Self-reinforced polyglycolic acid membrane: a bioresorbable material for orbital floor repair. Initial clinical report

Functional Scaffolds for Bone Tissue Regeneration: A Comprehensive Review of Materials, Methods, and Future Directions

Bone tissue regeneration is a rapidly evolving field aimed at the development of biocompatible materials and devices, such as scaffolds, to treat diseased and damaged osseous tissue. Functional scaffolds maintain structural integrity and provide mechanical support at the defect site during the healing process, while simultaneously enabling or improving regeneration through amplified cellular cues between the scaffold and native tissues. Ample research on functionalization has been conducted to improve scaffold-host tissue interaction, including fabrication techniques, biomaterial selection, scaffold surface modifications, integration of bioactive molecular additives, and post-processing modifications. Each of these methods plays a crucial role in enabling scaffolds to not only support but actively participate in the healing and regeneration process in bone and joint surgery. This review provides a state-of-the-art, comprehensive overview of the functionalization of scaffold-based strategies used in tissue engineering, specifically for bone regeneration. Critical issues and obstacles are highlighted, applications and advances are described, and future directions are identified.

Resorbable Implants for Orbital Fractures: A Systematic Review

BACKGROUND

Orbital fractures are one of the most common sequelae of facial trauma.

OBJECTIVE

The objective of this study was to summarize published data for resorbable implants in orbital reconstruction, including polymer composition, degradation characteristics, osteoconductivity, and complications such as enophthalmos, diplopia, and peri-implant inflammation. A literature search of the National Library of Medicine was performed via PubMed using the keyword resorbable orbital implant. A total of 27 studies were reviewed. Strength of data was assessed according to the Oxford Centre criteria.

RESULTS

Most commercially available implants provide adequate tensile strength for up to 6 months (with the exception of polydioxanone, which loses strength within 1 month, and poly(D,L-lactide) within 3 months). This is sufficient for the isolated orbital floor or medial wall (tensile strength, ~300 MPa) but insufficient for reconstruction of load-bearing areas (eg, the inferior orbital rim with tensile strength of ~1.2 GPa). Thicker products (>1 mm) have increased risk for delayed inflammation than thinner products. Postoperative complications including delayed inflammation (0%-9%), eyelid malposition (0%-5%), enophthalmos (5%-16%), diplopia (0%-16%), infection (0%-2%), and infraorbital nerve hypesthesia (2%-18%) are variably distributed across implants with several notable exceptions: poly(L-lactide) has an increased risk of delayed inflammation, and polydioxanone has a risk of delayed enophthalmos and hematoma.

CONCLUSIONS

Resorbable implants are suitable for isolated medial wall or floor fractures with intact bony buttresses and function as a barrier rather than a load-bearing support.

* Engineering Membranes for Bone Regeneration

This review is focused on the use of membranes for the specific application of bone regeneration. The first section focuses on the relevance of membranes in this context and what are the specifications that they should possess to improve the regeneration of bone. Afterward, several techniques to engineer bone membranes by using "bulk"-like methods are discussed, where different parameters to induce bone formation are disclosed in a way to have desirable structural and functional properties. Subsequently, the production of nanostructured membranes using a bottom-up approach is discussed by highlighting the main advances in the field of bone regeneration. Primordial importance is given to the promotion of osteoconductive and osteoinductive capability during the membrane design. Whenever possible, the films prepared using different techniques are compared in terms of handability, bone guiding ability, osteoinductivity, adequate mechanical properties, or biodegradability. A last chapter contemplates membranes only composed by cells, disclosing their potential to regenerate bone.

Efficacy of Resorbable Plates for Reduction and Stabilization of Laryngeal Fractures

We evaluated the efficacy of resorbable reconstruction plates (polylactic acid copolymer) for the open reduction and stabilization of displaced laryngeal fractures. Both MacroPore and Leibinger reconstruction plates were used with equal ease of application in 3 adult male patients. We found the plating system to be especially effective for the reduction of comminuted cricoid fractures. Adequate skeletal stabilization allowed early resumption of phonatory and respiratory function without long-term intraluminal stenting for skeletal support. No complications of hematoma, seroma, or infection were experienced. Resorbable plates appear to be relatively safe and useful for internal fixation of both cartilaginous and ossified parts of the larynx, allowing rapid rehabilitation and return of function.

