Gender Specific Biomechanical Evaluation of Fifty Human Cadaveric Lumbopelvic Spines – Emphasis on the Kinematic Differences in Sacroiliac Joint Range of Motion

Introduction: Sacroiliac joint (SIJ) dysfunction reportedly accounts for 15–30% of patients presenting with low back pain. Gender stratification of previous clinical studies reveals a higher incidence of SIJ dysfunction in females compared to males. However, no biomechanical studies to date have reported the comparative kinematic properties of the sacroiliac region based on gender specificity. This study served to investigate the gender specific multidirectional flexibility properties of the SIJ with and without lumbosacral reconstruction.

Methods: A total of 50 cadaveric lumbopelvic spines were utilized. Multidirectional flexibility testing was performed at ±12.5Nm in flexion-extension, lateral bending and axial rotation from L2-pelvis. The SIJ range of motion (ROM), with and without sacral fixation, was compared between males and females. Linear regression/correlation analysis between SIJ ROM and age was also quantified.

Results: Females (n=25) demonstrated significantly greater intact SIJ ROM compared to males (n=25) during flexion-extension (2.1±1.0⁰ vs. 0.9±0.4⁰), lateral bending (0.7±0.4⁰ vs. 0.4±0.2⁰) and axial rotation (0.8±0.5⁰ vs. 0.5±0.3⁰) (p≤0.05). Differences in SIJ ROM between males and females remained significant following sacral fixation in all three bending modes. Comparisons between treatment conditions revealed significant increases in SIJ motion in flexion-extension and lateral bending following sacral fixation compared to the intact spine, regardless of gender. Linear regression/correlation analysis indicated significance between decreasing SIJ ROM and increasing age under flexion-extension (r2=0.18, p≤0.05), lateral bending (r2=0.16, p≤0.05) and axial rotation (r2=0.25, p≤0.05) for males but not females (p>0.05).

Conclusion : Females demonstrated significantly greater SIJ motion compared to males, with and without lumbosacral instrumentation. Significant correlation was found between increasing age and decreasing SIJ ROM for males but not for females. Clinical consideration should be given to these observations for patients presenting for index and revision lumbosacral surgical procedures.