Pathology of the week: Congenital fusion/vertebral shifts

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This is a cranium from the medieval cemetery St. Helen-on-the-Walls, York. We would like to thank the Yorkshire Museum for the access to this specimen.

Cranium and first cervical vertebra

The atlas (first cervical vertebra) is fused to the occipital in a fixed, slightly rotated position to the right side. This fusion occurs through the occipital condyles and bony bridges between the anterior arch of the atlas to the basilar part of the occipital and between the posterior margin of the transverse processes of the occipital to an area adjacent to the posterior edge of the occipital condyles.  A triangular exostosis projects c. 4-5mm into the foramen magnum from the left occipital condyle.  Viewed from the foramen magnum, interruptions are visible in the superior half of the anterior arch and the superior articular surface of the atlas.  Similarly, posterior to the occipital condyles are interruptions in the surface, spicular compact bone formation, and depressions.  This may be the expression of a occipital vertebra (Barnes: 83).

The cranial base and viscerocranium are asymmetric. Significantly, the right orbit is higher in position by 2.1mm and there is a posterolateral rotation of the viscerocranium of 7mm to the right.  The right mastoid process is 2.2mm larger in length and situated 4.6mm further from the centre of the cranial base. The left side of the occipital and posterior parietal is flattened, while the right side is bulbous.  This asymmetry is due to positional torticollis as a result of congenital fusion of the atlas to the occipital.

Co-existing Pathology:

The mandibular fossae have large osteolytic lesions located laterally on the anterior slope.  The anterior slopes also have multiple shallow linear grooves and new compact bone formation.

References Cited:

Barnes E. 1994. Developmental defects of the axial skeleton in paleopathology. Niwot: University of Colorado Press.

Disease Classification:

Developmental-hyperplastic-congenital fusion

Developmental-dysplastic-vertebral shifts


Miscellaneous-skeletal-temporomandibular joint disease

Miscellaneous-dental-ante-mortem tooth loss

A placement student’s reflections



Over the course of the Digitised Diseases project we have been very fortunate to have had the help of some truly awesome placement students in the BARC and in the Centre for Visual Computing.

Our latest two placement students in the BARC, Andrew Douthwaite and Zoe Meacock have been no exception. Andrew and Zoe have been crucial in supporting Digitised Diseases in the very late stage of the project. Andrew has written the following about his time on placement and his involvement in Digitised Diseases:

“As a placement students we were involved in day-to-day tasks within the Biological Anthropology Research Centre at the University of Bradford, helping out as and when people needed us, but as well as that we had our “go to Jobs”, checking, labelling and re-bagging and labelling the Hereford skeletal collection.

BARC placement students, Andrew and Zoe check and re-bag skeletal material from Hereford Cathedral

BARC placement students, Andrew and Zoe check and re-bag skeletal material from Hereford Cathedral

For the Digitised Diseases project, Zoe and I scanned radiographs from both BARC and RCS collections and photographed a wide variety of elements, ranging from metatarsals and phalanges to crania and mandibles. These photographs were sent, along with laser scans, to allow the texturing of 3D models. Once the specimens had been fully processed, it was our job to return them to their proper place in the collection. Although this was relatively simple some sites posed more of a challenge than others in the location of specific individuals, namely Eccles! [The Eccles collection has an…idiosyncratic skeletal numbering system – Ed]

A tricky job was keeping track of bones that were still needed for the project, especially during the teaching term as they would be taken out for lab sessions. The easiest way of doing this was to create a chart in which the details such as site, skeleton number, element, the room and box which the bone had come from, date of removal and return were noted down so that everything would get back to its proper place.

I very much enjoyed my time at BARC and have gotten a great deal out of this placement. I have gained skills and experience that I didn’t have before, such as photography, and a much more in depth knowledge of the human skeleton and how it can be affected by both disease and the burial environment”.

On behalf of the entire Digitised Diseases team we thank all of our placement students for their hard work.

Pathology of the Week

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This is the tenth thoracic vertebra and rib from an individual from Westness, Orkney with as yet an undiagnosed pathology.  Any suggestions would be much appreciated.

Tenth thoracic vertebra

There is a large lytic lesion on the left side of the body that opens into a large underlying spherical cavity that encompasses approximately half of the body.  The lesion measures 16.9mm anteroposterior x 12.8mm superoinferior x 17.9mm deep.  The margins are rounded and the walls are smooth, but porotic with the loss of a normal internal trabecular pattern.  The bone surface inferior to the lesion is flattened and smooth.


