〔Abstract〕This study aimed to clarify the concussion-reporting behavior of American football players in the Kanto Collegiate Football Association Division 1 league when they suffered a sports-related concussions (SRCs) and its effects on their return to play. SRCs for 5 seasons were analyzed, which recorded with injury mechanisms, symptoms and SCAT5 scores by our team physicians. The study examined factors such as university year, history of previous concussions, reporting timing, and return days. A two-way ANOVA was used to compare the number of return days based on reporting behavior. The results showed that 41 out of 133 participants with SRC (30.8%) continued playing without reporting concussions. Significant differences were observed in the number of days to noncontact and full return depending on the reporting and concussion history (F1,70 = 7.342, p = 0.08；F1,70 = 4.068, p = 0.048；F1,70 = 6.416, p = 0.014). Immediate reporting and post-SRC play cessation are crucial for an early return to competition.

Athletes often suffer from hamstring injuries, particularly proximal hamstring tendon avulsions, which typically require surgical intervention due to their performance-impairing effects. Here, we present three cases of surgical treatment for proximal hamstring tendon avulsions in contact sports athletes. The patients, two rugby players and one wrestler, sustained injuries during hip flexion and knee extension, classified as JISS type III-3. Surgical repairs were performed using anchors within 5 to 17 days post-injury. Following surgery, the patients underwent a rehabilitation program, following a 3-week period of hip flexion restriction using a hip spica brace. All three patients achieved a recovery of over 90% of muscle strength, compared to their uninjured side, and were able to return to competition within 5 to 9 months. Early surgical intervention following diagnosis is crucial for returning to sports. Postoperative rehabilitation, including the return to sports, should be advanced in stages, guided by the condition of the repaired site observed on MRI images, muscle strength evaluations and improvement in subjective symptoms.

This study aimed to survey on “any complaints” among volleyball players. A web-based survey was sent to 301 female university volleyball players. The questionnaire included basic information such as age, height, weight, and body mass index; athletic information such as years of experience, frequency, and duration of practice; and injury-related information such as the presence of any complaints, injury location and mechanism, subsequent participation in athletics, degree and duration of pain during athletics, and the impact of pain on performance. Of the 301 survey recipients, 112 players (37.2%) provided valid responses, among whom 44 players (39.3%) had any complaints (total, 59 cases). The highest incidence of any complaints was observed in the lumbar region (15 cases [25.4%]). Of the 59 cases, athletic participation continued in 57 (96.6%). The mean numerical rating scale score was 4.3±1.4 (range, 2.9-5.7), indicating relatively low to moderate pain severity. The presence of any complaints reduced the players’ performance by approximately 30%. To maintain performance and prevent injuries among volleyball players, it is necessary to pay attention not only to injuries that may limit their participation, but also to any complaints they have.

The purpose of this study was to compare the length of the humerus on the dominant and nondominant sides of male college baseball players. The study included 37 male college baseball players and 71 swimmers. Whole-body scans were performed using DXA, and the length of the humerus on both sides was measured from the obtained images. To compare the humerus lengths of the dominant and non-dominant sides between the baseball and swimming groups, a two-way analysis of variance was performed. A significant difference was observed between the dominant and non-dominant sides of the humerus length in the baseball and swimming groups (p = 0.047). The length of the humerus in the baseball group was significantly lower than that in the swimming group, both on the dominant and non-dominant sides (p ＜ 0.001). In comparing the dominant and nondominant sides, the humerus length on the non-dominant side in the baseball group was significantly greater than that on the dominant side (p = 0.004). The characteristics of the sport, which requires frequent use of the dominant-side humerus, suggest that the humerus on the dominant side may have significantly shortened more than that on the non-dominant side.

This study identified factors associated with musculoskeletal injury sites in competitive swimmers. The causes of injuries unrelated to swimming motions are often unclear; therefore, distinguishing between swimming motion-related and non-swimming motion-related injury factors is critical. Data on competitive levels, injury factors, and injury sites were collected from competitive swimmers visiting a medical institution. Chi-square (χ2) tests were performed using cross-tabulation. The odds ratios (ORs) were calculated using a multinomial logistic regression model, with injury sites as the dependent variable and sex, age, competitive level, and injury factors as independent variables. The χ2 tests and residual analyses revealed that swimming motion-related lower limb disorders were significantly less frequent, whereas trunk disorders were more frequent. Conversely, non-swimming motion-related lower limb disorders were significantly more frequent, whereas trunk disorders were less frequent. The swimming motion-related OR for lower limb disorders was 0.2. These findings suggest that prolonged, intensive training may cause swimming motion-related trunk disorders in competitive swimmers. Moreover, the lower risk of lower limb disorders caused by swimming motions highlights the need for preventive measures for such disorders beyond competitive swimming contexts.

