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Skeletal Series: The Basic Human Osteology Glossary

19 Dec

Introducing the Human Osteology Glossary

It is important for the budding human osteology student that they understand and correctly apply the basic terms used in the discipline to help identify and describe the skeletal anatomy under study.  Since human osteologists study the skeletal remains of anatomically modern humans (Homo sapiens) the terminology used, specifically the anatomical terminology, has to be precise and correct as befitting the medical use of such terms.

Human osteology remains the foundation on which the disciplines of forensic anthropology and bioarchaeology are built upon, although it is noted that the disciplines can be misleading across international divides.  For example, in the United Kingdom bioarchaeology is still used to refer to the study of both human and non-human skeleton remains from archaeological sites, whilst bioarchaeology in the United States normally refers to human remains only.  It should also be noted here that the other related disciplines, such as palaeoanthropology and biological anthropology, study not just the modern human skeleton but also the skeletal and fossilized remains of extant (genera such as Pan, Pongo and Gorilla) and extinct hominins.  Nevertheless the terminology remains the same when describing the skeletal anatomy of both human and non-human individuals.

Glossary Arrangement

This short glossary is intended to provide a basic introduction to the terminology used in the disciplines that utilizes human osteology as a core focus for the research undertaken.  The terminology documented here also includes a brief description of the word and, where possible, an example of its use.  Primarily the glossary acts as a reference post in order to be used in conjunction with the Skeletal Series posts on this site, which help outline and introduce each skeletal element of the human body section by section and as appropriate.  However please note that the glossary is also arranged in a manner in which it befits the student who needs to quickly scan the list in order to find a specific and relevant word.

Therefore the glossary is arranged in a thematic presentation as follows:

1. Discipline Definitions
2. The Human Body:
– a) Macro
– b) Micro
– c) Growth
– d) Disease and Trauma
3. Anatomical Foundations:
– a) Anatomical Planes of Reference
– b) Directional Terminology
– c) Movement Terminology
4. Postmortem Skeletal Change
– a) Postmortem Skeletal Change

The glossary ends with an introduction to the terminology used to describe the postmortem aspects of body deposition.  This is because it is an important aspect and consideration of any skeletal analysis undertaken.  The terminology used in this section leads away from the strictly anatomical terminology of the sections above it and introduces some terms that are used in archaeology and associated disciplines.

Reference Note

Please note that the bibliography provided indicates a number of important texts from which this glossary was compiled.  The key text books highlighted also introduce the study of the human skeleton, from a number of different perspectives, including the gross anatomical, bioarchaeological and human evolutionary perspectives.  Find a copy of the books at your library or order a copy and become engrossed in the beauty of the bones and the evidence of life histories that they can hold.

The Glossary:

1) – Discipline Definitions

Bioanthropology:  A scientific discipline concerned with the biological and behavioral aspects of human beings, their related non-human primates, such as gorillas and chimpanzees, and their extinct hominin ancestors.  (Related Physical Anthropology).

Bioarchaeology:  The study of human and non-human skeletal remains from archaeological sites.  In the United States of America this term is used solely for the study of human skeletal remains from archaeological sites.

Forensic Anthropology:  An applied anthropological approach dealing with human remains in legal contexts.  Forensic anthropologists often work with coroners and others, such as disaster victim identification teams, in analysing and identifying human remains (both soft and hard tissues) from a variety of contexts including but not limited ID’ing remains from natural disasters, police contexts, war zones, genocides, human rights violations, etc.

Human Osteology:  The study of human skeletal material.  Focuses on the scientific interpretation of skeletal remains from archaeological sites, including the study of the skeletal anatomy, bone physiology, and the growth and development of the skeleton itself.   

Palaeoanthropology:  The interdisciplinary study of earlier hominins.  This includes the study of their chronology, physical structure and skeletal anatomy, archaeological remains, geographic spans, etc. (Jurmain et al. 2011).

Physical Anthropology:  Concerned with the biological skeletal remains of both humans and extant and extinct hominins, anatomy, and evidence of behaviour.  The discipline is often considered congruent with the term bioanthropology, or biological anthropology.  (Related Bioanthropology).

2) a. – The Human Body: Macro

Appendicular Skeleton:  The skeletal bones of the limbs.  Includes the shoulder and pelvic girdles, however it does not include the sacrum.  Skeleton SK423 largely consisted of the non-fragmented disarticulated appendicular elements.

Axial Skeleton:  The skeletal elements of the trunk of the body.  Includes the ribs, vertebrae and sternum.  The body of SK424 was particularly fragmented in-situ, with little sign of excavation or post-excavation damage evidenced on the axial skeleton suggesting fragmentation post-burial.

Cortical (Compact) Bone:  The solid and dense bone found in the bone shafts and on the external surfaces of bone itself.  The cortical bone of the mid-shaft of the right humerus of the tennis player displayed increased thickening.  This is, in this individuals case whose physical history is known, due to the predominance of the right arm during intense and long-term use in physical exercise (see Wolff’s Law). 

Dentin (Dentine):  Calcified but slightly resilient dental connective tissue.  In human growth primary dentin appears during growth whereas secondary dentin forms after the root formation of the tooth is complete (White & Folkens 2005: 421).

Diaphysis:  The shaft portion of a long bone.  The diaphysis of the femur is one of the longest shafts found in the human skeleton, as the femur is the longest bone.

Dry Bone:  Refers to archaeological bone where no soft, or wet, tissue survives, hence the bone is dry.  It should be noted that, when subject to x-rays for investigation, archaeological dry bone radiological images are improved due to a lack of soft tissues obscuring the bone condition.

