Dual-pitch screws allow for inline revision of pedicle screws, study finds

Inline revision of pedicle screws without increasing the screw diameter can be achieved using dual-pitch screws with cancellous pitch in the vertebral body and cortical pitch in the pedicle, according to a study published in The Spine Journal.

“Dual-pitch screws may allow for inline revision of screws without upsizing screw diameter, minimizing the risk of pedicle breach or fracture,” the study’s authors, including Leah Y. Carreon, M.D., of Norton Leatherman Spine, and orthopedic surgeons Jeffrey L. Gum, M.D., and Steven D. Glassman, M.D., of Norton Leatherman Spine and the University of Louisville School of Medicine Department of Orthopaedic Surgery.

Pedicle screws were tested in the lumbar vertebrae from 11 cadavers. Pedicle screws of 5.5-millimeter standard pitch were inserted and removed. One of four screw types — 5.5 millimeter standard pitch, 5.5-millimeter dual pitch, 6.0-millimeter standard pitch or 6.0 millimeter dual pitch — were inserted in the abandoned pedicles.

Under testing, there was no difference between the 5.5 millimeter dual pitch and the 6.0 millimeter standard pitch.

“Dual-pitch screws, with cancellous pitch in the vertebral body and cortical pitch through the pedicle, allows for inline revision of pedicle screws without upsizing screw diameter; reducing the risk of pedicle breach or fracture when exchanging screws,” the authors wrote as the clinical significance of the findings in “Dual Pitch Screw Design Provides Equivalent Fixation to Upsized Screw Diameter in Revision Pedicle Screw Instrumentation: A Cadaveric Biomechanical Study.”