Technical and Metabolic Risk Factors Found in Vertebral Compression Fractures
Severe pain, loss of mobility and independence, disability, hospitalization, depression, and decreased quality of life are all possible consequences of vertebral compression fractures. Even with today's improved treatment for this problem, one out of every five adults who experience a vertebral compression fracture will suffer another one within the next 12 months.

What can be done to stop this potentially devastating health problem? Vertebral compression fracture refers to a mini-collapse of a vertebra in the spine. Tiny fracture lines in the bone (usually the front half of the vertebra) result in the bone taking on a wedge- or pie shape when viewed on X-rays from the side.

This type of fracture is most common in older adults who have osteoporosis (decreased bone mass or brittle bones). Just the weight of the body and pressure from postural changes (stooped head and shoulders) can put enough pressure (or compression, hence the name compression fracture) on the bone to cause a collapse.

It makes sense then to explore ways bone metabolism might contribute to the development of vertebral compression fractures. One specific measure that can be used is the level of vitamin D, a vitamin known to be important in the building of strong bones.

In this study, researchers from the Athens, Greece Laboratory for the Research of Musculoskeletal System take a closer look at the role of hypovitaminosis D as a risk factor for second (or third) vertebral compression fractures in postmenopausal women after having a kyphoplasty procedure. The balloon kyphoplasty procedure is designed to restore height of the fractured and collapsed vertebra.

Two long needles are inserted through one or both sides of the spinal column into the fractured vertebral body. These needles guide the surgeon while drilling two holes into the vertebral body. The surgeon uses a fluoroscope (special 3-D real-time X-rays) to make sure the needles and drill holes are placed in the right spot.

The surgeon then slides a hollow tube with a deflated balloon on the end through each drill hole. Inflating the balloons restores the height of the vertebral body and corrects the kyphosis deformity. Before the procedure is complete, the surgeon injects bone cement into the hollow space formed by the balloon. The cement is injected a little bit at a time until the cavity is filled. They try to keep most of the cement in the front three-fourths of the vertebral body. This fixes the bone in its corrected size and position and supports the front part that has collapsed the most.

This procedure halts severe pain and strengthens the fractured bone. However, it also gives the advantage of improving some or all of the lost height in the vertebral body, helping prevent or correct kyphosis. It does not, however, prevent a second or subsequent fracture from occurring at the next (adjacent) level. In fact, there is some concern that the kyphoplasty might actually increase the risk of another vertebral compression fracture.

Another possible reason for recurrent vertebral fractures is bone metabolism. Decreased bone mineral density from altered bone metabolism may be an important risk factor in compression fractures. To test this idea out, these researchers measured bone mineral density and bone turnover after 98 kyphoplasty procedures performed in 40 women. Blood levels of calcium and phosphate were measured along with parathyroid hormone levels (important in maintaining good calcium levels in the blood) and vitamin D.

Patients who developed a second vertebral fracture were compared with those who did not. X-rays were taken at regular intervals during the first 18 months after the kyphoplasty procedure. Other possible variables were evaluated, too such as age, body mass index, history of tobacco use, and the use of antiosteoporosis medications.

Bone mineral density was not statistically different between the two groups. Even so, 22.5 per cent of the entire group developed a second compression fracture. What made the difference between the two groups (those who did fracture versus those who did not)?

The women who did experience further fractures had lower levels of vitamin D (metabolic factor) and experienced cement leakage (technical factor) into the disc area from the first kyphoplasty. The cement increases how stiff the treated vertebra becomes, which then increases the load placed on the next vertebra. The women who did NOT have a second compression fracture were more likely to be taking calcium and Vitamin D supplementation along with antiosteoporosis medication.

The authors suggest two things as a result of their findings in this study. First, patients with vertebral compression fractures should be evaluated for bone metabolism before treatment begins for the fracture(s). Other risk factors for possible recurrent fractures should be noted (e.g., decreased vitamin D levels). And every effort should be made to prevent cement leakage during the procedure.
Christos P. Zafeiris, MSc, MD, et al. Hypovitaminosis D as a Risk Factor of Subsequent Vertebral Fractures After Kyphoplasty. In The Spine Journal. April 2012. Vol. 12. No. 4. Pp. 304-312.