Indications
Vertebral augmentation procedures are currently indicated for painful osteoporotic or osteolytic vertebral compression fractures refractory to conservative treatment.

There is as yet no data to support the prophylactic use of the procedure in at risk patients.

Absolute contraindications are cord compression, infection and coagulopathies. Relative ones are severe collapse which increases the technical difficulty of the procedure, posterior wall involvement, unstable fracture patterns and a radicular component to symptoms.

Epidemiology
In the US at any one time it is estimated that around 30 million people are at risk of an osteoporotic fracture, with a lifetime risk of 16% in females and 5% in males. Half of the 1.5 million osteoporotic fractures that occur annually are vertebral and one third of these become chronically painful.

There is a significant associated morbidity and mortality with restricted mobility, a 9% reduction in FVC per thoracic fracture and a susceptibility to further fractures because of the altered biomechanics.

Osteoporotic vertebral fractures are associated with a 23% age adjusted increase in mortality with a five year survival less than that associated with hip fracture.

Most people are treated conservatively with analgesics, bed rest and bracing, but a small percentage are left with persistent pain and limited mobility Although the cost of prolonged hospital stays is increasing, there have been no studies of the economic benefits of the procedure which should be limited to patients whose pain is refractory to more conservative treatment.

The Procedure
This procedure should only be undertaken when there are arrangements for good access to a spinal surgery service, and with prior discussion between a specialist multidisciplinary team that includes a radiologist and a spinal surgeon. In addition the procedure should only be performed by physicians who have received sufficient training to reach a suitable level of expertise in the procedure.

The aim of treatment, as with that of any fracture is to restore anatomy, restore stability, to reduce pain and to improve function.

Percutaneous cementoplasty may be performed under general anaesthetic or more commonly, using conscious sedation and local anaesthesia. A small incision is made and a 10 to 12 gauge trocar or needle, under fluoroscopic guidance, is passed into the bone being treated. The needle can be passed by either an extra pedicular or a transpedicular approach.

When performing kyphoplasty, prior to cement insertion inflatable bone tamps containing contrast for visualisation are inserted via each pedicle and inflated using a manometer with a digital pressure gauge. Each balloon is alternately filled in small increments until a pressure of approximately 150psi is reached or a satisfactory reduction is achieved, whichever comes first. The risks related to balloon failure are minimal because the pressure rapidly decays to zero and the IBT can be safely removed. Once appropriate volume and reduction have occurred, the balloons are deflated and removed. Because the bone is impacted and the patient prone without gravitational forces loading the spine, loss of reduction does not usually occur.

The cement is mixed with barium sulphate or other agent to enhance radio-opacity. The cement is allowed to thicken to the consistency of toothpaste, to lessen the risk of extra-osseous leakage upon injection. Visualisation of the cement during injection, via fluoroscopy (multi-plane), is essential to ensure safety, as every attempt should be made to avoid extra-osseous leakage of cement.

Results
Papers reporting the results of vertebroplasty are usually retrospective case series with small numbers. There does however seem to be evidence of reduced pain and improved function when used to treat osteoporotic fractures. Collating the literature, of over 400 procedures with greater than three years follow up, good pain relief is reported in between 70-90% with 74% having an improved quality of life.

In one series¹, there was a 91% decrease visual analogue score (VAS) pain score (compared to 73% in a control population treated conservatively), 8.3 day analgesia requirement (as compared to 62 days) and an improved kyphosis of 8 degrees (with an average 21 degree deterioration in the controls) at one year.

Longer term benefit is less clear. In a series of 50 patients², a significanty reduced VAS and Oswestry Disability index score (ODI) was seen at 1 year. However, others have found that the significant improvement in pain and function at 24 hours, does not persist beyond a few weeks.

In a prospective, non randomised two year trial versus conservative treatment³, of 126 patients treated with vertebroplasty, 25% required no analgesia at 24 hours and 60% had decreased pain scores at six weeks. However, there was no difference between the groups at 1 or 2 years. Also, no difference in refracture or death rates was seen.

In the two non-randomised controlled trials that had follow-up of 12 months or more, physical function following balloon kyphoplasty (as measured by the European

Vertebral Osteoporosis Study Group questionnaire (EVOI) or ODI) was shown to be significantly improved from baseline at 12 months.

However in one of these studies⁴ this difference was similar to the improvement in those receiving medical care (54.5 ± 3.04 versus 44.3±5.07) and in the second study⁵ physical function (ODI) at two years was not found to be significantly different from preoperative values in either the balloon kyphoplasty (61% vs 56%) or vertebroplasty group (61% vs 52%).

Vertebral height and kyphosis where measured was reported to be corrected in patients following balloon kyphoplasty. In a study of 222 patients (360 procedures)6, a greater than 20% restoration of lost vertebral height was achieved in 63% and 69% of fractures at the anterior and midline. The kyphosis angle also decreased from 22 to 15. In a study comparing kyphoplasty with conventional medical care4 midline vertebral body height was significantly increased in the kyphoplasty group compared with that at baseline and at 12 months was significantly greater than in the controls (66.7% vs 55.8%).

Complications
An overall complication rate of between 1- 5% is reported when vertebroplasty is used to treat osteoporotic fractures. Potential risks include infection (<0.5%), pulmonary embolus, radiculopathy and paralysis (1 case in literature). More frequent complications are the risk of adjacent vertebral body fracture and cement leakage.

