The Archaeology of Joint Disease

Abstract

Not all diseases leave their mark on the bones. The major killers of the past, such as the infectious diseases of childhood, gastroenteritis, pneumonia and septicáemia from infected wounds, as well as cardiovascular and neurological conditions, in general leave no trace. Joint disease, however, does leave its mark on the bones, and along with trauma and dental disease the arthritides comprise most of the evidence for disease in ancient humans as revealed in their skeletal remains.

Diagnosis of joint disease presents problems to the palaeopathologist in that one cannot extract a family or personal history or elicit signs and symptoms from a bony skeleton, and neither can one undertake the barrage of laboratory examinations available to the modern physician.

The distribution of joint disease (as well as its appearance) is of vital importance in arriving at a diagnosis, and this underlines the necessity of careful excavation and recovery of as much of the skeleton as possible.

The pattern of distribution of degenerative joint disease can give an indication as to the occupation of an individual or community, and the study of ancient skeletons contributes not only to our knowledge of the history of medicine and disease, but also contributes to the understanding and practice of modern clinical medicine.

Funerary archaeology, amongst other things, entails digging up ancient human skeletal remains. A wealth of information can be obtained from a study of these ancient bones. Palaeopathology, or the study of ancient disease, is just one of a long list of studies that can be undertaken on ancient bones. What I shall be doing here is to give a brief account of joint disease, which is just one of a whole gamut of disease processes available to the palaeopathologist for study.

There are some fundamental differences between the study of diseases on ancient skeletons and the study of disease in modern living populations. One of the obvious differences is that one cannot extract a family or personal history from a bony skeleton. Neither can one elicit signs nor inquire about symptoms from a bony skeleton, and neither can one undertake the barrage of blood and other laboratory examinations available to the modern physician which aid in diagnosis.

Another obvious difference is that without any soft tissue remains, only those diseases which leave their mark on the bones can be detected. And as not all diseases leave their mark on the bones, then the range of disease which can be diagnosed by the palaeopathologist is restricted compared with that available to the modern physician. Most of the major killers of the past, such as the infectious diseases of childhood, gastroenteritis, pneumonia, septicaemia from infected wounds as well as cardiovascular and neurological conditions, in general leave no trace on the bone.

Joint disease, however, does leave its mark on the bones, and along with dental disease and trauma, the arthritides comprise most of the evidence for disease in ancient humans as revealed in their skeletal remains.

Of course, before diagnosing pathology on bones, one has to be familiar with the normal appearance and variants of the bones, and one has also to exclude any pseudopathology such as postmortem erosions caused by the tooth puncture marks of scavenging carnivores.

The diagnosis of joint disease from ancient skeletons is based on the evaluation of two fundamental parameters:

• 1. The morphology or gross appearance of the articular lesions;

• 2. The distribution of the lesions in the skeleton.

The most commonly occurring joint disease seen in archaeological human groups is osteoarthritis, just as it is the most common joint disease of modern populations. Osteoarthritis is as old as the hills; it has even been diagnosed in the fossilised spine of a 100 million years old Comanchean dinosaur! The archaeological diagnosis of osteoarthritis depends on the demonstration of three morphological features. Firstly, there is the demonstration of porosity on a joint surface, which occurs as a result of bone degeneration on the joint surface following destruction of the cartilage. Another feature characteristic of osteoarthritis is the formation of osteophytes on the joint surface or margins of the joint. And the third diagnostic feature of osteoarthritis is the presence of sclerosis or eburnation of the joint surface. This is seen as a hard shiny surface on the bone, which is often grooved where bone has been rubbing on bone.

Apart from the morphological appearance of the lesions, the other fundamental parameter used in the diagnosis of joint disease in ancient skeletons is the distribution of the lesions. We all know, for example, that osteoarthritis, rheumatoid arthritis, gout, psoriasis and ankylosing spondylitis tend to have a specific distribution in the joints of the body. And this underlines the importance of the careful excavation and recovery of as much of the skeleton as possible, so that the distribution of the lesions in the skeleton can be mapped out, as this aids in the differential diagnosis.

