraumatic shoulder disorders. Methods: We evaluated 198 patients who visited our outpatient clinic, which specializes in shoulder disorders, from April 2015 to March 2016. The patients' age, sex, affected side, diagnosis, and pain duration were recorded, and the results of physical examination, including passive range of motion, impingement sign, and muscular strength assessments, were analyzed. The presence of neuropathic pain was assessed using the painDETECT questionnaire. Participants were divided into two groups according to the presence of neuropathic pain. Pain intensity was assessed using a visual analog scale, and the patient's mental status was assessed using the short-form McGill Pain Questionnaire and Hospital Anxiety and Depression Scale. The scores were compared between the groups. Results: Neuropathic pain was observed in 7.6% of patients. The visual analog scale score for pain, short-form McGill Pain Questionnaire score, and Hospital Anxiety and Depression Scale score were significantly associated with the presence of neuropathic pain in the univariate analysis. Patient background factors and physical function were not associated with the presence of neuropathic pain. The prevalence of neuropathic pain in patients with frozen shoulder was 33.3%, which was significantly higher than that in patients with other shoulder disorders. Conclusion: The occurrence of neuropathic pain may aggravate pain in patients with nontraumatic shoulder disorders. Neuropathic pain was not a rare condition in patients with nontraumatic shoulder disorders, particularly in those with frozen shoulder. The coexistence of neuropathic pain cannot be determined from background factors or physical function. Accurate diagnosis of neuropathic pain is essential in patients with nontraumatic shoulder disorders.

Triamcinolone acetonide with arthroscopic capsular release for frozen shoulder promotes early recovery of shoulder abduction.

Background: Current treatment options for frozen shoulder are not established as the standard-of-care. The condition may resolve without intervention, but symptoms may persist despite treatment. Frozen shoulder is associated with inflammatory reactions that can reduce quality of life. Our aim was to determine whether triamcinolone acetonide, an immunosuppressive steroid, improved functional recovery when administered after arthroscopic capsular release (ACR) for frozen shoulder. Methods: We selected participants using inclusion and exclusion criteria designed to reduce the impact of potential confounding factors. Under general anesthesia, we performed ACR followed by manipulation to ensure adequate range of motion (ROM) and wound closure. In the steroid treatment group, we injected triamcinolone acetonide into the glenohumeral joint immediately prior to wound closure. The follow-up period was six months. To determine the efficacy of steroids in improving overall post procedure functional recovery we statistically analyzed data from various qualitative and quantitative variables. Results: Our study consisted of 22 patients with frozen shoulder, 11 in each of the surgery-only and surgery with steroid injection groups. There were no significant differences between groups in the demographic data of the study participants. We observed significantly greater improvements in abduction ROM in the steroid treatment group than in the surgery-only group, at three and six months post treatment. Improvements in other movement parameters were similar in both groups. The steroid-treated group had a significantly higher numerical rating scale score for night pain at three months post treatment than the surgery-only group. Conclusions: Postoperative steroid treatment led to early recovery of the abduction ROM in patients with frozen shoulder. Hence, the current standard-of-care protocol for frozen shoulder and other similar conditions requiring surgical intervention should include this type of treatment. Therapeutic reduction in the inflammatory response following ACR can significantly improve prognosis and quality of life.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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 6.3 mm vs 5.7 mm, axial 8.2 mm vs 7.5 mm, 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. CONCLUSION: Sonographic appearance of the PQ might be associated with elbow joint conditions in high school baseball players.

Arthroscope-assisted reduction of humeral head impression fracture: a case report.

We experienced a case of humeral head impression fracture accounting for approximately 20% of the anterior articular surface. Open reduction and internal fixation of the proximal humeral fracture combined with arthroscope-assisted reduction and internal fixation of the humeral head impression fracture were performed, and good clinical and radiographic outcomes were obtained. Untreated impression fracture may be a potential risk for subluxation or osteoarthritis. However, our arthroscopic approach is minimally invasive and allows for the prevention of these risks.

