Unlike osteoarthritis, one of the two traditional categories of arthritis, rheumatoid arthritis falls under the category of erosive arthropathies (Ortner, 2003). As a general rule, rheumatoid arthritis tends to affect the appendicular skeleton, and unlike osteoarthritis there is usually minimal reactive bone formation. It is the most common of erosive arthropathies in modern populations, affecting around 1% of the total population (Firestein, 2009). The cause of this particular erosive arthropathy is unknown, but there is a broadly accepted hypothesis that it is the result of an environmental stimulus acting on a genetic predisposition (Koopman, 2005). It can be inferred, then, that as the rheumatoid arthritis is more common in females than males at a 2:1 ratio, females are more likely to have this genetic predisposition. With respect to the anatomy affected, the joints of the hands are first and most frequently involved, and the most frequently affected large joint is the knee. The joints of the axial skeleton are very unlikely involved with this condition (Resnick, 2002).
The disease process of rheumatoid arthritis is one of an “inflammatory infiltration and proliferation of the synovium” which becomes highly vascularized, extending further into the joint, and gradually destroys the cartilage which with it contacts (Koopman, 2005). Usually this process, like osteoarthritis, progresses over many years and in some severe cases destroys all of the joint cartilage. In untreated cases, as are to be seen in the medieval archaeological record, there is possible loosening of the joint and subluxation (incomplete or partial dislocation of a joint). In some cases mobility is maintained in the joint; in such cases degenerative arthritis, such as osteoporosis, which will be discussed subsequently, may superimpose itself.
With respect to the archaeological record, evidence of rheumatoid arthritis was first reported from a Neolithic site on the isle of Gotland in Sweden, between 2500 and 1500 BCE (Leden et al., 1988). Although this is clearly outside of the medieval time range, it demonstrates the ability of the paleopathologist to diagnose rheumatoid arthritis in the archaeological record. It must be stressed, however, that any specific diagnosis of an erosive arthropathy must be met with caution, as there is an overlap in diagnostic criteria that occurs in clinical cases (Ortner, 2003). As a direct reflection of this, with respect to the medieval period, there is much debate over whether rheumatoid arthritis did or did not in fact exist in Europe at the time, some speculating that it had its origins in the New World, that in fact the Neolithic evidence in Sweden is not rheumatoid arthritis (Woods & Rothschild, 1988; Rothschild, 1992; Rothschild et al., 1992). Noting that the clinical criteria for rheumatoid arthritis is not applicable to paleopathological material, Blondiaux et al. (1997), however, establish through dismissal of other arthropathies which can be diagnosed, the existence of rheumatoid arthritis before the fourteenth century in Europe (Hacking et al., 1994).
Osteoporosis (Figure 3), the final bone disease of interest, is a loss of bone mass (osteopenia), resulting in bone fragility and increased susceptibility to fracture, that is a result of the hormonal changes associated with aging, particularly in women, and is a metabolic disorder considered a growing health concern in the aging populations of developed countries today, as it is increasing and at its rate is not explained by increasing life expectancy (Melton & Whaner, 1989; Kanis, 1990; Ross, 1996; Poulsen et al., 2001; Ortner, 2003; Agarwal et al., 2004). Because few individuals in the medieval period lived long enough to feel the effects of osteoporosis, it is not as prevalent as osteoarthritis. Nonetheless, it does happen and is documented in a medieval context. As such, it is important for the paleopathologist and medieval archaeologist alike to be familiar with its manifestations and causes.
Figure 3: This image from the NIH demonstrates the disparate density of trabecular bone in the femoral head between a 'normal' and pathological, osteoporotic individual.
