Balloon Kyphoplasty for Osteoporosis: Technical Notes

Vertebral fractures are the most common fractures in osteoporosis and have significant impact on quality of life and survival rates, as well as carrying increased socioeconomic costs (Becker, S. 2008). Kyphotic deformity results from those fractures are associated with increased morbidity and mortality (Johnell, O.1996; Edidin AA, et.al. 2011). Balloon kyphoplasty is a minimally invasive procedure designed to restore vertebral body height, decreasing kyphosis, and also aims to achieve pain relief by stabilization of the fracture (Garfin SR. 2002) In 1987, Galibert et.al described percutaneous vertebroplasty as an alternative of conventional treatment of vertebral fracture (Galibert P et.al. 1987). The technique and the products used were developed until the description of balloon kyphoplasty in 1998 (Deramond, H . et. Al. 1998).


Introduction
Vertebral fractures are the most common fractures in osteoporosis and have significant impact on quality of life and survival rates, as well as carrying increased socioeconomic costs (Becker, S. 2008). Kyphotic deformity results from those fractures are associated with increased morbidity and mortality (Johnell, O.1996;Edidin AA, et.al. 2011). Balloon kyphoplasty is a minimally invasive procedure designed to restore vertebral body height, decreasing kyphosis, and also aims to achieve pain relief by stabilization of the fracture  In 1987, Galibert et.al described percutaneous vertebroplasty as an alternative of conventional treatment of vertebral fracture (Galibert P et.al. 1987). The technique and the products used were developed until the description of balloon kyphoplasty in 1998 (Deramond, H . et. Al. 1998).

Rational
Balloon Kyphoplasty is performed nowadays by spine surgeons as well as by interventional radiologist. This is certainly an effective treatment of osteoporotic compression fracture, but it's more and more used in traumatic and metastatic fractures (Voggenreiter, G (2005) ;Wardlaw D. et. al (2009) Most patients were treated for vertebral fracture involving a single level (Table 1). Fracture types are divided into four groups: Primary and secondary Osteoporosis, trauma and tumor (Table 2). For secondary osteoporosis, chronic steroid use is the main etiology.

Etiology
No Vertebral fracture is confirmed through careful correlation of the patient's history, clinical examination, and radiological findings on X-ray's, CT scan and MRI. The majority of vertebral osteoporotic compression fracture occurs at the thoracolumbar junction: 30 cases at Th12 level and 108 at L1 level (Table 3).
The duration between diagnosis of the fracture and the intervention was between 1 day and 90 days with a mean of 10 to 30 days ( The fractures treated are not chronic or occurred > 90 days.

Indication
Indications for balloon kyphoplasty are (Lieberman IH, et. al (2001); Taylor RS, et.al (2007)) : -Primary or secondary osteoporosis, multiple myeloma, or osteolytic metastatic tumors. -Painful fractures with a back pain score of 4 points or more on a 0-10 scale. And, not responding to conservative treatment for 6 weeks. -Adjacent vertebra of a fractured and treated one at the level of Th12 or L1 in severely osteoporotic patient, older than 75 years of age with good Karnofsky performance status score (>70). We found that, in 19 cases (7 L1 and 12 Th12 fracture), a fracture of Th12 vertebra occurred in case of previous balloon kyphoplasty on L1 at 18 months and vice versa.

Contra indication
Patients are excluded if they (Theodorou DJ, et. al (2002); Berlemann, U (2008)): -Are younger than 21 years of age -Have chronic fractures (estimated fracture age more than 3 months) - Have pedicular fracture, previous vertebroplasty of the same vertebra, neurological deficit, radicular pain, spinal cord compression, or canal narrowing -Are taking uninterruptible anticoagulation therapy -Have allergies to kyphoplasty materials or contraindications to MRI -Have dementia -Are unable to walk before fracture (walking aids were allowed) -Have vertebral fractures from primary bone tumours, osteoblastic metastases, or high energy trauma.

Hospitalization and follow up
In our institution, patients are admitted for 24 hours the same day of the procedure. In preop, the patient is asked to hold anti-platelets and other anti-coagulation for 5 days. Only LMWH can be tolerated up to 12 hours before the procedure. Post op, spinal cord X-ray of the operated region is done. The patient is ambulated with abdominal belt for 1 month. Usually, the patients had regular follow up at 1, 3 and 12 months.

Biomechanics of cement injection
Injection pressure and cement viscosity are the most important factors for injection. Studies show that the use of more viscous cement in association to lower injection pressure is advantageous for the regular spreading. For this purpose, a geometrically modified cannulas and high viscosity cement were developed to decrease injection pressure and reduce the risk of insufficient filling of vertebral body (Berlemann,U (2008); Phillips, FM (2003); Vaccaro, A (2003)).

