Arthroscopic assessment of articular cartilage in an animal model of osteoarthritis

Advances in our understanding of osteoarthritis (OA) have made development of sensitive measurement tools a priority. The literature review in this thesis found that one of the measurement tools, arthroscopy, had not been fully evaluated. This body of work evaluated the performance of arthroscopic assessments of articular cartilage (AC) in early OA with specificreference to the OMERACT filter. Preliminary studies in plastic knee arthroscopy simulation models found that estimates of AC lesion area had poor accuracy and reliability. Measurements of lesion diameter were greatlyimproved by the use of specially designed measurement probes but these did not prove feasible in vivo. Ovine studies evaluated discriminant and criterion validity. Biomechanical assessments served as the gold standard for AC stiffness while macroscopic, thickness and histologic assessmentswere used for gross structural damage. An hybrid gold standard assessment was devised to validate arthroscopic estimates of Severity and Extent of chondropathy. Arthroscopic global assessments discriminated between normal and very early OA but discrimination between different states of OA was less impressive. Assessments of the Severity of chondropathy hadacceptable accuracy and moderate reliability. While arthroscopy could not examine the entire articular surface and estimates of Extent of chondropathy were subject to very large error they broadly resembled those of the hybrid gold standard assessment and they enhanced composite score performance. Composite score validity was further improved by inclusion of estimates of chondro-osteophyte. An empirical approach to composite algorithm weighting to optimise discriminant validity was developed. This approach compared favourably with previously described methods. Composite scores proved best at discriminating between normal and veryearly OA but were also capable of detecting small changes in OA.Arthroscopic asessments of AC damage meet the OMERACT filter criteria of Truth and Discrimination. Assessments using current arthroscopic technology should include estimates of the Extent of all grades of chondropathy. The optimal scoring algorithm should be determinedempirically. Arthroscopic assessments using existing technology may be used to validate noninvasive assessments of the Severity chondropathy but not of Extent. Future efforts to improve arthroscopic assessments of AC should focus on reducing random error associated with estimates of extent