Sphenoethmoid cerebrospinal fluid leak repair with hydroxyapatite cement.

Despite advances in neurological, reconstructive, and endoscopic sinus surgery, sphenoethmoid cerebrospinal fluid (CSF) fistulae continually pose difficult management problems. Standard surgical techniques for fistulae closure succeed approximately 78% to 90% of the time. To improve this success rate, hydroxyapatite cement (HAC), a Food and Drug Administration-approved substance for cranial defect repair, was applied to this problem in a clinical setting. Twenty-one patients with spontaneous, posttraumatic, or postoperative CSF leaks of the sphenoid sinus, cribriform plate, or ethmoid region were treated with HAC. Study participants were prospectively accrued at 5 tertiary care medical centers in the eastern United States. The CSF leaks of all 21 patients treated with HAC were successfully sealed by its initial application. The sites of CSF leakage included the nasal cavity (n = 2) and sphenoid sinus (n = 19). Fifteen of the patients had previously undergone a failed repair by standard methods. There have been no recurrent CSF leaks with a maximum follow-up of 72 months, and an average follow-up of 36 months. All patients have survived to date. The only HAC-related morbidity was the extrusion of the HAC when placed in the nasal cavity. Hydroxyapatite cement is an effective method of repair for postoperative, posttraumatic, and spontaneous sphenoid CSF leaks. The efficacy of HAC in sealing the CSF leak was unaffected by previous attempts at leak closure by standard methods or by its origin. Hydroxyapatite cement should not be applied transnasally for the treatment of an ethmoid region fistula owing to its high probability of extrusion. Correct patient selection and technical familiarity with HAC are necessary for successful application.

Tympanic membrane repair with a dermal allograft.

OBJECTIVES: To assess the use of an acellular dermal allograft in the repair of chronic tympanic membrane perforations. Chronic tympanic membrane perforations are a common problem in otolaryngology, and although surgical tympanoplasty using either temporalis fascia or rice paper has proven to be highly successful, these materials are not without their own limitations. The search has continued for a simpler, yet equally effective, means of repairing persistent tympanic membrane perforations in an office setting. In this study we experimentally evaluated the use of an acellular dermis (AlloDerm, (LifeCell Corporation, The Woodlands, TX) as an alternative to traditional tympanoplasty materials. STUDY DESIGN: Prospective study using 28 adult chinchillas. METHODS: Subtotal tympanic membrane perforations were created bilaterally in 28 adult chinchillas. Animals with noninfected, stable perforations that showed no signs of epithelial regeneration after 5 to 8 weeks were used to compare the use of rice paper patch with AlloDerm in patch tympanoplasties. RESULTS: Eighteen of 23 tympanoplasties (78%) that were performed using AlloDerm showed no signs of perforation after 5 to 6 weeks. In those performed using rice paper control, 14 of 21 (66%) showed no signs of perforation after 5 to 6 weeks. In addition, histological evaluation of the healed tympanic membranes demonstrated that the acellular dermis had been incorporated within the middle fibrous layer of the tympanic membrane. CONCLUSIONS: The results and histological studies suggest that acellular dermis may be a suitable alternative to traditional materials currently used for patch tympanoplasty. Future studies to evaluate the efficacy of acellular dermis in humans are warranted.

Acellular dermis for facial soft tissue augmentation: preliminary report.

OBJECTIVE: To evaluate the efficacy of acellular dermis as a viable alternative for soft tissue augmentation in facial reconstruction. DESIGN: A prospective, nonrandomized observational study consisting of 10 patients who underwent soft tissue augmentation with acellular dermis. SETTING: A tertiary care university medical center in an urban setting. PATIENTS: Ten patients who had undergone soft tissue augmentation using acellular dermis participated in this study. Postimplantation follow-up was 17 to 36 months. INTERVENTION: The amount and location for placement of the acellular dermis was left to the discretion of the surgeon. All implants were placed in the subdermal tissues. MAIN OUTCOME MEASURES: The adequacy of acellular dermis for soft tissue augmentation was assessed by subjective evaluation of implant volume persistence, postoperative complications, and the restoration of normal contour. RESULTS: Of 10 patients who underwent implantation, 9 had no complications and 1 had a recurrent sterile abscess or mucocele at the implantation site. A 22-month postimplantation tissue sampling of acellular dermis in a patient with recurrent tumor revealed approximately 80% to 85% volume persistence. CONCLUSION: Preliminary experience with acellular dermis indicates that it shows promise in soft tissue augmentation.

Morphological and phase characterizations of retrieved calcium phosphate cement implants.

