Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P38. Prevalence of low bone mineral density measured by quantitative computed tomography (QCT) in 296 consecutive lumbar fusion patients

Abstract

BACKGROUND CONTEXT Metabolic bone disease is a public health concern affecting approximately 200million people worldwide. In 2010, USA prevalence of low bone mineral density (BMD) was 43.9% and osteoporosis 10.3% in adults >50years. Patients with bone disease may require intervention prior to elective spinal fusion procedures. BMD can be assessed radiographically using dual-energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT). QCT may have advantages over DXA for diagnosing low BMD in the lumbar spine. The American College of Radiology (ACR) defines the diagnostic criteria for the average QCT measurements at L1/L2 as follows: BMD>120 mg/cm3=normal, 80 mg/cm3 PURPOSE To determine the prevalence of low bone mineral density measured by quantitative computed tomography in patients undergoing lumbar spine fusions. STUDY DESIGN/SETTING Retrospective review or single academic center. PATIENT SAMPLE A total of 296 consecutive lumbar spine fusion patients. OUTCOME MEASURES Lumbar spine bone mineral density measured by QCT. METHODS A review of prospectively collected clinical data from a single, academic institution was performed. All patients treated surgically for lumbar spine pathology that underwent fine-cut QCT scans preoperatively were eligible for inclusion. QCTs were anonymized and two investigators performed blinded BMD measurements at L1 and L2. Mean L1/L2 QCT measurements were calculated. Using the ACR criteria, patients were categorized as normal, osteopenic, or osteoporotic. Osteopenia and osteoporosis prevalence for the entire cohort and subgroup analyses based on age and gender were performed. The statistical significance level was set at p RESULTS A total of 296 consecutive patients (55.4% female) undergoing primary lumbar fusion procedures were enrolled from 2014 to 2017. All patients had preoperative fine-cut QCT scans performed including L1 and L2. Mean (SD) L1/L2 measurement was 118 mg/cm3 (37.8). Using ACR criteria, 123 (41.5%) were normal, 129 (43.6%) osteopenic, and 44 (14.9%) osteoporotic. There were no prevalence differences between gender or race (P>.05). Pts >50years (n=248, 48.8% osteopenia, 17.7% osteoporosis) had significantly higher disease prevalence than CONCLUSIONS In 296 consecutive patients undergoing lumbar spine fusion procedures, QCT analysis revealed 58.5% had pathologic bone density by ACR criteria. Patients >50years had substantially higher rates of low BMD compared to younger patients. Among patients with no history of low BMD, 49.6% met criteria for osteopenia or osteoporosis. Spine surgeons should be aware of the high prevalence of abnormal BMD in lumbar spine patients and the possibility that patients without a previous diagnosis may have osteopenia or osteoporosis.