Synovial plica, lateral impingement and intra-articular impingement/entrapment pathologies of the temporomandibular joint

Abstract

Synovial plicae are common findings in most knees and extremity joints. However, plicae of the temporomandibular joint (TMJ) have not been adequately addressed. In the cadaver study, various plicae were observed with histologic findings in the research base, and clinically plica were detected in patients with internal derangement, recurrent luxation and other operative diseases in recent years. Although the incidence of a synovial plica varies between 24% with 62%, the prevalence is unknown because of not detectable by MRI. Plicae in recurrent dislocation cases are relatively thick, wide and pliable with histology of dense fibrous/hyalinized tissues with scattered chondroid cells. In cases with internal derangement, plicae were thin pliable, and finger-or band-like with histology of fibrous tissues and/or inflamed synovium with vascular proliferation suggesting in pathogenesis. Although plicae may or may not be causing symptoms, when detected during surgery should be removed with other intraarticular pathologies for restoring the biological function of TMJ. In development of TMJ lateral impingement, the lateral capsular prolapse may play an important role. The soft tissues of the capsule become fibrotic and constricted with inflammation restricting mandibular movement. Early adhesive capsulitis appears as an adherent finger-like plica vascularized from the lateral capsule restricting movement of the attached disc. Plica lined with synovium combined with a deformed disc induce mechanical abrasion resulting synovitis, which may induce chondromalacia leading to deterioration of bone and joint. The release of adhesions along the lateral aspect of the capsule is performed, then lateral capsular stretching and repositioning of prolapsed synovial plica is favorable to obtain good outcomes. The term "entrapment" generally refers to a compression of a peripheral nerve or artery usually between ligamentous and bony structures. Whereas symptomatic synovial impingement and intra-articular synovial entrapment syndromes have been well documented in patient undergone total arthroplasty and joint replacements of the hip and knee. There is strong evidence that the TMJ is susceptible to the same symptomatic impingement and intra-articular synovial entrapment as other synovial joints. This review of our current state of knowledge will accelerate and update the evolution of further understanding of TMJ pathologies, diagnosis and treatment.

Synovial entrapment in alloplastic temporomandibular joint replacement

“…This phenomenon has also been confirmed in the TMJ, related to internal derangement 16,17 . It was described for the first time in TMJ alloplastic devices by Westermark et al 7 as a dense, fibrous connective tissue without signal of inflammatory cells or foreign body reactions and synovial-like tissue between the capsule and disc observed in TMJ prosthesis revision (Biomet Microfixation and TMJ Concepts).…”