The affectation of the vertebral bodies (alteration in their morphology,
size or mineralization) is usually due to sistemic diseases.
However,
arthropathies usually alter the disc space and the interapophyseal joints.
Alteration of the vertebral body:
- Paget's disease,
which typically produces an increase in gross size with disordered internal structure due to an alteration between bone production and resorption Fig. 1 . Paget's disease can show the typical appearance of“vertebra in frame”,
where the whole cortex is more dense than the trabecular bone of the vertebral body.
-Eosinophilic grauloma,
which usually produces a crushing of the vertebral body with preservation of the disc and the posterior elements.
-Lymphoma usually causes sclerosis of the vertebral body.This finding can also be produced by blastic metastases such as those produced by prostate cancer.
-Hyperparathyroidism typically produces the image of vertebrae in a Rugby shirt (Rugger-jersey spine).
It is characterized by sclerotic bands in the upper third and in the lower third of the vertebral body,
but is important to know that the bands of sclerosis are poorly defined,
with gradual transition of the margins sclerotics towards the osteopenia area Fig. 2
-The sign of the "sandwich" vertebra is traditionally observed in osteopetrosis type II (Albers-Schonberg disease).
It has an autosomal dominantinheritance and is characterized by osteosclerosis secondary to a defect of bone resorption due to a aberration in osteoclasts.
The sandwich vertebra is not pathognomonic of this disease however,
and it can also be observed in the course of an exogenous or endogenoushypercortisolism.
The image of the vertebra ``in a sandwich´´ consists of the upper and lower vertebral margins being radiodensewith a well defined sclerosis,
with well-defined borders unlike the rugby shirt image caused by hyperparathyroidism.
-Osteosopicnosis is a sclerotic bone dysplasia of unknown etiology,
of autosomal dominant transmission and benign course,
which is characterized by increase in bone density,
predominantly in the axial skeleton,
which can also give an image of a sandwich vertebra.
-H-shaped vertebrae Fig. 3 . Is a characteristic finding of sharply delimited central endplate depression, classically seen in approximately 10% of patients with sickle-cell anaemia, and results from microvascular endplate infarction.It may occasionally be seen with other conditions such as Gaucher disease.
Alteration of the interapophyseal joints:
The most common pathology at this level is arthrosis Fig. 4 ,
which alters the joint space,
causing the formation of osteophytes and sclerosis by reparative bone formation.
Other causes are inflammatory arthropathies,
which will cause erosion +/- final ankylosis.
Alteration of the disc space Fig. 5 Fig. 6 :
The most frequent cause is degenerative.
Other causes are inflammatory arthropathies.
The radiographic signs of disc space involvement are:
-Air density
-Decreased space
-Calcifications
In the following section,
different types of ostehophytes will be discussed.
There are 4 different types of osteophytes:
1-Syndesmophytes
2- Marginal osteophytes
3- Non-marginal osteophytes
4- Paraespinal osteophytes
Syndesmophytes
They consist of vertical ossification bridges that joins two adjacent vertebral bodies Fig. 7 thatrepresent the ossification of Sharpey fibers.It is observed in contiguity with the vertebral bodies because the Sharpey fibers are introduced into the thickness of the vertebral body.
The deep layers of the longitudinal ligaments can also be ossified during the formation process of this osteophyte.The finding of this osteophyte is a diagnostic key in ankylosing spondylitis but can also appear in psoriatic,
reactive arthropathy and secondary to inflammatory bowel disease.
Marginal osteophytes
They are horizontal bone extensions of the vertebral plate.
Theyconstitutes an integral part of the vertebral body,
since it has a medullar space contiguous with the medullary space of the vertebral body and a cortex contiguous with the cortex of the vertebral plate Fig. 8 Fig. 9 .
Those of small size are more often associated with degenerative disc disease and spondylosis deformans (osteoarthritis).The larger ones can incurvate and join those of the adjacent vertebral body,
giving a vertical path that forms a bridge.
This is most often post-traumatic,
but may appear in other pathologies,
along with other types of osteophytes that help us diagnose the underlying process.
Non-marginal osteophytes
They are horizontal prolongations of the vertebral body that grow away (2-3mm) from the plane of the vertebral plate Fig. 10 .It is believed that they indicate the existence of instability in the spine,
which is secondary to tensile forces.
They are also part of the vertebral body,
with it scortex and medullar space connecting with those of the vertebral body.They extend first in horizontal direction and then verticaly.
They can also bend and join to that of an adjacent vertebral body giving a vertical path with bridge formation.
Those of small size are associated with degenerative disc disease and deforming spondylosis.
The larger ones (sometimes called non-marginal syndesmophytes) are associated with psoriatic and reactive arthropathy.
Paraespinal osteophytes
They are ossifications of the soft tissues that surround the vertebral body.
They are not part of the vertebral body.
Radiographicallyit is frequent that theymanifest as ossifications of longitudinal ligamenta.
A radiolucent line separating this ossification from the cortex of the vertebral body can be observed.
Its most frequent manifestation is idiopathic diffuse skeletal hyperostosis (Forestier-Rotes Querol disease) Fig. 11 .
Below,some examples of the different types of osteophytes described in various diseases are provided
Primary and secondary degenerative disc disease
It consists of degenerative affectation of the disc space Fig. 12 , which can not be called osteoarthritis because the intervertebral disc has no synovium.It is the most frequent radiographic finding in patients with back pain.It is due to the loss of elasticity of the nucleus pulposus,
which causes loss of height of the intervertebral disc and therefore loss of disc space height,
which is the most frequent radiographic sign.
