Pronation and palmar pinch improve the stability of the medial elbow joint space in high school baseball pitchers.

HYPOTHESIS: We aimed to investigate the contributions of grip, pronation, and pinch to stabilization of the medial elbow joint space; examine their relationship with muscle strength; and assess the effect of stabilization on the medial elbow joint space in baseball pitchers. METHODS: In this controlled laboratory study, we measured the medial elbow joint space using ultrasound during the following conditions: unloading; loading; and loading with grip, pronation, and pinch. To evaluate changes in the medial elbow joint space as a result of various conditions, 1-way repeated-measures analysis of variance and post hoc analysis for multiple comparisons were performed. To investigate whether strong or weak muscle strength improved the medial elbow joint space during the loaded condition, Pearson correlation analysis was performed. Finally, a post hoc power analysis was performed. RESULTS: We enrolled 121 pitchers. The medial elbow joint space in the loaded condition, loaded condition with full grip, and loaded condition with full pinch was significantly larger than that in the unloaded condition. The medial elbow joint space in the loaded condition with full grip, loaded condition with full pronation, and loaded condition with full palmar pinch was significantly smaller than that in the loaded condition. A post hoc power analysis showed that the power of the 1-way repeated-measures analysis of variance was 100%. The strengths of the full grip and palmar pinch were significantly correlated with a reduced gap distance of the medial elbow joint space (P < .001 for both). CONCLUSION: In high school baseball pitchers, pronation and palmar pinch contraction significantly improved the gap distance of the medial elbow joint space in the loaded condition and during grip contraction. Moreover, the grip and palmar pinch strengths were significantly correlated with stabilizing effects on the medial elbow joint space.

Intraoperative neuromonitoring during reverse shoulder arthroplasty.

BACKGROUND: The aim of this study was to evaluate the risk of nerve injury with neuromonitoring during reverse total shoulder arthroplasty. MATERIALS: This study included 15 shoulders of 15 patients (11 females and 4 males) who underwent reverse total shoulder arthroplasty. The mean age was 74.8 ± 4.4 years. Nine shoulders had cuff tear arthropathy, 4 had massive rotator cuff tears, 2 had osteoarthritis, and 1 had rheumatoid arthritis. The somatosensory evoked potentials of the median nerve, transcranial motor evoked potentials, and free-electromyograms from 6 upper-extremity muscles were measured intraoperatively. We defined a nerve alert as 50% amplitude attenuation or 10% latency prolongation of the somatosensory evoked potentials and transcranial motor evoked potentials and sustained neurotonic discharge on free-electromyogram. RESULTS: Thirty-one alerts were recorded in 11 patients. The axillary nerve was associated with 17 alerts. Eleven alerts occurred during the glenoid procedure and 5 alerts occurred during the humeral procedure. One patient who did not recover from the alert of the axillary nerve had clinically incomplete paralysis of the deltoid muscle. CONCLUSION: The present findings suggest that the axillary nerve was the nerve most frequently exposed to the risk of injury, especially during glenoid and humeral implantation.

The prevalence of elbow osteoarthritis in Japanese middle-aged and elderly populations: the relationship between risk factors and function.

BACKGROUND: The aim was to investigate the prevalence of elbow osteoarthritis (OA) in populations aged 40 years or older and to clarify the risk factors and their relationship with elbow function. METHODS: The respondents were 354 residents of a single village who underwent general medical examinations in April 2016. The mean age was 67.2 years (range, 40-93 years), and 222 respondents (62.7%) were women. Anteroposterior radiographs of the bilateral elbow joints were obtained, and the subjects were classified into 4 groups (non-OA, mild OA, moderate OA, and severe OA) according to the modified Kellgren-Lawrence scale. With respect to risk factors for elbow OA, a logistic regression analysis was performed. RESULTS: Elbow OA was detected in 55.0% of the elbows. The prevalence of symptomatic elbow OA was 22.6%, and no correlation between elbow OA and daily function was observed. The risk of elbow OA increased according to age, with odds ratios for those in their 50s, 60s, 70s, and 80s or older against those in their 40s of 12.99, 11.26, 14.45, and 26.85, respectively. In addition, male sex and a history of elbow trauma were significant risk factors, with odds ratios of 2.57 and 9.26, respectively. CONCLUSIONS: The prevalence of elbow OA was 55.0%; the prevalence of symptomatic elbow OA was 22.6%; and the risk factors for elbow OA were older age, male sex, and a history of elbow trauma.

