33 Facial prosthetics in plastic surgery

Gordon H. Wilkes, Mohammed M. Al Kahtani, Johan F. Wolfaardt

Synopsis

The success of osseointegration biotechnology has revolutionized facial prosthetic reconstruction.

Titanium is the implant material of choice as it is light, biocompatible, and resistant to corrosion.

Implant placement technique is crucial to produce bone–implant contact with no interposed fibrous tissue and successful bone healing.

Appropriate treatment selection requires understanding of all options available.

Multidisciplinary team planning is required.

Osseointegration biotechnology provides plastic surgeons with more treatment options for challenging head and neck deformities.

Deformities in the head and neck region can have a profound effect on the function, aesthetics, and psyche of an individual. Considerable time, effort, and ingenuity have been spent trying to develop meaningful reconstructive solutions to a wide variety of craniofacial defects. Autogenous reconstruction remains the gold standard, but in certain cases, autogenous reconstruction may be contraindicated, technically impossible, or have the potential to solve the reconstructive issues only partially.

Historically facial prosthetics have been of limited benefit. Retention of facial prostheses has been largely unsuccessful because of the need for adhesives or crude mechanical means of maintaining retention. The patient lacked confidence about the positioning of the prosthesis and its ability to stay in place. Often associated pain or discomfort would limit the length of time and circumstances in which the prosthesis would actually be worn. The adhesives are those used in industry and were not developed for the unique sensitive human biological environment. They often had adverse effects on the underlying skin compromised by radiotherapy, trauma, or thermal injury ¹ and affected the durability and longevity of the prosthesis.

With the success of osseointegration and its ability to solve the problem of prosthetic retention,^2,³ a new treatment modality was now available.^4,⁵ Prosthetic longevity is increased without the need for adhesives.^6,⁷ Osseointegrated retained facial prosthetics now meet the necessary criteria for success: (1) aesthetic acceptability; (2) functional performance; (3) biocompatibility; and (4) desired retention.⁸ The use of osseointegration biotechnology in facial prosthetic restoration has been hailed as the most significant advance in the field of facial prosthetics in the past 25 years.⁹ It is estimated that more than 90 000 implants have been installed extraorally in more than 45 000 patients up to the year 2007.¹⁰

Craniofacial osseointegrated reconstruction gives the plastic surgeon another viable treatment option in many challenging head and neck defects.¹¹ It can provide some patients with a meaningful and enhanced quality of life when in the past other treatment options would not have been successful. Unfortunately, competing specialties or providers have presented autologous techniques and craniofacial osseointegration as unrelated technologies.¹² Osseointegrated and autogenous techniques should not be viewed as competing technologies, but rather as complementary reconstructive procedures that optimize the opportunity for success in the management of major head and neck deformities.

Why this situation has arisen is unclear. In some cases, it appears to be due to a lack of understanding of osseointegration and its benefits. It may be viewed only as a salvage procedure when all else has failed and both the patient and surgeon are desperate. It is not viewed as “real” surgery, only as throwing a few screws in the bone. Those in doubt cannot understand how patients would be satisfied with a prosthesis, “a foreign object that never becomes part of their body image.” To any surgeon with experience in osseointegration, these lines of thinking are seriously flawed.

This intervention requires long-term support by both the caregiver and the funder for maintenance of the implant sites as well as future prosthetic construction. It is analogous to the time and financial commitment required in an organ transplantation program.

Historical perspective

Historically, implants in bone were largely unsuccessful and had a poor reputation for long-term success. In the 1950s, Professor Brånemark, from Goteborg, Sweden, discovered titanium behaved somewhat differently from other metals when in contact with bone. The first osseointegrated implant was placed in a human in 1965. The term “osseointegration” was coined by Brånemark in 1977.¹³ It is defined as the direct contact – structural and functional – between ordered living bone and the surface of a load-bearing implant. Osseointegration is a dynamic process that involves micromodeling at periosteal and endosteal surfaces and remodeling at the bone–implant interface.^8,^10,¹⁴ This principle of osseointegration ultimately led to the development of successful dental implants.¹⁵ Albrektsson et al. further postulated that a skin-penetrating implant may be possible.¹⁶ Implants were first placed in the mastoid region to support a bone-anchored hearing aid in 1977 and to retain an auricular prosthesis in 1979¹⁷ (Fig. 33.1). Subsequently, numerous reports have confirme the efficacy and predictability of craniofacial osseointegration.^18,¹⁹ The concept of anchoring craniofacial prosthesis on osseointegrated implants was accepted by the Food and Drug Administration (FDA) in 1985. The FDA accepted the concept of anchoring hearing aids on implants in adults in 1995 and children in 1998. In 1985, implants were used in hand surgery to anchor joint replacements and in the early 1990s the concept was used for anchoring prostheses in amputees’ fingers, hands, arms, and legs.

