The use of Teflon in orbital floor reconstruction following blunt facial trauma: a 20-year experience

A myriad of materials have been used for reestablishing continuity of the orbital floor following blunt facial trauma. Traditionally, autogenous grafts have been the material of choice for orbital floor reconstruction; however, alloplastic materials have gained popularity because of their availability and ease of use. A large clinical experience with long-term treatment results has never been reported for any substance used in orbital floor reconstruction. The purpose of this study was to review our long-term treatment results using Teflon for orbital floor reconstruction following blunt trauma, with emphasis on the incidence of infection, extrusion, and implant displacement. This report presents a 20-year review of 230 Teflon implants for reconstruction of traumatic orbital floor defects. With a mean follow-up period of 30 months, there was only one implant infection and no complications of extrusion or implant displacement. These findings support the use of Teflon as a safe and effective material for the reconstruction of orbital floor defects following blunt facial trauma.     

Validation of Bone Conversion in Osteoconductive and Osteoinductive Bone Substitutes

Bone reconstruction can be performed with an autogeneic graft from various donor regions. Osteoconductive and osteoinductive bone substitutes originate from substances of diverse chemical and morphological types and can have a synthetic or a biological derivation. Alongside autogeneic bone transplants and allogenic and xenogeneic bone implants, alloplastic bone replacements of synthetic or semi-synthetic origin are being used for defect reconstruction. In an animal model in rabbits five bone substitutes and one autogeneic graft were surgically incorporated into identical bone defects (10times 10 mm in size) in six anatomically defined regions of the skull. With scintigraphic and histological methods, the metabolic dynamics of the bone is examined as it reacts to the transplantation of autogeneic bone or to implanted bone replacement material. The different autogeneic, xenogeneic and alloplastic bone replacement materials can be differentiated according to the functional quality of the new tissue and the dynamics of the bone conversion thus induced. In the comparison of mineralized, osteoconductive bone subsitutes (TCP, HA, calcium carbonate ceramics) with demineralized, osteoinductive implants (DBM new, DBM old) and autogeneic bone grafts, the bone inducing matrices show the largest quantity of new bone formation, making possible a volume-constant reconstruction. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breast augmentation: choosing the optimal incision, implant, and pocket plane

A retrospective study of 220 patients was performed to review surgical design in breast augmentation. Three specific issues were studied: incision site, implant variables, and pocket plane selection. The influence of these three factors on aesthetic results in both primary and secondary cases was the focus of the analysis. No attempt was made to address long-term issues such as capsular contracture or saline implant deflation rates. In 77 primary augmentation patients and 80 unilateral augmentations for symmetry in breast reconstruction, there were the following untoward results: 11 revisions for unilateral malposition, change to a different implant shape, or change to a larger implant size; four deflations of saline implants requiring replacement; and four conversions of saline to silicone gel implants. In 63 secondary cases, there were two hematomas and two infections requiring implant removal and subsequent replacement. Operative technique in breast augmentation is described, as are recommendations for each of the options associated with the three variables studied.     

Experimental hydroxyapatite cement cranioplasty.

Hydroxyapatite cement is a calcium phosphate-based material that when mixed with water forms a dense paste that sets within 15 minutes and isothermically converts in vivo to a microporous hydroxyapatite implant. This cement was used to reconstruct bilateral 2.5-cm-diameter full-thickness critical-sized parietal skull defects in six cats. One side was reconstructed with 100 percent hydroxyapatite cement, and the other with a mixture of 50 percent hydroxyapatite cement and 50 percent ground autogenous bone by weight. These animals were sacrificed at 6 and 12 months after implantation. Positive and negative controls also were prepared. The anatomic contour of the soft tissue overlying all hydroxyapatite cement implants was well maintained, there were no wound infections or structural failures, and the implants were well tolerated histologically. None of the negative (unreconstructed) control defects was completely filled with repair bone, and all positive (methyl methacrylate) controls demonstrated foreign-body giant-cell formation and fibrous encapsulation of the implants. Examination of decalcified and undecalcified sections revealed progressive but variable replacement of the cement by new bone and soft tissue without a change in the shape or volume of the hydroxyapatite cement-reconstructed areas. New bone comprised 77.3 and 64.7 percent of the tissue replacing the hydroxyapatite cement and hydroxyapatite cement-bone implants, respectively. Replacement of the hydroxyapatite cement implants by new bone is postulated to occur by a combination of osteoconduction and implant resorption. These results indicate that further experimental research leading to the possible application of hydroxyapatite cement for full-thickness calvarial defect reconstruction in humans is warranted.     

