The fate of preserved autogenous bone graft

Certain clinical conditions exist in which a section of cranial bone is removed but not immediately replaced at the initial procedure. Preservation of this bone can provide a valuable autogenous donor source for a future reconstructive procedure. The purpose of our study was to compare the volume retention of fresh autogenous bone with that of preserved autogenous bone as inlay and onlay cranial grafts. Two bone grafts were harvested from the skull of 15 adult New Zealand White rabbits. The graft volumes were calculated, and the graft were preserved in a normal saline-antibiotic solution at -20 degrees C. Three months later, during the second procedure, a fresh graft was harvested and then placed in the preexisting occipital defect as an inlay graft. Also at this time, the preserved grafts were placed, one as an inlay graft in the fresh occipital defect and the other as an onlay graft in the frontal region. The animals were sacrificed 3 months later, and the percentage of graft volume retention was determined. The fresh inlay grafts had a mean volume retention of 85.1 percent, while the preserved inlay nad onlay grafts had 61.8 and 75.9 percent mean volume retention, respectively. It is concluded that while fresh cranial autograft remains the "gold standard" for craniofacial reconstruction, preserved autogenous cranial bone is a viable alternative for inlay and onlay grafting of the craniofacial region.     

Biologic resurfacing of a major joint defect with cryopreserved allogeneic periosteum under the influence of continuous passive motion in a rabbit model

Periosteal autografts have been widely used for biologic resurfacing of full-thickness articular cartilage defects in rabbits. This study examined the effect of donor and recipient age on biologic joint resurfacing using fresh and cryopreserved periosteal allografts in a rabbit model. The study also assessed the ability of cryopreserved periosteal allografts to undergo neochondrogenesis. Eighty New Zealand rabbits were divided into six groups receiving combinations of fresh or cryopreserved allografts. After all the grafts were secured with fibrin glue, the animals were subjected to two weeks of continuous passive motion followed by four weeks of cage activity or intermittent active motion. The rabbit knees were analyzed at six weeks by gross examination, histochemical staining, and collagen typing. No significant difference in chondrogenic potential between fresh and cryopreserved periosteal allografts was observed. Grafts obtained from adult donors were much less chondrogenic than those from adolescents, but adults recipients experienced reasonably good results when they received allografts from young donors. No evidence of rejection was found in any of the samples as late as six weeks after transplantation.     

Autologous calvarial and iliac onlay bone grafts in miniature swine

Calvarial bone has been reported to be superior to iliac bone for onlay bone grafting due to decreased resorption. This study evaluated the physical, histologic, and radiographic characteristics of calvarial and corticocancellous iliac onlay bone grafts in nine Pitman-Moore miniature swine at 2 weeks, and at 1-, 2-, 4-, 6-, 7-, 8-, 10-, and 12-month intervals. Compared with iliac grafts, the calvarial onlay grafts had more than a twofold greater radiographic density. Statistical analysis of the mature grafts using the standard of estimated means of the bone graft volumes revealed 85% retention of the calvarial grafts compared with 34% retention of the grafted iliac bone. There was no subjective difference in the rate or degree of revascularization between the two grafted materials.     

Occipital calvarial bone graft in posterior occipitocervical fusion

STUDY DESIGN: Dorsal occipitocervical fusion is associated with a high rate of fusion failure and requires an additional surgical site for donor bone graft harvesting. In this series, an autologous occipital calvarial bone graft obtained from the same occipitocervical incision with contoured metal loops was used in 25 adults to achieve craniovertebral stabilization and fusion. OBJECTIVES: To study the use of autologous occipital calvarial bone grafts in occipitocervical fusion. SUMMARY OF BACKGROUND DATA: Cranial bone grafts have been used successfully in craniofacial reconstruction with good long-term results. In the plastic surgery literature, there are claims that membranous bone grafts are superior to endochondral bone grafts in fusions because of decreased resorption. In recent studies, results have shown successful use of calvarial bone in fusing the upper cervical spine in children. The use of autologous occipital bone in posterior occipitocervical fusions avoids many of the problems associated with traditional donor sites and provides a sufficient quantity of good quality bone for the fusion. This is especially true in the fragile rheumatoid arthritis patient with cranial cervical instability. METHOD: Split-thickness, autologous calvarial bone grafts with contoured loop and cable instrumentation were used for posterior occipitocervical stabilization and fusion in 25 patients, most of whom had rheumatoid arthritis. The calvarial bone graft was harvested from the occipital skull, using a microair impactor, and was secured next to the loop construct. After surgery, all patients were immobilized with external orthoses. RESULTS: None of the patients had hardware failure or complications from the occipital graft procurement. In 22 patients, good alignment, stability, and bony fusion were shown on radiographs. CONCLUSIONS: Occipital calvarial bone graft appears to work as well as other autologous corticocancellous bone grafts routinely used in posterior occipitocervical fusions.     

