The use of hydroxyapatite cement in secondary craniofacial reconstruction.

Sixty-one patients underwent secondary craniofacial reconstruction for contour defects using hydroxyapatite cement over a 3-year period (20-month mean follow-up). There were 56 children, aged 2.2 to 18 years (mean, 10.7 years), 21 boys and 35 girls. This is the first series of pediatric patients in whom the use of hydroxyapatite cement has been reported. There were five adults aged 21 to 46 years (mean, 32 years), 3 men and 2 women. Thirty-one patients underwent reconstruction for secondary orbitocranial defects after surgery for synostosis, 7 after surgery for hypertelorism, 10 for posttraumatic skull defects, and 13 for a variety of other facial skeletal defects. There were seven complications (11 percent), ranging from a retained drain to postoperative seromas, all of which required reoperation without loss of the contour correction. All of the complications occurred in the first 18 months of our study. There has been excellent retention of implant volume with no recurrence of contour defects to date. We have not found any visible evidence of interference with craniofacial growth over the study period. We conclude that hydroxyapatite cement is a versatile and safe biomaterial when used for the correction of secondary craniofacial contour defects in children and adults. The coupling of antibiotics with this biomaterial may have applications in the treatment of osteomyelitis.     

Utility of tricalcium phosphate and osteogenic matrix cell sheet constructs for bone defect reconstruction

AIM: To determine the effects of transplanting osteogenic matrix cell sheets and beta-tricalcium phosphate (TCP) constructs on bone formation in bone defects.METHODS: Osteogenic matrix cell sheets were prepared from bone marrow stromal cells (BMSCs), and a porous TCP ceramic was used as a scaffold. Three experimental groups were prepared, comprised of TCP scaffolds (1) seeded with BMSCs; (2) wrapped with osteogenic matrix cell sheets; or (3) both. Constructs were implanted into a femoral defect model in rats and bone growth was evaluated by radiography, histology, biochemistry, and mechanical testing after 8 wk.RESULTS: In bone defects, constructs implanted with cell sheets showed callus formation with segmental or continuous bone formation at 8 wk, in contrast to TCP seeded with BMSCs, which resulted in bone non-union. Wrapping TCP constructs with osteogenic matrix cell sheets increased their osteogenic potential and resulting bone formation, compared with conventional bone tissue engineering TCP scaffolds seeded with BMSCs. The compressive stiffness (mean ± SD) values were 225.0 ± 95.7, 30.0 ± 11.5, and 26.3 ± 10.6 MPa for BMSC/TCP/Sheet constructs with continuous bone formation, BMSC/TCP/Sheet constructs with segmental bone formation, and BMSC/TCP constructs, respectively. The compressive stiffness of BMSC/TCP/Sheet constructs with continuous bone formation was significantly higher than those with segmental bone formation and BMSC/TCP constructs.CONCLUSION: This technique is an improvement over current methods, such as TCP substitution, and is useful for hard tissue reconstruction and inducing earlier bone union in defects.     

Auricular reconstruction: indications for autogenous and prosthetic techniques

Learning Objectives: After studying this article, the participant should be able to: 1. Describe the alternatives for auricular reconstruction. 2. Discuss the pros and cons of autogenous reconstruction of total or subtotal auricular defects. 3. Enumerate the indications for prosthetic reconstruction of total or subtotal auricular defects. 4. Understand the complexity of and the expertise required for prosthetic reconstruction of auricular defects.The indications for autogenous auricular reconstruction versus prosthetic reconstruction with osseointegrated implant-retained prostheses were outlined in Plastic and Reconstructive Surgery in 1994 by Wilkes et al. of Canada, but because of the relatively recent Food and Drug Administration approval (1995) of extraoral osseointegrated implants, these indications had not been examined by a surgical unit in the United States. The purpose of this article is to present an evolving algorithm based on an experience with 98 patients who underwent auricular reconstruction over a 10-year period. From this experience, the authors conclude that autogenous reconstruction is the procedure of choice in the majority of pediatric patients with microtia. Prosthetic reconstruction of the auricle is considered in such pediatric patients with congenital deformities for the following three relative indications: (1) failed autogenous reconstruction, (2) severe soft-tissue/skeletal hypoplasia, and/or (3) a low or unfavorable hairline. A fourth, and in our opinion the ideal, indication for prosthetic ear reconstruction is the acquired total or subtotal auricular defect, most often traumatic or ablative in origin, which is usually encountered in adults. Although prosthetic reconstruction requires surgical techniques that are less demanding than autogenous reconstruction, construction of the prosthesis is a time-consuming task requiring experience and expertise. Although autogenous reconstruction presents a technical challenge to the surgeon, it is the prosthetic reconstruction that requires lifelong attention and may be associated with late complications. This article reports the first American series of auricular reconstruction containing both autogenous and prosthetic methods by a single surgical team.     

