Balloon Kyphoplasty

Background

Vertebral compression fractures (VCFs) are a common type of fracture occurring in the body of the vertebra due osteoporosis, myeloma, trauma or metastatic deposits. They lead to chronic pain, nerve compression and spinal deformity. Progressive spinal fractures lead to impaired health-related quality of life, restricted lung capacity, loss of appetite, loss of independence, and mental status change due to pain and the use of medications. Osteoporotic VCFs are also known to be associated with an increased mortality rate.

Of patients with osteoporosis VCFs have a prevalence rate of 23.5% in women and a rate of 21.5% in men. The most frequently fractured locations are the lower thoracic and upper lumbar vertebrae. The cervical vertebrae and the upper third or the thorax are rarely involved.

Traditionally bed rest, medication, and bracing are used to treat painful VCFs. However anti-inflammatory and narcotic medications are often poorly tolerated by the elderly and may harm the gastrointestinal tract. Bed rest and inactivity may accelerate bone loss, and bracing may restrict diaphragmatic movement. Furthermore, medical treatment does not treat the fracture in a way that ameliorates the pain and spinal deformity.

Prior to the introduction of cement techniques, the only alternative treatment for VCFs, was open surgical decompression and stabilisation of the fractured vertebrae with insertion of metal implants. However, because of the poor quality of osteoporotic bone, surgical fixation will often fail. In addition these are major procedures, poorly tolerated in the elderly and with long recovery times. Thus these procedures have generally been limited to cases where there is concurrent spinal instability, or neurological deficit from spinal cord compression.

The Technology

Balloon kyphoplasty (BKP) is a technique of fracture reduction and (internal) fixation performed minimally-invasively. The fracture reduction is achieved with a balloon that is tough enough to compress the bone marrow, and internal fixation involves the injection of cement. Balloon kyphoplasty has been available since the late 1990s and up to 3 levels can be treated in a single session. The procedure is usually performed under general anaesthesia assisted by x-ray fluoroscopy.

In the procedure the patient is laid prone (face down) on the operating table and a needle introduced on either side of the vertebral body, via the transpedicular or extrapedicular route, followed by the insertion of inflatable balloons. These are filled with contrast medium for x-ray visualisation. The balloons are inflated simultaneously in order to obtain 'en masse' reduction of the fracture. This inflation compresses the cancellous bone of the vertebral body and can re-align the endplates. The resulting cavity is filled with viscous polymethylmethacrylate (PMMA) cement at low pressure under x-ray screening. The PMMA infiltrates the bone widely, hardens and stabilises the fracture.

The goals of balloon kyphoplasty are restoration of vertebral height, spinal stabilisation and pain relief.

Clinical efficacy

In published studies BKP consistently improved patients' level of pain and physical functioning in the period immediately following the procedure, sustained for up to 24-months, compared to conventional medical care. Three studies, namely Grafe et al, Weiskoff et al and Grohs et al, reported statistically significant improvements in pain and functional capacity with balloon kyphoplasty.

The later FREE study (Wardlaw W, Cummings SR, Van Meirhaeghe J, et al. Efficacy and safety of balloon kyphoplasty compared with non-surgical care for vertebral compression fracture (FREE): a randomised controlled trial. Lancet. 2009; Vol 373. Published on www.thelancet.com on February 24, 2009.) has confirmed the effectiveness of BKP in the first Level 1 randomised controlled study undertaken.

Pain Scores

With respect to visual analogue scores (VAS) the analysis of 9 studies indicates that kyphoplasty yields a mean score reduction of 4.70 points (95% CI: 4.59 - 4.78) and a median reduction of 4.7. The comparison between post- and pre-kyphoplasty values shows statistically significant differences in both measures. Similar results are obtained in the comparisons made between the scores at the end of the follow-up period and the baseline data.

Functional capacity

Functional capacity was assessed in three studies using differing outcome measures - Oswestry Disability Score (Coumans et al 2003), Index of Back Function (Garfin et al 2003) and physical activity (Ledlie et al 2003). A statistically significant improvement in functional capacity following balloon kyphoplasty was observed across all these studies.

Restoration in vertebral height and kyphotic angle

All studies reported an improvement in vertebral height following balloon kyphoplasty (Darius et al, 2003, Dudeney et al, 2002 Garfin, 2003; Hillmeier et al, 2003; Ledlie et al, 2003; Lieberman et al, 2001; Theodorou et al, 2002). Kyphotic angle was also reported to be reduced with balloon kyphoplasty, across the three studies. The average pre-post improvement in kyphotic angle ranged from a mean 4.30 to a mean of 9.90 (Darius et al 2003, Philips et al 2003, Theodorou et al 2002) up to 6-months post procedure.

Quality of Life

SF-36 (generic QoL)

In four studies using the widely accepted short-form 36 (SF-36) (Coumans et al 2003v, Dudeney et al 2002vii, Garfin et al 2003viii, Lieberman et al 2001xii) a statistically significant improvement in all quality of life sub-domains was found, for up to 2-years following balloon kyphoplasty. The pooled mean improvement in SF-36 sub-domain scores ranged from 14 to 34 points (on a 100 point scale).

Patient Satisfaction

A high level of patient safisfaction was reported following balloon kyphoplasty. Garfin and colleagues (2003) reported a median VAS satisfaction score of 17.5 at 24-month follow up and all previous time points. Philips et al (2003) reported that 31% of patients were satisfied (5-8 on a 0-10 scale) and 65.5% were very satisfied (9-10 on a 0-10 scale) with balloon kyphoplasty.

Clinical Safety

Cement leakages

Radiologically visible cement leakage was reported at a rate of 6.5 % (cf up to 40% of vertebrae treated with vertebroplasty). There were no reports of leakages with balloon kyphoplasty that were linked with adverse sequelae, such as neurologic injury or pulmonary embolism.

Adverse events

Across the 5 major studies, the authors reported no 'serious' operative or post-operative balloon kyphoplasty adverse events. Komp et al (2003) reported one death in 21 patients, unrelated to the kyphoplasty procedure. Fourney and colleagues (2003) reported one patient (out of 15) experienced an exacerbation of heart failure during the balloon kyphoplasty procedure and the FREE study revealed a 3% risk of complications including pneumonia, stroke and heart failure in a large cohort with mean age of 75yrs.

Key Patient Benefits

  • Reduced length of stay from mean 5 days to 1 day
  • Reduced rate of complications at 0.5% per procedure
  • Immediate pain relief
  • Significant improvement in Quality of Life
  • Correction of spinal deformity (kyphotic angle and spinal realignment)
  • Height restoration of the vertebral body
  • Reduction in incidence of new (adjacent) vertebral fractures