Shoulder stretching versus shoulder muscle strength training for the prevention of baseball-related arm injuries: a randomized, active-controlled, open-label, non-inferiority study.

Glenohumeral internal rotation deficit (GIRD) and weakness in prone external rotation are risk factors for shoulder and elbow injuries in high school baseball pitchers. While a shoulder-stretching prevention program to improve GIRD decreases the injury rate, the effects of external rotation strength remain unclear. This non-inferiority (NI) study investigates the hypothesis that external rotation strength training is not inferior to sleeper stretching for shoulder and elbow injury prevention in high school baseball pitchers. Participants were randomly allocated to the stretching (n = 62; active control group) and muscle-training (n = 51) groups. Specific exercises were performed each night. Elbow and shoulder injuries were monitored for 150 days. Kaplan-Meier survival curves were generated, and the hazard ratios (HRs) for injury occurrence were calculated using multivariate Cox regression. The log-rank test was used to compare the injury-free time. A one-sided NI test using a fixed NI margin was performed (significance level, P = 0.025). The injury rates were 22.6% (n = 14) in the stretching group and 9.8% (n = 5) in the muscle-training group. The muscle-training group had a lower injury rate (P < 0.001) and a lower risk of injury than the stretching group (HR = 0.489). Therefore, external rotation muscle strength training is not inferior to stretching for preventing baseball-related arm injuries.

Risk factors for shoulder osteoarthritis with rotator cuff tear in the elderly general population.

HYPOTHESIS AND/OR BACKGROUND: The relationship between shoulder osteoarthritis (OA) and rotator cuff tear (RCT) is unclear. We hypothesized that there is a difference between the pathogenesis of OA complicating RCT and that of RCT complicating OA. In this study, our primary objective was to determine the prevalence of shoulder OA without RCT, RCT without OA, and OA with RCT in the general older population. Our secondary objective was to identify risk factors for the association with OA+RCT in shoulder OA alone or RCT alone, respectively. METHODS: We enrolled patients from the public health checkup conducted in Gunma prefecture (Japan) in 2014. Subjects' shoulder pain at rest, during motion, and at night was evaluated using a questionnaire. Moreover, active and passive range of motions (ROMs) in flexion, abduction, and external rotation were measured. For RCT parameters, we evaluated as no tear, partial-thickness supraspinatus (SSP) tear, full-thickness SSP tear, and SSP-infraspinatus tears. For further analysis, the shoulders were divided into three groups according to the presence of RCT and/or OA: OA, RCT, and OA + RCT groups. Risk factors for OA + RCT were identified in a logistic regression analysis. RESULTS: Overall, 944 of 1148 shoulders were eligible for inclusion. The prevalence rates of shoulder OA, RCT, and OA + RCT were 5.8%, 21.1%, and 4.2%, respectively. Furthermore, 650 shoulders were excluded, and 55, 199, and 40 shoulders had OA, RCT, and OA + RCT, respectively. There were significant differences for age, ROM of active external rotation, strength of abduction, external rotation, and morphology of the rotator tears. However, there were no significant differences for pain visual analog scale score, passive ROM, Simple Shoulder Test, and grades of OA. Older age decreased active ROM in external rotation, and the presence of both subscapularis and SSP-infraspinatus tears was a risk factor for the association of OA with an RCT shoulder. Older age, weaker power in external rotation, and affected dominant side were risk factors for the association of RCT with an OA shoulder. DISCUSSION AND/OR CONCLUSION: This study is the first to report risk factors by considering both shoulder OA and RCT in the general population. Our findings will be useful for the treatment and management of OA and RCT as well as for the prevention of these conditions in the older adults.

The Relationship Between Dynamic Balance Ability and Shoulder Pain in High School Baseball Pitchers.

