AB088. SOH24AB₁72. Lumbar disc herniations in females: comparative risk factors for pre-menopausal versus post-menopausal cohorts and emerging etiopathogenesis of disc disease in younger patients

Background: Lumbar disc disease can prove a debilitating injury. Typically, it is believed to be a multifactorial process inclusive of aging, obesity and abnormal biomechanical loading patterns in the spine. Nevertheless, traditional theories of pathophysiology may not hold true for younger populations. That serves the premise for this study, to investigate comparative risk factors for lumbar disc herniation (LDH) in pre- and post-menopausal female cohorts. Methods: A retrospective review was conducted at our institution, a national tertiary referral centre, for female patients who underwent surgery for symptomatic LDH between June 2016 and May 2020. Patients were separated into two specific cohorts; those aged <45 years of age at the time of injury, termed the pre-menopausal cohort and those aged ≥45 years of age at the time of injury, termed the post-menopausal cohort. Demographic, clinical and radiological characteristics were collected and compared between groups. Results: A total of 110 patients were identified (43 pre-menopausal, 67 post-menopausal). On univariate analysis, the pre-menopausal cohort had a significantly higher body mass index (BMI) (29.6 vs. 27.1 kg/m2; P=0.02), history of LDH (P=0.02), history of lumbar spine surgery (P=0.02), greater degree of psoas fat infiltration (P<0.001), lumbar lordosis (P<0.01) and proportion of distal lumbar lordosis (P=0.01). On multivariate analysis, only psoas fat infiltration retained its significance odds ratio (OR): 1.78, 95% confidence interval (CI): 1.22:2.97, P<0.01. Conclusions: Our findings show that pre-menopausal patients who presented with LDH were at risk of LDH due to a significantly greater degree of psoas fat infiltration when compared to the post-menopausal group.