Fracture of posterior margin of lumbar vertebral body

Background: Avulsion or fracture of posterior ring apophysis of lumbar vertebra is not a common clinical entity and is missed often. These fractures are mostly traumatic lesions typically seen in adolescents and young adults, because fusion in this area is not complete until the age of 18 to 25 years. These fractures are occult on plain radiographs and are frequently missed due to unfamiliarity with the entity. But, CT scanning and MR imaging shows characteristic picture. Methods: We had 21 cases of fracture of posterior margin of a lumbar vertebral body from 1991 to 2002. Fracture in all patients were classified according to CT imaging, into the three types described by Takata et al. Out of these, 8 patients were of type I, 4 patients of type II and 9 patients of type III respectively. Focal deficit / muscle weakness was present in only three patients. No fractures of type IV (Epstein et al) was found. Twelve patients were treated conservatively and 9 patients were treated by posterior decompression with total laminectomy and removal of retropulsed fragment and discectomy. Results: The mean follow-up period was of 42 months. Conventional radiography could locate the fracture in only 6 cases and CT scan was required in all cases for stamping the diagnosis and classification. Though it is uncommon, high index of suspicion is required to diagnose it, in especially adolescent patients. All the 21 patients had good outcome following the management. Conclusion: Avulsion or fracture of posterior margin of lumbar vertebral body is not so rare entity. In children and young adults diagnosed as having lumbar disc herniation, this lesion may be the proper diagnosis. These fractures need to be accurately diagnosed because as compared to simple disc herniations these fractures require more extensive exposure and resection to relieve the nerve impingent.