Biomechanical demands on posterior fusion instrumentation during lordosis restoration procedures.

OBJECTIVE The goal of this study was to investigate the forces placed on posterior fusion instrumentation by 3 commonly used intraoperative techniques to restore lumbar lordosis: 1) cantilever bending; 2) in situ bending; and 3) compression and/or distraction of screws along posterior fusion rods. METHODS Five cadaveric torsos were instrumented with pedicle screws at the L1-5 levels. Specimens underwent each of the 3 lordosis restoration procedures.

Biomechanical Determination of Distal Level for Fusions across the Cervicothoracic Junction.

Study Design In vitro testing. Objective To determine whether long cervical and cervicothoracic fusions increase the intradiscal pressure at the adjacent caudal disk and to determine which thoracic end vertebra causes the least increase in the adjacent-level intradiscal pressure. Methods A bending moment was applied to six cadaveric cervicothoracic spine specimens with intact rib cages.

Biomechanical analysis of derotation of the thoracic spine using pedicle screws.

Study Design: Biomechanical analysis of derotational load-to-failure of pedicle screw (PS) instrumentation in cadaveric thoracic spinal segments.

Objective: To investigate the derotational torque that can be applied to the thoracic spine through different linked constructs and evaluate the modes of failure.

Summary Of Background Data: Thoracic derotation with PSs has been shown to provide better 3 plane correction than other methods but the effects of linked PS constructs has not been studied.