Elements (Skeletal):  Used to refer to each individual bone.  The human adult body has, on average, 206 individual skeletal elements.

Enamel:  Enamel is an extremely hard brittle material which covers the crown of a tooth.

Endosteum:  A largely cellular membrane that lines the inner surface of bones which is ill-defined (White & Folkens 2005: 421).

Epiphysis:  The epiphysis refers to the often proximal and distal ‘caps’ of long bones that develop from a secondary ossification centre.  The epiphysis of the long bones can, when used in conjunction with other skeletal markers of aging, particularly dentition, provide a highly accurate  age-at-death in non-adult human skeletal remains.

Medullary Cavity:  The cavity found inside the shaft of a long bone.  The medullary cavity of the femur is the site of the longest medullary cavity found in the human body.  The medullary cavity is the location where red and yellow bone marrow is stored and where the red and white blood cells are produced. 

Metaphyses:  The metaphyses refer to the expanded and flared ends of the shaft (or diaphysis) of long bones.  Both the femoral and humeral diaphyses display flared distal metaphyses which are indicative of their anatomical positioning.

Morphology:  The form and structure of an object.  The morphology of the femora is dictated by a variety of factors, not least the size, age, sex and weight of the individual.

Musculoskeletal System:  The musculoskeletal system provides the bony framework of the body in which the muscles attach onto and are able to leverage bones to induce movement.  The musculoskeletal system is responsible for a number of core bodily functions, including blood production and nourishment, alongside providing a stable and safe environment for vital organs.

Osteology:  The scientific study of bone.  Bones form the basis of the skeletal system of vertebrate animals, including humans.  In the United States of America bioarchaeology refers to the study of human bones within an archaeological context.

Periosteum:  The thin dense vascular connective tissue that covers the outer surfaces of bone during life, except on areas of articulation.  The periosteum tissue plays an important part in the maintenance of healthy bone, helping to also provide the body with blood via the bone marrow and associated vessels.  The periosteum provides an important area of osteogensis following a bone fracture.

Postcranial Skeleton:  All bones but the mandible and cranium.  The postcranial skeleton of SK543 was exceptionally well-preserved within the grave context but due to grave cutting the cranium and mandible were completely disturbed and not present within the context recorded.

Trabecular (Spongy) Bone:  Refers to the honeycomb like structure of bone found within the cavity of bones themselves.

2) b. – The Human Body: Micro

Cartilage:  Cartilage is a flexible connective tissue which consists of cells embedded in a matrix.  In the human skeletal system cartilage is found between joints, such as the knee and in forms such as the intervertebral disk in the spine and in the ribcage.  There are three types of cartilage: hyaline, fibrocartilage and elastic cartilage in the human skeletal system, although 28 different types of cartilage have now been identified in the human body as a whole (Gosling et al. 2008:9).

Collagen:  Collagen is a fibrous structural tissue in the skeleton which constitutes up to 90% of bone’s organic content (White & Folkens 2005: 42).

Haversian Canal (Secondary Osteons):  Microscopic canals found in compact, or cortical, bone that contain blood, nerve and lymph vessels, alongside marrow.

Hydroxyapatite:  A dense, inorganic, mineral matrix which helps form the second component of bone.  Together with collagen hydroxyapatite gives bone the unique ability to withstand and respond to physical stresses.

Lamellar (Mature) Bone:  Bone in which the ‘microscopic structure is characterized by collagen fibres arranged in layers or sheets around Haversian canals’ (White & Folkens 2005: 423).  Lamellar bone is mechanically strong.  Related woven (immature) bone.

Osteoblast:  Osteoblasts are the ‘bone-forming cells which are responsible for synthesizing and depositing bone material’ (White & Folkens 2005: 424).

Osteoclast:  Osteoclasts are the cells responsible for the resorption of bone tissue.

Osteocyte:  Osteocytes are the living bone cell which is developed from an osteoblast (White & Folkens 2005: 424).

Osteon:  The osteon is a Haversian system, ‘a structural unit of compact bone composed of a central vascular (Haversian) canal and the concentric lamellae surrounding it; a Primary Osteon is composed of a vascular canal without a cement line, whereas the cement line and lamellar bone organized around the central canal characterize a Secondary Osteon‘ (White & Folkens 2005: 424).

Remodeling:  Remodeling is the cyclical process of bone resorption and bone deposition at one site.  The human skeleton continually remodels itself throughout life, and after full growth has been achieved towards the end of puberty.  Further to this bone is a tissue that responds to physical stress and remodels as appropriate. 

Woven (Immature) Bone:  characterized by the haphazard organisation of collagen fibres.  Primarily laid down following a fracture and later replaced by lamellar bone.  Woven bone is mechanically weak.  Related lamellar (mature) bone.

2) c. – The Human Body: Growth

Appositional Growth:  The process by which old bone that lines the medullary cavity is reabsorbed and new bone tissue is grown beneath the periosteum, which increases the bone diameter.

Endochondral Ossification:  One of two main processes of bone development in which cartilage precursors (called cartilage models) are gradually replaced by bone tissue (White & Folkens 2005: 421).

Epiphyseal (Growth) Plate:  The hyaline cartilage plate found at the metaphyses of the long bones during growth of the individual (i.e. non-adults), where bone growth is focused until full growth cycle has been completed.

Idiosyncratic:  Referring to the individual.  The normal morphology of the human skeleton, and its individual elements, is influenced by three main factors of variation: biological sex (sexual dimorphism), ontogenetic (age), and idiosyncratic (individual) factors.