The Ranawat Award. Histology of nine structural bone grafts used in total knee arthroplasty

The cross section radiographs and histology of nine bone grafts were examined to determine whether grafts are durable enough to support a total knee implant when the load is shared by host bone, graft bone, and a stemmed component. All cases had cemented total knee arthroplasties with stemmed components adjacent to bulk grafts. The cases included autografts and allografts, which had been in situ for an average of 41 months (range, 20-62 months). Seven of the grafts were retrieved postmortem from three patients (four knees), and two were retrieved at revision surgery from one patient. The allografts all were intact, but had not revascularized. The autografts were viable bone. New bone was being laid down on the dead graft bone at the periphery of the allografts. No change in the bone to cement interface, no graft collapse, no development of radiolucent lines, and no component loosening occurred in these cases. The promising clinical results of bone grafts in total knee arthroplasties were confirmed by the examination of these grafts at the cellular level. Using stemmed components in bone grafted knee reconstructions may have increased graft durability and protected the grafts from fatigue failure.     

The neocortical local circuit--a research workshop held in Sde-Boker, Israel, May 4-8, 1997

Preoperative knowledge of skull thickness before harvesting cranial bone grafts would be ideal to help minimize intracranial complications. Previous research has demonstrated regional variations in calvaria; however, accurate preoperative and intraoperative methods of skull thickness measurement are not available. The aim of this research represents the first attempt to examine the reliability of ultrasound to determine cranial bone thickness. Four previously studied calvarial sites were marked in 10 adult male cadaveric skulls. The individual points were insonified using an A-mode ultrasonic transducer operating in pulse-echo mode. The times of flight of the waves propagating in the bone samples were compared with caliper measurements. The mean difference in cranial bone thickness was 0.16 mm, with a standard deviation of 0.09 mm. Student's t-test failed to reveal any statistically significant differences between caliper and ultrasonic measurements (p = 0.569) and Pearson's correlation coefficient supported an extremely strong and positive relationship between the two modalities (r > 0.992). Multiple linear regression models predicted that calvarial thickness could be accurately predicted by ultrasound without consideration of cadaveric specimen or sampling point location (R2 = 0.988). The convergent values between ultrasonic and caliper measurements suggest that this modality can accurately and reliably determine skull thickness. A-mode ultrasound can have significant implications in guiding the harvest of in situ split cranial bone grafts, the placement of osseointegrated implants, skull anthropometrics, and related craniomaxillofacial applications.     

Changes in the aortic endothelium and plasma von Willebrand factor levels during the onset and progression of insulin-dependent diabetes in BB rats

