1. Summary
In spite of a large body of literature on the vertebral column, there are very few detailed studies attempting to deal with all aspects of the human spine in a coherent way. The reason for this may be the very complexity of the spinal column. Structurally and functionally the spine is of extreme importance and it is desirable to attempt such a study, especially on a North American population, for there are no detailed analyses of native American vertebrae available in the literature.
Ossuary burials provide the osteologist with large samples. Ossuary material is representative of a limited population over a time period which can be estimated, from historical accounts of the Huron Indians, to be between 8 and 15 years. For these reasons, the skeletal remains excavated from ossuaries are excellent objects of study for the osteologist. Nevertheless, there are inherent problems arising from the disarticulated nature of ossuary material. A study of ossuary vertebrae entails an enquiry into the best methods of dealing with disarticulated spinal columns.
This thesis has presented evidence on the vertebrae contained in the Kleinburg Ossuary. Kleinburg is a large ossuary comprising 500 to 600 individuals. The group from which these individuals were drawn can most economically be regarded as Huron of the period just prior to movement north into Huronia and contact with the French.
A great number of vertebrae and vertebral fragments was contained in the ossuary. The majority have been examined in some detail, although juvenile and infant vertebrae were not in general studied.
Large series of measurements were made on many vertebrae and I have provided diagrams illustrating methods of measurement, and a discussion of techniques. Metrical data is of importance in analysis of fossil specimens and in studies of developmental and age changes. Here, I have considered especially the value of metrical data in sexing vertebrae, concentrating on the atlas. The conclusion is that, for general purposes, it is not worthwhile to attempt to sex vertebrae but I have shown that some measurements will discriminate between male and female atlas, axis and L.5. A study using sexable North American native vertebrae may be of use, in that it would establish the discriminating measurements and it would allow sexing for special studies, for example, on the relationship of sex and variant morphology or degeneration.
I have made use of metrical data in a specialized way. The disarticulation characteristic of ossuary burial dictates that much time must be spent on sorting vertebrae. Since I wished to do close analyses of morphological variants and degeneration, it was necessary to be as exact as possible in identifying the vertebrae contained in the ossuary. Chapter III presents a long discussion on the identification of vertebrae. The initial discriminatory characteristics are described and the method of dealing with variations is demonstrated. For example, the morphology of cervical vertebrae is known to vary amongst populations, not absolutely, but with regard to the relative frequency of foramen and neural spine forms amongst the middle three bones of the cervical spine, C.3 - C.5. Furthermore, the frequency of degenerative change is known to peak at C.4, C.5 or C.6 variably in different populations. It is thus desirable to gain some idea of the differences between C.3-4 and C.5 and between C.5 and C.6, although the usual practice would be to lump C.3 - C.6.
I sorted out C.6 on the basis of stated characteristics, noting those bones which did not accord with the expected total morphological pattern. I also noted bones which were possibly C.5. The frequency distributions of the morphological characters could then be compared. But a more stringent test was required and this was provided by comparing the means of the measurements (the raw data and t statistics are given in Appendix I). The metrical data indicated that the possible C.5 were different from the general C.3-5 category and thus probably represented C.5 vertebrae. The C.6 vertebrae which varied from the norm were shown to be somewhat different from C.6 in form but not from the C.5? category.
The method does not provide absolute certain identification, but it has 1) given a definite indication of bases of discrimination, e.g. spinous process length, which would not have been recognized otherwise; 2) indicated that C.5? is a valid category and that the frequencies of its characteristics may be (cautiously) discussed; 3) shown that a category, C.6, which would otherwise have been regarded as a well-founded grouping, should be viewed with a certain amount of distrust; and 4) options have been opened up, allowing one to draw upon data that would otherwise have been lost.
Broadening the range of options is of immense importance and this is shown in the discussion of the lower thoracic region (T.8-T.12) of the Kleinburg spine. The data presented on this region is of some significance, in that it has led not only to a description of morphological variation but to a demonstration of the contribution of morphology to the distribution of degenerative changes in the spine. This basic data would have been completely overlooked had not the sorting of the vertebrae been done in such a way as to provide opportunities for extensive manipulation of the data.
Chapter IV deals with general morphology in more detail, the problems of morphological variation amongst vertebrae having been raised in the previous chapter. Chapter IV provides the descriptive data on the morphology of the Kleinburg spine necessary to any general account of the osteology of the Kleinburg population. The percentage frequencies of the more important morphological variants are given in Appendix II in a form which will allow use of the data in population comparisons.
I have also made comments on observations of discrete traits. Since I have had available to me a large sample covering a number of age categories, it has been possible to point to age-dependent traits. The large series of vertebrae has permitted me to observe unusual variants and to suggest which anomalies might most usefully be observed.
For the atlas, attention is paid especially to spurring and bridging, and on the basis of very detailed coding it is shown that normal methods of coding are unsatisfactory. I have suggested that separate coding of both sites of spurring for each form is desirable since unpaired spurs are as common as paired spurs.
