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CT designed (Bespoke) Facial Implants

Dr. Yaremchuk has innovated the use of custom facial implants for both aesthetic and reconstructive indications. Precise measurements obtained from CT scans allow Dr. Yaremchuk to design implants unique for the patient. These Computer Aided Designed (CAD) and Computer Aided Manufactured (CAM) or CAD/CAM implants are especially useful for patients with significant asymmetry and for patients who have had orthognathic surgery and are left with noticeable contour irregularities. Nuanced design not possible with "off the shelf" implants is possible with CAD/CAM implants. 


Indications and Advantages of CAD/CAM Implants

CAD/CAM provides added sophistication to facial implant surgery. It provides three dimensional, millimeter accuracy in implant design and manufacturing specific to the facial skeleton being addressed. This precision potentially minimizes or eliminates limitations intrinsic to the use of "off the shelf" implants and asymmetry of the facial skeleton. CAD/CAM implants are custom made or BESPOKE for the individual patient.

CAD/CAM implants are ideal for patients with significant facial asymmetry.Asymmetries are three dimensional. They can be thought of as twists of the skeleton. As demonstrated in figure 1  CT Figure 1

Figure 1 – Three dimensional of facial skeleton showing complex asymmetry.

The asymmetry in the mandible is more than an asymmetry in lower facial width. Note the difference in ramus height and border inclination. These implants are also useful to correct skeletal contour irregularities that result after orthognathic surgery. Please see Figure 2

Nuanced design is not possible with “off the shelf” implants, but is possible with CAD/CAM implants. Note the three dimensional change in the chin as well as correction of asymmetry in mandible body shown in the design shown in Figure 2.

 CT Figure 2

Figure 2 – CAD/CAM implant allows desired width, vertical elongation and sagittal projection of chin as well as correcting body asymmetry.

The precise fit of the CAD/CAM implant to the underlying skeletal contour makes for a more predictable result. A fundamental technical problem is placing bilateral implants in similar postions on opposite sides of the face as shown in the figure 3 here:  CT Figure 3

Figure 3


Remote incisions routinely provide limited access and therefore limited exposure of the areas to be augmented. Furthermore, the surgeon never has the ability to see the position of both implants in a single view. CAD/CAM implants are made to augment precisely defined areas of the facial skeleton making implant positioning less problematic. These implants can also be designed with registration features, for example, a flange on a malar implant that rests on the infraorbital rim or on the superior edge of the zygomatic arch.  CT Figure 4

Figure 4 – CAD/CAM implant design. Registration features allow symmetric placement.


Custom implants are designed to avoid any gaps between the posterior surface of the implant and the anterior surface of the skelton as shown in this figure 5.  CT Figure 5

Figure 5


Gaps are unavoidable when using off the shelf implants.These gaps add to the effective projection of the implant. A 2mm gap beneath a 3mm implant will result in an unanticipated 5mm in effective projection. An implant designed and manufactured to have its posterior surface mirror that of the underlying skeleton will avoid that unanticipated contour result.

Implant Development

CT scans are obtained provide DICOM data. Digital Imaging and Communication in Medicine (DICOM) is a standard for handling, storing, printing, and transmitting information in medical imaging. This data is used to create a 3D model of the facial skeleton or a 3 dimensional image.The three dimensional model allows the surgeon to craft with clay the desired implant configuration, The clay is then used as a prototype for the implant design (figure 6).  CT Figure 6

Figure 6

DICOM data can also be used to create a three dimensional image used for virtual design sessions between surgeon and software engineer to create an implant (figure 7)  CT Figure 7

Figure 7


This technique is preferred by Dr.Yaremchuk because it allows millimeter precision of design. The computerized design is then used to computerize manufacture an implant.

Dr. Yaremchuk’s Design Technique

Critical in the design process is to recognize the patient’s goals. They may desire to create angularity, provide symmetry, improve facial balance or correct irregularities. It is useful for the patient to provide photographs of people who have the desired look. Digital manipulation of patient images can be helpful. The patient should understand that these images are used as guides in the design process and not predictions of the surgical outcome. There is no algorithm which can translate a digitally created change in soft tissue to an implant design that will result in the outer contour change. Effective communications between surgeon and patient is invaluable to the design process.

Because the native facial skeleton is not symmetric, implant augmentation will provide a 'relative symmetry'. Chin implants should create symmetry relative to the midline structures – nasal radix, nasal septum, central incisors and central lip elements. This symmetry should extend from mental foramen to mental foramen. Lateral to the mental foramen, mandible implants should relate to the width of the upper face. For example, the extent of lateral augmentation of the mandible angles should relate to the lateral orbital rims in the same way.  CT Figure 8

Figure 8 - Design of chin/mandible implant. Note that chin component is symmetric to midline from mental foramen to mental foramen. The mandible angles are augmented in width relative to landmarks of the upper face (lateral orbital rim in this case).


Designing an implant for one side of the face and mirroring it to create an implant for the opposite side will create mandible symmetry only if the mandible and midface were symmetric prior to augmentation. When augmenting the midface, the goal is to achieve similar implant plus skeleton projection.  CT Figure 9

Figure 9 - Midface implants have been designed to create similar skeleton plus implant contours. The variability in implant thickness reflected by the differences in the color maps compensate for differences in native skeleton contour.


Because the contours of the midface will vary from one side to the other, mirroring one side to the other is unlikely to result in similar contours.

Clinical experience has taught Dr.Y aremchuk to control the design process. After voicing their goals and preferences, patient participation in the step by step design process has proved unrewarding.

The design process is inevitably prolonged, more expensive and often less rewarding.

3D CT scans can be arranged to be obtained on the day of consultation with Dr. Yaremchuk. The three dimensional image reveals the exact underlying skeletal anatomy of the patient. Since one's facial skeleton is the fundamental determinant of their appearance, it can be invaluable to patient understanding during the consultation.

Patient Examples

*This man underwent CAD/CAM implant augmentation of midface and lower jaw as well as rhinoplasty.  CT Patient 1

 CT Patient 1

 

* This patient with hemifacial microsomia had been treated with sagittal split osteotomy, horizontal chin osteotomy and later distraction osteogenesis in attempts to reconstruct a symmetric mandible.

CT designed custom implants were used to result in this improvement.

implant2

 

* This patient had custom implants placed to augment his deficient chin and mandible.

implant3

 

* This patient had undergone mandible angle reduction in the past. She disliked the new look and desired restoration of her angles.

Custom implants were designed to restore angles which provided the desired lower face width.

implant4