The superior volume maintenance of membranous over endochondral bone has been shown in several studies and provides the basis for its preferred clinical use as an onlay grafting material in the craniofacial skeleton. The scientific rationale for this seeming embryologic advantage, however, has never been proven. Our hypothesis is that the pattern of onlay bone graft resorption is primarily determined by a graft's micro-architecture (relative cortical and cancellous composition) rather than its embryologic origin (membranous versus endochondral). Twenty-five adult New Zealand, White rabbits were used for this study. Eight animals were killed at 3 weeks, eight animals at 8 weeks, and nine animals at 16 weeks. Three graft types were placed onto each rabbit cranium: cortical bone graft of membranous origin and cortical and cancellous bone graft of endochondral origin. Fluorochrome markers were injected into all living rabbits at 1, 6, and 14 weeks. Microcomputed tomography scanning was performed on all of the bone grafts to determine postsacrifice volumes and to obtain detailed information regarding the bone graft's trabecular architecture. In addition, specimens were examined histologically. Volume analysis showed a statistically greater resorption rate in the cancellous endochondral bone graft than in either the endochondral or membranous cortical bone grafts (p < 0.05) for all time points. In addition there was no significant difference in the resorption rates between the endochondral and membranous cortical bone grafts. A post-test power analysis (alpha = 5 percent) of the volume data comparing the two types of cortical bone grafts showed that a difference in resorption of 8.9 percent would be detected with a 90-percent probability. Previous studies, which have shown a seeming superiority of membranous over endochondral bone grafts, used composite grafts composed of both cortical and cancellous portions. By separating these components, we have shown that cortical bone grafts maintain their volumes significantly better than cancellous bone grafts. In addition, we found no statistical difference in the resorption rates between the two cortical onlay bone grafts of different embryologic origins, a finding that has never been previously published. From our results, we believe cortical bone to be a superior onlay grafting material, independent of its embryologic origin. We believe these results challenge the currently accepted theories of bone graft dynamics and may lead to a change in the way clinicians approach bone graft selections for craniofacial surgery.     

Revision of failed lumbar fusions. A comparison of anterior autograft and allograft

STUDY DESIGN: The radiographic and clinical results of two different anterior structural grafts were compared in 38 patients who had combined anterior-posterior revision surgery for failed lumbar fusion. OBJECTIVES: Failed lumbar fusion surgery, such as pseudarthrosis or flatback deformity, may result in disabling pain. The optimum revision technique has yet to be defined. The authors of the current study sought to determine which of two different types of anterior graft yields the best results. SUMMARY OF BACKGROUND DATA: Posterior procedures for revision of a failed lumbar fusion have not yielded reliably successful results. A combined anterior-posterior approach may be effective in restoring sagittal balance and enhancing fusion rates. Recent studies have shown femoral ring allografts to be effective in lumbar fusion revision, but no studies have compared these with other types of structural grafts. METHODS: Thirty-eight patients with pseudarthrosis were treated with combined anterior-posterior lumbar spine fusion using either femoral ring allografts (26 patients) or tricortical iliac autografts (12 patients). Radiographic follow-up examination and retrospective patient self-assessment questionnaires were used to evaluate outcomes. Results were assessed by independent reviewers after a mean follow-up period of 35 months. RESULTS: Radiographic follow-up examination revealed acceptably low pseudarthrosis rates for structural autografts (0%) and allografts (6%). The questionnaires revealed significant improvement in pain for both groups. Allograft patients showed greater improvement in function, less pain medication usage, and higher overall success rates (83%) than autograft patients (64%). CONCLUSIONS: Femoral ring allografts are as effective, clinically and radiographically, as tricortical iliac autografts when used as an anterior structural element in revision lumbar spine fusion in patients who have undergone multiple surgical procedures for pseudarthrosis or flatback deformity. The slightly greater improvement for the allograft group needs to be confirmed in a larger study.     

Induced osteogenesis for repair and construction in the craniofacial region

Solid and powdered forms of undemineralized and demineralized bone grafts were implanted in rat cranial defects. Demineralized calvarial discs healed the defects as well as did the fresh discs, as judged by histology and 45Ca incorporation. Gross and histologic evaluations demonstrated predictable endochondrial osteogenesis by demineralized bone powder (DBP). Undemineralized grafts, in contrast, showed poor and unpredictable bony healing. Construction of facial bones was achieved by implantation of demineralized bone powder within the soft tissues. The phenomenon of induced osteogenesis by demineralized implants was not species specific. These studies of osseous transformation provide insight into the mechanism of, and possible answers to, the problems of osseous transplantation.     

