Faculty Collaboration Database

A Patient-specific Approach to Alignment and Proximal Junctional Kyphosis Risk Assessment in Adult Spinal Deformity Surgery: Development and Validation of a Predictive Tool. Clin Spine Surg 2022 Jul 01;35(6):256-263

Date

01/17/2022

Pubmed ID

35034047

DOI

10.1097/BSD.0000000000001296

Scopus ID

2-s2.0-85124092506 (requires institutional sign-in at Scopus site)   6 Citations

Abstract

STUDY DESIGN: This was a single-institution, retrospective cohort study.

OBJECTIVE: We aimed to develop a predictive model for proximal junctional kyphosis (PJK) severity that considers multiple preoperative variables and modifiable surgical alignment.

SUMMARY OF BACKGROUND DATA: PJK is a common complication following adult deformity surgery. Current alignment targets account for age and pelvic incidence but not other risk factors.

MATERIALS AND METHODS: This is a single-institution, retrospective cohort study of adult deformity patients with a minimum 2-year follow-up undergoing instrumented fusion between 2009 and 2018. A proportional odds regression model was fit to estimate PJK probability and Hart-International Spine Study Group (ISSG) PJK severity score. Predictors included preoperative Charlson Comorbidity Index, vertebral Hounsfield Units near the upper instrumented vertebrae, pelvic incidence, T1-pelvic angle, and postoperative L1-L4 and L4-S1 lordosis. Predictor effects were assessed using adjusted odds ratios and a nomogram constructed for estimating PJK probability. Bootstrap resampling was used for internal validation.

RESULTS: Of 145 patients, 47 (32%) developed PJK. The median PJK severity score was 6 (interquartile range, 4-7.5). After adjusting for predictors, Charlson Comorbidity Index, Hounsfield Units, preoperative T1-pelvic angle, and postoperative L1-L4 and L4-S1 lordosis were significantly associated with PJK severity ( P <0.05). After adjusting for potential overfitting, the model showed acceptable discrimination [ C -statistic (area under the curve)=0.75] and accuracy (Brier score=0.10).

CONCLUSIONS: We developed a model to predict PJK probability, adjusted for preoperative alignment, comorbidity burden, vertebral bone density, and modifiable postoperative L1-L4 and L4-S1 lordosis. This approach may help surgeons assess the patient-specific risk of developing PJK and provide a framework for future predictive models assessing PJK risk after adult deformity surgery.

LEVEL OF EVIDENCE: Level III.

Author List

Hills JM, Weisenthal BM, Wanner JP, Gupta R, Steinle A, Pennings JS, Stephens BF

Author

John P. Wanner MD Assistant Professor in the Orthopaedic Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adult
Humans
Kyphosis
Lordosis
Postoperative Complications
Retrospective Studies
Risk Assessment
Risk Factors
Spinal Fusion