ABSTRACT
STUDY DESIGN: A case report and a biomechanical study using a finite element method. OBJECTIVES: To report a case with the cervical spondylolysis and to understand the biomechanics of the cervical spine with spondylolysis at C6. Cervical spondylolysis, although not a common spinal disorder, can occur in athletes. Presently, the exact pathology, natural history and biomechanics are not known. Thus, treatment strategies for this disorder in athletes are in controversy. To treat and/or advise patients with cervical spondylolysis, the cervical spine biomechanics regarding this disorder should be understood. METHODS: A case of a 12-year-old male judo player is presented. The patient presented with occipital and upper neck pain. Plain radiographs, reconstructed CT scan and MRIs of this patient were reviewed. Biomechanically, stress distributions were analyzed in response to 73.6 N axial compression and 1.5-Nm moment in flexion, extension, lateral bending, and axial rotation using a FE model of the intact ligamentous C3 to C7 segment. Bilateral spondylolysis was created in the model at C6. The stress results from the bilateral defect model were compared to the intact model predictions. RESULTS: Plain radiographs showed bilateral C6 spondylolysis, and grade I spondylolisthesis. MRI showed mild disc degeneration at C6/7. With conservative treatment, the symptoms disappeared. In the spondylolysis model, the maximum Von Mises Stresses at C6/7 increased in all cervical spine motions, as compared to the intact case. Specifically, in axial rotation, the stress increase was 3.7-fold as compared to the intact model. The range of motion at C6/7 increased in the spondylolysis model as well. Again, during axial rotation, the increase in motion was 2.3-fold when compared to the intact model. CONCLUSIONS: Cervical spondylolysis can cause biomechanical alterations, especially in axial rotation, leading to increased disc stresses and range of motion. The increased stresses in the disc and the hypermobility would be a dangerous condition for athletes participating in contact sports such as judo. Thus, we recommended that judo players with cervical spondylolysis should change to non-contact sports, such as jogging.