Product used
Polymethylmethacrylate (PMMA) bone cement was the first used in balloon kyphoplasty. It consists of several ingredients that all have their importance. To site, PMMA is composed by methyl methacrylate, PMMA powder ,radio-opacifier, dibenzoyl peroxide, and other additives such as stabilizers, inhibitors, radical catchers, coloring agents and antibiotics (Berlemann,U (2008); Baroud G, Steffen T (2005); Bohner M, et.al (2003)). PMMA is an easy handled product. It has an adequate balance between high viscosity, which reduces extravasation risks, and low viscosity, which enables low injection forces (Baroud G, et.al (2004); Weißkopf, M, et.al (2008)). PMMA is allowed to cure for 3 to 5 minutes before injection to achieve a tooth paste viscosity. It needs 8 to 12 minutes in vivo to harden before removing injecting cannulas www.intechopen.com

Operative procedure
The level of the pedicle of the fractured vertebrae is localized under fluoroscopy. A 3 mm incision is made at this level. An 11 gauge biopsy needle is advanced into the fractured vertebral body via Trans or extra-pedicular approach depending on the fracture configuration and patient's anatomy.
A working cannula is inserted over the needle's trajectory. Once it's positioned, the needle is removed. (Figure 3 The inflation is stopped when the balloons reaches the cortical wall; Or, when we have "balloon kissing" position in the bi-pedicular approach (Figure 6). Balloon is deflated and subsequently removed when the cement is ready to be used. During inflation, an assistant prepares the cement to be injected. The cement is polymethylmetacrelate that needs 5 minutes to reach its semi-solid constitution. It's loaded in 5 injection cannulas The cement is then injected into the vertebral body's created cavity meticulously under fluoroscopy. From our observation, the cement fills the entire fracture tract first then it fills the created cavity.
Once packed and hardened, the cannula is removed. The incision is closed by single cutaneous layer suture.

Long term results
As far as the inclusion criteria were respected and for osteoporotic fracture mainly, pain relief was achieved with 24 hours in more than 60% of cases. The difference of pain relief and kyphotic deformity restoration are highly correlated to the time since the onset of the fracture. And though, patients presenting within 45 days showed optimal results. Whereas, patient presenting after 60 days necessitated moderate potency analgesics to achieve complete pain relief. Long term follow up, after 3, 6 and 12 months shows an increase in number of cases relieved by the treatment to (70 -82) % of the population that doesn't necessitate any analgesic use. (6 -8)%, who already has radicular pain before the procedure, necessitated 3-6 months of Gabapentin treatment. 1% necessitated another surgical procedure and, 9% achieved partial relieve of their pain.

Complications
During balloon kyphoplasty, untoward effect is minimal (3 -10) %. Minor complications, as cardiopulmonary toxicity defined by transient bradycardia and desaturation, were the most common.
Severe complications as cement pulmonary embolus (Perrin C et.al (1999)), extravasation to the epidural space or to the foraminae are rare (Moreland DB et.al (2001)). The risk of pulmonary embolism is 0.01 -1%. The rate of extrusions is 8.5%. Nevertheless, most of these extrusions are clinically asymptomatic and the rate of serious problems remains low.
In the literature, the overall clinically significant rate of complication is described as 1%.

Cement embolus
Cement pulmonary embolus are due to hazardous extravasation of the cement to the venous system. The latter is avoided by ascertaining the position of the injector in the middle of the cavity created by the inflated balloon. Clinically, cement pulmonary embolism presents by desaturation with heart rate changes. Thus monitoring is mandatory during the procedure. The procedure should be stopped and management of expected cement pulmonary embolism should be started.

Extravasation to the epidural space or foramina
It's the most common complication (Figure 10). Two third of those patients will necessitate open surgical decompression. This complication can be avoided if cement is left to become thick for 5 minutes after injection and the removal of the cannula should be done slowly in rotating manner.

Conclusion
Despite being relatively a new technique, balloon kyphoplasty becomes popular. It showed, in all studies conducted, that it's an effective method for treating pain and kyphosis induced by osteoporotic vertebral fractures. With the increase in indications and use of this technique, advancement in injection kits decreased the rate of complications. In experienced, well trained hands in the field, balloon kyphoplasty is safe and efficient technique for several types of fractures. Osteoporosis is a public health issue worldwide. During the last few years, progress has been made concerning the knowledge of the pathophysiological mechanism of the disease. Sophisticated technologies have added important information in bone mineral density measurements and, additionally, geometrical and mechanical properties of bone. New bone indices have been developed from biochemical and hormonal measurements in order to investigate bone metabolism. Although it is clear that drugs are an essential element of the therapy, beyond medication there are other interventions in the management of the disease. Prevention of osteoporosis starts in young ages and continues during aging in order to prevent fractures associated with impaired quality of life, physical decline, mortality, and high cost for the health system. A number of different specialties are holding the scientific knowledge in osteoporosis. For this reason, we have collected papers from scientific departments all over the world for this book. The book includes up-to-date information about basics of bones, epidemiological data, diagnosis and assessment of osteoporosis, secondary osteoporosis, pediatric issues, prevention and treatment strategies, and research papers from osteoporotic fields.