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Updated: Sep 28, 2025
Novel Mini-open Transforaminal Lumbar Interbody Fusion
Published on: June 6, 2025
Hounsfield Unit as a Predictor of Adjacent-Level Disease in Lumbar Interbody Fusion Surgery
Frank De Stefano1, Turki Elarjani2, Tyler Warner3
1School of Medicine, Kansas City University, Kansas City, Missouri, USA.
Insights
Lower preoperative Hounsfield units (HUs) in patients undergoing spinal fusion predict the need for future surgery due to adjacent segment disease. This finding highlights HUs as a valuable indicator for surgical planning and patient outcomes.
Area of Science:
- Spine Surgery
- Radiology
- Orthopedics
Background:
- Bone density is crucial for successful spinal fusion.
- Hounsfield units (HUs) on CT scans serve as an indirect measure of bone density.
- Low preoperative HUs may indicate underlying systemic disease and predict reoperation needs.
Purpose of the Study:
- To investigate the association between preoperative Hounsfield units (HUs) and the development of adjacent segment disease requiring surgical intervention after lumbar interbody fusion.
- To determine if HUs can predict the need for reoperation in spinal fusion patients.
Main Methods:
- Retrospective review of 793 patients who underwent lumbar interbody fusion between 2007 and 2016.
- Measurement of preoperative computed tomography (CT) Hounsfield units (HUs) from sagittal views of the vertebral body.
- Analysis of patient follow-up data to identify cases of adjacent segment disease requiring surgical intervention.
Main Results:
- Patients who did not require reoperation for adjacent segment disease had significantly higher mean preoperative HUs (180.7 ± 70.0) compared to those who did (148.4 ± 8.1).
- Preoperative CT Hounsfield units (HUs) were identified as a significant independent predictor for adjacent-level surgery after spinal arthrodesis (OR = 0.891).
Conclusions:
- Higher preoperative Hounsfield units (HUs) are associated with a lower likelihood of requiring reoperation for adjacent segment disease after lumbar interbody fusion.
- Preoperative CT HUs are a valuable predictive tool for identifying patients at higher risk of adjacent segment disease and subsequent surgical intervention.
Background:
Bone density has been associated with a successful fusion rate in spine surgery. Hounsfield units (HUs) have more recently been evaluated as an indirect representation of bone density. Low preoperative HUs may be an early indicator of global disease and chronic process and, therefore, indicative of the need for future reoperation.
Objective:
To assess preoperative HUs and their association with future adjacent segment disease requiring surgical intervention through retrospective study.
Methods:
Patients who underwent lumbar interbody fusion at a single institution between 2007 and 2016 were retrospectively reviewed. Hounsfield unit values were measured from preoperative computed tomography (CT) using sagittal images, encircling cancellous portion of the vertebral body. Patient charts were reviewed for follow-up data and adjacent-level disease development.
Results:
A total of 793 patients (age: 56.1 ± 13.7 years, 54.4% female) were included in this study. Twenty-two patients required surgical intervention for adjacent segment disease. Patients who underwent lumbar interbody fusion and did not subsequently require surgical intervention for adjacent-level disease were found to have a higher mean preoperative HU than patients who did require reoperation (180.7 ± 70.0 vs 148.4 ± 8.1, P = .032). Preoperative CT HU was a significant independent predictor for the requirement of adjacent-level surgery after spinal arthrodesis (odds ratio = 0.891 [0.883-0.899], P = .029).
Conclusion:
Patients who underwent lumbar interbody fusion that did not require reoperation for adjacent-level degeneration were found to have a higher mean preoperative HU than patients who did require surgical intervention. Lower preoperative CT HU was a significant independent predictor for the requirement of adjacent-level surgery after spinal arthrodesis.