Optimal selection and preparation of fresh frozen corticocancellous allografts for cervical interbody spinal fusion

STUDY DESIGN: Iliac crest corticocancellous allografts for anterior interbody fusion were harvested from six cadavers. The grafts were cut sequentially from left and right crests and randomly assigned to tricortical or bicortical preparations. Their compression strengths then were determined and compared by matched pair analysis. OBJECTIVES: To quantify the failure strength of the grafts from different iliac locations and determine the optimal type of preparation of the grafts for anterior interbody fusion. SUMMARY OF BACKGROUND DATA: Iliac crest corticocancellous autografts and allografts commonly are used for interbody cervical fusions. However, graft strengths for specific sites have not been determined fully. METHODS: Six paired, fresh frozen, iliac crests were sectioned using a customized miter box into multiple 1-cm-thick grafts 1.5 cm in depth to simulate cervical interbody grafts. The left and right sides of each pair were randomly assigned to tricortical and bicortical preparations. The samples were tested by applying a compressive load to failure using a specialized fixture to simulate vertebral body loading. RESULTS: The grafts closer to the anterosuperior iliac spine had significantly higher failure loads and failure strengths than those closer to the posterosuperior iliac spine. The strengths of the bicortical grafts were 72 +/- 14% of the strengths of the tricortical grafts (P < 0.001). CONCLUSIONS: Anterior iliac crest grafts were stronger in compression, even after removal of one cortical surface, than posterior iliac crest grafts.     

Surgical outcomes using bioabsorbable plating systems in pediatric craniofacial surgery

The purpose of this study was to evaluate the surgical outcomes of the 1.5-mm LactoSorb plating system (Walter Lorenz Surgical, Inc., Jacksonville, FL, U.S.A.) used to stabilize the osteotomized calvarial bone in pediatric patients who have undergone craniofacial surgery. The records of 33 consecutive pediatric patients who underwent craniofacial surgery from January 1997 through December 1997 were reviewed. There were 18 male and 15 female patients, and the age ranged from 4 months to 12 years. Patients were followed-up at 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. For those patients reviewed, the following information is included: age, sex, diagnosis, surgical procedures, number and size of LactoSorb plates and screws used in each patient, operative difficulty of the screws and the heat pack, and postoperative complications, including wound healing, palpability, and infection. The LactoSorb plating system was used to stabilize the osteotomized calvarial bones in 33 patients who were diagnosed with: 1) craniosynostosis, 2) hydrocephalus, 3) fibrous dysplasia, or 4) cranial deformation. Orbital rim advancement and anterior cranial vault reshaping were performed in 17 patients. Posterior cranial vault reshaping, orbital rim advancement, and anterior cranial vault reshaping were performed in eight patients. Posterior cranial vault reshaping only was performed in seven patients. Excision of fibrous dysplasia from temporal bone was performed in one patient. One patient had a postoperative wound infection, and LactoSorb plates were palpable postoperatively in four patients. The LactoSorb plating system provided adequate rigidity for stabilizing the osteotomized calvarial bone during surgery and maintained adequate rigidity after surgery during the bone healing period before absorption. This plating system showed satisfactory results in pediatric craniofacial surgery patients.     

Diagnosis and treatment of osteogenic sarcomas, techniques of reconstructions. Future prospects

PATIENTS AND METHODS: We have performed 34 massive bone-cartilage grafts with a follow-up of 2 to 7 years (1988-1993) including 5 complete joint grafts of the knee. Between 1988 and 1993, 8 massive diaphyso-metaphyseal bone grafts were performed. Joint reconstructions using massive bone-cartilage allografts are increasingly used in routine oncology surgery. Long-term rehabilitation and possibilities of immediate anatomic reconstruction of the articular surface, together with mid-term results suggest that the functional results are promising compared with major reconstruction prostheses. Indications for operations are being increasingly widened to younger subjects who have undergone partial or total joint exeresis for tumour. Sleeved prostheses were used for 12 reconstructions (1988-1993) for sarcoma of the knee. RESULTS The risk of sepsis are comparable for the different groups and are mainly related to the quality of the skin repair during chemotherapy. Fractures of the graft occur when the fixation is insufficient or when rehabilitation exercises were too aggressive. Non-consolidation was exceptional when the junction between the allograft and the receiver bone is not surrounded with autologous spongious autografts. Joint instability and arthrosis depend on the stability of the ligament reconstruction. To this day, no Charcot type joint disease has been demonstrated, periarticular innervation has maintained joint trophism. DISCUSSION: There are still some incompletely resolved problems concerning the revascularization of the graft, its integration into the skeleton, the outcome of the grafted cartilage and that of the ligament formations attached to the graft or used as allografts. These massive grafts must be studied over a longer period of time but the early results are encouraging. Sleeved grafts using bone-bank specimens could be an intermediary solution which appears to be indicated in cases where the tumoural resection was particularly large removing bone, cartilage, ligaments and muscles. With these sleeved prostheses, the muscles can be refixed onto the graft thus reducing the risk of shank fracture and loosening. The use of a tibial graft with the patellar tendon is helpful in reconstructing the extensor apparatus. However, if rehabilitation is not undertaken rapidly and followed regularly for several months, the graft favours the development of muscular adherances which can be a major limitation to joint mobility.     