Intramembranous Ossification:  One of two main processes of ‘bone development in which bones ossify by apposition on tissue within an embryonic connective tissue membrane’ (White & Folkens 2005: 422).

Ontogeny:  The growth, or development, of an individual.  Ontogeny can be a major factor in the morphological presentation of the human skeleton.

Osteogenesis:  The formation and development of bone.  Embryologically the development of bone ossification occurs during two main processes: intramembranous and endochondral ossification.

Wolff’s Law:  Theory developed by German anatomist and surgeon Julius Wolff (1836-1902) which stated that human and non-human bone responded to the loads, or stresses, under to which it is placed and remodels appropriately within a healthy individual.

Sexual Dimorphism:  The differences between males and females.  The human skeleton has, compared to some animal species, discrete differences in sexual dimorphism; however there are distinct functional differences in the morphology of certain elements which can be used to determine biological sex of the individual post-puberty.

2) d. – The Human Body: Disease and Trauma

Atrophy:  The wastage of an organ or body tissue due to non-use.  Atrophy can be an outcome of disease processes in which the nerves are damaged, leading to the extended, or permanent, non-use of a limb which can lead to muscle wastage and bone resorption.

Blastic Lesion: Expansive bone lesion in which bone is abnormally expanded upon as part of part of a disease process.  The opposite of lytic lesion.

Calculus: Tartar; a deposit of calcified dental plaque on the surface of teeth.  The calculus found on the teeth of the archaeological skeleton can contain a wealth of information on the diet and extramasticatory activities of the individual.

Callus:  The hard tissue which is formed in the osteogenic (bone cell producing) layer of the periosteum as a fracture repair tissue.  This tissue is normally replaced by woven bone, which is in turn replaced by lamellar (or mature) bone as the bone continues to remodel during the healing process.

Caries:  Caries are ‘a disease characterized by the ‘progressive decalcification of enamel or dentine; the hole or cavity left by such decay’ (White & Folkens 2005: 420).  The extensive caries present on the 2nd right mandibular molar of Sk344 nearly obliterates the occlusal (chewing) surface of the tooth.

Compound Fracture:  A fracture in which the broken ends of the bone perforate the skin.  A compound fracture can be more damaging psychologically to the individual, due to the sight of the fracture itself and soft tissue damage to the skin and muscle.  Compound fractures also lead to an increased risk of fat embolism (or clots) entering the circulatory system via marrow leakage, which can be potentially fatal.

Dysplasia:  The abnormal development of bone tissue.  The bone lesions of fibrous dysplasia display as opaque and translucent patches compared to normal healthy bone on X-ray radiographic images.

Eburnation: Presents as polished bone on surface joints where subchondral bone has been exposed and worn.  Osteoarthritis often presents at the hip and knee joints where eburnation is present on the proximal femoral head and distal femoral condyle surfaces, alongside the adjacent tibia and iliac joint surfaces.

Hyperostosis:  An abnormal growth of the bone tissue.  Paget’s disease of bone is partly characterized by the hyperostosis of the cranial plates, with particularly dense parietal and frontal bones.

Hyperplasia:  An excessive growth of bone, or other, tissues.

Hypertrothy:  An increase in the volume of a tissue or organ.

Hypoplasia:  An insufficient growth of bone or other tissue.  Harris lines are dense transverse lines found in the shafts of long bones, which are indicative of arrested growth periods, as non-specific stress events, in the life of the individual.  Harris lines can often only be identified via X-ray radiography or through visual inspection of internal bone structure.

Lytic Lesion:  Destructive bone lesion as part of a disease process.  The opposite of a blastic lesion.  Syphilitic lytic bone lesions often pit and scar the frontal, parietal and associated facial bones of the skull.

Osteoarthritis:  Osteoarthritis is the most common form of arthritis, which is characterized by the destruction of the articular cartilage in a joint.  This often leads to eburnation on the bone surface.  Bony lipping and spur formation often also occur adjacent to the joint.  This is also commonly called Degenerative Joint Disease (DJD) (White & Folkens 2005: 424).

Osteophytes:  Typically small abnormal outgrowths of bone which are found at the articular surface of the bone as a feature of osteoarthritis.  Extensive osteophytic lipping was noted on the anterior portion of the vertebrae bodies of T2-L3 which, along with the evidence of eburnation, bony lipping and spurs presenting bilaterally on the femora and tibiae, present as evidence of osteoarthritis in SK469.

Pathognomonic:  A pathological feature that is characteristic for a particular disease as it is a marked intensification for a diagnostic sign or symptom.  A sequestrum (a piece of dead bone that has become separated from normal, or healthy, bone during necrosis) is normally considered a pathgonomic sign of osteomyelitis. 

Pathological Fracture:  A bone fracture that occurs due to the result of bones already being weakened by other pathological or metabolic conditions, such as osteoporosis (White & Folkens 2005: 424).

Palaeopathology:  The study of ancient disease and trauma processes in human skeletal (or mummified) remains from archaeological sites.  Includes the diagnosis of disease, where possible.  A palaeopathological analysis of the skeletal remains of individuals from the archaeological record is an important aspect of recording and contextualising health in the past.

Periodontitis:  Inflammation around the tissues of a tooth, which can involve the hard tissues of the mandibular and maxilla bone or the soft tissues themselves.  Extensive evidence of periodontitis on both the mandible and maxilla suggests a high level of chronic infection.

Periostitis: The inflammation of the periosteum which is caused by either trauma or infection, this can be either acute or chronic.  The anterior proximal third of the right tibia displayed extensive periostitis suggesting an a persistent, or long term, incidence of infection.