BACKGROUND: Dynamic balance is essential for pitching motion because pitching kinematics requires whole body coordination. The Star Excursion Balance Test (SEBT) and the Y balance test (YBT) evaluate dynamic balance quantitatively. There are some reports that investigated the relationship between SEBT/YBT and pain in upper and lower extremities, but there is no study among high school baseball pitchers. HYPOTHESIS: Dynamic balance deficiency is associated with shoulder pain among high school baseball pitchers. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 4. METHODS: A total of 259 male high school pitchers who participated in the preseason medical checkups were included in the study. YBT was used to measure their dynamic balance. The participants completed a questionnaire which asked if they were currently experiencing shoulder pain. RESULTS: Twenty-two pitchers had shoulder pain during the preseason medical checkups. In the YBT, the posterolateral balance while standing with the axis leg as well as the posteromedial and posterolateral balance while standing with the step leg were significantly lower in the pain group than in the nonpain group (P = 0.05, 0.04, and 0.001, respectively). A logistic regression analysis showed that posterolateral balance when standing with the step leg was an independent risk factor for current shoulder pain (P = 0.04, odds ratio 0.942, 95% CI 0.892-0.996). CONCLUSION: The dynamic balance of high school baseball pitchers with shoulder pain was lower than that of participants without shoulder pain. In particular, posterolateral direction with the step leg standing was significantly related to shoulder pain. CLINICAL RELEVANCE: Among high school baseball pitchers, decreased dynamic balance was related to current shoulder pain. YBT maybe recommended in preseason medical checkups for high school baseball pitchers.

Delayed detection of passive motion in shoulders with a rotator cuff tear.

The aim of this study was to test whether or not the threshold to the detection of passive motion (TTDPM) and passive joint position sense on the affected shoulder of patients with rotator cuff tear (RCT) was impaired compared to those on the unaffected side and to investigate the relationship between the tear size and changes in the TTDPM and passive joint position sense induced by RCT. This study included 21 patients with unilateral RCT before arthroscopic rotator cuff repair. To investigate proprioception in this study, we measured the TTDPM and passive joint position sense in abduction and external rotation using an isokinetic dynamometer. The tear size was evaluated intraoperatively under direct arthroscopic visualization. The TTDPM in abduction and external rotation was significantly longer on the affected side than on the unaffected side. However, the angular absolute error in passive joint position sense in abduction and external rotation was not significantly different between the limbs. A comparison according to the tear size impaired proprioception of the TTDPM in the larger tear group showed significantly longer values than in the smaller group. There was impaired proprioception of TTDPM in patients with RCT, and the impaired proprioception was related to tear severity. Impaired proprioception of TTDPM may inhibit consistent muscle recruitment to achieve precise control. Our results suggest that clinicians should consider proprioceptive exercises for impaired proprioception in their treatment for conservative or postoperative patients.

Neuroplasticity Caused by Peripheral Proprioceptive Deficits.

PURPOSE: Proprioceptive feedback is crucial for motor control and stabilization of the shoulder joint in everyday life and sports. Shoulder dislocation causes anatomical and proprioceptive feedback damage that contributes to subsequent dislocations. Previous recurrent anterior shoulder instability (RSI) studies did not investigate functional neuroplasticity related to proprioception of the injured shoulder. Thus, we aimed to study the differences in neuroplasticity related to motor control between patients with RSI and healthy individuals, using functional magnetic resonance imaging, and assess the effects of peripheral proprioceptive deficits due to RSI on CNS activity. METHODS: Using passive shoulder motion and voluntary shoulder muscles contraction tasks, we compared the CNS correlates of proprioceptive activity between patients having RSI (n = 13) and healthy controls (n = 12) to clarify RSI pathophysiology and the effects of RSI-related peripheral proprioceptive deficits on CNS activity. RESULTS: Decreased proprioception-related brain activity indicated a deficient passive proprioception in patients with RSI (P < 0.05 family-wise error, cluster level). Proprioceptive afferent-related right cerebellar activity significantly negatively correlated with the extent of shoulder damage (P = 0.001, r = -0.79). Functional magnetic resonance imaging demonstrated abnormal motor control in the CNS during voluntary shoulder muscles contraction. CONCLUSION: Our integrated analysis of peripheral anatomical information and brain activity during motion tasks can be used to investigate other orthopedic diseases.

