Disc herniation is most common in adults. But it can occur in children, specifically adolescents (teenagers). In about one-third of these herniations, there is a fracture of the apophyseal ring. Treatment of the ring apophysis fracture associated with disc herniation is the subject of this study.
The apophyseal ring is a tough, fibrous structure around the outer portion of the vertebral body next to the disc. It is attached to the outer portion of the disc called the anulus fibrosus. The ring apophysis attaches the anulus fibrosus to the vertebra. The ring provides an area of denser, stronger bone for the edge around the vertebral bone.
A fracture of the ring indicates that the fibrous ring (along with a small piece of bone still attached) has pulled away from the vertebra. This can occur along the upper (above) or lower (below) endplate of the affected disc. It appears to be caused more by repetitive stress rather than a single traumatic event. Many of the athletes who have a ring apophysis fracture don’t even know it.
Because of the rarity of this condition, long-term studies of many patients haven’t been possible. Thus, it’s not clear what treatment is best. Should the fractured part of the ring be removed when the disc is taken out? What happens later in life if the ring is or isn’t removed?
To answer these questions, the authors studied 96 adolescents between the ages of nine and 18 years old. All had back and leg pain from a disc protrusion in the lumbar spine. The diagnosis was confirmed with CT scans.
Each case was classified according to the location where the bone was pulled away from the vertebral body. This could be central (or middle) and lateral (or side). It was also categorized by size (large or small). Large was anything that measured more than 50 per cent of the width of the posterior wall of the vertebral body.
An analysis of the cases showed that patients with disc herniation and apophyseal ring fractures were more likely to have surgery. Age didn’t seem to predict who would or would not have a ring fracture. Males were affected twice as often as females. Level of disc herniation and history of injury were not linked with apophyseal fractures either.
One-third of the 96 patients had surgery (discectomy with or without removal of the apophysis fragments). Two-thirds were treated nonoperatively. Of the patients with lumbar disc herniation AND apophyseal ring fractures, more than half had surgery. Twenty-five per cent of the patients with disc herniation alone also had surgery. The difference between these two groups may have been severity of pain.
Patients with large apophyseal fragments had the greatest risk for a poor outcome. They were more likely to have chronic back pain years later. Small fractures did not seem to have any negative long-term effects.
The authors conclude that disc herniation with ring apophysis fracture does not require surgery because of the fracture. The surgeon makes the decision to operate based on the patient’s symptoms, not on X-ray or CT findings. It is likely that patients with both a disc herniation and fracture will have more pain than someone with just the disc herniation. Large, central fragments that are not removed pose the greatest risk for future problems.