BONE FORMERS - OSTEOPHYTE AND ENTHESOPHYTE FORMATION ARE POSITIVELY ASSOCIATED

Objective-To test the hypothesis that enthesophyte formation and osteo phyte growth are positively associated and to look for associations be tween bone formation at different sites on the skeleton so that a simp le measure of bone formation could be derived. Methods-Visual examinat ion of 337 adult skeletons. All common sites of either enthesophyte or osteophyte formation were inspected by a single observer who graded b one formation at these sites on a 0-3 scale. The total score for each feature was divided by the number of sites examined to derive an enthe sophyte and an osteophyte score. Cronbach's alpha and principal compon ents analysis were used to identify groupings. Results-Enthesophyte fo rmation was associated with gender (M>F) and age. There was a positive correlation between enthesophytes and osteophytes (r = 0.65, 95% conf idence interval, 0.58 to 0.71) which remained after correction for age and gender. Principal components analysis indicated four different gr oupings of enthesophyte formation. By choosing one site from each grou p a simple index of total skeletal bone formation could be derived. Co nclusions-Osteophytes and enthesophytes are associated, such that a pr oportion of the population can be classified as ''bone formers''. Enth esophyte groupings provide some clues to aetiopathogenesis. Bone forma tion should be investigated as a possible determinant of the heterogen eity of outcome and of treatment responses in common musculoskeletal d isorders.