2 The procedure

2.1 Indications

2.1.1 Vertebral compression fractures are one of the most common types of osteoporotic fracture. Osteoporotic fractures are common in the elderly and particularly in postmenopausal women, but they can also be associated with other factors such as chronic steroid usage. Other causes of vertebral compression fracture include malignancy in the vertebrae or, more rarely, haemangioma.

2.1.2 Pain is the most common symptom in patients with vertebral compression fractures. Fractures can also cause progressive spinal deformity with abnormal curvature (kyphosis). This can lead to increased risk of further fracture at adjacent levels and progressive malalignment, deformity and pain. There is also an increased risk of falls.

2.1.3 Conventional treatment for vertebral compression fractures is focused on the alleviation of symptoms with analgesic medication and spinal support. The majority of patients become symptom free through these measures and surgery is rarely indicated.

2.1.4 Surgery may be considered in patients whose condition is refractory to medical therapy and in whom there is continued vertebral collapse and severe pain. Recently there has been increased interest in minimally invasive procedures, including balloon kyphoplasty and vertebroplasty.

2.2 Outline of the procedure

2.2.1 Balloon kyphoplasty is performed under local or general anaesthesia assisted by fluoroscopy. One or more levels of the spine can be treated in one session.

2.2.2 The fractured vertebra is accessed through a small incision in the patient's back. A hand drill is used to create a channel through which one or two balloon-like devices (inflatable bone tamps) can be inserted into the medullary space. The inflatable tamp is positioned in the vertebral body and filled with a radiopaque contrast medium for visualisation. The balloon is slowly inflated until the normal height of the vertebral body is restored or the balloon reaches its maximum volume. The balloon is then deflated and the cavity created filled with cement (typically polymethylmethacrylate, PMMA) at a low pressure.

2.3 Efficacy

2.3.1 Three non-randomised studies were reviewed: two compared balloon kyphoplasty with conventional medical care (physical and analgesic therapy) and one compared the procedure with vertebroplasty. All three studies found that patients who had undergone balloon kyphoplasty had improved pain scores compared with the control group at a maximum follow-up of 24 months.

2.3.2 In two non-randomised controlled studies, physical function following balloon kyphoplasty, as measured by the European Vertebral Osteoporosis Study Group questionnaire or Oswestry Disability Index (ODI), was shown to be significantly improved from baseline at 12 months. However, in one of these trials physical function (ODI) at 2 years was not found to be significantly different from preoperative values in either the balloon kyphoplasty group (61% vs 56%) or the vertebroplasty group (61% vs 52%).

2.3.3 In a study of 222 patients (360 procedures), a greater than 20% restoration of lost vertebral height was achieved in 63% and 69% of fractures at the anterior and midline, respectively, and the kyphosis angle decreased from 22° to 15°. In a study comparing balloon kyphoplasty with conventional medical care, midline vertebral body height was significantly increased in the balloon kyphoplasty group compared with that at baseline and at 12 months was significantly greater than in the controls (67% vs 56%). For more details, refer to the Sources of evidence.

2.3.4 The Specialist Advisors expressed uncertainties about whether the improvements following balloon kyphoplasty (reduced pain and height restoration) are maintained in the long term.

2.4 Safety

2.4.1 The most commonly reported complications following balloon kyphoplasty were cement leaks and new fractures. One study of 360 procedures in 222 patients reported 38 cement leaks (11% of procedures), with one resulting in an episode of radiculopathy (the patient recovered with selective nerve block and rehabilitation). In another study of 192 procedures in 102 patients, cement leaks were reported from eight vertebral bodies (7%), all of which were asymptomatic.

2.4.2 In one study of 115 osteoporotic patients (225 procedures), 26 patients (23%) developed a post-procedure fracture. In the non-randomised controlled study comparing balloon kyphoplasty to standard medical care, seven new fractures were observed in 7/40 (18%) patients in the balloon kyphoplasty group, compared with 11 fractures in 10/20 (50%) patients in the control group. In another non-randomised controlled study (28 patients undergoing balloon kyphoplasty, 35 fractures), six fractures to adjacent vertebrae were observed within 4 months from the procedure.

2.4.3 Other reported adverse events during or after balloon kyphoplasty included balloon rupture (two cases), motor deficits caused by faulty puncture (one case) and epidural bleeding (one case).

2.4.4 In a review of complications reported to the US Food and Drug Administration (Center for Devices and Radiological Health), there were 33 major complications in patients (denominator estimated at between 40,000 and 60,000 procedures) following balloon kyphoplasty. These included one death; five cases of permanent paralysis, radiculopathy, paraesthesia or loss of motor function; and 13 cases of canal intrusion or cord compression. For more details, refer to the Sources of evidence.

2.4.5 The Specialist Advisors listed cement leakage as the most common complication following balloon kyphoplasty. They also listed infection, allergy and spinal cord or nerve root injury caused by incorrect needle placement as potential complications.