Bone Regeneration with a Combination of Adipose-Derived Stem Cells and Platelet-Rich Plasma

Mesenchymal stem cells (MSCs) have the potential to directly differentiate into osteogenic cells and efficiently regenerate bone tissue. Adipose-derived stem cells (ASCs) have the potential to differentiate into an osteogenic lineage, too. In addition, ASCs can be readily harvested in large numbers with low donor-site morbidity. Meanwhile, recent reports have demonstrated that platelet-rich plasma (PRP) contains a variety of growth factors and may be a powerful biological autologous cocktail of growth factors for tissue engineering.We have shown that ASC/PRP admixture had dramatic effects on bone regeneration in a rat calvarial defect model, not only through the osteogenic potential of ASCs, but also through the release of cytokines by platelets in PRP, which, in turn, support ASCs.In this chapter, we introduce the bone regeneration using a combination of ASCs and PRP in a rat calvarial defect model.

Efficacy of freeze-dried platelet-rich plasma in bone engineering

OBJECTIVE

Platelet-rich plasma (PRP) is typically isolated and applied immediately after preparation, making it both a time- and labor-intensive addition to the operative procedure. Thus, it would be convenient if PRP could be preserved. We evaluated the efficacy of freeze-dried PRP (FD-PRP), as compared with freshly isolated PRP (f-PRP) for bone engineering.

DESIGN

FD-PRP was prepared by lyophilization of f-PRP and was subsequently preserved at -20°C for one month. It was then rehydrated with an equal or 1/3 amount of distilled water (×1FD-PRP, ×3FD-PRP, respectively), and we assessed its gelation properties and the release of growth factors (PDGF-BB, TGF-β1, and VEGF). We also examined the bone forming ability with onlay-grafting on mice calvaria using β-TCP granules as a scaffold.

RESULTS

FD-PRP showed comparable gelation as f-PRP. In terms of growth factor release,×1FD-PRP released identical concentrations of PDGF-BB and TGF-β1 to f-PRP, while ×3FD-PRP released approximately 3-fold concentrations when compared with f-PRP. In vivo, ×1FD-PRP promoted identical levels of the bone formation as f-PRP, and ×3FD-PRP induced more abundant bone formation.

CONCLUSIONS

These results suggest that f-PRP can be stored without functional loss by freeze-drying and the concentration of PRP may improve its efficacy in bone engineering.

Comparison of microstructures between block grafts from the mandibular ramus and calvarium for horizontal bone augmentation of the maxilla: a case series study

The primary purpose of this clinical study was to compare architectural metric parameters using microcomputed tomography (micro-CT) between sites grafted with blocks harvested from the mandibular ramus and calvarium for horizontal bone augmentation in the maxilla. The second aim was to compare the primary stability of implants placed in both types of block grafts. Ten consecutive healthy partially edentulous patients requiring extensive horizontal bone reconstruction in the maxilla were included. A total of 14 block grafts (7 each from the mandibular ramus and calvarium) were studied. After 4 to 6 months of healing, 41 implants were placed: 24 implants (58.5%) in calvarial (group 1) and 17 (41.5%) in ramus grafts (group 2). A resonance frequency analysis (RFA) was performed to test implant stability. Furthermore, two biopsy specimens were randomly selected for histomorphometric analysis. Micro-CT analyses showed no significant difference in the morphometric parametric values analyzed between groups. Furthermore, RFA also showed no difference between groups. However, slightly higher RFA values were noted for implants placed in ramus grafts. Bone quality, as assessed by micro-CT and histomorphometric analyses, was similar in both ramus and calvarial block grafts. In addition, there was no difference in primary implant stability between groups.

A computer-designed scaffold for bone regeneration within cranial defect using human dental pulp stem cells

A computer-designed, solvent-free scaffold offer several potential advantages such as ease of customized manufacture and in vivo safety. In this work, we firstly used a computer-designed, solvent-free scaffold and human dental pulp stem cells (hDPSCs) to regenerate neo-bone within cranial bone defects. The hDPSCs expressed mesenchymal stem cell markers and served as an abundant source of stem cells with a high proliferation rate. In addition, hDPSCs showed a phenotype of differentiated osteoblasts in the presence of osteogenic factors (OF). We used solid freeform fabrication (SFF) with biodegradable polyesters (MPEG-(PLLA-co-PGA-co-PCL) (PLGC)) to fabricate a computer-designed scaffold. The SFF technology gave quick and reproducible results. To assess bone tissue engineering in vivo, the computer-designed, circular PLGC scaffold was implanted into a full-thickness cranial bone defect and monitored by micro-computed tomography (CT) and histology of the in vivo tissue-engineered bone. Neo-bone formation of more than 50% in both micro-CT and histology tests was observed at only PLGC scaffold with hDPSCs/OF. Furthermore, the PLGC scaffold gradually degraded, as evidenced by the fluorescent-labeled PLGC scaffold, which provides information to tract biodegradation of implanted PLGC scaffold. In conclusion, we confirmed neo-bone formation within a cranial bone defect using hDPSCs and a computer-designed PLGC scaffold.

Dimethyloxaloylglycine improves angiogenic activity of bone marrow stromal cells in the tissue-engineered bone

One of the big challenges in tissue engineering for treating large bone defects is to promote the angiogenesis of the tissue-engineered bone. Hypoxia inducible factor-1α (HIF-1α) plays an important role in angiogenesis-osteogenesis coupling during bone regeneration, and can activate a broad array of angiogenic factors. Dimethyloxaloylglycine (DMOG) can activate HIF-1α expression in cells at normal oxygen tension. In this study, we explored the effect of DMOG on the angiogenic activity of bone mesenchymal stem cells (BMSCs) in the tissue-engineered bone. The effect of different concentrations of DMOG on HIF-1a expression in BMSCs was detected with western blotting, and the mRNA expression and secretion of related angiogenic factors in DMOG-treated BMSCs were respectively analyzed using qRT-PCR and enzyme linked immunosorbent assay. The tissue-engineered bone constructed with β-tricalcium phosphate (β-TCP) and DMOG-treated BMSCs were implanted into the critical-sized calvarial defects to test the effectiveness of DMOG in improving the angiogenic activity of BMSCs in the tissue-engineered bone. The results showed DMOG significantly enhanced the mRNA expression and secretion of related angiogenic factors in BMSCs by activating the expression of HIF-1α. More newly formed blood vessels were observed in the group treated with β-TCP and DMOG-treated BMSCs than in other groups. And there were also more bone regeneration in the group treated with β-TCP and DMOG-treated BMSCs. Therefore, we believed DMOG could enhance the angiogenic activity of BMSCs by activating the expression of HIF-1α, thereby improve the angiogenesis of the tissue-engineered bone and its bone healing capacity.

