The mechanisms of anterior cruciate ligament (ACL) injury while skiing and methods to prevent it have recently been elucidated. However, the rate of ACL injuries has not changed much over the past 10 years,remaining at approximately 10%.

A total of 1,429 skiers responded to this questionnaire survey. Two hundred sixty-six skiers (14.4%) answered that they had undergone ACL reconstruction after a ski injury. It was found that 71.3% of skiers experienced injury once on one side, 17% on both sides and 7.3% twice on the same side. The self-recognized posture at the time of the ski injury was backward bending and the slip-catch mechanism in approximately 20%. Concerning the most common perceived injury in skiers the response was ACL injury in 90%, MCL injury in approximately 50% and shoulder dislocation or fracture in approximately 30%. Significantly more skiers who had experienced ACL injury than those who had not (non-injured skiers) answered that (i) ACL injury can be prevented, (ii) stretching, trunk exercises, and knee-strength and balance exercises serve as preparatory exercises before skiing, and (iii) the hamstrings and trunk are important exercise areas.

The purpose of this study was to determine the accuracy of lumbosacral angle using MRI and an in clinometer, and to examine predictive regression of these two methods. Seventy adolescent boys experienced MR imaging of the lumbar region and lumbosacral alignment measurement using an inclinometer. Sacral slope was calculated as the angle between the top of the sacrum and the horizontal line. The lumbosacral angle was defined as the angle between the lumbosacral joint and the horizontal axis. Statistical analysis was performed using linear regression analysis to determine whether sacral slope can be predicted by the lumbosacral angle, and Bland Altman method was used to evaluate the agreement between the two measurement methods. The fixed error cal culated as the difference between the sacral slope by MRI and the lumbosacral angle by inclinometer was 10.06±3.29̊(95%CI: 9.27-10.84), with small proportional and random errors. The regression equation was y=0.85x＋13.49. Although the results of this study indicated that the inclinometer underestimated the lumbosacral angle, if fixed error is taken into account, the measurement by inclinometer may be useful in predicting the lumbosacral angle in adolescent athletes.

(Purpose) The aim of this study was to examine the factors involved and status of return to sports after Achilles tendon repair.

(Subjects and Methods) The subjects were 118 patients (mean age 39.6±12.2 years) who underwent unilateral Achilles tendon repair for the first time between 2017 and 2019. Subjects had participated in regular sports activities before the surgery. Post-surgery follow-up was possible for up to 9 months. Besides age and body mass index (BMI), various factors like post-operative single-leg heel-rise height index (HRHI), Achilles tendon resting angle (ATRA), the ratio of the presence or absence of pain in each group and the start time of obtaining movement (Movement) were examined. The factors affecting return to sports were examined by multiple logistic regression analysis, and their cutoff values were obtained.

(Results) The results showed that the return to sports rate was 79.7%. Other items than age, including Movement, all showed significant differences between the two groups. Factors that affected return to sport were BMI and HRHI. For BMI, the odds ratio was 0.85 and the cutoff value was 24.5 kg/m². For HRHI, the odds ratio was 1.05,and the cutoff value was 86.7%.

(Conclusion) The ratio of return to sports after Achilles tendon repair at our hospital was approximately 80%,which is a good result. To return to sports it is necessary to have adequate HRHI and to perform rehabilitation in consideration of BMI, pain generation, and ATRA.

The purpose of this study was to examine the relative growth of muscle thickness in the lateral ab dominal muscle groups of junior high school students as well as the differences in growth patterns between the three individual muscles. The subjects were 191 junior high school students from a local club team and the right external oblique; EO, internal oblique; IO and transversus abdominis; TrA muscle thicknesses were measured us ing an ultrasound imaging device. The height and these parameters were plotted on a logarithmic graph to obtain the allometric equation y = bx ^a . EO and IO were represented by three-phase straight lines with two inflection points, EOʼs allometry coefficients being 2.58, 1.56, and 2.76, and the inflection points being 142.0 cm and 171.3 cm. IOʼs allometry coefficients were 0.82, 2.05, and 4.55, and its inflection points were 157.4 cm and 170.4 cm. TrA was depicted as two-phase straight lines with allometry coefficients of ­1.53 and 1.56, with the inflection point of 145.3 cm. This suggests that TrA which has a stabilizing effect on the trunk, grows early.

