Effects of high load on the growing spine. Experimental studies anda long-term follow-up of top athletes

Abstract

A high prevalence of radiological abnormalities of the spine has been reported in some physically demanding sports. The significance and aetiology of these radiological abnormalities are still a matter of controversy and the long-term effects are not known. The injury patterns were studied in 16 adolescent human cadaveric spinal motion segments (vertebra-disc-vertebra) when axially compressed to failure. Injuries were found in the region of the growth plate of the vertebral body. This injury pattern differs from that in earlier studies of adult spines, where fractures to the spongious bone under an intact endplate were found. Adolescent porcine spinal lumbar motion segments were axially compressed to failure. In all cases, on microscopic and histological examination, a fracture line could be seen through the epiphyseal plate and through the growth zone. The fracture site was filled with material from the nucleus pulposus and there was a loss of nucleus content in the disc. The injuries could be seen on magnetic resonance imaging but not on plain radiography. By comparison, when axially compressed to failure, adult porcine motion segments did not show this type of injury. Instead there was a fracture of the vertebra or a rupture of the anulus fibrosus. Radiological changes in the thoraco-lumbar spine and the frequency of back pain were investigated in a 12-15-year follow-up study of 135 top athletes and a reference group of 28 non-athletes. Radiological abnormalities of various types were found in all the groups of athletes and non-athletes, but they were more common among athletes, especially male gymnasts and wrestlers. A deterioration in the disc height during the follow-up period was significantly more common among wrestlers than non-athletes. There was no significant correlation between the number of radiographic abnormalities and back pain. Despite a higher frequency of radiographic abnormalities among the groups of athletes, they did not report significantly more back pain than non-athletes. However, a decrease in disc height between the two examinations correlated significantly with back pain at follow-up. In conclusion, the study supports the view that the spine is most vulnerable to athletic trauma during the growth period. Injuries to the disc in particular appear to be at risk of long-term radiological deterioration and subsequent back pain.