Comparison of the biological activities of high-density porous polyethylene implants and oxidized regenerated cellulose-wrapped diced cartilage grafts

The use of alloplastic materials in plastic surgery has become more extensive with advancement of autogenous-tissue reconstruction techniques for the repair of defects, tissue augmentation, and the stabilization of bones. An ideal alloplastic material should be nonallergenic, noncarcinogenic, sterilizable, and easy to shape and should not cause rejection. Alloplastic material used for tissue augmentation should have a low rate of resorption and distortion. High-density porous polyethylene implants (Medpor) have been used widely and successfully for tissue augmentation. The Turkish Delight is a material composed of diced cartilage grafts wrapped in oxidized regenerated cellulose (Surgicel). Its indications are similar to those of the Medpor implant, and an additional donor site is usually not needed. Both materials are used in the same anatomical locations, especially for augmentation. Therefore, the authors evaluated the long-term stability of and suitable anatomical sites for these materials. Medpor implants or Turkish Delights were placed subperiosteally or subfascially in 10 young rabbits, and the resultant changes were evaluated 16 weeks after the operation by macroscopy and histopathology. Changes in projections were measured with an ocular micrometer. Medpor implants were neither resorbed nor distorted when placed subperiosteally or subfascially, and were highly stabilized by the surrounding tissues. Turkish Delight also enabled tissue augmentation, but had a significantly higher rate of resorption compared with the Medpor implant and was loosely bound to the surrounding tissue. The Turkish Delight was less resorbed and better fixed to adjacent tissues when placed subperiosteally than when placed subfascially.     

Frontal cranioplasty: risk factors and choice of cranial vault reconstructive material

A study of patients with large cranial defects involving the frontal bone, frontal sinus, nose, and orbit does not support the contention that there is a clear superiority of reconstructive material despite a history of previous bone infection. No patient with an isolated cranial reconstruction experienced an infection despite location in the area of the frontal sinus or the use of acrylic material. All patients experiencing infection underwent simultaneous reconstruction of the frontal cranium and nose and three- or four-wall reconstruction of the orbit, where the frontal sinus had previously been eliminated and where a previous bone infection had been present. Risk factors associated with cranioplasty were timing (p = 0.001) and cranial vault reconstruction in communication with previously infected ethmoid sinuses and the nose (p = 0.03). A history of previous bone infection suggests increased risk (p = 0.15). The choice of reconstructive material was not significant, although acrylic cranioplasties did not experience the complications expected from a review of the literature.     

Engineered cartilage covered ear implants for auricular cartilage reconstruction

Cartilage tissues are often required for auricular tissue reconstruction. Currently, alloplastic ear-shaped medical implants composed of silicon and polyethylene are being used clinically. However, the use of these implants is often associated with complications, including inflammation, infection, erosion, and dislodgement. To overcome these limitations, we propose a system in which tissue-engineered cartilage serves as a shell that entirely covers the alloplastic implants. This study investigated whether cartilage tissue, engineered with chondrocytes and a fibrin hydrogel, would provide adequate coverage of a commercially used medical implant. To demonstrate the in vivo stability of cell-fibrin constructs, we tested variations of fibrinogen and thrombin concentration as well as cell density. After implantation, the retrieved engineered cartilage tissue was evaluated by histo- and immunohistochemical, biochemical, and mechanical analyses. Histomorphological evaluations consistently showed cartilage formation over the medical implants with the maintenance of dimensional stability. An initial cell density was determined that is critical for the production of matrix components such as glycosaminoglycans (GAG), elastin, type II collagen, and for mechanical strength. This study shows that engineered cartilage tissues are able to serve as a shell that entirely covers the medical implant, which may minimize the morbidity associated with implant dislodgement.     

Permanent lip augmentation employing polytetrafluoroethylene grafts.

