Kyphoplasty in osteoporotic vertebral compression fractures - Guidelines and technical considerations
© Robinson et al; licensee BioMed Central Ltd. 2011
Received: 5 February 2011
Accepted: 19 August 2011
Published: 19 August 2011
Osteoporotic vertebral compression fractures are a menace to the elderly generation causing diminished quality of life due to pain and deformity. At first, conservative treatment still is the method of choice. In case of resulting deformity, sintering and persistent pain vertebral cement augmentation techniques today are widely used. Open correction of resulting deformity by different types of osteotomies addresses sagittal balance, but has comparably high morbidity.
Besides conventional vertebral cement augmentation techniques balloon kyphoplasty has become a popular tool to address painful thoracic and lumbar compression fractures. It showed improved pain reduction and lower complication rates compared to standard vertebroplasty. Interestingly the results of two placebo-controlled vertebroplasty studies question the value of cement augmentation, if compared to a sham operation. Even though there exists now favourable data for kyphoplasty from one randomised controlled trial, the absence of a sham group leaves the placebo effect unaddressed. Technically kyphoplasty can be performed with a transpedicular or extrapedicular access. Polymethyl methacrylate (PMMA)-cement should be favoured, since calcium phosphate cement showed inferior biomechanical properties and less effect on pain reduction especially in less stable burst fractures. Common complications of kyphoplasty are cement leakage and adjacent segment fractures. Rare complications are toxic PMMA-monomer reactions, cement embolisation, and infection.
Osteoporosis and pathological osteoporotic fractures are common findings in the elderly population. The age-standardised annual incidence of vertebral compression fractures (VCF) is 10.7/1000 in women and 5.7/1000 in men, increasing markedly with age . At the age of 75 to 79 the annual incidence was 29.3/1000 in women and 13.6/1000 in men. Due to the continued aging of our population, VCF represent a major cause of disability and are a burden to the national healthcare budgets . Non-surgical management with pain control and physical therapy-assisted mobilization has for a long time been the only treatment option in VCF. Unfortunatelty a great number of patients remain functionally impaired after VCF, and some of them are severely handicapped due to chronic back pain . The functional and physical consequences of VCF lead to anxiety, depression, and have devastating impact on interpersonal relationships and social roles . It is therefore no surprise that untreated VCF contribute significantly to shorter life-expectancy both in women (mortality ratio 1.66, p < 0.01) and even greater in men (mortality ratio 2.38, p < 0.0001) within one year after onset of symptoms .
Indications for cement augmentation
while medical therapy of osteoporosis improves dramatically, the restoration of quality of life is still a major issue in VCF treatment. Osteoporotic kyphotic compression fractures often lead to a anterior shift of the sagittal plumb line and increased load of the anterior vertebral column, which may cause further compression fractures . This cascade of sequential compression fractures is eventually causing the typical hump of the elderly, with significant thoracic kyphosis and low pelvic incidence, forcing the patient to bend hips and knees to maintain sagittal balance .
Galibert et al  presented the first cases of successful vertebral augmentation by intravertebral injection (vertebroplasty) of polymethyl methacrylate (PMMA) in patients with vertebral haemagiomas. Later, vertebroplasty was successfully introduced for the management of osteoporotic compression fractures . The primary goal of vertebroplasty is pain relief by stabilization of the VCF, improving indirectly pulmonary function and patient quality of life . The biomechanical understanding of increasing anterior column load with progressing kyphosis leading to subsequent VCF established the basic rationale for kyphoplasty. With this technique, partial reduction of VCF is possible by transpedicular intracorporal balloon expansion and retention by PMMA cement augmentation [11, 12]. The results of one multicenter randomised controlled trial found shortened and improved functional recovery after kyphoplasty with a low rate of complications if compared to non-surgical treatment .
Despite the advances in percutaneous augmentation techniques the conservative medical therapy cannot be replaced. VCF without initial kyphosis, no consecutive sintering and a satisfactory and quick response to conservative treatment should be treated conservatively. Furthermore, since lack of reimbursement in most countries kyphoplasty causes an economic burden, many patients are not willing to take. Beyond that, it has to me emphasised, that it remains unclear whether the benefits of kyphoplasty outweigh its complications.
