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  • Comprehensive Biomechanical Analysis of Three Reconstruction Techniques Following Total Sacrectomy - An In-Vitro Human Cadaveric Model

    Final Number:

    Mohamad Bydon MD; Mohamed Macki BA; Rafael De la Garza-Ramos MD; Ashley Murgatroyd; Kenneth Mullinix; Bryan W. Cunningham MSc; Ali Bydon MD; Ziya L. Gokaslan MD

    Study Design:
    Laboratory Investigation

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2015 Annual Meeting

    Introduction: The objective of this study is to compare the biomechanical stability of three distinct techniques for sacral reconstruction in vitro.

    Methods: Eight intact human lumbo-pelvic specimens (L1 – pelvis) were tested for flexion-extension, lateral bending, axial rotation, and axial compression including segmental translation about the ±Y axis and ±Z axis. Following intact analysis, each specimen underwent total sacrectomy and reconstruction as follows: segmental pedicular instrumentation of the lumbar spine plus bilateral spinal rods anchored with iliac screws (Model 1), addition of a transiliac rod (Model 2), and addition of two spinal rods and two S2 screws (Model 3).

    Results: The flexion-extension range of motion at L4-L5 in Model 1 (1.54 ± 0.94), Model 2 (1.51 ± 1.01), and Model 3 (0.72 ± 0.62) were significantly lower than the intact condition (6.34±2.57). For the Model 3 treatment, the mean range of motion at both the L5-Right ilium (2.95 ± 1.27) and L5-Left ilium (2.87 ± 1.40) were significantly less than all other treatments at the same level. Under lateral bending loading, the mean range of motion for the intact condition at L5-S1 (4.62 ± 2.37), L4-L5 (6.68 ± 3.81), L5-Right ilium (4.95 ± 2.41), and L5-Left ilium (4.92 ± 2.37) were significantly greater than all three subsequent reconstruction groups. The axial rotation range of motion at L4-L5 for Model 1 (2.01 ± 1.39), Model 2 (2.00 ± 1.52), and Model 3 (1.15 ± 0.80) were significantly lower than the intact condition (5.02 ± 2.90) (p<0.05).

    Conclusions: The current biomechanical study demonstrates a definitive kinematic advantage of Model 3 reconstruction method with regard to lumbopelvic range of motion. From a biomechanical standpoint, implementation of four iliac screws and four rods results in greater stability than bilateral rods and iliac screws, with or without transverse iliac fixation.

    Patient Care: Give insight into the biomechanical properties of three reconstruction techniques following sacrectomy, and thus provide clinicians with evidence regarding the reconstruction techniques.

    Learning Objectives: 1. Know the biomechanical differences of three reconstruction techniques following total sacrectomy


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