A self-hardening calcium phosphate cement (CPC), consisting of equimolar amounts of tetracalcium phosphate and dicalcium phosphate anhydrous, hardens when mixed with water and forms a resorbable hydroxyapatite (HA) as the end-product. The objective of this study was to investigate the changes of the phase and morphology of the CPC during hardening and aging under in vivo conditions. CPC samples retrieved 12 h after hardening in vivo had already contained carbonated HA (type B), even though the initial cement mixture did not contain carbonate as one of the solid components. The mass fraction of carbonate in the 12-h sample was about 1%. The results suggested that under in vivo conditions carbonate is readily available and this allows formation of carbonated HA in favor of carbonate-free HA. The carbonate content of the CPC samples retrieved 3 months after implantation was similar to that of the 12-h samples, and the exterior surfaces of the 3-month samples appeared less crystalline than that of the 12-h samples.

The use of acellular dermis in the prevention of Frey's syndrome.

EDUCATIONAL OBJECTIVE: At the conclusion of this presentation, the participant should be able to discuss the indications and advantages of using acellular dermis in the prevention of post-parotidectomy gustatory sweating (Frey's Syndrome). INTRODUCTION: Gustatory sweating is a common postoperative problem and a challenge to treat. The purpose of this study was to evaluate the role of acellular dermis in preventing post-parotidectomy gustatory sweating. METHODS: Sixty-four patients were randomly assigned to two groups. Group I consisted of 32 patients who underwent a superficial lobe parotidectomy. Group II consisted of 32 patients who underwent a superficial lobe parotidectomy and underwent intraoperative placement of acellular dermis within the parotid bed, between the skin flap and the remaining parotid tissue. The implanted volume of acellular dermis was determined by the amount required to aesthetically restore lateral facial contour. All 64 patients were evaluated for gustatory sweating by identical phone and mail questionnaires. Thirty randomly chosen patients (group I = 15, group II = 15) were evaluated using a modified Minor's Starch-Iodine Test (MSIT). In all 30 patients, the MSIT was administered to both sides of the face. RESULTS: The responses to questionnaires (N = 64) demonstrated the subjective presence of gustatory sweating in 3 of 32 patients (9.3%) in group I, whereas group II demonstrated a subjective incidence in 1 of 32 patients (3.1%). The objective incidence determined by those who underwent the MSIT (n = 30) revealed a 40% (6) and 0% incidence of Frey's Syndrome in groups I and II, respectively. The complication rate in group I was 9% (3 seromas) and in group II it was 25% (7 seromas and 1 wound infection). CONCLUSIONS: Acellular dermis appears to be an effective method for preventing post-parotidectomy gustatory sweating, despite its higher complication rate.

Human dural replacement with acellular dermis: clinical results and a review of the literature.

BACKGROUND: The search for the ideal dural replacement in the setting where autogenous tissues are unavailable or inadequate still persists. Because of the ability of acellular dermis (AlloDerm, LifeCell Corporation, The Woodlands, TX) to remodel itself into native tissue, this dynamic quality is hypothesized to occur when used as a dural replacement. METHODS: We report the long-term outcome of a small cohort of patients who, to our knowledge, were the first patients to receive AlloDerm for dural replacement. In addition, to put these current findings in a historical perspective, we present a review of the literature for dural replacement. RESULTS: Ten patients all successfully underwent duraplasty with AlloDerm with only one postoperative complication that was not related to the acellular dermal dural repair. CONCLUSIONS: We contend that AlloDerm is a safe and viable option for dural replacement in cases in which autogenous tissues are either unavailable or insufficient for proper reconstruction.

Applications of fast-setting hydroxyapatite cement: cranioplasty.

A variety of autogenous and synthetic materials have been used to repair cranial defects resulting from traumatic and iatrogenic causes. In theory, the ideal material should be readily available and safe. It should adequately protect the underlying central nervous system, resist cerebrospinal fluid fistula formation, and be easily contoured. One promising synthetic biomaterial that has been used for cranioplasty is hydroxyapatite cement. This biomaterial has successfully restored cranial contour in most patients in whom it has been used; however, difficulties have arisen because of the material's prolonged water solubility. When exposed to cerebrospinal fluid or blood, inadequate setting of the cement occurs, resulting in loss of its structural integrity. This problem can be alleviated with the use of fast-setting hydroxyapatite cement, which hardens 6 to 12 times faster than the traditional cement. We present, to the best of our knowledge, the first series of the use of this material in 21 patients requiring cranioplasty. The advantages and limitations of fast-setting hydroxyapatite cement will be discussed.

Reconstruction of the frontal sinus and frontofacial skeleton with hydroxyapatite cement.

