Abstract
BACKGROUND: Sumo wrestling is a traditional sport in Japan and becoming popular worldwide. Risk factors for lower back injuries in sumo wrestlers are heavier weight and larger body mass index (BMI). The mawashi (loincloth belt) worn by sumo wrestlers has been shown to restrict motion of the lumbar spine. PURPOSE: To study the effects of sumo wrestling on the lumbar spine of high school and freshmen collegiate wrestlers, investigating the relationship between radiological findings, wearing of the mawashi during training, and lower back symptoms. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: From 2001 to 2017, a total of 197 members of the Japanese Sumo Federation (55 high school and 142 college freshman students) underwent routine radiographic examination of their lumbar spines and answered a questionnaire regarding lumbar symptoms. Wrestlers were classified as symptomatic and asymptomatic based on responses to a custom questionnaire. We used the unpaired t test to evaluate patient demographics and the chi square test to analyze radiographic lumbar spine abnormalities between symptomatic and asymptomatic wrestlers. RESULTS: The wrestlers' mean height, weight, BMI, and duration in the sport were 174.0 ± 6.7 cm, 107.1 ± 22.4 kg, 35.2 ± 6.4, and 8.0 ± 3.2 years, respectively. There were 91 participants in the symptomatic group (46.2%) and 106 (53.8%) in the asymptomatic group. Ten wrestlers (5.1%) had osteophyte formations in the lumbar body; 8 of the 11 osteophytes (72.7%) appeared in the upper lumbar spine. Of the total, 48 wrestlers (24.4%) had deformities (Schmorl nodules) in the lumbar body, and 23 of 50 (46.0%) and 10 of 16 (62.5%) deformities were found in the upper lumbar spine of collegiate and high school wrestlers, respectively. Five wrestlers of the total 197 athletes (2.5%) had disc space narrowing in the lumbar body, with 3 of the 5 cases of disc space narrowing (60.0%) found in the upper lumbar spine. Spondylolysis in the lumbar body was found in 25 wrestlers (12.7%); 19 of the 91 symptomatic wrestlers (20.9%) had spondylolysis, compared with 6 of the 106 (5.7%) asymptomatic wrestlers (P = .0028). CONCLUSION: Almost one-third of sumo wrestlers had ≥1 abnormal radiological finding in the lumbar spine. There was a significant relationship between symptomatic wrestlers and spondylolysis.