Unfortunately, in practice, we are rarely presented with a complete and perfect skeleton. All too often, the reality is that we are dealing with fragmented and incomplete remains. And this particularly applies to the small bones of the hands and feet, which are crucial in the diagnosis of joint diseases. All too often, these small bones do not survive the burial conditions, or they are so fragile that they are lost in the excavation procedure. Another reason for the loss of these small bones can be due to the burial customs of the ancient people themselves, such as the amputation of fingers from the corpse for separate burial beneath the floor of the house.

A local example of the postmortem interference with the bones of the hands and feet comes from the late Punic/early Roman tomb discovered in the middle of Tal-Barrani Road in 1993 during the course of excavation of a trench for the laying of an electricity cable. A pair of burials was discovered at the base of the trench, neither of the skeletons exhibiting any hands or feet. Examination of the contents of a ceramic jug positioned at the foot of these skeletons revealed it to contain an assortment of carpal and tarsal bones, as well as metacarpals, metatarsals and associated phalanges. For good measure it also contained three coccygeal bones as well as a wooden shroud or hairpin. But there were not enough bones to account for two full sets of hands and feet.

This pair of burials must have represented the first inhumations in the tomb, and they must have been completely decomposed by the time subsequent burials took place. In fact, there were four other burials in this tomb. The mourners or relatives at the subsequent burials must have carefully collected the hand and foot bones and the coccygeal bones and placed them in the juglet. What happened to the missing bones is not known, but this is an example of postmortem interference with the skeleton resulting in partial loss of hand and foot bones, which can complicate the diagnosis of joint disease in archaeological specimens.

Thus far, I have alluded to some of the problems associated with the archaeological diagnosis of joint disease. However, there is one important advantage that the archaeologist has over the modern physician. And that is that he is able to examine the joint surface directly with the naked eye without any intervening soft tissue getting in the way. He can twist and turn the bone and look into every nook and cranny of the joint surface. The benefit of this can be seen in the results of the work done by Rogers, Watt and Dieppe (1990). They examined 24 knee joints from 14 skeletons, the joints ranging from normal to those with severe osteoarthritis. The joints were assessed visually by a palaeopathologist and radiologically by a radiologist, who was unaware of the visual findings. The visual and radiographic assessments were then compared. 8 out of the 24 joints were normal by both techniques. Various changes of osteoarthritis were noted on visual assessment in the remaining 16 joints, but radiography picked up abnormalities in only 2 of these joints. Severe osteophytosis and eburnation were often not visible on the radiographs even when examined with hindsight. The regions where large osteophytes and areas of eburnation were missed on the radiograph were principally on the patellar groove of the femur and on the antero-posterior aspects of the tibio-femoral joint.

There seem to be two clinical implications resulting from this study. Firstly, it can explain the discrepancy between radiographic findings and clinical symptoms complained of by the patient. Areas of osteophytosis and eburnation may cause symptoms or functional problems but may remain invisible to clinicians and to radiologists. Secondly, these findings can also be of some practical use. They demonstrate where the blind spots to these osteoarthritic changes are on the radiographs, and they can suggest what additional or specialised views may be taken to make them visible radiologically.

As clinicians, your interest in making a diagnosis of joint disease is to account for the patient’s symptoms and thereby plan the necessary treatment for the relief of these symptoms. The agenda of the archaeologist, however, is somewhat different. The archaeologist is an historian, so his primary aim is to extract as much information as possible from the artefacts that he digs up, and with this information he tries to reconstruct the lifestyle of the individuals and communities he excavates. Although he sees the state of health of an individual at one particular moment in time, that is, at the time of death, the archaeologist tries to reconstruct what effect these lesions would have had on the individual during his or her life. The archaeologist is more interested in what the information he extracts from a skeleton can tell us about the living than about what it tells us of the state of health at the time of death.

In this regard, one of the particular areas of interest to the archaeologist is the correlation between the type of occupation of an individual and the development, subsequently, of osteoarthritic joint disease at particular sites. The archaeologist is interested in trying to see if the joint disease he identifies on a skeleton can tell us about the occupation or lifestyle of the individual.