Heparin-Induced Thrombocytopenia After Revascularization of Gustilo-Anderson Type IIIC Open Lower Leg Fracture: A Case Report of Subsequent Ischemic Limb Salvage Failure.

BACKGROUND Heparin-induced thrombocytopenia (HIT) is a disease in which the immune response elicited by heparin results in a state of hypercoagulability and platelet activation, leading to thrombocytopenia and thromboembolism. Gustilo-Anderson type IIIC open fractures of the extremities are defined as open fractures presenting with arterial injuries that require repair and result in treatment challenges and complications. The diagnosis of HIT can be difficult in patients with severe trauma with consumptive thrombocytopenia associated with heavy bleeding and the use of heparin after vascular anastomosis. CASE REPORT A 48-year-old man was injured in a car accident, pinching his right lower leg and sustaining a Gustilo-Anderson type IIIc open fracture, for which he underwent emergency revascularization surgery. Heparin was administered continuously immediately after the surgery. On postoperative day 9, ischemic changes were observed in the right foot, and we performed suture re-anastomosis; however, the blood circulation in the right lower leg did not resume, and right lower leg amputation was performed due to ischemic necrosis with the onset of HIT. Postoperatively, the patient was switched to edoxaban after the recovery of his platelet count. Thereafter, the patient experienced no new thrombus occlusion or wound trouble, and was able to walk on a prosthetic leg and return to daily life. CONCLUSIONS It is important to consider the possibility of HIT as soon as thrombocytopenia appears in patients with Gustilo-Anderson type IIIC open fracture who are receiving heparin after vascular anastomosis, as a delayed diagnosis of HIT can make it difficult to save the limb.

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.

A case of solitary digital glomus tumor associated with neurofibromatosis type 1.

An association between glomus tumor and neurofibromatosis type 1 has been reported. It is characterized by multiple tumors and young age at onset. The early diagnosis of neurofibromatosis type 1 is important because it is associated with a high rate of malignancy. A 25-year-old man presented to our hospital with left index finger pain that had persisted for 6 years. Physical and imaging findings suggested a benign soft-tissue tumor. Surgery was performed, and the tumor was pathologically diagnosed as glomus tumor. In this case, the patient with a young-onset glomus tumor was suspected of having neurofibromatosis type 1. An additional medical examination led to the diagnosis of unrecognized neurofibromatosis type 1. We experienced a case in which the onset of a glomus tumor led to the diagnosis of neurofibromatosis type 1. Comorbid neurofibromatosis type 1 should be kept in mind when glomus tumors are diagnosed.

Total elbow arthroplasty for hemophilic osteoproliferative elbow arthritis with severe flexion contracture: A case report.

Total elbow arthroplasty is effective for pain relief and the functional improvement of severe symptomatic hemophilic osteoproliferative arthropathy. Nevertheless, high complication rates have been reported. This report describes clinical results obtained at 30-month follow-up of total elbow arthroplasty in a hemophilic patient with severe flexion contracture. A 50-year-old patient with advanced left elbow hemophilic arthropathy underwent unlinked total elbow arthroplasty. He had sustained an intraoperative fracture of the medial part of a supracondylar humerus complication. To control perioperative bleeding, strict factor VIII replacement therapy was performed under the guidance of hematologists. The total elbow range of motion was 35° preoperatively, but it had improved to 110° postoperatively. The Patient-Rated Elbow Evaluation Japanese version score, which was 53.7 preoperatively, improved to 10.7 postoperatively. During the 30 months after operation, no complication occurred. Good clinical results have been obtained under close collaboration with hematologists and close patient adherence following treatment.

