Healing of Radiologic Damage in Rheumatoid Arthritis

Abstract

Until recently the possibility of healing of erosive changes in RA has been neglected. When evaluating the radiographic course within clinical studies, a reduction of the radiographic score indicating improvement was not allowed since repair of erosions was considered to be impossible. During the last 3 decades several case reports and case series have been published demonstrating convincingly that healing of erosions of RA patients really occurs. In addition, a subcommittee on healing of the OMERACT imaging committee undertook to confirm the existence of repair by performing several studies: different experts had to evaluate erosions on radiographs of the same patients taken at two different time points demonstrating deterioration or improvement. Blinded to the sequence of the films they agreed which film was better or worse and which erosion was greater or smaller. Since 50% of the films showing improvement were taken at the second time point, that study confirmed that healing really exists. Owing to several special features healing could be diagnosed without knowing the sequence of the films in one study, not convincingly so in another study. Among different features indicating healing on radiographs the following can be distinguished with relative certainty: "re-cortication", meaning the re-appearance of a cortical plate that had been destroyed; "filling-in", meaning filling of an erosion with new bone; "restoration", meaning complete normalisation of the shape of the joint and the trabecular structure of the subchondral bone. The best agreement between observers concerns erosion size. Radiographic evaluation blinded to the sequence of the films in trials with biologics resulted in negative scores exceeding the measurement error of the scoring method in a certain percentage of patients, again supporting the existence of healing. As healing only occurs in an individual joint after the inflammatory process has been quiet in that joint for several months, healing could be utilized as an outcome measure in addition to the slowing or arrest of progression. This article gives an overview over the history and present knowledge of radiographic signs of erosion healing.