Reconstruction of saddle nose deformity with calvarial bone graft

OBJECTIVE

To evaluate the efficacy of calvarial bone in the reconstruction of saddle nose deformity.

METHODS

The cross-sectional study was conducted at the Plastic Surgery Unit of Imam Reza Hospital, Tabriz University of Medical Sciences, Iran, from July 2004 to October 2009. It comprised 19 patients who underwent saddle nose deformity reconstruction with calvarial bone graft. All patients were operated upon under general anaesthesia. They were followed up periodically.

RESULTS

The patients followed up for 25 to 61 months for an average period of 39.2 +/- 4.3 months. In 14 (74%) patients the result of the surgical intervention was excellent, while in 5 (26%) it was acceptable. All patients were satisfied and there was not displacement, absorption, distortion or infection of the graft.

CONCLUSION

Calvarial bone graft is a viable option for the reconstruction of saddle nose deformity, especially in severe cases.

[Cranial reconstruction using autologous split calvarial bone combined with calcium phosphate bone cement: a case report]

We report a case of cranial reconstruction using autologous split calvarial bone combined with calcium phosphate bone cement (CPC). A 19-years-old man suffered from cranium defect and rhinorrhea originating from frontal skull base fracture in a traffic accident. After CSF hydration treatment had finished, continuously we performed cranial reconstruction with autologous split calvarial bone so that the patient could return to work at an early stage. The use of autologous split calvarial bone with CPC was able to increase stability of the construct and provide excellent cosmetic result in our short follow up period. The combination use of these two materials may be useful for cranial reconstruction in patients with cranium defect.

[Prevention of osseous defaults in the craneosinostosis surgery using calvarian cranial particulate bone]

It is considered that up to 20% of the craniosinostosis patients require secondary surgeries. Different techniques have been used in craneofacial surgery for the reconstruction of great osseous defects in pediatric patients for many years. This paper is about a new technique to obtain osseous graft for covering osseous cranial defects, using particulate bone, harvested from the patient calvarian using a hand-driven brace and covered with a fibrin adhesive. This is a very simple technique, which provides a great amount of bone from the patient himself, therefore producing a small morbidity. Since 2007 the authors have been using autologous particulate bone harvested from de patient calvarian for the reconstruction of different size osseous defects found in craneofacial surgery, especially in pediatrics patients. Although alloplastic materials and bone substitutes have been used for cranial reconstruction, the best option is the autogenous bone. In contrast to synthetic materials autologous grafts have a faster osteointegration, due to their osteogenic, osteoinductive and osteconductive properties. Harvesting the bone from the calvarian patient produces a minimal morbidity compared to the extraction of grafts from other donor sites such as rips or hip. The use of autologous particulate bone in craniosinostosis surgery reduces the risk of second interventions due to secondary ossifications defects. On the other hand, the harvest is easy and the supply of bone it is enough in pediatric patients.

[Comparative study of onlay bone graft absorption of outer cortex from mandible and cranium]

OBJECTIVE

To investigate the value of application of mandibular outer cortex as bone graft by comparing its bone absorption with cranial outer cortex.

METHODS

8 minitype grown-up pigs at the age of 8 - 12 months underwent surgery of taking out the same size (2.5 cm x 1.0 cm) of outer cortex from mandible and craninium. The volume of the outer cortex was measured by volume-displacement method. Then the outer cortex of mandible and cranium were onlay grafted to the each side of the pig snout, respectively. 12 weeks later, 2 pigs were randomly selected for histological examination. The other 6 pigs were killed 24 weeks after surgery for measurement of the bone graft volume and histologic examination.

RESULTS

The bone graft absorption rate was (41 +/- 5)% for mandibular outer cortex and (46 +/- 12)% for cranial outer cortex, showing no significant difference between them (P = 0.51). The histologic examination results also had no marked difference in the bony healing and reforming between the two graft.

CONCLUSIONS

Mandibular outer cortex is a good donor site for onlay bone graft in craniofacial region.

SYMPTOMATIC MASS EFFECT OF A HYPERTROPHIED PERICRANIAL FLAP AFTER REPAIR OF A DURAL DEFECT

OBJECTIVE

To detail a potential complication of the use of vascularized pericranial flaps in the repair of dural defects, namely, flap hypertrophy secondary to venous engorgement.

CLINICAL PRESENTATION

A 23-year-old man with a left parietal lobe hemangiopericytoma underwent a craniotomy for tumor resection. The resultant dural defect was repaired with a vascularized pericranial flap. On postoperative Day 3, the patient developed headache, confusion, aphasia, and right upper extremity apraxia. Imaging revealed an extra-axial collection at the craniotomy site; on reexploration, a swollen, engorged pericranial flap causing mass effect was found.

INTERVENTION

The pericranial flap was excised.

CONCLUSION

In this case, hypertrophy of the vascularized pericranial flap is hypothesized to have occurred because of venous congestion, possibly secondary to restriction of venous outflow by the overlying bone flap.

Maxillary and Mandibular Reconstruction Using Bicortical Calvarial Bone Grafts: A Retrospective Study of 122 Reconstructions in 73 Patients

BACKGROUND

Using classic maxillary and mandibular reconstruction with mandibular bone grafts or unicortical calvarial bone grafts, the authors performed 122 reconstructions in 73 patients using bicortical calvarial bone grafts and report the results in this article. Such a technique has not been previously described in the world literature.

METHODS

Seventy-three patients, 55 women and 18 men, with severely atrophied maxillas or mandibles were treated with bicortical calvarial bone grafts and placement of implants over a 5-year period. Patient selection was based on the important insufficient remaining height or width of bone placement of multiple 10-mm implants and the thinness of the calvaria (<5 mm). All patients had major bone atrophy.

RESULTS

Twenty-nine patients had 121 implants placed in vertical bicortical bone grafts and 40 patients had 170 implants placed in horizontal bicortical bone grafts. All patients underwent a two-stage procedure, with the implants being placed 4 to 5 months after the grafting procedure. The majority of maxillary implants were placed between the canine eminence and zygomatic buttress. Of the 122 bicortical calvarial bone grafts that took, two cases presented an incised wound of the dura. A simple nonabsorbable suture was performed in these two cases without any postoperative problems. There were no cerebral injuries encountered with the donor sites.

CONCLUSIONS

Bicortical bone grafting seems to be a solution for reconstruction of voluminous bone atrophy in cases of thin calvaria. Because of legal issues, such a technique must be performed by a trained craniofacial surgery team. The resorption rate seems to be lower in cases of bicortical bone graft.