There are plenty of examples from modern clinical practice that people practising particular occupations tend to develop osteoarthritis and other skeletal changes at particular sites. The well known “squatting facets” on the tibia and talus associated with prolonged periods of squatting, tennis elbow, golfer’s big toe, seamstress’s fingers and the degeneration of the elbow and shoulder joints from the use of pneumatic drills are some such examples. They are known as “skeletal markers of occupational stress”, and they have been recognised since Elizabethan times. The chronic inflammatory condition of ischial bursitis, which can produce bilateral osteitic ischial tuberosities, such as occurs in weavers who sat for long periods of time at their looms, and is known as “weavers’ bottom” seems to have been known to Shakespeare who selected the name Bottom for his weaver in “A Midsummer Night’s Dream”.

The archaeological literature abounds with studies based on the relationship between osteoarthritis and occupation. One interesting example of a skeletal marker of occupational stress, although not actually osteoarthritis, comes from Henry VIII’s flagship, the “Mary Rose”, which sank off the south coast of England in 1545. Of the 110 skeletons recovered from the wreck, 15 individuals (13.6%) had os acromiale, or non-fusion of the acromion process. This compares with 8% found in modern dissection room studies. The highest frequency of os acromiale in the “Mary Rose” group came from the area of the ship where archery equipment was stored. As longbows were used from a very early age at this time, well before the fusion of the acromion could have occurred, it is thought that the stresses on the rotator cuff involved in archery practice, contribute to the development of os acromiale. (Stirland, 1986).

Much valid work has been done in the field of skeletal markers of occupational stress. However, the quest to deduce as much as possible about the lives of individuals from their skeletons does sometimes seem to have led to extravagant claims having been made about occupationally related activities, and some caution is called for in interpreting these results, but it is a fascinating line of investigation.

In contrast with osteoarthritis, rheumatoid arthritis is only rarely seen in the archaeological record. There could be several reasons for this, and one of these seems to be that rheumatoid arthritis may be a relatively new disease. And this is another factor that should be kept in mind when studying disease on ancient skeletons. Some diseases that existed in the past could have died out, and conversely some diseases that we are familiar with today may not have existed in ancient times. Rheumatoid arthritis seems to be one of these diseases, and its presence in the archaeological record before the medieval period seems to be open to question. A recent report claims to describe the “first evidence of rheumatoid arthritis in the United Kingdom” in a skeleton from the post-medieval period (Waldron and Rogers, 1994). So archaeology can tell us a lot about the history and development of joint disease.

Conditions that must be considered in the differential diagnosis of osteoarthritis and rheumatoid arthritis are gout and psoriasis. The literature of gout goes back to the Hippo- cratic school, and the most celebrated example of gout in the archaeological record comes from an Egyptian mummy of the Christian period in which actual deposits of urate crystals were identified in the gouty joint.

As for psoriasis, few specific examples have appeared in the palaeopathological literature. Perhaps it is being underdiagnosed. I have already referred to one of the problems that may account for underdiagnosis, namely the lack of survival of enough of the small bones of the hands and feet. In other words, the evidence is simply lost. Another problem could be that as the more severe and chronic bone changes do not occur until later in life, and as people in ancient times generally did not live as long as we do today, then perhaps there just was not enough time in many cases for demonstrable lesions to occur in the first place. But, whatever the cause, the incidence of erosive arthropathies seems to have been much less in ancient times.

Ankylosing spondylitis and Forestier’s disease, or diffuse idiopathic skeletal hyperostosis, are also recognised in the archaeological record. Although first described as a disease by Forestier and Rotes-Querol as recently as 1950, the disease has been described in a skeleton of Neanderthal man from Iraq, dated to between 40,000 and 70,000 years ago. It is interesting to note the lack of development of osteophytes in the left lower thoracic spine in this condition. They are probably inhibited from developing in this region because of the pulsations of the lower thoracic aorta. This is well demonstrated in one of the Tal-Barrani skeletons.

Localised septic arthritis is also represented in the archaeological record, as is involvement of the joints in the systemic infections of leprosy, syphilis and tuberculosis. Perthes disease and trauma/dislocation are also encountered. But because of the limitations associated with palaeopathological diagnosis, only a fraction of the myriad of joint diseases known to modern medicine can be diagnosed with confidence from the bones of our ancestors.