Co-existing pathology

The superior and inferior surfaces have central linear depressions (Schmorl’s nodes).  The anterior margin of the superior surface has slight osteophytosis and a linear destructive lesion with pitting and porosity at its base.  The margins of the costal facets on the body are porotic/pitted.


Left rib 10

There is a large spherical space occupying lesion within the rib head, opening to the visceral surface.  The margins are sharp and the walls are smooth and thin, with perforations in the posterior wall.  The lesion measures c. 15mm mediolateral x c. 13mm superoinferior x c. 8.5mm deep.

Pathology of the Week: Sphenoidal Tumour

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This is a cranial base tumour from an individual from medieval Fishergate, York.  We are in the process of trying to get a clear diagnosis as to what type it may be and would welcome any suggestions, especially individuals with expertise in this field.  We would like to thank York Archaeological Trust for allowing us to present this material.


The primary tumour is located on the endocranial surface of the sphenoid, directly above the sphenoidal sinuses. It measures 20.9mm anteroposterior x 38.8mm medial lateral and extends above the cortical surface for c. 11-12mm at its greatest.  The tumour is made up of smoothed, regularly patterned trabeculae and is integral with the surrounding cortical bone.  Anterior to the tumour, the roof of the ethmoid and the surrounding structures have enlarged vascular channels.   Secondarily, on the ectocranial surface, the sphenoidal sinuses are exposed through a mixture of post-mortem damage and bony erosion.  This destruction reveals extensive new bone formation within the sinuses consisting of large pillars of compact bone.  These new pillars and the surrounding cortical bone have a mixture of both bone destruction and new bone deposition.

Without histological analysis a definitive diagnosis cannot be established.  This does have the appearance of being an initially benign tumour that has become aggressive.


The whole of the endocranial surface has a sharp nodular contour, with multiple peaks and ridges occurring especially on the frontal and the temporal bones.

Ballistic trauma

Description by Mike Henderson, specimen curated at The Royal College of Surgeons

RCSHC/ P 337

Right femur

A large rounded cavity is present at the midshaft of the right femur resulting from a gunshot injury.  This has resulted in a compound fracture at the middle third of the shaft.  The bullet wound penetrates the bone in an anteroposterior direction and displays smooth, rounded margins, with a larger aperture on the posterior surface.

The fractured bone is well healed although with malunion resulting in a degree of overlap and mediolateral displacement of the broken ends.  A thick plaque of new compacted bone (callus) surrounds the region of the injury and unites the overlapping edges.

The bullet was removed from the large round cavity in the middle of the bone.

The proximal head and distal end of the bone have been sawn post-mortem.

Pathology of the Week: Possible Mastoiditis


This is possibly an example of acute middle ear sepsis that resulted in mastoiditis, which perforated the petrus temporal allowing communication with the internal soft tissue structures. The individual is from St. Andrew’s Fishergate, a medieval cemetery in York   We would like to thank York Archaeological Trust for the opportunity to present these specimens.

Left temporal

An erosive lesion on the superior surface of the petrous temporal superiorly, which has sharp margins and measures c. 6.7mm x c. 2.9, penetrates to and exposes the middle ear cavity allowing for observation of the ear ossicles.   The malleus is fused to the anterosuperior roof of the middle ear cavity (red arrow).  Internally, there is pitting of the middle ear cavity with exposure of the mastoid air cells.  Further irregular lytic lesions are located in an arch at the lateral most part of the petrous temporal and the endocranial wall, some of which expose the underlying mastoid air cells.

Pathology of the Week: Klippel-Feil Syndrome

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These are selected bones from the spine of an individual from Medieval Hereford Cathedral that suffered with a congenital condition known as Klippel-Feil syndrome.  Klippel-Feil syndrome is the congenital fusion of two or more cervical vertebrae.  Clinically, Klippel-Feil syndrome is diagnosed a short neck line, low posterior hair line and limited movement of the neck (Resnick  1995) and can be associated with other hard and soft tissue anomalies.  The condition is separated into three types: Type I is mass fusion of the cervical vertebrae, Type II is the fusion of two or more cervical bodies, and Type III is Type I plus thoracic or lumbar involvement (Maclone 2001).  This individual presents with Type III Klippel-Feil syndrome with fusion within multiple cervical and upper thoracic vertebrae, other segmentation abnormalities in the cervical vertebrae and upper ribs, scoliosis, flat cranial base, and other postcranial developmental abnormalities.  The final project website will have the complete vertebral column, cranium, mandible, ossa coxae, and elements from the hands and feet for you to view!

