Sports MedicineThe Passive Mechanical Properties of Muscles and Tendons in Children Affected by Osgood-Schlatter DiseaseEnomoto, Shota MA*; Tsushima, Aiko MD†; Oda, Toshiaki PhD‡; Kaga, Masaru PhD§Author Information *Joint Graduate School in Science of School Education ‡Health and Life Sciences, Hyogo University of Teacher Education, Kato, Hyogo †Division of Developmental Studies and Support §Graduate School of Education, Okayama University, Kita-ku, Okayama, Japan No funding was received in support of this study. The authors declare no conflicts of interest. Reprints: Shota Enomoto, MA, Joint Graduate School in Science of School Education, Hyogo University of Teacher Education, 942-1, Shimokume, Kato, Hyogo 673-1494, Japan. E-mail: firstname.lastname@example.org. Journal of Pediatric Orthopaedics: April 2020 - Volume 40 - Issue 4 - p e243-e247 doi: 10.1097/BPO.0000000000001426 Buy Metrics Abstract Background: Osgood-Schlatter disease (OSD) is a sports-related disorder involving apophysitis, which affects the tibial tuberosity. The identification of factors related to OSD is important for its prevention and early recovery from the disease. This study aimed to compare the passive mechanical properties of the muscle-tendon unit in children affected by an OSD and healthy children, by using ultrasound real-time tissue elastography. Methods: Eighteen legs affected by OSD (OSD group) and 42 healthy legs (control: CON group) were assessed. The elasticity was obtained from the quadriceps muscles and patella tendon (PT) using real-time tissue elastography. The strain ratio (SR; muscle or tendon/reference ratio: strain rate of the muscle or tendon divided by that of the reference material) was calculated as an indicator of the elasticity of the tissue of interest. Results: The SR of the PT in the OSD group was significantly lower than that in the CON group (P<0.05). We found no significant difference between the groups in terms of the SR value of all muscles (P>0.05). Conclusions: The results suggest that a PT with a lower SR may be associated with an OSD and that the passive mechanical properties of the quadriceps muscles have limited association with an OSD. Levels of Evidence: Level IV. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.