The effect of hip abduction stretching on the flexibility of the hip adductor muscles is unclear, al though hip abduction stretching has been reported to improve hip abduction angle. This study aimed to investigate the effect of static hip abduction stretching on the flexibility of the hip adductor muscles. Twelve men were recruited. Static abduction stretching was performed for 1 min × 5 sets at maximum hip abduction, 0̊hip flexion and 90̊knee flexion. The shear modulus of the adductor longus, adductor magnus, and gracilis was measured us ing shear wave elastography. The shear modulus of each muscle was measured from 0 to 40̊hip abduction angle in 10̊increments before and after stretching, respectively. The maximum hip abduction angle after stretching was significantly higher than that before stretching. Only the shear modulus of the adductor longus significantly decreased at 30̊and 40̊hip abduction after stretching. No interaction and main effect of time were noted for the shear modulus of the adductor magnus and gracilis. These results indicated that hip abduction stretching in creased the maximum hip abduction angle and improved the flexibility of the adductor longus, while not improv ing the flexibility of the adductor magnus and gracilis.

The purpose of this study was to examine the relationship between the amount of change in medial longitudinal arch height of the foot (MLA) on static weight bearing and the amount of change in knee flexion angle during single-leg landing. The subjects were 22 healthy adults comprising 11 males and 11 females. In evaluation of the foot alignment, distance from the floor to the most prominent part of the navicular tuberosity was measured in the sitting and standing positions, and the difference in the distance between the two positions was defined as amount of change in MLA. In the kinematic analysis of landing, markers were attached to the bony landmarks in the lower limbs, single-leg landing from a 30-cm-high platform. And then, knee flexion angle was measured on the video image. The analysis of the obtained results showed a significant negative correlation between the amount of change in MLA and change in knee flexion angle during single-leg landing. Although there have been studies reporting the effect of MLA on knee valgus angle during landing, the results of this study suggest that MLA also relates to the amount of change in the knee flexion angle in landing.

This study aimed to investigate changes in psychological reactions and knee pain 3 months after re turn to sports (RTS) following anterior cruciate ligament (ACL) reconstruction surgery, and to determine whether there were changes in psychological reactions and residual fear and knee pain upon RTS. Twenty-three patients underwent initial unilateral ACL reconstruction, returned to sports at the same level and in the same sport as be fore surgery, and were available for investigation until 3 months after RTS. The survey items were activity level,sports, satisfaction, Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale, knee pain, and fear at the time of RTS and 3 months after RTS. Both satisfaction and ACL-RSI score were significantly higher (p＜ 0.001), and fear was significantly lower (p＜0.05) at 3 months after RTS, but there was no significant difference in knee pain. The improvement in ACL-RSI score was attributed to increased satisfaction, decreased fear of reinjury,increased confidence in playing sports, and decreased fear. However, some patients still had residual scary motion and knee pain. Therefore, it is necessary to continue instruction in the correct use of the body to overcome fearful movements and ongoing follow-up for knee pain after RTS.

The purpose of this study to investigate the incidence and the location of injuries in throwing ath letes. Collegiate and professional throwing athletes were given a questionnaire pertaining to their injury histories. In throwing athletes, the most common injury location was the lower back, with the exception of javelin throwers,who had the most injuries to the elbow joint. Low back injuries were the most common in throwing athletes, and elbow joint injuries were significantly more common in javelin throwers than in other throwers.

In this study, we investigated the characteristics of secondary anterior cruciate ligament (ACL) in jury (reinjury or contralateral injury) in female gymnasts who underwent ACL reconstruction (ACLR). We investi gated the secondary ACL injury rate, age at secondary ACL injury, time to secondary ACL injury, and the event and injury mechanism at the time of initial and secondary ACL injury in 37 female gymnasts who returned to gymnastics after ACLR. The reinjury and contralateral injury rates were 8.1% (3 patients) and 10.8% (4 patients),respectively, and the rate of secondary ACL injury was 18.9% (7 patients). The mean time to secondary ACL in jury was 2 years and 11 months. Six of seven patients were reinjured during participation in an event different from the one that led to the previous injury. Six of seven patients were reinjured by the same landing as the one associated with the previous injury; one patient was reinjured after accidentally falling off the uneven bars. Educa tion and creation of awareness regarding the risk of reinjury associated with landing in all events is important in gymnasts who return to competitive sport, to prevent secondary ACL injuries.