(Purpose) To investigate the relationship between knee joint sports injuries during growth period, and sense of knee joint position and physical functions in junior athletes during growth. (Methods) Thirty-six junior athletes (18 males and 18 females; mean age: 11.1±1.9 years) in the growth phase were divided, based on medical check-ups, into an injury group (IG, n=11; defined as Osgood-Schlatter disease or jumper’s knee) and a non-injury group (NIG, n=25). The sense of knee joint position was assessed using markerless motion capture, in which participants reproduced a 120̊ knee flexion angle three times under weight-bearing conditions, and the angle error was calculated. Physical functions including grip strength, flexibility, jumping ability, and agility were measured. Unpaired t-tests were used to compare body size, sense of knee joint position, and physical functions between the groups. (Results) The IG had significantly higher height, grip strength, and angle error than NIG (all p＜0.05). (Conclusion) Assessment of sense of knee joint position may be more effective than physical functions as an indicator for the prevention and detection of knee injuries in junior athletes during growth.

(Objective) Investigate fresh lumbar spondylolysis using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ). (Methods) The subjects were 45 patients with early lumbar spondylolysis with a single vertebral body onset, who were diagnosed with fresh lumbar spondylolysis by MRI from November 2021 to May 2023. The items examined were the severity scores of the five areas of JOABPEQ pain-related disorder, lumbar functional disorder, walking functional disorder, social life disorder, and psychological disorder, and the low back pain VAS. All cases were examined, as well as two groups of unilateral and bilateral cases. Statistical analysis was performed using the Mann-Whitney U test and Student’s T test, with a significance level of 5%. (Results) In the severity scores of the areas in all cases, the walking functional disorder area was high. No significant differences were found between the unilateral- and bilateral subgroups in any domain, questionnaire item, or VAS score. (Conclusion) In fresh lumbar spondylolysis cases, the severity scores of the walking functional disorder area were high, and patients were hardly aware of walking functional disorder. No significant difference was noted in JOABPEQ or VAS scores between patients with unilateral versus bilateral spondylolysis.

The purpose of this study was to compare the differences of the dominant and non-dominant humerus length and forearm length in collegiate tennis, baseball, and throwing events in track and field athlete. The subjects were male university athletes who played tennis (n=30), Baseball (n=37), and throw (n=45), and were measured using a DXA in whole body mode. The symmetry index was used to calculate the dominantnondominant difference (%) between the humerus length and forearm length, and a one-way ANOVA was used for statistics. There was a significant difference in dominant-nondominant difference in humerus and forearm length (F=19.9, p＜0.001; F=5.6, p=0.005), and tennis was significantly higher than throw and Baseball (p＜0.05). Mechanical loading of the upper limb by tennis may influence the increase in bone length.

(Purpose) To identify the injury characteristics of senior football players who visited an orthopedic clinic. (Methods) Male senior football players ≥ 40 years old who visited a single orthopedic clinic between September 2020 and September 2023 were included. Based on medical records, we investigated injury location, type, pattern (trauma or overuse), and diagnosis and analyzed these characteristics by age. (Results) Eighty-seven patients (mean age 55.1±11.0 years) with 143 diagnoses were analyzed; the most common injury location was the knee (47 cases), followed by the lower leg/Achilles tendon (26 cases) and the thigh (15 cases). In terms of injury pattern, trauma was more common than overuse in patients ＜/≤ 50 years old; however, overuse injuries were more common than trauma in patients ＞/≥ 50 years old. Among those with knee injuries, osteoarthritis diagnoses were more common in players ＞/≥ 50 years old than in those ＜/≤ 50 years old. Hamstring and gastrocnemius muscle injuries were equally common in younger and older players. (Discussion) Senior football players who visited an orthopedic clinic were most likely to have knee symptoms. Trauma-induced injuries were more common in younger players, while overuse injuries and knee osteoarthritis were more common in older players.

