Stage IIIb is the locking phase of the lateral pole discal disease. In this situation, the lateral fifty percent of the disc is dislocated from the lateral pole. The condyle cannot translate beneath this portion of the disc. The medial pole still remains structurally intact. All structures at the lateral pole are diseased. It is not unusual for Stage IIIb patients to develop an asymptomatic lock. Hence, they may have a history of reduced mandibular vertical opening, or alternatively, they may have had intermittent locking at the lateral pole. However, as long as they are allowed to compress primarily their medial pole, where the disc is normally aligned, they may not develop significant intra-articular pain.