Vertebral Augmentation: What Is the Role of Vertebroplasty and Kyphoplasty?

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Chapter 3 Vertebral Augmentation: What Is the Role of Vertebroplasty and Kyphoplasty?

ISADOR. LIEBERMAN, MD, MBA, FRCS, KRZYSZTOF. SIEMIONOW, MD

Osteoporosis is a disorder characterized by decre-ased bone density, disruption of trabecular architecture, and increased susceptibility to fractures. There are approximately 700,000 vertebral body compression fractures (VCFs) occur in the United States each year.¹ Approximately 70,000 of those result in hospitalization, with an average hospital stay per patient of 8 days.² The lifetime risk for a clinically evident vertebral fracture among postmenopausal white women older than 50 years has been estimated at about 16%, whereas the lifetime risk in white men is about 5%.³ Clinical evidence shows that, if untreated, up to 20% of patients with a prior VCF are likely to have an additional VCF within the same year.⁴ The diagnosis of a single osteoporotic VCF increases the risk for subsequent fractures by a factor of 5. Patient population studies suggest an increased mortality rate in patients with osteoporotic VCFs that correlates with the number of fractured vertebrae.¹ A benign natural history has long been assumed for osteoporotic VCFs, but up to 30% of those who are symptomatic and seek treatment do not respond adequately to nonsurgical treatment.^5,⁶

VERTEBRAL AUGMENTATION

Currently, vertebral augmentation can be performed using either a vertebroplasty or kyphoplasty technique. They are both used in the treatment of osteoporotic vertebral fractures, and these methods should not be considered mutually exclusive. They are both minimally invasive procedures used in the treatment of symptomatic osteoporotic VCFs. The objective of any vertebral augmentation technique is to restore strength and stiffness to the fractured vertebral body with the injection of cement.

Historically, “percutaneous vertebroplasty” was conceived in France in 1984 to reduce pain from symptomatic vertebral hemangiomas.⁷ A cervical vertebra was injected with acrylic cement during open surgery to strengthen the vertebral body. An analgesic effect was noted, and indications for the technique expanded to include both neoplastic disease and osteoporotic compression fractures through a percutaneous insertion of cannulas into the vertebral body, through which cement was injected.

The “kyphoplasty” technique was developed later in 1997; it is a minimally invasive technique that helps restore vertebral body height before cement augmentation.⁸ It involves inserting inflatable bone tamps, through percutaneously placed cannulas, into the vertebral body under fluoroscopic guidance. Once inflated, the bone tamps push up on the end plates, helping to reduce the loss of vertebral body height while creating a cavity for the bone cement.

The traditional indications for vertebral augmentation are progressive collapse of a vertebral body and intractable pain. Either a transpedicular or extrapedicular approach is used to reach the vertebral body. Contraindications to vertebral augmentation are systemic pathology such as sepsis, prolonged bleeding times, or cardiopulmonary pathology, which would preclude the safe completion of the procedure. Other relative contraindications include patients presenting with neurological signs or symptoms, nonosteolytic infiltrative spinal metastases, vertebral height collapse of more than 60%, burst fractures, or vertebral bodies with deficient posterior cortices ^9,¹⁰ (Tables 3-1 and 3-2).

TABLE 3-1 Efficacy of Kyphoplasty in Reducing Pain in Osteoporotic Vertebral Compression Fracture

TABLE 3-2 Efficacy of Vertebroplasty in Reducing Pain in Osteoporotic Vertebral Compression Fractures

REVIEW OF THE LITERATURE

A review of Ovid and PubMed conducted in April 2007 using the search terms “kyphoplasty,” “vertebroplasty,” and “outcomes” revealed 722 vertebroplasty-related articles and 250 kyphoplasty-related articles. Of that group, 152 articles included both techniques. Most balloon kyphoplasty and vertebroplasty studies are grade 4, single-center, and single-arm studies of a prospective or retrospective nature.

Several reports with higher levels of evidence have been published. However, no blinded randomized trials have compared either technique against medical management. One was a multicenter prospective study of kyphoplasty.¹¹ Two were concurrently controlled prospective studies comparing kyphoplasty with nonsurgical management.^12,¹³ There were two concurrently controlled prospective studies,^14,¹⁵ and one nonconcurrently controlled study comparing vertebroplasty with nonsurgical management.¹⁶ Several studies compared kyphoplasty and vertebroplasty. However, most were nonconcurrent comparisons,¹⁷^–¹⁹and two were unclear.^20,²¹ Several meta-analyses compared kyphoplasty and vertebroplasty,²²^–²⁴ and there were also several meta-analyses of only kyphoplasty or only vertebroplasty.²⁵^–²⁸

SYSTEMATIC REVIEW OF VERTEBRAL AUGMENTATION OUTCOMES

Taylor et al ²³ performed a systematic review and metaregression to compare the efficacy and safety of balloon kyphoplasty and vertebroplasty for the treatment of VCFs, and to examine the prognostic factors that predict outcome. They found Level III evidence to support both balloon kyphoplasty and vertebroplasty as effective therapies in the management of patients with symptomatic osteoporotic VCFs refractory to conventional medical therapy. However, balloon kyphoplasty appeared to offer a better adverse event profile.

