Experimental Study on Anatomic Reduction of Lateral Pterygoid Muscle(Simulated Manipulation Fracture Reduction)and Condylar Free Reduction for Condylar Fracture

[Objectives]To compare the fracture healing of keeping lateral pterygoid muscle anatomic reduction(simulated manipulation fracture reduction)with condylar free reduction in the treatment of condylar fractures.[Methods]Twenty-four New Zealand rabbits were randomly divided into two groups to mandibular condylar neck fracture model was established.one team keep the lateral pterygoid muscle,the other excise it.Cervical vascular perfusion was done with ink before animals executed after operation 2,4,6 and 8 weeks.Bilateral anteroposterior and mediolateral condylar diameters measured.Changes of operation side condylar proliferating layer,microvessel number and bone parameters were observed and analyzed after slices and HE staining.[Results]The mediolateral condylar diameters of operation side were significantly smaller than health side in condylar free reduction group at the 4,6,8 weeks(P<0.05),but there was no statistical difference in the anteroposterior condylar diameters at each time point(P>0.05).There were no significant differences in the anteroposterior and mediolateral condylar diameters of the anatomic reduction lateral pterygoid muscle group compared between the operation side and health side(P>0.05).The number of microvessel in condylar free reduction group were smaller than those in anatomic reduction lateral pterygoid muscle group(P<0.05).There were significant differences in BV/TV,Tb.Th,Tb.Sp between the condylar free reduction group and the anatomic reduction lateral pterygoid muscle group(all P<0.05),and the Tb.N were significantly differences between two groups at the 4,6,8 weeks(P<0.05).[Conclusions]When the condyle is fractured it should keep lateral pterygoid muscle(manipulation fracture reduction)as possible,which is important in the fracture healing and functional recovering of mandibular.