Ultrasound measurement of cartilage thickness in childhood arthritis--target the tissue, tailor the technique

Ultrasound-guided determination demonstrates influence of age, sex and type of sport on medial femoral condyle cartilage thickness in children and adolescents

PURPOSE

To analyse the reliability of ultrasound-guided measurement of the cartilage thickness at the medial femoral condyle in athletically active children and adolescents before and after mechanical load in relation to age, sex and type of sport.

METHODS

Three successive measurements were performed in 157 participants (median/min-max age: 13.1/6.0-18.0 years, 106 males) before and after mechanical load by squats at the same site of the medial femoral condyle by defined transducer positioning. Test-retest reliability was examined using Cronbach'sα $\alpha $ calculation. Differences in cartilage thickness were analysed with respect to age, sex and type of practiced sports, respectively.

RESULTS

Excellent reliability was achieved both before and after mechanical load by 30 squats with a median cartilage thickness of 1.9 mm (range: 0.5-4.8 mm) before and 1.9 mm (0.4-4.6 mm) after mechanical load. Male cartilages were thicker (p < 0.01) before (median: 2.0 mm) and after (2.0 mm) load when compared to female cartilage (before: 1.6 mm; after: 1.7 mm). Median cartilage thickness was about three times higher in karate athletes (before: 2.3 mm; after: 2.4 mm) than in sports shooters (0.7; 0.7 mm). Cartilage thickness in track and field athletes, handball players and soccer players were found to lay in-between. Sport type related thickness changes after mechanical load were not significant.

CONCLUSION

Medial femoral condyle cartilage thickness in childhood correlates with age, sex and practiced type of sports. Ultrasound is a reliable and simple, pain-free approach to evaluate the cartilage thickness in children and adolescents.

LEVEL OF EVIDENCE

Level III.

Reliability of ultrasonography to detect inflammatory lesions and structural damage in juvenile idiopathic arthritis

BACKGROUND

Musculoskeletal Ultrasonography (MSUS) is an important tool for the clinical assessment in Juvenile Idiopathic Arthritis (JIA). The objective of this study was to evaluate the reliability of MSUS to detect elementary lesions: synovitis, tenosynovitis, cartilage damage and bone erosions in the wrist and metacarpal (MCP) joints of patients with JIA.

METHODS

Thirty children in various subgroups of JIA according to ILAR criteria, were included in this cross-sectional study. Clinical data including painful, swollen and limited joints were recorded. Five rheumatologist ultrasonographers, blinded to the clinical evaluation, evaluated the presence of elementary lesions in the wrist and MCP 2 and 3 joints bilaterally. The synovitis was graded in B-Mode and Power Doppler (PD). In addition to descriptive statistics intra- and inter-observer reliability was calculated using Cohen's kappa according to Landis and Koch.

RESULTS

US detected more synovitis than the clinical examination (62% vs 28%, 30% vs 23% and 22% vs 17% in the wrist, second and third MCP joints respectively). The intra-observer concordance for synovitis in all joints was excellent in B-Mode (k 0.84 .63-1.0 p = 0.001), except for MCP 2, where it was good (0.61, IC 95% .34-89, p = 0.001). For both modalities (PD, B-Mode) tenosynovitis, cartilage damage and bone erosions it was also excellent. Regarding synovitis grading the concordance was excellent for all grades (0.83-1.0, IC 95% 0.51.1.0, p = 0.001), except for grade 1 where it was good (0.61, IC 95% 0.43-.83, p = 0.001). Reliability inter-observer for grayscale synovitis (0.67-0.95, IC 95% 0.67-1.0, p = 0.001), tenosynovitis grayscale (0.89, IC 95% 0.78-0.99, p.001), damage cartilage (0.89, IC 95% 0.78-0.99, p = 0.001), PD (0.66, IC 95% 0.39-1.0, p = 0.001). The concordance for grading synovitis was excellent, but for grayscale grade 1 and 2 (.66, IC 95% .53-.74, p = 0.007) and PD grade 1 and 2 (0.63, IC 95% .58-.91, p = 004) was good.

