[Use of bioceramics in the treatment of fractures of the thoraco-lumbar spine].

PURPOSE OF THE STUDY

The primary reduction and stabilization of all types of injury to the thoracolumbar spine is currently performed from the posterior approach by an internal, transpedicular fixator. The exceptions are type A fractures, according to the AO classification, that can primarily be treated from the anterior approach. The aim of the study was to assess the effect of BAS-O bioceramic granules, inserted by transpedicular approach, on the development of post-operative kyphosis of the segments injured.

MATERIAL

Between 1997 and 2001 we treated anterior spinal column fractures, using bioceramic granules in combination with an internal fixator, in 53 patients (40 men, 13 women: age 26 to 69 years; average, 42.3 years) at the Department of Orthopedics and Traumatology of the Third Faculty of Medicine and FNKV in Prague. However, only 42 patients (33 men, 9 women; age 28 to 67 years; average, 41.6 years) who had had the metal fixator removed more than six months previously were included in the study. The fixator was removed in the range of 10 to 24 months after the primary operation. The sample was divided into two groups; one with bioceramic material inserted in the body of the damaged vertebra (20 patients) and the other bioceramic granules implanted in both the vertebral body and the intervertebral space (22 patients).

METHODS

In all the patients, the standard procedure included transpedicular application of Schanz's screws and an USS FS fixator (Synthes). If necessary, distraction of the segment injured and the correction of lordosis were carried out. Further transpedicular procedures to treat the anterior spinal column were as follows: If the vertebral body was injured without destruction to the intervertebral disc, a bent elevator was inserted through the vertebral foramen and the intervertebral joints were reduced. At the same time, a cavity for application of bioceramic granules was created. These were inserted, using a funnel and a pusher, in the anterior part of the injured body. If the fracture involved a destroyed intervertebral disc, the disc was removed, the vertebral end plate of the adjacent vertebra was perforated and bioceramic granules were inserted in both the vertebral body and intervertebral space. Subsequently, spongeous bone grafts were harvested from the ilium and massively applied to the previously decorticated transverse and articular processes.

RESULTS

In the group of patients who had bioceramic granules inserted in only the vertebral body, the kyphotic angle was on average 10.36 degrees after injury and 2.86 degrees after surgery; therefore, a correction by 13.22 degrees was achieved. At 3 and 6 months after surgery, the kyphotic angle was 2.71 degrees and 2.68 degrees, respectively; at 3 and 6 months after fixator removal, it was 0.67 degree in both instances. In the group of patients with bioceramic granules implanted in both the vertebral body and intervertebral space, the kyphotic angle was on average 9.16 degrees after injury and 4.26 degrees after, surgery; therefore, a correction by 13.43 degrees was achieved. At 3 and 6 months after surgery, the kyphotic angle was -4.11 degrees and -4.00 degrees, respectively; at 3 and 6 months after fixator removal, it was 2.38 degrees and 2.44 degrees, respectively.

DISCUSSION

Our results revealed differences between the patients who had bioceramic granules inserted in only the vertebral body and those who had them also in the intervertebral space. At 6 months after surgery, the first group showed the loss of correction per two segments to be 3.53 degrees on the average, whereas the second group had a loss of 6.70 degrees, i.e., twice as high. This may be explained by a more serious damage to the intervertebral disc in the latter group. Only small differences between the groups were found in the kyphotic angle at both 6 months after surgery and 3 to 6 months after fixator removal. This implied that, in both groups, the loss of correction occurred in the period up to 3 months after removal of the fixator.

CONCLUSIONS

Bioceramic granules provide material for replacement of osseous tissue in the body of the vertebra as well as conditions necessary for bone restructuring. The loss of correction per segment is lower by about half in patients treated with bioceramic granules than in those who received a spongeous bone grafts.