Transpedicular segmental fixation: description of a new procedure

Modified posterior decompression for the management of thoracolumbar burst fractures with canal encroachment

STUDY DESIGN

A retrospective study.

OBJECTIVE

The purpose of this study is to explore the application of a self-designed canal decompressor in the posterior surgical treatment of thoracolumbar burst fractures with canal encroachment.

SUMMARY OF BACKGROUND DATA

Surgical treatment is often indicated in the management of thoracolumbar burst fractures accompanied with canal encroachment. Efficient canal decompression would prevent progressive neurologic deterioration and facilitate recovery. Compared with anterior surgical methods, posterior approaches offer rigid fixation without formidable surgical onslaughts. However, the reduction of retropulsed bone fragments via posterior approaches is indirect and thus often inefficient.

METHODS

In this study, we designed and applied a canal decompressor in the surgical treatment of 48 cases of thoracolumbar burst fractures using posterior approaches. Canal comprise, Cobb's angles, residual vertebral body height, neurologic outcome, and back pain were evaluated preoperatively and postoperatively. Patients were followed for 18 to 28 months (mean 22.5 + or - 3.5 mo) on an outpatient basis.

RESULTS

Operations were performed within relatively short time and without significant blood loss. Radiographs indicated that applying the canal decompressor allowed efficient reduction of canal encroachment from preoperative 53.4% + or - 16.7% to postoperative 12.8 + or - 4.2%. Cobb's angles reduced from preoperative 31.0 + or - 2.5 degree to postoperative 5.1 + or - 0.6 degree. Mean vertebral height was restored to 82.5 + or - 5.7% after operations. Follow-up evaluation within 28 months indicated that neurologic recovery presented in 77.1% of patients, with average improvement of 0.86 Frankel grades. Neurologic deterioration was not observed.

CONCLUSIONS

Applying the canal decompressor enables efficient and safe reduction of bone fragments retropulsing into the canal in posterior operations. This technique thus provides an alternative method for the management of thoracolumbar burst fractures.

Surgical palliation of symptomatic spinal metastases

Spinal metastases are common in malignant disease. For selected patients with severe pain or neurological dysfunction, surgical treatment offers valuable palliation. During the last few years, we have treated between 100 and 120 patients annually with spinal metastases at the Department of Orthopedics, Uppsala University Hospital, Uppsala, Sweden. A detailed preoperative analysis is mandatory for optimal patient selection. Preoperative embolization of spinal metastases of renal cell carcinoma minimizes the peroperative blood loss. Most cervical spinal metastases are best treated via an anterior approach with vertebral body resection and primary reconstruction of the anterior column. Most thoracic or lumbar spinal metastases are best treated via a posterior approach with decompression and stabilization, using a transpedicular fixation device. However, patients with an expected survival exceeding 6-12 months, a secondary reconstruction of the anterior column should be considered.

A comparison study of treatment of thoracolumbar fractures using the ACE Posterior Segmental Fixator and Cotrel-Dubousset instrumentation

The results of 26 consecutive thoracolumbar fractures treated with Cotrel-Dubousset instrumentation (CDI) (n = 12) or the ACE Posterior Segmental Fixator (n = 14) with a mean follow up of 20.2 months were analyzed. Preoperatively, no statistically significant difference was noted between the two treatment groups. Postoperatively, no statistically significant difference was noted for improvement of kyphosis (mean: -6.00 degrees ACE, 1.92 degrees CDI), vertebral body height (mean: 17.86% ACE, 18.83% CDI), vertebral body angle (mean: -6.21 degrees ACE, -5.42 degrees CDI), or estimated blood loss (mean: 1544 cc ACE, 1620 cc CDI). All patients with incomplete paraplegia improved by at least one Frankel grade. Statistically significant differences were noted in operative time (mean: 269 minutes ACE, 357 minutes CDI, P < .0005), and in the number of instrumented levels (mean: 3 ACE, 5.8 CDI). All patients exhibited solid fusion radiographically. Thoracolumbar fractures can be effectively treated by either CDI or the ACE Fixator. The ACE Fixator has the advantage of sparing motion segments and decreased operative time.