Reconstruction of orbital floor and maxilla with divided vascularised calvarial bone flap in one session

We present four cases which underwent reconstruction of orbital floor and anterior maxillary wall with a vascularised bone flap following partial maxillectomy. After tumour resections, superficial temporal artery (STA) and vein based calvarial bone flaps from the outer tabula were prepared. Without disrupting the integrity of fascia and periosteum, the bone was separated into two segments in the same direction as the blood flow and one is 3 cm and the other 5 cm. The two bone segments were transferred as one single flap and one segment of the flap was used to reconstruct the orbital floor and the other for reconstruction of the anterior maxillary wall. Since two cases had large skin defects, lateral frontal skin to which the frontal branch of the STA supplies blood was incorporated into the flaps. Functional and aesthetic results were satisfactory at the end of 8-20 months follow-up. This technique allowed reconstruction of the orbital floor and anterior maxillary wall and even skin defects with a single pedicled flap in one session.

Composite Hemiface/Calvaria Transplantation Model in Rats

BACKGROUND

Extensive craniomaxillofacial deformities including bone and soft-tissue defects are always challenging for reconstructive surgeons. The purpose of this study was to extend application of the face/scalp transplantation model in the rat by incorporation of the vascularized calvarial bone, based on the same vascular pedicle, as a new treatment option for extensive craniomaxillofacial deformities with large bone defects.

METHODS

Seven composite hemiface/calvaria transplantations were performed across major histocompatibility complex barrier between Lewis-Brown Norway and Lewis rats. Seven donor and seven recipient rats were used in this study. Hemicalvarial bone and face grafts were dissected on the same pedicle of the common carotid artery and jugular vein and were transplanted to the deepithelialized donor faces. All rats received tapered and continuous doses of cyclosporine A monotherapy. Evaluation methods included flap angiography, daily inspection, computed tomographic scan, and bone histology.

RESULTS

Flap angiography demonstrated the vascular supply of the bone. The average survival time was 154 days. There were no signs of rejection and there was no flap loss noted at 220 days posttransplantation. Bone histology at days 7, 30, 63, and 100 after transplantation revealed viable bone at all time points, and computed tomographic scans taken at days 14, 30, and 100 revealed normal bones without resorption.

CONCLUSIONS

For extensive face deformities involving large bone and soft-tissue defects, this new osteomusculocutaneous hemiface/calvaria flap model may serve to create new reconstructive options for covering during one surgical procedure.

The osteogenic potential of adipose-derived stem cells for the repair of rabbit calvarial defects

INTRODUCTION

Bone replacement is often necessary during reconstruction of craniofacial anomalies or trauma. Adipose-derived stem cells (ASCs) possess osteogenic potential and are a promising cell source for bone tissue engineering. The present study was designed to assess the osteogenic potential and utility of using ASCs to regenerate bone in a rabbit calvarial defect model.

METHODS

Rabbit ASCs were seeded on gelatin foam (GF) scaffolds and induced in osteogenic medium containing bone morphogenetic protein (BMP)-2. Thirty-four 8-mm calvarial defects were randomly treated with autograft, no treatment, GF scaffold, GF + ASCs, or GF + osteoinduced ASCs. After 6 weeks, calvaria were harvested and underwent histologic and radiologic analyses to compare healing between the treatment groups.

RESULTS

Defects treated with autograft underwent complete healing. Radiologically, there were no significant (P > 0.05) differences in healing among empty defects, and those treated with GF alone or GF plus osteoinduced ASCs. Osteoinduced ASCs exhibited significantly (P < 0.05) greater healing than noninduced ASCs.

CONCLUSION

Preimplantation osteoinduction of ASCs enhances their osteogenic capacity. Lack of a significant osteogenic effect of ASCs on calvarial healing at 6 weeks may be secondary to use of noncritical-sized defects. Larger defects would likely demonstrate the osteogenic potential of ASCs more definitively.

Use of precontoured positioning plates and pericranial flaps in midfacial reconstruction to optimize aesthetic and functional outcomes

OBJECTIVES

To present our experience with reconstruction of midfacial defects using "precontoured positioning plates" with or without pericranial flaps and to describe our technique in detail.

METHODS

Thirty-two consecutive patients with midfacial defects subsequent to oncologic resection that were reconstructed primarily with cranial bone grafts and precontoured positioning plates were reviewed for type of defect, functional outcome, complications, and postoperative appearance.

RESULTS

Primary reconstruction of all defects in this series was performed. Defects involved the orbital rim, orbital floor, or both in 28 patients (88%), the body of the zygoma in 24 patients (75%), and extended to the skull base in 16 patients (50%). Pericranial flaps were used to cover the bone grafts in 22 patients (69%). Postoperative radiotherapy was performed in 22 patients (69%), preoperative radiotherapy in 5 (16%), and the other 5 (16%) had no radiotherapy. There were no intraoperative complications, and postoperative complications included plate exposure (n = 2), ectropion (n = 3), and partial bone graft loss or resorption subsequent to completion of radiotherapy (n = 2). Postoperatively, appearance was excellent in 24 patients, fair in 6 patients, and poor in 2 patients. Secondary reconstructive procedures were performed in 4 patients (12%). Follow-up ranged from 12 months to 6 years (median, 4.2 years).

CONCLUSIONS

Precontoured positioning plates with or without pericranial flaps enable precise reconstruction of midfacial defects with precise incorporation of cranial bone grafts. In our series we routinely covered the bone grafts with well-vascularized tissues, leading to a low incidence of complications and excellent aesthetic results.

Comparison of bone formation ingrafted periosteum harvested from tibia and calvaria

Periosteum covers the bone surface and displays the potential to initiate bone formation, after injury to the bone. Numerous studies have demonstrated that the periosteum plays major roles in the healing process after bone fracture. Some reports have described that in the healing of long bone fractures, the periosteum forms new bone by intramembranous and endochondral ossification. Other researchers insist that healing of defects in membrane bone shows bone formation by intramembranous ossification. However, previous studies have not been able to clarify differences in bone formation patterns. We hypothesized that differences in bone formation pattern are associated with the periosteal potential for cell differentiation. The present study grafted periosteum, harvested from the tibia and calvaria, into the suprahyoid muscle, with the aim of interrupting release of factors from bone matrix. Bone formation, after grafting periosteum, harvested from the tibia and calvaria, was examined histologically and radiographically. Grafted tibial periosteum formed a large area of new bone by intramembranous and endochondral ossification, while grafted calvarial periosteum displayed intramembranous ossification. Grafted tibial periosteum formed a larger area of bone than grafted calvarial periosteum. Patterns of cell differentiation thus differ between grafted periosteum, harvested from the tibia and calvaria.

