Lumbar-pelvic-femoral balance on sitting and standing lateral radiographs

Abstract

Trunk balance in upright stance expresses an individual postural strategy found on anatomic and functional parameters. The "pelvic vertebra" is an essential transitional region for the coherence of spinal parameters (notably, lumbar lordosis and thoracic kyphosis) and pelvic parameters (sacral slope, pelvic tilt and incidence). Deterioration of this postural harmony is often associated with spinal aging, maladjusted spinal arthrodeses, or mechanical abnormalities of the hip joints. Spinal surgeons are aware of the importance of detecting and analyzing sagittal imbalance, whether compensated or not. The influence of the hip joint, however, is underestimated and poorly objectified on conventional imaging, as are its interrelations with overall lower-limb posture. Currently, hip surgeons focus basically on the pelvis as bone reference in planning implantation, peroperative adjustment and failure analysis. The antero-posterior (AP) pelvic view is the gold standard, with lateral views being little used. Influenced by the classic anatomic attitude in favor of transverse slices in dorsal decubitus, CT is considered the reference method for "horizontal" assessment of the hip joint. The present study draws attention to a more global vision of the pelvic and subpelvic regions in the sagittal balance of the trunk, relying on the sitting as well as the standing posture, as both involve subtle mechanisms of adaptation governed by the pelvic incidence angle.

Does Degenerative Lumbar Spine Disease Influence Femoroacetabular Flexion in Patients Undergoing Total Hip Arthroplasty?

“…Previous studies have measured pelvic tilt in patients undergoing THA during sitting and standing positions, usually reporting values similar to ours with mean standing sacral slope angles between 35°and 40°, and mean sitting sacral slope angles between 14°and 24° [19,22,26]. Our study is the first, to our knowledge, to stratify patients undergoing THA into those with or without lumbar DDD, and we found that most patients with DDD had flattened backs (mean 7°less lumbar lordosis) and more posterior pelvic tilt (mean 5°more sacral slope) in standing.…”

“…This may not replicate how patients sit comfortably during their daily activities. However, previous studies used the same method [22,24].…”

“…Eleven patients who had spine ankylosis (with complete bridging osteophytes, ankylosing spondylitis, or diffuse idiopathic skeletal hyperostosis) or had surgical fusion as a treatment for their disc disease were excluded because spine fusion limits lumbar mobility [22]. Eleven additional patients (3%) with a BMI greater than 40 kg/m 2 were excluded because of poor EOS image quality.…”

“…The pelvis has been described as an intercalary bone in the lumbar-pelvic-femoral complex, or a ''pelvic vertebra'' [17,22], such that pelvic tilt is dependent on spinal and femoral alignment. As a patient sits with 90°of apparent hip flexion (brings his or her femurs approximately 90°to the vertical plane), there will be motion through the lumbar spine segments and/or the femoroacetabular articulation in the lumbar-pelvic-femoral complex.…”

“…As a patient sits with 90°of apparent hip flexion (brings his or her femurs approximately 90°to the vertical plane), there will be motion through the lumbar spine segments and/or the femoroacetabular articulation in the lumbar-pelvic-femoral complex. It has been shown that there is limited change in pelvic tilt from standing to sitting position in patients with spine stiffness or surgical fusion [19,22,23]. Therefore, these patients with stiff spines need to compensate for limited lumbar spine flexion by flexing more through the hip and potentially increasing the risk of impingement of the prosthetic femoral neck on the edge of the acetabular cup or bone and therefore the risk of prosthetic dislocation.…”