There is a paucity of literature regarding aesthetic enhancement of the lips. This is due to the lack of reliable techniques employing autogenous tissue and the reluctance on the part of surgeons to use an alloplastic implant in this anatomic region, which is superficial, subject to trauma, and must conform to innumerable geometric shapes. The ideal lip augmentation procedure should provide for a predictable, permanent enlargement without visible scars or donor-site deformity, can be customized to the particular patient's anatomy, and can be reversed if so desired. A series of 21 alloplastic lip implants employing polytetrafluoroethylene with a mean follow-up of 14.33 months is presented. The overall complication rate was 9.52 percent. Permanent lip augmentation can be achieved with alloplastic sheet grafts of polytetrafluoroethylene in a safe and predictable fashion. Stiffness of the lips develops with progressive thickness of the grafts. Grafts exceeding 3 mm in thickness should be avoided.     

Patellar mechanics during simulated kneeling in the natural and implanted knee

Kneeling is required during daily living for many patients after total knee replacement (TKR), yet many patients have reported that they cannot kneel due to pain, or avoid kneeling due to discomfort, which critically impacts quality of life and perceived success of the TKR procedure. The objective of this study was to evaluate the effect of component design on patellofemoral (PF) mechanics during a kneeling activity. A computational model to predict natural and implanted PF kinematics and bone strains after kneeling was developed and kinematics were validated with experimental cadaveric studies. PF joint kinematics and patellar bone strains were compared for implants with dome, medialized dome, and anatomic components. Due to the less conforming nature of the designs, change in sagittal plane tilt as a result of kneeling at 90° knee flexion was approximately twice as large for the medialized-dome and dome implants as the natural case or anatomic implant, which may result in additional stretching of the quadriceps. All implanted cases resulted in substantial increases in bone strains compared with the natural knee, but increased strains in different regions. The anatomic patella demonstrated increased strains inferiorly, while the dome and medialized dome showed increases centrally. An understanding of the effect of implant design on patellar mechanics during kneeling may ultimately provide guidance to component designs that reduces the likelihood of knee pain and patellar fracture during kneeling.     

Osseointegrated alloplastic ear reconstruction with the implant-carrying plate system in children

Osseointegration biotechnology has revolutionized ear prosthetic retention, and the benefits of osseointegrated alloplastic ear reconstruction have been well documented. The aim of this study is to present the authors' clinical experience with the implant-carrying plate system (EPITEC System) in children. For 3.5 years, 14 microtia patients (13 boys and one girl, ages 6 to 16 years) were treated with osseointegrated prosthetic ear reconstruction. A total of 30 titanium implant posts of the system were used; one of the patients had bilateral defects. Implant posts were inserted into a three-dimensional carrier plate, which was fixed by means of screws to the mastoid. All patients were operated on using a one-stage procedure allowing 2 to 3 months for osseointegration, followed by fabrication of the ear prostheses. After follow-up, which varied from 6 to 42 months for each patient, all implants that could be monitored were found to be stable. A total of 21 implant posts remained free from potentially dangerous skin reactions. The soft tissues around five of the implant posts in three patients were hypertrophied. One patient was lost to follow-up. The results suggest that the implant-carrying plate system offers several advantages in children: (1) Location of the implants is independent of the recipient bone available; (2) no apparent submergence is evident; (3) additional anchoring is achieved by newly formed bone growing over and covering the connecting bars of the three-dimensional carrier plate, which is only 1 mm thick; and (4) osseointegration is highly successful. Because of the limited number of cases represented in this article, along with a rather limited observation period, this study is preliminary. For a final evaluation, a longer observation time is needed. Despite this, the authors believe that a one-stage procedure with the system in the mastoid process in children can be recommended.     

