The New Munich Elbow Soft Tissue (MEST) classification is a reliable MRI-based injury severity grading system for acute simple elbow dislocations.
TL;DR
The MEST classification represents a comprehensive and reliable classification for injury patterns after acute SED, offering additional guidance in clinical decision-making and showed substantial to excellent intrarater reliability.
Abstract
Purpose
Simple elbow dislocation (SED) is characterized by injuries to soft tissue structures. The aim of the novel Munich Elbow Soft Tissue (MEST) classification is to provide a systematic approach to grade the severity of musculoligamentous lesions after acute SED. The purpose of this study is to determine the reliability of the classification.
Methods
All elbow dislocations between 1 January 2012 and 31 December 2024 that presented to a high-frequency, multilevel trauma centre were screened retrospectively for inclusion criteria. Patients with a history of elbow fractures, chronic instability, previous surgery, previous musculoligamentous injuries, time from injury to magnetic resonance imaging (MRI) > 30 days and a lack of or low-quality MRI imaging were excluded. In 30 randomly selected patients, injuries were classified according to the MEST system into Grade 1 (ligamentous) and Grade 2 (musculoligamentous), with an extended subclassification comprising eight subtypes based on detailed structure-specific MRI assessment. Inter- and intrarater reliability were evaluated using Fleiss' and Cohen's Kappa (κ).
Results
Of the randomly selected 30 patients (age 38.1 ± 13.4 years, male 46.7%), the mean time from injury to MRI was 4.2 ± 3.9 days. Interrater reliability across all raters demonstrated substantial agreement for the MEST grade (Fleiss' κ 0.690) and for the MEST subclassification (Fleiss' κ 0.639). Exact agreement was found in 70.0% for the MEST grade and in 43.3% for the MEST subclassification. Agreement between radiologists yielded higher agreement for the MEST subclassification than between the orthopaedics, and vice versa for the MEST grade. The less experienced raters showed higher agreement than the experienced raters. The classification also showed substantial to excellent intrarater reliability, with mean κ values of 0.900 for the MEST grade and 0.800 for the MEST subclassification.
Conclusion
The MEST classification represents a comprehensive and reliable classification for injury patterns after acute SED, offering additional guidance in clinical decision-making. LEVEL OF EVIDENCE Level IV.