Modification of the Spinopelvic Parameters With Surgical Positioning and the Role of the Hip

Abstract

Post-operative lumbar pain is related to alterations in the sagittal and spinopelvic parameters. A lumbar fusion that fails to maintain, or that worsens the physiological lordosis alters the sagittal balance. Objective: To analyze spinopelvic variation in different surgical positions. Methods: A prospective, analytical and comparative study of spinograms, lumbosacral radiographs in the surgical position over a 4-pole quadratus lumborum, and lumbosacral radiographs with quadratus lumborum and support in the knees. A sample of 129 patients, of both sexes, aged between 18 and 60 years, and presenting with lower back pain. Lumbar Lordosis (LL), Pelvic Tilt (PT), Pelvic Incidence (PI) and Sacral Slope (SS) were measured. Results: PI was the most stable parameter. With quadratus lumborum, a slight increase in PT, a decrease in SS and a significant reduction in LL were found. With quadratus lumborum and support in the knees, a decrease in PT and a slight increase in SS were found, while the LL value remained similar to that of the spinogram. Conclusion: The intraoperative position with hip flexion of between 40° and 45° over quadratus lumborum reduced LL to 10.52° in men and 16.21° in women, increased PT, and decreased SS. The intraoperative position with hip flexion of between 0° and 10° showed the same values as the reference spinogram. Level of Evidence II; Prospective comparative study.