Guidelines for indications and contraindications for kyphoplasty
Indications for kyphoplasty
- Radiologically confirmed fresh compression fracture (AO type A1) (MRI shows oedema or X-ray/CT-scan proven fracture not older than 3 months)
- Failure of 2 - 6 weeks of conservative treatment including pain medication and physiotherapy (Pain on visual analogous scale (VAS) above 4 of 10)
Contraindications for kyphoplasty
- Burst-fractures (in some A3.1-fractures possible)
- Flexion-/distraction and rotational injuries (AO type B and C)
- Medical contraindications (bleeding disorders, sepsis, etc)
Due to the increased demand in cement augmentation techniques, procedures similar to kyphoplasty have been developed. One competitor is Vesselplasty® (A-Spine), where a porous balloon is inflated within the fractured vertebral body and filled with cement without removing the balloon, thus reducing the risk of cement leakage . Another new product is the Sky® bone expander (Disc-O-Tech), an expandable polymer bone tamp abandoning the use of cement, which had favourable results in clinical case series . Then there is the StaXx® FX system (Spine Wave) where a VCF is reduced percutaneously by gradual insertion of stacked PEEK-chips into the vertebral body to reduce and stabilise the fracture .
Indications for combined cement augmentation and posterior instrumentation
Lately kyphoplasty has been discussed as an alternative therapy even of burst fractures in elderly patients. This is especially true in case of AO type A3.1 fractures, where it could be applied instead of a posterior-only or 360 degrees stabilisation . In many of these cases further sintering of the fractured vertebra with posterior dislocation of an instable fragment with spinal stenosis is a feared complication [26, 27]. Thus several surgeons perform posterior instrumentation of the adjacent vertebrae to protect the posterior wall and to improve the sagittal profile . This can be done using percutaneous posterior instrumentation or with a conventional open technique [28–30]. Possible disadvantages of this technique are due to segmental fusion an increased load of the adjacent segments with degeneration, and possible implant loosening with loss of correction due to low bone quality. Cement augmentation of the implanted pedicle screws can reduce the complication rate regarding the latter mentioned problem .
Limitations of kyphoplasty and indications for open reduction and stabilisation
If multiple VCF lead to kyphosis with fixed sagittal imbalance, cement augmentation will address the fracture pain but not global imbalance. Major spinal imbalance can be a cause of significant functional disability leading to reduced quality of life. Increased kyphosis may additionally cause subsequent VCF due to an increased anterior load . The anterior location of the sagittal plumb line in fixed sagittal imbalance will lead to falls with possible further fractures and morbidity. Therefore the indication for correction of global sagittal imbalance may be given in severe cases. As both open and closing wedge procedures are associated with complications leading to disabling morbidity surgeon are often hesitant to perform these operations in patients with multiple comorbidities . Due to the osteopenic bone quality often long instrumentations are required. Unfortunately these an increased risk of adjacent VCF and pedicle fractures . With regard to open sagittal corrections there is growing evidence that the posterior-only pedicle subtraction osteotomy is superior to multiple Smith-Petersen osteotomies, allowing greater correction with lesser operation time [35, 36].
Operation technique of kyphoplasty
Percutaneous bilateral transpedicular kyphoplasty
Percutaneous unilateral extrapedicular kyphoplasty
Open unilateral interlaminary kyphoplasty
Open interlaminary kyphoplasty should be reserved for cases where an open approach has to be performed to decompress neurological structures, and the spinal canal has to be accessed anyway . After open decompression the dural sac is retracted medially and the posterior wall of the fractured vertebra exposed. Now kyphoplasty can be performed with a single balloon positioned under fluoroscopical guidance in the centre of the vertebral body. After kyphoplasty the spinal canal has to be investigated for cement leakage. This method must be restricted to levels below the conus medullaris to avoid myelopathy due to manipulation within the spinal canal.
Open anterior kyphoplasty
In rare cases kyphoplasty may be performed using an anterior access, too . Through a minimally-invasive anterior access the biopsy needle may be placed directly on the anterior wall of the fractured vertebra and a single balloon be placed into the vertebral body. Then under fluoroscopical control the fracture is reduced and cement is applied.
Operation room setup
Both general an local anesthesia have been successfully applied for the procedure , but many surgeons favour general anestesia allowing closed reduction in a relaxed patient. By patient positioning only, more than 70% of vertebral height restoration can be achieved. Placing the patient in prone position lordosating the fractured segment by pillows or by bending the table will lead to reduction of the fracture with ligamentotaxis .