Association Between Upper-Extremity Health Condition and Depressive Status in an Elderly General Population.

BACKGROUND: This study was designed to investigate whether psychological status is associated with upper-extremity health status in an elderly general population. METHODS: Using Quick Disabilities of the Arm, Shoulder, and Hand of the Japanese Society for Surgery of the Hand (QuickDASH-JSSH), we evaluated 200 Japanese elderly people (76 men, 124 women; mean age, 71.6 years, 60-98 years) to assess their upper-extremity-specific health status. Each had completed a self-administered questionnaire including gender and dominant hand items. As an indicator of hand muscle function, we measured their bilateral hand grip. Study participants were assessed for depressive symptoms using the Geriatric Depression Scale Short-Japanese Version (GDS-S-J). Statistical analyses were applied to clarify associations between self-assessed upper-extremity dysfunction and screening results for depressive symptoms in an elderly general population. RESULTS: Those reporting no complaint of an upper extremity were 72 (36 men and 36 women) (36.0%). The GDS-J score was found to have significant positive correlation with age (r = 0.20, P= 0.0045) and the QuickDASH score (r = 0.25, P = 0.0004). The GDS-J score was found to have significant negative correlation with dominant grip (r = -0.15, P = 0.04) and non-dominant grip strength (r = -0.21, P = 0.004). For all participants, multiple regression analysis revealed the QuickDASH score as associated with the GDS-J score. CONCLUSION: Self-administered upper-extremity health condition as assessed using QuickDASH is correlated with depressive symptoms in elderly people. Objective pathophysiology and subjective illness behavior must be identified in daily clinical practice. A biopsychosocial approach must be used when advising and treating patients.

Reciprocal inhibition improves posterior shoulder tightness and shoulder range of motion in youth baseball players.

BACKGROUND: The aim of this study was to evaluate the efficacy of reciprocal inhibition for posterior shoulder tightness (PST), internal rotation at 90° abduction (ABIR) limitation, and subacromial impingement in elementary and junior high school baseball players. METHODS: The present study included 290 elementary school and junior high school baseball players who were members of an organized baseball team and attended a medical checkup in 2014. Seventeen participants were excluded because they were left-handed. We applied a sit-up exercise as a tool of reciprocal inhibition to all participants. Before and after the sit-up exercise, we evaluated the shoulder range of motion (ROM) in external rotation at 90° abduction (ABER), ABIR, and horizontal flexion (HF) in both shoulders and the prevalence of subacromial impingement in the dominant shoulder. We defined PST as a ≧15°decrease in the HF angle of the dominant shoulder in comparison to the nondominant shoulder before the sit-up exercise and divided participants into two groups (the PST group and the non-PST groups). An independent t-test was performed to compare the shoulder ROM, and a chi-squared test was performed to compare the prevalence of subacromial impingement between the two groups. A dependent t-test was performed to compare intragroup changes in the shoulder ROM. The McNemar test was performed to compare intragroup changes in the prevalence of subacromial impingement. RESULTS: Fifty-six of 273 participants had PST in the initial examination. The initial examination revealed that the ROM of ABIR and HF in the dominant shoulder were significantly lower in the PST group than those in the non-PST group, whereas the ROM of ABER and total arc were significantly higher in the PST group. The prevalence of subacromial impingement in the PST group was significantly higher than that in the non-PST group. The sit-up exercise improved ABER, ABIR, total arc, HF, and the prevalence of subacromial impingement in both groups. However, the amount of ROM change did not differ between the two groups for any parameter with the exception of HF. CONCLUSION: The presence of PST affects the prevalence of subacromial impingement but was not related to the loss of ABIR or the prevalence of pathological glenohumeral internal rotation deficit. The sit-up exercise, as reciprocal inhibition, can transiently improve the prevalence of subacromial impingement via the improvement of PST.