Long term follow-up of reconstruction with allogeneic mandibular bone crib packed with autogenous particulate cancellous bone marrow

Allogeneic mandibular bone processed by the deep frozen method was used as a biologic crib for mandibular reconstruction. The allogeneic mandible is biocompatible, bioresorbable, of low antigenicity and provides the morphology for symphysis contour, angle of mandible and dental arch form. The particulate cancellous bone marrow (PCBM) contains marked osteogenic potential of hematopoietic marrow, which promotes osteogenesis. The cancellous marrow graft lacks structure and requires a crib to house it during the bone regeneration to the consolidation phase. Fresh frozen mandible was hollowed out for packing with PCBM prior to securing it to the defect by a rigid fixation method. Four cases of large mandibular defects resulting from treatment of benign odontogenic tumors were reconstructed utilizing this technique. All cases showed excellent facial contour and function satisfactorily in mastication and pronunciation. Complete graft incorporation and restoration of the osseous continuities were observed for four to 12 years after the operation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Use of fast-setting hydroxyapatite cement for secondary craniofacial contouring

Patients who have previously had surgical correction of major craniofacial deformities will often have residual contour deformities they wish to have improved at a later date. The development of hydroxyapatite cement has simplified these procedures. The setting time is reduced to 5 to 8 minutes by mixing the cement with a phosphate-based solution, increasing the tensile strength, and maintaining the same biocompatibility and osseoconductivity. This study includes 48 patients who presented with a variety of residual contour irregularities secondary to a craniofacial congenital anomaly or a posttraumatic defect. All but one of the patients with congenital craniofacial conditions had their initial surgical correction performed by the senior author (Magee) and had regular follow-up visits. Variable amounts of hydroxyapatite cement were used according to the size of the defect to be corrected. Five patients had a postoperative complication: two infections, one seroma, one persistent swelling, and one drain retention. Patients were followed from 6 months to 3 years (mean, 1 year 5 months). Good results were achieved in 38 patients, acceptable results with minor asymmetries were seen in seven patients, and three other patients required a second intervention to obtain a better contour. Cranioplasty with fast-setting hydroxyapatite cement is a simple and reliable procedure, with a low complication rate. Attention to simple technical and operative principles can provide excellent results.     

Determination of bone and tissue concentrations of teicoplanin mixed with hydroxyapatite cement to repair cortical defects

A highly specific and sensitive isocratic reversed-phase high performance liquid chromatography (HPLC) method for the determination of the major component of teicoplanin in tissue is reported. Comparing fluorescamine and o-phthalaldehyde (OPA) as derivatizing agents, the derivative formed with the latter exhibits superior fluorescence intensity allowing detection of femtomole quantities. Pretreatment for tissue samples is by solid-phase extraction which uses Bakerbond PolarP C(18) cartridges and gives effective clean up from endogenous by-products. Linearity was given from 0.6 to 100 ng per injection. The coefficient of variation did not exceed 5.8% for both interday and intraday assays. It was found that when bone defects are repaired with a hydroxyapatite-teicoplanin mixture, the antibiotic does not degrade, even when it is in the cement for several months. The stability of teicoplanin in bone cement was determined fluorodensitometrically.     

Porous hydroxyapatite as a bone graft substitute in cranial reconstruction: a histometric study

To assess the potential of a porous hydroxyapatite matrix to serve as a bone graft substitute, bilateral 15 X 20 mm craniectomy defects were reconstructed in 17 dogs with blocks of implant and split-rib autografts. Specimens were retrieved at 3, 6, 12, 24, and 48 months, and undecalcified sections were prepared for microscopy and histometry. The implant and graft cross-sectional areas did not change with time, documenting their equivalent ability to maintain cranial contour. Bone ingrowth extended across the implant from one cranial shelf to the other in 15 specimens. Little apparent bone ingrowth was seen in most graft specimens. Two implants and three grafts were nonunited, possibly due to lack of fixation or the orientation of the histology sections. The implant specimens were composed of 39.3 percent hydroxyapatite matrix, 17.2 percent bone ingrowth, and 43.5 percent soft-tissue ingrowth. The graft specimens were composed of 43.7 percent bone and 56.3 percent soft tissue. This study supported the thesis that a porous hydroxyapatite matrix may function in part as a bone graft substitute. The brittle hydroxyapatite matrix undoubtedly became stronger with bone ingrowth, but the degree of cranial protection achieved was not measured in this study. The size of the cranial defect used in this study did not permit estimation of the distance over which bone ingrowth may be reliably expected. There remains a need for greater understanding of the causes of nonunion, the extent of predictable ingrowth depth, and the strength of the resultant implant-bone composite.     

