Defining normal joint space width in essential joints of the foot and ankle using an objective weight bearing CT hounsfield unit algorithm

Hannah J. Zeller; Donald D. Anderson; Tutku Tazegul; Ryan Jasper; Vineel Mallavarapu; Matthew Jones; Kepler Alencar Mendes De Carvalho; Nacime Salomao Barbachan Mansur; Cesar de Cesar Netto

doi:10.1016/j.fas.2026.02.001

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Defining normal joint space width in essential joints of the foot and ankle using an objective weight bearing CT hounsfield unit algorithm

Journal article

Peer reviewed

Defining normal joint space width in essential joints of the foot and ankle using an objective weight bearing CT hounsfield unit algorithm

Hannah J. Zeller, Donald D. Anderson, Tutku Tazegul, Ryan Jasper, Vineel Mallavarapu, Matthew Jones, Kepler Alencar Mendes De Carvalho, Nacime Salomao Barbachan Mansur and Cesar de Cesar Netto

Foot and ankle surgery

02/17/2026

DOI: 10.1016/j.fas.2026.02.001

PMID: 41708422

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Abstract

The tibiotalar (TT), subtalar (ST), talonavicular (TN), and first metatarsophalangeal (MTP) joints of the foot and ankle are essential for foot mobility and function. Assessing progression of osteoarthritis (OA) in these joints involves subjective radiographic grading that lacks reliability and reproducibility. The purpose of this prospective comparative study was to define normal articular features and joint space width (JSW) in four joints of the foot and ankle using objective analysis of weight-being CT (WBCT) intensity profiles in healthy, non-arthritic subjects. This was a cross-sectional IRB-approved study (ID #201904825) where bilateral WBCT scans of the foot and ankle were performed in 20 healthy subjects (40 feet, 9 females, 11 males) with no clinical or radiographic evidence of OA, bony abnormalities, or foot deformities. Five parallel linear spatial projections were generated across the joint space to measure WBCT intensities extending from subchondral bone, to cartilage, through the joint space, then to opposing cartilage and subchondral bone. The software graphically plotted WBCT intensity profiles of these projections which were then interpreted to measure the joint space width (JSW) and Michelson contrast of Hounsfield unit (HU) intensities, two relevant metrics of joint preservation, for each joint. The average JSW for healthy TT, ST, TN, and first MTP joints were 3.97 (95 % CI 3.73 – 4.20), 4.20 (3.96 – 4.44), 3.33 (3.07 – 3.58), and 3.87 (3.64 – 4.12) mm, respectively. The average Michelson contrast was 71.8 (95 % CI 67.32 – 76.26), 92.5 (87.82 – 97.08), 84.1 (79.25 – 88.85), and 101.4 (96.87 – 105.81), respectively. We utilized a novel 3D analysis of WBCT intensity profiles to assess normal JSW and HU intensities in four joints of the foot and ankle to provide a foundation for future work developing an objective grading system for osteoarthritis.

Arthritis

Osteoarthritis

Ankle

Joint space width

Kellgren-Lawrence

OA Classification

Weight bearing CT

Details

Title: Subtitle: Defining normal joint space width in essential joints of the foot and ankle using an objective weight bearing CT hounsfield unit algorithm
Creators: Hannah J. Zeller - University of Iowa
Donald D. Anderson - University of Iowa
Tutku Tazegul - University of Iowa
Ryan Jasper - University of Iowa
Vineel Mallavarapu - University of Iowa
Matthew Jones - University of Iowa
Kepler Alencar Mendes De Carvalho - University of Iowa, Orthopedics and Rehabilitation
Nacime Salomao Barbachan Mansur - University of Iowa, Orthopedics and Rehabilitation
Cesar de Cesar Netto - University of Iowa
Resource Type: Journal article
Publication Details: Foot and ankle surgery
DOI: 10.1016/j.fas.2026.02.001
PMID: 41708422
NLM abbreviation: Foot Ankle Surg
ISSN: 1268-7731
eISSN: 1460-9584
Publisher: Elsevier Ltd
Language: English
Electronic publication date: 02/17/2026
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Orthopedics and Rehabilitation; Industrial and Systems Engineering
Record Identifier: 9985139490802771

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