Risk Factors for Throwing-Related Shoulder and Elbow Pain in Adolescent Baseball Players: A Prospective Study of Physical and Developmental Factors.

BACKGROUND: Throwing-related shoulder and elbow pain continues to be reported among adolescent baseball players. Few prospective studies have specifically examined the association between throwing-related shoulder and elbow pain and physical and developmental changes. PURPOSE: To evaluate the changes in physical and developmental characteristics during 1 year with respect to throwing-related shoulder and elbow pain in adolescent baseball players. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: This 1-year prospective follow-up study investigated 164 baseball players aged 7 to 13 years. Player data (age, height, weight, field position, and pitch count), lower extremity muscle tightness, and range of motion (ROM) of the shoulder, elbow, and hip joints were assessed during the 2016 and 2017 preseason medical examinations. After the 2016 season, the participants completed questionnaires related to throwing-related shoulder and elbow pain, defined as an inability to play for ≥1 week because of elbow or shoulder difficulties. For study participants with and without throwing-related shoulder or elbow pain during the 2016 season, we conducted univariate and multivariate logistic regression analysis to identify risk factors for throwing-related shoulder or elbow pain. RESULTS: Overall, 21 players (12.8%) reported a shoulder pain episode, 56 players (34.1%) had an elbow pain episode, and 70 players (42.7%) reported having experienced shoulder and/or elbow pain during the 2016 season. In multivariate logistic regression analysis, (1) shoulder pain was associated with 2016 preseason height (odds ratio [OR], 1.06; 95% CI, 1.01-1.11; P = .01) and change in dominant-side elbow extension ROM from 2016 to 2017 (OR, 1.12; 95% CI, 1.02-1.24; P = .02); (2) elbow pain was associated with change in weight from 2016 to 2017 (OR, 1.21; 95% CI, 1.04-1.41; P = .014); and (3) throwing-related shoulder and/or elbow pain was associated with greater 2016 preseason height (OR, 1.04; 95% CI, 1.003-1.68; P = .03) and an increase in height from 2016 to 2017 (OR, 1.17; 95% CI, 1.01-1.35; P = .03). CONCLUSION: Our results indicated that adolescent baseball players who were taller in the preseason and those with an increase in height over the 1-year study period faced significant risks for developing throwing-related shoulder and/or elbow pain.

Four-year trend in shoulder and elbow injuries in competitive-level high school baseball pitchers: a repeated cross-sectional survey.

BACKGROUND: Shoulder and elbow injuries are the main cause of throwing disability among high school baseball pitchers. However, longitudinal studies on shoulder and elbow injuries among competitive-level high school baseball pitchers have been insufficient. This study aimed to investigate shoulder and elbow injuries in competitive-level high school baseball pitchers over a four-year period and elucidate the effects of implementing medical checkups on the incidence of shoulder and elbow injuries. METHODS: Five hundred fifty-two high school baseball pitchers, who received preseason medical checkups from February 2012 to February 2015, were enrolled in this study. Shoulder and elbow injuries occurring during the season after medical checkups were prospectively evaluated by a postseason questionnaire. Pitchers who were not able to pitch for >7 days owing to shoulder or elbow pain were defined as having shoulder and elbow injuries during the season. The incidence rates of shoulder and elbow injuries during the seasons were calculated and compared over the 4-year period. RESULTS: Ninety-six percent of medical checkup participants were included in the study. The mean questionnaire collection rate of the prospective study was 71.6% (range: 67.7-78.9%). The incidence of shoulder and elbow injuries significantly decreased from 20.0% in 2012 to 7.7% in 2015 (P = .013). CONCLUSION: The four-year trend in the incidence of shoulder and elbow injuries in competitive-level high school baseball pitchers was evaluated. The incidence of shoulder and elbow injuries during the season significantly decreased with a linear downward trend during the survey period after the implementation of medical checkups.

Risk factor for elbow symptom manifestation in young baseball players with asymptomatic medial elbow abnormalities: a prospective cohort study.

