Barzilai University Medical Center

30 Research Day 2020 Barzilai University Medical Center 16 THE INFLUENCE OF KNEE BOLSTER ON LUMBAR SPINAL STENOSIS PARAMETERS ON MR IMAGES Azaria Simonovich 1 , Anna Nagar Osherov 1 , Lina Linov 1 , Leonid Kalichman 2 1 Department of Radiology, Barzilai University Medical Center, Ashkelon, Israel 2 Department of Physical Therapy, Recanati School for Community Health Professions, Faculty of Health Sciences, Ben-Gurion University of the Negev. Background Magnetic resonance imaging (MRI) of the lumbar spine is performed in a supine position. Occasionally, the patient’s legs are supported by a knee bolster. Its use is determined by the technician and the patient’s preferences. However, it is possible that certain spinal parameters are influenced by the degree of knee flexion. Hypothesis Spinal parameters evaluated on MRI without knee bolster will show a stronger association with low back pain-related disability. Objective To estimate the effect of the knee bolster use during an MRI on lumbar spinal stenosis parameters and low back painrelated disability. Methods A repeated-measurement study of 27 males and 19 females with mean age 55.78 ± 14.36, referred for an MRI of the lumbar spine due to low back pain, performed with and without standard knee bolster. A radiologist evaluated the lumbar lordosis Cobb’s angle, the cross-sectional area of the right and left intervertebral foramina and spinal canal. Spinal symptoms were evaluated by the Oswestry Disability Questionnaire. Results The Cobb angle of lumbar lordosis was found significantly greater on an MRI performed without knee bolster than with bolster (47.30 ± 9.90 vs. 42.57 ± 10.62, p < 0.001). The cross-sectional area of the intervertebral foramina and spinal canal at all evaluated levels was smaller when performed without knee bolster than with bolster. The Cobb angle, measured with and without knee bolster, showed significant positive correlations with back pain while standing and walking. The spinal canal area without knee bolster showed greater correlations with the Oswestry score parameters than with knee bolster. Conclusions MR images taken without knee bolster showed greater correlations of the spinal canal cross-sectional area with the Oswestry score than ones with knee bolster. Thus, one may prefer MR images acquired without a bolster below the knee compared to an MRI with a knee bolster.