Percutaneous polymethacrylate vertebroplasty.
Percutaneous vertebroplasty is a minimally invasive procedure that involves the injection of polymethacrylate (PMA) bone cement into the vertebral body lesion to relieve pain and provide strength and stability to the bone. (1-3)
The first percutaneous polymethacrylate vertebroplasty (PPV) was performed in 1984 by French radiologists for a hemangioma in a female patient. (4,5) Over the past few years the procedure has gained popularity in the treatment of osteoporotic compression fractures of the vertebrae when conventional treatment has proven inadequate. Of the patients who have undergone PPV for osteoporotic compression fractures, 70% to 95% have reported pain relief immediately or within 24 hours of the procedure). (3,6-9)
Osteoporosis is a skeletal disorder characterized by compromised bone strength that puts an individual at an increased risk of fracture. (10) (See Fig. 1.) A fracture can occur when force is applied to the weakened osteoporotic bone. Osteoporotic fractures represent a growing medical and socioeconomic problem in the United States. According to the National Osteoporosis Foundation, osteoporosis is a health threat for approximately 44 million Americans and 10 million individuals currently suffer from the disease. (11) Osteoporosis is responsible for more than 1.5 million fractures annually, of which 700 000 are of the vertebrae. (9,11) Although osteoporosis can be found in various areas of the bony skeleton this paper focuses on osteoporosis of the vertebrae.
[FIGURE 1 OMITTED]
Osteoporotic vertebral compression (see Fig. 2) fractures are a painful and debilitating condition that represent a significant cause of morbidity and mortality in the elderly. (3,6) Fractures often lead to pulmonary dysfunction, eating disorders and spinal kyphosis that has been shown to significantly reduce the patient's quality of life, physical function, mental health and survival. (4,5,10) The leading symptom associated with osteoporotic compression fractures is varying degrees of back pain, with a progressive loss of height and restricted physical activity. (11,12) The typical medical management of osteoporotic fractures, the use of analgesics, bed rest and external bracing, often fall short for many patients, leaving them with progressive kyphosis, persistent pain and functional disabilities. (5-7) PPV represents a new treatment alternative that reinforces and strengthens the compressed bone, often relieving the symptoms immediately.
[FIGURE 2 OMITTED]
Review of Literature
The results of 3 separate studies conducted in 1999 of pain due to osteoporotic vertebral compression fractures concluded that PPV was effective in reducing pain and improving the health status of patients. (13-15)
The Cortet study (13) followed 16 patients requiring 20 PPV procedures. The patients presented with pain due to osteoporotic vertebral compression fractures. The patients were evaluated at day 3, 30, 90 and 180. The study concluded that positive improvements in pain and health status were still evident 6 months after the procedure. (13)
Wenger and Markwalder (14) reported that of the 13 patients who presented with pain, all were pain free at the end of 6 and 12 weeks after undergoing PPV.
Gangi et al (15) performed 1 of the largest long-term studies to date, consisting of 105 patients. The final report indicated that 78% of the patients reported a reduction in pain for an average of 2.5 years following PPV treatment. (15)
In another long-term study, Grados et al (16) followed 25 patients for at least 15 months and assessed the long-term results with a follow-up questionnaire. Of the 23 patients who completed the questionnaire, 22 continued to experience diminished back pain. (16) Additionally, Zoraski et al (17) conducted a long-term study in which 54 PPV procedures were performed on 30 patients. The patients completed a follow-up questionnaire 15 to 18 months postprocedure. Of the questionnaires returned, 22 of 23 patients remained "satisfied with the outcome and believed that the procedure had provided durable pain relief." (17)
In another study performed by Amar et al, (5) 97 patients underwent 258 procedures. Follow-up was obtained for 81 of the 97 patients at 14.7 months post-treatment. (5) The results concluded that 74% of the patients believed the procedure had "significantly enhanced their quality of life" and 26% reported no change. No patient was worse after the procedure.