Asymptomatic elbow abnormalities are relatively common in young baseball players, but the factors responsible are unclear. To prospectively identify risk factors related to symptom manifestation in asymptomatic elbow abnormalities, we recruited 573 baseball players (age: 7-14 years) at a pre-participation medical/physical examination in the preseason who were right-handed and had asymptomatic medial elbow abnormalities on ultrasound (US). Baseline preseason and postseason participant characteristics were assessed. A "symptomatic" elbow was defined as an elbow with medial elbow joint problems that prevented ball throwing for ≥ 8 days. After exclusions, 82 players were enrolled, of whom 22 (26.8%) developed a symptomatic elbow. In univariate analyses, the external and internal rotation strengths of the dominant shoulder were significantly greater in the symptomatic group than in the asymptomatic group (P = 0.021). Multivariate logistic regression analysis showed that the internal rotation strength of the dominant shoulder was a significant independent risk factor (odds ratio = 1.091, P = 0.027) for developing a symptomatic elbow. In young asymptomatic baseball players with abnormalities in the medial elbow region of the dominant arm on US, stronger preseason internal rotation strength of the dominant shoulder was a significant independent risk factor for the development of a "symptomatic" elbow.

An analysis of pre-season risk factors for low back injury in high-school baseball pitchers: a prospective study.

Pitching motion requires whole-body coordination; therefore, poor control of the lower extremities, pelvis and trunk may cause shoulder and elbow injuries. However, few studies have described the relationship between the shoulder joint function and low back injury in high-school baseball pitchers. A total of 128 healthy high school pitchers underwent pre-season medical checkups, where their shoulder range of motion and shoulder strength were measured. The participants completed a self-recorded daily questionnaire regarding the presence of low back pain. Pitchers were divided into injured and non-injured groups. Low back injury was observed in 13 participants (13.4%). In the injured group, horizontal adduction on the dominant shoulder was significantly less than in the non-injured group. A logistic regression analysis showed that horizontal adduction on the dominant side was a significant independent risk factor for low back injury during the season. It is important to recognize that restriction of the shoulder function not only causes shoulder and elbow injuries but can also risk low back injury.

Asymptomatic Medial Elbow Ultrasound Abnormality in Youth Baseball Players Is an Independent Risk Factor for Elbow Injury: A Prospective Cohort Study.

BACKGROUND: Youth baseball players who experience elbow pain during the season frequently exhibit radiographic elbow abnormalities. However, it is unknown whether asymptomatic elbow abnormalities are risk factors for in-season elbow injuries. PURPOSE: To determine whether the preseason presence of asymptomatic medial epicondyle apophysitis is a risk factor for in-season elbow injuries in youth baseball players. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Youth baseball players (N = 210; age range, 7-12 years) with no pain or history of injury in their throwing arms underwent preseason evaluations that included shoulder and elbow range of motion measurements, shoulder muscle strength testing, and ultrasound elbow scans with a multifrequency 13-MHz linear array transducer. Over 1 year of play, the players and their parents maintained daily elbow pain diaries. Elbow injuries were defined as medial elbow symptoms that prevented ball throwing for ≥8 days. RESULTS: The preseason ultrasound evaluation revealed medial epicondyle apophysitis in 59 players. In the year following, elbow injuries occurred in 17 (28.8%) players with preseason medial epicondyle apophysitis and 18 (11.9%) players without apophysitis. Independent predictors of elbow injuries were preseason medial epicondyle apophysitis (odds ratio [OR], 2.488; 95% confidence interval [CI], 1.152-5.376; P = .02) and deficits of abduction (ABD) and external rotation of the dominant shoulder (OR, 0.963; 95% CI, 0.936-0.992; P = .012). CONCLUSION: Asymptomatic medial epicondyle apophysitis and ABD and external rotation deficits in the dominant shoulder were risk factors for elbow injuries in 7- to 12-year-old youth baseball players. These findings may aid in the design of programs to prevent elbow injuries in this population.

