Multiple myeloma is an incurable blood cancer of the plasma cells. However, the expansion of novel treatments has significantly prolonged overall survival to the extent that it can now be considered more of a chronic disease. During the illness trajectory, bone destruction is the most frequent cause of patient morbidity and mortality.1,2 Symptomatically, bone involvement afflicts 70% to 100% of patients with myeloma and leads to distressing skeletal pain related to a variety of complications including pathological fractures, vertebral body collapses, and hypercalcemia.1-5 The challenge is to effectively manage both bone pain and vertebral compression fractures (VCFs). This article reviews the role of vertebroplasty as an effective intervention in the treatment of symptomatic vertebral compression fractures in patients with multiple myeloma.
MYELOMA BONE DISEASE
Multiple myeloma is a blood cancer that leads to the transformation of plasma cells, a type of white blood cell located within the bone marrow, resulting in an overproduction of monoclonal immunoglobulins. These plasma cells proliferate at an unrestricted rate, overcrowding the marrow and diminishing the production of other normal cells. In healthy bones, bone remodeling is a seamless process whereby osteoclasts break down old or damaged bone, and osteoblasts lay down new bone. In patients with myeloma, malignant plasma cells within the bone marrow release cytokines that cause the surrounding bone to break down faster than it can be repaired. This process upsets bone metabolism by creating an imbalance between osteolytic and osteoblastic activity, which promotes the removal of compact bone.1,3 This leads to a vicious cycle of perpetual bone loss accompanied by a spreading of myeloma plasma cells, and eventually bone destruction.3 Patients with myeloma are then susceptible to both diffuse loss of bone mass, as well as the development of focal bone lytic lesions, which increase the risk of fracture. Of these skeletal-related complications, the vertebral bodies of the spine are the most likely to be affected by multiple myeloma.1,4,6
When myelomatous lytic lesions involve the vertebrae, vertebral stabilization is of utmost importance to prevent the sequelae of a compression fracture. Vertebral compression fractures are associated with unrelenting bone pain and resultant immobility. As a result, VCFs may severely diminish quality of life, compromise pulmonary function, increase the risk of developing deep vein thrombosis and pressure ulcers, interrupt sleep, increase fatigue, exacerbate emotional distress, produce analgesic-related constipation, and increase the risk of spinal cord compression.5,7 In addition, VCFs may lead to the development of kyphosis, a spinal deformity. This particular deformity is associated with numerous complications including anorexia, due to compression of the abdominal contents; decreased activity tolerance, due to compromised lung capacity; and further spinal deformity, due to an altered center of gravity.4
VERTEBRAL FRACTURE REPAIR
Vertebral pain is the most prevalent symptom of myelomatous bone disease. Systemic treatment of the disease itself is the most effective means of relieving vertebral pain, as it may slow the process of further bone destruction. Systemic treatment may be accompanied by various adjunctive interventions such as analgesic and bisphosphonate medications, targeted radiation, and open spinal surgery. These interventions are critical components of the treatment plan and may be indicated at some point in the disease trajectory. However, when used in isolation of other interventions, these treatments alone will not effectively restore the strength of collapsed vertebrae, nor will they provide immediate pain relief. Satisfactory pain management and improved spinal integrity are best achieved through multidisciplinary collaboration. A relatively new and minimally invasive surgical procedure used to repair vertebral fractures is percutaneous vertebroplasty.
Percutaneous vertebroplasty is a minimally invasive vertebral augmentation procedure for the management of painful vertebral compression fractures. The successful use of this procedure was first documented in France in the mid-1980s, where it was used to treat painful vertebral collapses secondary to hemangiomas and osteoporosis.3,7 Since then, the procedure has also shown promise for patients with painful myelomatous vertebral compression fractures. Percutaneous vertebroplasty is a relatively short procedure (15 to 20 minutes per vertebrae) with the aim to provide nearly immediate pain palliation as well as restoration of vertebral function.5,7 The pain relief achieved through this procedure can improve functional abilities and enhance overall quality of life.1,3,7,8 Most importantly, the rapid results of this procedure allow the continuation of systemic treatment, which is the key to controlling the progressive nature of multiple myeloma.7
The palliative vertebroplasty procedure is performed by an interventional radiologist, orthopedic surgeon, or neurosurgeon and is usually done under local anesthetic with the patient in the prone position.5,6 In general, the portions of the spine that can be safely accessed via the percutaneous route are vertebrae T3 to L5. Experienced operators can safely perform this procedure up to the cervical area.4 Once the targeted vertebrae are confirmed, a small cutaneous dorsal incision is required.2 Under continuous fluoroscopic guidance, an 11- or 13-gauge trocar is placed in the damaged vertebral body via percutaneous extrapedicular or transpedicular approach.2,5-7 The needle is advanced into the anterior third of the fractured vertebral body until it reaches midline.5 At this position, a viscous cementlike mixture consisting of polymethylmethacrylate (PMMA) powder, barium sulfate powder, and an antibiotic powder for infection prophylaxis is then inserted into the vertebral body.5 The PMMA functions to restore the compressive strength of the vertebrae with the ultimate goal of alleviating intractable local pain and preventing a compression fracture.5
After the procedure, the incision is sutured, and the patient requires strict bed rest for 1 to 2 hours to allow cement polymerization.9 Further imaging must be completed to identify postvertebroplasty artifacts before the patient can be discharged home. This postoperative CT scan is intended to rule out cement extravasation and becomes the new baseline for comparison with subsequent images.8 The short procedure is typically a day surgery, with same-day discharge.