Temporomandibular joint (TMJ)
TMJ is the joint between the lower jaw and the skull. It is due to this joint function that we are able to move the lower jaw in open-close, side to side, back and forth movements. Its peculiarity as compared to other joints of the body is that both joints (right and left) function simultaneously and hence when one is affected the entire lower jaw movement is affected. The lower jaw moves every time we swallow our saliva, while speaking, chewing, yawning and so on
Temporomandibular joint ankylosis is a fusion between the condylar head of the lower jaw and the skull. This restricts the mobility of the lower jaw and hampers all activities of the lower jaw viz. swallowing, speaking, chewing, yawning, etc. Mouth opening gets reduced and progressively increases in severity such that it ceases to open at the end. TMJ is also the growth centre for lower jaw and hence growth is also affected in these individuals.
It is usually caused due to recurrent middle ear infections (reduced due to progress in antibiotics), trauma to the chin in childhood, birth trauma – forceps delivery (reduced due to advances in obstetric practices). Currently, trauma forms the major etiology of TMJ ankylosis.TMJ ankylosis results in severe facial and functional deformity.
Management of this particular problem includes releasing the ankylosis so to achieve mouth opening as well as correcting the facial deformity resulting due to growth disturbance. Mouth opening is achieved by cutting bone and creating a gap at the region of the joint and placing some material to separate the cut bony surfaces. Most commonly, muscle is used.
TMJ ankylosis released to achieve mouth opening:
Correction of the deformity can be done by orthognathic surgery or distraction osteogenesis. Distraction is preferred due to formation of new bone in this technique and superior stability of results achieved.