Radiograph:  Image produced on photographic film when exposed to x-rays passing through an object (White & Folkens 2005: 425).  The radiographic image of the femora produced evidence of Harris lines which were not visible on the visual inspection of the bones.

3) a. – Anatomical Planes of Reference

Anatomical Position (Standard):  This is defined as ‘standing with the feet together and pointing forward, looking forward, with none of the leg bones crossed from a viewer’s perspective and palms facing forward’ (White & Folkens 2005: 426).  The standard anatomical position is used when referring to the planes of reference, and for orientation and laying out of the skeletal remains of an individual for osteological examination, inventory, and/or analysis.

Coronal (frontal/Median):  The coronal plane is a vertical plane that divides the body into an equal forward and backward (or anterior and posterior) section.  The coronal plane is used along with the sagittal and transverse planes in order to describe the location of the body parts in relation to one another.

Frankfurt Horizontal:  A plane used to systematically view the skull which is defined by three osteometric points:  the right and left porion points (near the ear canal, or exterior auditory meatus) and left orbitale.

Oblique Plane:  A plane that is not parallel to the coronal, sagittal or transverse planes.  The fracture to the mid shaft of the left tibia and fibula was not a transverse or spiral break, it is an oblique fracture as evidenced by the angle of the break. 

Sagittal:  A vertical plane that divides the body into symmetrical right and left halves.

Transverse:  Situated or extending across a horizontal plane.  A transverse fracture was noted on the midshaft of the right femur.  The fracture was indicative of a great force having caused it, likely in a traumatic incident.

3) b. – Anatomical Directional Terminology

Superior:  Superior refers towards the head end of the human body, with the most superior point of the human body the parietal bone at the sagittal suture (White & Folkens 2005: 68).

Inferior:  Inferior refers towards the foot, or the heel, which is the calcaneus bone.  Generally this is towards the ground.  The tibia is inferior to the femur.

Anterior:  Towards the front of the body.  The sternum is anterior to the vertebral column.

Posterior:  Towards the back of the body.  The occipital bone is posterior to the frontal bone of the cranium.

Proximal:  Near the axial skeletonThe term is normally used for the limb bones, where for instance the proximal end of the femur is towards the os coxa.

Medial:  Towards the midline of the body.  The right side of the tongue is medial to the right side of the mandible.

Lateral:  The opposite of medial, away from the midline of the body.  In the standard anatomical position the left radius is lateral to the left ulna.

Distal:  furthest away from the axial skeleton; away from the body.  The distal aspect of the humerus articulates with the proximal head of the radius and the trochlear notch of the ulna.

Internal:  Inside.  The internal surface of the frontal bone has the frontal crest, which is located in the sagittal plane.

External: Outside.  The cranial vault is the external surface of the brain.

Endocranial:  The inner surface of the cranial vault.  The brain fills the endocranial cavity where it sits within a sack.

Ectocranial:  The outer surface of the cranial vault.  The frontal bosses (or eminences) are located on the ectocranial surface of the frontal bone.

Superficial:  Close to the surface of the body, i.e. towards the skin.  The bones of the cranium are superficial to the brain.

Deep:  Opposite of superficial, i.e. deep inside the body and far from the surface.  The lungs are deep to the ribs, but the heart is deep to the lungs.

Palmar:  Palm side of the hand.  The palm side of the hand is where the fingers bear fingerprints.

Plantar:  The plantar side of the foot is the sole.  The plantar side of the foot is in contact with the ground during normal ambulation.

Dorsal:  Either the top of the foot or the back of the hand.  The ‘dorsal surface often bears hair whilst the palmar or plantar surfaces do not’ (White & Folkens 2005: 69).

3) c. – Anatomical Movement Terminology

Abduction:  Abduction is a laterally directed movement in the coronal plane away from the sagittal, or median, plane.  It is the opposite of adduction.  Standing straight, with the palm of the left hand anterior, raise the left arm sideways until it is horizontal with the shoulder: this is the action of abducting the left arm.

Adduction:  Adduction is the medially directed movement in the coronal plane towards the sagittal, or median, plane.  It is the opposite of abductionStanding straight, with the palm of the right hand anterior, and the right arm raised sideways until it is horizontal with the shoulder, move the arm down towards the body.  This is adduction.

Circumduction:  Circumduction is a ‘circular movement created by the sequential combination of abduction, flexion, adduction, and extension’ (Schwartz 2007: 373).  The guitarist who performs the action of windmilling during playing is circumducting their plectrum holding limb.

Extension:  Extension is a movement in the sagittal plane around a transverse axis that separates two structures.  It is the opposite of flexionThe extension of the forearm involves movement at the elbow joint.

Flexion:  A bending movement in the saggital plane and around a transverse axis that draws two structures toward each other (Schwartz 2007: 374).  It is the opposite of extensionThe flexion of the forearm involves movement at the elbow joint.

Lateral Rotation:  The movement of a structure around its longitudinal axis which causes the anterior surface to face laterally.  It is the opposite of medial rotation.

Medial Rotation:  The movement of a structure around its longitudinal axis that causes the anterior surface to face medially.  It is the opposite of lateral rotation (Schwartz 2007: 376).

Opposition: The movement of the ‘thumb across the palm such that its “pad” contracts the “pad” of another digit; this movement involves abduction with flexion and medial rotation’ (Schwartz 2007: 377).

