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Facial Prosthetics: An Evolving Field
From: ENT Today, February 2009
by Alice Goodman
Facial prosthetics can be a life-changing milestone for patients who have lost an eye, ear, or nose or sustained damage to intraoral structures. For many years, such people were forgotten patients who had to live with these obvious deformities. Many of them avoided social situations and interactions. But thanks to advances in science and technology, a near-normal appearance can be restored with a new prosthetic eye, ear, or nose.
Trauma (car accidents, burns, occupational accidents), head and neck cancer, and congenital defects are the most common reasons for full or partial loss of an eye, ear, nose, jawbone, or other head and neck structures. Patients faced with these defects may be able to choose between surgical reconstruction and prosthetic reconstruction, depending on the location and size of the defect. Sometimes the decision is between a prosthesis and nothing at all, for people who live in rural areas and/or lack insurance coverage. But even if people have geographical access to a center of excellence and the financial means to avail themselves of the best possible care, they may choose to live with a deformity rather than to have the hassle of cleaning and replacing a prosthetic device on a daily basis.
-Betsy Davis, DMD, MS
Under ideal circumstances, creating a well-fitted facial prosthesis with an excellent cosmetic result requires a team effort of an array of specialists, each focusing on an area involved in maxillofacial rehabilitation. Depending on whether the defect is extraoral or intraoral and on the extent of the defect, these specialists will include head and neck surgeons, facial plastic surgeons, maxillofacial prosthodontists, and medical artists or anaplastologists. Speech pathologists, physical therapists, nutrition counselors, and other rehabilitation counselors are called in to address functional and quality-of-life considerations with both surgical and prosthetic rehabilitation.
Getting state-of-the-art treatment depends on the team available to the patient. Not everyone has access to an ablative surgeon, a plastic surgeon, a maxillofacial surgeon, or a maxillofacial prosthodontist, said Joseph Huryn, DDS, Chief of the Dental Service at Memorial Sloan-Kettering Cancer Center in New York. Dr. Huryn's practice is focused on cancer patients, who may have lost part of a jaw, teeth, and other intraoral structures as a result of ablative surgery for head and neck cancer.
State of the Art
-Roman Skoracki, MD
-Joseph Huryn, DDS
Traditionally, facial prostheses were hand-sculpted. CAD/CAM (computer-assisted design/computer-assisted manufacture) techniques have revolutionized the field. A CT scan images the anatomical defect and computer-assisted rapid prototyping stores the measurements layer by layer in an electronic file; these are used to create an intermediate wax pattern for a machine-made model. Once a wax model is made, a medical artist-usually an anaplastologist-sculpts the model to match the facial contours and the skin tone of the recipient using computer-aided measurements to create a lifelike prosthetic device as perfectly matched as possible.
Technology is transforming the field of facial prosthetics. Software programs [e.g., Mimics and SurgiCase, Materialise, Ann Arbor, MI] allow the clinician the ability to design the contour of the prosthesis virtually. Color measurement programs of the skin aid in matching all the prosthesis to the skin. Virtual surgical planning software enhances the surgical outcome, said Betsy Davis, DMD, MS, Associate Professor of Otolaryngology-Head and Neck Surgery and Associate Professor of Oral and Maxillofacial Surgery at the Medical University of South Carolina in Charleston.
Most facial prostheses are made of silicones. Over the years, silicones have become more flexible and lifelike, Dr. Huryn said. However, silicone devices have a limited lifespan, usually around two years. It is possible to make several prostheses from the same mold if the patient's lifestyle suggests that a replacement will be needed sooner rather than later.
The lifetime of the prosthesis depends on the patient's job and environment. For example, a homebody may have a prosthetic ear that lasts for five or six years, while a farmer or a telephone line worker may need a new one within two years, Dr. Huryn said.
The facial tissues [surrounding the area where the prosthesis will be placed] are captured in dynamic and static states to be sure the prosthesis will sit right, Dr. Huryn explained. The measurements and pattern are stored electronically for future use, but the surrounding tissues may undergo changes over time that call for a new updated moulage (i.e., impression of the patient's face or missing anatomic defect).
Retention of the Prosthetic Device
Osseointegration is another state-of-the-art advance, explained Gregory G. Gion, MMS, a clinical anaplastologist and founder of Medical Art Prosthetics in Dallas. The ability to anchor prosthetic devices to the bone is the most important prosthetic development over the past few decades, Mr. Gion said.
Adhesives were traditionally used to retain many types of prosthetic devices. Irritation, perspiration, and movement can compromise the bond. Many people will still use adhesives because they may not be candidates for osseointegrated implants or due to reimbursement issues for osseointegration.
People have trouble with the idea of using adhesives. It is time-consuming and must often be done every day. People who depend on adhesives may only wear the device on special occasions, explained Roman Skoracki, MD, Assistant Professor in the Department of Plastic and Reconstructive Surgery at M. D. Anderson Cancer Center in Houston.
Sometimes silicon pieces impregnated with magnets can be used to retain the prosthesis, but osseointegration offers the most secure option. In osseointegration, titanium screws are placed surgically into the craniofacial skeleton, and posts or magnets are screwed into the top of these screws. Magnets that attach to these abutments are placed on the prosthetic device. In the cancer setting, the titanium screws can be implanted into the bone by the plastic surgeon or oral and maxillofacial surgeon after the surgical site has been prepared by an ablative surgeon.
