FACET JOINT ASYMMETRY AS A RADIOLOGIC FEATURE OF LUMBAR INTERVERTEBRAL DISC HERNIATION IN CHILDREN AND ADOLESCENTS

Study Design. This study compared the incidence of facet joint asymmet ry between adult and juvenile patients with lumbar intervertebral disc herniation. Objectives, To determine the different distribution of th e facet joint asymmetry between the adult and juvenile patients. Summa ry of Background Data, As early as 1967, it was suggested that asymmet ry of the facet joints is correlated with the development of disc hern iation. There have been numerous arguments for and against Farfan's hy pothesis; however, most studies were carried out on adult patients, an d this hypothesis has not been verified in juvenile patients.Methods, The study group consisted of 29 levels of 25 patients aged 12-20 years (juvenile group) and 50 levels of 33 patients aged 30-49 years (adult group) who underwent posterior discectomy, The shape of facet joints, the facet joint angle, end the moment arm angle and length were measu red for each facet joint using computed tomography. Facet joint asymme try was defined as the difference in facet joint shape or a difference of more than 10 degrees in facet joint angles between the right and l eft sides. The incidence of facet joint asymmetry and the relationship s among the facet joint asymmetry and the location, type of disc herni ation, and disc degeneration were examined in juvenile and adult group s. Results. The overall incidence of facet joint asymmetry was signifi cantly higher in the juvenile group (12 levels, 41%) than in the adult group (four levels, 8%; P < 0.01). There were no significant relation ships among the facet joint asymmetry, the location, type of disc hern iation, and disc degeneration. Conclusions. This study revealed that t he frequency of facet joint asymmetry in the juvenile group was five t imes higher than that in the adult group. This result indicates that f acet joint asymmetry is a radiologic feature of lumbar intervertebral disc herniation in children and adolescents.