4) a. – Postmortem Skeletal Change

Antemortem:  Before the time of death.  The evidence for the active bone healing on both the distal radius and ulna diaphyses, with a clean fracture indicating use of a bladed instrumented, suggests that amputation of the right hand occurred antemortem. 

Bioturbation:  The reworking of soils and associated sediments by non-human agents, such as plants and animals.  Bioturbation can lead to the displacement of archaeological artefacts and structural features and displace deposited human skeletal bone.  Evidence of bioturbation in the cemetery was noted, as irregular tunnels were located across a number of different grave contexts suggesting the action of a burrowing or nesting mammal.  This led to the disarticulation of skeletal material within the grave contexts themselves which, on first investigation, may have led to an incorrect analysis of the sequence of events following the primary deposition of the body within the grave.

Commingled:  An assemblage of bone containing the remains of multiple individuals, which are often incomplete and heavily fragmented.  The commingled mass grave found at the Neolithic site of Talheim, in modern southern Germany, suggest that, along with the noted traumatic injuries prevalent on the individuals analysed, rapid and careless burial in a so-called ‘death pit’ took place by the individuals who carried out the massacre.  The site is a famous Linearbandkeramik (LBK) location which dates to around 5000 BC, or the Early European Neolithic.  Similar period mass burials include those at Herxheim, also in Germany, and Schletz-Asparn in nearby Austria.

Diagenesis:  The chemical, physical, and biological changes undergone by a bone through time.  This is a particularly important area of study as the conservation of bones must deal with bacteria and fungal infection of conserved bone if the skeletal material is to be preserved properly.  Analysis of the diagenesis of skeletal material can also inform the bioarchaeologist of the peri and postmortem burial conditions of the individual by comparing the environmental contexts that the bone had been introduced to.

Perimortem: At, or around, the time of death.  The decapitation of SK246 occurred perimortem as evidenced by the sharp bladed unhealed trauma to the associated body,  pedicles, lamina and spinal arches of the C3 and C4 vertebrae.

Postmortem: Refers to the period after the death of the individual.  It is likely that the body had been moved postmortem as indicated by position of the body in the bedroom and by the extensive markers on the skin, suggesting physical manipulation and accidental contusions.  Further to this the pooling of the blood within the first few hours postmortem was not indicative of where the body was located at the time of discovery.

Postmortem Modification:  Modifications, or alterations, that occur to the skeletal remains after the death of the individual.  No postmortem modification of the skeletal elements of SK543 was noted, however extensive evidence of bioturbation in the form of root action was noted on across the majority (> 80%) of the surface of the surviving skeletal elements recovered.

Taphonomy:  The study of processes that can affect the skeletal remains between the death of the individual and the curation, or analysis, of the individual.  There are a variety of natural and non-natural taphonomic processes that must be considered in the analysing of human skeletal material from archaeological, modern and forensic contexts.  This can include natural disturbances, such as bioturbation, or non-natural, such as purposeful secondary internment of the body or skeletal remains.

Note on the Terminology Used & Feedback

The terminology used above, and their definitions, are taken in part from the below sources.  Direct quotations are referenced to the source and page.  They, the sources in the bibliography, are a small handful of some of the exceptional books available which help to introduce the human skeletal system and the importance of being able to identify, study and analyse the bones in a scientific manner.  The human skeletal glossary present here is subject to revision, amendments and updates, so please do check back to see what has been included.  Finally, I heartily advise readers to leave a comment if revisions, or clarifications, are needed on any of the terms or definitions used in the glossary.

Bibliography & Further Reading

Gosling, J. A., Harris, P. F., Humpherson, J. R., Whitmore, I., Willan, P. L. T., Bentley, A. L., Davies, J. T. & Hargreaves, J. L. 2008. Human Anatomy: Colour Atlas and Texbook (5th Edition). London: Mosby Elsevier.

Jurmain, R., Kilgrore, L. & Trevathan, W. 2011. Essentials of Physical Anthropology. Belmont: Wadsworth.

Larsen, C. S. 1997. Bioarchaeology: Interpreting Behaviour from the Human Skeleton. Cambridge: Cambridge University Press.

Lewis, M. E. 2007. The Bioarchaeology of Children: Perspectives from Biological and Forensic Anthropology. Cambridge: Cambridge University Press.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease (3rd Edition). Stroud: The History Press.

Schwartz, J. H. 2007. Skeleton Keys: An Introduction Human Skeletal Morphology, Development, and Analysis (2nd Edition). New York: Oxford University Press.

White, T. D. & Folkens, P. A. 2005. The Human Bone Manual. London: Elsevier Academic Press.

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Bone Benefits of 3D Printing

24 Mar

Recently there has been some extraordinarily interesting articles in the press on the value of 3D printing in surgical procedures.  In particular the United Kingdom seems to be leading the way in producing and using 3D printed implants for use in reconstructive surgeries, as recent articles in the BBC, the Daily Telegraph and The Independent publications highlight.

Mr Craig Gerrand, a consultant orthopaedic surgeon in an NHS hospital in Newcastle-Upon-Tyne, England, recently announced the success of producing and fitting half of a 3D printed titanium hip into an unnamed patient who was suffering from chondrosarcoma.  Chondrosarcoma is a cancer of the cartilage cells and typically tends to affect the axial skeleton.  In this case the unnamed patient suffered severe damage to one half of his hip due to the effect of the destructive cancer.  In an effort to stop the spread of the cancer, which rarely responds to radiotherapy or chemotherapy, the surgeon was forced to remove half of the patient’s hip (termed an hemipelvectomy, which can be external or internal dependent on if the leg is to be amputated as well).