Relationship Between Morphological Change of Median Nerve and Clinical Outcome Before and After Open Carpal Tunnel Release: Ultrasonographic 1-Year Follow-up After Operation.

Background: The aims of this study were 2-fold: (1) to assess the morphological change of the median nerve in patients with carpal tunnel syndrome (CTS) preoperatively and at 6 and 12 months postoperatively; and (2) to analyze correlation between the changes in ultrasonographic findings and the changes in clinical findings after surgical decompression. Methods: Of the 28 patients with CTS, 34 wrists were treated with open carpal tunnel release. We evaluated them using the Boston questionnaire, Japanese Society for Surgery of the Hand Version of the Quick Disability of the Arm, Shoulder, and Hand questionnaire, nerve conduction study (NCS), and ultrasound preoperatively and at 6 and 12 months postoperatively. We measured the cross-sectional area (CSA) of the median nerve at the level of the proximal inlet of the carpal tunnel (CSAc) and more proximally at the level of the distal radioulnar joint (CSAd). Paired t tests and repeated measures analysis of variance of ranks were used to identify changes over time. The Spearman correlation coefficient by rank test was used for the analysis of the relation between the amount of change of CSA and the patient-rated questionnaire score and NCS findings. Results: Findings for CSAc, CSAd, and NCS and patient-rated outcomes at 6 and 12 months postoperatively were significantly lower than their preoperative values. However, no significant correlation was found between the postoperative changes in CSAc, CSAd, and clinical variables obtained preoperatively and postoperatively. Conclusions: Evaluation of sonographic imaging might not be helpful for assessing clinical conditions in patients with CTS after surgical decompression.

Closed rupture of a flexor profundus tendon to the little finger caused by asymptomatic pisotriquetral osteoarthritis: A case required differentiation from the tendon rupture due to hamate bony irregularity by bone erosion.

Carpal joint osteoarthritis and the formation of bony irregularities of the carpal bone cause closed flexor tendon ruptures. This report describes a case of a flexor profundus tendon closed rupture of the little finger due to asymptomatic pisotriquetral osteoarthritis in a 73-year-old woman, which required differentiation from tendon rupture due to hamate bony irregularity due to bone erosion. Computed tomography showed cortical bone irregularities of the hamate and the narrowing of the pisotriquetral joint space, and a bony spur on the radial side of the pisiform. Intraoperative findings revealed the capsule of the pisotriquetral joint was torn on the radial side. Pisiform-hamate ligament disruption and the bony spur on the pisiform were found on this side. However, the flexor tendon floor on the hamate was intact. Surgical resection of the pisiform and a free tendon interposition graft for tendon rupture restored the good function of the little finger. Particular attention should be paid in making the diagnosis in cases with multiple possible triggers for closed flexor tendon rupture.

Proliferative flexor tenosynovitis in the index finger of a 10-year-old baseball player gloved hand: A case report.

Flexor tenosynovitis is rare in young children. This case report describes that of a 10-year-old boy with diffuse swelling of the left index finger, pain when catching a ball, and progressive inability for full flexing of the finger 2 months after starting baseball play. Magnetic resonance imaging showed a defined lesion with iso-signal intensity to muscle on T1-weighted imaging, and with high signal intensity to muscle on T2-weighted imaging. It was enhanced in T1-weighted fat suppression imaging with gadolinium enhancement. Surgical excision relieved the symptom. Histopathological findings mainly indicated proliferation of synoviocytes and plasma cell and lymphocyte infiltration. We speculated that the physical impact of the ball on the left index finger of his gloved hand during catching activated some immunological mechanism and thereby caused nonspecific tenosynovitis in this young baseball player. Awareness of this pathophysiology might raise confidence in proper diagnosis for assessing the swelling of fingers in young baseball players.

Players' satisfaction with daily pitching performance could predict shoulder and elbow injuries in high-school baseball pitchers: a prospective time-to-event study.

