2.1.3. Design of Fossa Prosthesis

Fitting the skull is a major problem in TMJ reconstruction patients because of the irregular shape of their TMJs [14,15] The patient-specific design approach enables developing accurately fitting models for the complex shape of patient's fossa-eminence anatomy. Using a similar design approach discussed earlier for the condylar implants, patient-fitted custom designs of fossa prosthesis can be developed such that the device fits accurately to the available host bone. Such custom designed fossa implants can correctly adapt to the natural components of patient's TMJ, and provide improved stability through locking screws and perforated notches fitting into patient's skull. Figures 13–21 show different shapes and features of our custom-designed fossa prostheses.

shapes and features of our custom-designed fossa prostheses.

shapes and features of our custom-designed fossa prostheses.

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**Figure 13.** A simple custom-design of the fossa prosthesis with screw holes. (**A**) Demonstrates that the implant is designed for optimal usage of natural fossa eminence for fixation using screws. (**B**,**C**) Show different views of the implant illustrating the custom shape accurately conforms to the contours of host anatomy. The implant has constant thickness throughout its body, and the shape of articulating surface is same as that of the natural articular surface. **Figure 13.** A simple custom-design of the fossa prosthesis with screw holes. (**A**) Demonstrates that the implant is designed for optimal usage of natural fossa eminence for fixation using screws. (**B**,**C**) Show different views of the implant illustrating the custom shape accurately conforms to the contours of host anatomy. The implant has constant thickness throughout its body, and the shape of articulating surface is same as that of the natural articular surface. **Figure 13.** A simple custom-design of the fossa prosthesis with screw holes. (**A**) Demonstrates that the implant is designed for optimal usage of natural fossa eminence for fixation using screws. (**B**,**C**) Show different views of the implant illustrating the custom shape accurately conforms to the contours of host anatomy. The implant has constant thickness throughout its body, and the shape of articulating surface is same as that of the natural articular surface.

to the natural components of patient's TMJ, and provide improved stability through locking screws and perforated notches fitting into patient's skull. Figures 13–21 show different

to the natural components of patient's TMJ, and provide improved stability through locking screws and perforated notches fitting into patient's skull. Figures 13–21 show different

patient's natural fossa and eminence. The rectangular slot (with curved anterior and posterior edges) in inferior surface of the implant is designed to provide sufficient rotation and opportunity for anterior-posterior and medio–lateral translation of the matching prosthetic condylar head. The articular grove is designed such that it would prevent dislocation of the prosthetic condylar head during functional movements of the jaw. Visuals in (**D**,**E**) show that the superior surface of the implant is designed to accurately match the shape of natural fossa. Sufficient thickness is maintained **Figure 14.** Patient-fitted design of a fossa prosthesis. (**A**–**C**) Illustrate accurate fit of the device to the patient's natural fossa and eminence. The rectangular slot (with curved anterior and posterior edges) in inferior surface of the implant is designed to provide sufficient rotation and opportunity for anterior-posterior and medio–lateral translation of the matching prosthetic condylar head. The articular grove is designed such that it would prevent dislocation of the prosthetic condylar head during functional movements of the jaw. Visuals in (**D**,**E**) show that the superior surface of the implant is designed to accurately match the shape of natural fossa. Sufficient thickness is maintained **Figure 14.** Patient-fitted design of a fossa prosthesis. (**A**–**C**) Illustrate accurate fit of the device to the patient's natural fossa and eminence. The rectangular slot (with curved anterior and posterior edges) in inferior surface of the implant is designed to provide sufficient rotation and opportunity for anterior-posterior and medio–lateral translation of the matching prosthetic condylar head. The articular grove is designed such that it would prevent dislocation of the prosthetic condylar head during functional movements of the jaw. Visuals in (**D**,**E**) show that the superior surface of the implant is designed to accurately match the shape of natural fossa. Sufficient thickness is maintained for the lateral portion of implant to pre-drill screw holes which can host locking screws for better fixation and stability.

**Figure 14.** Patient-fitted design of a fossa prosthesis. (**A**–**C**) Illustrate accurate fit of the device to the

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fixation and stability.

nence and bone situation.