Maxillary reconstruction with a fibula osteoseptocutaneous free flap and simultaneous insertion of osseointegrated dental implants

The fibula osteoseptocutaneous flap is a good option for reconstruction of three-dimensional composite maxillary defects. This flap provides both bone and soft-tissue reconstruction and allows osseointegrated dental implantation, either simultaneously or in a second-stage procedure. Simultaneous placement of osseointegrated dental implants reduces operative sessions and allows faster oral rehabilitation for properly selected patients. The defects may result from trauma or resection of benign tumors or low-grade malignancies. Between August of 1999 and July of 2001, three patients underwent maxillary reconstruction with the fibula osteoseptocutaneous flap and simultaneous osseointegrated dental implants. The cause of the defect was trauma in two cases and resection of an adenoid cystic carcinoma in the other. The mean length of the fibula used for bony reconstruction was 4.7 cm. One osteotomy was performed in one case and no osteotomy was necessary in the other two. Skin islands of 8 x 2.5 cm and 16 x 3.5 cm were used for two patients. For the other patient, a double skin island was used for both nasal (6 x 4 cm) and oral (6 x 5 cm) reconstructions. Two osseointegrated implants were inserted into the fibular bone for each patient. Six months after the first-stage procedure, palatal rotation flaps or mucosa grafts were used to cover the exposed implant necks and prepare the implants for prostheses. One month after the second-stage procedure, prostheses were placed. An implant-supported prosthesis was used for one patient and implant/tissue-supported prostheses were used for the others. At a mean follow-up time of 30 months (range, 16 to 38 months), all patients were able to use the dental prosthesis for chewing (beginning 6 weeks after the final procedure) and all patients were satisfied with the cosmetic results.     

Efficiency of polylactide/polyglycolide copolymers bone replacements in bone defects healing measured by densitometry

Healing of bone defects is the most frequent cause of failure in surgical treatments of an odontogenic ostitic processes. The aim of this study was to determine successfulness in healing of bone defects after implantation of alloplastic co-polymer-polyglycol bone implant. A group of 45 cases with periradicular ostitic processes were examined. The densitometric measurements were taken from radiovisiographic dental x-ray images. Patients were observed throughout a period of one year. The results obtained were analyzed and presented graphically. Thirty-eight patients (84%) were treated successfully, and seven patients (16%) showed unsuccessful healing of the bone defects. The results obtained indicate that polyglycol copolymer bone implants can be successfully used in a treatment of odontogenically caused bone defects. Their fundamental advantage is a slow biodegradation, which ensures a more suitable area for the apposition of a new bone in the defect, simple application in clinical work and the possibility of a mutual combination of all three available forms.     

Osteochondral reconstruction of a non-weight-bearing joint using a high-density porous polyethylene implant

Currently, there is no reliable reconstructive modality allowing anatomic resurfacing of traumatic digital osteochondral articular defects. The purpose of the present study is to demonstrate the utility of Medpor, a high-density porous polyethylene (HDPP) scaffold biomaterial that can (1) be readily contoured to fit any joint defect, (2) permit stable internal fixation, and (3) permit osteocyte and chondrocyte ingrowth and subsequent articular cartilage resurfacing necessary to restore joint congruity. HDPP has gained wide acceptance for use in craniofacial and skeletal reconstruction and augmentation. An avian non-weight-bearing joint model was designed to study the role of the HDPP implant in small joint reconstruction. An osteochondral defect was created with a 5-mm circular punch in the humeral articular surface of both glenohumeral joints of 32 adult White Leghorn chickens. In each animal, one defect was press-fitted with a correspondingly sized HDPP implant (HDPP implant group); the contralateral defect was filled with the original osteochondral plug (isograft group) or left unrepaired (control group). At 2 weeks, and 1, 3, and 6 months,joints from each group were harvested and evaluated. Over the 6-month study period, joints in the control group demonstrated healing with dense collagenous scar tissue leaving residual defects at the articular surfaces and significant degenerative disease of the glenohumeral joints radiographically. Joints in the isograft group demonstrated near-complete resorption with some preservation of the cartilaginous cap but overall depression of the articular surface and significant degenerative joint disease. Joints in the HDPP implant group demonstrated stable fixation by highly mineralized bony trabecular ingrowth, preservation of the articular contour of the humeral head, and no evidence of significant degenerative joint disease. These findings indicate a potential role for this high-density porous polyethylene implant in the reconstruction of small joint articular and osseous defects.     

Biomedical application of commercial polymers and novel polyisobutylene-based thermoplastic elastomers for soft tissue replacement

Novel polyisobutylene-based thermoplastic elastomers are introduced as prospective implant materials for soft tissue replacement and reconstruction. In comparison, poly(ethylene terephthalate) (PET), poly(tetrafluoroethylene) (PTFE), polypropylene (PP), polyurethanes (PU), and silicones are outlined from well-established implant history as being relatively inert and biocompatible biomaterials for soft tissue replacement, especially in vascular grafts and breast implants. Some general considerations for the design and development of polymers for soft tissue replacement are reviewed from the viewpoint of material science and engineering, with special attention to synthetic materials used in vascular grafts and breast implants.     