Thoracic elevation mobility and the scapular upward rotation (SUR) angle are essential for preventing shoulder disorders in rugby players. However, changes in thoracic elevation mobility and SUR angle over time in college rugby players are unknown. This research aimed to explore changes in the thoracic elevation mobility and SUR angle over time. The participants were healthy university rugby players who underwent medical checkups between 2016 and 2022. Thoracic mobility was assessed by measuring the upper thoracic motion using frontal radiographs in both the drooped and maximally raised positions of the upper limbs. The SUR angle was measured on both the dominant and nondominant sides using a 45̊ scapular plane elevation image. Each parameter was compared using a two-way repeated-measures analysis of variance, with two factors: grade (first and second year of university) and position (forward and backs). Of the 138 rugby players who underwent medical checkups at our university, 67 were included in the analysis. The SUR angle on the non-dominant side of backs players was lower in the second year compared to the first year. These findings suggest that the SUR angle may decrease as players progress through their college rugby years, particularly in backs.

Judo is a school sport associated with several fatal accidents in the past. A relationship between severe head injury and sports-related concussion (SRC) has been pointed out, and the response to SRC is important. Herein, we examined the response of junior high school judo instructors to SRC. An SRC seminar was organized for these instructors, followed by a questionnaire survey. The questionnaire included eight items regarding the knowledge of SRC, response after injury, and changes after attending the seminar. The instructors were divided into the young (＜10 years of experience) and experienced (＞10 years) groups, following which the results were examined. The results revealed that the experienced group had more knowledge about SRC, and the injured students’ return to the competition on the day of the injury was unaffected. However, injured students under the instructors of the young group had more frequent medical visits before returning to the competition. Changes were observed after the seminar, indicating its usefulness. Although many instructors were safety-conscious regarding same-day return and pre-return medical visits, all were not completely capable of taking safety measures. The seminar was considered effective and could help raise awareness about concussions.

A rupture of the adductor longus tendon represents a relatively uncommon injury, and its treatment remains controversial. We present a case of adductor longus tendon rupture successfully managed with conservative therapy in a 20-year-old male collegiate soccer player. The injury occurred while he was shooting with his right foot, resulting in difficulty walking. MRI revealed an avulsion of the adductor longus tendon from the pubic bone, confirming the diagnosis of adductor longus tendon rupture (JISS classification type 3/grade 3). We opted for conservative management, imposing restrictions on hip adduction and abduction of up to 10̊ for the initial 3 weeks post-injury. A follow-up MRI at 10 weeks showed only residual high-signal changes at the origin of the adductor longus, and the patient was able to fully return to practice. There was no recurrence of the injury noted at the 12-month follow-up. Given the presence of other muscles contributing to hip adduction, such as the adductor magnus, surgical anatomic repair may not be imperative, and conservative therapy demonstrated success in this trauma.

We present a case of injury isolated to the posterolateral corner (PLC) of the knee caused by climbing. A 28-year-old male, sustained a right knee injury during a heel hook motion and was diagnosed with PLC injury (Hughston classification grade II). Initial evaluation revealed tenderness of the popliteus muscle and weakness in gluteus, popliteus, and hamstring muscles on the affected side. The knee varus stress test revealed only pain. The dial test (knee flexion at 30̊) was positive (10̊ difference between affected and unaffected sides). The patient was fitted with a knee brace for 6 weeks and offered rehabilitation. The patient returned to competition 12 weeks after injury. In the final evaluation, the tenderness in the popliteus muscle had disappeared, gluteus, popliteus, and hamstring muscle strength had improved, and the dial test was negative. We conclude that Hughston classification grade II injuries isolated to the posterolateral corner of the knee can be treated conservatively, and that it is important rehabilitation that takes into account the competitive characteristics at an early post-injury stage.

The total energy expenditure (TEE) of 10 male collegiate sprinters (age: 20.5±1.2 years, height: 177.6 ±4.6 cm, weight: 68.4±7.1 kg) was measured during the winter off-season training period using the doubly labeled water method. TEE averaged 3149±337 kcal/day or 50.1±3.6 kcal/fat free mas (FFM) kg/day. Resting metabolic rate (RMR), assessed by indirect calorimetry, was 1858±243 kcal/day or 29.6±3.1 kcal/FFM kg/day. Physical activity level (PAL), calculated from TEE and RMR, was 1.71±0.16, aligning closely with the off-season standard of 1.75 for athletes in power-based sports, as recommended by Dietary Reference Intakes for Japanese athletes. Notably, TEE and PAL showed considerable variation among individuals within the team, underscoring the importance of personalized assessment when evaluating the energy requirements of each athlete.