Vacuum clefts of the vertebral bodies

Abstract

Background and purpose: The appearance of vacuum clefts (VCs) of the vertebral bodies has frequently been considered pathognomonic for avascular necrosis. Until recently, this was considered to be a rare finding that might indicate excessive motion at the fracture site. Our aim in this retrospective study was to determine the occurrence and location of these clefts in patients with osteoporotic vertebral fractures and evaluate the risk factors involved for developing these clefts in such patients.

Methods: The records of 66 patients with 101 painful osteoporotic vertebral fractures who were treated by vertebroplasty in our department were reviewed. All the fractures with VCs were collected. Age, sex, degree of deformity, and extent of degenerative changes in the adjacent disk space were compared with those found in the patients without clefts.

Results: VCs were found in 26 fractured vertebrae of 26 patients. They were significantly more common in elderly men who had deformed fractures located at the thoracolumbar junction, when compared with fractures without clefts, especially when degenerative changes were observed in the adjacent disk space.

Conclusion: This study suggests that VCs, which have long been considered pathognomonic for avascular necrosis (Kümmell disease), are not rare and most probably represent fracture nonunion. Elderly patients who have deformed fractures at the thoracolumbar area have a higher risk for developing clefts, mainly when there is degeneration of the adjacent disk space.

Fig 1.

VC associated with an upper endplate fracture.

Fig 2.

VC associated with a fracture of the lower endplate.

Fig 3.

VC passing from the upper to the lower endplate.

Fig 4.

Serial lateral radiographs of a 69-year-old patient from group 2, with severe low back pain following forward bending. A, Initial radiographs demonstrate mild collapse of the upper endplate. B, One month later, a radiolucent line is seen below the fractured endplate. C, Five weeks later, the radiolucent line has disappeared following further collapse of the endplate.

Fig 5.

Radiolucent line is visible, penetrating the degenerative disk above.

Fig 6.

Lateral radiographs of L3 following selective cementation of the cleft.

Fig 7.

Cement leakage to the upper disk via the cleft following cementation of the cleft.

Fig 8.

Pain score in both groups of patients.

Fig 9.

T1-weighted images of fractured vertebrae seen on MR image. On the left, a vertical VC demonstrated as a hypointense line is seen crossing the collapsed vertebra; on the right, no cleft is seen.

Fig 10.

CT reconstruction of a fracture in L2 following vertebroplasty. The cement was injected into the vertebral body and surrounds the sclerotic margins of the cleft without penetrating it.