Jenson presented the results of a more recent study at the annual meeting of the American Society of Neuroradiology. The study consisted of 84 patients with 159 compression fractures. The results indicated that 50% of the patients returned to all previous activities of daily living without assistance and/or stopped analgesic use following vertebroplasty. (18)
Diagnosis of Osteoporosis
Osteoporosis is a silent disease; therefore, the patient does not present until a fracture occurs and then only if the patient develops severe pain, reduced mobility and physical function. (19) The diagnosis of vertebral compression fractures usually begins with plain film radiography, followed by a thorough history and physical examination to correlate the location of the pain with the level of the fracture and to exclude any neurologic deficit or myelopathy. (4,17)
Magnetic resonance (MR) or computed tomography (CT) imaging is frequently used to determine if the spinal canal is compromised, assess the integrity of the posterior wall of the vertebral body and exclude additional causes of back pain. (4,7) (See Figs. 3 and 4.) The majority of patients respond positively to traditional treatment of osteoporotic compression fractures. However, some fail to respond to conventional therapy; therefore, PPV is an alternative method to manage painful osteoporotic fractures.
[FIGURES 3-4 OMITTED]
PPV is a technique in which a PMA cement is injected into the compressed vertebra to stabilize the fracture. Many experts believe that pain relief is achieved through mechanical support and stability provided by the PMA cement. (1,4) But pain relief also may be attributed to other factors, such as nerve root damage resulting from the heat generated by the polymerization. (1,4,5,17)
PPV is not appropriate for all patients. As with all medical procedures, there are specific indications and contraindications that must be considered before performing PPV. (See Table 1.)
Vertebroplasty is typically performed under sterile conditions in a standard angiography suite in the radiology department. In some cases the procedure is performed under CT guidance. (2,15) A local anesthesia typically is administered using a small amount of a narcotic for pain and a sedative. General anesthesia may be used for patients who are unable to remain still for extended periods of time. (5,18) The patient is positioned prone on the procedure table. The patient's blood pressure, heart rate and oxygen saturation are continuously monitored by the attending staff. (5)
The area of the affected vertebra is prepared and draped using the aseptic technique. The patient is given an intravenous antibiotic for infection. Under fluoroscopic guidance, the entry site overlying the pedicle is localized. In most cases a unipedicular approach is used, although at times it may be necessary to use a bipedicular technique to achieve proper filling. (5)
The entry site is anesthetized locally with a solution of lidocaine and bupivacaine through the subcutaneous tissues down to the periosteum of the pedicle. (5,18) At this point, an 11-gauge bone biopsy needle with an access cannula is inserted through the skin and seated against the periosteum. (4-6,17) Under fluoroscopy, the needle is advanced through drilled holes in the pedicles (20) and into the interior of the collapsed vertebra until it reaches the anterior one third of the vertebral body. (5,20) (See Figs. 5, 6 and 7.) A nonionic contrast material is injected through the cannula to reduce the risk of intra-vertebral cement-related complications, such as pulmonary embolism or epidural compression. (3,5,21) If contrast leaks outside the vertebral body, it is recommended that filling be halted for 60 seconds (2) and the cannula repositioned before filling resumes. (3,6)
[FIGURES 5-7 OMITTED]
A polymer powder is mixed with an antibiotic and barium sulfate or tungsten powder for opacification. (2,18,21) The cement mixture is allowed to polymerize until it has a paste-like consistency. (2) The low-viscosity cement then is injected into the vertebral body by a high-pressure injector until the compressed vertebral body is 70% filled. (5) PPV stabilizes the compressed vertebrae, but it does not increase the vertebral height of the affected vertebral body. (3,5) (See Figs. 8 and 9.)
[FIGURES 8-9 OMITTED]
Following the PPV procedure, the needle is withdrawn and an external antibiotic and sterile dressing are placed over the puncture site. The patient is instructed to lie supine for approximately 1 to 2 hours to allow the cement to harden. After the cement hardens, most patients are able to stand and walk with minimal or no pain. (4,5,18)
The majority of complications are minor and transient and occur in approximately 1% to 3% of the patients. (4,9,18) Complications include:
* Hemorrhage at the site, rib or posterior vertebral fracture.
* Increased pain for several hours postprocedure.
* Nerve root irritation from heat generated by the acrylic bone cement.