Novel Approach to Calvarial Bone Transport Using a Rabbit Model

Calvarial defects sometimes require cranioplasty to protect the brain. Alloplastic materials, such as acrylic resin, hydroxyapatite ceramics, and titanium, involve various problems, such as vulnerability, infection, deformity resulting from growth, and high cost. We devised a new bone transport model in the rabbit based on the distraction osteogenesis theory of Ilizarov. Twelve Japan white rabbits with a mean body weight of 2.5 kg aged 12 weeks were used. Craniectomy (7 x 14 mm) was performed in 12 rabbits. Trapezoid bone osteotomy was performed anterior to the calvarial defect in 10 rabbits. The distraction device (Extension-plates) was fixed between the trapezoid bone island and the skull. Distraction was initiated 5 days postoperatively. The device was activated once every other day, with approximately 0.75 mm or 0.5 mm per activation. Bone distraction was continued until the rod could not be moved. The lengths of distraction were 4 mm in two cases, 5 mm in one case, 6 mm in one case, and 7 mm in two cases, with a mean of 5.5 +/- 0.56 mm. Both radiographic and histological findings showed osteogenesis by intramembranous ossification and trans-chondroid bone formation. Distraction osteogenesis has potential clinical applications in cranioplasty, especially in children because usage of autogenous bone is difficult if not impossible in most cases.

Bone Regeneration in Osseous Defects Using a Resorbable Nanoparticular Hydroxyapatite

PURPOSE

This animal study examined the de novo bone formation in bony defects following the insertion of autogenous bone alone versus an injectable nanoparticle hydroxyapatite alone and in combination with 25% autogenous bone. The regenerative potentials of the tested materials were compared with each other.

MATERIALS AND METHODS

A model with biological similarity to humans with regard to bone regeneration was a prerequisite for the transferability of the results to clinical practice. Therefore, the adult domestic pig was the animal of choice. A total observation period of 6 months was selected. Microradiographic and histologic evaluation of the bone specimens was completed at 8 defined times.

RESULTS

Microradiography indicated mineralization rates in the 2 bone substitute groups that were not significantly lower than those found in the autogenous bone group. Histologically, there was suitable osseointegration and osteoconduction of the used material. Complete resorption of the nanoparticle hydroxyapatite had taken place after 12 weeks.

CONCLUSIONS

It can be concluded that the evaluated nanoparticular hydroxyapatite met the clinical requirements for a bone substitute material within the limits of this experimental setting. Due to its microstructure, complete resorption took place during the course of this study.

Autogenous Bone Grafts and Bone Substitutes???Tools and Techniques: I. A 20,000-Case Experience in Maxillofacial and Craniofacial Surgery

Alloplastic bone substitutes can be used to alter facial contour. In contrast, autogenous bone grafts have a successful 80-year history of restoring facial contour as well as the basic functional support of the craniofacial skeleton. The traditional procedures for harvesting and using autogenous bone grafts are not obsolete. During the past 30 years, the techniques have been refined and new sources have been found, such as calvarial grafts. New tools were required and have been designed to make harvesting of grafts easier and faster for the surgeon and safer and less expensive for the patient. Four short articles under the heading of "Techniques and Tools" are presented addressing the harvesting of (1) iliac, (2) costal, (3) tibial, and (4) calvarial grafts. These articles are based on the experience of six surgeons using the same technique and instruments in more than 20,000 autogenous bone grafting procedures. (These figures represent the group experience as of 2001. Since then, one of the junior coauthors has retired, but the remaining five continue to harvest autogenous bone grafts on a regular basis. So, the group experience as of 2004 is in the range of 23,000 procedures). The-senior surgeon's experience of 9500 procedures spans a period of 50 years (from 1946 to 1996). For the other surgeons (10,500 procedures combined), the collection period was 25 years (from 1975 to 2000).

[Suspending of M. temporal, temporal fascia and parietal periosteum to correct late facial palsy]

OBJECTIVE

To explore a simply, effective dynamical method to correct late facial palsy.

METHODS

The method of suspending of M. temporalis, temporal fascia was reformed below: (1) To prolong flap of M. temporalis, temporal fascia by parietal periosteum. (2) To elevate the reversal level of compound flap. (3) To fill depressed temporal area by silica gel piece.

RESULTS

The compound flap is united structurally and long enough to transfer. Temporal defect is recontoured. And zygomatic area is no longer protruded.

CONCLUSIONS

The reformative method resists defect of the old one and obtains a dynamical result.

Long-term stability of autogenous bone grafts following combined application with guided bone regeneration

The aim of the study was to compare the long-term stability of membranous and endochondral autogenous bone grafts with or without combined application of guided bone regeneration (GBR). Twenty-five, male, 6-month old, albino rats were used in the study. The animals were divided into four groups (A5, A11, B5 and B11). Group A5 (control): The inferior border of the mandible was exposed in both sides. At one side of the jaw, a calvarial bone graft (baseline -3 x 4 x 0.64 mm) was placed at the inferior border of the mandible and was fixed with a standardized screw-type titanium microimplant. At the contralateral side, an ischiac bone graft (baseline -3 x 4 x 0.87) was transplanted. The healing period was 5 months. Group A11 (control): The animals were treated in the same manner as in Group A5 with the difference that the healing period was 11 months. Group B5 (test): The animals were treated in the same manner as in Group A5 with the difference that an e-PTFE membrane was adapted over the bone graft on each side of the jaw. Group B11 (test): The animals were treated in the same manner as in Group B5 with the difference that 5 months following transplantation the animals were subjected to a second operation and the membranes were removed. The healing period was 11 months. The animals were killed at 5 (Groups A5 and B5) or at 11 months (Groups A11 and B11) following mandibular augmentation and the jaws were defleshed. The width, the length and the thickness/height of the bone graft were evaluated by means of a stereomicroscope. At 5 months, both types of the membrane-treated bone grafts presented increase in all dimensions compared with baseline. However at 11 months, both types of the membrane-treated bone grafts exhibited a decrease in their dimensions which were similar to the baseline measurements. In the control groups, both types of bone graft presented significant resorption both at 5 and at 11 months with the ischiac bone grafts presenting more resorption in width and length than the calvarial bone grafts. It can be concluded that the long-term volume stability of autogenous endochondral and membranous onlay bone grafts combined with GBR is superior to that of autogenous endochondral and membranous onlay bone grafts alone.

