Slipped vertebral epiphysis (report of 2 cases).

Avulsion or fracture of posterior ring apophysis of lumbar vertebra is an uncommon cause of radicular low back pain in pediatric age group, adolescents and athletes. This lesion is one of differential diagnosis of disc herniation. We reported two teenage boys with sever low back pain and sciatica during soccer play that ultimately treated with diagnosis of slipped vertebral apophysis.

Slipped vertebral apophysis (Apophyseal Ring Avulsion) is very rare.1–14 This lesion occurs in pediatric age group and young adult because fusion between ring apophysis and vertebral body do not occur fully until the skeletal growth, i.e. the age of 18-25 years. In children and young adults, specially in ath-letes, diagnosed for lumbar disc herniation, this lesion may be the proper diagnosis.3578911 Although most of these lesions occur in lower lumbar area479111516, we saw these lesions in upper lumbar region as presented below.

Case presentation

We presented two boys with sever low back pain and sciatica during soccer play.

Case one was 13 years old and had severe sudden onset low back pain with radiation to anterior aspect of right thigh during extension of leg. Muscle powers and deep tendon reflexes were in normal range. The patient had flexion posture due to severe back pain. His pain was in territory of right L3 root. He was managed conservatively for 2 months but there was no significant improvement.

Computerized tomography at L2-L3 level (Figure 1) showed a bony fragment similar to an osteophyte extending to canal. In lumbosacral MRI we detected a L2-L3 disc bulging with impingement of L3 root and thecal sac compression (Figure 2–3). The second case was 14 years old and had sudden onset low back pain with radiation to right lower extremity for one month. He had pain in territory of L5 root with intact muscle power and deep tendon reflexes. He had positive straight leg raising test (SLR test).

Figure 1

Computerized CT-scan from L2-L3 intervertebral disc. Note the avulsed bony particle from apophyseal rim

Figure 2

Intervertebral disc herniation at level of L2-L3 in sagittal view

Figure 3

MRI (axial view) from L2-L3 inter vertebral disc

Lateral lumbosacral radiography showed a small bony extension into vertebral canal at L4-L5 intervertebral disc level (Figure 4). He was disable and had no recovery after several medical and conservative management and physiotherapy.

Figure 4

Lateral lumbosacral X-ray .Small bony particle adjust to posterior margin of L4 rim is seen

In his lumbosacral MRI, he had a herniated L4-L5 disc herniation with compression effect on the thecal sac and right L5 root (Figure 5).

Figure 5

MRI(axial view) from L4-L5 inter vertebral disc

Due to failed conservative management by other referral centers, we operated them in prone position. Extensive bilateral laminectomy was done. Good exposure was achieved after removal of adhesive tissue and epidural fat. Avulsed, hard and sharp particles of the posterior rim of vertebral body, including overlying cartilage of the annulus fibrosus similar to Takata classification type-II were seen. These particles were irregular in shape because there was some bone in the fragment. Associated herniated intervertebral disc was also seen. Retropulsed bony fragment was removed after careful separation from peripheral tissue. Then herniated intervertebral disc was removed through diskectomy procedure. Their problems were completely relieved after the operations.

Discussion

Superior and inferior surface of a developing vertebra are covered by thin cartilaginous plate. These cartilaginous plates are thickened peripherally and called ring apophysis.

The calcification of the cartilaginous rim occurs around age 13 and fused with the vertebral body by the end of skeletal growth, i.e. by the age of 18-25 years.3791011

The development occurs at different rates in various spinal segments. The progress is faster in females than in males. Intervertebral disc of immature spine is fastened to the ring apophysis by the outermost fibers of annulus fibrosis (Sharpey's fibers).3 Avulsion of lumber vertebral apophyseal rim is very rare and there are two possible mechanisms by which the fracture can occur. First, the force transmitted to Sharpey's Fibers by annulus pulpous during herniation may cause disruption at the weak point of osteocartilagenous junction, thus resulting in an avulsion fracture. Second, migration of the nucleus pulpous may occur through the weak point, similar to the mechanism which results in limbus vertebra.3710

Apophyseal avulsion is a very rare lesion and accurate diagnosis is often delayed because of concerns for neoplasm, infection and spondylolisthesis.411–1317

Takata et al3 have classified these fractures in three types on basis of CT-scan studies: type I, a simple separation of the entire arcuate posterior margin of the vertebra, type II, an avulsion fracture of the posterior rim of the vertebral body, including the overlying cartilage of the annulus fibrosus, resulting in a thicker and larger fragment and type III, a more localized fracture involving a large amount of the vertebral body so that the resulting fragment is larger than the vertebral rim.317 According to Takata classification, type I and type II can be treated conservatively and type III and IV require surgical intervention. Surgery is also indicated when there is a failure of conservative treatment.

Epstein et al proposed an additional cate-gory: type IV, a fracture of both cephalad and caudal end plates, which spans the full length of the posterior margin of vertebral body.317

These fractures need to be accurately diagnosed compared to simple disc herniations, specially in children and adolescents.56711 These type of fractures require more suspension and knowledge for diagnosis and need more extensive exposure during laminectomy for better resection of pathology and decompression of nerve roots.313 So, unilateral laminatomy is not recommended in these patients because mobile and sharp retropulsed particle can displace cephalad or caudal and can damage neural structures.

For early detection of epiphyseal fracture, computerized tomography is recommended to show bony component of herniated material.6912

Computerized tomography scans can be a good diagnostic technique for early detection of epiphyseal slipping, so we recommend it.

Authors’ Contributions

MRF: Carried out the design, coordinated the study and participated in most of the experiments and prepared the manuscript.

MSM: Participated in manuscript preparation.

All authors have read and approve the content of the manuscript.