THE RELATIONSHIP BETWEEN TEMPOROMANDIBULAR-JOINT MOBILITY AND PERIPHERAL JOINT MOBILITY RECONSIDERED

The purpose of this paper was to study the relationship between temporomandibular joint (TMJ) mobility and mobility of joints and to study the general character of joint mobility in 83 subjects, 55 females and 28 males (mean age 26.7, range 13-46 years). The subjects were recruited from the Department of Oral and Maxillofacial Surgery of the University Hospital of Groningen. All participants had a good general health and did not present anamnestically, clinically or radiographically TMJ disorders. Of these subjects, angular displacement of the mandible relative to the cranium during maximal mouth opening (AMO) was measured. Furthermore, the maximal range of motion of passive digit five hyperextension, passive thumb apposition to the wrist, active elbow and knee hyperextension, active ankle dorsal flexion and trunk flexion were measured. All measurements were performed bilaterally, except trunk flexion. Calculation of product moment correlations (Pearson) revealed a weak relationship between AMO and mobility of right digit five and elbows for the total group and between AMO and mobility of both digits five and elbows for women. The correlations were never stronger than 0.4. Multiple regression revealed that only 25.9% of the total variance of AMO could be explained by mobility of peripheral joints, age and sex. Calculation of product moment correlations between mobility of peripheral joints, trunk flexion and age revealed weak correlations between the different joints, with the exception of paired joints. Principal component analysis revealed a weak general character of joint mobility. It is concluded that mobility or hypermobility of the TMJ cannot be predicted on the basis of mobility or hypermobility of other joints and that mobility of any peripheral joint cannot be predicted on the basis of the degree of mobility of other joints.