The Comparision Of Transvertebral Internal Fixation With Monoaxial And Polyaxialpedicle Screws Respectvely For Thoracolumbar Fracture

Objective To explore the difference effectiveness of transvertebral internal fixation with monoaxial and polyaxial pedicle screws respectively for thoracolumbar fractures.Methods The study involved single-level thoracolumbar fracture patients without spinal neurological deficits undergone the posterior internal fixation with pedicle screws from January2009to June2013. Three level vertebras were immobilized by six pedicle screws. They were distributed into two groups: monoaxial screws group was fixed with monoaxial screws for the injured vertebra as well as the upper and lower adjacent vertebras, polyaxial screws group was fixed with polyaxial screws for the injured fractured vertebra but monoaxial screws for the superior and inferior adjacent vertebra. General inform ation, the anterior and posterior height of the injuried vertebral body, the kyphosis angle of injuried vertebral body, Cobb angle (respective abbreviation:anterior height, posterior height, kyphosis angle, Cobb angle) were assessed and compared between two groups after operation so as to estimate the ability of correction of fracture and kyphosis deformity.Visual analogue scale(VAS)and Oswestry disability index(ODI)were used to evaluate alteration of back pain and lower limb function, and incidence of screw breakage was also compared.Result Totally,46patients were enrolled in the study and received an average follow-up of12months(range6to18months). Two groups had no statistical differences in general information(sex, age, fracture levels, time before operation, fracture types) and intraoperative information(operation time, blood loss).The preoperative datas[anterior height, posterior height, kyphosis angle, Cobb angle:monoaxial screws group (59.1±10.2%,92.2±3.0%,20.8±3.9°,19.0±5.6°), polyaxial screws group (57.8±12.4%,92.0±3.0%,21.4±5.6°,19.9±7.2°) respectively, P>0.05] had no statistical differences between two groups. The correction of aforementioned items (anterior height, posterior height, kyphosis angle, Cobb angle) also had no differences (P>0.05). At the latest follow-up, The correction loss of monoaxial screws group was less than polyaxial screws group (P<0.05]), but Cobb angle was similar (P>0.05). The pairwise comparison of data (anterior height, kyphosis angle,) at two point-in-times (3days after operation, the latest follow-up) had no significant statistical difference in monoaxial screws group (P>0.05), and also posterior height at (reoperative, the latest follow-up) in two groups. The other comparison at three point-in-times (reoperative,3days after operation, the latest follow-up) had a significant statistical difference in each group. Operation time, blood loss, VAS and ODI in the same period after operation were similar between two groups (P>0.05). One screw happened to break in monoaxial screws group.Conclusion The transvertebral fixation with monoaxial and polyaxial pedicle screws improves kyphosis deformity and correction of fracture, but the monoaxial pedicle screws have superiority of correction loss.