Alveolar Ridge Augmentation: A Comparative Longitudinal Study Between Calvaria and Iliac Crest Bone Grafts

Insertion of endosseous implants is often difficult because of lack of supporting bone. In the case of severe atrophy of the jaws, a large volume of autogenous bone can be harvested from the iliac crest and calvaria. Both grafts undergo partial resorption with time, but the rate of bone loss has not been fully elucidated. The aim of this study was to evaluate the alveolar bone height gain (ABHG) obtained with iliac crest and calvaria bone grafts. Twenty-five patients had mandibular bone grafts, 32 had maxillary bone grafts, and 11 had both mandibular and maxillary bone grafts. Measures were made on preoperative, postoperative, and follow-up radiographs. A general linear model was used to evaluate the rate of ABHG plotted against months elapsed from the time of the operation to the time of follow-up. General linear model output showed a statistically significant effect for only the type of donor bone graft (P = .004), with a better ABHG for calvaria. The iliac crest bone grafts lost most of the ABHG in the first 6 months, whereas calvaria bone grafts lost ABHG over a greater interval of time. The type of bone graft is the strongest predictor of ABHG, and calvaria bone graft had a higher stability than did iliac bone graft. However, the gap in ABHG between the 2 grafts tended to decrease over time.

Midfacial Reconstruction Using Calvarial Split Bone Grafts

OBJECTIVE

To evaluate the success rate of free calvarial grafts for midfacial reconstruction, the relevance of soft tissue coverage, and the influence of radiotherapy.

DESIGN

Retrospective analysis.

SETTING

University medical center.

PATIENTS

Fifty-six patients (27 tumor cases, 24 trauma cases, and 5 others) underwent bony midface reconstruction using calvarial grafts in the past 11 years. Half of the patients with tumor were additionally treated with radiation.

INTERVENTIONS

A total of 95 bone transplants were used for reconstruction of the zygoma, orbit, and nasal bone. Graft survival and complications were evaluated. Grafts with total and partial soft tissue coverage were compared. The influence of radiotherapy in the tumor patient group was determined.

RESULTS

Graft survival was 95.8%. One nasal dorsum graft was totally resorbed. Infection occurred in 9 cases, leading to only 1 total and 2 partial graft losses. The incidence of dysfunction of the eye due to globe malposition after reconstruction of the orbital walls was low. A correlation between radiation and transplant loss as well as between soft tissue coverage and graft survival could not be found.

CONCLUSIONS

For midfacial reconstruction, it is not necessary to fully cover calvarial bone grafts by the surrounding soft tissue. Even in patients who will undergo postoperative irradiation, calvarial bone grafts are a reliable alternative in selected cases.

Atrophic mandible reconstruction using calvarial bone grafts and implant-supported overdentures: radiographic assessment of autograft healing and adaptation

Bone grafting constitutes a vital surgical procedure in the management of severely atrophic mandibles. In this regard, calvarial bone autografts are applied in the reconstruction of wide mandibular defects caused by edentulousness and long-term denture-related resorption. Grafts are used as a framework to augment the residual ridge and provide implant stability for further prosthetic restoration. On the basis that radiographic evidence corresponds to biologic changes in bone response to transplantation and loading, the goal of this article is to document the radiographic assessment of calvarial autologous bone grafts in the recipient site. Panoramic radiographs were used to evaluate bone changes occurring during both the graft healing period and graft adaptation after implant loading. Emerging data show that conventional panoramic radiography may have an effect on the investigation of bone grafts and provide initial information about graft incorporation and adaptation.

Reconstruction of burr hole by using autologous button-shaped graft harvested from inner table of craniotomy flap: technique and clinical result

Patients who underwent craniotomy occasionally complain about the postoperative cosmetic appearance at the site of burr holes on the scalp. This problem occurs as a result of depletion of the skin into the unreconstructed burr holes. Some materials have been developed for reconstruction of craniotomy burr holes. To prevent the postoperative cosmetic deformity, the authors developed a button-shaped autologous bone graft harvested from the inner table of craniotomy flap. Clinical application of this method is described.

Three-layer reconstruction with fascia lata and vascularized pericranium for anterior skull base defects

BACKGROUND

We report an assessment of the efficiacy of a triple layer graft composed of fascia lata and vascularized pericranium for anterior skull base reconstruction. This technique is based on the concept that vascularized tissue over a free flap may promote vascularization and rapid wound healing.

METHOD

A large fascial graft is prepared from the fascia lata and divided in two pieces and trimmed to a size larger than the bone and dural defect. Vascularized pericranium is harvested after bicoronal incision and elevating the bifrontal scalp flap down to the supraorbital rims. First is dural repair, which is performed with fascia lata placed between the brain and remaining dura. Second, fascia lata is placed over the skull base defect and secured with mini titanium screws over the cranial surface of the orbital ridges. Third, vascularized pericranium is laid between the two layers of fascia lata.

FINDINGS

We studied 17 patients of whom 2 had malignancy, 6 had olfactory groove meningioma, 6 had skull base fracture and rhinorrhea, 1 case had orbital meningioma, 1 had invasive pituitary adenoma and 1 had basal encephalocele. The transbasal approach was used as a single procedure in 13 cases. The extended transbasal approach combined with a transfacial approach was used in 3 cases and with a pterional approach in 1 case. In each patient, reconstruction of the cranial base was performed with triple layer graft of fascia lata and vascularized pericranium. The patients were followed-up 2 months to 5 years. None of the patients experienced postoperative cerebrospinal fluid leakage, meningitis, abscess, brain herniation and tension pneumocephalus.

INTERPRETATION

Fascia lata with vascularized pericranium is highly reliable, tensile and well suited for reconstruction of the anterior skull base.

Bone autografting of the calvaria and craniofacial skeleton: historical background, surgical results in a series of 15 patients, and review of the literature

BACKGROUND

Although the use of autologous bone for reconstruction of the cranial and facial skeleton underwent a partial reappraisal following the introduction of a vast range of alloplastic materials for this purpose, it has demonstrated definite advantages over the last century and, particularly, during the last decade.

METHODS

Fifteen patients underwent cranial and/or cranio-facial reconstruction using autologous bone grafting in the Department of Neurologic Sciences-Neurosurgery and the Division of Maxillo-Facial Surgery of the Rome "La Sapienza" University between 1987 and 1995. This group of patients consisted of 8 females and 7 males whose average age was 29.5 years (range 7.5 to 59 years, mean age 30). In all these patients cranioplasty and/or cranio-facial reconstruction had been performed to repair bone defects secondary to benign tumors or tumor-like lesions (12 cases), trauma (2 cases), or, in the remaining case, to wound infection after craniotomy for a neurosurgical operation.

