Clinical significance of ring apophysis fracture in adolescent lumbar disc herniation

Study Design. Retrospective review and post-test-only control group design. Objective. To study the incidence and associated factors of ring apophysis fracture in adolescent lumbar disc herniation and to evaluate the long-term morbidity of untreated apophyseal fracture. Summary of Background Data. Ring apophysis fracture is a feature in adolescent disc herniation, but the incidence and prognosis are unknown. It is still controversial whether to remove the apophyseal fragment at time of discectomy. Methods. We studied 96 adolescents (mean age, 14.7 years) with clinical diagnosis of disc herniation proved by computerized tomography (CT). In CT scan ring, apophyseal fracture is classified by the size (large/small) and the location (central/lateral). We used modified Oswestry classification in the nonoperative patients for pain and functional evaluation. Patients with and without apophyseal fracture were compared to define the significance of the lesion. Results. Twenty-seven of the 96 CT studies (28%) demonstrated apophyseal fractures. All but 2 were at the level of the herniated disc. Large-central fragments were the most common in 16 patients (48%), large-lateral fragments in 2, small-central fragments in 6, and small-lateral fragment in 6. Rate of surgery was significantly higher in the disc herniation patients with apophyseal fractures. Sixty-four nonoperative patients were evaluated 6.6 years (range, 2.3-14.3) after the CT study and questionnaires were completed in 54 patients (84%). Patients with large apophyseal fragments had more chance of chronic back pain and limitation of daily activities than the patients with small fragments and patients without apophyseal fracture. Conclusion. Apophyseal fracture is not uncommon in adolescent lumbar disc herniation. The surgical decision must depend on clinical symptoms instead of radiologic findings, but disc herniation with apophyseal fracture may exhibit more severe symptoms. Patients with large apophyseal fragments must be informed of a greater chance of chronic back pain later on. Small apophyseal fragments had no clinical significance.