Relationship between the Lower Limb Function and Shoulder and Elbow Injuries in Elementary School Baseball Pitchers.

OBJECTIVES: We aimed to examine the relationship between the hip range of motion (ROM) and ankle ROM and throwing-related shoulder and elbow injuries in elementary school baseball pitchers. METHODS: This retrospective comparative study (Level of evidence: Level III) included 195 baseball pitchers (mean age 10.8±1.0 years, range 8-12 years). All pitchers underwent physical function measurements, including height, weight, shoulder strength, and hip and ankle ROM. Shoulder and elbow injury was defined as shoulder and elbow pain that the pitchers had been aware of in the past or at the time of medical checkups. The results for the injured and non-injured groups were then compared. RESULTS: The shoulder ROM and strength in the injured and non-injured groups did not differ to a statistically significant extent. The hip external rotation on the dominant side (injured vs. non-injured: 48.9±11.1° vs. 53.3±9.7°, P<0.01), the hip internal rotation on the non-dominant side (injured vs. non-injured: 36.6±12.0° vs. 40.9±11.0°, P=0.01), and ankle plantar flexion on the non-dominant side (injured vs. non-injured: 52.0±6.8° vs. 54.3±6.7°, P=0.02) were significantly smaller in the injured group than in the non-injured group. CONCLUSIONS: The hip external rotation ROM on the dominant side and the hip internal rotation and ankle plantar flexion on the non-dominant side were significantly lower in the injured group than in the non-injured group. These results may suggest measures to reduce the incidence of elbow and shoulder injuries in elementary school baseball pitchers.

Ankle dorsiflexion deficit in the back leg is a risk factor for shoulder and elbow injuries in young baseball players.

The relationship between ankle joint function and throwing-related injuries has not been demonstrated. We hypothesized that limited ankle joint range of motion (ROM) was related to risk factors for shoulder and elbow injuries in young baseball players. This 12-month prospective cohort study evaluated the age, height, weight, playing position, shoulder, elbow, and ankle function of 228 enrolled baseball players. Shoulder and elbow injuries were tracked during the season. Univariate and multivariate analyses were performed to identify risk factors for shoulder and elbow injuries among participants divided into non-injured and injured groups. Univariate analysis showed that age, height, weight, ROM of elbow flexion in the dominant arm, muscle strength ratio of shoulder abduction, and the likelihood of being a pitcher or a catcher were significantly greater in the injured group than in the non-injured group. ROM of shoulder abduction-external/internal rotation, shoulder total arc on the dominant arm, ankle joint dorsiflexion, and plantar flexion on the back (non-lead) and front (lead) legs were significantly less in the injured group than in the non-injured group. In conclusion, ROM dorsiflexion deficits in the back leg, shoulder abduction-external rotation in the dominant arm, ROM increase in elbow flexion on the dominant side, older age, and being a pitcher were significant independent risk factors for injury.

Relationship between upper limb injuries and hip range of motion and strength in high school baseball pitchers.

We aimed to examine the relationship between hip range of motion (ROM) and abduction strength and throwing-related shoulder/elbow injuries in high school baseball pitchers. The study included 135 baseball pitchers. We asked them to fill out a questionnaire at the checkups, that included the dominant arm and the years of baseball experience. To avoid a confirmation bias, the examiners were blinded to the participants' hand dominance. All players underwent physical function measurements, such as height, weight, shoulder and hip strength, and shoulder and hip ROM. Shoulder and elbow injury was defined as shoulder and elbow pain that the patient had been aware of in the past 3 years. The results of injured and non-injured pitchers were compared. Eighty-five pitchers had experienced a shoulder or elbow injury in the past 3 years. The shoulder ROM and strength in the injured and non-injured groups did not differ to a statistically significant extent. The hip external rotation ROM on the dominant side, the hip abduction strength on the non-dominant side, and the hip abduction strength on the dominant side were significantly lower in the injured group than in the non-injured group. The results may contribute to reducing the incidence of these injuries.