Pre to Postoperative Degree and Shape of Thoracic Kyphosis in Adult Spinal Deformity

Thursday, June 1, 2023

8:30 AM – 6:15 PM

Location: Salons 7-8

Presenting Author (Person doing the Podium Present(s)

RL

Renaud Lafage, MS

Senior Biomedical engineer
Lenox Hill Hospital
new york, New York, United States

Co-Author(s)

BD

Bassel Diebo, MD

Spine Surgeon
Brown University
Brooklyn, Rhode Island, United States
AD

Alan H. Daniels, MD

Chief, Spine Surgery
Brown University
East Providence, RI, United States
PP

Peter G. Passias, M.D.

Spine Surgeon
NYU Langone Orthopedic Hospital
New York, New York, United States
CA

Christopher Ames

United States
SB

Shay Bess, M.D.

Spine surgeon
Denver International Spine Center
castle rock, Colorado, United States
Robert K. Eastlack, M.D.

Partner, Spine Section, Division of Orthopaedic Surgery
Scripps Clinic
La Jolla, California, United States
MG

Munish C. Gupta, MD

M. B. Simon Distinguished Professor of Orthopaedic Surgery, Professor of Neurological Surgery
Washington University School of Medicine, St. Louis, USA
St. Louis, Missouri, United States
RH

Richard Hostin, MD

Medical Director
Southwest Scoliosis Institute
Plano, Texas, United States
KK

Khaled M. Kebaish

Johns Hopkins University, Maryland, United States
HK

Han Jo Kim, MD

Surgeon
Hospital for Special Surgery
New York, New York, United States
EK

Eric Klineberg, MD

Professor/ Vice Chair Dept or Orthopaedic Surgery
University of CA, Davis
Sacramento, California, United States
Gregory M. Mundis, Jr., M.D.

Director San Diego Spine Fellowship
Scripps Clinic
Encinitas, California, United States
JS

Justin Smith, MD, PhD

University of Virginia
Charlottesville, Virginia, United States
CS

Christopher I. Shaffrey, Sr., MD

Duke University Medical Center
Durham, North Carolina, United States
FS

Frank Schwab, MD

Lenox Hill Hospital, Northwell Health
New York, New York, United States
Virginie Lafage, PhD

AVP, Clinical Research
Lenox Hill | Northwell
Hospital for Special Surgery
New York, New York, United States

View E-Poster
DB

Douglas Burton, MD

Department Chair, Orthopedic Surgery and Sports Medicine
University of Kansas Medical Center
Kansas City, Kansas, United States
II

International Spine Study Group Foundation ISSGF

na
ISSGF
Brighton, Colorado, United States

Submitter(s)

Virginie Lafage, PhD

AVP, Clinical Research
Lenox Hill | Northwell
Hospital for Special Surgery
New York, New York, United States

View E-Poster

Disclosure(s):

Peter G. Passias, M.D.: No relevant disclosure to display

Robert K. Eastlack, M.D.: No relevant disclosure to display

Introduction:
Sagittal plane analysis for Adult Spinal Deformity (ASD) tends to focus on lumbar lordosis. As such, little is known about the baseline shape of thoracic kyphosis (TK) and the optimal versus iatrogenic impact of long fusions on this curvature.

AIMS/

Objectives:
To investigate the shape of TK before and after fusion among ASD patients treated with long fusion.

Methods:
In this registry based analysis, ASD patients undergoing posterior spinal fusions from at least T5 to L1 without prior fusion extending to the thoracic spine were included. Patients were categorized based on the preoperative T1-T12 kyphosis into: Hypo TK (if < 30°), Normal TK, and Hyper TK (if >70°), using published normative data. Values of regional Kyphosis at T10-L1 (Distal), T5-T10 (Middle), and T1-T5 (Proximal) and their relative contribution to total kyphosis were compared between groups. In each TK group, pre to postoperative TK changes were investigated using paired t-Test. Rates of patients converting from one group to another were reported.

Results:
329 surgical ASD (mean age: 57±16, 79.6% F) were analyzed. Pre-op T1-T12 TK for the entire cohort was 40.9±2°. Before surgery, 106 (32.2%) patients had HypoTK (mean: 15.8±8°), 187 (56.8%) had normal TK (47.4±11°), and 36 (10.9%) presented with HyperTK (81.5±12.5°). Distal and middle kyphosis differed significantly across TK groups, with HypoTK having the smallest distal T10-L1 TK (5.9 vs. 17.1 & 26.0), and the smalled T5-T10 Middle TK (8 vs. 25.3 & 45.4). The percentage of contribution to total kyphosis was not significantly different (Distal: 24.1% vs. 34.1% vs. 32.8%; Middle: 46.6% vs. 53.9% vs .56.8% all p>0.1).

Postoperatively, T1-12 TK increased significantly (40.9±2° vs. 57.8±17.6). Spinal fusion changed the shape/degree of TK in each group: 77.4% of baseline HypoTK and 38.9% of HyperTK patients corrected to a normal TK (between 30 and 70°). However, 29.9% of patients with normal TK at baseline had iatrogenic HyperTK postoperatively (54.5±10.8 to 79.4±6.5). Each group had a decrease in distal kyphosis (HypoTK 2.6±10.4; NormalTK 8.9±11.5; HyperTK 14.9±12, all p< 0.05). The Middle kyphosis significantly decreased for Hyper TK (11.8±12.4) and increased for both Normal TK and Hypo TK (3.8±11 and 14.2±11). Proximal TK increased significantly for all groups by 14 to 18°. Segmentally, HyperTK patients had a significant decrease in kyphosis at every level below T6-7; most of the correction occurred at T10-11 (5°) and T11-12 (6°). HypoTK had the opposite, with a significant increase in kyphosis for every level above T11-12. Normal TK patients experienced no significant change between T7 and T10, but the cephalad levels increased in kyphosis while caudal levels decrease in kyphosis.

Conclusions:
Posterior spinal fusion for ASD alters the degree and shape of thoracic kyphosis. While 60% of patients had a normal TK at baseline, 30% of those had iatrogenic hyperkyphosis postoperatively. Patients with baseline hypokyphosis were more likely to be corrected to normal TK than hyperkyphotic patients. Future research should investigate TK restoration in ASD and its impact on clinical outcomes and complications.