Laminar Screw an Acceptable Alternative in C7 Fixation
Laminar screw offers similar motion limits and pull-out strength to pedicular screw in vitro
MONDAY, March 21 (HealthDay News) -- Laminar screws used in spine fixation of C7 may be a better alternative than lateral mass screws when the use of a traditional transpedicular screw is unfavorable, according to a study published in the March 1 issue of Spine.
Jae Taek Hong, M.D., Ph.D., of the Catholic University of Korea in Suwon, and colleagues compared the in vitro stability of C7 fixation with the newer intralaminar screw to the stability achieved with either the transpedicular screw or the lateral mass screw. The researchers studied 10 human cadaveric C6 to C7 motion segments before and after fixation with the three screw types, evaluating the kinematics and pull-out strength of each screw.
The researchers found that pedicle screw fixation was the strongest instrumentation method for fixing C7. Compared to the range of motion achieved with the pedicle screw, the laminar screw was not significantly different in flexion/extension and axial rotation, but was significantly weaker in terms of its lateral bending range of motion. The two screws had similar pull out strengths. The lateral mass screw was equivalent to the pedicle screw in flexion/extension and lateral bending, but achieved inferior axial rotation and pull-out strength.
"These results suggest that pedicle screws provide the strongest fixation in C7, as expected. But in the cases that pedicle screw is not favorable or when pedicle screw should fail, the use of C7 laminar screws seems to be better than lateral mass screw," the authors write.