The Use of Distal Ulnar Hounsfield Units to Predict Future Fragility Fracture Risk

Theodora C Dworak; Scott C Wagner; Kyle E Nappo; George C Balazs; Patrick D Grimm; Donald F Colantonio; Scott M Tintle

doi:10.1016/j.jhsa.2018.04.017

The Use of Distal Ulnar Hounsfield Units to Predict Future Fragility Fracture Risk

J Hand Surg Am. 2018 Nov;43(11):1010-1015. doi: 10.1016/j.jhsa.2018.04.017. Epub 2018 Jun 8.

Authors

Theodora C Dworak¹, Scott C Wagner², Kyle E Nappo¹, George C Balazs¹, Patrick D Grimm¹, Donald F Colantonio³, Scott M Tintle⁴

Affiliations

¹ Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, MD; Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD.
² Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, MD; Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD; Department of Orthopaedics, Rothman Institute at Thomas Jefferson University, Philadelphia, PA. Electronic address: cameron.wagner@gmail.com.
³ Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD.
⁴ Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, MD; Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD; Department of Orthopaedic Surgery, University of Pennsylvania Health System, Philadelphia, PA.

PMID: 29891269
DOI: 10.1016/j.jhsa.2018.04.017

Abstract

Purpose: Distal ulnar Hounsfield unit (HU) measurements obtained from computed tomography (CT) scans of the wrist can be used to accurately screen for low bone mineral density. It is unknown whether HU measurements can also predict the risk of future fragility fractures. Therefore, the purpose of this study was to determine if the HU values of the distal ulna correlate to fragility fracture risk.

Methods: An electronic database of radiographs at a single institution was searched for all wrist CT scans, obtained for any reason, between January 1, 2002, and December 31, 2008, to allow a minimum of 5-year follow-up. Manual measurement of HU on sequential coronal CT slices of the distal ulnar head was taken, and mean values were recorded. Previously determined cutoff values for the diagnosis of low bone mineral density were implemented to stratify patients as at risk or not at risk for future fragility fracture. Medical records were then manually reviewed for the occurrence of any future fragility fracture (hip, spine, proximal humerus, or rib).

Results: There were 161 CTs in 157 patients and 34 fragility fractures in 21 patients, with a prevalence of 13.4%. The mean HU in the fragility fracture group was significantly lower (134.2 vs 197.1 HU). The percentage of low HU patients with fragility fractures was significantly higher (22.7% vs 3.8%). The odds ratio for fragility fracture in the low HU group was 7.4 (95% confidence interval, 2.1-26.2). Using previously determined cutoff values, the sensitivity and specificity of distal ulna HU values for identifying patients who would sustain at least 1 future fragility fracture were 85.7% and 55.2%, respectively.

Conclusions: Patients with low distal ulnar HU were significantly more likely to sustain a subsequent fragility fracture. A determination of distal ulnar HUs represents a quick, simple tool to identify patients potentially at risk for fragility fractures.

Type of study/level of evidence: Prognostic IV.

Keywords: Hounsfield unit; Wrist computed tomography; fragility fracture; screening test.

MeSH terms

Bone Density*
Female
Follow-Up Studies
Humans
Male
Middle Aged
Osteoporosis / diagnostic imaging*
Osteoporotic Fractures / epidemiology*
Osteoporotic Fractures / etiology
Risk Assessment*
Sensitivity and Specificity
Tomography, X-Ray Computed*
Ulna / diagnostic imaging*