【One case per day】Ankylosing spondylitis

Result: Ankylosing spondylitis

The characteristic x-ray of ankylosing spondylitis is that the calcified ossification of the paravertebral ligaments is a bamboo-like change
.

Early x-rays show sacroiliitis, and lesions generally begin in the middle and lower part of the sacroiliac joint and are bilateral
.
Invasion of the iliac side begins to occur more and then the sacrum side
.
Spotty or lumpy bony sides are seen
.
It can then invade the entire joint, with serrated edges, bone hardening under the cartilage, bone hyperplasia, and narrowing
of the joint space.
Finally, the joint space disappears and osseous rigidity
occurs.

1 Pathology:

Ankylosing spondylitis may be associated with
bacterial, viral infections, endocrine disorders, moisture, involvement, and malnutrition.
Pathologic changes are similar to those of rheumatoid arthritis and are dominated
by nonspecific synovitis and cellulose deposition.
Early synovial hyperemia, edema, soft tissue swelling
.
Subsequently, synovial granulation tissue hyperplasia, joint cartilage and subchondral bone erosion and destruction
.
Compared with rheumatoid arthritis, its exudation is lighter and proliferative changes are significant
.
Beginning in the sacroiliac joint, early destruction, space narrowing and subchondral osteosclerosis, upward invasion of the lumbar spine, thoracic spine, cervical spine is rare, ligaments including anterior longitudinal ligament, flavum ligament, joints and tendons are prone to calcification and ossification
.
The disease can be accompanied by chest, rib, clavicle hypertrophy, rheumatoid arthritis, and some enteritis
.

2 Clinical:

Ankylosing spondylitis is more common in men under 30 years of age and less often in women, with a male-to-female ratio of 5:1
.
The onset is insidious, and at first it is usually dull pain in the buttocks, sacroiliac joints, or the back of the thighs, which is difficult to locate
.
Low back pain and discomfort are the most common symptoms of this disease, which worsen in the morning (morning stiffness) and are relieved
after activity.
Spinal involvement limits mobility, and costal joint involvement limits thoracic mobility
.
During the active phase, pain and tenderness in the sacroiliac joint, pubic symphysis, spinous process, iliac crest, greater trochanter, ischial tuberosity, and calcaneus
.
More than half develop peripheral joint pain and dysfunction, affecting the hip and shoulder joints
.
Under the age of 14, it is called juvenile ankylosing spondylitis, which is more likely to invade peripheral joints and can initially appear as peripheral joints
.
Iritis
occurs in 1/4.
A few invade cardiovascular, lung, kidney, etc
.

3 Laboratory tests:

The synovial membrane is generally pathologically examined as nonspecific inflammation
.
Immunohistochemical analysis, tonic acute phase, some may have elevated C-reactive protein, accelerated ESR, 90% HLA-B27(+), (4%-8% of normal people are positive), rheumatism factor is mostly negative, spondylitis plasma cell infiltration is dominated by IgG and IgA (rheumatoid arthritis is dominated by IgM).

Image representation:

(1) X-ray examination

1.
Early manifestations: universal osteoporosis, not easy to diagnose, and poor prognosis

2.
Sacroiliitis:

Almost 100% of the bilateral sacroiliac joints are violated, and they are symmetrical, which is the main basis for diagnosing the disease, and 11.
4% can also start on one side, and then occur on the opposite side within months or a year, starting from the lower 2/3, bone destruction is mainly on the iliac side.
At first, the iliac articular surface is blurred, and later eroded and destroyed, it is rat bite-like, the edge hyperplasia and hyperplasia, and the joint space is "pseudo-widened".
Then the joint space narrows.
Finally, it is manifested as bony rigidity and sclerosis disappears.
The diagnostic criteria formulated in New York in 1996 divide sacroiliitis into five grades, which are widely accepted worldwide.
The grades are as follows: grade 0: normal; grade I: suspicious abnormality; Grade II: mild abnormality, localized erosion and hardening can be seen, but there is no change in the joint space; Grade III: obvious abnormality, moderate or severe sacroiliitis, with one or more of the following: erosion, sclerosis, widening or narrowing of the joint space, partial rigidity; Grade IV: severe abnormalities, complete osteorigidity
of the joint.

3.
Spinal changes:

After the onset of sacroiliitis, it gradually ascends to the spine, affecting about 74%.

Lesions begin to invade the upper and lower corners of the anterior edge of the vertebral body (Romanus lesions) and bony process joints
.
When the Romanus lesion is aggravated, the concave surface in front of the vertebral body becomes straight or even convex, forming a "square vertebrae"
.
Inflammation causes ossification of the fibrous ring and the deep layers of the anterior longitudinal ligament, forming ligament osteophytes parallel to the spine, giving the spine a bamboo appearance, that is, a "bamboo-like spine"
.
In the late stage, the bony process articular capsule, ligament flavum, interspines, and supraspinous ligament can be ossified; Extensive ossification makes the spine rigid and less intense, and minor trauma can lead to fractures
.
Fractures are not easy to heal and form "pseudo-joints", and at the "pseudo-joints" or segments of the ankylosing spine that can still move, irregular erosion and hardening of adjacent vertebral endplates due to force changes, that is, Anderson lesions, are easily misdiagnosed as tuberculosis, purulent osteomyelitis or metastases
.
Alantoaxial erosion occurs more anterior and dorsal to the ulnar process, and atlantoaxial subluxation is less
common than rheumatoid arthritis.

4.
Adhesion disease:

The attachment parts of tendons, ligaments and joint capsules and bones may have ossification perpendicular to the bone surface, coarse beard-shaped, or bone erosion, that is, adhesion disease, accounting for 10.
7%
of patients with ankylosing spondylitis.
The ischial tuberosity, greater trochanter of the femur, iliac crest, spinous process of the spine, and calcaneal tubercle are common sites
.

5.
Peripheral joint changes:

The hip joint is the most commonly affected peripheral joint, accounting for 37.
9%
of ankylosing spondylitis.
JAS can also first affect the hip (about 76% of eventual involvement) or knee joints, followed by the sacroiliac joint and spine
.
Hip arthritis is mostly symmetrical, manifested by narrowing of the joint space, erosion of the articular surface, subarticular capsule degeneration, reactive osteosclerosis, osteophytes and osseous rigidity
at the outer edge of the articular surface of the acetabulum and femoral head.
There are few x-ray changes
in other peripheral joints.

(2) CT examination:

Primary sacroiliac joint scan eliminates overlapping interference, shows joint contour and articular surface erosion more clearly than plain radiograph, and can detect erosion foci
early.
Sacroiliac joint sacrum side erosion destruction, hyperplasia and sclerosis
.

Comments:

Ankylosing spondylitis is a chronic nonspecific inflammation of unknown cause, characterized by
major violations of the axial bone (joint), sacroiliac joint involvement, and attachment disease.
The disease was once named rheumatoid arthritis, and ankylosing spondylitis was considered a type of rheumatoid arthritis or called the central type
.
However, studies in recent years have shown that there are obvious differences
in clinical manifestations, genetic factors, immune responses, pathological changes, and imaging.