Forearm reconstruction with bone allograft following tumor excision: a series of 10 patients with a mean follow-up of 10 years

BACKGROUND

After a tumor resection, the reestablishment of the bone continuity at the forearm remains a challenge for restoring the biomechanics of hand and elbow. Bone allograft might be one option to consider amongst other suitable alternatives but there are insufficient data available to substantiate its value.

PATIENTS AND METHODS

We retrospectively investigated a series of 10 consecutive patients that had presented a bone tumor at the forearm. After bone excision, the segmental loss was replaced either by a bone allograft or an osteochondral allograft. Patients were reviewed clinically and with radiographs.

RESULTS

The mean follow-up was 110 ± 99 months. Fracture of the allograft was the most prevalent complication occurring in four patients, mainly in the osteoarticular group. Four patients were surgically revised: two of them had a fracture of the allograft that required a new one, another one had a painful stiff wrist requiring removal of the allograft and arthrodesis with autograft and the fourth one had a non-union of an intercalary allograft that was treated by a distal ulnar joint resection. Intercalary allograft had fewer complications than osteoarticular allografts and they had a better functional MSTS score with an average of 79% of a normal function compared to osteoarticular allografts with an average score of 62%. There was no infection. At the latest follow-up, one reconstruction of the forearm with an allograft failed and concerned the distal radius joint.

DISCUSSION

A bone allograft when available can be considered as one amongst other suitable options for the reconstruction of the forearm skeleton.

[Is there still a place for bone allografts in orthopedic surgery in 2011?]

The place of bone allograft in contemporary orthopaedic surgery is discussed. Bone allograft can be prepared from retrieved femoral heads for fracture or osteoarthritis and are used as a filling material. Demineralized bone matrix is a cortical bone that has been exposed to a demineralizing solution. Doing so, the growth factors of the bone are exposed and will be able to induce the formation of new bone cells from the host. This osteoinductive capacity makes the graft more active in the process of its incorporation and has been successfully used in the conservative treatment of aneurismal bone cysts. Massive bone allografts can be used as a full segment of a long bone to reconstruct part of the skeleton either alone with fixation or with a prosthetic device. Except demineralized bone, any other types of bone allograft serve as a biologic passive support for the migrating cells from the host. Cellular therapy is another approach that allows, considering the extensive use of in vitro expanded bone, forming cells originating either from the bone marrow or the fat tissue of the patient. However, this approach needs further clinical validation before being fully considered in patient.

Human tissue allograft processing: impact on in vitro and in vivo biocompatibility

This work investigates the impact of chemical and physical treatments on biocompatibility for human bone/tendon tissues. Nontreated and treated tissues were compared. In vitro testing assessed indirect and direct cytotoxicity. Tissues were subcutaneously implanted in rats to assess the immunological, recolonization, and revascularization processes at 2-4 weeks postimplantation. No significant cytotoxicity was found for freeze-dried treated bones and tendons in comparison to control. The cellular adhesion was significantly reduced for cells seeded on these treated tissues after 24 h of direct contact. A significant cytotoxicity was found for frozen treated bones in comparison to freeze-dried treated bones. Tissue remodeling with graft stability, no harmful inflammation, and neo-vascularization was observed for freeze-dried chemically treated bones and tendons. Frozen-treated bones were characterized by a lack of matrix recolonization at 4 weeks postimplantation. In conclusion, chemical processing with freeze-drying of human tissues maintains in vitro biocompatibility and in vivo tissue remodeling for clinical application.

Bone allografts: What they can offer and what they cannot

Bone allografts can be used in any kind of surgery involving bone from minor defects to major bone loss after tumour resection. This review describes the various types of bone grafts and the current knowledge on bone allografts, from procurement and preparation to implantation. The surgical conditions for optimising the incorporation of bone are outlined, and surgeon expectations from a bone allograft discussed.

Reconstruction du coude par allogreffe massive ostéo-articulaire totale : échec précoce par instabilité

Total elbow allografts were implanted for the treatment of trauma-induced bone defects in three patients between 1986 and 1990. Six allografts were implanted and finally explanted. The longest follow-up for an implanted allograft was five years. Allografts had to be removed because of nonunion in one patient and gross instability in the others. A constrained elbow prosthesis was implanted in all three patients. This short series illustrates mid-term failure to be expected with total elbow allografts, mainly due to instability. Accordingly, we no longer recommend the use of total elbow allografts alone as a salvage procedure for bony defects. If an allograft is needed, it should be implanted with a prosthesis.

How to improve the incorporation of massive allografts?

The incorporation of a bone graft is the result of creeping and substitutional activities that remove the original grafted bone and replace it by newly formed bone from the host cells. However, this intricate process is very limited in time and space. A bone allograft is poorly remodeled and is almost non viable even after several years of implantation. This lack of vitality accounts for the high rate of complications such as non union and fracture. One way to minimize the allograft complications is to improve its incorporation. The process of incorporation in animals and human beings is reviewed as well as the various avenues for a biologic improvement either through modulation on the host: the immune response, the inhibition of bone resorption, the use of bone morphogenetic proteins, the autogenous cell augmentation or through processing the bone allograft: bisphosphonate adsorption or bone perforations. In 2002, biologic enhancement of the incorporation is still in its infancy but will be in a near future a reality through influence on both the host and the allograft.