RESULTS

The results obtained in a series of 15 patients treated using this method are described with reference to the abundant data published on this topic.

CONCLUSION

The mechanical, immunologic, and technical-grafting properties of autologous bone, together with its superior esthetic and psychological effects, probably make it the best material for cranioplasty.

Preservation of bone flaps in patients with postcraniotomy infections

OBJECT

Management of postcraniotomy wound infections has traditionally consisted of operative debridement and removal of devitalized bone flaps followed by delayed cranioplasty. The authors report the highly favorable results of a prospective study in which postcraniotomy wound infections were managed with surgical debridement to preserve the bone flaps and avoid cranioplasty.

METHODS

Since 1990, 13 patients with postcraniotomy wound infections have been prospectively treated with open surgical debridement and replacement of the bone flap. All patients received a full course of systemic antibiotic agents based on the determination of the bacterial culture and antibiotic sensitivity. Notable risk factors for infection included prior craniotomies, radiotherapy, and skull base procedures. The mean long-term follow-up period was 35 +/- 20 months. In all five patients who underwent craniotomies without complications, bone flap preservation was possible with full resolution of the infection and without the need for additional surgery. Among the eight patients with risk factors, bone preservation was possible in six patients, although two required minor wound revisions (without bone flap removal). Both patients who underwent craniofacial procedures required an additional procedure in which the bone flap was removed for recurrent infection (one after 2 months and the other after 29 months).

CONCLUSIONS

In patients with uncomplicated postcraniotomy infections, simple operative debridement is sufficient and it is not necessary to discard the bone flaps and perform cranioplasties. Even patients with risk factors such as prior surgery or radiotherapy can usually be treated using this strategy. Patients who undergo craniofacial surgeries involving the nasal sinuses are at higher risk and may require bone flap removal.

Roles of periosteum, dura, and adjacent bone on healing of cranial osteonecrosis

It has been reported that large cranial osteonecrotic areas can heal. It was hypothesized that optimal healing is possible by the synchronized contribution of the osteogenic structures (periosteum, dura, and adjacent bone) that envelop the necrotic cranium. This hypothesis was tested by preserving or isolating the contribution of these osteogenic tissues. A total of 37 4-old-month rats were included in the study. Twelve animals were killed immediately, and cranial bone samples were taken and processed for examination (from 6 animals as fresh samples [Group A] and from the rest as autoclaved samples [Group B]). Group B was created to test if the bone was completely nonviable. In Group C (n = 25), cranial bone disks 8 mm in diameter were taken from 4-month-old rats, autoclaved, and put back onto the defect area. This group was further divided into the four Subgroups C1 through C4 (n = 7 in C3; n = 6 in C1, C2, and C4). Dura mater was isolated from the overlying bone disk with a polytetrafluoroethylene sheet in Subgroups C1 and C2, whereas the bone contacted the dura in the rest. The bone samples were covered with healthy periosteum in Subgroups C1 and C3 and with skin in Subgroups C3 and C4. These animals were killed after a healing period of 12 weeks, and the relevant bone disks were obtained. Surrounding healthy bone was also harvested from the same animals after they were killed to create Group D. The data of Group A and D were compared with those of the experimental group to comment on the degree of bone healing in the latter group. Quantitative and qualitative assessment was performed by mammography, bone densitometry, computed tomography, and histological examinations to find out the density and cellular content (osteocytes and vessels) of the samples. Examination of Group B samples showed nonviable tissue with a preserved microstructure. Analysis of other samples showed that both the periosteum and, mainly, the dura play an important role in cranial bone healing. The periosteal reaction was observed to be more evident when the dura was not separated. Cellular repopulation was more evident when both structures contributed to the healing process. Newly formed bone progressed centripetally; however, adjacent bone without the support of the dura and periosteum was capable of producing limited neovascularization and bone formation.

Mastoid obliteration: autogenous cranial bone pAte reconstruction

OBJECTIVE

To review the outcome in consecutive patients who have undergone complete epitympanic and mastoid obliteration and concurrent tympanic membrane reconstruction over a 53-month period.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

Sixty-two ears in 56 sequential patients undergoing mastoid obliteration with major indications including recurrent infection, debris trapping in the canal wall-down cavity, intolerance of water exposure, calorically induced vertigo in an existing cavity, a semicircular canal fistula, and inability to wear a hearing device. Thirty-six ears in 33 patients who underwent second-stage surgery for ossicular reconstruction during the same time period are also reviewed.

INTERVENTION

Transplanted autogenous cranial bone is used to induce osteoneogenesis resulting in complete obliteration of the epitympanic and mastoid spaces while maintaining a mesotympanic space.

MAIN OUTCOME MEASURES

Success of obliteration, incidence of symptoms prompting intervention, hearing outcome, incidence of recurrent cholesteatoma, and incidence of eustachian tube dysfunction necessitating treatment and need for revision surgical procedures.RESULTS Complete take of the bony obliteration occurs in over 95% of cases; 90% of treated patients enjoy complete absence of original symptoms, whereas symptoms improved in the remainder. For over 95% of patients, existing eustachian tube function has been adequate after obliteration. To date, no patient has required revision surgical intervention.

CONCLUSION

Mastoid obliteration with autogenous cranial bone is a safe and extremely effective option for treatment of problematic canal wall-down mastoid cavities. Surgical techniques that include sterile harvest of the cranial bone graft mixed with antibiotic, revision of the cavity to expose viable native bone, inclusion of the epitympanic spaces in the obliteration, and complete coverage of the pAte with autogenous fascia have proven critical to successful outcome.

Cranial reconstruction with computer-generated hard-tissue replacement patient-matched implants: indications, surgical technique, and long-term follow-up

The aim of this clinical study was to evaluate the effectiveness and safety of using computer-generated alloplastic (hard-tissue replacement) implants for the reconstruction of large defects of the upper craniofacial region. Fourteen patients who had large (> 150 cm2) preexisting defects of the cranium or cranio-orbital region underwent surgical reconstruction. Preoperatively, a three-dimensional computed tomographic scan was obtained from which an anatomic model was fabricated. The defect in the model was then used to create an alloplastic (hard tissue-replacement polymer) implant for reconstruction and surgical placement. At the time of surgery, the implant was secured into position with either metal or resorbable fixation. In cases where the frontal sinus was in proximity to the implant, the frontal sinus was either cranialized and covered with a pericranial flap or obliterated with hydroxyapatite cement. In cases that had been previously irradiated or infected, wide bony debridement and coverage with a vascularized muscle was initially performed, followed by implant reconstruction 6 months later. All implants fit easily into the bone defects, and only four (29 percent) required some minor adjustments to complete the fit. All patients healed uneventfully. With a minimum of 1 year follow-up (average, 3 years) in all cases, excellent contours have been maintained and all patients have remained infection-free. In large cranial defects, custom implants fabricated from porous, hydrophilic hard-tissue replacement polymer provide an exacting anatomic fit and a solid stable reconstruction. This method of reconstruction in these defects is rapid and exact, and significantly reduces operative time. Critical attention must be paid, however, to management of the frontal sinus and preexisting bone infection and the quality of the overlying soft-tissue cover.

