Juvenile Rheumatoid Arthritis : Wheeless' Textbook of Orthopaedics

Discussion

JRA is a persistent non infectious arthritis lasting more than 6 wks to 3 months after other possible etiologies have bee ruled out;
most common chronic childhood rheumatoid dz;
affects girls more than boys;
synovial proliferation leads to joint destruction (chondrolysis) & soft tissue destruction;
severe joint destruction is seen in only 5% of patients;
differential diagnosis:
in order to confirm the diagnosis, one of the following is required:
- rash
- presence of RF
- iridocyclitis
- C-spine dz
- pericarditis
- tenosynovitis
- intermittent fever
- AM stiffness;
sub-types
- pauciarticular: 4 or less joints in > 6 mo.
- polyarticular: 5 or more joints in > 6 mo.
- systemic JRA: begins w/ high spiking fevers ( > 39.3) & rash;

synovial fluid exam:
antinuclear antibody test:
- positive antinuclear antibody test is diagnostic of JRA;
- most often positive in younger females with oligoarticular disease and has increased risk for anterior uveitis

atlantoaxial instability makes intubation potentially hazardous (consider lateral flexion and extension radiographs);
children w/ seronegative JRA tend to have stiff necks 2nd to spontaneous fusion of the posterior fascets;
reference: Changes in the cervical spine in juvenile rheumatoid arthritis.

flexion contractures (hip and knee flexed, & ankle dorsiflexed), subluxations & other deformities (hip protrusio, valgus knees, & equinovarus feet);
growth deformities of the limbs:
- JRA may either cause lower extremity overgrowth (in patients less than age 9) or may lead to physeal arrest (in patients older than age 9);
- generally, when the disease develops before age 9, will have overgrowth of involved extremity, but overgrowth will not exceeded 3.0 cm;
  - major discrepancy developed within the first 3-4 yrs and will then either increase very slowly thereafter, will remain level, or will decrease;
- reference: Leg-length discrepancies in monoarticular and pauciarticular juvenile rheumatoid arthritis.
hip
- references:
knee
- this joint is affected most often in JRA (66%) followed by ankle in 25%;
- reference: Total hip and knee arthroplasty in juvenile rheumatoid arthritis.
foot
- polyarticular JRA, simultaneous involvement of ankle & subtalar joints & remainder of the joints in the foot is common;
- ankle contracts into equinus (talipes equinus);
- subtalar joint may develop a varus or valgus deformity;

includes night splinting, salicylates, and rarely, synovectomy (for chronic swelling refractory to medical management);
arthrodesis and arthroplasty may be required for severe JRA:
- note: mortality rate for JRA pts undergoing arthroplasty is approx 18%, w/ death occurring before the third decade