Five contortionists who trained in the circus school in Inner Mongolia were evaluated by magnetic resonance imaging, MRI. The authors of the study were interested in the effect of extreme body contortions on the spine. The subjects were all females, between the ages of 20 and 49 years. Each started intense training between the ages of six to 12.
Interestingly dynamic, whole spine MRIs were acheived in two of the subjects. These subjects were in contorted positions when imaged.
The authors discovered that anterosuperior limbus avulsion fractures were found in three out of the five subjects. One subject had limbus fractures at two levels. A limbus fracture involves a fracture of the end plate of a vertebral body. Risk factors for limbus fractures include young age and skeletal immaturity. Prior to complete fusion as the skeleton becomes mature, the junction of the disc and the vertebral body can be prone to injury. In these subjects, it is hypothesized that chronic and repetitive stresses into spinal extension resulted in the limbus fractures.
Straightening of the cervical lordosis in supine was noted in all five of the subjects. Dextroscoliosis was also noted in all five subjects. Older athletes demonstrated more severe degenerative changes of the spine. They also had more complaints of back pain. Osteophytes, disc bulges and annular tears were also found on imaging. While range of motion in flexion was perceived as normal, extension of the spine was increased.
The Beighton system to grade hypermobility was used on the subjects. The maximum score is nine, meaning greater hypermobility. A score greater than or equal to five is considered hypermobile. Four of the five subjects had a score of nine, and the fifth subject had a score of seven.
In summary, the authors felt that the degree of pathology in the spines of the contortionists was limited considering the degree of stress placed on their spines, particularly in extension.