A paradigm of experimentally induced mild hyperthyroidism: effects on nitrogen balance, body composition, and energy expenditure in healthy young men

OBJECTIVE: To conceptualize, with fine needle aspiration cytology (FNAC), the early cellular events occurring in and around fresh autogenous and allogenic bone grafts during the first 40 postimplantation days. STUDY DESIGN: Forty-eight cases of bone grafts were studied by FNAC at serial intervals of 10, 20, 30 and 40 postimplantation days. Twenty patients were recipients of autogenous grafts, 16 received 0.6N HCI partially decalcified allogenic bone implants, and 4 received combined autogenous and allogenic bone grafts (included in the allograft group). There were eight control cases of closed fracture shaft femur, which were managed conservatively. RESULTS: The initial cellular responses in autogenous grafts, allografts and controls appear to be a part of the nonspecific reparative process followed by a more specific phase, with a steady increase in relative lymphocyte count from the 20th day onwards. Osteogenesis, as judged by osteoblasts and osteoclasts, was also comparable. CONCLUSION: Partially decalcified allografts appear to be a good substitute for autogenous bone grafts in clinical practice when adequate autogenous material is not available. FNAC is a good technique for studying bone graft responses without interfering with graft uptake. It is helpful in the early detection of subclinical infection or any other pathology at the graft site.     

Interrelations of soft and hard tissues for osseointegrated implants

Success in using osseointegrated dental implants-optimal function, esthetics, and phonetics-requires selection of the treatment modality that is optimal for the patient, protection of tissue blood supply, and adherence to a plan based on a thorough analysis of all deviations from the normal anatomy. The options for correction of hard-tissue deficiencies are mechanical modification of the implants and reconstructive surgery. Mechanical approaches reduce the time needed for reconstruction but direct the occlusal forces in unnatural directions. Surgical reconstruction is preferable. Any bone graft must be precisely fitted to the recipient site to facilitate revascularization. Restoration of hard-tissue dimensions usually requires soft-tissue coverage and augmentation. There are two basic options: (1) flaps with or without inlay or onlay grafts and (2) controlled tissue expansion. An onlay graft can help restore soft-tissue height and width. Inlay grafts have greater vascularity than onlay grafts, and the color matching is better. Controlled tissue expansion creates "like" tissue without a secondary defect, and fewer tissue transfers are needed. However, the technique is difficult, and the patient must make multiple visits to the office. For implant placement to be successful, the patient's expectations must be understood, and the benefit-to-risk ratio should be extremely high.     