Replacing defective intraoral structures requires the skill of a maxillofacial prosthodontist. Dr. Davis explained the typical procedures for intraoral prostheses.
For patients who have lost a portion of the hard palate, an obturator will enhance functional outcomes of speech, swallowing, and chewing. When the mandible is resected for cancer, a free tissue transfer with the fibula allows placement of dental implants. A resection appliance supported by dental implants replaces the lost dentition, she said.
Use of the fibula free flap was pioneered at Memorial Sloan-Kettering, Dr. Huryn said. This procedure entails removing the fibula (not a weight-bearing bone, he noted) and carving the bone to mimic the shape of the lower jaw. Teeth are implanted into the bone, allowing the patient to chew and swallow normally.
Dr. Davis described a palatal lift, which is used to restore velopharyngeal competence for patients whose soft palates don't move. Patients who have soft palate insufficiency can have a speech bulb prosthesis to allow speech and swallowing. Palatal augmentation devices can be placed if part of the tongue has been resected; this procedure lowers the palatal floor to make contact with the tongue and enables swallowing, she said.
Who Should Have a Prosthetic Device?
The decision between surgical reconstruction and a prosthetic device is based on a number of factors, including age, cormorbidities, general health status, patient preference, and reimbursement. In general, larger defects are more amenable to a surgical reconstruction. Older, medically compromised patients may prefer prosthetics, whereas younger patients tend to opt for surgical reconstruction when possible, Dr. Davis said.
In the cancer setting, indications for prosthetics depend largely on patient preference. A significant proportion of patients don't pursue prosthetic procedures. They will just use a patch over a missing eye. If the ear is missing, they will accept living with a flat spot, and they may just leave the nose defect as is. Some people choose to wear surgical masks to avoid stares. It can be a reimbursement issue, or they may not be candidates for prosthetic rehabilitation, or simply, cancer patients may be tired of surgery, Dr. Skoracki said.
Mr. Gion said that a prosthesis is advisable for a head and neck cancer patient who needs ongoing monitoring of the area of the face at risk for recurrence. Some surgical reconstructions are too complicated to attempt-an ear, for example-and in that situation a prosthetic device is preferable.
Prosthetic devices are not a good choice for patients with poor vision and poor manual dexterity who may not be capable or motivated to manage the prosthetic and clean it, Mr. Gion continued.
Another important consideration is access to rehabilitation, Dr. Huryn noted. A military patient may have a prosthetic device procedure at a state-of-the-art hospital, but then go home to a rural area where rehabilitation is not available. In that case, a prosthetic device may not be a good option, he commented.
Interviewees agreed that a critical component for success is a correctly prepared foundation for a facial prosthesis. A prosthetic device won't work if the area of the defect is not prepared to accept the prosthesis. For example, we need a socket that will accept a prosthetic eye. The surgeon creates the environment that will accept an orbital prosthesis, Dr. Davis explained.
The foundation for the prosthesis may be inadequate due to radiation, or it may be too voluminous and require more debulking. This is where the plastic surgeon comes in, Dr. Skoracki said.
Extraoral prosthetics requires close collaboration. A team approach is best. At our university, we collaborate to plan resection, reconstruction, and rehabilitation, Dr. Davis commented.
You need a team approach involving interested parties. Each specialist brings something more to the table. We learn from each other, and we learn from every patient. These procedures should be done at a center with sufficient volume, an appropriate infrastructure, and a dedication to the restoration of the patient as a whole, Dr. Skoracki added.
First, consider both surgical and prosthetic options with the patient, Dr. Davis advised. Patients should be shown a visual catalog of the types of prostheses available and the options for retention, and given an idea of how they will look with and without a facial prosthesis. Certain types of defects are better approached by surgical reconstruction-for example, the nose- while the ear is usually more amenable to a prosthesis, she said.
If the patient is able to discuss the procedure beforehand, it is important to explain what the amputation of an eye, nose, or ear will mean. Help the patient understand how a prosthesis will aid in their recovery, but tell them that the prosthesis will never be the same as normal tissue, Dr. Skoracki said.
Patients need to have realistic expectations of a prosthetic device. These are not live tissues, and they are not capable of functioning as such. A new eye won't blink. No matter what the extraoral prosthesis looks like, it will not be functional, Dr. Huryn said.
Facial prosthetics is not a well-known specialty. Patients will need to be educated about prosthetic choices and attachment options. They will need an anaplastologist who concentrates only on the face so they can be satisfied with the results. An excellent result is not automatic, Mr. Gion stated. Even ear reconstructive surgeons such as R. L. Walton agree that 'the weak link in this technology [prosthetic rehabilitation] lies in the quality of the prosthesis itself, the life-like appearance of which is wholly dependent on the artistry and skill of the anaplastologist.'
Also, patients will need to be prepared for taking care of the prosthetic device-attaching, removing, and cleaning it.
Patients need to know that prostheses have a limited life span. They should be aware that they may need a new moulage and a different prosthesis if the soft tissue around the prosthesis undergoes changes, Dr. Huryn said. This may entail a procedure to redo the flaps for placement of the prosthesis.
Future developments in the field will come from tissue engineering and 3D imaging with CAD/CAM technology, according to experts interviewed for this article.
The field is evolving. It may be possible someday to bioengineer more complicated structures than those we can produce now, for example, to encourage growth of new bone, blood vessels, and skin, Dr. Huryn suggested. The possibilities are mind-boggling.
©2009 The Triological Society