Before this, however, Mr Gerrand was able to construct and print a 3D titanium half model of the patient’s  hip which, along with the added attachment of a hip socket replacement, he was then able to implant into the patient following the removal of the chondrosarcoma affected bone.  The fake hip was based on scans and x-rays of the patient’s own hip for anatomical reasons and was fully produced using a 3D printer.  The printer used lasers to fuse together titanium powder, which slowly built up a model of the hip layer by layer.  The fake hip was then coated in a mineral into which the remaining bone in the patient’s healthy hip could fuse with, providing long-term stability during recovery and mobility.  Although the news articles on the case were only recently produced, the actual surgery itself was carried out over 3 years ago.  Wonderfully the patient continues to manage to walk with mobility aids, something that would be unthinkable if the surgeon had not been able to print and implant the titanium hip.

In other news recently, as reported by the BBC, the Welsh victim of a vicious motorcycle accident was able to benefit from the 3D printing of custom parts for use in maxillofacial reconstruction.  The use of 3D printing was used at each stage of the procedure, including the planning of the surgery and the reconstruction itself, by using titanium parts to stabilise or replace parts of the patient’s own facial bones.

Following the motorcycle accident, which severely damaged both of the patient’s zygomatic bones as well as sustaining damage to the maxilla, frontal and nasal bones, the patient’s face was reconstructed in a series of operations.  To achieve the aim of improving the patient’s face to almost pre-accident standards the surgeons scanned the skull of the individual using a CT scanner and printed the results using a 3D printer, the results of which helped to produce a symmetrical model of his skull to help plan the surgery in detail.  By using cutting guides and by being able to measure the facial skeletal anatomy directly, they managed to print titanium plates to match the symmetry of the patient’s face originally, and likely minimised the time the patient spent under anesthetic.  In the article the patient, from the city of Cardiff in Wales, movingly states how he now looks as he did before the motorcycle accident, adding that he was able to go out in public once again following the reconstructive surgery.

titaniummodelskullprinted

A model example of how the surgeons helped plan the surgery to improve the motorcycle accident man’s face with 3D printed titanium implants. The image shows the left zygomatic arch with the titanium implants in white against the model of the cranium. (Image credit: The BBC 2014).

The two innovative procedures above are fine examples of the value of integrating the latest technology into the operating theatre, but they also highlight some themes of the body and surgical intervention that interest me.  The benefits of being able to 3D print specific and specially made parts offer a ‘continuation’ for the patient of their own bodies, even with the distinct disconnect (and often intrusive procedures) between the effect of the trauma or disease process and the reconstructive attempts at re-structuring the body, as highlighted in the above orthopaedic cases.

3D printing is a fast-moving technology in the medical world, where even the possibility of being able to bioprint human organs and tissue is fast becoming a possibility for the future.  Perhaps most significantly it offers the option for the patient to use their own bodies (or, more specifically, their cells) to help cultivate a ‘second chance’ organ or tissue in the lab using artificial scaffolds to grow the tissue needed.  To a small degree this has already been carried out with certain tissues, but further work is needed to be able to bioprint human organs properly.  But back to the use of 3D printing in orthopaedic surgery.

Reconstructive orthopaedic surgery generally aims to improve the quality of life for the individual through physical manipulation and internal or external fixation of an implant onto, or into, the bone directly.  The benefits of this are not just anatomical but often also psychological, perhaps more so in maxillofacial procedures.  The patient may feel that their appearance has improved dramatically, or that they have been made to look more normal.  This can increase the positive social perception of the patient themselves and boost self-confidence.  Of course there are always risks associated with reconstructive orthopaedic surgery, the first and foremost being the fact that more damage may occur as a result of the often intrusive procedures, particularly the risk of implant fatigue and possibility of macro/micro fracture of surrounding bone material.

Internal and external fixations also often run the risk of infection, more so when there is the risk of repeated surgical interventions.  Internal fixation (such as intramedullary rodding) has the possibility of deep bone infection, whilst external fixation (such as the use of the Ilizarov frame) often results in small localised infections.  Nevertheless the risk of infection by implant is often controlled for by using clean surgical rooms, sterilised medical equipment and the infusion of antibiotics during and post-surgery.  Further to this, antibiotic laden cement is also often used during the surgical fixation of an implant as an added protector against infection through the introduction of foreign bodies.

I am also interested in the after effects of surgery in the perception of the self.  Titanium implant parts are typically manufactured for general use, although there is a dizzying variety of screws, plates and rods available to the orthopaedic surgeon.   Of course they are also shaped and made to fit the patient to a certain degree.  Titanium is a fairly hefty metal, with the patient often being able to tell that something heavy has been implanted into the body upon awakening from surgery.  It also often hammered or screwed into the bone, sometimes causing the bone to fracture or microfracture during the process, or afterwards as the patient starts to weightbear.  (As a side note orthopaedic surgeons are often built like rugby players because of the demanding physical aspect of orthopaedic surgery).

The new generation of 3D printed parts are often made of different materials than purely consisting of titanium.  Importantly there is the option to help improve the post surgical integration of existing bone and ceramic implants (such as hip replacements, which often use ceramic femoral heads) through the ability to print intricate designs to help meld with bone, and the ability to seed the ceramic scaffolds with the patients own cultured cells to promote  healthy bone growth (Seitz et al. 2005).  This is purely speculation and conjecture, but I wonder if the newer materials used, are of a much lighter material than titanium and are, as a result, less intrusive to the person undergoing the surgery?