Irreversible perforations in vertebral trabeculae?

In human cancellous bone, osteoclastic perforations resulting from normal remodeling were generally considered irreversible. In human vertebral samples, examined by backscatter electron microscopy, there was clear evidence of bridging of perforation defects by new bone formation. Hence trabecular perforations may not be irreversible.

INTRODUCTION

Preservation of the trabecular bone microarchitecture is essential to maintain its load-bearing capacity and prevent fractures. However, during bone remodeling, the osteoclasts may perforate the platelike trabeculae and disconnect the structure. Large perforations (>100 microm) are generally considered irreversible because there is no surface on which new bone can be laid down. In this work, we investigated the outcome of these perforations on human vertebral cancellous bone.

MATERIALS AND METHODS

Using backscatter electron microscopy, we analyzed 264 vertebral bone samples from the thoracic and lumbar spine of nine subjects (44-88 years old). Nine fields (2 x 1.5 mm) were observed on each block. Several bone structural units (BSUs) were visible on a single trabecula, illustrating a dynamic, historical aspect of bone remodeling. A bridge was defined as a single and recent BSU connecting two segments of trabeculae previously separated by osteoclastic resorption. They were counted and measured (length and breadth, microm).

RESULTS AND CONCLUSION

We observed 396 bridges over 2376 images. By comparison, we found only 15 microcalluses on the same material. The median length of the bridge was 165 microm (range, 29-869 microm); 86% being longer than 100 microm and 35% longer than 200 microm. Their breadth was 56 microm (range, 6-255 microm), but the thinnest were still in construction. Bridges were found in all nine subjects included in the study, suggesting that it is a common feature of normal vertebral bone remodeling. These observations support the hypothesis that perforation could be repaired by new bone formation, and hence, might not be systematically irreversible.

Bone substitutes in 2003: an overview

The authors review the various bone substitutes which are currently available on the market place in Belgium. After describing the requirements for clinical use of such materials, they compare the biological and mechanical values of bone autografts, bone allografts, demineralised bone, xenografts, coral and synthetic materials such as calcium sulfate, calcium phosphate, ionic cement and bioactive glass. They stress the current paucity of data pertaining to the biological value of these materials and call for in vivo validation tests. They also review biomolecules such as BMP-2 or OP-1, whose osteoinductive properties are currently under investigation. Finally, they present the emergent field of cell therapy, in which osteoprogenitor cells are isolated from the patient's bone marrow and reinjected after in vitro cultivation. They stress the therapeutic and medicolegal problems raised by the combination of medical devices, grafts, medicinal products and cells, all of which have a different status within the complex European legal framework.

Indirect cytotoxicity evaluation of pseudowollastonite

This study aimed to evaluate the cytotoxicity of substances leached by pseudowollastonite (CaSiO(3)). It has been previously shown that calcium (Ca(2+)) and silicate (SiO(3)(-)) ions are released from pseudowollastonite into biological solutions. Both of these ions are known to influence the biological metabolism of osteoblastic cells essential in the mineralization process and bone-bonding mechanism. The indirect toxicity evaluation was performed by extraction method, according to International Standard Organization (ISO). Pseudowollastonite pellets obtained by solid-state reaction were incubated, in culture medium, during 24, 48, 72 or 168 h at different concentrations (5, 10, 15, 50, 100, 200 mg/ml). The cytotoxicity of each extract in presence of human osteoblastic cell line (SaOS-2) was quantitatively assessed by measuring the viability (succinate dehydrogenase activity, MTT), the membrane integrity (the uptake of the neutral red by viable cells, NR) as well as the cell necrosis by measuring the lactate dehydrogenase (LDH) released in the culture medium. No significant alteration of membrane integrity or cell suffering was detectable. However, increased cell metabolism was observed for cells exposed to pseudowollastonite extract with longest extraction time (168 h). In conclusion, mineral elements leached by pseudowollastonite do not significantly affect the metabolism of osteoblastic cells.

[Bone grafts using tissue engineering]

An overview of bone grafts and, in particular, the allografts is presented. The availability of bone allografts, has promoted their use at the expense of the autograft. However, the loss of the cellular activity in an allograft, makes them less performant than an autograft. The use of an allograft in a small size defect can be advocated provided that the implantation technique is stringent. In case of a large segmental bone defect, an allograft can be considered whereas an autograft is not anymore possible. A massive bone allograft allows an anatomical reconstruction and the preservation of strong tendon insertions. In tumor surgery, a bone allograft has become one of the best options to reshape the skeleton. To offset the poor remodeling of the massive bone allografts, and to improve the take of small size bone allografts, researches are presently carried on, using tissue engineering in order to recover a cellular population. The aim is to combine an acellular bone graft with the cells of the recipient. Cells are procured from the bone marrow. Stromal cells are isolated, cultured, so that they will grow with an osteoblastic phenotype. They can be used alone or in association with a bone graft. It is believed that tomorrow such cellular therapy will become a routine procedure.