As in most percutaneus surgical techniques implant positioning and accuracy is controlled with fluoroscopic image intensifiers. Correct positioning of the image intensifier will lead to much lesser radiation dose for the surgeon. Placement of x-ray tube in the image intensifier on the opposite side of the surgeon will causes up to 10 times less radiation exposure .
Balloon placement accuracy can be significantly improved and the radiation exposure during kyphoplasty can be reduced by as much as 76%, if computer-assisted fluoroscopic navigation is applied [44, 45]. While relying on the navigator during the transpedicular balloon placement, balloon inflation and cement injection have to be performed under fluoroscopic control to minimise endplate fractures and cement leakage.
An eggshell-procedure may avoid cement leakage in VCF suscpicious for endplate or posterior wall damage . After reduction with the kyphoplasty balloon a small amount of doughy cement is injected into the cavity, and then the balloon reinserted and reinflated. Once the cement hardens the cavity can be filled with cement within the "eggshell", preventing cement leakage.
Choice of cement
Most vertebroplasty and kyphoplasty procedures have been performed using polymethylmethacrylate (PMMA) cement to augment the fractured vertebra. The increasing availability of injectable calcium phosphate (CaP) cement led to its application in the augmentation of compression fractures as an alternative to PMMA. Advantages are high biocompatibility, no systemic toxic monomers, osteoinductive capacity, and close to isothermal cristallinisation. Disadvantages are besides less clinical long-term experience, lesser compressive strength than PMMA , and the risk of early resorption, leading to defects prone to re-fractures [48–50]. The available data does not encourage the clinical use of CaP-cement in burst-fractures, flexion-distraction injuries, or rotational instable fractures [48, 51].
Results and complications of kyphoplasty
Overview on comparative clinical trials of kyphoplasty
Level of evidence
Control n (levels)
Kyphoplasty n (levels)
Weisskopf et al. 
Improvement in VAS (p < 0.001) Reduced days in hospital (p < 0.01)
Fourney et al. 
No significant differences in VAS and ODI Improvement of kyphosis with kyphoplasty (p < 0.01)
Komp et al. 
Improvement of VAS and ODI with kyophoplasty (p < 0.01)
Kasperk et al 
Improvement of VAS (p < 0.01) and improvement of kyphosis (p < 0.001) with kyphoplasty
Grohs et al. 
No significant difference in ODI, but improvement of VAS with kyphoplasty (p < 0.05). No significant improvement of kyphosis
Masala et al. 
No significant difference in VAS.
Pflugmacher et al 
No significant difference in VAS and ODI. Improvement of kyphosis with kyphoplasty (p < 0.05)
De Negri et al. 
No significant difference in VAS and ODI.
Zhou et al. 
No significant differences in VAS, operation time and blood loss. Improved vertebral height restoration with kyphoplasty (p < 0.01).
Wardlaw et al. 
Significant improvement in EQ-5D (p < 0.05), RMDQ (p < 0.001) VAS (p < 0.0001).
Schmelzer-Schmied et al. 
Significant greater improvement of VAS (p < 0.05) with kyphoplasty, which was lost after 3 months, and vertebral height preservation after 12 months (p < 0.01)
Schofer et al. 
No significant differences in VAS and SF-36. Greater improvement of kyphotic angle with kyphoplasty (p < 0.001)
Li X et al 
No significant differences in VAS and ODI. Significantly greater improvement of kyphotic angle with kyphoplasty (p < 0.01)
The comprehensive meta-analysis of Lee et al  summarized all published kyphoplasty complications. Cement leakages occurred in 14% of all cases, but only 0.01% were symptomatic. New vertebral fractures occurred in 17%. Taylor et al  found in their metaanalysis furthermore spinal stenosis with spinal cord compression occurred 0.16% of all cases. Radiculopathy was found in 0.17% of all cases. Furthermore there are anecdotal reports of infections after kyphoplasty . The overall mortality was 4.4%, and the perioperative mortality was 0.13% .
Kyphoplasty is - in the hands of an experienced spine surgeon or radiological interventionalist - an effective tool to treat pain caused by thoracolumbar vertebral compression fractures, but the severity of pulmonary PMMA cement embolism and the urgent need of immediate decompression in relevant spinal stenosis after cement leakage, require an anaesthesiologist and a spinal surgeon on call. The complication rate of kyphoplasty is dramatically lower than in alternative open instrumented procedures, and the immediate pain reduction is significantly greater in kyphoplasty compared to conservative treatment. Therefore its application remains a pillar in VCF treatment.
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