An absolute sign is calcification and or the vacuum phenomenon in the disc space Fig. 6 .We can also find an intervertebral osteochondrosis,
which is the disease of the nucleus pulposus,
which is observed in elderly people or secondary to trauma in young people.
This produces loss of disc space height,
vacuum phenomenom,
disc calcifications Fig. 5 and subchondral bone sclerosis in adjacent vertebral bodies with formation in addition to marginal and non-marginal osteophytes.In summary,
in the primary and secondary degenerative disc diseases,
the bodies in contact with the degenerated disc developsmall marginal and / or non-marginal osteophytes,
subchondral sclerosis and depending on whether these findings are observed in one rachis level alone or in multiple,
there are different causes:
a) In one rachis level exclusively:
-Natural aging
-Premature aging secondary to trauma in young people.
b) At multiple levels without structural anomaly: there may be an underlying arthropathy.
Most often,
it is chondrocalcinosis,
in whichcalcifications are usually seen in soft juxtadiscal tissues,
but it can also be secondary to:
-Acromegaly,
in whichin addition to degenerative disc disease increased anteroposterior diameter of the vertebral bodies can be seen.
-Ochronosis,
in which disc degeneration is observed at all levels of the spine.
This is due to the deposit in the intervertebral discs of a homogentisic acid polymer due to a lack of homogentisic oxidase.
Patients with this disease usually present skin pigmentation and associated arthropathy.
The involvement of the spine is of lumbar predominance with progressive ascending affectation.
In the final stages some patients present ankylosis and a differential diagnosis with ankylosing spondylitis needs to be made.
Extreme degenerative disc disease: neuropathic column.
Years ago,it was observed almost exclusively in the tabesdorsalis.
Now it is more observed in uncontrolled diabetes.
The following radiographic changes occur:
-Disolution of the disc space
-Folding of a vertebral body over another
-Reformative bone formation in the entire vertebral body
-Mass formation of osteophytes
-Bone fragmentation
Deforming spondylosis
In this entity,marginal and non-marginal osteophytes surrounding a disc of normal height are observed.
Sharpey fiber degeneration occurs,
which facilitates disk movement above all anterior,
which causes the formation of marginal osteophytes and traction of the anterior common vertebral ligament causing traction osteophytes Fig. 13 .
Arthrosis in the interapophyseal joints
It most frequently affects the lower cervical and lower lumbar spine. Fig. 5 Joint space decrease,
subchondral bone sclerosis is observed,
and osteophytes andsubchondral bone cystsmay appear.
If cartilage loss is severe,
it maycause lumbar grade I spondylolisthesis or cervical subluxation.
Arthrosis in the sacroiliac joints
Greater loss of cartilage occurs in the upper and lower third of the sacroiliac synovial joints.
Subchondral bone sclerosis and osteophytes are also observed superiorly and inferiorly.
Bony iliac-sacral bridges can be observed,
in whose case differential diagnosis with ankylosis due to inflammatory arthropathy must be made.
Ankylosing spondylitis
In conventionalradiographies,
the first thing that can be observed is quadrature of the vertebral bodies secondary to enthesitis.
Fig. 14 .If the disease progresses,
syndesmophytes can be observed.
The affectation of the spine follows an ascending path and finally it can cause the radiological image of bamboo spine Fig. 15 and Fig. 16 ,
with variable interapophyseal ankylosis.The disc spaces are preserved but calcifications can be seen Fig. 17 .In this entity,
the analysis of the sacroiliac joints is important to make a correct differential diagnosis with other entities.
The involvement of the sacroiliac joints in ankylosing spondylitis is typically bilateral and symmetricFig. 18,with erosions and subchondral sclerosis,
complete fusion of the joint occurs in advanced stages.
Intestinal inflammatory diseases
(Crohn's disease,
ulcerative colitis,
intestinal bypass procedures and Wipple's disease) Fig. 19 .10% of these diseases affect the sacroiliac joints and cause spondylitis.The involvement of the sacroiliac joints is bilateral and symmetrical,
with syndesmophytes and vertebral quadrature.
For a correct diagnosis,
it is necessary to correlate the radiographic findings with the results of complementary tests and to analyze the clinic of the patient as a whole.
Reactive and psoriatic arthritis
The affectation of the rachis that produces these diseases is asymmetric and exuberant Fig. 20 .It is frequent to observe non-marginal osteophytes forming asymmetric bridges Fig. 21 .There may or may not be syndesmophytes.The affectation can be unilateral or bilateral,
but the distribution is patched.Disk spaces are usually respected.Spinal involvement is more frequent in psoriatic than in reactive.To make the differential diagnosis with ankylosing spondylitis,
it is important to remember that reactive and psoriatic arthritis can affect the sacroiliac asymmetrically and that spinal and sacroiliac syndesmophytes are usually more exuberant and coarse in these than in ankylosing spondylitis.
Forestier-Rotes Querol disease Fig. 11 .
It produces paraspinalostephytes.
It is not an artopathy,
and therefore,
it does not affect the cartilage-articular bone.
It is a diathesis that forms bone.First,
ligaments and tendons are affected in the areas of insertion.,
and in the spine,the longitudinal ligaments ossify.
It tends to affect the thoracic vertebrae causing excessive and undulated ossification anterior to the vertebral bodies.
It does not ossify Sharpey fibers.
It is characteristic to see a radiolucence in `` Y´´ or `` T´´ between the ligament and the vertebral plate.
It is diagnosed when four adjacent vertebral bodies are observed.In 10% of cases,
the ossification is fine and raises the differential diagnosis with ankylosing spondylitis.
Occasionally,
a differential diagnosis can be made with some arthropathy,
in whose case,
it is useful to observe the sacroiliac joints,
which are normal in this disease.