Biodegradable Materials for Bone Repair and Tissue Engineering Applications

This review discusses and summarizes the recent developments and advances in the use of biodegradable materials for bone repair purposes. The choice between using degradable and non-degradable devices for orthopedic and maxillofacial applications must be carefully weighed. Traditional biodegradable devices for osteosynthesis have been successful in low or mild load bearing applications. However, continuing research and recent developments in the field of material science has resulted in development of biomaterials with improved strength and mechanical properties. For this purpose, biodegradable materials, including polymers, ceramics and magnesium alloys have attracted much attention for osteologic repair and applications. The next generation of biodegradable materials would benefit from recent knowledge gained regarding cell material interactions, with better control of interfacing between the material and the surrounding bone tissue. The next generations of biodegradable materials for bone repair and regeneration applications require better control of interfacing between the material and the surrounding bone tissue. Also, the mechanical properties and degradation/resorption profiles of these materials require further improvement to broaden their use and achieve better clinical results.

Reconstruction of small orbital floor fractures with resorbable collagen membranes

Orbital floor fractures are the most common facial fractures. The goals of orbital floor fracture repair are to free incarcerated or prolapsed orbital tissue from the fracture defect and to span the defect with an implant to restore the correct anatomy of the orbital floor and the pretrauma orbital volume. No consensus exists on the choice of implants to be used for orbital floor reconstruction, and several implant materials are available.Our study intended to evaluate, for the first time, the effectiveness and complications related to the use of a resorbable collagen membrane in the reconstruction of small pure blow-out fractures. From October 2008 to November 2010, 23 patients who underwent reconstruction of the orbital floor using a resorbable collagen membrane following fracture were included in this study. At the 6-month follow-up, only 2 patients (9%) reported postoperative complications secondary to the operative procedure (surgical approach, orbital floor dissection), but these were not directly related to the use of the membrane. In 12 cases, a computed tomography scan revealed new bone formation beneath the membrane.On the basis of this data, we believe that the use of a resorbable collagen membrane is a safe and effective alternative for reconstruction of small (<3 cm(2)) pure orbital floor fractures.

Biomaterials for repair of orbital floor blowout fractures: a systematic review

PURPOSE

To evaluate the reported use and outcomes of implant materials used for the restoration of post-traumatic orbital floor defects in adults.

MATERIALS AND METHODS

A systematic search of the English literature was performed in the databases of PubMed, Cochrane Library, and EMBASE. The study selection process was adapted from the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, and 55 articles complied with the study inclusion criteria. The primary outcome measures were diplopia, enophthalmos, graft extrusion/displacement, and infection related to the graft material. The secondary outcome measures were infraorbital paresthesia, orbital dystopia, orbital soft tissue entrapment, and donor-site complications.

RESULTS

Of 55 articles, 41 (74.5%) evaluated were retrospective case series, 9 (16.4%) were retrospective case-control studies, 3 (5.5%) were controlled trials, and 2 (3.6%) were prospective case series. Autogenous graft materials were predominantly used in 19 studies, alloplastic materials were used in 33 studies, and the remaining 3 articles reported on allogeneic materials. Overall, 19 different types of implant materials were used in 2,483 patients. Of 827 patients with diplopia before surgery, 151 (18.3%) had diplopia postoperatively. Of 449 patients with enophthalmos before surgery, 134 (29.8%) had enophthalmos postoperatively. Only 2 patients (0.1%) and 14 patients (0.6%) had graft extrusion/displacement and infection related to the graft material, respectively; alloplastic biomaterials were used in all of these cases.

CONCLUSIONS

All graft materials used were successful to variable degrees because all studies reported improvement in terms of the recorded outcome measures. A guideline for choice of implant material based on defect size was developed.

Biomaterials and implants for orbital floor repair

Treatment of orbital floor fractures and defects is often a complex issue. Repair of these injuries essentially aims to restore the continuity of the orbital floor and to provide an adequate support to the orbital content. Several materials and implants have been proposed over the years for orbital floor reconstruction, in the hope of achieving the best clinical outcome for the patient. Autografts have been traditionally considered as the "gold standard" choice due to the absence of an adverse immunological response, but they are available in limited amounts and carry the need for extra surgery. In order to overcome the drawbacks related to autografts, researchers' and surgeons' attention has been progressively attracted by alloplastic materials, which can be commercially produced and easily tailored to fit a wide range of specific clinical needs. In this review the advantages and limitations of the various biomaterials proposed and tested for orbital floor repair are critically examined and discussed. Criteria and guidelines for optimal material/implant choice, as well as future research directions, are also presented, in an attempt to understand whether an ideal biomaterial already exists or a truly functional implant will eventually materialise in the next few years.