[Use of autogenous cranial bone grafts for orbital floor reconstruction]

OBJECTIVE

To evaluate the effects of autogenous calvarial bone grafts on treatment of the patients with defect of orbital floor from facial trauma.

METHODS

During a 5-year period from April 1994 to April 1999, 34 patients ranging in age from 16 to 68 years (twenty males and fourteen females), who presented with orbital floor defects associated with other facial fractures were reconstructed by autogenous calvarial bone grafts. The surgical approach to the orbital floor involved a transconjunctival incision in 31 patients and a subciliary incision in 3 patients. After the orbital floor exploration, the bone graft was harvested through the coronal incision in 29 patients and the parietotemporal region incision in 5 patients. The bone graft was then fashioned to the appropriate size and configuration and fixed to the stable bone of the orbital floor with microplates or screws.

RESULTS

The surgical incisions healed well with a minimal scar. There were no infection, extrusion or other complications associated with autogenous calvarial bone graft. There were no cases of optic neuropathy, diplopia and enophthalmos. There was no morbidity in donor sites. One patient had slight ectropion, which lasted three months and became inconspicuous in six months. 8 cases with hypoesthesia of the infraorbital region returned the sensory function within 6 months. 6 patients with enophthalmos were partly corrected. The follow-up period ranged from 6 months to 5 years.

CONCLUSION

The orbital floor defects should be managed by early exploration to avoid later complications. The sequel, such as enophthalmos and dystopia or diplopia are much more difficult to correct after bony union. A vast array of autogenous and alloplastic materials have been used to reconstruct the defect of orbital floor. Autogenous bone graft reduces the risk of infection and extrusion. Cranial bone graft produces less donor site morbidity compared with other sites, non-visible scar as the incision is placed within the hair-bearing skin and the conjunctiva. The membranous bone from the skull has been shown to undergo less resorption and greater graft volume survival as compared to endochondral bone of the iliac crest or rib. Skull bone is an ideal source of bone graft in orbital reconstruction.

Ossification of autologous pericranium used in duraplasty. Case report

Pericranium is frequently used in duraplasty and is considered superior to the many other alternatives because of its easy availability and because it offers a watertight dural closure while minimizing the problems of adhesion, infection, and rejection. Although the osteogenic potential of all periosteal tissues is recognized, a review of the literature did not reveal a reported case of osseous formation following use of pericranium for duraplasty. The authors report the case of a 17-year-old man who presented with a self-inflicted gunshot wound to the head. He was obtunded, but moving all extremities purposefully. Computerized tomography scanning demonstrated bifrontal injury. A bicoronal craniotomy with debridement was performed on an emergency basis, with vascularized pericranium used for a duraplasty. Follow-up cranioplasty demonstrated significant ossification of the pericranium 5 months after the original surgery. Pericranium is an attractive material for duraplasty; however, its osteogenic potential may interfere with future cranioplasty and cosmesis. This may be especially relevant in young persons.

Frontal sinus obliteration with the pericranial flap

BACKGROUND

Frontal sinus obliteration is often accomplished by autologous grafts such as fat, muscle, or bone. These avascular grafts carry an increased risk of resorption and infection as well as donor site morbidity. Vascular regional flaps may be used to obliterate small sinuses with less morbidity.

OBJECTIVES

To review our experience with the use of the pericranial flap for obliteration of the frontal sinus.

METHODS

The records of 10 patients who underwent obliteration of the frontal sinus with the pericranial flap were reviewed. Demographics, indications for frontal sinus obliteration, immediate and late complications, and long-term outcome were recorded. These results were compared with those in the current literature.

RESULTS

Ten sinuses were obliterated with the pericranial flap. Indications included frontal sinus mucocele, mucopyocele, frontal sinus osteomyelitis, and frontal sinus fracture. The median follow-up was 3 years. There was 1 short-term complication of persistent headache for 1 month, and there was asymptomatic recurrence of a neofrontal sinus in 1 case.

CONCLUSIONS

The pericranial flap is a vascularized local flap that is easily harvested. The use of the pericranial flap avoids donor site morbidity associated with free fat or cancellous bone grafts. The pericranial flap arms the head and neck surgeon with an effective alternative to other methods of frontal sinus obliteration.

State-of-the-art for osteoplastic frontal sinus operation

Endoscopic ethmoid and frontal sinus surgery have reduced but not eliminated the indication for the osteoplastic adipose obliteration operation. An updated technique for this operation is presented for treating chronic frontal sinus disease, cerebrospinal fluid leakage by way of frontal sinus, and sinucutaneous fistulae.

Use of titanium mesh for reconstruction of large anterior cranial base defects

The authors evaluated the role of titanium mesh used in combination with vascularized pericranium to provide rigid support during reconstruction of anterior skull base defects. Thirteen patients with large anterior skull base defects caused by tumor invasion or traumatic injury involving the cribriform plate, orbital roof, and planum sphenoidale were included in the study. The reconstruction technique involved placement of titanium mesh between two layers of continuous vascularized pericranium. Surgical glue and routine lumbar cerebrospinal fluid (CSF) drainage were not used in any patient. At a mean postoperative follow-up time of 22 months (range 8-39 months), none of the patients had developed infection or meningocele. Postoperative CSF rhinorrhea occurred in two patients with extensive dural defects, which resolved with temporary lumbar drainage. Use of titanium mesh and a two-layer vascularized pericranial graft is a safe, reproducible, and feasible method for reconstructing the anterior skull base. Patients with large dural defects may need temporary CSF diversion to avoid postoperative fistula formation.

Extracorporeal irradiation of tumorous calvaria. Case report

This patient with recurrent meningioma grossly involving the frontal bone underwent craniotomy and tumor resection. During the procedure a bone flap was irradiated extracorporeally at a very high dose (120 Gy) sufficient to sterilize residual tumor cells, and the bone was then successfully replaced orthotopically for reconstruction. The use of autologous irradiated bone in this setting offers advantages over cadaveric transplantation and prosthetic implants. Radiation might cause less disruption of the bone's architecture than other techniques of tumor cell eradication.

