Lateral impingements of the temporomandibular joint: a classification system and MRI imaging characteristics

Finite element analysis of dynamic temporomandibular joint (TMJ) loading reveals a predominance of localization of loading laterally towards the collateral ligament regions and disc/capsule attachments to the mandibular condyle. A previous publication (Kirk, Kirk. OMS Clin North Am 2006;18:345-68) introduced biomechanical principles for surgeons to consider in the diagnostic phase of management as well as initial surgical procedure selection. The concept of impingements and their impact with development of derangement is presented in this paper with an expanded collection of imaging characteristics. Diagnostic coronal imaging using a dual photon imaging technique is presented. This technique is superior to traditional T1 and T2 weighted imaging sequences when sagittal imaging is employed. Coronal imaging using this technique adds a new dimension to preoperative imaging. Impingement presence and the discernment of early lateral disc/capsule rupture from the condyle of the mandible is superior with the dual photon technique. Images and a classification of degrees of impingement are presented. The biomechanical importance of diagnosis of impingement is discussed.