Biomechanical and histologic alteration of facial recipient bone after reconstruction with autogenous bone grafts and alloplastic implants: a 1-year study

Potential alteration of the underlying recipient bone resulting from a graft or implant has significant clinical relevance. The present study was designed to evaluate the biomechanical and histologic alteration of facial recipient bone with autogenous bone graft and alloplastic implants over a 1-year period. The bilateral arches of 15 rabbits were randomized between four groups: (1) control (n = 6), subperiosteal exposure of the zygomatic arch was made; (2) onlay (n = 12), bone graft was placed as an onlay to the zygomatic arch; (3) inlay (n = 6), bone graft was placed as an inlay within the zygomatic arch; (4) implant (n = 6), a stainless steel plate was placed as an onlay to the zygomatic arch. Animals were killed 1 year after grafting. In the onlay groups, all steel implants and half of the onlay bone grafts (n = 6) were separated from the zygomatic arch; the remaining onlay bone grafts (n = 6) were left on the zygomatic arch. Three-point breaking strength was measured through the center of the graft/implant site on the zygomatic arch, followed by histologic evaluation and histometric assessment of residual bone density. The findings demonstrated no difference in the breaking strength per unit bone area between the control zygomatic arch group and the onlay group in which the bone graft was left in place. Breaking strength of the zygomatic arch in the former two groups was significantly greater than that in either group in which the onlay bone graft or implant had been removed, and was also greater than the breaking strength in that group in which inlay bone had been placed (p < 0.05). Histologic assessment showed full-thickness conversion in architecture of the zygomatic arch from compact to woven bone beneath onlays of either autogenous bone graft or steel implant; histometric assessment demonstrated an accompanying decrease in bone density in the latter groups relative to the control zygoma (p < 0.05). We conclude that onlay autogenous bone graft and alloplastic implants to the facial skeleton induce transformation of both graft and recipient bone from compact to woven architecture, accompanied by a reduction in bone density. The biomechanical strength of recipient facial bone is significantly weakened if an onlay bone graft or implant is removed. Weakening occurs per unit area of remaining bone, and is therefore independent of any thinning that may occur within the recipient bone because of graft/implant placement. These findings may impact upon decisions to augment stress-bearing regions of the facial skeleton with bone graft or implants, particularly if the graft/implant may eventually require removal.     

Acute rejection of porcine small bowel allograft. An extended histological scoring system

Using nonimmunosuppressed piglet small bowel grafts, we performed a detailed histological study on acute rejection and analyzed altogether 45 different histological parameters throughout the bowel wall, in 10 allografts and 6 autografts. Heterotopic grafts were followed by full-thickness biopsies every other day beginning on the 3rd day after transplantation. The parameters were scored from 0 to 3 according to the severity of the change and the values of every variable were compared statistically between the 2 groups. The earliest significant changes, beginning on days 3-5, were infiltration of inflammatory cells and pyroninophilia among these cells in lamina propria; edema, fibrosis, and inflammation in submucosa and muscularis; vacuolar degeneration of myocytes; and endothelial and intimal changes in vessels. Villous blunting and cuboidal epithelium were the other early markers. On day 7, the epithelial and vascular changes became most significant. We want to emphasize especially the vascular parameters: endothelial swelling and proliferation, intimal thickening, intramural inflammation, and obliteration of the lumen. The dilatation of lymph vessels and changes of Peyer's patches had no value in the estimation of rejection. All allografts became necrotic by day 11 after transplantation.     

Prognostic factors and therapeutic options of radiotherapy in pediatric brain stem gliomas

BACKGROUND: Calvarial bone graft is often used in reconstructive cranio-facial surgery. As most common three different forms can be distinguished: outer-table bone, full thickness grafts and composite flaps (bone with a periostal or muscular pedicle). PATIENT AND METHOD: An extensive fibrous dysplasia of the frontal region was removed in a 26 years old patient. Reconstruction was carried out with alloplastic material achieving a good esthetic result. Recurrent seroma and occurrence of a fistula demanded removal of the alloplastic material and en-bloc reconstruction of the forehead region was accomplished with a parietal outer-table graft. Within a follow-up time of one year a good esthetic and stable reconstruction has been achieved. CONCLUSION: Split-thickness calvarial bone is still a versatile graft in reconstruction of the forehead region. Although a low rate of side effects in harvesting calvarial bone grafts are in general expected, one has to be aware of dural lesions occuring in the donor site during craniotomy.     