Fused cervical vertebrae 1-3

Cervical vertebrae 1-3 are malformed and fused into a single block.  The vertebrae are fused through adjoining articular facets and bodies.  Posteriorly, there is irregular formation and fusion of the lamina and vertebral arches and spinous processes. The lamina of the 3rd cervical vertebra failed to form on the right side, while the left side is thin and irregularly shaped.  The right side of the atlas is situated more inferiorly than the left. Correspondingly, the majority of the right side of the body of the axis has failed to form. The right transverse foramen on the 3rd cervical is positioned posterior to the transverse process, instead of a normal lateral location.  Posterior to this, the inferior articular facet is not of usual shape, being more rounded and having an irregular articular contour.  The left inferior facet has joint surface contour change and is heavily pitted.  Similarly, the inferior surface of the body of the 3rd cervical is heavily pitted.  Unfortunately, the odontoid process is taphonomicaly damaged and therefore, it is unknown if it would have extended superiorly passed the foramen magnum.

Right vertebral arches of cervical vertebrae 5-7

The vertebral arches of cervical vertebrae 5-7 are fused through the laminae and inferior articular processes and then merge into a single transverse process.  Although broken post-mortem, evidence remains that the spinous processes failed to fuse to their left counterpart.  The ends of the spinous processes have slight lateral deviation.  The inferior articular facet of the fifth cervical vertebra has irregular osteophytic growth along its inferior margin and has an eburnated and heavily pitted articular surface.

Cervical vertebra 5

There is aplasia (absent due to failure to form) of the right lamina and left inferior articular facet.  The transverse foramen on the left side has stenosis (narrowing) caused by a transverse dividing layer of bone that has two openings, a small sub-circular central opening and an anterior linear opening.  Stenosis is also caused superiorly by the protrusion of a large almost horizontal articular facet.  This facet has extensive osteophytosis, surface pitting and eburnation. The right inferior facet is deformed (concave in shape) and has extensive osteophytosis, pitting and eburnation.   The body has a partial sagittal cleft with both a connecting strand internally and a bony bridge anteriorly.  There is reduction of vertebral height surrounding the cleft, which is more extensive inferiorly.  The superior surface of the body on the right side is heavily pitted and the anterior margin has extensive marginal osteophytes.

Cervical vertebra 6

There is extensive osteophytosis of the margins of the body, especially on the right uncinate process.  This right uncinate process is considerably expanded and has extensive surface pitting and eburnation.  The superior and inferior surfaces of the body have heavy pitting, with an area of coalesced pitting.  The inferior surface of the anterior tubercle on the right side has a large articular facet that is heavily pitted.  (Its adjacent articulation is not known).  The left superior articular facet is substantially smaller than what is expected in normal variation.

Cervical vertebra 7

The body is malformed with reduction in the anterior posterior width, which may represent a partial cleft.  The exact nature of the malformation of the body is obscured by post-mortem loss of the right side.  The vertebral arch is unfused and the visible left lamina and spinous process is located more lateral than of normal anatomical position.  The inferior articular facet has slight pitting.

Fused vertebral bodies of the 1st-3rd thoracic

This is the left side of a block of fused bodies of thoracic vertebrae 1-3. Although broken post-mortem, evidence remains for the reduction of body height of the 2nd thoracic anteriorly and on the right.  The height of the body of the 3rd thoracic is also reduced.

Fused vertebral arches of thoracic vertebrae 2 and 3

Due to post-mortem damage, the full exact nature of this bone is not known.  The presence of two distinct pedicles and the superoinferior elongation of the lamina on the right side suggest posterior congenital fusion of the 2nd and 3rd vertebrae.  The fusion occurs through the right lamina, inferior articular facets, spinous process, and transverse processes, with agenesis (failure of development) of the left arch and transverse process. The inferior articular facet on the left side has an area of new compact bone formation on the articular surface.

Fused right 1st and 2nd rib mass

This is what appears to be a fragment of a dysplastic fused first and second rib.  The ribs are fused through the bodies and necks. The rib heads are deformed and irregularly placed, with a mass of bone situated superiorly.  There is a large articulating facet on this superior mass that is heavily pitted.

