Background: Although iliopsoas disorder is one of the most frequent causes of groin pain in athletes, little is known about its prevalence and clinical impact. Methods: We retrospectively reviewed the cases of 638 consecutive athletes who had groin pain. Each athlete was assessed with magnetic resonance imaging (MRI). First, we identified the prevalence of changes in signal intensity in the iliopsoas. Then we classified the changes in signal intensity in the iliopsoas, as visualized on short tau inversion recovery MRI, into 2 types: the muscle-strain type (characterized by a massive high-signal area in the muscle belly, with a clear border) and the peritendinitis type (characterized by a long and thin high-signal area extending proximally along the iliopsoas tendon from the lesser trochanter, without a clear border). Finally, we compared the time to return to play for the athletes who had these signal intensity changes. Results: Changes in signal intensity in the iliopsoas were detected in 134 (21.0%) of the 638 athletes. According to our MRI classification, 66 athletes had peritendinitis changes and 68 had muscle-strain changes. The time from the onset of groin pain to return to play was significantly shorter for the patients with muscle-strain changes on MRI than for those with peritendinitis changes (8.6 ± 8.3 versus 20.1 ± 13.9 weeks, respectively; p < 0.0001). Conclusions: Changes in MRI signal intensity in the iliopsoas were observed in 21.0% of 638 athletes who had groin pain. Distinguishing between muscle-strain changes and peritendinitis changes could help to determine the time to return to play.

Background/Objectives: Long-standing groin pain is a severe issue for athletes, often associated with the cleft sign on magnetic resonance imaging (MRI) scans, yet its underlying causes are poorly understood. The purpose of this study is to histologically examine the pubic plate structure in cadavers with and without the cleft sign on MRI, shedding light on the pathology behind the cleft sign. Methods: Three fresh human pelvic cadavers underwent 3.0T MRI to detect the cleft sign before histological dissection of pubic plates. Pubic plate tissues were fixed in formalin, decalcified, and processed. Of the two cleft sign-negative specimens, one was cut into sagittal sections, and the other was cut into coronal sections for histology. For the cleft sign positive specimen, a sagittal section was cut. Moreover, 5 µm thick sections were cut at different axial levels for each orientation. Sections were subjected to Safranin O, Alcian blue, and Herovici’s staining or hematoxylin and eosin staining. Results: MRI confirmed that one specimen had a cleft sign in the inferior region on both sides of the pubis and that two specimens had no cleft sign. Both sagittal and coronal sections showed the presence of a cartilage structure continuing from the pubic symphysis to 3 mm laterally within the pubic plate. In the specimen with a positive cleft sign, cartilage damage within the pubic symphysis and pubic plate was identified as revealed by Safranin O staining, Herovici’s staining, and H&E staining. Conclusions: This study elucidated the existence of a cartilage component extending from the pubic symphysis to the pubic plate. The cleft sign in MRI correlated with a disruption in the cartilage component in histology within this specific area.

Objectives: Early protective motion (EPM) treatment, using a rigid functional knee brace for acute anterior cruciate ligament (ACL) injuries, has been reported to restore ACL function. This study aimed to investigate the probabilities of return to sports and reinjury rate associated with EPM treatment and the result of restoring ACL function and morphology in MRI more than 2 years after injury in patients with acute injured ACL. Methods: This study included sports players with primary acute ACL injuries, straight-shaped tears and normal-volume bands on sagittal MRI, with a minimum of 2-year follow-up. If the ACL is treatable based on MRI, Lachman test and KT-1000 measurements after 3 months of knee brace use, EPM treatment can continue. The time of RTS, reinjury rate and KT measurements before and after treatment were analysed. In addition, the reinjury group and the non-reinjury group were compared. Results: Thirty-one patients participated in this study. KT measurements at injury, brace removal and final follow-up were 5.8 mm (IQR, 4.5–7.0), 0.0 mm (IQR, –0.5–0.5) and 0.0 mm (IQR, 0.0–0.5), respectively. 77.4% returned to sports at their preinjury level and had ACL repair on MRI after more than 2 years post-injury. Reinjury occurred in 22.6%, with no significant demographic differences between the reinjury and non-reinjury groups. Conclusion: After EPM treatment with at least 2 years of follow-up, 77.4% of patients returned to sports with restored ACL function. MRIs taken over 2 years post-injury confirmed ACL morphology repair, following strict case selection based on MRI within 2 weeks of injury.