Osteoporosis resulting from the aging process, or senile osteoporosis, is a condition in which the bone mineral density of an individual is significantly diminished as a result of an imbalance between bone formation and bone resorption, specifically formation lagging behind resorption (Riggs & Melton, 1988; Kanis, 1994; Manolagas & Jilka, 1995). Primary osteoporosis comes in both a postmenopausal (type I) and age-related (type II) form (Agarwal et al., 2004). As a general rule, it does not manifest itself before the age of 50, with exception, and is more prevalent in females than in males (Ortner, 2003). The reason for this is the decrease in estrogen levels of females at menopause compared with the gradual decrease of testosterone in males, although at a very elderly age (i.e. 80) similar rates are observed in both males and females, and extrinsic factors such as the sedentary habits and cigarette smoking of modern Western lifestyles also seems to play a part (Peck, 1983; Resnick, 2002; Sevenson et al., 1989; Mays, 1996; Agarwal et al., 2004). Such ages and habits, however, are not generally reached or seen, respectively, in the medieval period. As such, the medieval archaeologist is much more likely to see osteoporosis in females, and if otherwise there is cause for further investigation.
Anatomically, osteoporosis does not affect the entire skeleton similarly. As it has its greatest effect on trabecular bone, bones such as the ribs, pelvis and spine are most severely affected. In general these bones become weaker and therefore are much more susceptible to fracture. The most diagnostic bone with respect to the effects of osteoporosis, however, is the femur on its neck and head portion. The trabecular bone of the femoral neck and head is designed in direct response to the biomechanical stresses placed upon it, and as such osteoporosis of this portion of the femur may result in characteristic fractures of the femoral neck. As this is the primary site of force transmission from the head, arms and trunk (HAT) to the lower extremities, a fracture here is likely to be completely debilitating to the average medieval individual. These fractures, it will be demonstrated, have varying prevalence across geographic local in medieval Europe that is not seen in modern populations.
As a process, osteoporosis manifests itself in the skeleton in two ways: (1) reduction in the number and diameter of trabeculae with simultaneous thinning of cortical bone, and (2) a change in osteon remodeling of the bone, in which the bone resorption process (osteoclastic action) is diminished and a larger, more open central canal is left (Ortner, 2003). As such, with respect to archaeological accounting for this bone disease, one must go deeper than the surface, which may not reflect the change in trabecular bone architecture and osteon, or Haversion, canal size. To account for this many archaeologists take cross-sections of long bones to look for evidence of osteoporosis, often times analyzing both the cortical and trabecular bone as well as the diameter of the medullary cavity in the diaphysis (Dewey et al., 1969; Ericksen, 1976). Such lengths must be taken by the paleopathologist or medieval archaeologist to determine the actual significance of bone disease in the population studied. With adequate data collection in this regard, questions of social care and quality of life for both post-menopausal females and the elderly may be better understood.
As the various aspects of the bone pathologies have been described, it is now necessary to outline their presence with respect to sex, age, and geographic location in the medieval period in particular. Because each of these variables, in practically every case, affect each other, the data have been categorized to that variable with which its value can be best recognized. For instance, although age has an effect on progression of bone mineral density loss, if the comparison is that of women versus men throughout the aging process, the data will be discussed with respect to sex and not age. With this being said, some of the cases warrant repeating and as such are included in more than one section.
With respect to sexual variation in the prevalence of bone pathology in the medieval time period, the most striking contrast to the present day is that observed by Waldron (1992). In this analysis of skeletons recovered from a Black Death plague pit on the side of the old Royal Mint opposite the tower of London, the data show a prevalence of osteoarthritis that was higher in males than in females, although approximately two-thirds of the males and the females had osteoarthritis at a single site. In modern studies of the epidemiology of osteoarthritis, however, the data demonstrate that it occurs at a 2:1 ratio, female to male (Kirwan & Silman, 1987). This may suggest that the higher female to male ratio may be a recent phenomenon, which is further supported by Waldron (1997). With respect to a medieval comparison, however, Waldron (1992) lies in direct contrast to Poulsen et al. (2001) in which it was demonstrated, with a population of medieval Danish skeletons, that BMD was higher in men, attributable to a higher level of physical activity, although age-related bone loss was virtually identical to that of contemporary men (Smith & Gilligan, 1996; Poulsen et al., 2001). The former, of course, may be a result of geographical variation, a topic that will be discussed with respect to these cases in particular later.
