Correlation analysis of surgical outcomes and spino-pelvic parameters in patients with degenerative lumbar scoliosis

Objectives

The study aims to analyze factors that affect the postoperative health-related quality of life (HRQOL) of degenerative lumbar scoliosis (DLS) patients and explore the appropriate pelvic incidence minus lumbar lordosis (PI-LL) value for Chinese DLS patients.

Methods

DLS patients who met the inclusion and exclusion criteria were included in this study. General information, spino-pelvic parameters, and HRQOL were collected. Correlation analysis was used to explore the spino-pelvic parameters that affect the postoperative HRQOL. Thresholds of each parameter were obtained using the receiver operating characteristic (ROC) curve. Regardless of the effect of age, DLS patients were classified into three groups according to the SRS-Schwab classification: group 0 means PI-LL < 10°, group+means PI-LL = 10-20°, and group ++ means PI-LL > 20°. Postoperative HRQOL was analyzed using variance methods. The ROC curve was used to measure the appropriate PI-LL threshold. When considering the effect of age, the patients with Oswestry Disability Index (ODI) < 75% percentile were considered to have a satisfactory clinical outcome, which was drawn to an equation between PI-LL, age, and PI by multiple linear regression equation.

Results

A total of 71 patients were included. Compared with the control group, there were significant differences in both postoperative ODI and Scoliosis Research Society 22 (SRS-22) scores when the postoperative Cobb angle ≤11°, postoperative lumbar lordosis index (LLI) > 0.8, postoperative sagittal vertical axis (SVA) ≤ 5 cm, postoperative T1 pelvic angle (TPA) ≤ 16° and postoperative global tilt (GT) ≤ 22°, respectively. Regardless of the effect of age, there was a statistical difference in postoperative HRQOL between group 0 and group ++. The PI-LL threshold derived from the ROC curve was 14.4°. Compared with the PI-LL > 14° group, the PI-LL ≤ 14° group achieved a lower postoperative ODI score and a higher postoperative SRS-22 score. Considering the influence of age, the equation for ideal PI-LL was PI-LL = 0.52age + 0.38PI-39.4 (R = 0.509, p = 0.001).

Conclusions

PI-LL was an important parameter that affects the postoperative HRQOL of DLS patients. Sufficient LL should be restored during the operation (LL ≥ PI-14°). The appropriate PI-LL value was affected by age. Smaller LL needed to be restored as the age increased.

Measuring Muscle Activity in the Trunk, Pelvis, and Lower Limb Which Are Used to Maintain Standing Posture in Patients With Adult Spinal Deformity, With Focus on Muscles that Contract in the Compensatory Status

STUDY DESIGN

Prospective single-center study.

OBJECTIVE

This study aimed to investigate the muscle activity of the trunk, pelvis, and lower limb, which are used to maintain a standing posture in elderly patients with spinal deformities. We also elucidated the mechanism of compensation against spinal deformity in terms of muscle activity.

METHODS

Any patient scheduled to undergo surgery for adult spinal deformity was included. Surface electromyography and radiography were performed preoperatively. The following four representative alignments were defined as compensations: 1. pelvic retroversion, 2. reduction in thoracic kyphosis, 3. hyperextension of the lumbosacral junction, and 4. knee flexion. Individual muscle activity was compared with and without compensation. The patients were stratified into three groups according to the severity of spinal compensation, and differences in muscle activity were compared.

RESULTS

This study included 76 patients (7 men and 69 women, average age 69.4 years). Our results revealed that pelvic retroversion and knee flexion were compensations that required trunk muscle activity. In contrast, reduction of thoracic kyphosis and hyperextension of the lumbosacral junction did not require much trunk muscle activity. There was a significant difference in the muscle activity of the pelvis and lower limbs according to the severity of the deformity.

CONCLUSIONS

In terms of muscle activity, compensation for regional alignment changes in the adjacent spine is economical. However, extra-spinal compensations, such as pelvic retroversion and knee flexion, are non-economical. According to compensation recruitment, the muscle activity of the pelvis and lower limbs increased with the severity of the spinal deformity.