Study of the Kleinburg cervical spine has revealed a number of interesting anomalies and variants which have rarely or never been previously described. Several of these, such as the C.6 neural arch tuberosity and the pretransverse foramen of C.7, might well provide interesting data if examined in other populations. Some minor variants were observed in the thoracic spine but I would urge that most attention be paid to those characteristics which contribute to the identification of the vertebrae. Some characteristics are not easily coded or measured, for example the disposition and form of the transverse processes and the angle of the spinous process. The latter observation is often made and I, too, attempted it on some samples but found that it does require special measuring devices. However, observation on the form and placement of the various costal facets can easily be made because the facets will be examined for osteoarthritis in any case. The same holds true for the disposition of the zygapophyses. It might indeed be possible to sort after coding on the basis of these observations, in conjunction with anterior and posterior heights of the centrum. But there is no doubt that an osteologist should try to sort out at least T.9 to T.12.
My method of coding has made possible identification of the fact that, in a quite high percentage of the Kleinburg population, the thoraco-lumbar transition occurs between L.1 and L.2, rather than between T.12 and L.1. This differentiation is based mainly upon the orientation of the zygapophyses but, in fact, the total configuration of the vertebrae is altered by the change of the level of transition. Such a radical alteration is to be expected since a change in the orientation of the articular facet entails an alteration of the movements allowed at the T.12/L.1 joint.
Chapter V constitutes an attempt to give an overall picture of the various degenerative changes which may be identified in the spine. These changes may be grouped as 1) Schmorl's nodes and rupturing of the epiphyseal ring; 2) osteophytosis of the centra and pitting of the body surfaces; 3) osteoarthritis of the small joints; 4) laminal spurring and 5) wedging and collapsing of osteoporotic vertebrae. My aim in this discussion was to examine the pattern of the frequency distributions of these degenerative changes along the spine with regard to overall frequencies, as well as to types and degrees of changes. I then sought to identify relationships among the changes. Rupturing of the epiphyseal ring is shown to bear a relationship to anterior-posterior noding, but not to transverse and central noding which have completely different distribution patterns. In fact, the three forms of noding appear to have separable causes. It is suggested that anterior-posterior nodes result from rotation, transverse nodes from flexion, extension and lateral bending, while central stellate noding perhaps results from simple compression associated with less vigorous bending movements. "Deepened nodes" are analysed separately in view of their association with osteoporosis.
Noding is not correlated with osteophytosis but osteophytosis is strongly associated with another form of breakdown of the body surfaces, pitting or porosis. However, no form of degeneration of the centra is clearly related to arthritis of the articular facets. There is no clear association between facet arthritis and laminal spurring, for in T.3-8 there is a very significant preponderance of right over left side arthritic involvement which is not parallelled by the laminal spurring of T.3-8.
Noding and laminal spurring are the earliest forms of degeneration to be seen in the vertebral column, both occurring in juveniles, whereas degenerative breakdown of the body margins and of the articular facets does not begin until after adult status is reached.
I sought to isolate factors leading to degenerative changes by examination of the patterns of frequency distributions along the spine. It was noted that for all forms of degeneration, the patterns of the frequency distributions were altered from the "normal" when the thoraco-lumbar transition occurs at the L.1/L.2 level. The difference between the two morphological types, that of normal and lowered levels of transition, is most marked for noding and posterior ruptures of the epiphyseal ring. The histograms of the frequency distributions of the three forms of nodes and of ruptures graphically illustrate that noding is at least partially related to morphology and thus to movement rather than to the static demands of the vertebral column. The figures also show that a lowered thoraco-lumbar junction is at considerable risk. On the other hand, deepened nodes, osteophytosis, porosity of the body surfaces and osteoarthritis of the small joints do not generally occur more frequently at an anomalous transitional joint. Rather, the pattern is disturbed by generally lower frequencies, except for right side osteoarthritis. Marked laminal spurring does occur more frequently on anomalous T.12 than would be expected from the normal percentage frequencies, but in general, the risk for those with lengthened thoracic spines lies in noding. Only in noding do the morphological differences lead to alterations in the patterns of superior-inferior dominance. It is possible that the overall patterns of degeneration would differ between normal and anomalous spines but there is no way of testing this on the Kleinburg material. It remains an interesting question to be investigated.
My conclusion is that while ossuary studies of vertebrae may provide a great deal of evidence of interest, they cannot answer complex questions on the nature of degenerative processes. Such a conclusion is to be expected. Complex questions on degeneration have as yet received no answers, regardless of the material from which data has been collected. It is surprising that so much evidence could be garnered from disarticulated material. The information presented on noding and ruptures is much more complete than any published to date and that on other forms of degeneration at least raises important questions. This by itself validates the method employed in the analysis of the vertebrae from the Kleinburg Ossuary.
