When hard work is disease: the interpretation of enthesopathies Charlotte Henderson Department of Archaeology, Durham University, Science Site, South Road, Durham, DH1 3LE e-mail address for correspondence: c.y.henderson@durham.ac.uk Abstract Enthesopathies, lytic lesions or bone spurs at sites of tendon, ligament or joint capsule attachments to bone, can be seen in radiographs, in cadaver samples and human skeletal remains. Many factors can contribute to their formation. However, it is the relationship between appendicular enthesopathies and physical exertion (or repetitive labour) that has captured the imagination of bioarchaeologists. In this context they are called musculoskeletal stress markers (MSM). Whilst there are clinical papers which discuss stress induced enthesopathy formation, they generally focus on disease processes (particularly the seronegative spondyloarthropathies) associated with enthesopathies. There are bioarchaeological papers discussing disease related enthesopathy formation, but compared to that on MSM, the research is negligible. This study explores the relationship between enthesopathies in the upper limb and bone-forming diseases. Clinical literature was reviewed and a list of diseases known to cause enthesopathy formation in the appendicular skeleton compiled. General diagnostic criteria for these diseases were created and used to divide skeletons from the late medieval site of Fishergate House, York into two groups: 1) disease free; 2) possible enthesopathy forming disease. Chi-square tests (p<0.05) were used to compare the frequencies of upper limb enthesopathies in groups 1 and 2. It was hypothesised that the skeletons with “diseases” would have a higher frequency of enthesopathies. This was confirmed and statistically significant (α=0.05). This demonstrates that for the study of MSM, skeletons with possible enthesopathy forming diseases must be excluded to avoid over-estimation of physical activity levels. Keywords: musculoskeletal stress markers (MSM), enthesopathies, seronegative spondyloarthropathy, diffuse idiopathic skeletal hyperostosis (DISH), bone formers Introduction One of the subfields of bioarchaeology is the study of activities undertaken by our ancestors (e.g. Hawkey and Merbs, 1995, Kennedy, 1998, Capasso et al., 1999, Jurmain, 1999). The majority of this research focuses on MSM in the upper limb bones (Hawkey, 1988, Jurmain, 1999, Molleson, 1989), because this is thought to be more “activity-specific” than changes in the lower limb which may be caused by walking. The study of activity patterns is an important field: if skeletons can be used to explore labour patterns, then the lives of individuals and groups of individuals can be studied and compared temporally, geographically and socio-economically. Key stages in human history, such as the transition from hunting and gathering to agriculture may be elucidated, as may questions concerning social status and biological sex in relationship to workload. There has been considerable research in this field, as demonstrated by the dedication of a volume of the International Journal of Osteoarchaeology (Kennedy, 1998). A common method used is to study the presence of, what are commonly called, musculoskeletal stress markers (MSM) in skeletal remains. MSMs can be described as bone formation and/or destruction at sites of tendon, ligament, or joint capsule attachments to bone (the clinical term for the attachment is enthesis). These abnormalities take the form of lytic lesions, bone spurs (Figs. 1-2) and the presence of woven bone at the attachment site. MSM, however, is a loaded term; it implies the direct link between musculoskeletal stress and these abnormalities. Clinically, the term enthesopathy is used, as this lacks implied aetiology. The term enthesopathy will be used throughout this paper, except where reviewing bioarchaeological research. Figure 1. Example of proliferative enthesopathy (bone spur) at the lateral epicondyle (common extensor origin) of the humerus.