Two fused left ribs

These two ribs are fused through the head, neck, and the body for c.16mm from the tubercle.

Fused Left 1st and 2nd rib mass

Left rib one and two are fused for c.22mm along the body and then merge to share a neck and head.  The head of rib two is bifurcated, with the inferior portion shared with rib 2 and the superior portion that extends superiorly.  The medial segment is an irregular mass of bone having multiple small articular facets (at least five separate).   The superior articular facet does not seem to articulate with any surviving elements of the trunk.  The remaining facets articulate with a lost portion of the left vertebral bodies.

Pathology of the week: TB special

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We have mutiple specimens with classic skeletal changes associated with tuberculosis in our database. Here is a sneak peak at a few of the specimens that will be available to view in 3D once the Digitised Diseases website goes live.

B0002-4: Lincoln 85 DS 4.10.  This is possible gastrointestinal tuberculosis.

Right os coxae:  There is spiculated new compact bone formation on the auricular surface, which has an irregular joint surface contour.  Superoposterior to this, there is an elliptical area of bone destruction, which has smooth margins and that interrupts a portion of the posterior iliac crest.  There is a channel of reactive new compact bone and destructive porosity between the auricular surface to the inferior margin of the destructive lesion. On the gluteal surface, there is a large, but localised, area of pitting and spiculated new compact bone.

Left os coxae: On the iliac fossa there is a large area of remodelled cortical bone destruction with peripheral new woven bone extending to the anterior superior iliac spine.  Inferior to this lesion, there is a second localised area of destructive remodelling with a large area of new woven bone inferiorly and anteriorly.  There is a large area of remodelled new compact bone extending from the auricular surface to the beginning of the superior pubic ramus.  A zone of spiculated new compact bone formation is located between the greater sciatic notch and obturator foramen lying under the gluteal musculature.

Sacrum: On the anterior surface of the vertebral bodies and the right ala (the left has taphonomic damage), there is a continuous layer of new compact bone with irregular areas of remodelled destructive changes continuing into the visible surface in the foramina.  There is a delineated area of cortical destruction leaving a scooped out appearance that has a superior border of spiculated new woven bone.  This is all in the immediate area of where the rectum is located.  On the posterior surface there is destructive remodelling and pitting along the sacral spine.  The right half of the sacral auricular surface has been destroyed, and the superior surface is disorganised with irregular new compact bone.  On the left sacral auricular surface there are four large, destructive pits/pores.

B0021: Addingham (ARC 90) 134. Rib lesions associated with TB.

Left 5th Rib: There is a fine layer of new woven bone centrally on the visceral surface of the body, which overlays thicker smooth deposits of new compact bone.

B0036: Addingham (ARC90) DS 3.22.  Pott’s Disease

1st-10th Thoracic vertebrae: There is bony fusion of the first to tenth thoracic (T1-10) vertebrae through the articular surfaces and fusion of the transverse processes inferiorly in T2-10.  The bodies of T4-6 have been completely destroyed, except for some of the posterior most surface lining the vertebral column, causing kyphosis of the column (Pott’s disease).  The inferior surface of the body of T1 is facing anteriorly. The inferior quarter of T1 is destroyed.  There is only a portion (an eighth) of the posterior body remaining for T2.  There is only an anterior wedge of T3 remaining.  The body of T7 has been compressed and there is loss of the inferior half of the right side of the anterior body.  There is further compression of T8-T10 and loss of the body of T9 on the left, giving the column a left lateral curvature (scoliosis).  The articulating rib heads to T3-T6 are fused to the vertebral bodies.  There is a depression into the inferior body of T10.  There is porotic destruction to the transverse processes of T1-T10, especially T7-T10.  Extensive pitting is observed on the spinous processes of T7-T10.

B0063: Hereford Cathedral (HE93a) 2472. Pott’s Disease

9th-12th Thoracic vertebrae (T9-12): There is bony fusion of the ninth to the twelfth thoracic (T9-T12) vertebrae anteriorly through the anterior longitudinal ligament and between T10 and T11 through the posterior longitudinal ligament, posterior body, and between the articular facets.  The body of T10 is almost completely destroyed, leaving a posterior remnant.  The body of T11 is compressed anteriorly leading to kyphosis of the vertebral column (Pott’s disease).  The joint space between the bodies of T9-T10 and T11-T12 are maintained with extensive bone destruction of the inferior bodies of T9 and T11.  There is irregular new compact bone formation on the superior bodies of T10 and T12.

