Absolute and Relative Agreement Between Radiographic and Sonographic Calcaneal Ossification Staging: A Pilot Study

Abstract

Background:

Radiographic evaluations are commonly used to determine calcaneal ossification staging throughout pediatric development. Sonographic imaging may offer a less expensive, noninvasive, clinically feasible option for calcaneal developmental assessments. Here, we assessed (1) inter-rater agreement of radiographic and sonographic calcaneal ossification staging of children and adolescent patients with Sever’s disease and (2) agreement between radiographic and sonographic calcaneal ossification staging scores.

Hypothesis:

There would be substantial agreement of radiographic and sonographic calcaneal ossification staging across raters, and between imaging measures.

Study Design:

Retrospective cohort study.

Level of Evidence:

Level 3.

Methods:

Adolescent patients (<18 years of age) with physician-diagnosed Sever’s disease who had complete calcaneal sonographic and radiographic imaging available on a retrospective chart review were included. Three independent reviewers with advanced training in musculoskeletal ultrasound each separately assessed radiographic and sonographic imaging data and assigned calcaneal calcification stages (0-5) to blinded images based on established criteria. Fleiss’ Kappa analyses were used to determine inter-rater staging agreement for both imaging approaches. Cohen’s Kappa analyses were used to determine the agreement between radiographic and sonographic staging. Absolute agreement, and relative agreement within each stage were assessed for both analyses.

Results:

Data from 19 patients (13 female, 6 male; 12.2 ± 2.3 years) were included. Absolute inter-rater agreement for radiographic and sonographic calcaneal ossification staging was comparable across the 3 raters (radiographs, κ = 0.692, z = 9.02; P < .01; sonographs, κ = 0.713, z = 7.95; P < .01), and perfect relative agreement (κ = 1.0, z = 10.6; P < .01). Consensus scores for radiographic and sonographic staging had moderate (κ = 0.535, z = 4.2; P < .01, and perfect relative (100% relative agreement, z = 6.22; P < .01) agreement.

Conclusion:

Sonographic evaluations of calcaneal ossification staging was comparable across assessors, and similar to radiographic staging.

Clinical Relevance:

Clinicians may consider incorporating ultrasound imaging for calcaneal ossification staging for young patients.