[The technique and location of secondary donor sites of vascularized bone grafts in the therapeutic arsenal of the plastic surgeon]

Most of the donor sites for conventional bone grafts can also provide vascularised bone grafts. Increased progress in vascular research has enabled the harvesting of grafts that are increasingly reliable and versatile. This work does not give emphasis to classic vascularised bone transfers like the iliac crest, the fibula or the lateral border of the scapula but highlights 'secondary' sites which are often underutilized. Several donor areas are studied; the upper limb including the clavicle, the lower limb, the thorax and the cranium. The hands and toes, which constitute a specific entity, are excluded. In each chapter the authors have emphasised the fundamental points relating to the anatomy, the technique of harvesting and the indications.

Interlocking calvarial bone grafts: a solution for the short, depressed nose

OBJECTIVES/HYPOTHESIS

In patients severely affected with collapse of the nose, deprojection and upward rotation of the nasal tip are commonly seen. Traditional maneuvers to derotate and project the tip may be insufficient, because of the natural tendency of the nasal skin/soft tissue envelope to pull the tip in a cephalic and posterior direction. If the forces of scar contracture can be resisted, the tip and dorsum should remain adequately positioned.

STUDY DESIGN

Retrospective chart review of 20 cases.

METHODS

Using an open rhinoplasty approach, two strips of calvarial bone are fitted together in a tongue-in-groove fashion, and esthetics are analyzed. Rotation and projection are altered as indicated. A screw inserted at the indicated level along the caudal bone graft acts to prevent retrodisplacement of either the dorsal or caudal strut as scarring occurs.

RESULTS

The procedure has been used in 20 patients. Two patients had displacement of the dorsal bone graft. Two patients have been lost to follow-up. Follow-up in the remainder has ranged from 6 weeks to 4 and a half years. All have maintained adequate tip and dorsal projection without excess upward tip rotation. Bone grafts have undergone minimal resorption.

CONCLUSION

The interlocking calvarial bone graft technique stabilizes the nasal tip and dorsum in such a way that resists the forces of contracture and provides improved esthetics and function.

Cleft lip nose correction with onlay calvarial bone graft and suture suspension in Oriental patients

To correct the secondary cleft lip nose deformity in Oriental patients, many alar cartilage mobilization and suspension techniques have been developed. However, these techniques have critical limitations. One of the limitations is the suspension vector, and another is suspension power. The suspension vector is from inferior to superior and from the deformed alar cartilage to the normal alar cartilage. Thus, the vector is not suitable for normal nasal tip projection. The suspension power is not satisfactory because Oriental people have underdeveloped, thin alar cartilages and thick skin. So, the suspended, deformed alar cartilage may relapse and pull the normal alar cartilage to the deformed side. To overcome these limitations, the authors use the cantilever calvarial bone graft for tip projection; it also serves as a strong, rigid framework for cartilage and soft-tissue suspension. Using these techniques, the authors can create normal nasal tip projection and a normal looking nasal aperture.

Surgical technique for reconstruction of the nasal septum: the pericranial flap

BACKGROUND

We describe a new technique for the surgical reconstruction of large-sized anterior septal perforations based on the pericranial flap.

METHODS

The technique requires a standard open rhinoplasty combined with a pericranial flap harvested after a bicoronal approach and tunnelled to the nasal cavity. We present the case of a man with complete destruction of the nasal septum as a result of chronic cocaine abuse.

RESULTS

Surgery resulted in a permanent and complete closure of the perforation.

CONCLUSIONS

The main advantage of this technique is the use of well-vascularized autogenous tissue and the minimal donor site morbidity. This technique provides a new method to close large nasal perforations.

Calvarial bone graft harvest in children

Bone grafts are occasionally required in the reconstruction of bony defects in the pediatric population. Strong recommendations have existed in the past toward the use of principally inner table bone grafts in children. In this retrospective series with an upper age limit of 14 years, outer table calvarial bone grafts were used as the material of choice for bony reconstructions. There were no complications relative to the outer table graft harvest in any of these 12 patients. Discussion of harvest techniques in different pediatric age groups will be reviewed.

[Histological study and stereologic analysis of membranous versus endochondral onlay bone grafts]

OBJECTIVE

The experimental study was to determine the differences in changes in the onlay bone grafts of different embryonic origin.

METHODS

The study was designed to compare the potential for appositional bone growth in membranous and endochondral onlay grafts in New-Zealand rabbits and a rhesus monkey. Results were assessed with volumetric measurement, histological examinations and stereologic analysis with double-fluorochrome labeling technique.

RESULTS

For the membranous and endochondral bone grafts, the volumetric retention rate was (78.4 +/- 3.5)% and (56.0 +/- 5.1)% respectively. The mineralization apposition rate (MAR) was (3.6 +/- 0.8) microns/d and (0.92 +/- 0.33) micron/d; the osteoid seam width (OSW) was (14.56 +/- 2.69) microns and (7.38 +/- 2.20) microns; the tetracycline uptake rate(TUA) was (91.22 +/- 2.69)% and (51.28 +/- 4.11)%, respectively.

CONCLUSION

1. It was found that the membranous bone graft maintained its volume to a significantly greater extent than the endochondral bone graft; 2. Membranous bone grafts exhibited higher survival rate and greater activity than endochondral bone grafts; 3. Different changes were also found in the two recipient sites. There was more powerful bone regenerative reaction in the recipient bed of the membranous bone graft than the endochondral one.

Minimizing wound complications in cochlear implant surgery

OBJECTIVE

An extended postauricular incision has replaced the standard C-shaped scalp flap for cochlear implant surgery at our institution. The postoperative wound complication rates of the two incisions were evaluated.

STUDY DESIGN

This study was a retrospective case review.

SETTING

This study was performed in a tertiary referral center.

PATIENTS

A total of 256 adult and pediatric patients who underwent cochlear implantation during a 10-year period (1986 to 1996) were reviewed.

MAIN OUTCOME MEASURE

Postoperative wound complications were identified. Major complications included flap necrosis, wound dehiscence with or without implant exposure, and wound infection requiring hospitalization. Hematoma, seroma, or superficial wound infections were considered minor complications.

RESULTS

There were 6 major and 6 minor complications among 116 patients with the standard scalp flap (complication rate, 10.3%). There was only 1 minor complication among 140 implants using the postauricular incision (0.7%).

CONCLUSION

The extended postauricular incision appears to significantly reduce the incidence of wound complications in cochlear implant surgery.