**Figure 15.** Patient-specific design of fossa prosthesis. Inferior rectangular surface of the device has a circular grove for articulation with condylar head (**A**,**B**). Visuals illustrate customized size and shape of the device for accurate fit and fixation (**C**,**D**) to native anatomical structure. Superior edge of the lateral surface (which hosts screw holes) is custom cut to follow the curvature of native eminence and bone situation. **Figure 15.** Patient-specific design of fossa prosthesis. Inferior rectangular surface of the device has a circular grove for articulation with condylar head (**A**,**B**). Visuals illustrate customized size and shape of the device for accurate fit and fixation (**C**,**D**) to native anatomical structure. Superior edge of the lateral surface (which hosts screw holes) is custom cut to follow the curvature of native eminence and bone situation. **Figure 15.** Patient-specific design of fossa prosthesis. Inferior rectangular surface of the device has a circular grove for articulation with condylar head (**A**,**B**). Visuals illustrate customized size and shape of the device for accurate fit and fixation (**C**,**D**) to native anatomical structure. Superior edge of the lateral surface (which hosts screw holes) is custom cut to follow the curvature of native eminence and bone situation. **Figure 15.** Patient-specific design of fossa prosthesis. Inferior rectangular surface of the device has a circular grove for articulation with condylar head (**A**,**B**). Visuals illustrate customized size and shape of the device for accurate fit and fixation (**C**,**D**) to native anatomical structure. Superior edge of the lateral surface (which hosts screw holes) is custom cut to follow the curvature of native emi-

for the lateral portion of implant to pre-drill screw holes which can host locking screws for better

for the lateral portion of implant to pre-drill screw holes which can host locking screws for better

the implant. **Figure 16.** Patient-fitted fossa implant with circular inferior surface which also has a circular grove for articulation with condylar head. Visuals in (**A**–**D**) demonstrate the customized size and shape of the implant. **Figure 16.** Patient-fitted fossa implant with circular inferior surface which also has a circular grove for articulation with condylar head. Visuals in (**A**–**D**) demonstrate the customized size and shape of the implant. **Figure 16.** Patient-fitted fossa implant with circular inferior surface which also has a circular grove for articulation with condylar head. Visuals in (**A**–**D**) demonstrate the customized size and shape of the implant.

uniquely designed articulating surface/hole is slanted in anterior direction. This anterior slope of **Figure 17.** Patient-specific design of fossa prosthesis (**A**,**B**). The device has a rectangular grove (with curved anterior and posterior edges) in its inferior surface for articulation with condylar head. The uniquely designed articulating surface/hole is slanted in anterior direction. This anterior slope of **Figure 17.** Patient-specific design of fossa prosthesis (**A**,**B**). The device has a rectangular grove (with curved anterior and posterior edges) in its inferior surface for articulation with condylar head. The uniquely designed articulating surface/hole is slanted in anterior direction. This anterior slope of articulating surface is intended to provide opportunity for anterior translation of the condylar head during movements of mandible. This feature of our fossa prostheses provides an advantage over currently available total TMJ implants which, when implanted, only rotate but do not translate during functional movements of the patient's jaw [19].

articulating surface is intended to provide opportunity for anterior translation of the condylar head during movements of mandible. This feature of our fossa prostheses provides an advantage over currently available total TMJ implants which, when implanted, only rotate but do not translate dur-

ing functional movements of the patient's jaw [19].

**Figure 18.** Custom-designed fossa prosthesis with circular articular surface. The device shown in (**A**,**B**) has relatively smaller articulating circular hole compared to the one shown in (**C**,**D**). Additionally, articulating surface of the device shown in (**C**,**D**) is slanted anteriorly to augment anterior translation of condylar head during mastication. **Figure 18.** Custom-designed fossa prosthesis with circular articular surface. The device shown in (**A**,**B**) has relatively smaller articulating circular hole compared to the one shown in (**C**,**D**). Additionally, articulating surface of the device shown in (**C**,**D**) is slanted anteriorly to augment anterior translation of condylar head during mastication.
