Juvenile Idiopathic Arthritis
Types of Juvenile Idiopathic Arthritis
Systemic Arthritis
This type makes up 4-17% of cases of JIA. [1]
It is initially characterized by a fever that spikes to over 39 degrees Celsius 1-2 times daily [2]. While feverous, the child will likely experience a bright pink rash that usually becomes widespread across the limbs and torso. [2] Arthritic symptoms are usually present in the wrists, ankles, and knees. Muscles in the jaw can also become sore and stiff. This type of arthritis can also cause swelling of internal organs. [2]
Polyarthritis
This type makes up 11-28% of cases of JIA. [1]
This type of arthritis affects 5 or more joints. [2] It may impair also small joint functioning, such as in the fingers and toes.
Oligoarthritis
This type makes up 27-56% of cases of JIA. [1]
It affects 4 or fewer joints, particularly in the lower half of the body. [2] The knee joints are involved in 30-50% cases, and ankles are also often affected. [1] Children with Oligoarthritis also have a higher rate of uveitis, which is the swelling of the eye, that leads to eye pain and blurred vision. [2]
Enthesitis-Related Arthritis
This type makes up 3-11% of cases of JIA. [1]
This type primarily affects males over the age of 6. [1] The tendons connected to the bone become painful and stiffen, especially in the lower limbs. This occurs particularly where the calf muscles combine with the Achilles tendon. [1] This arthritis can cause back pain, hip pain, and inflammation in the lower spine. This type of arthritis may involve uveitis. [2]
Psoriatic Arthritis
This type makes up 2-11% of cases of JIA. [1]
In this type of arthritis, a rash is usually present along with typical arthritic symptoms. Other signs include finger swelling and nail pitting. [1]
Undifferentiated Arthritis
This type makes up 11-21% of cases of JIA. [1]
Cases that do not fit into any of the above categories or that fit in more than one
Glossary
Torso: The shoulders down to the hips of the body
Tendon: Tissue attaching muscle to bone
Achilles Tendon: Tissue connecting the calf muscles to the heel bone
Uveitis: Swelling of the middle layer of the eye
Nail Pitting: Small dents in the nails
References
1. Angelo Ravelli, and Alberto Martini, "Seminar: Juvenile Idiopathic Arthritis," The Lancet 369, no. 9563 (2007): 767-778.
2. Gabriella Giancane, Alessandro Consolaro, Stefano Lanni, Sergio Davi, Benedetta Schiappapietra, and Angelo Ravelli, "Juvenile Idiopathic Arthritis: Diagnosis and Treatment,"Rheumatology and Therapy 3, no. 2 (2016): 187-207.