Scintigraphic changes of osteoarthritis: An analysis of findings during routine bone scans to evaluate the incidence in an Indian population

AIMS: The reported prevalence of osteoarthritis (OA) varies according to the method that is used to detect it. X-rays are commonly used in the diagnosis of OA. However, marked osteoarthritic damage must be present to detect characteristic changes with radiologic imaging. Our intention was to evaluate bone scans (1) he occurrence of such changes, (2) he incidence of OA (single or multiple joints) in the general population (a mixture of urban and rural) who were asymptomatic. Data on OA incidence in India is sketchy and sparse as against more detailed information obtained from USA and European nations. Also, clinical rheumatologists are not well-versed with the potential application of bone scans in the management of arthritides. MATERIALS AND METHODS: Two hundred and eighty nine planar images of routine bone scans were randomly evaluated by two trained nuclear medicine physicians. The ages of the patients ranged from 20 to over 80 years. RESULTS: It is observed that as the age increases, the incidence of joint involvement increases. However, it is worth noting that even in the age group of 20-40 years, as many as 34% of asymptomatic persons have involvement of the joints. In this age group, as the manifestation is probably in the inception stage, there is a tendency for single joint involvement as against multiple joints seen in the older age groups. Another point to note is that the incidence of joint involvement was not affected by weight. In our patient population, gross obesity was not seen. The predominant joints involved are the knees and hips, followed by the shoulders and ankles. Females show a higher incidence than males. Some patients would be having only a single site or multiple site involvement. This observation is important as in a single, simple test whole body survey gives more information with low radiation burden. CONCLUSION: Scintigraphic prevalence of OA is higher than reported in US, Europe, and Asia as this test is more sensitive in detecting early changes as compared to radiological changes. These findings on scintigraphy in asymptomatic cases have not been described to the best of our knowledge. Epidemiological demography in published reports is based on clinical or radiological changes observed in single joints which are predominantly symptomatic and multiple joint involvement is rarely recorded. The sensitivity of scintigraphy to show early changes in bone homeostasis and remodeling needs to be exploited.