Condylar restoration after early TMJ fractures and functional appliance therapy. Part II: Muscle evaluation.

The aim of this study was to analyze and to describe the condition of the lateral pterygoid muscle during and after functional appliance therapy in children who had sustained condylar fractures. The treatment group consisted of 19 patients with an average age of 13.4 years, who had sustained a unilateral fracture at an average age of 8.4 years and had been treated functionally for 6 to 8 months. Muscle condition was assessed through axial soft tissue description. The volume and density of the lateral pterygoid muscle were measured in both groups and were compared on the basis of sex, age and fracture type. 74% of the patients in the follow-up group showed muscle differences of more than 10% between the 2 sides. In 2/3 of these patients the lateral pterygoid of the fracture side was 13 to 69% smaller. The volumes of the contralateral pterygoid muscles in the 2 patient groups differed by 10% on the basis of sex. Both in the treatment group and in the follow-up group the volume difference between the healthy and fractured side was as high as 70% depending on localization and type of fracture. Deep fractures and fractures with complete dislocation of the condyle evoked the most serious reduction in muscle volume.