The Tokyo 2020 Olympic and Paralympic Games had been postponed for a year duetothe spread of the new coronavirus disease 2019 (COVID-19). Since the infection of athletes may spread COVID-19 all over the world, the medical care system focused on infection control in addition to regular medical care. This study reports on the implementation of ophthalmic medical services at the AthletesʼVillage General Clinic (hereinafter referred to as “Polyclinic”) for the Tokyo 2020 Olympic and Paralympic Games.

There were 697 patients during the Olympic Games, and 556 patients during the Paralympic Games. Visual acuity of patients at the Olympic and Paralympic Games was as follows: At the Olympic Games,1/620 (0.2％) had a visual acuity of log MAR 1.0 (Snellen equivalent, 20/200) or worse; at the Paralympic Games the respective number of patients was 31/516 (6.0％).

During the Olympic Games, there were seven patients who received treatment due to trauma. From the results of the questionnaire survey of volunteers who worked in Polyclinics, a handy slit and high/low power eye glass lenses were necessary.

At the Tokyo 2020 Olympic and Paralympic Games, the eye care team ―consisting of ophthalmologists, certified orthoptists, and opticians ―were able to provide ophthalmic care efficiently amidst the COVID-19 pandemic.

We report a rare case of proximal tibiofibular instability treated using TightRope. An 18-year-old male, soccer player, hit his right knee on the ground with the knee in a flexed position during a game. He was diagnosed with a partial PCL injury by his previous doctor and received a conservative treatment. However, he suffered from right knee pain for 3 months after the injury. The Sijbradij test and proximal tibiofibular joint stress Xrays showed a right-side instability, and we diagnosed the patient with proximal tibiofibular joint instability. We performed proximal tibiofibular joint reconstruction using TightRope. The patient could run 2 months postoperatively and returned to the game 6 months postoperatively. Proximal tibiofibular joint instability is rare, and diagnostic criteria and treatment have not been established. Previous reports have suggested that it is associated with radiating pain of the common peroneal nerve and general joint laxity. Joint fixation using metal screws is associated with the risk of screw breakage owing to weight bearing, which necessitates peroneal osteotomy and metal removal. Proximal tibiofibular reconstruction using TightRope is a minimally invasive and effective technique that enables micro-motion, and is similar to physiologic ligament reconstruction. TightRope doesnʼt require peroneal osteotomy or metal removal.

We investigated the recovery status of 24 legs of 20 classical ballet dancers who underwent open procedures for os trigonum between 2016 and 2022. The average amount of time during which participants did only center practice 5.5 weeks (range, 3-10), and the average amount of time full return was 10 weeks (range4-24), and 22 out of 24 legs (92%) recovered fully within 12 weeks. Seventeen patients returned to dance without any complaint, 3 had residual symptoms that did not affect their dancing, and 100% returned to dancing. A comparison the literature found that, the recovery period was almost identical to that achieved with endoscopic resection.

(Objective) To examine the status of anemia and iron deficiency in high school female athletes based on the results of medical checkups of designated athletes who excelled in sports in Oita Prefecture.

(Methods) We examined the results of blood tests of 162 high school female athletes, divided into quartiles based on their hemoglobin levels.

(Results) The mean and the median hemoglobin levels were both 12.9 g/dl, which is lower than the average for females in general. Ferritin and transferrin saturation were significantly lower in the first quartile group by hemoglobin volume than in the fourth quartile group. There were no significant differences in the creatinine and total testosterone levels, but the decrease in cholinesterase and increase in the urea nitrogen/creatinine ratio were significant.

(Conclusion) In the general population of female high school students, skeletal muscle does not increase, but in athletes, skeletal muscle increases, suggesting that iron deficiency is caused by the increase in tissue iron contained in skeletal muscle. However, the effect of a low energy intake and iron loss due to menstrual bleeding were considered as the cause of the decrease in hemoglobin.