* Cement leakage.
* Infection. (4,18)
Other complications include decompressive surgery to remove cement that has leaked from the vertebral body or to repair a fracture caused by the injection of the cement; however, these complications occur in less than 1% of the patients undergoing PPV. (4,5,18) Any resultant spinal cord or nerve root damage may require emergency surgical decompression, but neurological complications are uncommon. (22)
Cement leakage is the most common complication reported and occurs in approximately 65% of the patients who undergo PPV. (3,8) However, cement leakage does not generally lead to serious or lasting complications. (6) According to Gilula, (22) small amounts of perivertebral venous, paravertebral soft tissue and intradiscal leakages are of no clinical significance in the short term and midterm (2,6).
Gangi et al (6) states that the following elements are necessary to avert complications with PPV and improve the end result:
* Well-suited and appropriate patients.
* Adequate radiographic and fluoroscopic guidance to ensure proper needle placement.
* Proper stage of polymerization before injection to avoid leakage.
* Adequate operator training. (6)
Osteoporosis remains the most prevalent bone disease in adults in the United States despite recent advances in diagnosis and treatment) (19) With growing numbers of elderly and increasing life expectancy, the number of people with osteoporosis and the cost of treatment will continue to rise. Studies have shown the PPV procedure to significantly reduce pain, and most patients undergoing PPV are able to return to normal daily activities and eliminate or decrease use of analgesics. In a high percentage of cases, PPV may benefit patients who suffer from chronic pain due to osteoporotic vertebral compression fractures and who are unresponsive to traditional therapies. (3,6,9)
Most of the studies in the current literature have only small numbers of subjects with limited follow-up. Additionally, these have not been controlled studies that compare PPV with the standard medical therapy used to treat osteoporotic compressed vertebral fractures. Larger, more controlled studies should be conducted with continued patient tracking to determine if long-term data continue to show positive results.
Table 1 Indications and Contraindications for PPV (4,7,18,19) Indications Contraindications Fracture between 2 weeks Healed Fracture and 6 months old Fracture responding to Moderate to severe pain traditional treatment Failure to respond to Untreated coagulopathy traditional treatment Presence of sepsis Associated disabilities (walking) Significant spinal canal compromise Some pathologies (myeloma, metastases) Fracture older than 1 year Herniated disc >80% to 90% collapse of vertebral body Adjacent tumor Infection Hemangioma of vertebral body Osteomyelitis Spinal canal compromise of >20% Tumor extension into the epidural space
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(10.) NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy. Osteoporosis prevention, diagnosis, and therapy. JAMA. 2001;285(6):785-795.
(11.) National Osteoporosis Foundation. Available at www.not.org/osteoporosis/stats/htm. Accessed February, 2002.
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(15.) Gangi A, Dietemann JL, Guth S, Steib JP, Roy C. Computed tomography (CT) and fluoroscopy-guided vertebroplasty: results and complications in 187 patients. Seminars in Interventional Radiology. 1999;16:137-142.
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(19.) Rosier RN. Expanding the role of the orthopaedic surgeon in the treatment of osteoporosis. Clin Orthop. 2001;(385):5767.
(20.) Bai B, Jazrawi LM, Kummer FJ, Spivak JM. The use of an injectable, biodegradable calcium phosphate bone substitute for the prophylactic augmentation of osteoporotic vertebrae and the management of vertebral compression fractures. Spine. 1999;24(15):1521-1526.
(21.) Landi MK, Grand W, Moreland B. Vertebroplasty: perils and pitfalls [abstract of oral presentation]. Neurosurgery. 2000;47(2):526.
(22.) Gilula L.A. Percutaneous vertebroplasty safe for older patients. RSNA News. 2002;12(5).
Linda Lingar, M.Ed., R.T. (R)(M), is an associate professor in the department of radiologic technology at the University of Arkansas for Medical Sciences.
Reprint requests may be sent to the American Society of Radiologic Technologists, Communications Department, 15000 Central Ave. SE, Albuquerque, NM 87123-3917.
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|Title Annotation:||Peer Review|
|Date:||Nov 1, 2004|
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