Physical and chemical processing for a human dura mater substitute

OBJECT

Allogenic human fascia lata used in neurosurgery, as dura mater substitute, can be associated with a risk of viral and bacterial transmission. Chemical and physical procedures, developed to inactivate virus and bacteria, have been applied to fascia lata. The aim of this study consists in the evaluation of the biological properties of this treated graft.

METHODS

Grafts were treated with solvent detergents, freeze-dried for conservation and gamma irradiated (25,000 Gy) for sterilization. The indirect toxicity evaluation was performed by extraction method, according to the International Standard Organization (ISO). First, the cytotoxic effect of each extracts incubated in the presence of human fibroblasts (WI38) was quantitatively assessed by measuring the cell growth, the viability (succinate dehydrogenase activity, MTT), the membrane integrity (uptake of the neutral red by viable cells, NR) as well as the release of lactate dehydrogenase in the culture medium. Second, confocal laser scanning microscopy (CLSM) was used to assess the direct contact between human primary fibroblasts and graft. CLSM was performed at days 3 and 7 after cells loading.

RESULTS

No acute cytotoxicity was observed for chemically processed allografts. Cells loaded on the graft have demonstrated a good growth and spreading.

CONCLUSIONS

Human fascia lata secured against conventional and non-conventional agents is a fully biocompatible alternative to the available dural graft materials.

[Mechanical complications of total shoulder inverted prosthesis]

Our series of inverted prosthesis included 5 patients with a mean age of 73 +/- 6 years. In 4 cases, the implant was performed as a surgical revision. The follow up was 81 +/- 15 months. Three shoulders were pain free whereas two caused a dull pain after a free interval due to mechanical complications. The mean active elevation was 72 degrees while external rotation was - 2 degrees. The adjusted Constant score passed from 32 to 60. In case of complications, the score dropped to 32. Mechanical complications were important with in one case, an unscrening of the glenosphere and in two cases, a loosening of the glenoid prosthesis. This last and major complication occurred 6 years after surgery and was promoted by the occurrence of a progressive bone erosion in the scapula. This gap represented an attempt to accomodate the medial part of the humeral prosthesis under the scapula when the arm is at rest or in adduction. The concept of an inverted prosthesis is attractive and this implant remains one of the options in cuff-tear arthropathy. Our results were not as good as those reported by others but most of ours patients had been already operated before. The occurrence of an osseous gap on pilar of scapula may lead to failure of this prosthesis. This gap remains a threath as it can progress and as such warrants a design alteration of the prosthesis.

Stiffness and compactness of morselized grafts during impaction: an in vitro study with human femoral heads

The mechanical properties of the impacted material is important when using impaction bone grafting in revision arthroplasty. We did an in vitro study to monitor the stiffness and compactness of morsellized bone grafts during impaction. Using human osteoarthrotic femoral heads as the bone source we prepared 3 types of morselized grafts with the same bone mill: (1) purely cancellous grafts, (2) cortico-cancellous grafts and (3) cortico-cancellous bone with cartilage remnants. 5 g of bone samples were progressively impacted up to 150 times in a contained cavity. All types of grafts became stiffer and stiffer during the first 30 impactions. After 30 impactions, the grafts' compactness continued to increase slowly without concomitant changes in their stiffness. Over-impaction was not useful, but did not jeopardize the implant stability. The presence of cartilage remnants considerably compromised the increase in stiffness. In contrast, the addition of cortical bone from the femoral neck did not affect the impaction and resultant stiffness.

Inhomogeneity of human vertebral cancellous bone: systematic density and structure patterns inside the vertebral body