Cement leakage is reported in between 34 and 67% of cases. Although usually clinically silent, it can cause radiculopathies, pulmonary embolus and cord compression. If leakage outside the bone is identified, the injection should be paused to allow the cement to harden and plug the leak, or the needle repositioned.

Refracture rates are around 20% in the untreated patient. One series⁷ has reported a refracture rate of 52% after vertebroplasty. This rate varies depending on the properties of the cement used. Calcium phosphates eg kyphos, whilst less manageable and initially less resistant with a 30 minute hardening time, resorbs and osteointegrates and causes less load on adjacent vertebrae.

Others have reported rates of between 11% and 18% after kyphoplasty. This suggests that kyphoplasty does not increase the risk of remote or adjacent level fractures compared to historic natural history reports.

NICE Guidelines
Guidelines for vertebroplasty were issued in 2003 and for kyphoplasty in 2006.

There was consensus that evidence on the safety and efficacy of percutaneous vertebroplasty appears adequate but that this procedure should only be undertaken by clinicians who have received adequate training to achieve an appropriate level of expertise.

The procedure should be limited to patients whose pain is refractory to more conservative treatment.

They reported on evidence suggesting improved pain scores in patients treated with kyphoplasty when compared to control patients treated with either conventional medical treatment or vertebroplasty although uncertainty was expressed that these improvements were maintained in the long term.

Treatment of Metastases
Most patients with bone lesions experience pain. Common interventions include analgesia often with narcotic drugs, bed rest and radiation therapy.

However, the pain relieving effect of the latter can be delayed for up to two weeks and the effect on bone reconstruction is partial and requires several weeks to develop. Also, some patient remain refractory to both pharmacological and radiation therapy. With prolonged survival and ongoing osteolytic bone loss, vertebral compression fractures are becoming more of a clinical and functional problem for these patients.

Particularly good results have been reported when vertebroplasty has been used to treat osteolytic compression fractures caused by multiple myeloma. The near fluid consistency of the tumour and the lytic nature of the bone create a cavity which is easy for the cement to fill. However, when used in the treatment of nonmyelomatous osteolytic collapse, the results remain very favourable.

When used to treat osteolytic compression fractures caused by multiple myeloma, significant improvement in SF-36 scores for bodily pain, physical function, vitality and social function was seen after kyphoplasty in 55 patients⁸. No complications were reported.

There are reports of the successful use of vertebral augmentation procedures to treat metastases from other tumours, including lung and breast. The effects of potential tumour dissemination, in what is already widespread disease, is not known.

Other Uses
Vertebroplasty has been used to supplement short segment posterior instrumentation (SSPI) in the treatment of burst fractures⁹.

Greater restoration of vertebral height was achieved and maintained at follow up in those supplemented with kyphoplasty compared to a control group with SSPI alone. No failures of instrumentation were seen (compared to a 22% failure rate in the control group), no significant extravasation and no increase in canal compromise.

Summary
Vertebral augmentation is a potential treatment option in patients with painful, progressive osteoporotic or osteolytic compression fractures. The procedure is relatively straight forward, with a low complication rate. However, it should only be performed by physicians who have received sufficient training as there is the potential for catastrophic complications. Early results suggest that it can be effective in restoring stability and reducing pain although longer term results are less clear cut and further follow up is required.

References

1. Nakano M, Hirano N, Ishihara H et al. (2006) Calcium phosphate cement-based vertebroplasty compared with conservative treatment for osteoporotic compression fractures: a matched case- control study. J Neurosurg Spine 4(2);110-117.
2. Prather H, Van Dillen L, Metzler J et al. (2006) Prospective measurement of function and pain in patients with non-neoplastic compression fractures treated with vertebroplasty. J Bone Joint Sur[A] 88(2);334-41.
3. Diamond T,Bryant C, Browne L et al. (2006) Clinical outcomes after acute osteoporotic vertebral fractures: a 2-year non- randomised trial comparing percutaneous vertebroplasty with conservative therapy. Med J Aust 184(3); 113-7.
4. Kasperk C, Hillmeier J, Noldge G et al. (2005) Treatment of painful vertebral fractures by kyphoplasty in patients with primary osteoporosis: a prospective nonrandomized controlled study. Journal of Bone & Mineral Research 20: 604-612.
5. Grohs JG, Matzner M, Trieb K et al. (2005) Minimal invasive stabilization of osteoporotic vertebral fractures: a prospective nonrandomized comparison of vertebroplasty and balloon kyphoplasty. Journal of Spinal Disorders & Techniques 18: 238- 242.
6. Majd ME, Farley S, and Holt RT. (2005) Preliminary outcomes and efficacy of the first 360 consecutive kyphoplasties for the treatment of painful osteoporotic vertebral compression fractures. Spine Journal: Official Journal of the North American Spine Society 5: 244-255.
7. Grados F, Depriester C, Cayrolle G et al. (2000) Long term observations of vertebral osteoporotic fractures treated by percutaneous vertebroplasty. Rheumatology 39:1410-1414.
8. Dudeney S, Leiberman I, Reinhardt M et al. (2002) Kyphoplasty in the treatment of osteolytic compression fractures as a result of multiple myeloma. J Clin Oncol 20:2382-2387.
9. Cho D, Lee W, Sheu P. (2003) Treatment of thoracolumbar burst fractures with polymethyl methacrylate vertebroplasty and short- segment pedicle screw fixation. Neurosurgery 53(6):1354-60.

previous - return to list  - next