In a follow-up study, the authors concluded that in direct comparison with conventional medical management, patients undergoing kyphoplasty experienced superior improvements in pain, functionality, vertebral height, and kyphotic angle at least up to 3 years after the procedure. Reductions in pain with kyphoplasty appeared to be greatest in patients with newer fractures. The authors concluded that balloon kyphoplasty appeared to be more effective than medical management of osteoporotic VCFs and as least as effective as vertebroplasty.²⁶

Hulme ²² conducted a systematic review of 69 studies in the literature. The objective of the review was to evaluate the safety and efficacy of vertebroplasty and kyphoplasty using the data presented in published clinical studies, with respect to patient pain relief, restoration of mobility and vertebral body height, complication rate, and incidence of new adjacent vertebral fractures. A large proportion of subjects had some pain relief, including 87% with vertebroplasty and 92% with kyphoplasty. Vertebral height restoration was possible using kyphoplasty (average, 6.6 degrees) and for a subset of patients using vertebroplasty (average, 6.6 degrees). Cement leaks occurred for 41% and 9% of treated vertebrae for vertebroplasty and kyphoplasty, respectively. New fractures of adjacent vertebrae occurred for both procedures at rates that are greater than the general osteoporotic population but approximately equivalent to the general osteoporotic population that had a previous vertebral fracture. The authors concluded that the problem with stating definitively that vertebroplasty and kyphoplasty are safe and effective procedures was the lack of comparative, blinded, randomized, clinical trials.²²

In a review of cumulative data from 1279 vertebral bodies treated with kyphoplasty and 2729 vertebral bodies treated with vertebroplasty, Hadjipavlou and researchers ³⁰ found that the mean good to excellent pain response was reported by 90% of patients treated with vertebroplasty and 95.6% of patients treated with kyphoplasty. Vertebroplasty was associated with a 29% rate of cement leakage compared with 8.4% for kyphoplasty. The rate of epidural leakage was 10.7% with vertebroplasty and 1.2% for kyphoplasty. The series included VCF secondary to osteoporosis and tumor.²⁹

DOES VERTEBRAL AUGMENTATION IMPROVE OUTCOME IN PATIENTS WITH VERTEBRAL COMPRESSION FRACTURES?

In a prospective, nonrandomized, “intention-to-treat” study, Diamond and investigators ¹⁴ treated 126 consecutive patients (39 men and 87 women; ages 51–95 years) with acute osteoporotic vertebral fractures. Eighty-eight patients were treated by percutaneous vertebroplasty and 38 by conservative therapy. The primary outcome measure was change in the patients’ pain score and level of function at 24 hours, 6 weeks, 6 to 12 months, and 24 months after therapy. Secondary outcome measures were occurrence of new clinical or radiological vertebral fractures and survival at 2 years. Outcomes in patients treated with vertebroplasty showed greater reduction in visual analogue pain scores, faster return to normal function, and lower rates of hospitalization when compared with those treated conservatively (P < 0.001 for the comparison of all variables at 24 hours). Lower pain scores persisted in the group treated with vertebroplasty at 6 weeks (P < 0.001), but no differences between the two groups were evident at 12 and 24 months. In the group treated with vertebroplasty, compared with the control group, the rates of new vertebral fractures and death showed no significant difference. The authors concluded that the analgesic benefit of percutaneous vertebroplasty and the low complication rates suggest that cement augmentation is a useful therapy for acute painful osteoporotic vertebral fractures.¹⁴

Alvarez and colleagues ¹⁵ performed a prospective study consisting of 101 consecutive patients who underwent vertebroplasty and 27 patients who refused operative treatment and were managed conservatively. Patients who elected for vertebroplasty as a treatment of their fractures had significantly more pain and functional impairment before the procedure than the patients in the conservative group (P < 0.001). Vertebroplasty demonstrated a rapid and significant relief of pain and improved the quality of life.¹⁵

Majd and researchers ³⁰ prospectively followed 222 osteoporotic patients with 360 VCFs who were treated with kyphoplasty. Immediate pain relief was reported by 89% of patients at the first follow-up visit. One patient experienced postoperative pain as a result of radiculopathy related to leakage into the foramen. Sixty-nine percent of fractures exhibited restoration of lost vertebral height. Twelve percent (30/254) of the patients required additional kyphoplasty procedures to treat 36 symptomatic, new adjacent and remote fractures.³⁰

Studies comparing kyphoplasty with conventional medical treatment found that kyphoplasty consistently improved pain and physical function, with results sustained at 12 months.¹² In addition, the authors found that there were significantly fewer patients with new vertebral fractures of the thoracic and lumbar spine, after 12 months, in the kyphoplasty group than in the group treated medically. Another benefit of the kyphoplasty technique is the restoration of mobility. Garfin and investigators¹¹ demonstrated that elderly patients with VCFs had rapid, significant, and sustained improvements in back pain, back function, and quality of life after balloon kyphoplasty.

Khanna and colleagues ³¹ prospectively followed 155 patients with VCFs secondary to osteoporosis and 56 patients with malignant osteolysis for a mean 55.0 weeks after kyphoplasty. The average Owestry Disability Index score decreased by 12.6 points (P < 0.001) in the overall group, by 11.8 points (P < 0.001) at short-term follow-up, and by 8.6 points (P < 0.001) at long-term follow-up. All Health Survey Short Form-36 subscores except for general health and role-emotional showed statistically significant improvement from baseline values at the same time points. No statistically significant difference was found for functional outcome in the osteoporosis and multiple myeloma subgroups.³¹