In the spine, cancellous bone quality is usually assessed for the whole vertebral body in a transverse central slice. Correct identification and assessment of the weakest parts of the cancellous bone may lead to better prediction of fracture risk. The density and structural parameters were systematically investigated inside the thoracic (T-9), thoracolumbar (T12-L1), and lumbar (L-4) vertebral bodies of nine subjects. On both sides of the median sagittal plane, anterior and posterior 8.2 mm vertical cores were harvested in the thoracic vertebra. In the thoracolumbar and lumbar vertebrae, external samples were also cored. Peripheral quantitative computed tomographic (pQCT) density analysis of the 136 cores was performed at four different levels, from the lower to the upper endplate. The relatively thin slice thickness (300 microm) and small pixel size (70 microm x 70 microm) was considered sufficient to investigate the structural parameters on the four transverse slices and in the sagittal and coronal planes (total of 816 images). Using a constant threshold a binary image was generated and the morphometric data were extracted. The binary image was further skeletonized and classical strut analysis was performed. Cancellous bone density was 20% higher in the posterior cores than in the anterior and external cores. Moreover, clear vertical inhomogeneity was noted because the lowest half of the vertebral body presented lower density than the upper half (differences ranging from 25% to 15%). All structural parameters were strongly dependent on the location of the measurement. Structural differences between anterior, posterior, and external areas were mild and followed the density patterns. On the other hand, vertical inhomogeneity of the structural parameters was important. For example, in the thoracolumbar and lumbar vertebrae, the numbers of nodes or node-to-node struts were almost twofold higher in the inferior half than in the superior half (p < 0.01), whereas trabecular thickness and number of free-ends presented a center/close-to-endplate structural pattern, with central trabeculae being 15% thicker (p < 0.05) and presenting 30% fewer free-ends (p < 0.01) than the close-to-endplate ones. Variability of density and structural parameters was high and a substantial part of this variability could be explained by the place inside the vertebral body where the measurement was made. The weak part was not in the center of the body but in its upper half where the lower density did not seem to be compensated by a higher structural architecture. Further clinical investigation could enhance fracture prediction by tracking and focusing on the weakest part of the vertebral body.

In vitro evaluation of acute cytotoxicity of human chemically treated allografts

In order to minimize the risk of contamination associated with tissue transplantation, tissue banks commonly chemically treat the tissues whenever possible. As viral inactivation uses agents lethal to microorganisms, it is imperative to assure that chemically inactivated tissue remains biocompatible. In vitro assays can be an effective means to assess the acute cytotoxicity of chemically treated human allografts. We have used different types of cells cultured in the presence of treated tissue extract. A standard cell line, a human fibroblast (WI38), which was the same for all the samples, was chosen. In addition, as the banked tissues (bone and fascia lata) were prepared to be used in bone or as a dura mater substitute, two other cell types were also used: an osteoblastic cell line (SaOS-2) and a neuronal cell line (Neuro 2A). Cytotoxic assessment was performed by qualitative evaluation of cell morphology based on confluence, granulation, vacuolization and swelling analysis. In addition, quantitative methods based on the use of neutral red (NR) and 3- (4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) were assayed. Qualitative and quantitative evaluation of fascia lata and bone extracts did not show deleterious effects on cell cultures. These results show that in vitro methods can be appropriate to select a non-toxic procedure before it is used in the human body and that several strong chemical treatments can result in a tissue suitable for human.

Effect of freeze-drying and gamma irradiation on the mechanical properties of human cancellous bone

Freeze-drying and gamma irradiation are commonly used for preservation and sterilization in bone banking. The cumulative effects of preparation and sterilization of cancellous graft material have not been adequately studied, despite the clinical importance of graft material in orthopaedic surgery. Taking benefit from the symmetry of the left and right femoral heads, the influence of lipid extraction followed by freeze-drying of a femoral head and a final 25-kGy gamma irradiation was determined, with the nonirradiated, nonprocessed counterpart as the control. Five hundred and fifty-six compression tests were performed (137 pairs for the first treatment and 141 pairs for the second). Mechanical tests were performed after 30 minutes of rehydration in saline solution. Freeze-dried femoral heads that had undergone lipid extraction experienced reductions of 18.9 and 20.2% in ultimate strength and stiffness, respectively. Unexpectedly, the work to failure did not decrease after this treatment. The addition of gamma irradiation resulted in a mean drop of 42.5% in ultimate strength. Stiffness of the processed bone was not modified by the final irradiation, with an insignificant drop of 24%, whereas work to failure was reduced by a mean of 71.8%. Freeze-dried bone was a bit less strong and stiff than its frozen control. Its work to failure was not reduced, due to more deformation in the nonlinear domain, and it was not brittle after 30 minutes of rehydration. Final irradiation of the freeze-dried bone weakened its mechanical resistance, namely by the loss of its capacity to absorb the energy (in a plastic way) and a subsequent greater brittleness.

Cortical bone allografting in femoral head necrosis

Ten femoral heads (six patients) with avascular necrosis were operated on using a fibular allograft. The procedure included core decompression followed by insertion of a cortical bone graft in order to relieve mechanical stresses from the overlying subchondral bone. The presence of the supporting graft should avoid an expected collapse or prevent its worsening if already present. A freeze-dried and processed cortical bone allograft was preferred to an autograft. Weightbearing was normally and fully resumed at the second postoperative month. There were three failures within the first year, four satisfactory results, in which the hip was replaced after 4 years while there are still 3 hips that have been preserved from arthroplasty in young patients after 5 years. The technique is easy and able to substantially delay an arthroplasty in an active patient.

Ethanol treatment of tendon allografts: a potential HIV inactivating procedure

The penetration rate of ethanol in human tendons was studied to in order to define the conditions which were necessary to achieve an inactivating concentration against the Human Immunodeficiency Virus (HIV) within the tendon. The rate of alcohol penetration was found to be slow and did not differ with different types of tendons. An average ethanol concentration of 14% (v/v) was measured in human tendons after they had been immersed for 2 h in 70% (v/v) ethanol, and a concentration of 19% (v/v) was reached after 3 h. Ethanol immersion of human tendons may represent an additional safety procedure in inactivating the HIV virus provided the duration is at least 3 h.