What the 3D printing of implants offer is the opportunity to make identical and specifically made models of the  patient for their own use (Fedorovich et al. 2011), by either basing the custom build on an existing bone of the patient or by specifically making a part to improve what has either been lost to a disease process or a traumatic incident, to name the two main causes for orthopaedic reconstructive surgery.  There are also opportunities to help promote wound healing and prevent infection during and post-surgery (Lee et al. 2012), a step that is needed considering the rise of drug resistant germs, the general decline in pharmaceutical companies producing new antibiotics, and the widespread misuse of antibiotics in general (Mayo Clinic release).  3D printing then, I believe, is an important step in advancing and improving the techniques, approaches and materials used in orthopaedic surgery.

Learn More

  • Watch Ben Garrod’s Secrets of Bones BBC TV series to learn more about just how wonderful the skeleton is.  Learn more about the remarkable 3D print of his skull here.
  • Kristina Killgrove, over at Powered by Osteons, has a series of posts on her attempts to integrate 3D printing with teaching human osteology, check it out here.
  • The frankly amazing news of the Netherlands surgeons who were able to produce a 3D model of a patient’s cranium which was then successfully implanted can be found here, although there has been a lack of evidence for this procedure in other mainstream or medical publications.

Bibliography

Fedorovich, N. E., Alblas, J., Hennink, W. E., Oner, F. C. & Dhert, W. J. A. 2011. Organ Printing: The Future of Bone Regeneration? Trends in Biotechnology29 (12): 601-606.

Lee, J-H., Gu, Y. Wang, H. & Lee, W. Y. 2012. Microfluidic 3D Bone Tissue model for High-Throughput Evaluation of Wound-Healing and Infection-Preventing Biomaterials. Biomaterials. 33 (4): 999-1006.

Seitz, H., Rieder, W., Irsen, S., Leukers, B. & Tille, C. 2005. Three-Dimensional Printing of Porous Ceramic Scaffolds for Bone Tissue Engineering. Journal of Biomedical Materials Research Part B: Applied Biomaterials. 74B (2): 782-788.

Skeletal Series Part 4: The Human Spine

30 Apr

As we started with the skull in this series of posts, we shall continue with the axial skeleton, and discuss the vertebral column (or spine) in the human skeleton.  The human spine consists of vertebrae that help support the back muscles, protect the spinal column, and provides the rod function for the axial skeleton (Mays 1999).  We’ll firstly discuss the moveable vertebrae, then move onto the hyoid, sacrum and coccyx elements.

On a personal note, I have difficulty with identifying vertebrae and reconfiguring them in the right order.  This is something I’m hoping to improve soon!  Meantime, here is a short guide…

As the basic excavation methods have already been discussed in the previous post, we will miss them out here.  Once again, care should be taken with handling, and it is unlikely all the elements would survive.  The hyoid bone is particularly liable to be missing or broken as it is a fairly small and fragile bone (Larsen 1997).

Vertebrae Anatomy, Terminology and Elements

The human spine consists of 33 vertebrae in total; 24 are considered to be part of the upper spine, whilst the other 11 are found in the Sacrum & Coccyx (discussed below).  The 24 vertebrae can be split into three separate groups based on morphology, spinal curvature and position; those of the Cervical, Thoracic & Lumbar vertebrae (White & Folkens 2005).  The vertebrae are often referred to by their first distinction, and by the number in that area.  So the second cervical vertebrae is referred to as the C2 etc.

The main bone landmark features of a typical vertebra are presented in the diagram below.  Please note that there are variations depending on the class of vertebrae under discussion.

Typical bone landmarks found on vertebrae and anatomical information (Eckalbar et al 2012. Scoliosis and Segmentation Defects of The Vertebrae. Developmental Biology. 1 (3): 402.)

The vertebrae in these groups are typically found as below (proximal to distal):

Cervical: 7 Vertebrae present.  The normal cervical vertebrae include interlocking vertebral bodies, with saddle shaped superior and inferior surfaces; alongside this the canal (see below) is triangular and of a similar size to the vertebral body (Mays 1999).  The spinous process are shorter than in thoracic and not as massive as lumbar vertebrae processes (White & Folkens 2005: 163).

Thoracic: 12 Vertebrae present.  The elements in this section of spine again increase in body size (vertebral body).  Each thoracic element articulates with a pair of ribs in the human skeleton.  It has been noted that ‘upper thoracic bodies are roughly triangular in a superior outline whilst the lower thoracic vertebral bodies are more circular’ (White & Folkens 2005: 170).  The vertebrae canal (or arch which the spinal column runs through posteriorly) are smaller relative to the vertebral body, and importantly, more circular than in cervical vertebrae (Waldron 2009).

Lumbar: 5 Vertebrae present.   Finally the vertebral bodies of the lumbar vertebrae once again increase in size from superior to inferior (as all vertebrae do).  They are the largest of all the unfused vertebrae, and should be easily identifiable by their size and features (larger spinous process, vertebral bodies, & smaller transverse process and lumbar arches) (White & Folkens 2005: 178).

It must be remembered that due to variation, an added or missing vertebra, is a possibility.  Between the individual vertebrae bones are intervetebral discs present.  In life, they help to provide movement between bones and act as ligaments.

Cervical, Thoracic & Lumbar Vertebrae & Anatomical Features.

As discussed above, there are three vertebrae types, as seen in the diagram above and below.  Important changes in the morphology and shape of these elements can be noted, thus each part can be ascertained to the differing thirds of the spine (White & Folkens 2005).  As it can be seen from the diagram below, the thoracic & lumbar vertebrae have a much more developed Vertebral Body (cementum in other animals), alongside a much more elongated Spinous Process.

