Obesity Alters Spinopelvic Alignment Changes From Standing to Relaxed Sitting: the Influence of the Soft-tissue Envelope

Abstract

Background: Changes in spinopelvic and lower extremity alignment between standing and relaxed sitting have important clinical implications with regard to stability of total hip arthroplasty. This study aimed to analyze the effect of body mass index (BMI) on lumbopelvic alignment and motion at the hip joint. Methods: A retrospective review of patients who underwent full-body stereoradiographs in standing and relaxed sitting for total hip arthroplasty planning was conducted. Spinopelvic parameters measured included spinopelvic tilt (SPT), pelvic incidence (PI), lumbar lordosis (LL), PI minus LL (PI-LL), proximal femoral shaft angle (PFSA), and standing-to-sitting hip range of motion. Propensity score matching controlled for age, gender, PI, and hip ostoarthritis grade. Patients were stratified into normal (NORMAL; BMI, 18.5-24.9), overweight (OW; 25.0-29.9), and obese (OB; 30.0-34.9) groups. Alignment parameters were compared using one-way analysis of variance. Results: There were 84 patients in each group after propensity score matching. Standing alignment between BMI groups was similar for all parameters (P > .05) except for PFSA (P < .001). Significant differences were noted for sitting alignment between patients who are NORMAL, OW, and OB in: SPT (P ¼ .007), PILL (P ¼ .018), and LL (P ¼ .029). PFSA between groups was not significantly different (P > .05). Significant differences were found for sitting-to-standing alignment across groups in PFSA change (P < .001), SPT change (P ¼ .006), PILL change (P ¼ .005), LL change (P ¼ .037), and hip flexion (P < .001). Conclusions: Significant differences in sitting and standing-to-sitting change in lumbopelvic alignment based on BMI suggest obese patients recruit more posterior spinopelvic tilt when sitting to compensate for soft-tissue impingement that occurs anterior to the hip joint and limiting hip flexion.

A radiographic and physical analysis of factors affecting seat belt position in sitting car seat

“…There have been no reports mentioning the relationship between spinopelvic alignment and SBS. Buckland et al reported that the pelvis tends to tilt posteriorly in obese individuals 30 . Nishida et al investigated changes in spinal alignment in the sitting position while seated in a car seat, and reported that there were differences depending on body shape even in the same seat 31 .…”

Does obesity affect acetabular cup position, spinopelvic function and sagittal spinal alignment? A prospective investigation with standing and sitting assessment of primary hip arthroplasty patients

“…As it is known that individual restricted segments of the spinopelvic complex are overcompensated by the other segments. This is reflected in patients with lumbar spine degeneration through increased hip motion and pelvic recruitment (“hip users”), but conversely also through limited hip motion and pelvic stiffness in patients with osteoarthritis of the hip with increased lumbar flexibility (“spine users”) [ 18 , 50 ]. Accordingly Yeung et al also reported limited hip flexion in obese THA patients in a clinical examination [ 51 ].…”

“…In our study, the relaxed seated position was selected as the functional assessment and a deep flexed seated or single leg standing position was not performed as an additional functional exercise. These functional images were not possible in the postoperative setting due to patient safety [ 7 , 9 , 50 ]. When evaluating the results, it needs to be considered that the implant positioning was performed in supine position, the spinopelvic assessment analyzed the relaxed seated and standing position, with known strong correlations between standing and supine position [ 61 ].…”

Validation of a Novel Software Measurement Tool for Total Hip Arthroplasty

“…These existing products provide important information for both the planning and evaluation phases of procedures; however, as they focus on measurements from a single radiograph view, the data they provide is somewhat limited. With the recent advancements in implant technology and an increased focus on the biomechanical relationship between the hip and spine in THA [13][14][15][16], software that expands the data available and considers these factors would be a valuable asset to THA planning and evaluation. Likewise, advancements in intraoperative technology such as computer-assisted navigation, which can measure component position relative to a number of anatomic planes, have highlighted the limitations of traditional radiographic measurement software, which measures component position in only one plane [17][18][19].…”