Simple bone cysts treated with aspiration and a single bone marrow injection. A preliminary report

The results of a single percutaneous aspiration and injection of marrow into active, simple bone cysts are reported in 8 cases. Slow regression of the cyst was consistently observed except in one lesion in the distal tibia. All the patients have been free of symptoms after this treatment after a mean follow up of 31 months. The evolution of the cysts was monitored by a cyst index, cyst diameter measurements and computer assisted densitometric image analysis of serial radiographs.

Digital image analysis of bone allograft union in sheep

We compared the reliability of computer-assisted radiographic analysis (CARA) and visual evaluation of radiographs to assess host-graft junctions. 68 host bone/allograft junctions were obtained from an ongoing study on bone allografting in sheep. At 6 months, the grafted tibias were explanted and healing of the host-graft junctions were macroscopically determined. 49 junctions were macroscopically healed, whereas 19 had not united. 51 (0.8) of the junctions were correctly classified by radiographs, while 63 (0.9) of the junctions were correctly classified by CARA (p = 0.03). These findings warrant further evaluation in a clinical setting.

Antibiotic-loaded plaster of Paris implants coated with poly lactide-co-glycolide as a controlled release delivery system for the treatment of bone infections

Plaster of Paris implants containing vancomycin (60 mg/g of carrier) were prepared in order to be used as local delivery system for the treatment of bone infections. The regulation of the release rate was performed by coating the carrier with a polylactide-co-glycolide polymer composed by 10% (w/w) polyglycolic acid and 90% (w/w) racemic poly (D,L-lactic acid). The release of the antibiotic from the biodegradable matrix was evaluated in vitro. From this investigation, it is clear that the drug elution depends on the coating depth. After a burst effect occurring on the first day of the experiment, therapeutic concentrations were measured during one week when uncoated implants were used. The coating allowed decrease of the burst effect and extended efficient release to more than five weeks when the implants were embedded with six layers (162 microns) of PLA45GA10. This delivery system was implanted into the femoral condyle of rabbits. It was shown that the in vivo release was also closely regulated by the coating depth. In all bone tissues (bone marrow and cortical bone) surrounding the pellets, the drug concentration exceeded the Minimum Inhibitory Concentration for the common causative organisms of bone infections (Staphylococcus aureus) for at least four weeks without inducing serum toxic levels. Due to its cheapness, facility of use and sterilization, biocompatibility and biodegradability, plaster of Paris coated with PLA45GA10 polymer giving a controlled release of vancomycin appears to be a promising sustained release delivery system of antibiotics for the treatment of bone and joint infections.

Ethylene oxide does not extinguish the osteoinductive capacity of demineralized bone. A reappraisal in rats

We examined the influence of ethylene oxide (EO) and gamma irradiation on the osteoinductive capacity of demineralized bone. Demineralized bone powder prepared from Wistar rats was exposed to EO (55 degrees C or 40 degrees C) or gamma irradiation (25 KGy) or was preserved in ethanol. Sterilely-prepared bones served as controls. The powder was packed in a gelatin capsule and implanted for 6 weeks in muscles of 6-week-old female rats. Exposure of demineralized bone particles to EO 55 degrees C resulted in an almost complete loss of osteoinductivity. Irradiated bones lost about 40% of their osteoinductive capacity, while sterilization with EO at 40 degrees C resulted in only a slight alteration of the osteoinductivity, as assessed by the recovered weight ratio, calcium content, alkaline phosphatase activity measurements and histomorphometry. Ethanol treatment had no influence on the new bone yield when compared to controls. As EO exposure at 40 degrees C is a true sterilization procedure, it can be recommended in a clinical setting for its small effect on osteoinductive capacity as assessed experimentally in rats.

Comparative left-right mechanical testing of cancellous bone from normal femoral heads

In order to assess the potential influence of various physical or chemical treatments on bone grafts, and in particular, on femoral heads to be used as bone grafts, the mechanical symmetry of the femoral head was investigated. Pairs of proximal human femora were harvested and transversally sliced using a coordinate system to orient correctly the head. After being embedded and polished, bone slices were loaded to failure between two steel columns (6 mm of diameter) in a sequential and symmetrical manner for both heads. From ten pairs, 592 mechanical assays on the cancellous bone of femoral heads were performed. There was a high variation in the mechanical properties of the specimens from the different donors. However, no statistical difference could be observed within each pair when side-to-side symmetry was tested for the different mechanical characteristics. Ultimate stress at failure and stiffness were also highly correlated for each mirror location of each pair. Provided that an accurate and reproducible method of slicing femoral head can be achieved, an excellent mechanical symmetry is observed using a static compressive test. Such a method could be used to determine the mechanical influence of any treatment applied to bone.