2. Conclusions and general comments
This study has been a diffuse one for it has encompassed three levels of analysis. The connection among the levels is logical: an enquiry at one level has led by natural progression to an enquiry at another level.
I began my study of osteology by an analysis of material from a test pit into the Kleinburg Ossuary. I quickly discovered that, although I was content to record standard observations in standard ways on most bones, the vertebrae appeared to me more interesting and more complex than standard methods allowed for. I became aware that although osteological and palaeontological vertebral material is available, little detailed work has been done on it. The reasons for this seemed simple. The vertebral column is such a complex structure and functions in so complex a way that it is avoided in many osteological studies.
My first level of analysis has been restricted to a characterization of the Kleinburg vertebral column. This has led to an attempt to deal with the special problems presented by ossuary material. It has also led to an enquiry into the nature of the best methods of studying, and the value of studying, a number of metrical, morphological and degenerative features of vertebrae.
This study would have been less than honest had it not stressed the difficulties inherent in the analysis of disarticulated material. Nevertheless, it will have served its purpose if it casts doubts on the statement made in the prefatory quotation, that it is "useless to examine the lumbar vertebrae in any detail", and on the implication that it is worse than useless to examine other vertebrae at all.
I have suggested simple methods of studying vertebrae from ossuaries or from other sites in which a mixing of individuals has occurred or in which complete vertebral columns have not been preserved. Firstly, without much effort, an osteologist can sort out most vertebrae, lumping C.3-5, T.3-8 and mid-lumbar bones. Other vertebrae can be distinguished and problematic bones can also be set aside in separate categories which can be analysed separately and may lead to insights into the morphology of the vertebral column. Such a method has led me to suggest that the osteologist's attention to morphological detail should be focussed especially on the thoraco-lumbar transition, particularly when dealing with North American material. The osteologist who, while not shamefully ignoring the vertebrae, makes no attempt to sort beyond cervical, thoracic and lumbar groupings, is lax and is wasting good material.
With regard to measurement, I have shown that in general terms measurement has limited value even for sexing. On the other hand, I would be opposed to an analysis which included no measurement at all. The measurements I took have proved useful time and again, not only in checking identifications but in specifying the characteristics of certain bones. One need only compare the vertebral height index of normal and anomalous first lumbar vertebrae to see that there are important morphological and therefore functional differences involved. I would also suggest that although I have placed most emphasis on heights of the centra, there are other even more easily taken measurements, of the vertebral foramen, for example, which could be of value in studying changes during development, adult age changes, sex differences and population differences. I would like to have available to me many more series of measurements, even of features which cannot be measured with perfect consistency, such as central width, in order to have some basis for comparison with other populations, extant and fossil.
In this thesis my attention has been focussed on forms of degeneration and the best methods of studying them. Degeneration of the vertebral column presents fascinating problems which are as yet without solution. The very complexity of the matter means that only through many populations being well and usefully observed can answers to the problems be gained. Final answers cannot come from experiments on the living, from X-rays or from placing small segments of autopsied vertebral columns in machines that twist or crush them. Of course, clinical and research work on living and dead subjects is important. The vertebral column is statically and dynamically affected by muscles and ligaments, by intra-discal pressures and by intra-abdominal pressures, but only the osteologist can observe the resulting pattern of bone changes. These changes are not just a matter of dry academic research, suitable for dry academic exercises. We are dealing here with questions of great and continuing importance. The moment man became upright he placed very special strains on his vertebral column. Every human population in the past, every population in the present and, no doubt, every population in the future will have in it a large number of individuals who at some time in their lives have suffered or will suffer from slipped discs, low back pain, and so on. There can scarcely be a person who has died without at some time in his life having had his whole consciousness centred on his aching back. To what extent is this the result of vertebral morphology and thus predictable and, possibly, avoidable? It is the osteologist studying the bony remains of those aching backs, able to examine large numbers of bones of peoples from all times and places of different ethnic and cultural groups, of different genotypes and phenotypes, who moved through a variety of landscapes and had a variety of lifestyles, it is the osteologist who can provide the data which must precede understanding and explanation of the functioning of the human vertebral column.
Broad explanations of vertebral degeneration have not been provided in this thesis. That would have been impossible. The interplay of morphology and movement has nonetheless been shown to be one basic factor in the processes leading to degeneration in that variants at the thoraco-lumbar transition have been demonstrated to be associated with different patterns of degenerative frequencies.
Apart from a demonstration of this important fact, data have been presented on a range of aspects of the vertebral column and these data are important because they have been collected from a superb sample. If justice has not been done to the sample it is because the methods had to evolve as the study progressed. More information could be extracted from the Kleinburg vertebrae now that a method of study and an understanding of the value of information on vertebrae has been developed. The analysis of vertebrae may be difficult, it may even be tedious, but it is not useless.