Imaging of the temporomandibular joint (TMJ) in children is most often performed in the setting of juvenile-idiopathic arthritis (JIA). Children with JIA may have active inflammatory changes including joint effusions, synovial thickening and hyperenhancement, and more chronic changes of condylar flattening, osseous erosions and disc pathology. Other TMJ pathologies which may be seen in children include: septic arthritis, post-traumatic joint arthropathy, congenital abnormalities and other less common entities. Unlike adults there is a range of normal developmental changes that are seen when imaging the pediatric TMJ. The purpose of this exhibit is to review normal TMJ anatomy and development seen on pediatric imaging, review the findings of TMJ pathology in JIA and discuss the less common pathologies that affect the pediatric TMJ.
Educational Goals / Teaching Points
The goals of this exhibit are to familiarize radiologists with normal pediatric TMJ anatomy and developmental changes; differentiate these normal findings from TMJ pathology; and to characterize TMJ pathology. We will start with a review of the normal anatomy of the pediatric TMJ. Part of this discussion will be a review of the normal developmental changes that occur at the mandibular condyle during childhood that involve both changes in condylar morphology and the transition of hematopoietic to fatty marrow. Next, we will describe and illustrate the imaging findings of various pathology that occurs at the TMJ in JIA and review a recent Outcome Measures in Rheumatology (OMERACT) scoring system that has been developed to better standardize MRI reporting. Finally, the imaging findings of less common pathologies will be demonstrated.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The TMJ can be imaged with radiographs, ultrasound, CT and MRI. Various imaging modalities will be used to illustrate normal anatomy and pathology with a discussion of their strengths and weaknesses. However, MRI is considered the gold standard for TMJ imaging because it provides the most complete evaluation of the soft tissues and osseous anatomy. This allows MRI to detect the range of TMJ pathology seen in JIA, which includes inflammatory changes (e.g., joint effusion, synovial thickening, and bone marrow edema) and osseous changes (condylar flattening and erosions). We will review how these features fit into and are scored in the OMERACT scoring system.
Radiologists interpreting pediatric TMJ imaging need to be aware of developmental changes that occur throughout childhood so that these normal changes are not confused with pathology. Furthermore, it is important to be familiar with recent attempts to standardize MRI reporting of TMJ pathology in JIA to provide rheumatologists with information with which they can better assess disease severity and treatment response.