Determination of standards for hydroxyapatite as bone substitute

Hydroxyapatite ceramic for surgical implants is a material that meets the ASTM F 1185-88 standard. A standard defines specifications for the manufacturer, in particular in the area of quality control. A standard like this provides the necessary basis for clinical use, but only the approval of the public health department provides a fully adequate basis for broader application.     

Magnetic hydroxyapatite bone substitutes to enhance tissue regeneration: evaluation in vitro using osteoblast-like cells and in vivo in a bone defect

In case of degenerative disease or lesion, bone tissue replacement and regeneration is an important clinical goal. In particular, nowadays, critical size defects rely on the engineering of scaffolds that are 3D structural supports, allowing cellular infiltration and subsequent integration with the native tissue. Several ceramic hydroxyapatite (HA) scaffolds with high porosity and good osteointegration have been developed in the past few decades but they have not solved completely the problems related to bone defects. In the present study we have developed a novel porous ceramic composite made of HA that incorporates magnetite at three different ratios: HA/Mgn 95/5, HA/Mgn 90/10 and HA/Mgn 50/50. The scaffolds, consolidated by sintering at high temperature in a controlled atmosphere, have been analysed in vitro using human osteoblast-like cells. Results indicate high biocompatibility, similar to a commercially available HA bone graft, with no negative effects arising from the presence of magnetite or by the use of a static magnetic field. HA/Mgn 90/10 was shown to enhance cell proliferation at the early stage. Moreover, it has been implanted in vivo in a critical size lesion of the rabbit condyle and a good level of histocompatibility was observed. Such results identify this scaffold as particularly relevant for bone tissue regeneration and open new perspectives for the application of a magnetic field in a clinical setting of bone replacement, either for magnetic scaffold fixation or magnetic drug delivery.     

Repair of large defect of frontal bone with free graft of outer table of parietal bones.

We present a case with a full-thickness bony defect in the frontal area. It was corrected successfully by a free bone graft to the outer table from the parieto-occipital area, partly covered by a flap of periosteum from the same area.     

A contraindication for the use of hydroxyapatite cement in the pediatric population

The authors report on their experience with a particular hydroxyapatite cement in the pediatric population and review cases that elucidate potential limitations of its use in this population. In all patients, the implant was used for recontouring and augmenting the cranial vault. Seven of 15 patients had a direct communication between sinus mucosa and the implant at the time of surgery. Three of the seven patients developed late postoperative inflammatory reactions of the surgical site with delamination of the implant. Each patient required an aggressive irrigation and débridement with removal of the delaminated hydroxyapatite. Pathologic findings showed evidence of a foreign body inflammatory reaction in the tissue, and mixed bacterial flora were identified in all specimens. No late problems with the cement were seen in patients without a communication to the sinuses. Our findings suggest that the use of BoneSource, an essentially nonviable, nonvascularized implant, in areas exposed to bacterial contamination is contraindicated in the pediatric population. BoneSource and other similar hydroxyapatite biomaterials do have a role as implants in the craniofacial skeleton. The indications and contraindications of these substances will need to be further defined for wide acceptance to occur.     

Transplantation of an osteoarthrotendinous allograft with autogenous soft-tissue coverage for thumb reconstruction

A fresh-frozen thumb osteoarthrotendinous allograft and autogenous coverage were used to reconstruct a thumb. Immunosuppressants were not used. The components of the composite allograft are present and functioning 1 year post-operatively. Host cells have replaced and are replacing bone and tendinous structures. The "survival" of this osteoarthrotendinous allograft may have important implications in the treatment of patients with previous digital amputations, congenital absence of digits, and amputated digits that have failed replantation or are not replantable because of severely damaged vessels.     

同种异体骨移植治疗大段骨缺损的研究进展

同种异体骨已成为临床上治疗创伤、感染、先天性骨病及肿瘤切除所致的大段骨缺损的重要材料.本文主要从同种异体骨愈合机制、制备保存、临床应用效果、排斥反应及预防方法四个方面就同种异体骨移植治疗大段骨缺损的研究进展作一综述,为临床骨缺损治疗提供理论支持.     