Rigid fixation of internal orbital fractures

When large portions of the internal orbit are destroyed (two to four walls), standard bone-grafting techniques for immediate and late orbital reconstruction may not yield predictable eye position. Critical bone support is most often deficient inferomedially. CT analysis of orbital volume in cases where eye position was unsatisfactory reveals that displacement of bone grafts is one mechanism of the unsatisfactory result. Other mechanisms include undercorrection and bone-graft resorption. In order to minimize postoperative bone-graft displacement, titanium implants were used to span large defects in the internal orbit to provide a platform for bone-graft support. Twenty-six implants were placed in immediate and 12 were placed in late orbital reconstructions. More reliable bone-graft position resulted. Two late infections have occurred resulting in implant removal in a 3-year period.     

Treatment of large complex cranial bone defects by using hydroxyapatite ceramic implants

Hydroxyapatite ceramic implants were used in the reconstruction of very large and complex-form cranial bone defects in nine patients. The bone defects were the result of craniectomy after infections and other complications such as severe brain edema, after neurosurgery, and as a result of trauma, subdural hemorrhage, and surgery for brain tumor. The size, shape, and curvature of the hydroxyapatite ceramic implants were determined based on high-precision, full-scale models fabricated through a laser lithographic molding method by using computed tomographic data. The use of this method allowed the fabrication of hydroxyapatite ceramic implants of shapes that accurately matched the area of bone defect, allowing for a minimum of adjustment during the operation even with a complex-form implantation. Not only were good cranial contour reconstructed and aesthetically satisfactory results obtained in the cases treated by incorporating this series of techniques, but neurologic conditions present in some cases were also improved to some extent. The postoperative course has been steady for all nine patients, with no blood transfusions required during or after the operations and no implants requiring removal because of infection or other postoperative complications. The average length of postoperative hospitalization for the nine cases was 11.7 days, remarkably short considering the clinical conditions.     

Proliferation rate of human osteoblast-like cells on alloplastic biomaterials and their clinical application for the transnasal duraplasty procedure

The possibility of transmission of slow virus infection (HIV) and Creutzfeld-Jakob disease by cadaveric dura implants makes it necessary to find synthetic, absorbable materials for the reconstruction of the dura mater. Various procedures with autologous or alloplastic material are described. Four commercially available biomaterials were choosen to study the proliferation rate and the biocompatibility of human osteoblast-like cells (HOB-like cells) on 2- dimensional material by biochemical analysis. With a proliferation assay, the viability and the proliferation capacity of osteoblast-like cells were evaluated. A clinical trial was added to study resorbable fleece as one of the previously tested biomaterial in a small patient group (8 patients) to close anterior cranial fossa dura defects. The results of the proliferation assay showed the highest proliferation rate of HOB-like cells on resorbable fleece. All patients in our clinical trial with anterior cranial fossa dura defects were successfully treated with resorbable fleece. There was no evidence for persisting cerebrospinal fluid rhinorrhea or foreign body reaction after the period of wound healing. The present study demonstrated an excellent biocompatibility of resorbable fleece. The vicryl fleece is an alternative alloplastic material for endonasal closure of defined substantial defects of the dura with cerebrospinal fluid.     

The coincidence of TRAM flaps and prostheses in the setting of breast reconstruction

