3. Risk factors and frequency of occurrence of lumbar spine disease in young male American football players - A 6-year cohort study using lumbar spine MRI and X-rays

BACKGROUND CONTEXT

N/A

PURPOSE

It is known from experience that the risk of lumbar spine disorders such as lumbar disc herniation and lumbar spondylolysis is increased in American football players. However, no large-scale prospective study has been conducted, and the risk factors and frequency are not clear. The purpose of this study is to investigate the risk factors and frequency of occurrence of lumbar spine disease among young male American football players.

STUDY DESIGN/SETTING

N/A

PATIENT SAMPLE

N/A

OUTCOME MEASURES

N/A

METHODS

We enrolled 306 subjects, who gave consent to participate in this study, between 2005 and 2017. All subjects were male, aged 15-16 years (first-year of high school students in Japan). We evaluated subjects’ demographic data (height, weight, BMI, and position in American football), lumbar spine MRI and X-rays which were taken at the start of competition, 3 years, and 6 years later.

RESULTS

Of the 306 subjects, 103 (33.7%) could be successfully followed up to the last observation. The subjects with Pfirrmann classification grade IV or higher disc degeneration as assessed by MRI, significantly increased from 8.8% at the start of competition, to 33.3% at 3 years later and 48.0% at 6 years later (p<0.001). The progression of disc degeneration on MRI was frequently observed in L4/5 and L5/S levels at final follow up (L1/2; 1.0%, L2/3; 1.0%, L3/4; 4.9%, L4/5; 25.5%, L5/S1; 32.4%). The position of lineman was the only risk factor for the progression of disc degeneration (p=0.049). The subjects with herniated discs protruding more than 5 mm from the posterior wall of the vertebral body, significantly increased from 3.9% at the start of competition, to 23.5% at 3 years later and 33.3% at 6 years later (p<0.001). The prevalence of lumbar disc herniation on MRI at final follow up were L1/2; 1.0%, L2/3; 0%, L3/4; 0%, L4/5; 25.5%, and L5/S1; 32.4%. Lineman, weight, and BMI were risk factors for disc herniation (p=0.015, 0.013, 0.019 each), but the results of differential analysis by each position showed that neither weight nor BMI differed significantly in any position (p<0.05). X-ray findings revealed that the rate of lumbar spondylolysis was 3.9% at the start of competition, compared to 7.8% at 3 years later and 9.8% at 6 years later, but this change was not statistically significant (p = 0.17).

CONCLUSIONS

From this study, it was found that American football competition was a risk for the progression of disc degeneration and herniation in lower lumbar. Especially, the position of lineman seemed to be involved with significant risk factors, and body weight and BMI were confounding factors. Previous reports have shown differences in disc degeneration and herniation occurrences in lower lumbar depending on the athletic competition type. It was expected that the playing characteristics of American football competition, which are quite different from one position to another, would result in differences in the risk of lumbar spine disease occurrence.

FDA Device/Drug Status

This abstract does not discuss or include any applicable devices or drugs.