Induced healing of aneurysmal bone cysts by demineralized bone particles. A report of two cases

Two cases of induced healing of aneurysmal bone cyst (ABC) following intralesional implantation of a bone paste made of autogeneic bone marrow and allogeneic bone powder are reported. The calcaneum in one case and the superior pubic ramus in the other were blown out by an ABC and would have required extensive surgery. Via a minimal exposure, the cyst was partially evacuated and filled with an admixture of a partially demineralized bone particles with bone marrow. Ossification of the peripheral shell was the first sign of healing and was observed within the first 3 postoperative months. Successful healing was observed in both cases. The rationale underlying this intralesional treatment was that the bone grafting material might reverse ABC expansion by promoting ossification through a bone induction mechanism. The concept of this treatment was to retain the ABC tissue, using its own intrinsic osteogenic potential to promote healing. By triggering intralesional new bone formation, the bone paste represented an effective means to reverse the expanding phase of ABC. The particulated bone allograft was easy to handle and to introduced in an irregular cavity. Moreover, as a complete cyst evacuation was not required, a minimal surgical approach could be used so that the risks and morbidity associated with an extensive approach were reduced. Its use is of particular interest in poorly accessible areas like the pelvis and spine.

Biodegradable implants for potential use in bone infection. An in vitro study of antibiotic-loaded calcium sulphate

Local antibiotic therapy by diffusion from plaster of Paris beads has proved promising in bone surgery. Sustained local delivery depends on thermostability, so we tested the antibacterial activity of 11 antibiotic solutions after storage at 37 degrees C using a microbiological method. Cephalosporins and penicillins were unstable, but aminoglycosides remained fully stable with 100% activity after 2 weeks. About 60% of the initial bactericidal activity of quinolone, glycopeptides and sodium fusidate were still detectable after 2 weeks. Release of these antibiotics from plaster of Paris beads was evaluated in vitro. Even those in the same family differed in their release rate. Plaster beads with sodium fusidate were the most effective association. A therapeutic level of glycopeptides, aminoglycosides and amoxicillin was leached for about 3 weeks. Cephalosporins and sodium amoxicillin were released in 2 to 3 days, and quinolone beads were too brittle to be used. Plaster of Paris, which is cheap, biocompatible and biodegradable, is an excellent carrier for sodium fusidate, aminoglycosides and glycopeptides.

Tibial tubercle elevation with bone grafts. A comparative study of autograft and allograft

We retrospectively investigated the fate of bone auto- and allografts in 64 patients who underwent a tibial tubercle elevation with bone graft. Half of them received an autograft and the other half, an allograft that had been processed and freeze-dried. The two groups had similar preoperative characteristics concerning age, sex and pathology. Roentgenograms were reviewed by three independent observers and scored for fusion, resorption and collapse. Clinical charts were analysed for different variables. The overall radiological score for both groups did not differ statistically. Comparison of graft fixation with one or two screws demonstrated more bone resorption in the case of a single-screw fixation. In such a case, the occurrence of a preoperative tubercle fracture had a significant adverse influence, due to a less stable fixation. From the clinical charts review, only the mean stay at hospital was significantly shorter when an allograft was performed. A bone allograft appears to be suitable to maintain an osteotomy but requires a more careful surgical technique fixation to obtain a similar result to an autograft.

[Multiple perforation in cryogenically preserved bone allografts. Comparative histological and microradiographic study of perforated and non-perforated allograft in sheep]

Incorporation of massive cortical bone allografts in the human is slow and remains incomplete. Late biopsies of implanted allografts or histological studies of explanted allografts always show the partial substitution of necrotic bone by new bone from the host. The aim of the present study was to evaluate the value of drilling the massive deep-frozen cortical allografts in order to induce osteogenesis. Thirteen sheep were operated on and a standard segment of the proximal ulna was removed and the gap filled either by an unperforated allograft or by a perforated one. Based on histological and microradiographic examination, a complete substitution of the perforated allografts was observed but in this model no statistically significant difference was observed between perforated and unperforated allografts. Further study is needed to assess the effect of the perforations.

Morphometric and physical investigations of segmental cortical bone autografts and allografts in canine ulnar defects

Cortical bone grafts were implanted for six months in mature dogs using an osteoperiosteal 3-cm defect in the ulna to evaluate their respective morphometric and physical values compared with autografts. The bone-grafting material included fresh auto- and allografts, frozen and thimerosal preserved allografts, and partially demineralized bone allografts. The grafts were evaluated by roentgenograms, microradiograms, photon absorptiometry, porosity, fluorescence labeling measurements, and torsional loading at failure. Autografts achieved a better union score than the allografts, but intracortical bone porosity, percentage of cumulative new bone, and mineral apposition rate were not variables with statistical significance. Lamellar bone was found earlier and in greater quantity in autografts. Within the graft, new bone was deposited at a slower rate than in the recipient bone. Autografts showed less peripheral resorption and a greater torsional resistance than allografts. Photon absorptiometry demonstrated that nondemineralized allografts underwent a substantial loss of peripheral bone. This marked reduction in the outer diameter of the graft had more influence on torsional resistance than did the intracortical porosity of the graft. Demineralized allografts were osteoinductive in only 28% of the cases and appeared to respond in an all-or-nothing pattern. Frozen and thimerosal preserved allografts were the most acceptable substitutes to autografts.