OBJECTIVE: To evaluate the efficacy of a newly developed biomaterial, hydroxyapatite cement, for use in frontal sinus and anterior craniofacial skeletal reconstruction. DESIGN: A nonrandomized patient cohort that was compared with historical controls of standard treatment with methyl methacrylate implants. SETTING: Craniofacial reconstructive surgery services at 3 referral health care centers. Eligible patients had frontal-cranial defects limited to a maximum size of 25 cm2. Patients were randomly selected volunteers with preexistent, acute traumatic or acute surgically induced defects of the frontal sinus and anterior craniofacial skeleton. All patients provided informed consent, and the study was approved by the 3 institutional review boards. Forty patients underwent reconstruction of defects of the anterior craniofacial region, and 38 of these patients were evaluable at 24 months. MAIN OUTCOME MEASURES: Hydroxyapatite cement was used to reconstruct full-thickness anterior craniofacial skull defects. Standard surgical techniques were used to place all implants. The primary outcome measurement was maintenance of implant volume determined at 24 months by computed tomography and clinical examination. Secondary outcome measures included incidence of complications and infections necessitating implant removal. RESULTS: Of the 38 evaluable patients, 31 had successful reconstructions at the end of the study, for an overall success of 82% for frontal sinus and frontofacial region reconstruction. Seven patients underwent explantation, 5 for surgical access to the site. Two implants were removed because of infection in the wound, for an overall incidence of approximately 5%. Explant biopsy specimens confirmed implant osseointegration and vascularization. CONCLUSIONS: Hydroxyapatite cement successfully reconstructs full-thickness defects of the frontal sinus and frontofacial region at 24 months. Hydroxyapatite cement appears to be superior to acrylic implants for frontal-cranial reconstruction and by allowing implant osseointegration with improved biocompatibility.

Use of the peritracheal fold in the dog tracheal transplantation model.

OBJECTIVE: To investigate the technical aspects of the canine model of human tracheal transplantation for potential application to reconstruction of extremely long tracheal defects (> 10 cm). DESIGN: In phase 1, long tracheal segments were skeletonized and pedicled with the thyroid glands, cranial thyroid arteries and veins, and internal jugular vein branches. The segments were elevated completely, attached to the vascular pedicle only, and replaced with primary tracheal anastomoses. In phase 2, long segments were elevated along with a diffuse soft tissue "blanket" that envelops the trachea and thyroid glands. Because this study was designed to primarily address, in situ, tracheal perfusion territories of a cranially located vascular pedicle, microvascular anastomoses were not conducted. SUBJECTS: Two small-bodied beagles (10-15 kg) and 5 large-bodied mixed-breed dogs (20-30 kg) were humanely killed 2 to 41 days after surgery, and anatomic and histological analyses were conducted. RESULTS: Unlike that of humans, the thyroid gland complex of dogs is not intimately associated with the trachea but is conjoined with a peritracheal soft tissue "fold." Within this fold, blood is transmitted to the trachea via a diffuse, segmental vascular plexus. In phase 1, pronounced tracheal necrosis occurred within 2 to 5 days. In phase 2, extremely long tracheal segments (10-12 cm), based only on a cranially located pedicle, were still viable at 2 to 6 weeks. CONCLUSIONS: Preservation of the "peritracheal fold" in the dog model of tracheal transplantation is critical to the onset and maintenance of vascular perfusion in a long tracheal segment. Furthermore, the use of large-bodied dogs is necessary to provide for a usable venous efflux component.

Use of an acellular dermal allograft for dural replacement: an experimental study.

OBJECTIVE: In this study, a nonimmunogenic, acellular, dermal collagen matrix termed XenoDerm (LifeCell Corp., The Woodlands, TX) was examined for use as a dural replacement material in a porcine model. This model was used to investigate whether AlloDerm (LifeCell), an almost identical material made from human dermis, could be safely used in neurological surgery. METHODS: Bilateral temporoparietal dural defects were surgically created in 12 Yucatan minipigs. One side was repaired with autologous pericranium, and the other was repaired with XenoDerm. The pigs were killed after 1, 3, or 6 months, and the areas of dural repair were collected and examined macroscopically and histologically. XenoDerm is derived from porcine skin collected in thin sheets. It is processed so that the epidermis and all dermal cells are removed without disruption of the collagen matrix, rendering the material immunogenically inert and resistant to calcification. It is packaged as a freeze-dried sheet and is easily rehydrated at the time of surgery. RESULTS: There were no postoperative complications, and all pigs survived. Both grafts performed well as dural replacements in all cases. There was no macroscopic evidence of inflammation or cerebrospinal fluid leakage. The XenoDerm grafts were intact, retained their original dimensions, and resembled the surrounding dura. The autologous pericranial grafts, in contrast, were thicker than when implanted and had bony excrescences firmly adhering to their surfaces. Again, however, there was no evidence of cerebrospinal fluid fistulae. There was no gross adherence to the underlying meninges or brain tissue in any specimen. Repopulation by fibroblasts and neovascularization were evident in the XenoDerm grafts as early as 1 month after surgery; by 3 months, the XenoDerm had been remodeled to assume the connective tissue appearance of the surrounding dura. CONCLUSION: In this porcine model, an allograft of acellular dermis is a nearly ideal dural replacement. AlloDerm, the human equivalent of XenoDerm, would be an allograft of acellular dermis after implantation in human subjects. On the basis of this study and previous work with AlloDerm in other reconstructive applications, it is proposed that this material could be similarly used for duraplasty in human subjects.

