Advantages of Custom TMJ Design
Model of Facial Skeleton
One of the advantages of a custom system is the familiarity of the patient’s anatomy that the design team develops throughout the generation of the anatomical model as well as the prosthesis design. Using OrthoTiN’s CT scan protocol results in scan data that best approximates patient anatomy and leads to a more accurate device. With an accurate representation of the patient’s maxilla and mandible anatomy, surgical planning becomes more accessible and reliable. Osteotomy planning, occlusion adjustment, and any patient specific considerations can be addressed. Also a 3D model can be printed for verification of the design as well as for surgical reference and planning.
Final implant fit to skull model with occlusion set (left); bilateral TMJ replacement--custom components for left and right TMJ ensure adequate fit (right)
Custom Ramus Component Allows Fit to Irregular Mandible
A standard flat surface on the ramus component may not be suited for patients who have irregularly shaped or mutilated skeletal anatomy. Custom components allow for control over the shape of the condylar component, the flexibility of positioning of the screws, and the adaptation of the internal surface. The specific design can be altered to increase fixation or improve positioning of the screws, to accommodate the best bone stock, bone thickness, or to account for the position of the mandibular nerve. If the occlusion can be improved by changing the position of the mandible, the design of the ramus component can be altered accordingly before surgery. Examples include mandibular advancement and lengthening of the posterior vertical height.
Regularly shaped mandible with standard implant (left); irregularly shaped mandible with custom fit implant (right)—custom implant prevents slipping and positions screws correctly
Custom Fossa Component Allows for Exacting Fit
A patient specific fossa component has the advantage over a standard component in that the implant is in direct contact at each point along the anatomical interface creating stability and reducing micromotion. This also reduces stress within the component by more efficiently transferring joint loads to the bone. In addition, there are certain circumstances in which the patient has anatomical deficits and a standard component cannot be used. All these advantages lead to a more robust and longer lasting joint replacement solution.
Custom fossa components for bilateral TMJ replacement set with trimmed UHMWPE bearing surfaces on model of patient skull