B0037: Chichester (CH 86) 307.  Cranial lesions in TB.

Cranium:  There is a destructive lesion on the right parietal situated approximately in the centre of the bossing, which perforates the inner and outer tables.  The ectocranial margin is sharp and irregular.  On the endocranial surface the lesion has sharp margins, is smaller and more irregular than the external lesion, and has surrounding radial striated new woven bone.

B0039: Castleton Roman Vicus 1980. Ossification of pleura in TB.

Ossified pleura: This is an oval specimen of ossified pleura, which has jagged edges and disorganised surface on one side and a smooth surface on the other.

Potentially explosive: health and safety issues and historic radiographs

By now regular visitors will be familiar with the textured 3D laser scans and pathological descriptions we frequently put up to show the public what we are up to and what to look forward to when the project goes live later this year.

In addition to the 3D models and descriptions there will be radiographs (and CT scans). Some of the radiographs will be newly created for the project, something I have been working on for the last few months. We also will be digitising historic radiographs. At Bradford we have a scanner for digitising radiographs. It was used in the From Cemetery to Clinic project to digitise the radiography archive of leprosy patients produced by Jos Anderson almost 40 years ago.

We have a large archive of historic radiographs to digitise for Digitised Diseases. Historic radiographs provide excellent context for the discussion of health and disease. The x-ray was discovered by Wilhelm Röntgen, a professor of physics in Bavaria in 1895. It was immediately apparent that this technique would be of huge value for clinicians. In 1896 an x-ray department had been set up at the Glasgow Royal Infirmary, one of the first radiology departments in the world.

Early radiographs were recorded on glass plates with an emulsion. Just before the outbreak of WWI, the Eastman Kodak company developed a cellulose nitrate film for radiography. Cellulose nitrate was also the material used to make cinematographic film.

Essentially nitrate-based x-ray film is based on nitrocellulose (guncotton!) plasticised with camphor coated with an emulsion. It is highly flammable and potentially explosive and degrades easily, giving off toxic gases. This has obvious health and safety issues attached to it!

Luckily in the early 1920s safety film was developed for radiography. This comprised an emulsion on a cellulose acetate backing, which is much slower burning. From the 1950s to the present day polyester based films are used. These are much more stable and resist chemical and physical changes as it ages.

The video below from YouTube shows the difference between safety film (in this case 35mm cinematography film, but same principles apply) and cellulose nitrate film when it catches fire.

We were fairly sure that none of the radiographs we have were not cellulose nitrate based films. However, it is good practice to write complete a COSHH form and do a risk assessment before any digitisation work was carried out.

After looking at the older, more degraded films we were sure that none of the films were cellulose nitrate based. This is how we went about our assessment:

1. We removed the most degraded radiographic films to a fume cupboard so they could out-gas.

Fume Cupboard

2. Wearing PPE we took out the radiographs and looked at them. Degradation in some cases was very obvious.

Degrading radiograph

3. We know that from the early 1930s nitrate film and the word “nitrate” on the edge of the film. Safety film, either cellulose acetate or polyester, had the word “safety” on the edge. I found a few examples of the “safety” stamp, but no “nitrate” stamps.

Safety film stamps

4. Other radiographs had a manufacturer on. This radiograph from the 1950s is labelled “Ilford”, who make radiographic and photographic film. I was able to check that this stock was indeed safety film.


5. Looking at the dates and conditions of the radiographs in question we could rule out all of them being cellulose nitrate, as they were either too late (i.e. post 1933) or their appearance was not consistent with cellulose nitrate film. The example below shows a very wrinkled radiograph with “channeling”. It is quite brittle and has a feint vinegar smell, which is normal for old cellulose acetate radiographs.

Degraded radiograph

Some of the radiographs are extremely brittle or warped, which will present interesting conservation and digitisation decisions later on, as they are not suitable for running through the radiograph scanner. We have a number of trained conservators on the project, including the PI Dr. Andy Wilson, who will make decisions regarding how these radiographs are treated in the coming weeks.

If we had found cellulose nitrate radiographs we are fortunate to have cold storage facilities here in Bradford. We also have the very excellent National Media Museum only a short walk away, who have experts on the storage of old celluloid film – luckily we didn’t have to contact them!


