Piper Classification - Stage IIIa

In Stage III there is a more chronic displacement of the disc from the lateral pole. Stage IIIa is the clicking phase of the lateral pole discal displacement. In this scenario, there is greater laxity of the lateral collateral ligament and of the lateral portion of the retrodiscal attachment. The lateral portion of the retrodiscal attachment is also more redundant than normal. In addition, fibrosis begins to develop at the lateral portion of the superior belly of the lateral pterygoid muscle. This results in chronic clicking because of displacement of the disc from the lateral pole of the condylar head. The medial fifty percent of the articular space still has normal alignment of all tissues. Realize that in centric relation the primary loading of the joint is at the medial pole, and hence these people typically do not have discomfort with compression. Depending upon the degree of tissue alteration at the lateral pole this lateral pole clicking can be chronic, or alternatively, the clicking disc can be reduced. The more ideal the intra-articular anatomy, the more likely this Stage IIIa can be reduced back to a Stage I. On the other hand, if there is more fibrosis of the lateral pterygoid muscle, redundancy of the retrodiscal attachment, discal deformity, or a bone deformity, then it is less likely that the disc can be reduced. In this case, the disc may chronically click, or it may begin a locking phase.