Ligand-modified aminobisphosphonate for linking proteins to hydroxyapatite and bone surface

An increase in bone resorption is one of the main symptoms of osteoporosis, a disease that affects more and more individuals every day. Bisphosphonates are known to inhibit bone resorption and thus are being used as a treatment for osteoporosis. Aminobisphosphonates present a functionality that can be easily used for conjugation to other molecules, such as peptides, proteins, and ligands for protein recognition. In this study, an aminobisphosphonate conjugated with biotin was used as a model linker for protein attachment to bone. With this system, the interaction of biotinylated aminobisphosphonate with hydroxyapatite, a major mineral component of bone, was investigated. Quantification of the binding of aminobisphosphonate to hydroxyapatite was performed using a fluorescently labeled antibody for biotin. Additionally, the interaction of the biotinylated aminobisphosphonate with multiple treatments of cortical bone from the midshaft of a cow femur was studied. It was demonstrated that modified aminobisphosphonate reagents can bind hydroxyapatite and bone at high levels, while the biotin functionality is free to be recognized by the fluorescently labeled antibiotin antibody, suggesting that modified aminobisphosphonates could be used to link other peptides or proteins to the bone surface.     

Long-term outcome of autogenous rib graft nasal reconstruction.

Whereas reconstruction of the hypoplastic nose with rib grafting is common, the long-term outcomes of nasal growth and aesthetics are unknown. This study assessed nasal morphometrics, patient satisfaction, and the perception of nasal appearance by others up to 15 years after nasal reconstruction using cantilevered autogenous chondro-osseous rib grafting with rigid internal fixation in children. Records of all patients who received nasal rib grafts between 1983 and 1998 by one senior surgeon were reviewed. Patients in this study were operated on before their late teens and had greater than 1-year follow-up including serial photographic documentation. Nasal growth was determined by comparing anthropometric measurements preoperatively, perioperatively, and postoperatively. Patient satisfaction was determined through a questionnaire that addressed memory, donor-site morbidity, and nasal perception. Independent, blinded skilled observers who reviewed frontal and lateral photographs of the preoperative, perioperative, and postoperative intervals assessed nasal aesthetics. Thirty-two patients who underwent 38 rib graft reconstructions of the nasal dorsum and tip at an average age of 8.8 years constitute the study population. Six patients underwent secondary augmentation. The average interval between initial nasal reconstruction and evaluation for this study was 7.9 years. Comparative anthropometric measurements before and after surgery documented increases in both tip projection (2.3 percent) and nasal length (3.0 percent) and a decrease in nasolabial angle (1.9 percent). Patient satisfaction interview response rate was 100 percent of those whom we were able to contact (28 of 32). The average age at interview was 17.2 years. Most patients recalled the operation and denied recollection of pain. Donor-site long-term morbidity was not an issue for 86 percent of patients. Sixty-four percent of patients remembered their preoperative nasal appearance and 89 percent of these preferred the postoperative change and were not concerned with nasal scars or texture. Almost two-thirds of the patients had fixation screws removed from the nasal dorsum because of skin erosion, easy palpability, or visibility. Although several patients expressed a desire to make minor additional changes to their nose, only one of these elected offered presurgical consultation and none have had such surgery. The postoperative nasal appearance compared with that preoperatively was rated as improved for 66.3 percent of responses, 26.5 percent as unchanged, and 7.2 percent as deteriorated. Cantilevered autogenous chondro-osseous rib graft reconstruction of the nasal dorsum is an effective means of reconstruction for the hypoplastic nose in childhood with respect to morphometric measurements, patient self-perception, and the assessment of nasal appearance by others.     

Modified autogenous latissimus breast reconstruction and the box top nipple

During the past 3 years, the authors have been using the modified autogenous latissimus myocutaneous flap (MALF) for breast reconstruction in increasing numbers because of occasional patient and surgeon dissatisfaction with other methods of breast reconstruction. They have found this method to have unprecedented reliability, making it preferable to other forms of reconstruction in many patients. Considering the very low morbidity, the high patient satisfaction, and current economic factors, the authors are strong advocates of this form of reconstruction. A procedural outline proposed by McCraw and coworkers is followed, with some useful modifications. An elliptical transverse skin paddle is centered over the back fat roll. The area of the skin ellipse measures approximately 8 +/- 2 cm vertically and 30 +/- 5 cm transversely. After making the skin incision, a feathering technique is used in all directions through the fatty layer overlying the latissimus and in the tissue beyond the anteroposterior borders of the latissimus (not beyond 5 cm from the skin incision). By means of feathering, the shape of a breast mound can be created in the allowable tissue supported by the latissimus. A 180-degree rotation of the flap allows dependentvenous drainage and more bulk in the inferior outer quadrant, where it is needed. In the current series of 47 modified autogenous latissimus breast reconstructions, seromas were common. Other complications included one wound infection, one ulnar neuropraxia, and one fat necrosis. There were no flap necroses (partial or complete) or hematomas. The rarity of complications supports the use of this technique in selected patients. An innovative new technique for nipple reconstruction is also described. The "box top technique" of nipple reconstruction consists of four deepithelialized local flaps covered with a skin graft from the groin.