Quantifying the Contribution of Lower Limb Compensation to Upright Posture: What Happens if Adult Spinal Deformity Patients Do Not Compensate?

Abstract

Study design

This is a multicenter, prospective cohort study.

Objective

This study tests the hypothesis that elimination of lower limb compensation in patients with adult spinal deformity (ASD) will significantly increase the magnitude of sagittal malalignment.

Summary of background data

ASD affects a significant proportion of the elderly population, impairing functional sagittal alignment and inhibiting overall quality of life. To counteract these effects, patients with ASD use their spine, pelvis, and lower limbs to create a compensatory posture that allows for standing and mobility. However, the degree to which each of the hips, knees, and ankles contributes to these compensatory mechanisms has yet to be determined.

Methods

Patients undergoing corrective surgery for ASD were included if they met at least one of the following criteria: complex surgical procedure, geriatric deformity surgery, or severe radiographic deformity. Preoperative full-body x-rays were evaluated, and age and PI-adjusted normative values were used to model spine alignment based upon three positions: compensated (all lower extremity compensatory mechanisms maintained), partially compensated (removal of ankle dorsiflexion and knee flexion, with maintained hip extension), and uncompensated (ankle, knee, and hip compensation set to the age and PI norms).

Results

288 patients were included (mean age 60 y, 70.5% females). As the model transitioned from the compensated to uncompensated position, initial posterior translation of the pelvis decreased significantly to an anterior translation versus the ankle (P.Shift: 30 to -7.6 mm). This was associated with a decrease in pelvic retroversion (PT: 24.1 to 16.1), hip extension (SFA: 203 to 200), knee flexion (KA: 5.5 to-0.4), and ankle dorsiflexion (AA: 5.3 to 3.7). As a result, the anterior malalignment of the trunk significantly increased: SVA (65 to 120 mm) and G-SVA (C7-Ankle from 36 to 127 mm).

Conclusion

Removal of lower limbs compensation revealed an unsustainable truncal malalignment with two-fold greater SVA.

Department

Description

Provenance

Citation

Published Version (Please cite this version)

10.1097/brs.0000000000004646

Publication Info

Lafage, Renaud, Priya Duvvuri, Jonathan Elysee, Bassel Diebo, Shay Bess, Douglas Burton, Alan Daniels, Munish Gupta, et al. (2023). Quantifying the Contribution of Lower Limb Compensation to Upright Posture: What Happens if Adult Spinal Deformity Patients Do Not Compensate?. Spine, Publish Ahead of Print. 10.1097/brs.0000000000004646 Retrieved from https://hdl.handle.net/10161/27958.

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Scholars@Duke

Peter Passias

Instructor in the Department of Orthopaedic Surgery
Shaffrey

Christopher Ignatius Shaffrey

Professor of Orthopaedic Surgery

I have more than 25 years of experience treating patients of all ages with spinal disorders. I have had an interest in the management of spinal disorders since starting my medical education. I performed residencies in both orthopaedic surgery and neurosurgery to gain a comprehensive understanding of the entire range of spinal disorders. My goal has been to find innovative ways to manage the range of spinal conditions, straightforward to complex. I have a focus on managing patients with complex spinal disorders. My patient evaluation and management philosophy is to provide engaged, compassionate care that focuses on providing the simplest and least aggressive treatment option for a particular condition. In many cases, non-operative treatment options exist to improve a patient’s symptoms. I have been actively engaged in clinical research to find the best ways to manage spinal disorders in order to achieve better results with fewer complications.


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