Association between global sagittal malalignment and increasing hip joint contact force, analyzed by a novel musculoskeletal modeling system.

Takanori Miura,Naohisa Miyakoshi,Kimio Saito,Akira Komatsu,Jumpei Iida,Takehiro Iwami,Kazutoshi Hatakeyama,Yoichi Shimada,Tosiki Matsunaga,Kotaro Suzuki,Hiroaki Kijima,John Leicester Williams

doi:10.1371/journal.pone.0259049

Abstract

Patients with adult spinal deformity have various standing postures. Although several studies have reported a relationship between sagittal alignment and exacerbation of hip osteoarthritis, information is limited regarding how spinopelvic sagittal alignment changes affect hip joint loading. This study aimed to investigate the relationship between sagittal spinopelvic-lower limb alignment and the hip joint contact force (HCF) using a novel musculoskeletal model. We enrolled 20 women (78.3±6.7 years) from a single institution. Standing lateral radiographs were acquired to measure thoracic kyphosis, lumbar lordosis, the pelvic tilt, sacral slope, sagittal vertical axis (SVA), femur obliquity angle, and knee flexion angle. In the model simulation, the Anybody Modeling System was used, which alters muscle pathways using magnetic resonance imaging data. Each patient’s alignment was entered into the model; the HCF and hip moment in the standing posture were calculated using inverse dynamics analysis. The relationship between the HCF and each parameter was examined using Spearman’s correlation coefficient (r). The patients were divided into low SVA and high SVA groups, with a cutoff value of 50 mm for the SVA. The HCF was 168.2±60.1 N (%BW) and positively correlated with the SVA (r = 0.6343, p<0.01) and femur obliquity angle (r = 0.4670, p = 0.03). The HCF were 122.2 and 214.1 N (75.2% difference) in the low SVA and high SVA groups, respectively (p<0.01). The flexion moment was also increased in the high SVA group compared with that in the low SVA group (p = 0.03). The SVA and femur obliquity angle are factors related to the HCF, suggesting an association between adult spinal deformity and the exacerbation of hip osteoarthritis. Future studies will need to assess the relationship between the hip joint load and sagittal spinopelvic parameters in dynamic conditions.

Highlights

The spine and hip joint are anatomically and functionally adjacent via the pelvis, and changes in one joint can potentially clinically affect the other
Spinal parameters included in this analysis were thoracic kyphosis (TK: Cobb angle from the upper endplate of T4 to the lower endplate of T12), lumbar lordosis (LL: Cobb angle from the upper endplate of L1 to the lower endplate of S1), and the sagittal vertical axis (SVA: horizontal distance from the C7 plumb line originating at the middle of the C7 vertebral body to the posterior superior endplate of S1)
Pelvic parameters included in this analysis were the pelvic tilt (PT: the angle between the line connecting the midpoint of the sacral plate to the bi-coxo-femoral axis and the vertical plane), sacral slope (SS: the angle between the sacral plate and the horizontal plane), and pelvic incidence (PI: the angle between the line perpendicular to the sacral plate and the line connecting the midpoint of the sacral plate to the bi-coxo-femoral axis)

Summary

Introduction

The spine and hip joint are anatomically and functionally adjacent via the pelvis, and changes in one joint can potentially clinically affect the other. Offierski and MacNab discussed the relationship between hip osteoarthritis (HOA) and lumbar spine disease and described the hip-spine syndrome (HSS). They categorized this syndrome into four groups: simple, complex, secondary, and misdiagnosed. With respect to secondary HSS, HSS is defined as a pathological condition wherein the primary pathological structure is the spine that affects the hip joint, and the sagittal spinopelvic alignment assessment is important to understanding hip-spine relationships [2, 3]. Several studies have reported some relationship between sagittal spinal alignment and exacerbation of HOA, such as lumbar kyphosis and posterior pelvic tilt are more frequent in elderly onset HOA [6], and the larger anterior inclination of the spine in the standing position is associated with radiographic progression of HOA [7]

Objectives

Methods

Results

Discussion

Conclusion