In vitro biomechanical analysis of a new lumbar low-profile locking screw-plate construct versus a standard top-loading cantilevered pedicle screw-rod construct: Technical report
Objective: A standard top-loading lumbar pedicle screw-rod system is compared with a pedicle screw-plate system with smaller-diameter screws, more medial entry, and lower profile to assess the relative stability, strength, and resistance to fatigue of the 2 systems. Methods: Seven human cadaveric specimens were studied with each surgical construct. Nondestructive, nonconstraining pure moments were applied to specimens to induce flexion, extension, lateral bending, and axial rotation while recording L5-S1 motion optoelectronically. After initial tests, specimens were fatigued for 10 000 cycles and retested to assess early postoperative loosening. Specimens were then loaded to failure in hyperextension. Results: The standard screw-rod construct reduced range of motion to a mean of 20% of normal, whereas the screw-plate construct reduced range of motion to 13% of normal. Differences between systems were not significant in any loading mode (P > 0.06). The 14% loosening of the screw-rod system with fatigue was not significantly different from the 10% loosening observed with the screw-plate system (P > 0.15). Mean failure loads of 30 Nm for screw-rod and 37 Nm for screw-plate were also not significantly different (P = 0.38). Conclusion: Posterior fixation at L5-S1 using the low-profile screw-plate system offers stability, resistance to fatigue, and resistance to failure equivalent to fixation using a standard cantilevered pedicle screw-rod system. Copyright © 2010 by the Congress of Neurological Surgeons.
Digital Object Identifier (DOI)
Crawford, Neil R.; Doǧan, Şeref; Yüksel, K. Zafer; Villasana-Ramos, Octavio; Soto-Barraza, Julio C.; Sawa, Anna G.U.; Porter, Randall W.; Marciano, Frederick F.; and Theodore, Nicholas, "In vitro biomechanical analysis of a new lumbar low-profile locking screw-plate construct versus a standard top-loading cantilevered pedicle screw-rod construct: Technical report" (2010). Neurobiology. 779.