Film Identification, National Park Service, US Department of the Interior

History, Science, Preservation and Treatment of Cellulose Nitrate Still Film

Managing X-ray Films as Federal Records, National Archives and Records Administration, Office of Records Services, College Park, MD (2000)

Nitrate film, National Media Museum (nd)

The Dangers of Cellulose Nitrate Film, Health and Safety Executive (2013)

Pathology of the Week

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This individual is from the medieval layers of the Gilbertine priory of St. Andrew’s Fishergate, York.  We would like to thank York Archaeological Trust for the opportunity to present these specimens. The tibia described here is part of a display at Barley Hall, about life and disease in the past.

This individual has multiple bones presenting with haematogenous osteomyelitis, including the right clavicle and humerus, sternum, and right and left tibiae and fibulae. Osteomyelitis is an infection and inflammation of the bone caused by invading pyogenic or mycobacteria, which enters the bone either through the bloodstream, from an adjacent contaminated site, and direct implantation (ie penetrating injuries).  Classic bony signs of osteomyelitis include an involucrum (a layer of new bone that encases the dead bone), a sequestrum (a segment of dead bone), and a cloaca (an opening in the involucrum that communicates with a sinus, which leads to the medullary cavity and allows for the transportation of pus to the surface) (Resnick 1995).


There is developmental delay in fusion of the sternal segments.  The manubrium is dysplastic, with reduction in superoinferior height and disorganisation of the surfaces of the costal notches, sternoclavicular joints and the jugular notch.  There is anteroposterior expansion of the manubrium and compact bone formation on the visceral surface and within the jugular notch.  Two cloacae are located on the visceral surface of the manubrium just superior to the manubriosternal joint, one centrally and the other laterally on the right side.  The lateral cloaca is surrounded by pitting and has direct communication with the anterior surface within the costal notch.

Right clavicle

There are two cloacae on the sternal end of the clavicle inferiorly, which are internally connected by sinuses that drain to the anterior and posterior surfaces.  Both cloacae are surrounded by pitting.  A possible third very small cloaca is located on the superior surface of the sternal end.  From this small hole is an open channel that runs laterally.  Alongside the channel are areas of new bone.

Right humerus

The proximal half of the shaft is greatly expanded, mainly the anterior surface.  Four cloacae are located on the anterior surface, which are connected internally through sinuses that communicate directly with the medullary cavity. The surrounding bone is heavily pitted.

External measurements of the cloacae:

Superior most- c. 12.2mm superoinferior x c.8.3mm mediolateral

Mid-lateral- c. 11.3mm superoinferior x c.6.4mm mediolateral

Mid-medial- c. 18.3mm superoinferior x c.12.6mm mediolateral

Inferior most– c. 19mm superoinferior x c.16.9mm mediolateral

Fused left os coxae and sacrum

These two bones are fused through the sacroiliac joint.  There is also irregular compact bone on the superior and anterior surface at the joint, which is porous.  The surface of the os coxae has extensive fine pitting along the superior, anterior and posterior margins of the joint.  The inferior iliac spine is largely absent due to strong ligamentous attachments that have created three deep depressions in the bone surface.

Fused right tibia and talus

The distal half of the bone is greatly expanded though proliferation of irregular compact bone (involucrum), which extends across the tibiotalar joint and covers all non-articular surfaces of the talus.  The new bone also extends onto the proximal half of the shaft but is less extensive.  There is extensive pitting across the new bone surface.  On the anteromedial surface of the distal half is a sub-circular cloaca, which measures c.6.6mm in diameter at its greatest.  A further irregularly shaped cloaca is located on the fibular notch posteriorly, c.6.9mm superoinferior x c.3.5mm anteroposterior.

Left fibula

The distal third of the shaft is expanded, with extensive compact bone (involucrum).  The whole of the distal third of the shaft has heavy fine pitting and porosity.  On the lateral surface are two large cloacae connected by an underlying sinus that contains a long, thin sequestrum.  The superior cloaca measures c. 11mm superoinferior x c.8.8mm mediolateral and the inferior cloaca measures c. 9.4mm superoinferior x c.5.1mm mediolateral.  There is a further shallow lytic lesion on the lateral surface superior to the two cloacae measuring c. 3-5mm in diameter.

Resnick, D. 1995. Diagnosis of Bone and Joint Disorders. W.B. Sunders, Philadelphia.