Bone regenerate formation in cortical bone during distraction lengthening. An experimental study

The aim of this study was to delineate the pattern of bone regeneration from cortical bone segments during distraction lengthening. The lengthening procedure was applied for various periods through the Ilizarov system on the forearms of mature dogs. Bone was sectioned either by corticotomy, preserving the nutrient artery integrity, or by osteotomy. When an osteotomy was performed, the marrow cavity was in some cases plugged with either resorbable bone wax or nonresorbable material. Under distraction, both periosteal and medullary callus on either side of the gap gave rise to new bone trabeculae. The trabeculae on either side were oriented along the direction of distraction and progressively approached one another. This striated callus emerging from both sides was the most characteristic pattern of bone regeneration subsequent to distraction lengthening. Fusion was achieved approximately four weeks after the end of the lengthening period. Most of the new bone was formed by membranous ossification; some cartilaginous nodules developed. Corticalization of the bone trabeculae that had begun at three months was not fully achieved at five months after the lengthening period. There were no differences found in the pattern of bone healing and the amount of newly formed bone after corticotomy or osteotomy with or without resorbable bone wax plugging.

Bone sialoprotein II synthesized by cultured osteoblasts contains tyrosine sulfate

Isolated mouse osteoblasts that retain their osteogenic activity in culture were incubated with [35S] sulfate. Two radiolabeled proteins, in addition to proteoglycans, were extracted from the calcified matrix of osteoblast cultures. All the sulfate label in both proteins was in the form of tyrosine sulfate as assessed by amino acid analysis and thin layer chromatography following alkaline hydrolysis. The elution behavior on DEAE-Sephacel of the major sulfated protein and the apparent Mr on sodium dodecyl sulfate gels were characteristic of bone sialoprotein II extracted from rat. This protein was shown to cross-react with an antiserum raised against bovine bone sialoprotein II, indicating that bone sialoprotein II synthesized by cultured mouse osteoblasts is a tyrosine-sulfated protein. The minor sulfated protein was tentatively identified as bone sialoprotein I or osteopontin based on its elution properties on DEAE-Sephacel and anomalous behavior on sodium dodecyl sulfate gels similar to those reported for rat bone sialoprotein I.

Freeze-dried bank bone

The authors present their experience with freeze-dried bone of human origin. Since 1983, 500 preserved allografts have been implanted in 228 patients. The implants were monitored radiographically and, based on perfect fusion with the recipient bone, the results were as follows: excellent: 78%; good: 8.6%; failure: 12.4%. In nearly all the cases of failure this was attributed to an erronous implant method or an improper use of the graft. Bank bone is only osteoconductive: thus, in the absence of osteogenetic properties, a perfect method of implant and its correct use are essential.

Bone allografts in reconstructive middle ear surgery

The authors present their current experience with stored bone grafts, using allografts shaped from the cortices of long bones for reconstructing the tympano-ossicular chain. The materials and the methods are described. The anatomical results have been good in 97% of the cases, while the functional results are as satisfactory as those obtained with bioceramics. In addition to ossiculoplasty, the bone allografts can also be used in otology for reconstructing large bony defects of the temporal bone.

Effect of sterilization on osteoinduction. Comparison of five methods in demineralized rat bone

The aim of this study was to find a safe, effective sterilization method that does not destroy the bone-inductive capacity of demineralized bone implants. Five sterilizing agents were tested in rats. Implants procured and processed under sterile conditions served as controls. New bone formation was evaluated by determining dry weight, calcium content, and Sr-85 incorporation of the induced ossicles. Glutaraldehyde solution, formaldehyde gas, and ethylene oxide destroyed almost all the bone-inductive capacity. Irradiation by 2.5 Mrads Co-60 resulted in a loss of about half of the inductive capacity. Merthiolate (0.18 per cent) was the only sterilizing agent that did not reduce the bone-inductive capacity of the demineralized implants. Because merthiolate is not sporicidal, gamma irradiation appears to be the most appropriate sterilizing agent for demineralized bone in clinical use.