Effectiveness of a nasoseptal cartilaginous graft for repairing traumatic fractures of the inferior orbital wall

The goals of reconstruction after an orbital fracture are to restore the continuity of the floor, provide support for the orbital contents, and prevent fibrosis of the soft tissues. Nasoseptal cartilage is an easily accessible, abundant, and autogenous source that supports the orbital floor and gives minimal donor site morbidity. We evaluated the effectiveness of nasoseptal cartilage for repairing traumatic defects of the orbital floor. Autogenous nasoseptal cartilage was used in 20 patients. Presence or absence of diplopia, enophthalmos, paraesthesia of the infraorbital nerve, dystopia, range of covering of the defect by nasoseptal cartilage, complications at the recipient and donor sites, resorption of the graft, and ocular mobility disorders were recorded. Entrapment of orbital tissues, a large orbital defect (more than 50% of orbital floor or more than 8mm), or defects of the orbital floor with involvement of other fractures of the zygomaticofrontal complex are indications for exploration of the orbit. In one case after 24 months, the surgical field was explored for direct evaluation of the efficacy of the graft. All patients were treated successfully by restoration of the continuity of the orbital floor. Six months to 2 years follow up showed only one patient with postoperative enophthalmos. There was no donor site morbidity, and no grafts became infected or extruded. The nasoseptal graft was completely covered with underlying tissue. Nasoseptal cartilage is readily accessible autogenous tissue that should be considered when an autogenous graft is needed for reconstruction of a defect of the orbital floor.

The impact of polyglycolide membrane on a tendon after surgical rejoining. A histological and histomorphometric analysis in rabbits

Tissue response to self-reinforced polyglycolide (SR-PGA) membranes surrounding rejoined rabbit tendons was compared with tissue response to nonenveloped rejoined tendons, with special focus on scar formation and SR-PGA membrane biodegradation process. Both hind legs of 20 skeletally mature rabbits were operated on by transecting the plantaris longus tendons and rejoining the ends with sutures. The right side seams were enveloped with bioabsorbable SR-PGA membranes, while the left sides served as noncovered controls. The follow-up times were 3, 6, 12, and 24 weeks. Scar formation and tissue response to membranes were studied by histological and histomorphometric analysis. Tendon regeneration was most active at 3 weeks. Capillary formation was more prominent in specimens with shorter follow-up times. Membrane degradation induced an inflammatory reaction observed at all follow-up time points. Under polarizing microscopy, birefringent SR-PGA material was seen to vanish almost completely by 24 weeks. SR-PGA membranes had no specific effect on scar formation and there were no differences in the reunion process of the transected tendon ends between the SR-PGA membrane groups and the controls. Inflammatory cells in the SR-PGA membrane groups reflected a tissue reaction to the membrane. When placed in soft tissues, SR-PGA membranes degraded almost completely within 24 weeks.

Reconstruction of Internal Orbital Wall Fracture with Iliac Crest Free Bone Graft: Clinical, Computed Tomography, and Magnetic Resonance Imaging Follow-Up Study

BACKGROUND

The purpose of this study was to clinically and radiologically assess the outcome of internal orbital reconstruction with an iliac bone graft.

METHODS

Twenty-four consecutive patients with unilateral orbital wall fractures were enrolled in this prospective study. A medial cortical wall from the anterior ilium was used for reconstruction. At each follow-up visit, globe posture, diplopia, and eye movements were assessed. Coronal and sagittal computed tomography and magnetic resonance imaging were used to observe graft posture, bone defects, and intraorbital soft-tissue changes.

RESULTS

Most fractures (46 percent) were pure orbital floor fractures. The mean follow-up was 7.8 months. One patient with medial wall and floor fractures required reoperation because of insufficient bone graft. At the last follow-up, this was the only patient (4 percent) with both enophthalmos (2 mm) and hypophthalmos (3 mm). Five patients (21 percent) had hypophthalmos (> 1 mm) at the end of the study. Resorption and remodeling were detected in all grafts, but no grafts were totally resorbed. Sagittal or coronal bone graft postures were assessed as good in 18 orbits (75 percent). Bone defects (> 10 mm) at reconstructed areas were detected in 13 orbits (54 percent). Scar tissue was observed only in three reconstructed orbits (13 percent). Diplopia in central field of vision was registered in seven patients preoperatively but in none at the end of the study.