HYPOTHESIS AND BACKGROUND: The relationship between baseball pitchers' satisfaction with their performance and the incidence of shoulder and elbow injuries is unclear. We hypothesized that self-evaluated satisfaction with pitching performance before an injury and incidence of shoulder and elbow injuries are related. METHODS: Baseline data on baseball experience, height, weight, elbow and shoulder range of motion, and shoulder muscle strength of high-school baseball pitchers were collected. During the season, all participants completed a self-recorded questionnaire regarding satisfaction scores, presence of shoulder and/or elbow pain, and pitching limitations due to shoulder and/or elbow pain experienced daily to determine when injuries occurred and record the satisfaction scores. The optimal satisfaction score cutoff value was determined through receiver operating characteristic curve analysis; participants were categorized into satisfied and unsatisfied groups. Statistical tests were performed to evaluate the differences between the groups, obtain the time-to-event curves, and calculate the hazard ratios for the incidence of injury. RESULTS: Overall, 108 participants aged 15-17 years were enrolled and divided into satisfied (88) and unsatisfied (20) groups. The injury incidence rate was 10.2% and 50.0% in the satisfied and unsatisfied groups, respectively. High-school baseball pitchers with low satisfaction had a significantly increased risk of shoulder and elbow injuries; these players had a 7.3-times greater risk of injuries and 1.9-times earlier occurrence of injuries than pitchers who were satisfied with their performance. CONCLUSION: Daily evaluation of players' self-satisfaction could predict shoulder and elbow injuries in high-school baseball pitchers.

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.

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.

Reverse wedge osteotomy for Madelung's deformity in a high school student: A case report.

Madelung deformity is a congenital disorder with the malformation of anterior ulnar bowing of radius and a dorsally protruding ulnar head caused by premature growth disturbance at the medial volar aspect of the distal radius. This report describes a bilateral idiopathic Madelung deformity in a 17-year-old woman treated successfully using reverse wedge osteotomy of the distal radius in a symptomatic left wrist. Reverse wedge osteotomy can orient the radial joint surface while correcting the whole radius length by reversely putting the wedge bone removed from the distal metaphysis of radius, the base of which is cut from the surplus of the radial and dorsal cortical bone in the hypotrophic portion. We corrected the palmar subluxation of the carpus, restored her good function, and relieved her wrist pain.

Collagenase Clostridium histolyticum Injection Therapy Improves Health-related Quality of Life in Patients with Dupuytren's Disease.

OBJECTIVES: This study was conducted to investigate the changes in clinical and psychosocial outcomes in patients with Dupuytren's disease after initial treatment with collagenase Clostridium histolyticum (CCH) injection. METHODS: This study involved 14 patients with Dupuytren's disease who underwent treatment with CCH injection. The range of motion of each phalangeal joint was measured before treatment and at 6 months posttreatment. The following assessments were also carried out pre- and posttreatment: the Geriatric Depression Scale Short - Japanese version (GDS-J) to evaluate depressive status, Hand 10 to assess hand health status, and EuroQol-5-dimension-3-level Japanese version to evaluate health-related quality of life. RESULTS: Significant improvements were found in metacarpophalangeal joint extension and proximal interphalangeal joint extension. Significant differences were also found between values before the initiation of CCH injection and those at 6 months posttreatment for the EuroQol index score and the EuroQol Visual Analog Scale (VAS). Significant positive correlations were found between the pre- to posttreatment change in GDS-J scores and for the change in Hand 10 scores. Moreover, a significant negative correlation was found between the change in GDS-J scores and change in EuroQol index scores/EuroQol VAS scores before and at 6 months after CCH injection. CONCLUSIONS: For patients with Dupuytren's disease, CCH therapy directly improved the health-related quality of life. The degree of improvement of depressive status was associated with the degree of improvement of hand health status and health-related quality of life.

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.

Successful Nonoperative Treatment of Osteochondritis Dissecans of the Humeral Capitellum in a Young Baseball Player with Advanced Skeletal Maturity.

