Correlation Between Rod Fracture and Shear Stress: A Novel Parameter

Authors

• Seth Street, University of Cincinnati College of Medicine
• Abhijith V. Matur, University of Cincinnati College of Medicine
• Xu Tao, University of Cincinnati College of Medicine
• Geet Shukla, University of Cincinnati College of Medicine
• Julia Garcia-Vargas, University of Cincinnati College of Medicine
• Jay P. Mehta, University of Cincinnati
• Kelly Childress, University of Cincinnati College of Medicine
• Justin Gibson, University of Cincinnati College of Medicine
• Daryn Cass, University of Cincinnati College of Medicine
• Andrew Wu, University of Cincinnati College of Medicine
• Henry Ofori Duah, Marquette UniversityFollow
• Benjamin Motley, University of Cincinnati College of Medicine
• Daniel Webb, University of Cincinnati College of Medicine
• Joseph Cheng, University of Cincinnati College of Medicine
• Owoicho Adogwa, University of Cincinnati College of Medicine

Document Type

Article

Publication Date

3-2024

Publisher

Elsevier

Source Publication

World Neurosurgery

Source ISSN

1878-8750

Abstract

Background We sought to assess the accuracy of a novel parameter proportional to the rod shear stress (RSS) in identifying patients at risk of rod fracture (RF) after surgery for correction of adult spinal deformity. Methods We performed a retrospective medical record review of patients aged ≥18 years treated for adult spinal deformity between 2004 and 2014 with ≥24 months of follow-up. The primary outcome was RFs identified radiographically. Patient weight (w), number of instrumented levels (N), and minimum rod diameter (d) were recorded and used to calculate the RSS parameter (). Receiver operating characteristic curves were produced and the area under the curve (AUC ± 95% confidence interval [CI]) was calculated to compare this parameter's discriminative accuracy to that of its constituent variables. The sensitivity, specificity, and likelihood ratios (LRs) were calculated. Results A total of 28 RF-positive and 154 RF-negative patients were included. The average age was 59.2 ± 9.6 years, and 93.4% were women. The RSS parameter produced the greatest AUC (0.73 ± 0.11). At an RSS cutoff of 30.1, it achieved a sensitivity of 71.4% and specificity of 71.4% (LR, 2.5; 95% CI, 1.8–3.5). The number of instrumented levels produced the next-greatest AUC (0.65 ± 0.12), with a sensitivity of 78.6% and specificity of 50.0% at a cutoff of 15 (LR, 1.6; 95% CI, 1.2–2.0). Conclusions The RSS is calculated using easily obtainable information and shows potential as a tool for predicting patient-specific risk of RF after spinal fusion. The number of instrumented levels also correlates strongly with the occurrence of RFs and is not significantly less accurate than the RSS. A larger sample size and prospective validation would be useful in determining with greater confidence which parameter is superior for predicting RFs after spinal fusion.

Comments

Accepted version. World Neurosurgery, Vol. 183 (March 2024): e268-e275. DOI. © 2024 Elsevier. Used with permission.

Henry O. Duah was affiliated with University of Cincinnati College of Nursing at time of publication.

Recommended Citation

Street, Seth; Matur, Abhijith V.; Tao, Xu; Shukla, Geet; Garcia-Vargas, Julia; Mehta, Jay P.; Childress, Kelly; Gibson, Justin; Cass, Daryn; Wu, Andrew; Duah, Henry Ofori; Motley, Benjamin; Webb, Daniel; Cheng, Joseph; and Adogwa, Owoicho, "Correlation Between Rod Fracture and Shear Stress: A Novel Parameter" (2024). College of Nursing Faculty Research and Publications. 1133.
https://epublications.marquette.edu/nursing_fac/1133