[Early Diagnosis of Osteoarthritis: Clinical Reality and Promising Experimental Techniques]

It is considered that the structural damage in early osteoarthritis (OA) is potentially reversible. It is therefore particularly important for orthopaedic and trauma surgery to develop strategies and technologies for diagnosing early OA processes. This review presents 3 case reports to illustrate the current clinical diagnostic procedure for OA. Experimental techniques with translational character are discussed in the context of the detection of early degenerative processes relevant to OA. Non-invasive imaging methods such as quantitative MRI, ultrasound, optical coherence tomography (OCT), scintigraphy and diffraction-enhanced synchrotron imaging (DEI), as well as biochemical methods and proteomics, are considered. Early detection of OA is reviewed with minimally invasive techniques, such as arthroscopy, as well as the combination of arthroscopic techniques with indentation, spectrometry, and multiphoton microscopy. In addition, a brief summary of macroscopic and histologic scores is presented. Finally, the spatial organisation of joint surface chondrocytes as an image-based biomarker is used to illustrate an early OA detection strategy that focusses on early changes in tissue architecture potentially prior to damage. In summary, multiple translational techniques are able to detect early OA processes but we do not know whether they truly represent the initial events. Moreover, at this point it is difficult to judge the future clinical relevance of these procedures and to compare their efficacy, as there have been comparative studies. However, the expected gain in knowledge will hopefully help us top attain a more comprehensive understanding of early OA and to develop novel methods for its early diagnosis, therapy, and prevention. Overall, the clinical diagnosis of early OA remains one of the greatest challenges of our field. We still face uncharted territory.