Objective: With the remarkable advances in diagnostic ultrasound equipment, there is a growing need for ultrasound diagnosis of muscle and soft tissue injuries in sports injuries. Among these, hamstring strains are often difficult to treat and require early and accurate diagnosis. Injuries to the proximal part of the hamstring often take a long time to heal. For this reason, the diagnosis of proximal hamstring injuries is extremely important. The structure of the origin tendon is characteristic, and it is a complex in which the semitendinosus muscle (ST) of the medial hamstring and the long head of the biceps femoris muscle (BFLH) of the lateral hamstring share a conjoint tendon (CT). On the other hand, the semimembranosus muscle (SM) attaches to the ischial tuberosity independently. In this study, we created a classification of injury sites focusing on the origin tendon, and investigated the distribution of injury location, relationship to the player’s position, and the detection rate of ultrasound diagnosis. Material and Methods: We used ultrasound and MRI to diagnose 52 university men’s rugby players who had suffered a hamstring strain for the first time and investigated the distribution of the injured areas. We performed an ultrasound scan as the initial diagnosis and used MRI as a final diagnostic tool. A classification focusing on the origin of the muscle was created. First of all, it was divided into two types: the BFLH-ST complex type, which originates in the CT, and the SM type, which originates in the SM tendon. We also classified BFLH-ST complex damage, including CT damage, as Type I, a BFLH injury without CT injury as Type II, and a ST injury without CT injury as Type III. We then investigated the distribution of the injury location. The degree of ultrasound detection in each injury type was evaluated in three grades. The frequency of BFLH complex and SM injuries was investigated in players who played the forward (FW) and back (BK) positions. Results: The distribution was 40 limbs (77%) for BFLH-ST complex injury type and 12 limbs (23%) for SM injury type. In the BFLH complex type,19 limbs which met the Type I classification criteria for CT tear, 19 limbs met the Type II, and 2 limbs met the Type III. FWs had a higher incidence of SM injuries and BKs had a higher incidence of BFLH-ST complex injuries. With regard to the detection of muscle injuries via ultrasound, a high rate of detection was possible, except for a slight injury to the myofascial junction of the BFLH. Discussion: In terms of the distribution, the BFLH-ST complex, which shares the same origin tendon (i.e. CT), had a higher frequency of muscle tears than the SM. In addition, CT junction injuries occurred frequently in Type II as well as Type I (=CT injury). One possible cause is that the CT is subject to concentrated traction stress from both the medial and lateral hamstrings. With ultrasound, the detection rate of muscle damage around the BFLH-ST complex and SM originating tendon was high, suggesting that it is useful as an initial diagnosis. From this, it can be said that ultrasound is also useful for primary evaluation of “proximal hamstring injury”, which is prone to severe and should be given a final diagnosis using MRI. Conclusions: We created a classification system focusing on the originating tendons and clarified their incidence rates. In this study, ultrasound was found to be useful in the detection of originating tendon injuries. We also identified the characteristic sonographic findings of each type.

Background/Objectives: Proximal hamstring injuries involving the biceps femoris–semitendinosus (BF–ST) conjoint tendon (CT) often exhibit delayed healing, yet the prognostic significance of CT involvement and intratendinous injury morphology has not been fully clarified. This study aimed to determine whether full-layer CT injury, particularly bilateral involvement in Zone C, prolongs return-to-play (RTP) in competitive rugby athletes. Methods: This prospective study evaluated 41 university rugby players with acute BF–ST complex injuries using clinical examination, ultrasonography, and MRI. Injuries were classified by Type (I: full-layer CT; II: BFLH-only; III: ST-only), Zone (A–E), and Grade (0–3). RTP was defined as unrestricted return to team training or match play. Group differences were analyzed using ANOVA or non-parametric tests with appropriate post hoc corrections. Results: Type I injuries required significantly longer RTP (11.4 ± 4.8 weeks) than Type II (5.3 ± 2.4 weeks) and Type III (4.0 ± 1.7 weeks), confirming the strong impact of CT involvement on prognosis. In Zone C, bilateral full-layer CT involvement was associated with an approximately twofold longer RTP duration compared with unilateral BFLH-side injuries, indicating that intratendinous tissue disruption influences recovery. These findings highlight the importance of early MRI-based assessment to identify clinically relevant tendon involvement patterns. Conclusions: Full-layer CT injuries, particularly bilateral intratendinous patterns in Zone C, markedly prolong RTP compared with isolated BFLH or ST injuries. An MRI-based classification incorporating injury type, zone, and extent of CT involvement provides clinically valuable prognostic information and may enhance RTP decision-making.

Background: Proximal hamstring injuries involving the biceps femoris–semitendinosus (BF–ST) conjoint tendon are clinically challenging, yet the prognostic impact of full-layer conjoint tendon (CT) injuries remains unclear. This study aimed to determine whether CT involvement prolongs the time to return to play (RTP) compared with isolated BFLH or ST injuries. Methods: A prospective cohort of 41 university rugby players with acute proximal BF–ST complex injuries was evaluated using standardized physical examination, ultrasonography, and MRI. Injuries were classified by Type (I: full-layer CT; II: BFLH-only; III: ST-only), Zone (A–E), and Grade (0–3). RTP was defined as full participation in team training or competition. RTP differences among Types and, within Type I, across Zones and Grades were analyzed using appropriate parametric or non-parametric tests. Results: Type I injuries required significantly longer RTP (11.4 ± 4.8 weeks) than Type II (5.3 ± 2.4 weeks) or Type III (4.0 ± 1.7 weeks). In Zone C, bilateral involvement of both BFLH and ST resulted in longer RTP than unilateral BFLH injury. Within Type I, Zone A (origin detachment) showed the longest RTP (20 weeks), exceeding Zones B and C. Higher Grades were also associated with prolonged recovery. Conclusions: Full-layer CT injuries represent a distinct clinical entity with markedly delayed RTP compared with isolated BFLH or ST injuries. Classification that distinguishes CT involvement provides useful prognostic information and may enhance RTP planning in athletes.

Background: Professional soccer players are exposed to considerable impact on the knee during growth that may affect bone morphology and accessory ossicles. Purpose: To identify differences in knee bone morphology, including accessory ossicle development, between soccer players and controls. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The soccer group included male professional soccer players (n = 334 knees) who had medical checkups at the authors’ hospital from 2013 to 2023. Controls were male, age-matched patients at the same hospital (n = 223 knees). Knee radiographs (bilateral anteroposterior, lateral, and sky-line views) were obtained from patients. Each radiograph was evaluated to determine the Insall-Salvati ratio, tuberosity height ratio (THR), posterior tibial slope (PTS), ossicles associated with Osgood-Schlatter disease (OOSDs), Sinding-Larsen-Johansson disease, and bipartite patella (BP). Results: The soccer group had a significantly higher THR (0.276), PTS (9.42°), and incidences of OOSD (10.8%) and BP (6.3%) than the control group (0.213, 8.23°, 3.1%, and 0.45%, respectively) ( P < .001, P < .001, P = .002, and P = .001, respectively). In the soccer group, THR and PTS were significantly higher on the dominant side (0.289 and 9.84°, respectively) than on the nondominant side (0.269 and 9.0°, respectively) ( P = .049 and P = .009, respectively). Conclusion: Elite male soccer players had a larger prominence on the tibial tuberosity, steeper PTS, and higher OOSD and BP incidence. Additionally, they had greater tibial tuberosity prominence and PTS on the dominant side. These findings suggest that repetitive mechanical loading during growth may influence knee bone morphology.