Modified Temporomandibular Joint Replacement Surgery With Lateral Pterygoid Muscle Preservation Techniques

PURPOSE: The function of lateral pterygoid muscle(LPM)will be severely impaired after traditional temporomandibular joint(TMJ)replacement surgery,resulting in mouth opening deviation,limited lateral movement of mandible and restricted mouth opening.To solve this problem,we carried out this study to explore a modified TMJ replacement surgery which can preserve the maximum function of LPM.Meanwhile we took an attempt to develop a method to match the CT/MRI images of LPM with the help of the three-dimensional(3-D)reconstruction techniques.METHODS: We imported the CT/MRI image data of condyle and LPM into Mimics 18.0 to do the three-dimensional reconstruction.Then a matching between CT 3-D images and MRI 3-D images,taking the cortical bone of condyle as reference,was performed to obtain high resolution 3-D images of LPM and condyle and to precisely locate the position of the attachment between LPM and condyle.Two new LPM preservation techniques were proposed and a consecutive follow-up was carried out to evaluate theirs effectivity and reliability.RESULTS: The reconstructed 3-D image of LPM from CT data possess subtle details and vividly displayed the run and patterns of LPM.While the MRI 3-D image of LPM has a distinct demonstration of the margin of LPM and the attachment between LPM and condyle.The precise location of LPM attachment was revealed by matching CT 3-D images and MRI 3-D images of LPM,taking the cortical bone of condyle as reference.The one-year consecutive follow-up of 6 series cases showed an inspiring result of mouth opening recovery and improving range of lateral mandibular movement.Postoperative CT scan showed a satisfying bone healing and almost normal LPM patterns.CONCLUSIONS: Comparing with using CT/MRI examination method alone,the matching of CT and MRI 3-D images can exert the best of the both examination methods to precisely locate the attachment between condyle and LPM,thus assisting the accurate osteotomy,even the digital surgical plates guided osteotomy,to make the surgery procedures more precise.The CT/MRI matching method may inspire other investigators on medical imaging merging.The results of follow-up were inspiring and possess a promising application prospect.