Unexplained joint swelling in children
Beware --- "Juvenile idiopathic arthritis"
Salin
The 6-year-old girl, Niu, whose knees have been swollen for more than 2 months, has not sprained, fallen, or smashed, and has not improved after resting, her mother took her to the pediatric orthopedic clinic for examination, telling the doctor that the child had knee swelling for unknown reasons and could not straighten it recently (Figure 1). After a series of tests, the doctor told her mother that her disease was diagnosed with a condition called "juvenile idiopathic arthritis". Today, let's talk about what "juvenile idiopathic arthritis" is.
Figure 1: Photograph of the appearance of a swollen knee joint
Figure 2: Arthrocentesis showed pale yellow joint exudate
1. What is "juvenile idiopathic arthritis"?
Juvenile idiopathic arthritis is a common connective tissue disease in childhood, characterized by chronic synovitis, which can be accompanied by systemic multisystem damage, and is also an important cause of childhood disability and blindness.
The International Union of Rheumatology Pediatric Standing Committee Expert Group (IPEU) defined monoarthritis or polyarthritis with unknown causes lasting 6 weeks or more in childhood, excluding other known causes, as juvenile idiopathic arthritis (JIA).
2. What are the main clinical manifestations of idiopathic arthritis in children?
The JIA classification of the International Anti-Rheumatology Alliance includes systemic type, oligoarticular type, polyarticular type, psoriatic arthritis, undifferentiated arthritis, etc.
(1) Oligoarticular JIA
Oligoarticular type is the most common subtype of JIA, accounting for about 27%~56% of JIA, mostly occurring in female children (female: male 4:1), peak age of onset <6 years old. Oligoarticular JIA has 1~4 joints involved in the first 6 months of onset. If the duration of the disease is greater than 6 months, the number of joint involvement is greater than 4, which is defined as extended oligoarticular JIA; There are 4 joints involved in the course of the disease ≤, defined as persistent oligoarticular JIA.
Large joints such as knees, ankles, elbows, or wrists are common sites and are often asymmetrical. Wrist involvement indicates progression to an extended or polyarticular form and relatively difficult to control. Shoulder involvement is rare. Cervical spinous process involvement may present as torticollis.
Most children complain of joint pain and morning stiffness. 25% of children have no joint pain and only joint swelling. Although arthritis recurs, it is rarely disabling.
(2) Polyarticular JIA
Polyarticular type is also a more common subtype of JIA, accounting for about 18%~30% of JIA. The onset of this type is insidious and there are ≥5 affected joints, which are symmetrical or asymmetrically distributed, and can involve both large and small joints. Involvement of small joints such as metacarpophalangeal/metatarsophalangeal joints, proximal interphalangeal joints, and interphalangeal joints is common. The cervical spine and temporomandibular joints are often easily involved.
The initial disease may be accompanied by low-grade fever, and the febrile type is usually irregular. Polyarticular types are divided into two categories: rheumatoid factor (RF) positive and negative. Children with the RF-positive type may develop Felty syndrome (splenomegaly with leukopenia). Rheumatoid nodules occur in about 10% of children, commonly around the elbow and knee.
This type of joint has severe symptoms, and if not treated in time, more than half of them will cause joint rigidity and deformation, which will affect joint function.
(3) Extra-articular manifestations
a. Iridocyclitis: The common extraarticular manifestations of oligoarticular and polyarticular JIA are iridocyclitis, also known as chronic uveitis. About 20%~30% of children develop chronic iridocyclitis, resulting in visual impairment and even blindness. Some children present with eye redness, photophobia, tearing and other discomfort, but some children do not show eye discomfort, and are only found in routine slit lamp examination. Uveitis is common in children with oligoarticular and polyarticular JIA who are positive for antinuclear antibodies.
b. Pulmonary lesions: polyarticular JIA can present with pulmonary lesions, the most common of which is interstitial pneumonia, and in severe cases, interstitial fibrosis, pleurisy, rheumatoid pulmonary nodules, bronchiolitis obliterans, pulmonary vascular disease, and pulmonary hypertension.
c. Hepatosplenic and lymphadenopathy: severe oligoarticular and polyarticular JIA can cause hepatospleen and lymphadenopathy, which can improve with treatment.
3. What tests can be done for diagnosis?
(1) Blood immunological examination: rheumatoid factor (RF), antinuclear antibody (ANA), anti-cyclic citrullinated peptide antibody (ACCP), white blood cell count (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), etc., but none of the examinations have diagnostic value, and the above examinations are only indicators for judging disease activity and differential diagnosis.
(2) Imaging examination: X-ray examination, early can show soft tissue swelling, osteoporosis, etc., in the late stage can see joint surface destruction, joint deformity, etc.
Magnetic resonance imaging (MRI) can evaluate osteoarticular lesions earlier and more comprehensively, including intra-articular effusion, synovial membrane, cartilage, etc., which is a sensitive means for early JIA diagnosis.
Ultrasonography can safely and accurately display joint exudate and synovial thickening, which is more convenient.
4. What diseases need to be identified?
JIA is a class of exclusionary disorders in which other possible conditions are excluded at diagnosis:
(1) Other connective tissue diseases: such as arthritis caused by systemic lupus erythematosus and juvenile dermatomyositis, should be asked whether there are rashes and muscle weakness in the medical history, combined with autoantibodies, organ related auxiliary examinations to clarify.
(2) Infectious arthritis: such as septic arthritis, tuberculous arthritis, brucellosis, etc., combined with clinical manifestations and etiological test results for identification.
(3) Malignant diseases of the blood system: such as acute leukemia, lymphoma, malignant histiocytosis, etc., differential diagnosis is carried out through imaging examination and biopsy such as bone marrow cytology, lymph node and local lesion biopsy.
(4) Others: such as ankylosing spondylitis, pigmentation villous nodular synovitis, arteriovenous malformations, coagulation disorders (such as hemophilia) and severe trauma.
5. Treatment
(1) General treatment
Ensure proper rest and adequate nutrition for the child. Encourage your child to participate in appropriate exercise and live as healthy as possible.
Proper range of motion training and muscle strength training using physical therapy and other measures can prevent joint rigidity and soft tissue contractures and muscle atrophy.
(2) Drug treatment
Drugs include nonsteroidal anti-inflammatory drugs (NSAIDs), immunosuppressants, glucocorticoids, condition-modifying antirheumatic drugs (DMARDs), calcium, biologics, and small molecule targeted drugs. Consultation with an experienced paediatric immunorheumatologist should be consulted for specific medications.
(3) Surgical treatment
Conventional medical treatment sometimes fails to prevent the destruction of joint structures, which may cause osteoarthritis and joint deformities in the long term. Arthroscopic surgery has the advantages of safety and minimally invasive, applicable joints include shoulder, wrist, hip, knee, ankle joint, etc., by obtaining intra-articular lesion tissue, in addition to clarifying pathological diagnosis, arthroscopic synovial resection helps to relieve pain and restore joint function, and it has been widely reported that it has a good effect in the treatment of adult rheumatoid arthritis. Compared to traditional incisional surgery, arthroscopic surgery has little damage to the joint capsule and ligaments and can restore mobility immediately after surgery. Arthroscopic synovial resection has been shown to yield satisfactory results with early intervention in children with JIA with oligoarticular persistent uniarticular involvement. (Figure 3-5)
Figure 3: Knee arthroscopic surgery during surgery
Figure 4: Arthroscopic use of radiofrequency knife to clean the diseased synovial tissue