Imaging central skull base neural tumor spread from paranasal sinus malignancies: a critical factor in treatment planning.

Eight cases of paranasal sinus tumors with central skull base disease are presented. Each patient had coned down noncontrast and contrast-enhanced magnetic resonance imaging (MRI) studies to evaluate the tumor margins and any potential tumor spread into the cavernous sinuses, V2 and the Vidian nerve. Two patients had tumors that extended up to the face of the sphenoid bone and one had a tumor in the ventral cavernous sinus. These three patients had a complete tumor resection with postoperative irradiation. Two more patients had extensive tumor invasion of the central skull base, one was treated with only irradiation, one refused treatment. Three more patients had tumors that involved the ventral portion of the sphenoid bone with limited neural tumor extension. Two of these patients had surgery with cavernous sinus dissections followed by irradiation. One patient delayed treatment for 2 months and when he returned he had a more extensive tumor and was considered incurable by surgery. He refused further treatment. The technique of the focused MR examination and its impact on treatment planning is discussed.

Current use of bone substitutes in maxillofacial surgery.

The use of bone substitutes in the field of facial plastic and reconstructive surgery is well established. Because of the complexity of the anatomy in the head and neck region, reconstruction and augmentation of this area pose a challenge to the surgeon. In addition, the shortcomings of autogenous bone, such as resorption and donor site morbidity, have led to the need for alloplastic implants in the field of facial plastic surgery. Multiple alloplastic implants are currently in use today; however, those compounds that contain calcium, silicon, and carbon have been examined more closely in this article. This is because of their ability to osseointegrate and osseoconduct with surrounding fibro-osseous tissue, as well as demonstrate a higher immunogenic tolerance by the human body. The discussion of each compound includes a description of its composition and structure, the advantages and shortcomings of the material, and its current uses in the field of facial plastic and reconstructive surgery. With a better understanding of the available alloplastic implants, the surgeon can make a more informed decision as to which implant would be most suitable in a particular patient.

BoneSource hydroxyapatite cement: a novel biomaterial for craniofacial skeletal tissue engineering and reconstruction.

BoneSource-hydroxyapatite cement is a new self-setting calcium phosphate cement biomaterial. Its unique and innovative physical chemistry coupled with enhanced biocompatibility make it useful for craniofacial skeletal reconstruction. The general properties and clinical use guidelines are reviewed. The biomaterial and surgical applications offer insight into improved outcomes and potential new uses for hydroxyapatite cement systems.

Complications of microvascular head and neck surgery in the elderly.

OBJECTIVES: To evaluate the complications of head and neck reconstruction using microvascular free tissue transfers (MFTTs) performed in an elderly population and to determine whether these complications are more common than in a younger population. SETTING: Tertiary referral center. PATIENTS AND DESIGN: Retrospective, consecutive chart review of patients older than 70 years who underwent MFTT in the past 5 years (group 1). The complications in this population were compared with those in a second group (group 2) of consecutive patients younger than 70 years who were matched according to the site of the primary tumor. MAIN OUTCOME MEASURES: Surgical and medical complications. RESULTS: The median age for group 1 was 74 years and for group 2, 55 years. The overall complication rate for group 1 was 48%, compared with 57% for group 2. In group 1, surgical morbidity was less common and medical morbidity was more common than in group 2. Mortality rate was 6% for group 1 and 0% for group 2. The types of complications were similar for both groups. There was no difference in complication rates when complications were classified by site of the defect, patient status determined by American Society of Anesthesiologists classification, or use of preoperative radiation. The overall success rate of MFTT was 100% for group 1 and 94% for group 2. CONCLUSIONS: Microvascular free tissue transfers for head and neck reconstruction can be safely performed in the elderly. An age older than 70 years does not increase the rate of surgical complications following head and neck reconstruction with MFTT. Medical complications, however, are more common and are equally divided between bronchopulmonary and cardiovascular effects.