Cryopreserved arterial allografts in the treatment of major vascular infection: a comparison with conventional surgical techniques

OBJECTIVE: Recent findings with cryopreserved heart valve allografts in the treatment of infectious endocarditis suggest that the use of cryopreserved arterial allografts may improve the outcome in patients with vascular infections. METHODS: Seventy-two patients with mycotic aneurysms (n = 29) or infected vascular prostheses (n = 43) of the thoracic (n = 26) or abdominal aorta (n = 46) were treated with in situ repair and extra-anatomic reconstruction using prosthetic material (n = 38) or implantation of a cryopreserved arterial allograft (n = 34). Disease-related survival and survival free of reoperation were assessed. Morbidity, cumulative lengths of intensive care, hospitalization, antibiotic treatment, and costs were calculated per year of follow-up. RESULTS: The use of cryopreserved arterial allografts was superior to conventional surgery in terms of disease-related survival (P =.008), disease-related survival free of reoperation (P =.0001), duration of intensive care per year of follow-up (median 1 vs 11 days; range 1 to 42 vs 2 to 120 days; P =.001), hospitalization (14 vs 30 days; range 7 to 150 vs 15 to 240 days; P =.002), duration of postoperative antibiotic therapy (21 vs 40 days; range 21 to 90 vs 60 to 365 days; P =.002), incidence of complications (24% vs 63%; P =.005), and elimination of infection (91% vs 53%; P =.001). In addition, costs were 40% lower in the group treated by allografts (P =.005). CONCLUSIONS: The use of cryopreserved arterial allografts is a more effective treatment for mycotic aneurysms and infected vascular prostheses than conventional surgical techniques.     

The use of arterial allografts in aortic graft infections. A three year experience on eighteen patients

BACKGROUND: We describe our experience in the treatment of aortic graft infections by replacing them with arterial homografts as suggested by the good results recently described. METHODS: Between March 1994 and March 1997 eighteen patients with infections of the aortofemoral bifurcation segments have been treated. All patients underwent a complete explantation of the infected graft and an in situ revascularization with arterial homograft harvested in multiorgan removal. Eight segments were freshly preserved, 10 were cryopreserved. Four patients were operated as emergencies, of which 3 for aorto-enteric fistulas. All others presented a serious septic state. RESULTS: Three patients died in the early postoperative period: one of acute infarction and two of homograft related causes. In the follow-up there was only one death from acute infarction, a branch occlusion and two allograft enteric fistulas successfully treated by surgery. All surviving patients are submitted to periodical haemodynamic and tomographic control with an average follow-up of 22 months (range 3 months to 3 years) and there has been no allograft degeneration so far. CONCLUSIONS: The use of homologue arterial allografts has shown good results in the treatment of serious aortic graft infections resulting in adequate peripheral vascularization. There have been no significant degenerations to date, either in fresh or cryopreserved allografts.     

Split calvarial graft cranioplasty for the prevention of headache after retrosigmoid resection of acoustic neuromas

OBJECTIVE: This study describes the technique and efficacy of split calvarial graft cranioplasty for the reconstruction of retrosigmoid/suboccipital defects following surgery for acoustic neuromas. STUDY DESIGN: A prospective study of the technique of split calvarial graft cranioplasty, its postoperative healing, and incidence of postoperative headache. METHODS: The technique requires splitting of the craniotomy bone flap into outer and inner table bone grafts. The combination of both bony grafts allows the coverage of a wider area of posterior fossa dura. This technique was used in 18 patients. All patients were followed for a minimum of 6 months. Eleven of 18 patients were followed for 1 year or longer. Four patients had three-dimensional computed tomography of their skull and area of split calvarial bone graft. RESULTS: One of 18 patients had a persistent disabling headache at 1 year postoperatively. A natural contour of the retrosigmoid area was achieved in all patients. Three-dimensional computed tomography scan, obtained 6 months postoperatively, showed total coverage of the retrosigmoid area and fusion of the bone flap to the surrounding skull. CONCLUSION: The technique of split calvarial grafting of posterior fossa defects is a feasible, safe, and effective way of separating the nuchal musculature and posterior fossa dura. The technique also allows the restoration of the contour and bony covering of the retrosigmoid area. The technique is a simple alternative to other types of cranioplasties aimed at reducing the incidence of postoperative headache in patients with acoustic neuromas.