In imaging diagnostics, classification schemes are very common. As far as osteoarthritis is concerned, the Kellgren classification is the most popular. However, the Kellgren classification, which has been used for more than 50 years, is based on nonspecific criteria; thus, high interobserver variability has been reported. In addition, the Kellgren classifications have not been coordinated with magnetic resonance imaging (MRI)-based classification schemes, e.g., Vallotton.
In this paper, we present some modifications concerning the criteria for both the Kellgren classification and its comparison with the MRI-based Vallotton classification.
The current surgical and imaging classifications and the precision of the nomenclature are analyzed. X‑ray and MRI findings are compared.
Suggestions for both a modification of the Kellgren classification as far as the criteria are concerned and a hierarchy (ranking) of X‑ray and MRI findings to make clinical decisions more valuable are proposed.
These proposed modifications (Kellgren and ranking) would be helpful for routine reporting and allow for better interobserver reliability, in particular for special reports (e.g. consultations, expert opinions, advanced diagnostics).