CONCLUSIONS

The resorption rate was high, but most of it was advantageous remodeling. Overall outcome was good. Secondary operations led to poor outcomes. Thin computed tomography and magnetic resonance imaging sections (< or = 2 mm) are needed to evaluate accurately bone graft placement and posture and orbital volume.

A Comparative Study of 2 Implants Used to Repair Inferior Orbital Wall Bony Defects: Autogenous Bone Graft Versus Bioresorbable Poly-L/DL-Lactide [P(L/DL)LA 70/30] Plate

PURPOSE

The purpose of this study was to compare our clinical findings on the use of autogenous bone grafts and bioresorbable poly-L/DL-Lactide [P(L/DL)LA 70/30] implants to repair inferior orbital wall defects.

PATIENTS AND METHODS

Thirty-nine patients who suffered orbital blow-out fractures with >or=2 cm2 bony defect in the inferior orbital wall took part in the study. Each inferior orbital wall was reconstructed using either an autogenous bone graft or a triangle form plate of P(L/DL)LA 70/30. Computed tomography scans were taken before the operation and at 2 and 36 weeks postoperatively. To describe the distribution of complications and facilitate statistical analysis, we categorized our findings into diplopia, enophthalmos, numbness, gaze restrictions, size of bony defect after treatment, bone growth, and implant resorption. A comparative study was carried out using chi2 test and the Fisher exact test. We considered P < .05 to be statistically significant.

RESULTS

The clinical outcome was excellent in 19 of the 24 (79%) cases treated with autogenous bone grafts and in 13 of the 15 (87%) cases treated with P(L/DL)LA 70/30. No statistically significant differences were found between the 2 groups in overall type or number of complications. The most frequent type of complication found in both groups was enophthalmos, with 5 cases (bone graft, 3; P(L/DL)LA plates, 2). Diplopia was the second most frequent type of complication; however, both complications caused no need for the removal of the implants in either group.

CONCLUSION

Autogenous bone grafts and P(L/DL)LA 70/30 implant plates do not present statistically significant differences in the parameters studied. Taking into account the availability and the advantages of P(L/DL)LA 70/30 implants when compared with autogenous bone grafts, our results allow us to conclude that there is no compromise regarding successful bridging of orbital floor defects using biodegradable P(L/DL)LA 70/30 osteosyntheses.

Bioresorbable poly-L/DL-lactide (P[L/DL]LA 70/30) plates are reliable for repairing large inferior orbital wall bony defects: a pilot study

PURPOSE

The purpose of this study was to share our clinical experience on the use of bioresorbable poly-L/DL-lactide implants (P[L/DL]LA) 70/30 (PolyMax; Synthes, Oberdorf, Switzerland) to repair, large (> or =2 cm2), inferior orbital wall defects and to evaluate whether P(L/DL)LA 70/30 implants adequately support the orbital soft tissue contents.

PATIENTS AND METHODS

Thirteen patients who suffered orbital blowout fractures, with > or =2 cm2 bony defects in the inferior orbital wall, took part in the study. The inferior orbital wall was explored via subconjunctival approach. After repositioning of orbital content, each inferior orbital wall was reconstructed using a round plate of P(L/DL)LA 70/30. Computed tomography and magnetic resonance imaging coronal sections were undertaken before the operation and 2 and 36 weeks postoperatively.

RESULTS

The magnetic resonance imaging studies showed no abnormal tissue foreign body reactions in the orbital region. The material showed adequate strength to stabilize bone segments during the critical period of bone healing. The bone healing seems to take place along the bone fragments. The clinical outcome was excellent in 11 of the 13 cases (85%). At the end of the study, only one patient had mild enophthalmos.

CONCLUSIONS

Bioresorbable P(L/DL)LA 70/30 implants are safe and reliable for the repair of large defects (> or =2 cm2) in the inferior orbital wall. It seems that this is the first reported biodegradable material, in the literature, to promote bone healing along the bone fragments of the inferior orbital wall.

Reconstruction of Orbital Floor Fracture With Polyglactin 910/Polydioxanon Patch (Ethisorb): A Retrospective Study

PURPOSE

We sought to evaluate the effectiveness and the complications related to the use of Ethisorb (resorbable alloplastic material) in the reconstruction of orbital floor fractures.

