711479 - Gender Specific Biomechanical Evaluation of Forty-four Human Cadaveric Lumbopelvic Spines – Emphasis on the Kinematic Differences in Sacroiliac Joint Range of Motion

Background: Gender stratification of previous clinical studies reveals a higher incidence of sacroiliac joint (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 multidirectional flexibility properties of the intact lumbopelvic spine and following lumbosacral instrumentation.


Purpose: SIJ dysfunction reportedly accounts for 15–30% of patients presenting with low back pain. Alterations in SIJ biomechanics, due to prior instrumented lumbosacral arthrodesis, trauma, osteoarthritis or pregnancy can cause debilitating pain, leading to impaired mobility. To our knowledge, the current investigation is the largest compilation of in vitro biomechanical data quantifying the gender specific kinematic properties at the SIJ, with and without lumbosacral reconstruction.

Study Design / Setting: In vitro cadaveric model.

Eligible Population: N/A

Length of Follow Up: N/A

Patient Accountability: N/A

Outcome Measure: Biomechanical range of motion data

Methods: A total of 44 cadaveric lumbopelvic spines (mean age 68.2 years) were utilized. In the current investigation. Multidirectional flexibility testing was performed at ±12.5Nm in flexion-extension, lateral bending and axial rotation from L2-pelvis with emphasis on the sacroiliac joint range of motion (ROM) under each loading modality. The specimens were first tested in the intact condition followed by transpedicular screw and rod instrumentation extending from L2 through S1. The SIJ range of motion, with and without sacral fixation, was compared to the intact condition and between males and females. Linear regression/correlation analysis was performed with comparisons between ROM, specimen age and gender.

Results: Females (n=20) demonstrated significantly greater intact SIJ ROM compared to males (n=24) 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 following sacral fixation (females: 2.9±1.4⁰; males: 1.3±0.7⁰) compared to the intact spine (females: 2.1±1.0⁰; males: 0.9±0.4⁰), regardless of gender (Figure 1). Linear regression and correlation analysis indicated significance between decreasing SIJ ROM and increasing age under flexion-extension (r2=0.18, p≤0.05), lateral bending (r2=0.17, p≤0.05) and axial rotation (r2=0.25, p≤0.05) for males but not females (p>0.05).

Conclusion: The unique biomechanical properties of the SIJ presents formidable challenges in spinal reconstructive surgery. Controversy exists as to effective surgical management of this joint. It is of clinical opinion that abnormal motion across the joint leads to dysfunction and instrumentation complications, but a paucity of data is available on the kinematic response. This serves as a comprehensive biomechanical evaluation of SIJ ROM comparing males and females. Gender-specific clinical consideration is advised for patients presenting for index and revision lumbosacral surgical procedures. The study highlights motion at the SIJ, which increases with fixation to the sacrum and is higher for females than males. Clinical consideration should be given to these observations for patients presenting for index and revision lumbosacral surgical procedures.