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The Change in Sway and Neuromuscular Activity in Adult Degenerative Scoliosis Patients Pre and Post Surgery Compared With Controls

Haddas, Ram PhD; Lieberman, Isador H. MD, MBA, FRCSC

doi: 10.1097/BRS.0000000000003009

Study Design. Prospective cohort study.

Objective. The purpose of this study is to quantify the extent of change in sway associated with maintaining a balanced posture within the cone of economy (CoE), in a group of adult degenerative scoliosis (ADS) patients’ pre and postsurgery and compare them to matched non-scoliotic controls.

Summary of Background Data. Patients with spinal deformities adopt a variety of postural changes in the spine, pelvis, and lower extremities in their effort to compensate for the anterior shift in the gravity line. ADS patients are known to exhibit an increased sway within their CoE. Greater sway expends more energy while standing when compared with healthy controls. Spinal alignment surgery has been shown to improve sagittal vertical axis and balance.

Methods. Thirty-three ADS patients and performed a series of functional balance tests a week before and 3 months after surgery along with 20 non-scoliotic control.

Results. ADS patients demonstrated more initial CoM (P = 0.001) and head (P = 0.011) displacements. Postoperatively ADS patients exhibited less CoM sway (P = 0.043) and head sway (P = 0.050), in comparison to their presurgery measures. Postsurgical ADS patients demonstrated more CoM (P = 0.002) and head (P = 0.012) displacements and increased muscle activity in comparison to non-scoliotic controls.

Conclusion. Surgical alignment reduced the amount of sway, reduced the center of mass displacement, and reduced spine and lower extremity energy expenditure in ADS’ patients. In symptomatic preoperative ADS patients, sagittal sway increased along with greater lumbar spine and lower extremity neuromuscular activity in comparison to a non-scoliotic control. Although surgical alignment improved ADS functional parameters during a dynamic balance test, these parameters approached but did not fully achieve non-scoliotic control parameters when measured 3 months after surgery.

Level of Evidence: 3

We present a method that quantifies the dimensions of the cone of economy in a group of degenerative scoliosis patients compared with non-scoliotic controls. Surgical alignment reduced the amount of sway and overall displacement and reduced spine and lower extremity energy expenditure in adult degenerative scoliosis patients 3 months after surgical intervention.

Texas Back Institute, Plano, Texas.

Address correspondence and reprint requests to Dr. Ram Haddas, PhD, Texas Back Institute, 6020 West Parker Road, Plano, TX 75093; E-mail:

Received 30 July, 2018

Revised 2 January, 2019

Accepted 10 January, 2019

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

Relevant financial activities outside the submitted work: grants.

Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.