Objective: To assess the information available from routine bone scans on prevalence and joint distribution of osteoarthritis (OA), particularly of the hand.
Methods: Consecutive whole body bone scans of 414 patients, including a special hand projection, were analyzed for evidence of OA related uptake. After exclusions for various reasons, 297 scans were considered "representative" with regard to hand OA (108 male and 189 female patients). Kappa values for interreader agreement ranged from 0.61 to 0.82 for hand joints and was slightly lower for other joints.
Results: The prevalence of positive hand joints was low before the age of 40, but increased rapidly in the 5th and 6th decade to reach a plateau. Women had a higher prevalence of uptake than men in the carpometacarpal-1 (CMC1) joint and patella. Uptake was similar on the dominant and non-dominant sides in all joints with the exception of the shoulder. Subchondral knee uptake prevalence tended to decrease in the oldest age groups, but other joint sites showed a steadily increasing prevalence throughout life. Hand symptoms were related to distal interphalangeal (DIP) and CMC1 uptake, thumb symptoms with first metacarpophalangeal joint (MCP1) CMC1 uptake, and knee symptoms with the subchondral knee uptake pattern. Affected hand joint distribution was characterized by a strong bilateral concordance within rows, and an association was seen between subchondral knee uptake and hand involvement, particularly in the DIP joints, but to a lesser degree also with CMC1 and proximal interphalangeal (PIP) uptake. Association between spinal sites and between the forefoot and the knee was also observed.
Conclusion: Bone scintigraphy is valuable method in epidemiological studies of OA, with acceptable interreader reproducibility and relation to joint symptoms. Although much of the current findings seem comparable with previous radiologic studies, they provide new ideas about age related patterns and joint subsets, possibly indicating a difference in pathogenetic mechanisms among joints in OA.