Objectives. 1) Virtual bilateral TMJ reconstruction from magnetic resonance (MR) imaging of 28 children (age range: 2.7 - 16.9) with juvenile idiopathic arthritis (JIA) by means of state-of-the-art software and 2) quantitative intra- and interindividual comparison of joint deformation.
Methods. MR sections of all joints were assessed by two pediatric radiologists and reconstructed using Amira™. Subjects were divided into three age groups and two diagnostic groups (no/mild vs. severe deformation). After ascertaining normal distribution, intra- and interindividual joint comparisons were performed with ANOVA and ttests at α=0.05. Parameters not differing between sides and/or plane orientation were averaged intra-individually.
Results. Significant differences among age groups were found for: steepness of the anterior fossa slope (p=0.003), condylar volume (p=0.007), intercondylar angle (p=0.008), direct and curvilinear length of the anterior fossa slope (p=0.047 resp. 0.009) and medio-lateral condylar diameter (left p=0.023, right p=0.017). Severely deformed TMJs had a smaller intercondylar angle (p=0.009) and a shallower anterior fossa slope (p=0.021) than normal or mildly deformed joints.
Conclusion. Virtual 3D-reconstruction of TMJs of JIA children is feasible without ionizing radiation, but requires time and special skills. Across age groups and independent of radiological disease evidence, measurements on virtual models reflected morphological changes observed with conventional radiography during growth. Due to limited patient numbers in each age group, diagnostic (sub)groups could only be formed across all subjects. 3D-parameters of severely deformed joints seem to reflect altered joint growth and development. Future studies with larger cohorts may reveal further differences and should include healthy controls.