Reciprocal Changes in the Whole-Body Following Realignment Surgery in Adult Spinal Deformity

Abstract

The idea of the global balance of spine stems from Jean Dubousset, who first introduced the concept of cone of economy. Through the compensatory mechanisms, the human body maintains an upright posture and horizontal gaze in the setting of the spinal malalignment. Compensation takes place not only in the mobile spine segments, but also in the pelvis and lower extremities. Patients with a malalignment exhibit compensatory changes in the cervical hyper-lordosis, posterior pelvic shift, knee/ankle flexion, hip extension, and the pelvic retroversion. The advent of whole-body stereo radiography has yielded an improved understanding of global changes among the patients. Deformity-induced compensatory changes in the sagittal alignment could be resolved reciprocally after the surgical correction of the malalignment. Thoracolumbar realignment surgery restores the pathologic compensatory changes in the unfused spinal segments, pelvis, and the lower extremities. Similarly, reciprocal changes in the thoracolumbar spine may harmonize global sagittal alignment after the cervical reconstruction. This study reviews the compensatory mechanisms and reciprocal changes in global sagittal alignment caused by the surgical correction and highlights, the factors that should be considered while assessing a patient’s compensatory status.

Biomechanical Comparison of Multilevel Lumbar Instrumented Fusions in Adult Spinal Deformity According to the Upper and Lower Fusion Levels: A Finite Element Analysis

“…Previously, conservative management was recommended owing to higher morbidity associated with surgery [2]; however, surgical intervention with multilevel lumbar fusion has become the mainstay of adult spinal deformity treatment recently [4]. Numerous literatures have reported the superiority of multilevel lumbar fusion for the treatment of various types of adult spinal deformity [1,[5][6][7][8][9].…”

Reciprocal Changes Following Cervical Realignment Surgery

“…The EOS system was developed to overcome the limitations of conventional radiography by interdisciplinary investigators. 1 Using the 3-dimensional bone external envelope technique, EOS allows bilateral long-length images (whole-body or localized) in either the standing or seated position, with overall enhanced image quality and a lower radiation dose for the patient. 35,36 Through whole-body radiographs, our understanding of the global balance and reciprocal changes in the cervical spine and the lower extremities became more profound.…”

“…Through full-body stereoradiography, the understanding of compensatory mechanisms in patients with spinopelvic imbalance has progressed rapidly, and the concept of global balance and reciprocal change has expanded to the field of the cervical spine and lower extremities. 1 The regions of the spine are intertwined through compensatory mechanisms. When a patient loses an adequate lumbar lordosis (LL), compensatory mechanisms are recruited to maintain an upright posture; cervical hyperlordosis, thoracic kyphosis (TK), pelvic retroversion, and knee flexion.…”

Clinical Impact and Correlations of Odontoid Parameters Following Multilevel Posterior Cervical Fusion Surgery

“…The idea of optimal alignment of the thoracolumbar spine is well-established, and pelvic parameters are the foundation of sagittal alignment of the spine. 1 A mismatch greater than 9° between pelvic incidence (PI) and lumbar lordosis (LL) is a signifi-cant predictor of disability. 2,3 Accordingly, numerous attempts have been made using various parameters to define optimal cervical alignment.…”

“…Over the last few decades, the concept of sagittal spinal alignment in the thoracolumbar spine has been extensively studied. The idea of optimal alignment of the thoracolumbar spine is well-established, and pelvic parameters are the foundation of sagittal alignment of the spine [ 1 ]. A mismatch greater than 9° between pelvic incidence (PI) and lumbar lordosis (LL) is a significant predictor of disability [ 2 , 3 ].…”