Modifications of spinopelvic parameters and acetabular orientation after spinal surgery for adult deformity in patient who underwent bilateral total hip arthroplasty

The spine and the hip are two anatomical districts that have close biomechanical relationship. The management of their degenerative disorders involves an in-depth biomechanical analysis of the patient, in order to define the proper hip-spine relation, using different biomechanical classifications that have been proposed in recent years. The changes in the spino-pelvic and acetabular parameters induced by prosthetic hip surgery and spinal surgery must be carefully evaluated, calculated and foreseen in the pre-operative phase, as they play a crucial role in defining the clinical success or failure of the operations. In this paper we present a case of a patient who underwent spinal surgery after a bilateral THA analyzing both spino-pelvic parameters and acetabular orientation and highlighting the strict relations between spine and hip.

Acetabular and spino-pelvic morphologies are different in subjects with symptomatic cam femoro-acetabular impingement

Acetabular and spino-pelvic (SP) morphological parameters are important determinants of hip joint dynamics. This prospective study aimed to determine whether acetabular and SP morphological differences exist between hips with and without cam morphology and between symptomatic and asymptomatic hips with cam morphology. A cohort of 67 patients/hips was studied. Hips were either asymptomatic with no cam (Controls, n = 18), symptomatic with cam (n = 26) or asymptomatic with cam (n = 23). CT-based quantitative assessments of femoral, acetabular, pelvic, and spino-pelvic parameters were performed. Measurements were compared between controls and those with a cam deformity, as well as between the three groups. Morphological parameters that were independent predictors of a symptomatic cam were determined using a regression analysis. Hips with cam deformity had slightly smaller subtended angles superior-anteriorly (87° vs. 84°, p = 0.04) and greater pelvic incidence (53° vs. 48°, p = 0.003) compared to controls. Symptomatic cams had greater acetabular version (p < 0.01), greater subtended angles superiorly and superior-posteriorly (p = 0.01), higher pelvic incidence (p = 0.02), greater alpha angles and lower femoral neck-shaft angles compared to asymptomatic cams (p < 0.01) and controls (p < 0.01). The four predictors of symptomatic cam included antero-superior alpha angle, femoral neck-shaft angle, acetabular depth, and pelvic incidence. In conclusion, this study illustrates that symptomatic hips had a greater amount of supero-posterior coverage; which would be the contact area between a radial cam and the acetabulum, when the hip is flexed to 90°. Furthermore, individuals with symptomatic cam morphology had greater PI. Acetabular- and SP parameters should be part of the radiological assessment of femoro-acetabular impingement. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1840-1848, 2018.

Numerical evaluation of the correlation between the normal variation in the sagittal alignment of the lumbar spine and the spinal loads

We present a numerical approach to reproduce various patterns of spino-pelvic organization. We wanted to predict the spinal loads in two static conditions (standing and holding a weight in the hands) based on parameters describing the shape of the lumbar spine: type following Roussouly classification, sacral slope, apex, inflection point and lumbar lordosis. Four hundred eighty finite element models including trunk muscles and representing the entire range of normal variability were created. The models predicted that, in the case of a moderate external load of 50 N, a lordotic and well balanced spine (e.g., type 3) could reduce the muscle activation in comparison with a more lordotic (type 4) spine, with negligible differences compared to a more straight spine (type 2). However, such a sagittal configuration was not correlated with a minimization of the loading state in the intervertebral discs, especially regarding anteroposterior shear loads. In the standing posture without any additional load, a less lordotic and more vertical spine (e.g., types 1 and 2) was sufficient to ensure a condition of minimal spinal loads. Despite a number of limitations, inverse statics numerical models of spine biomechanics including trunk muscles appear to be a promising tool to fill the knowledge gap between the clinical observations of the correlations between the spino-pelvic organization and the consequent spinal disorders.