Can lacerations of the thoraco-lumbar dura be predicted on the basis of radiological patterns of the spinal fractures?

Encroachment upon the spinal canal, separation of the pedicles, associated fractures of the laminae are assumed to be related to dural lacerations consequent to burst fractures of the thoracolumbar spine. Owing to the possible occurrence of early or delayed complications of meningeal discontinuations, the predictive value of these signs has been analyzed in a consecutive series of 50 patients, who were submitted to surgery. Dural tears were found to occur at a rate of 60%, without any statistically significant relation with any of the examined signs. The results were not consistent with the thesis that lacerations of the dura can be predicted on the basis of radiological signs.

Delayed worsening of the surgical correction of angular and axial deformity consequent to burst fractures of the thoracolumbar or lumbar spine

Forty-one patients with burst fractures of the thoracolumbar junction, or the lumbar spine (T12 to L5), were followed for 6-48 months (mean follow-up = 19.9 months) after early surgery (usually within 24 hours). Preoperative, early postoperative, and late postoperative degrees of kyphosis, as well as percent reduction of the height of the vertebral body were calculated and compared. Early postoperative radiologic evaluations showed a statistically significant difference (p < 0.0001) between the mean values of both parameters calculated respectively before and after surgery. The decrease of the surgical correction, from the initial postoperative radiographs to follow-up, was statistically significant (p < 0.0001). However, the final values were better when compared with the preoperative features (p < 0.003 and p < 0.0001, respectively for degree of kyphosis and reduction in vertebral height.

Transpedicular decompression and stabilization of burst fractures of the lumbar spine

Twenty-seven consecutive patients with neurological impairment due to burst fractures of the lumbar spine were operated upon, via the postero-lateral route, over a 38-month-period. Transpedicular fixation devices [posterior segmental fixator (PSF) or variable screw placement system (VSP)] were applied in all cases, in order to achieve short-segment fusion of the fractured spinal segment. Return to useful motor power or neurological normality (median follow-up: 18.7 months) occurred in 22 cases (81% of the whole series), with this outcome resulting in all but one of the cases with preoperative incomplete neurological deficit. Postoperative encroachment of the spinal canal, degree of kyphotic deformity, and reduction of the vertebral height showed statistically significant differences compared with the corresponding preoperative values.

Posterior reduction of a pathologic spinal fracture. A case of indirect anterior dural decompression

In a patient with paraparesis resulting from a pathologic fracture of Th9, which was due to a breast cancer metastasis, indirect anterior decompression via posterior reduction was performed. The rationale for the operation technique was the similarity between a pathologic fracture of the thoracolumbar spine and a traumatic burst fracture. The method, which uses a transpedicular reduction and fixation device, is substantially less invasive than a formal anterior decompression.

Near-anatomical reduction and stabilization of burst fractures of the lower thoracic or lumbar spine

Thirty-one consecutive symptomatic patients with burst fractures of the lower thoracic or lumbar spine (T 11-L4) were treated by early surgery in a 36-month period, with near-anatomical reduction being achieved via the postero-lateral route. Fusion and reconstruction of the vertebral body was done by using autologous or processed bovine bone. Correction of the kyphotic deformity was obtained by using distraction rods or transpedicular devices. The post-operative mean degree of kyphosis, percent vertebral height, and percent canal stenosis showed statistically significant differences, compared with the corresponding pre-operative mean values. All but one of the 25 patients with incomplete paraplegia exhibited neurological improvement, with complete recovery occurring in 20 cases (median follow-up: 16 months) irrespective of the location of the lesion at the thoraco-lumbar junction (T 11-L1) or the lower lumbar segment (L2-L4). Out of the 6 patients with pre-operative complete paraplegia, useful motor power returned in one case with a lesion below L1. The results confirm the suitability of the postero-lateral route and are consistent with the assumption that early near-anatomical reduction and stabilization favours maximum neurological recovery in symptomatic patients.