Differences In Body Shape for Cervical (C4), Thoracic (T6) & Lumbar (L2) Vertebrae.

Distinctive Elements

The Atlas and Axis Vertebrae (diagram below), the first and second cervical vertebrae, are the most distinctive in terms of size and morphology.  The Atlas bone (C1) lies between the cranium (connecting with the condyles of the occipital bone) and the Axis  vertebrae (C2).  The atlas lacks a ‘vertebral body, a spinous process and has no articular disks either superior or inferior to it’ (White & Folkens 2005: 163).  The Axis bone also lacks a typical vertebral body.  It’s most distinctive feature is the odontoid peg, as seen in the diagram below.  This allows the head to rotate, moving the atlas about the odontoid peg of the axis bone (White & Folkens 2005: 169).

Features Of The Atlas (C1) & (C2) Axis Vertebrae

Transitional vertebrae include the sixth cervical vertebrae, which has a larger cementum (body) and a spinous process resembling a thoracic vertebrae.  The twelfth thoracic vertebrae resembles the eleventh vertebrae but the inferior articular facets assume the lumbar pattern rather than the typical thoracic pattern (White & Folkens 2005: 170).

The Hyoid bone (diagram below) is the located in the neck, immediately above the Adams apple on the anterior surface of the neck.  it is the only bone in the human body that does not articulate with any other bone whatsoever.  It consists of the body, the lesser horns and greater horns, as can be discerned in the diagram below (White & Folkens 2005: 155).  Unfortunately, it is often broken (fractured) during strangulation, and can be used as key indicator in murder cases.

Details of The Hyoid Bone

The Sacrum (diagram below) consists of five fused vertebrae in a wedge like shape at the bottom of the vertebral column.  These fuse in adolescents, and can consists of between four to six segments, although five is the normal average.  To both lateral sides are the pelvic bones (Os Coxa), whilst inferiorly lies the coccyx.

The Coccyx (diagram below) articulates distally to the Sacrum, and consists of 3 to 5 fused elements (variation is common).  It is the vestigial tail, and highly variable in shape.  In later life, the Coccyx may fuse to the Sacrum.  As with the above bone, the coccyx decreases in size inferiorly (White & Folkens 2005: 245).

Sacrum Terminology

Discussion of Osteoarthritis

As biped hominids, homo sapiens are at the mercy of numerous back problems.  The wear and tear, stresses and strains, that the vertebrae have to take are often manifested through various disease & maladies (Jurmain et al 2010).  Specifically, there is an increased susceptibility  in spinal joint disease.  Osteoarthritis is one such example, (OA) presenting in vertebrae that often occurs as a direct response to spinal stress (Roberts & Manchester 2010: 139).  The spine is recognised as ‘exhibiting a backward curve in the chest or thoracic region and a forward curve in the lumbar and cervical regions’; which lead to the C5, T8 & L4 vertebrae as being the most affected by joint disease (Roberts & Manchester 2010: 139).

These points are the areas of maximum and minimum stress, and this is seen as the variation in the frequency of OA in the spinal column.  As Waldron (2009: 27-30) states, ‘osteoarthritis is primarily a disease of the articular cartilage which breaks down as the disease progresses’.  The incipient factor is the enzymatic breakdown of the cartilage matrix, and affects the bone in the following ways.

The five main steps are outlined below:

1.  ‘Formation of new bone (after mixed signals from enzymes) around the margins of the joint; often called marginal ostephytes.

2.  Formation of new bone on the joint surface due to the vascularisation of the subchondral bone.

3. Pitting on the joint surface manifested as a series of holes on the joint surface.

4.  Changes in the normal contour of the joint, often widening and flattening of he contour.

5.  The production of eburnation, a highly polished area on the joint surface, usually sharply demarcated from the non-eburnated surface.  This area is sometimes grooved towards the motion and direction of the joint; presumably due to debris or crystals between the two articulating surfaces’ (Waldron 2009: 27-29).

Eburnation On The ‘Peg’ of the Axis Vertebrae (Shiny & Smooth Wearing)

Factors that are known to be important as precipitates to OA include age, race, sex, genetics, obesity, trauma and most importantly, movement itself.  Age is particularly important, as at the older standard range of human health there is scarcely anyone left with normal joints (Roberts & Manchester 2010, Waldron 2009).  An example of OA occurring in populations will now be discussed.  Lovell (1994) discuss a site in Pakistan, dating from 4000-5000 years ago (Bronze Age), where a pattern of OA was seen in the population.  The disease was noted as mechanical in nature (as normal), but focused on the cervical vertebrae.  This may be a reflection of activity in which the people carried heavy loads upon their heads (Roberts & Manchester 2010: 141).

The excavation of medieval rural site of Wharram Percy, in North Yorkshire, uncovered a large series population (May 1999).  Examination of features on the spinal column indicate OA was prevalent in the population at around 55 per cent for males and 39 per cent for females.  Because the site was rural in nature, and had indication of being used as an agricultural centre, it was identified that this population had developed OA through their lifestyle choices (Roberts & Manchester 2010: 143).  Useful as these sites, and features are, it should be reminded that ‘spinal joint disease was not the ideal part of the skeleton to observe as a marker of activity-related stress’ (Roberts & Manchester 2010: 143).

Bibliography

Jurmain, R. Kilgore, L. & Trevathan, W.  2011. Essentials of Physical Anthropology International Edition. London: Wadworth.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Waldron, T. 2009. Palaeopathology: Cambridge Manuals in Archaeology. Cambridge: Cambridge University Press.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.