US measurements of distal femoral cartilage thickness are highly correlated to MRI measurements. The intercondylar notch of the distal femoral cartilage may be the best anatomical point for cartilage thickness measurements of the knee. US is a reliant and nonexpensive, non-invasive modality for visualization of childhood femoral cartilage.

Children with JIA have reduced cartilage thickness compared with children who do not have JIA, and children with polyarticular and systemic JIA have thinner cartilage than children with oligoarticular JIA.

BackgroundBoneXpert is an automated method to calculate bone maturation and bone health index (BHI) in children with juvenile idiopathic arthritis (JIA). Cartilage thickness can also be seen as an indicator for bone health and arthritis damage. The objective of this study was to evaluate the relation between cartilage thickness, bone maturation and bone health in patients with JIA.MethodsPatients with JIA diagnosed according ILAR criteria included in a previous ultrasonography (US) study were eligible if hand radiographs were taken at the same time as the US examination. Of the 95 patients 67 met the inclusion criteria.ResultsDecreased cartilage thickness was seen in 27% of the examined joints. Decreased BHI was seen in half of the JIA patient, and delayed bone maturation was seen in 33% of patients. A combination of decreased BHI and bone age was seen in 1 out of 5 JIA patients. Decreased cartilage thickness in the knee, wrist and MCP joint was negatively correlated with delayed bone maturation but not with bone health index.ConclusionDelayed bone maturation and decreased BHI were not related to a thinner cartilage, but a thicker cartilage. No relation with JADAS 10 was found. The rheumatologist should remain aware of delayed bone maturation and BHI in JIA patients with cartilage changes, even in the biologic era.

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Objective.Joint space narrowing (JSN) is a measurable outcome of tissue degeneration in arthritis. JSN is usually assessed by conventional radiography. Ultrasonographic (US) measurement of joint cartilage thickness has been validated in healthy children, and US measurement of the distal femoral cartilage has been validated in a group of patients with juvenile idiopathic arthritis (JIA). Our aim was to compare the measures of cartilage thickness of the proximal cartilage site in the second metacarpophalangeal (MCP), second proximal interphalangeal (PIP), and knee joints as assessed by US to joint space width (JSW) as measured by computerized radiography in children with JIA.Methods.The study included 74 children with JIA aged 5–15 years (median 11.3 yrs). MCP and PIP joints were assessed at one midline spot. Knee joints were assessed at the medial and lateral femoral condylar areas. Only the proximal cartilage site in the joints was assessed by US, whereas the complete JSW was assessed by radiography.Results.We assessed 136 second MCP, 138 second PIP, and 146 knee joints. We found a high level of agreement between US and radiographic measures of cartilage thickness and JSW: r = 0.82–0.86 (second MCP), r = 0.50–0.55 (second PIP), and r = 0.52–0.81 (knee); p < 0.001 for all 8 assessed sites.Conclusion.US measurements of cartilage thickness of the proximal site of the second MCP, second PIP, and knee joints correlated well with radiographic JSW measurements in the finger and knee joints of children with JIA. However, US does not measure the distal cartilage, which may limit its use in the assessment of JSN.