PATIENTS AND METHODS

We retrospectively reviewed the charts of all patients who underwent orbital floor fracture reconstruction with Ethisorb since 2001. We only included patients with a minimum follow-up of 3 months. The following data were recorded for every patient: age, gender, cause of trauma, time from trauma to surgery, signs and symptoms, concomitant ocular injuries, radiographic analysis, pertinent intraoperative findings (including the type of approach), follow-up time, and postoperative complications.

RESULTS

Eighty-seven patients were included in the study. Twenty-one patients (24.1%) experienced postoperative complications. Of these, only 3 patients (3.4%) had permanent complications directly related to the Ethisorb membrane (diplopia, enophthalmos). Two of these patients required revision surgery and are discussed in the article.

CONCLUSIONS

The results of our study demonstrate the effectiveness of Ethisorb in the repair of small-to-moderate orbital floor fracture defects (up to a maximum size of 2 x 2 cm).

A novel bioabsorbable composite membrane of Polyactive® 70/30 and bioactive glass number 13-93 in repair of experimental maxillary alveolar cleft defects

A novel bioabsorbable composite membrane of polyethylene oxide terephthalate and polybutylene terephthalate copolymer (Polyactive 70/30) combined with bioactive glass No. 13--93 was tested in the repair of experimental maxillary alveolar cleft defects. In this pilot study, the possible ability of the membrane to promote bone formation by guided tissue regeneration was investigated. Standard alveolar defects were made bilaterally in the maxilla of 12 growing rabbits and were filled with autogenous bone grafts. The test defect was covered with the composite membrane and the other defect was left uncovered to serve as a control. The follow-up time was 10 weeks. Radiological, histological, and histomorphometric evaluations were performed. Radiologically, no statistically significant differences between test and control defects at 10 weeks were found. Histologically, the membrane enhanced osteogenic activity locally at the membrane-bone interface. Swelling of the membrane was observed. Histomorphometrically, no significant promotion of bone formation by the membrane was observed. The composite membrane was found to be biocompatible and surgically easy to use, but its osteopromotive effect was limited in this experimental cleft model. Further studies are necessary to assess its suitability for reconstructive surgical applications.

Current perspectives on ophthalmic mycoses

Fungi may infect the cornea, orbit and other ocular structures. Species of Fusarium, Aspergillus, Candida, dematiaceous fungi, and Scedosporium predominate. Diagnosis is aided by recognition of typical clinical features and by direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. Culture confirms the diagnosis. Histopathological, immunohistochemical, or DNA-based tests may also be needed. Pathogenesis involves agent (invasiveness, toxigenicity) and host factors. Specific antifungal therapy is instituted as soon as the diagnosis is made. Amphotericin B by various routes is the mainstay of treatment for life-threatening and severe ophthalmic mycoses. Topical natamycin is usually the first choice for filamentous fungal keratitis, and topical amphotericin B is the first choice for yeast keratitis. Increasingly, the triazoles itraconazole and fluconazole are being evaluated as therapeutic options in ophthalmic mycoses. Medical therapy alone does not usually suffice for invasive fungal orbital infections, scleritis, and keratitis due to Fusarium spp., Lasiodiplodia theobromae, and Pythium insidiosum. Surgical debridement is essential in orbital infections, while various surgical procedures may be required for other infections not responding to medical therapy. Corticosteroids are contraindicated in most ophthalmic mycoses; therefore, other methods are being sought to control inflammatory tissue damage. Fungal infections following ophthalmic surgical procedures, in patients with AIDS, and due to use of various ocular biomaterials are unique subsets of ophthalmic mycoses. Future research needs to focus on the development of rapid, species-specific diagnostic aids, broad-spectrum fungicidal compounds that are active by various routes, and therapeutic modalities which curtail the harmful effects of fungus- and host tissue-derived factors.

Blow-Out Fracture of the Orbital Floor in Early Childhood

Because of the anatomy of the developing bones in early childhood, blow-out fractures are rare before the age of 8 years. We present two cases where after a fall, computed tomography examinations revealed a blow-out fracture of the left orbital floor in a 12-month-old child and 27-month-old child. Because no associated symptoms were noted, both cases were managed conservatively.

