Abstract 11

BONE MARKERS IN OSTEOARTHRITIS

Mellick Chehade, *Susan Neale, Nick Fazzalari¹, Helen Tsangari¹, Susan Pannach, Shelley Hay, Peter O'Loughlin², David Findlay

Departments of Orthopaedics and Trauma, Royal Adelaide Hospital and University of Adelaide, ¹Department of Tissue Pathology, IMVS, and ²

Osteoarthritis (OA) is characterised by progressive degenerative damage to the articular joint cartilage. Evidence is accumulating that bone changes in primary OA may be important in the disease etiology, and that changes in subchondral bone may actually precede cartilage changes. The aim of our study was to measure biochemical markers of bone turnover, and to relate the results to other clinical parameters, in patients with severe OA of the hip.

Blood and urine were collected from patients presenting for hip replacement surgery, both at pre-admission clinic and on the day of surgery, 3-4 weeks later. The markers measured were serum creatinine, osteocalcin, alkaline phosphatase, and urinary pyridinoline and deoxypyridinoline. Serum OPG and RANKL, important molecules in regulating bone turnover, were measured using a commercial sandwich ELISA assay. Patient details recorded included whether their OA was localized or general, co-morbidities, BMI, age and gender.

Analysis of 55 patients found that levels of these biochemical markers were closely similar at the two sampling times, with the exception of osteocalcin, which varied between fasting and non-fasting states. Importantly, 21%, 32% and 40% of the measured values for alkaline phosphatase, urinary pyridinoline and deoxypyridinoline respectively were greater than the normal value range for these markers, suggesting that OA may be a disease of increased bone turnover rate.

This information will be of great assistance in further elucidating the mechanisms that lead to bone changes in OA and other diseases of the skeleton. We are also hopeful that a particular profile of bone markers may be diagnostic of OA and may even be useful as an early indication of the development of this disease.

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