A biomechanical comparison of a novel thoracic screw fixation method: transarticular screw fixation vs traditional pedicle screw fixation.

Background: Transarticular screw fixation is used in the upper cervical and lumbar spine to achieve posterior spinal stability, and its biomechanical performance has been proven to be similar to that of pedicle screw fixation. However, few studies have reported the use of transarticular screw fixation in the upper thoracic spine.

Objective: To biomechanically compare transarticular screws with pedicle screws in short-term cyclic loading in the upper thoracic spine.

Methods: Eight fresh human cadaveric spine specimens (T1-T3) were harvested and tested for 6 cycles in flexion, extension, lateral bending, and torsion in their intact condition. Each specimen was then destabilized and restabilized with 3 fixation methods: the pedicle screw/rod construct, the transarticular screw/rod construct, and transarticular screws alone. The instrumented specimens were reteted with the same protocol.

Results: All fixation systems reduced the range of motion significantly with respect to flexion, extension, lateral bending, and axial rotation (P < .01). However, no significant difference was observed between the 3 instrumented groups.

Conclusions: This biomechanical study demonstrates in vitro that transarticular screws and pedicle screws have statistically similar biomechanical stability in a noncorpectomy model. Posterior transarticular screws may be an alternative for internal fixation in the upper thoracic spine.