In vivo efficacy of bone-marrow-coated polycaprolactone scaffolds for the reconstruction of orbital defects in the pig

Alloplastic materials offer a number of advantages over bone autografts in the reconstruction of craniofacial defects. These include: lack of donor site morbidity, unlimited quantities of available material, and the possibility to conform exactly to the defect. An ideal bioresorbable material would degrade slowly, and have osteoconductive properties to allow replacement and remodeling by osseous tissue. This is seldom observed, the materials instead being replaced by fibrous tissue. Polycaprolactone (PCL), an FDA-approved bioresorbable polymer, has several properties that might make it suitable for reconstruction of craniofacial defects. The technique of fused deposition modeling (FDM) allows for the fabrication of highly reproducible bioresorbable 3D scaffolds. The nature of the fully interconnected pore network might enhance vascular ingrowth and osteoconductive properties. It was hypothesized that coating the scaffolds in bone marrow might enhance bone formation due to the osteoinductive nature of the bone-marrow mesenchymal cells. This study aimed to test these hypotheses in the pig model. Defects measuring 2 x 2 cm were surgically created in each orbit of eight Yorkshire pigs. The orbits were divided into three groups: Group 1 (n=4), no reconstruction (control); Group 2 (n=6), reconstruction with no coated PCL scaffolds; and Group 3 (n=6) reconstruction with bone-marrow-coated PCL scaffolds. The results were evaluated at 3 months by histological and histomorphometric analyses. The defects in Group 1 were covered with fibrous scar tissue. The shape of the reconstructed area was insufficient. The defects in Groups 2 and 3 were reconstructed correctly. In Group 2 the noncoated scaffolds showed 4.5% of new bone formation compared with 14.1% in Group 3, which is statistically significant (p<0.05). The entirely interconnected 3D polycaprolactone scaffold seems to be a promising material. It induces the bone ingrowth required for reconstructing craniofacial and orbital defects. Further long-term evaluations of these PCL scaffolds must be made in order to confirm these conclusions.

Orbital floor reconstruction with flexible Ethisorb patches: a retrospective long-term follow-up study

OBJECTIVE

The purpose of the study was to investigate whether a flexible, biodegradable material (Ethisorb) shows better long-term results with regard to diplopia, bulbus motility, and exophthalmos/enophthalmos compared to the use of lyophilized dura-patches and polydioxanone (PDS) foils.

METHODS

During a period of 6 years 435 patients with an orbital fracture were investigated retrospectively. Inclusion criteria were patients with fractures of the orbital floor with a maximum size of 2 x 2 cm. Bulbus motility, exophthalmos, enophthalmos, and diplopia were investigated during a period of 2 years.

RESULTS

One hundred twenty orbital floors were reconstructed by lyophilized dura-patches, 81 by PDS, and 136 by Ethisorb. An exploration without an implantation was performed in 91 patients. The long-term investigation 12 to 15 months after surgery showed an exophthalmos and enophthalmos incidence of 1%, whereas a reduced bulbus motility and diplopia were found in 5% and 4%, respectively. Fifteen to 24 months after surgery 2% of the patients had an exophthalmos and 1% had an enophthalmos. A reduction of bulbus motility was found in 4% of the patients, and diplopia was found in 3%. The use of Ethisorb resulted in a significantly lower incidence of exophthalmos 3 months after surgery compared to PDS.

CONCLUSION

The low rate of acquired bulbus motility demonstrates acceptable results in using Ethisorb in the floor of the orbit.

The efficacy of resorbable plates in head and neck reconstruction

OBJECTIVE/HYPOTHESIS

The advent of malleable macroporous resorbable plates has allowed the surgeon a greater range of reconstructive options and has decreased the morbidity of conventional plating procedures. Completely malleable after warming to 55 degrees C, resorbable plates can readily conform to most morphologic appearances of fractures or defects and provide rigid fixation when cooled. The plating systems used in head and neck reconstruction are described.

STUDY DESIGN

Nine patients were selected for reconstruction using a resorbable plating system. The resorbable system was tested under a variety of clinical situations including frontal sinus fractures (three patients), midface fractures (two patients), mandibular defects (two patients), and laryngeal fractures (two patients).

METHODS

Each case was evaluated for rigidity of fixation, and ease of plate contouring and application. Furthermore, the postoperative functional and cosmetic results and complications were contrasted between the resorbable plating systems and each surgeon's vast experience with traditional plating systems.

RESULTS

The resorbable plating system was found to be as effective as traditional plating systems with respect to rigidity of fixation, functional results, and complications. In addition, the resorbable system was far easier to contour and, consequently, to apply, while producing higher cosmetic satisfaction after plate resorption than traditional plating.

CONCLUSIONS

Based on our experience, resorbable plates appear to be safe, easy to contour and apply, as well as effective for a wide range of head and neck reconstructive applications. In addition, the shortcomings of permanently retained plates such as plate migration, bone growth restriction, and imaging artifact are avoided.