BACKGROUND: Osteochondritis dissecans (OCD) of the humeral capitellum presents most typically in adolescent athletes who perform repetitive overhead activities. Earlier studies have demonstrated that conservative treatment of OCD is appropriate for patients with an open capitellar growth plate from the standpoint that spontaneous healing can be expected. CASE: A 12-year-old male baseball player with two years of experience with a local team participated in our medical check that included screening for capitellar OCD using ultrasonography. The subject experienced elbow pain when throwing, and ultrasonographic elbow examination indicated OCD of the capitellum, detected as irregularity of the subchondral bone of the capitellum. The initial radiograph, taken with the elbow at 45° of flexion, identified new bone formation in the lateral aspect of the OCD lesion; however the epiphyseal lines of the capitellum and lateral epicondyle were closed. We advised the patient to stop heavy use of the elbow, e.g., throwing and batting, and started conservative treatment in anticipation of spontaneous healing. Physiotherapy focusing on the shoulder girdle, core, and hip and lower limb stretches were performed to resolve general tightness. The OCD lesion had healed completely 12 months after the start of conservative treatment. DISCUSSION: Conservative treatment for young baseball players might be worth considering if lateral new bone formation within the OCD lesion is detected on radiographic findings, even if the epiphyseal lines of the capitellum and lateral epicondyle are closed.

The ultrasonographic assessment of the morphologic changes in the ulnar nerve at the cubital tunnel in Japanese volunteers: relationship between dynamic ulnar nerve instability and clinical symptoms.

BACKGROUND: We investigated the differences in the prevalence of ulnar nerve instability (UNI) by hand dominance and evaluated the relationship between UNI and morphologic changes in the ulnar nerve and the clinical findings and upper limb function. METHODS: This study examined 153 healthy participants (n = 306 elbows; 44 men, 112 women; mean age 65.4 years) who underwent ultrasonography to assess the ulnar nerve cross-sectional area (UNCSA) at three points of the bilateral cubital tunnel at 30° of elbow flexion. Participants were divided into three groups based on the ultrasonography findings of UNI: no instability (type N), subluxation (type S), and dislocation (type D). For the dominant and nondominant sides, we assessed the relationship between the UNCSA and clinical factors, including the age, gender, height, weight, body mass index, fat mass, grip strength, key pinch strength, UNCSA, and Patient-Rated Elbow Evaluation score. RESULTS: We identified 75 cases without instability in both elbows and 78 cases with some instability. The prevalence of UNI was 51%. No significant difference was found between hand dominance and the prevalence of UNI. The UNCSA at 1 cm proximal to the medial epicondyle on the bilateral sides in type S was the most increased among three types. CONCLUSION: UNI was identified in almost half of the participants, with no marked difference found in the hand dominance. The UNCSA at 1 cm proximal to the medial epicondyle was significantly increased the most in type S. UNI does not appear to be associated with elbow symptoms in the general population.

High baseball loads induce shoulder and elbow injuries among high school baseball pitchers: a prospective study.

Studies on the relationship between baseball loads (practice, training, and competition hours) and shoulder and elbow injuries among high school pitchers are limited. Therefore, this study included 92 male high school baseball pitchers and evaluated their preseason shoulder and elbow conditions. All participants completed a self-recorded questionnaire regarding baseball load, presence of shoulder pain or elbow pain, or both, and pitching limitations due to shoulder and/or elbow pain experienced daily to determine the occurrence of injuries and record the baseball load. The optimal load cutoff value was determined using a receiver operating characteristic curve analysis. Participants were categorized into high-load and low-load groups according to the aforementioned cutoff value. The Kaplan-Meier method was used to obtain time-to-event curves, and cox proportional hazards models were used to calculate the hazard ratios for injury rates. The cutoff value of the average baseball load was 324.4 min per day. A high load (> 5.5 h/day) led to a 2.6-times greater risk of injuries and 3.3-times earlier occurrence of injuries than a low load (< 5.5 h/day). Therefore, a high load is a risk factor for shoulder and elbow injuries in high school baseball pitchers.

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.