[abstract] HYDROXYPROLINE AS AN INDICATOR OF BONE NECROSIS IN RABBITS.

Abstract

Aseptic necrosis of bone is an important chronic complication of deep diving. As the radiological changes seen in this condition do not appear before 3 months there may be long delays in its diagnosis. The management of this condition Might be significantly improved if there was less delay in the detection of the bone damage. Using glass microspheres injected at operation into the external iliac artery of rabbits Cox (Forsvarsmedicin, 9, 520-524, 1973) was able to produce aseptic necrosis of bone in the ipsTlateral femurs. Although histological lesions were apparent by 4 days radiological changes were not seen in less than 3 weeks. We have been able to show that the 24 hour excretion of hydroxyproline is a sensitive and early indicator of bone damage produced in this way. The daily urinary hydroxyproline excretion from 11 rabbits injected with a saline suspension of glass microspheres was contrasted with that from 7 control rabbits injected with saline only. Hydroxyproline estimations.were made for 1 week pre-operatively and for 20 days post-operatively. An increased excretion of hydroxyproline was observed in all rabbits developing histological evidence of bone necrosis. This increase, which was statistically significant (p<O.Ol), was detectable by the end of the 5th post-operative day and persisted for 20 days. No X-ray changes developed in the period of study. It is suggested that estimations of urinary hydroxyproline levels may be useful in the early detection of bone necrosis in man. (Research supported by M.R.C. grant.)