Effectiveness of operative treatment of internal orbital wall fracture with polydioxanone implant

Many implants, some made from teflon or silicone, have been used for internal orbital wall reconstruction. Late complications relating to use of such implants have been reported. In this prospective study a polydioxanone (PDS) implant absorbable in vivo was used for internal orbital wall reconstruction. Follow-up involved clinical examination, magnetic resonance imaging (MRI) and computerized tomography (CT). Clinical examinations were undertaken before operation and up to 36 weeks postoperatively. Sixteen consecutive patients (10 pure blow-out fractures, six with associated zygomatic fracture) took part in the study. Prevalences of diplopia, proptosis and enophthalmus were recorded during each follow-up examination. This study revealed no muscle entrapment within the fracture line. Although CT results confirmed bone growth in the internal orbital wall, shape was unsatisfactory, and orbital volume was not reduced. MRI revealed thick scar formations in six cases (37.5%), fibrotic sinuses filled with air or gas in three cases (19%) and a fibrotic sinus with fluid around the PDS in one case (6%). Our results suggest that use of PDS in reconstructing the internal orbital wall is inadvisable.

Developments in craniomaxillofacial surgery: use of self-reinforced bioabsorbable osteofixation devices

Because of the problems associated with the conventional osteofixation devices used in craniomaxillofacial surgery, absorbable devices present an appealing alternative. Devices made of the polymers polylactide, polyglycolide, and their copolymers (PLGA and P[L/DL]LA) are currently the most commonly used. Ultrahigh-strength implants can be manufactured from these polymers with the self-reinforcing technique. Over the authors' almost two decades of study, both in experimental and clinical settings, self-reinforced devices have proved to be biocompatible, easy to handle, and mechanically strong, even for the fixation of femoral neck fractures. In craniomaxillofacial surgery, the authors have used self-reinforced devices for over 8 years without complications. Because of the more favored degradation characteristics, currently the copolymeric self-reinforced devices (P[L/DL]LA, Biosorb FX and PLGA, Biosorb PDX; Elite Performance Technologies, Solana Beach, Calif.) represent the advancing front in the application of absorbable devices in craniomaxillofacial surgery. The authors' share their experience and their studies of self-reinforced devices, which possess the highest strength and ductility of all bioabsorbable products.

Bioabsorbable scaffolds for guided bone regeneration and generation

Several different bioabsorbable scaffolds designed and manufactured for guided bone regeneration and generation have been developed. In order to enhance the bioactivity and potential osteoconductivity of the scaffolds, different bioabsorbable polymers, composites of polymer and bioactive glass, and textured surface structures of the manufactured devices and composites were investigated in in vitro studies and experimental animal models. Solid, self-reinforced polyglycolide (SR-PGA) rods and self-reinforced poly L-lactide (SR-PLLA) rods were successfully used as scaffolds for bone formation in muscle by free tibial periosteal grafts in animal experiments. In an experimental maxillary cleft model, a bioabsorbable composite membrane of epsilon-caprolactone and L-lactic acid 50/50 copolymer (PCL/LLA) film and mesh and poly 96L,4D-lactide (PLA96) mesh were found to be suitable materials for guiding bone regeneration in the cleft defect area. The idea of solid layer and porous layer combined together was also transferred to stiff composite of poly 70L,30DL-lactide (PLA70) plate and PLA96 mesh which structure is introduced. The osteoconductivity of several different biodegradable composites of polymers and bioactive glass (BG) was shown by apatite formation in vitro. Three composites studied were self-reinforced composite of PLA70 and bioactive glass (SR-(PLA70 + BG)), SR-PLA70 plate coated with BG spheres, and Polyactive with BG.

Laminin-coated poly(L-lactide) filaments induce robust neurite growth while providing directional orientation