It is well known that transverse rectus abdominis myocutaneous (TRAM) flaps can be used to replace unsatisfactory prosthetic breast reconstructions; however, little has been written about the scope of breast implant use in TRAM flap patients. In this study, to ascertain the range of such therapeutic options, their frequency, and their clinical outcomes, the authors retrospectively reviewed the senior author's breast reconstruction experience from 1989 to 2000 with patients in whom both a TRAM flap and an implant were used for breast reconstruction. The authors examined the surgical indications, body habitus, bra size, chest wall irradiation history, flap type, implant type, complications, and outcomes for those patients with TRAM flap and breast implant combinations.Thirty-two women who had 50 (various) combinations of a TRAM flap and a breast implant were identified. There were more clinical scenarios than patients because many of the women had multiple scenarios. The 50 combination scenarios were then divided into six groups. Group I consisted of 14 patients who had elective prostheses placed beneath simultaneous TRAM flaps; group II consisted of 10 patients who had TRAM flaps with contralateral prosthetic reconstruction (in which two implants were received before the TRAM flaps, five implants were received simultaneously with the TRAM flaps, and three implants were received after the TRAM flaps); group III consisted of eight patients who had contralateral augmentation in addition to their TRAM flaps; group IV consisted of 11 patients who had TRAM flaps that were used to cover or replace previous prosthetic reconstructions; group V consisted of four patients in whom prostheses were used to augment or improve previous TRAM flap reconstructions; and group VI consisted of three patients who required prostheses to either reconstruct or salvage total or near-total TRAM flap failures. A broad range of implant types was used, although anatomic saline implants predominated. Forty-one percent of the patients in the review had undergone irradiation during the course of their treatment for breast cancer. Eight of the 32 patients experienced a total of twelve complications, four of which were related to the implants and eight of which involved the TRAM flaps and abdominal donor sites.Although complex, the wide variety of potential TRAM flap/breast implant combinations can be useful for patients with challenging reconstructive scenarios, particularly those that involve radiation therapy. In the group of patients reviewed by the authors, TRAM flaps were most often used in successful partnership either on the same side as or opposite to an implant reconstruction. A TRAM flap was used to salvage or replace an unsatisfactory implant reconstruction in less than a third of the patients. From a risk point of view, implants used opposite a TRAM flap reconstruction had a lower incidence of complication than did implants used beneath TRAM flaps.     

Reconstruction of an extreme frontal and frontobasal defect by microvascular tissue transfer and a prefabricated titanium implant

A 30-year-old man was referred to us with an extreme frontal and frontobasal defect from a motorbike accident 12 years before. Multiple attempts at frontal and frontobasal revision and reconstruction had been performed over the years, with several episodes of meningitis. Reconstruction was planned in two steps. First, a revision of the anterior skull base with mobilization of meningeal adhesions and duraplasty, removal of infected masses of polymethylmethacrylate out of the upper ethmoid sinuses, and coverage with a deepithelialized latissimus dorsi free flap were performed. In the second step 3 months later, aesthetic forehead reconstruction was achieved with a pre-fabricated individual titanium implant. The predictable result of this two-step reconstruction was very pleasing. Safe separation of the cranial cavity from the upper airways was essential, requiring free tissue transfer in this case, and is a prerequisite for any alloplastic forehead reconstruction. Timing of the two-step procedure, including the CT data acquisition; handling of soft tissues, bone, and foreign material; and construction details of the implant demonstrate the necessary complex management of this, the most difficult case of the 88 applications of the new computer aided design and manufacturing technique thus far. Even the most elaborate computer aided preparation cannot be successful without consideration of established surgical principles.     

Self-reported symptoms among women after cosmetic breast implant and breast reduction surgery

A retrospective cohort study was performed in Sweden to evaluate the possibility that an individual symptom or constellation of illness symptoms related to silicone occurs in women after breast implant surgery. A random sample (n = 2500) of all women in the Swedish national implant registry who underwent breast augmentation surgery with alloplastic breast implants during the years 1965 through 1993 was compared with a sample (n = 3500) of women who underwent breast reduction surgery during the same period, frequency matched to the implant patients for age and calendar year at the time of surgery. In total, 65 percent of the breast implant patients (n = 1546) and 72 percent of the breast reduction patients (n = 2496) completed a self-administered questionnaire covering 28 rheumatologic and other symptoms and lifestyle and demographic factors. Practically all of the 28 symptoms inquired about were reported more often by women in the breast implant cohort, with 16 (57 percent) significantly more common in breast implant recipients. In contrast, few significant differences or consistent patterns were observed in the length of time since the implant and in the type (silicone or saline) or volume of the implant. Although women with breast implants report a multitude of symptoms more often than women who have breast reduction surgery, the lack of specificity and absence of dose-response relationships suggest that the excess of reported symptoms is not causally related to cosmetic implants.