Conventional therapy for osteoporotic vertebral fractures consists of analgesics, bed rest, physical therapy, and occasionally bracing. Some of these patients will go on to prolonged intractable pain, putting patients at risk for major complications from immobilization. Other than vertebroplasty, there is no alternative treatment.
Percutaneous vertebroplasty is a new, minimally invasive outpatient procedure whereby vertebral compression fractures are stabilized by injection of bone cement or polymethlymethacrylate (PMMA). The technique was pioneered in France and first performed in 1984 by H. Deramond. It has become popular in the United States for treatment of intractable pain due to osteolytic metastasis, multiple myeloma, hemangioma lymphoma, and osteoporotic vertebral collapse. Rapid partial or complete pain relief can usually be achieved through this procedure.
The ideal patient is one with painful vertebral compression fracture secondary to osteoporosis or tumor infiltration that has failed nonoperative treatment. It is also indicated for painful vertebral hemangiomas with or without fractures. At the present time, prophylactic vertebral body strengthening for prevention of fractures is not indicated.
A patient with coagulopathy, retropulsion of bone, or epidural tumor causing significant thecal sac compression or neural foraminal narrowing with neuralgia is a contraindication. Significant vertebral body collapse to less than one-third of its height is a relative contraindication.
A multidisciplinary team approach is essential for proper patient selection. An orthopedist, an oncologist, and a neuroradiologist see all of our patients. Plain x-rays, CT scan, and MRI scans are performed on all patients. Using a reflex hammer, percussion pain is correlated to the imaging abnormalities.The MRI scan is crucial to exclude patients with significant vertebral plana, neural foraminal, or significant thecal sac compromise from bony retropulsion or epidural tumor. MRI is useful in guiding vertebroplasty in those patients with multiple vertebral compression fractures where it may difficult to select the appropriate vertebral body for treatment.
A CT scan through the fracture with the patient in prone position is essential for guiding needle placement under fluoroscopic guidance. It is particularly important with mid thoracic vertebral compression fractures where a parapedicular approach may be necessary. The exact entry point and angle of the bone biopsy needle can be calculated using the planning CT scan, making the procedure significantly safer. Others use CT or a combination of CT/fluoro to inject the PMMA.
Thirty minutes prior to the procedure, 1 gm IV of Ancef and 10 mg IV of Decadron is given. For sedation we use IV Fentanyl 50 mcg, and Versed 5 mg prn. With the patient prone on the angiogram table, the exact entry point is marked on the patient’s back using steri-strips. The current transpedicular or parapedicular entry point is confirmed by rotating the fluoroscopic tube. Placing the pedicles symmetrically between the endplates of the appropriate vertebral body, or by measurements from the prone lateral scout view of the patient’s spine CT scan, easily determines the correct craniocaudal angulation.
Liberal local anesthesia with Lidocaine is given. Using a Cook Osteo-site bone biopsy needle (11 or 13 gauge), this is placed at the entry point perpendicular to the fluoroscopic tube, giving a bulls-eye appearance. When the needle tip reaches the vertebra, a gentle tap with an orthopaedic hammer is used to guide the needle into the anterior one-third of the vertebral body. Many authors advocate venogram prior to cementing to confirm that the needle tip is not within the venous plexus. Venography is not performed at our institution as the norm at other centres.
Chilled Codman cranioplastic polymer powder is mixed with 1.5 vials (9 gm of sterile barium sulfate). The mixed powder is divided into 2 portions and monomer added to one portion and mixed to a thin paste. The mixture is loaded into a 10 cc syringe which allows the cement to be placed into smaller 1 cc syringes. The cement is injected through the bone biopsy needle under close fluoroscopic guidance. The procedure is terminated when the cement reaches the posterior one-third of the vertebral body, or paravertebral/epidural venous filling is seen. The patient then lies on the table for approximately 15 minutes without weight-bearing while the cement hardens.
The patients receive bed rest for 2-3 hours and a follow-up CT scan through the treated level. The patients are discharged home in 3-4 hours. All the patients are followed up by telephone at 1 day, 2 days, 4 days, 7 days, 2 weeks, 4 weeks, 8 weeks, and 12 weeks. They are also followed up in bone metastases clinic and orthopedic clinic in 2 weeks.
There are numerous case series and open studies showing promising results with low complication rates for both osteoporotic fractures and pathological fractures. Significant pain relief is afforded in 80 per cent of patients with pathological fractures and in over 90 per cent of patients with osteoporotic fractures. The pain relief seems to persist with time.
Complications are minor, relatively infrequent and usually transient. Good fluoroscopy and controlled injection of PMMA is essential in avoiding complications. There are anecdotal reports of cord compression, transient worsening of pain, radicular pain, infection, and spinal cord compression. There is one reported case of symptomatic pulmonary embolism from leakage into the epidural veins in a patient with vertebral Langerhan’s cell histiocytosis. Two patients sustained single nondisplaced rib fractures during insertion of the bone biopsy needle.
Extravertebral extrusion of PMMA is common, seen in up to 73 per cent (29/40) of patients with metastatic disease. Although this series reported 2 out of 37 requiring decompression back surgery for significant neurological complications, most series report no clinical sequela of cement leakage. Intradiscal extrusion of cement has been reported to cause a slight increase in adjacent vertebral fracture.
Percutaneous vertebroplasty is a promising new therapy for intractable pain associated with tumor-induced or osteoporotic-induced compression fractures. The patient often experiences significant and rapid pain relief following the procedure, with a low complication rate. We believe that a multicentre prospective randomized trial comparing percutaneous vertebroplasty with conservative therapy is needed to prove the safety and efficacy as well as to clarify the indications for the procedure.
In development are new injectable physiologic bone materials that can induce bone formation or incorporate itself with bone. Drugs such as chemotherapeutic agents or antibiotics may be delivered in concert with the cement.
In those patients with severe kyphosis causing difficulty breathing and eating, a new procedure, “kyphoplasty” can restore vertebral body height by placing a high-pressure balloon within the vertebral body and cement injected. Prophylactic treatment of osteoporotic vertebrae and prophylactic treatment of vertebral bodies infiltrated by tumor needs to be assessed.