Cellular channels during development and after peripheral nerve injury are thought to provide guidance cues to growing axons. In tissue culture where these cues are absent, neurites from dorsal root ganglion neurons grow with a radial distribution. To induce directional axonal growth and to enhance the rate of axonal growth after injury, we have designed microfilaments of poly(L-lactide). We demonstrate that dorsal root ganglia grown on these filaments in vitro extend longitudinally oriented neurites in a manner similar to native peripheral nerves. The extent of neurite growth was significantly higher on laminin-coated filaments compared with uncoated and poly-L-lysine-coated filaments. As high as 5.8 +/- 0.2 mm growth was observed on laminin-coated filaments compared with 2.0 +/- 0.2 mm on uncoated and 2.2 +/- 0.3 mm on poly-L-lysine-coated filaments within 8 days. Schwann cells were found to grow on all types of filaments. They were, however, absent in the leading edges of growth on laminin-coated filaments. Photolysis of Schwann cells caused a significant reduction in the neurite length on all types of filaments. Laminin-coated filaments, however, induced significantly longer neurites compared with uncoated and/or poly-L-lysine-coated filaments even in the absence of Schwann cells. Our results suggest that laminin-coated poly(L-lactide) filaments are suitable for inducing directional and enhanced axonal growth. Implants designed by arranging these microfilaments into bundles should aid regenerating axons by providing guidance cues and channels to organize matrix deposition, cell migration, axon growth, and improve functional recovery.

Lag-screw fixation of anterior mandibular fractures using biodegradable polylactide screws: a preliminary report

PURPOSE

The purpose of this study was to evaluate the utility of biodegradable, self-reinforced poly-L-lactide screws (SR-PLLA) for lag-screw fixation of anterior mandibular fractures.

PATIENTS AND METHODS

SR-PLLA lag-screws were used to stabilize anterior mandibular fractures in 11 patients. Maxillomandibular fixation was used to treat concomitant mandibular condyle fractures for 2 weeks in four patients and for 1 and 5 weeks in two patients. Clinical and radiologic follow-up lasted for 6 months in 36% of patients and for 1 year in 64%.

RESULTS

Healing of all anterior fractures was uneventful, with no displacement or delay of bony union. No adverse reactions to the biodegradable screws were seen during follow-up.

CONCLUSION

Biodegradable SR-PLLA screw fixation seems to be a new and promising way of treating anterior mandibular fractures.

Repair of orbital blow-out fractures with nasoseptal cartilage

The goals of reconstruction in orbital blow-out fractures are to restore floor continuity, provide support of orbital contents, and prevent fibrosis of soft tissues. Although ease of use has popularized alloplasts, autogenous material provides greater biocompatibility and results in low rates of infection, extrusion, and migration. Nasoseptal cartilage is an easily accessible, abundant, autogenous source that provides support to the orbital floor and minimal donor site morbidity. Thirteen patients who presented with orbital blow-out fractures underwent reconstruction with nasoseptal cartilage. Follow-up at 3 months to 4 years shows one patient with persistent manifest enophthalmos requiring further augmentation. There were no recipient or donor site complications. Nasoseptal cartilage is an underutilized and superior material for reconstruction of orbital blow-out fractures.

Lactosorb panel and screws for repair of large orbital floor defects

In a series of five patients with extensive fractures of the orbital floor, we used a biodegradable sheet for bridging of the bony defects. To achieve optimal support of the orbital contents in their anatomically correct position, we fixed the sheet with at least two resorbable screws to the infraorbital rim. This new technique appears to be superior to conventional methods because it offers reproducible results without the need for secondary interventions.

Absorbable polyglycolide devices in trauma and bone surgery

Poly(glycolic acid) or polyglycolide (PGA) is a polymer of glycolic acid. Glycolic acid is produced during normal body metabolism and is known as hydroxyacetic acid. Strong implants can be manufactured from this polymer with a self-reinforcing (SR) technique and used in the treatment of fractures and osteotomies. Since 1984, SR-PGA implants have been used routinely in our hospital for internal fixation of bone fractures. These implants were studied extensively in experimental animals and proved biocompatible. In 1.7% of human cases, sinus formation may develop after the use of these implants, which does not disturb healing. Use of these absorbable implants is justified as it obviates the need for a second operation for implant removal and avoids the risks associated with biostable implants.

Neomembranes: a concept review with special reference to self-reinforced polyglycolide membranes

Absorbable implants are being increasingly used in various fields of medicine. Important materials for these applications include the polyesters polylactide and polyglycolide. Following implantation of any absorbable device there occurs a proliferation of fibrous tissue, which along with material from the degrading implant forms a composite membranous structure-a neomembrane. Neomembranes can be exploited in guiding tissue regeneration. Success in this respect has been achieved in treatment of bone defects, nerve defects, and periodontal ligaments. Future research may ultimately permit taking advantage of neomembranes in the reconstruction of more complex organs such as the liver. Gaining an understanding of implant characteristics and implant-tissue interaction is essential for further progress in this area.