CONCLUSIONS

The intra- and inter-observer reliability of MSUS for inflammatory and structural lesions is good to excellent for the wrist and MCP in patients with JIA.

Juvenile idiopathic arthritis - the role of imaging from a rheumatologist's perspective

Alongside recent advances in treatment strategies for juvenile idiopathic arthritis (JIA), paediatric rheumatologists have taken increasing interest in the use of imaging. Magnetic resonance imaging (MRI) and musculoskeletal ultrasound, by providing more detailed information on disease activity than clinical examination and conventional radiography (CR), have become helpful diagnostic and managerial tools. The growing skeleton, however, with changing appearances over time, is still challenging in the establishment of valid scoring systems for pathological changes. Defining child- and age-specific reference standards is therefore a highly prioritized issue. The aim of this article is to raise awareness among radiologists of the substantial role that imaging can play to optimize the management of JIA patients and to describe the state-of-the-art validation process of imaging as an outcome measure. A closer collaboration between radiologists and pediatric rheumatologists is crucial to define a scheduled workflow for imaging in JIA.

Establishing percentile charts for hip joint capsule and synovial cavity thickness in apparently healthy children

BACKGROUND

The usefulness of musculoskeletal ultrasonography (MSUS) in paediatric population is limited by lack of reference values. One of such parameters is hip joint capsule thickness, postulated as an early measure for synovitis. However, the joint capsule is hardly a distinguished structure from slit synovial cavity in patients with little or no fluid collection. Therefore, in patients without effusion, it is more convenient to measure hip joint capsule thickness together with synovial cavity. The aim of the study was to establish percentile chart for hip joint capsule and synovial cavity thickness (HJC&SCT) in apparently healthy children.

MATERIAL AND METHODS

The analysis included 816 US of hip joint in 408 children without musculoskeletal disorders, distributed equally throughout the whole developmental period in 18 one-year subgroups. Hip joints US was performed according to standard protocol including measurement of HJC&SCT in a single rheumatology centre by three investigators.

RESULTS

The 3rd, 10th, 25th, 50th, 75th, 90th, and 97th HJC&SCT percentile curves were depicted in the age and height charts for the combined group of girls and boys. The median HJC&SCT values were increasing with age from 3.7 (C10 - C90: 3.3 - 4.2) mm in the first year of life up to 6.7 (5.8 - 7.3) in 16 years old, and above. In a similar way the increase was seen with height from 3.9 (3.5 - 4.7) mm in shorter than 95 cm to 6.9 (6.2 - 7.4) mm in taller than 169 cm subjects. Intra-observer and inter-observer mean precision was less than 1.8 and 12.5%, respectively.

CONCLUSION

The developed centile chart for hip joint capsule and synovial cavity thickness in the paediatric population is expected to improve detection of hip joint capsule disorders, including synovitis in juvenile idiopathic arthritis.

Ultrasound in juvenile idiopathic arthritis

BACKGROUND

In the recent years, musculoskeletal ultrasound (MSUS) has been regarded as especially promising in the assessment of juvenile idiopathic arthritis (JIA), as a reliable method to precisely document and monitor the synovial inflammation process.

MAIN CONTENT

MSUS is particularly suited for examination of joints in children due to several advantages over other imaging modalities. Some challenges should be considered for correct interpretation of MSUS findings in children, due to the peculiar features of the growing skeleton. MSUS in JIA is considered particularly useful for its ability to detect subclinical synovitis, to improve the classification of patients in JIA subtypes, for the definition of remission, as guidance to intraarticular corticosteroid injections and for capturing early articular damage. Current evidence and applications of MSUS in JIA are documented by several authors. Recent advances and insights into further investigations on MSUS in healthy children and in JIA patients are presented and discussed in the present review.

CONCLUSIONS

MSUS shows great promise in the assessment and management of children with JIA. Nonetheless, anatomical knowledge of sonographic changes over time, underlying immunopathophysiology, standardization and validation of MSUS in healthy children and in patients with JIA are still under investigation. Further research and educational efforts are required for expanding this imaging modality to more clinicians in their daily practice.