Massive bone allografts in large skeletal defects after tumor surgery: a clinical and microradiographic evaluation

Massive deep-frozen bone allografts were implanted in 13 patients after en bloc tumor resection. Patients were followed up for 14 months to 17 years. Most of the reconstructive procedures included a segmental bone allograft with knee or ankle fusion. Graft infections were the most critical complications in regard to the end results, finally requiring amputation in two cases. There were three stress fractures; two of which were successfully treated without further complication. Graft incorporation was assessed by bone scintimetry in four cases. Isotope uptake by the center of the graft was found to be superior to control bone segments at only 15 years after surgery. Two recovered allograft specimens were available for a microradiographic study. Creeping substitution was a very slow process, initiated at the outer surface of the graft and characterized at 2-3 years after implantation by large, incompletely filled osteons. The present investigation demonstrates that massive bone allografts are very slowly revascularized and are intimately anchored by the host bone. Provided that tumor control is effective and graft infection is avoided, reconstructive surgery with massive bone allografts represents a successful alternative to prosthetic implants in young adult with a long life expectancy.

Bone injury and late giant-cell tumor occurrence: a possible relation. A case report

A giant-cell tumor of the upper end of the fibula, five years after a documented bone injury at the same site is reported. The histologic diagnosis was corroborated by the patient's age, tumor localization, radiologic and pathologic aspects. The role of a bone injury as a promoting factor in the development of this tumor is discussed. The tumoral occurrence as a reactive process to trauma in this case may not be ruled out.

Canine cortical bone autograft remodeling in two simultaneous skeletal sites

The morphological and physical aspects of cortical bone autografts implanted in dogs for 1-9 months in two differently located skeletal defects are reported with a twofold aim: to provide a reference system for further comparison with various allografts and to delineate a general pattern of cortical bone graft healing. A 3-cm osteoperiosteal gap was created in the diaphyseal segment of the ulna and fibula of mature dogs. The grafts, freed from periosteum and bone marrow, were then inverted and replaced for the autografts in the left limb bone without internal fixation or external splints. On the right side, different allografts were tested. A group of three animals also had an unfilled segmental resection on the right as control. Dogs were observed for 1, 2, 3, 6, and 9 months and were able to bear weight within 3 days. Twenty-eight ulnae and 27 fibulae were available for this autograft study. Fluorochromes were injected at mid-term and at the end of the observation. All the grafts were assessed morphologically by cross-section microradiographs and ultraviolet light microscopy, and a morphometric analysis for porosity and fluorescence was done. To evaluate the physical aspects of graft healing, the recovered ulnar autografts, when available, were submitted to photon absorptiometry and to torsional loading. Morphologically, resorption was found to invade the cortical bone graft transversely through radial tunnels, and in addition to the host-bone-graft junction, the entire transplant surface provided another way for revascularization. The highest porosity level was achieved 2 months after surgery for both ulna and fibula, while new bone formation, as assessed by fluorochromes, was most important at 3 months. At 9 months, porosity remained above the normal range as determined in a set of five nongrafted dogs. While the lack of correlation for porosity between the two grafts suggests that local factors are more important in graft resorption, the observed correlation for fluorescence indicates that new bone deposition is more dependent upon skeletal metabolic activity. Within each graft, porosity and new bone formation were not well correlated. In the ulna, the bone mineral content (BMC) reflected the graft volumetric variations during the remodeling, with the lowest mean value at 3 months. For each graft, BMC was well correlated with the torsional stiffness. When torsionally loaded, the maximal tangential shear stress at failure of the graft was negatively related to its cortical porosity.(ABSTRACT TRUNCATED AT 400 WORDS)

The osteoinductive capacity of differently HCl-decalcified bone alloimplants

Three procedures to obtain bone inductive implants were tested heterotopically in 3-month-old allogeneic rats: 1) antigen-extracted HCl-decalcified at 4 degrees C, autolysed implant (AAA bone); 2) HCl-decalcified implant at 4 degrees C; 3) HCl-decalcified implant at room temperature. Each type of implant was either deep-frozen at -35 degrees C for at least 2 months or immediately freeze-dried. The bone inductive capacity of the differently HCl-decalcified cortical bone implant was evaluated at 2 months by isotopic strontium incorporation and by ash-weight measurements. Bone HCl-decalcification alone, either at 4 degrees C or at room temperature, gave a higher new bone yield than the freeze-dried AAA bone. The type or short-term preservation technique had no effect on the osteoinductive capacity of either of the differently treated implants, AAA bone expected.

The effect of phenylbutazone on acute hemorrhagic pancreatitis in the rat

The effect of phenylbutazone on acute experimental pancreatitis was investigated in the rat. Severe necrotico-hemorrhagic pancreatitis was produced by intraductal injection of trypsin. Pretreatment by phenylbutazone did not alter the mortality rate but reduced the severity of pancreatitis as was demonstrated by histological quantification (total score 13.35 +/- 0.80 in treated rats versus 17.67 +/- 0.69 in the control group; P less than 0.01). The protective effect of phenylbutazone seems to be related to the specific anti-inflammatory properties of the drug and not to inhibition of prostaglandin synthesis.

[The induction of chondrogenesis after fracture repair]

Various experimental models have been used in young rabbits to determine the conditions necessary to induce chondrogenesis in the inner layer of periosteum after injury. Chondrogenesis will always occur in the presence of a haematoma, torn periosteum and bone, but if one of these factors in missing such a response may not necessarily occur.