Joint deformity

Introduction Although the joint deformity is a "typical product" of rheumatoid arthritis, it is not the exclusive operation of rheumatoid arthritis. Joint deformities can be caused by a variety of causes, many diseases, which may be caused by diseases of the tissues surrounding the joints, or by intra-articular lesions. Common types of joint deformities are as follows: (1) button flower malformation: proximal interphalangeal joint flexion, distal knuckle overextension. (2) Telescope malformation: due to the large absorption of the metacarpal bone end, the fingers are obviously shortened, the finger skin has obvious organ-like wrinkles, the finger joints are slack and unstable, and there is abnormal lateral activity. The affected finger can be stretched or shortened, like a telescope. (3) clubbing deformity: refers to the incomplete extension of the flexor tendon, which causes the tendon to prolong and form the flexion deformity of the distal interphalangeal joint. (4) "goose neck" deformity: metacarpophalangeal joint flexion, proximal interphalangeal joint overextension, distal interphalangeal joint flexion, looks like a goose's neck from the side. (5) ulnar deformity: due to the weakness of soft tissue relaxation except the thumb, the distal ends of the other limbs are centered on the metacarpophalangeal joint, and are skewed toward the side of the little finger, resulting in a "Z" shape.

Cause

The maintenance of normal joint structure and function depends on the joint surface, joint capsule, muscles around the joints and ligaments. The pathological changes of rheumatoid arthritis mainly in joint synovial membrane, synovial inflammation, hyperplasia, inflammatory substances released into the joint cavity to destroy the articular cartilage, and the proliferating inflammatory tissue invades the bone edge of the joint. It blocks the contact of cartilage and joint fluid and affects its nutrition. On the other hand, certain hydrolases are produced, causing damage to the collagen matrix in articular cartilage, subchondral bone, ligament and tendon, causing damage to the articular surface, muscle atrophy around the joint, and elongation of the ligament to fracture. In this way, the joint surface and the joint muscles and ligaments of the joint mechanism and function are maintained, resulting in joint deformity and limited activity. In the late stage of rheumatoid arthritis, fibrosis and even ossification between the two articular surfaces, the joints are stiff and the function is lost.

an examination

Related inspection

Trendelenberg's joint examination of the general examination of the bones and joints of the extremities, bone and joints and soft tissue CT examination

In patients with rheumatoid arthritis, swelling, pain, morning stiffness, and limited mobility of the proximal interphalangeal joint and metacarpophalangeal joint begin to occur. With the development of the disease, the hand-held device is weak, the grip strength is reduced and gradually increased, and there will be different degrees of deformity in the late stage.

The deformity of rheumatoid foot refers to the subluxation of the ankle joint, the subluxation of the big toe joint and the hallux valgus, and the deviation to the temporal side and the metatarsal joint to the temporal side, which can cause severe pain and difficulty in walking.

Differential diagnosis

Joint deformities of several common joint diseases can be seen in:

(1) Rheumatoid arthritis

In the early stage, the synovial exudative lesions were mainly caused by the development of the synovial exudative lesions, and the synovial exudative changes became proliferative and granulomatous lesions, and the range of joint activity was reduced. Later, due to synovial granuloma erosion To the osteochondral, causing joint displacement and dislocation, coupled with tissue destruction and scar formation around the joints such as ligaments and joint capsules; thus deforming the joints.

(2) psoriatic arthritis

The disease is most likely to involve the distal interphalangeal joint. The soft tissue around the joint can be seen in the early stage. Later, with the destruction of the articular cartilage, the joint space becomes narrow, and the late affected joints are subluxated or stiff, and the distal interphalangeal joint can appear. Flexion deformity.

(3) ankylosing spondylitis

Due to inflammatory changes in the ligament and joint capsule attachment, granulation tissue proliferates in the ligament, periosteum, trabecular bone, etc., and fibrosis gradually occurs, and there is a significant ossification tendency near the joints and joints, and finally the fibrous rigidity of the joint occurs. And skeletal rigidity. The inflammatory changes of the vertebrae are the same as the joints. The inflammation of the cartilage endplates and the intervertebral disc edge of the vertebrae can cause local ossification; the anterior and lateral outer fibers of the intervertebral disc annulus form ligaments, which can be extended longitudinally and finally become two directly adjacent vertebral The bone bridge structure of the body; osteoporosis of the vertebrae and muscle atrophy cause thoracic kyphosis.

(4) Osteoarthritis

It is most common in the distal interphalangeal joints to thicken, local "bone spur" formation and nodular changes. The joint is deformed due to a nodular change, and the finger end can be deflected to one side.

(5) Gout

Due to the increase of uric acid in the blood, tophi can form, when the disease progresses to chronic arthritis, due to the continuous deposition of tophi, joint tissue destruction, fiber proliferation, bone hyperplasia, resulting in joint deformity.

(6) False gout

When the acute recurrent episode of the disease enters the chronic phase, the synovial membrane thickens and causes the joint to be slightly flexed and contracted to become deformed.

(7) Tuberculous arthritis

It is a specific inflammation caused by Mycobacterium tuberculosis invading joint tissues. Joint deformity can be seen in the late stage.

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