Vertebral injection treatments of fractured or pathologically weakened bone are an important advancement in the management of painful vertebral compression fractures and vertebral metastases. Vertebroplasty introduces a low viscosity cement under relatively high pressure to fill minor voids and the interstices of the cancellous bone. Kyphoplasty involves the creation of a large cavity within the vertebra using an inflatable bone tamp. The creation of this large defect can reduce kyphotic deformity, restore vertebral body height, and allows for the injection of a higher viscosity cement under lower injection pressure. These two procedures are discussed in the article, “Percutaneous Vertebroplasty: New Treatment for Vertebral Compression Fractures,”1 in this issue of American Family Physician.
The indication for vertebral injection therapy must be more selective than just the diagnosis of fracture, metastasis, or hemangioma. Complications from these procedures can occur and, occasionally, are fatal. Cement intrusion into the spinal canal may require emergent decompression for removal and protection of the neural elements.
Patients with severe pain and functional disability from compression fractures who have failed treatment with bracing and analgesia are certainly candidates for vertebral cement injection. Radiographic scans should show acute or subacute fractures. Healed fractures are unlikely to benefit from injection therapy. Without significant wedging or kyphosis, vertebroplasty is appropriate. With multiple fractures and mild kyphosis or single fractures with significant kyphosis, kyphoplasty may provide better long-term results by restoring vertebral height and correcting deformity.
For painful metastatic lesions and impending fracture and pain, cement injection can be helpful in improving function and reducing pain. In these circumstances, vertebroplasty is the procedure of choice. Involvement of the posterior vertebral body wall is a relative contraindication, and injection therapy in these patients should only be performed by physicians who have a large experience with these procedures.
Simple vertebral hemangiomas are common and are usually incidental findings on radiographs in patients with back pain. Aggressive hemangiomas with soft tissue extension or pathologic fractures may well be amenable to vertebral cement injection. A preinjection vertebrogram must be performed to ensure that the cement will not pass directly into the venous system; preinjection vascular embolization may also be useful.
Consultation with a subspecialist in spine surgery should be considered before referral for a vertebral cement injection. The decision to be invasive, even minimally invasive, should not be taken lightly. Certain clinical situations may be more appropriate for vertebroplasty or kyphoplasty, or may occasionally require open spinal surgery for additional posterior vertebral body fracture and collapse with spinal canal compromise. Most clinical situations do not require invasive therapy because most fractures will heal uneventfully and cause little functional loss.
Recently, there has been increasing interest in vertebroplasty and kyphoplasty for the management of acute vertebral fractures. However, neither technique has been subjected to controlled trials to demonstrate any benefit over traditional medical management.2 Long-term studies have not been performed to evaluate possible complications, which could include local acceleration of bone resorption caused by the treatment itself or by foreign-body reaction at the interface of cement and bone, and increased risk of fracture in treated bone or adjacent vertebrae.3 Until conclusive evidence is available, these procedures should only be performed in carefully selected patients.