Hydroxyapatite cement in craniofacial skeletal reconstruction and its effects on the developing craniofacial skeleton.

OBJECTIVE: To assess the effects of hydroxyapatite cement (HAC) on the developing feline craniofacial skeleton. DESIGN: Fronto-orbital craniotomies were performed on 14 kittens and reconstructed by autograft or HAC. By design, animals in which the craniofacial skeleton was reconstructed with HAC also underwent obliteration of the left frontal sinus. After achievement of skeletal maturity, animals were sacrificed and compared by 11 standardized cranial measurements obtained by sliding caliper. Additional analyses included histological studies, histomorphometry, and computed tomography. SUBJECTS: Twenty-one 12-week-old female cats were divided into 3 groups, composed of 7 specimens. INTERVENTION: The control animals underwent periosteal elevation alone (group 1). The remaining animals underwent unilateral fronto-orbital craniotomy and subsequent reconstruction with orthotopic bone flap replacement (group 2) or HAC (group 3). RESULTS: All animals survived the study with no evidence of wound infection or implant failure. Gross morphological studies demonstrated excellent contour reconstruction in both experimental groups. Craniometric analysis detected 1 intergroup difference that consisted of a wider skull in group 3 on the reconstructed side. An intragroup difference in orbital height was also seen in group 3. Computed tomography demonstrated a solid appearance of the implant with obliteration of the left frontal sinus in group 3. Histological studies showed that HAC was osseointegrated to native bone, with areas of new bone interspersed throughout the implants. No significant inflammatory response or fibrous encapsulation was noted. Histomorphometry demonstrated that implants were replaced by osseous tissue in 44% to 50% of the animals within 5 months. CONCLUSION: Hydroxyapatite cement is safe and effective for craniofacial reconstruction in the developing feline and may be appropriate for similar applications in humans.

Oromandibular reconstruction using microvascular composite flaps: report of 210 cases.

OBJECTIVE: To review the experience of 1 microvascular surgeon during an 11-year period in performing 210 vascularized bone-containing free flaps for oromandibular reconstruction. DESIGN: Retrospective medical records review of patients who underwent primary and secondary oromandibular reconstruction with the use of vascularized bone free flaps. SETTING: Academic medical center. PATIENTS: A total of 201 patients underwent 210 composite free-flap reconstructions of the mandible for various disorders and with a range of bony and soft tissue defects. INTERVENTION: All patients underwent the microvascular transfer of vascularized bone flaps from the ilium, fibula, or scapula. In selected cases, 2 simultaneous free flaps were transferred to achieve an optimal bone and soft tissue reconstruction. Endosteal dental implants were used in 81 patients, with a total of 360 fixtures placed during these 11 years. MAIN OUTCOME MEASURES: The success of microvascular free tissue transfer, dental implant extrusion, and short- and long-term complications at the recipient and donor sites. RESULTS: Of the 210 mandibular reconstructions that were performed, 202 were successful in reestablishing mandibular continuity. Reexploration for vascular-related complications was done in 16 patients, 8 of whom were successfully treated, yielding an overall success rate of 96%. The overall success rate for endosteal dental implants was 92%. The implant success rate was 86% when the bone in which the fixtures were placed was irradiated postoperatively. The success rate was 64% in the 14 fixtures that were placed into previously irradiated bone. CONCLUSIONS: The success of the use of vascularized bone free flaps in restoring continuity to the mandible is clearly demonstrated in this series. There was an acceptable incidence of donor- and recipient-site complications that resulted in minimal long-term morbidity. The careful selection of a donor site(s) for oromandibular reconstruction allows for an optimal restoration of bony and soft tissue defects. Dental implants can be safely used in oromandibular reconstruction with a high level of success. Placing these implants during the initial surgery shortens the duration for achieving dental rehabilitation and enhances the success of the implants when postoperative radiotherapy is administered.

Hydroxyapatite cement, a smart biomaterial for craniofacial skeletal tissue engineering.

Craniofacial skeletal surgery continues to command special interest from patients and clinicians dealing with skeletal defects. Autologous bone grafts remain the standard treatment by which bone substitutes are compared. A continued interest in avoiding donor sites and realizing "off the shelf convenience" has fostered the use of biomaterial bone substitutes. The first generation of implant materials used for cranial reconstruction were not specifically designed for biomedical applications. Methylmethacrylate was adopted for cranial applications after use in implant fixation for hip arthroplasty by Charnley, The development of this material did not employ sophisticated implant evaluation and mainly focused on standard mechanical properties demonstrated on the benchtop.