Forensic age assessment of the knee: proposal of a new classification system using two-dimensional ultrasound volumes and comparison to MRI

Jochen Herrmann,Markus Auf Der Mauer,Michael Groth,Eilin Jopp-Van Well,Dennis Säring

doi:10.1007/s00330-020-07343-1

Abstract

ObjectivesTo assess epiphyseal growth plate closure of the knee for forensic age estimation using an ultrasound (US)-based method and to compare the findings with MRI.MethodsThirty-three healthy male individuals (age, 14.4–19.3 years) were prospectively evaluated for epiphyseal growth plate closure of the right knee by recordings of two-dimensional US volumes and a high-resolution T1-weighted MRI sequence. The degree of epiphyseal growth plate closure was rated independently by two readers for each method using a modality specific three-point scale that differentiates between an open physis (S1), a partially closed physis (S2), and a closed physis (S3).ResultsThe inter-rater agreement was high for the US (Cohen’s kappa (CK): femur 95.2%, tibia 81.3%, fibula 86.3%) and the MRI method (CK: femur 70.2%, tibia 90.8%, fibula 79.8%). The degree of growth plate closure associated positively with advancing age. The US system showed a clearer separation of median ages with lower overlap than the MRI system. Open growth plates on minors (< S3 on femur and tibia) were identified by US with higher sensitivity (1.0 vs. 0.7) and slightly lower specificity (0.7 vs. 0.85) compared with MRI. The examination time was substantially shorter on US than on MRI (2.65 ± 0.91 min vs. 24.72 ± 2.72 min; p < 0.001).ConclusionsThe US method for evaluation of growth plate closure of the knee can reliably assign male individuals to different ossification stages and identifies minors with high accuracy. More studies with larger numbers are needed to further evaluate this method.Key Points• US is feasible to determine the degree of epiphyseal growth plate closure of the knee, shows a high degree of reliability, and is comparable to MRI.• US of the knee can detect open growth plates on male minors with high accuracy.• US of the knee may be used as a fast, non-invasive imaging tool for forensic age estimation to identify male minors.

Highlights

Age estimation in forensic medicine has gained increasing importance since the 1990s due to high levels of immigration into Europe and is an element of foreigner, asylum, and criminal law [1]
This work investigated the feasibility of an US-based method for forensic age estimation and compared the findings with Magnetic resonance imaging (MRI)
The US grading system is closely related to the MRI-based classification system of the knee used for age determination previously published by Jopp et al [35, 62]

Summary

Introduction

Age estimation in forensic medicine has gained increasing importance since the 1990s due to high levels of immigration into Europe and is an element of foreigner, asylum, and criminal law [1]. Age assessment has to be safeguarded in the best interest of the potential child. If the age of an individual cannot be determined by non-medical methods alone, medical imaging may be used in accordance with the local legal provisions beginning with an x-ray of the left hand or a dental view. A computer tomography (CT) of the clavicles is recommended to specify an age > 18 years [5]. The application of ionizing radiation for non-medical purposes has been criticized due to its potentially harmful effects [4] and due to the availability of alternative radiation-free methods

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