Fig. 33.1 Historical development of osseointegration biotechnology. Through the Brånemark experience, osseointegrated implants have been subjected to over 30 years of scientific scrutiny. Craniofacial applications were first introduced in 1977. EO, extraoral.

Advantages of craniofacial osseointegration

Craniofacial osseointegration has many advantages (Box 33.1).²⁰ The surgical procedures are generally short with minimal morbidity and are performed on an outpatient basis. There is a short learning curve and results are predictable. The patients usually have minimal postoperative discomfort. Examination of the tumor resection site is easy and allows early diagnosis of any tumor recurrence.

Craniofacial osseointegration can successfully salvage a patient with a failed autogenous reconstruction and often offers superior aesthetics. When compared with adhesive-retained facial prosthetics, osseointegration offers predictable prosthetic retention, increased prosthetic durability and lifespan, enhanced prosthetic aesthetics, ease of displacement, no underlying skin damage, successful incorporation of the prosthesis into the body image, and a happier, more satisfied patient. Osseointegration can also be considered in diabetics and smokers.

The disadvantages of craniofacial osseointegration include the need for a larger multidisciplinary team with skills that are often not freely available. Patients also require regular maintenance visits and a new prosthesis every 2–5 years (Box 33.2).²⁰ Lifetime ongoing costs can be an issue with some insurance companies.

Box 33.2

Disadvantages of craniofacial osseointegration ⁷

Need for multidisciplinary team

Need for reliable, committed patient

Ongoing expense of prosthetic remakes and maintenance visits

Not one’s own tissue

Indications for craniofacial osseointegration

Craniofacial osseointegration can be of particular benefit for reconstruction of selected defects involving the ear, orbit, nose, and combined midfacial defects. The osseointegrated implants have also been used to secure hairpieces.²¹ A newer application of interest to the plastic surgeon is the use of a bone-anchored hearing aid (BAHA) in children with microtia. In the past concern has been expressed combining a BAHA and an autogenous ear reconstruction. Fear of inappropriate positioning of the implant adversely affecting future autogenous ear reconstruction usually prevented patients having the benefits of both treatment modalities. This usually resulted in the BAHA being placed too far posterior or not being considered at all. Certainly the BAHA is an excellent option for hearing restoration in bilateral microtia patients and more recently has proven of benefit in unilateral microtia patients (Fig. 33.2). It is a much more straightforward, safer, and predictable way of improving hearing than previous autogenous means of canalplasty and middle-ear reconstruction.¹⁰

Fig. 33.2 Bone-anchored hearing aid (BAHA) and autogenous ear reconstruction for microtia.

Ear reconstruction

Autogenous reconstruction of auricular defects has improved greatly in the latter half of the 20th century because of the work of pioneers such as Tanzer,²² Brent,²³^–²⁶ Fukada and Yamada,²⁷ Cronin,²⁸ Bauer,²⁹ Yanai et al.,³⁰ Isshiki et al.,³¹ Nagata,³²^–³⁴ and others. Certainly, not all reconstructive attempts are successful. The appropriate treatment selection for major ear defects continues to be controversial (Table 33.1).²⁰ Certain auricular defects have limited autogenous options, particularly after removal of the ear for cancer with associated radiotherapy. It is our belief that these reconstructive techniques are complementary and must be presented in this manner.^8,^12,²⁰ Definite indications for osseointegrated auricular prosthetic reconstruction include: (1) following major cancer resection; (2) radiotherapy to the proposed site of auricular reconstruction; (3) severely compromised local tissue (Fig. 33.3); (4) patient preference; and (5) salvage procedure for failed autogenous reconstruction. Relative indications include: (1) microtia; (2) absence of the lower half of the ear; and (3) patients with calcified costal cartilage.

Table 33.1 Indications for osseointegrated ear reconstruction ⁷

Definitive	Relative
Major cancer resection	Microtia – most controversial
Radiotherapy	Absence of lower half of the ear
Severely compromised tissue	Calcified costal cartilage
Patient preference
Failed autogenous reconstruction
Potential craniofacial anomaly
Poor operative risk

Fig. 33.3 (A–C) Reconstruction following severe electrical injury included cranioplasty, free-flap scalp coverage, and ear reconstruction with implant-retained prosthesis.

Probably the most controversial indication for osseointegrated auricular reconstruction is microtia in children. Although it is technically possible to place implants in children as young as 3 years and early results are encouraging, the follow-up in these situations is short. Because the use of craniofacial osseointegrated implants requires removal of any local ear remnants and produces scarring in the operative field, future autogenous reconstruction options are very limited. For these reasons, the use of osseointegrated auricular reconstruction in the pediatric age group requires very careful consideration by the clinician and family (Fig. 33.4). A publication by Zeitoun et al.³⁵ outlines the difficulties seen using osseointegration in the pediatric population. It also showed an increased need for psychological support in many of these patients. Our approach is to offer autogenous ear reconstruction to pediatric patients with microtia. Despite the potential for difficult treatment selection decisions, we rarely find this to be the case. Patients usually decide quite quickly after the possibilities are discussed. It is rare for patients to change their mind following further discussion.

Fig. 33.4 (A, B) Ear loss and severe local tissue trauma secondary to dog attack in a child. Reconstructed with implant-retained prosthesis.

The use of an adhesive-retained auricular prosthesis is very limited and almost relegated to historical significance only. It certainly cannot be considered a “test” for an osseointegrated prosthesis. It offers none of the major advantages of implant-retained prostheses such as ease of placement, predictable retention, improved aesthetics, increased lifespan of the prosthesis, and no ongoing insult to the skin.

Osseointegrated nasal reconstruction

Indications for osseointegrated nasal reconstruction include: (1) failed autogenous reconstruction; (2) significant scarring in potential autogenous donor sites (Fig. 33.5)⁶; (3) tumor recurrence following initial autologous reconstruction; and (4) patient preference (Box 33.3). Because of the need for multiple surgical stages and the greater variability in the ultimate result with autogenous reconstruction, many patients with total nasal loss opt for placement of implants and a nasal prosthesis (Fig. 33.6). Certainly, there is less surgery involved with less morbidity. There is no need for other donor sites, and tumor surveillance is easy with prosthesis removal.⁸ The application of “nontraditional” long zygomaticus implants may be useful in difficult situations of nasal reconstruction.³⁶

Fig. 33.5 (A, B) A Simplant™ study can be performed to determine quantity and quality of underlying bone.

Box 33.3

Indications for osseointegrated nasal reconstruction ¹⁰

Failed autogenous reconstruction

Scarring at autogenous donor sites

Reconstruction following autogenous reconstruction because of tumor recurrence

Patient preference

Medical contraindication to multistaged autogenous reconstruction

Fig. 33.6 (A–D) Nasal deformity following cancer resection reconstructed with implant-retained nasal prosthesis.

Osseointegrated orbital reconstruction

Patients with loss of the orbit and orbital contents have very poor autogenous reconstructive options (Box 33.4). Although autogenous coverage may be necessary to cover important neurological structures, in many cases it is provided only to fill the residual orbital cavity. However, “filling the hole” does not create an aesthetic result. It is in these situations that osseointegrated orbital reconstruction clearly has advantages over autogenous reconstruction. The aesthetic results are far superior and again allow visualization for early tumor recurrence (Fig. 33.7). This approach could also be considered in patients with severe enophthalmos and significantly compromised vision. Less frequently, it can be considered in patients with an ocular prosthesis and significant eyelid distortion secondary to trauma or radiotherapy that is not amenable to autogenous correction. The hope for the future would be to create an orbital prosthesis that can mimic movement of both the lids and globe of the opposite normal eye.¹³

Box 33.4

Indications for osseointegrated orbital reconstruction

Loss of orbit and orbital contents

Severe enophthalmos with compromised vision

Difficulty with an ocular prosthesis and significant eyelid distortion secondary to trauma or radiotherapy that is not amenable to autogenous correction

Fig. 33.7 (A–C) This patient had an orbital exenteration for a malignancy and was reconstructed with an implant-retained orbital prosthesis.

Midfacial reconstruction

Patients with complex facial defects that may include the orbit, nose, and maxilla again have poor autogenous options (Fig. 33.8). Craniofacial osseointegration offers significant advantages. It enables examination of the posttumor defect and allows for a very acceptable aesthetic result. In the patient shown in Figure 33.8 it allowed early detection of a recurrence on the posterior orbital wall. Treatment consisted of surgical removal and reconstruction with a temporoparietal fascial flap and skin graft. The patient was able to resume wearing his prosthesis again only 12 days after surgery to resect the recurrence. Extraoral osseointegration in combination with intraoral osseointegration may also result in significantly improved functional results over conventional prosthetic or autogenous techniques.

Fig. 33.8 (A, B) This patient had an extensive basal cell carcinoma invading his orbit, nasal region, and maxilla. After surgical extirpation, implants were later placed and a naso-orbital prosthesis constructed. Autogenous options were poor.

Factors important to obtain osseointegration ^13,³⁷

Choice of implant material

Many materials have been considered for osseointegration. Although other metals such as vanadium, tantalum, aluminum hydroxide, and ceramics like hydroxyapatite are known to integrate with bone to a certain degree, titanium is currently the material of choice.³⁷ Titanium is relatively light but stiffer than bone. Its springiness allows it to flex with the bone. The most important factor is the ability of its titanium oxide layer on the implant surface to react with the adjacent bone (its biocompatibility). The key to success is what happens at this implant–tissue interface. The most successful is commercially pure titanium, which is 99.75% pure. This differs from the most commonly used titanium alloy, which contains 90% titanium, 6% aluminum, and 4% vanadium, and exhibits much less satisfactory characteristics of osseointegration.