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Biomedical subjects

P Buma

Publications and source records attributed to P Buma.

At least 55 records · Page 3Linked to original sources
PubMed2000

Incorporation of morsellized bone graft under controlled loading conditions. A new animal model in the goat.

The aim of this study was to develop a new animal model in which we could assess the in vivo effects of mechanical stimuli in the incorporation process of impacted morsellized bone grafts. The subcutaneous pressure implant SPI was developed for use in the goat. This device can generate controlled loading conditions onto a fixed amount of bone graft in the distal femur. Twenty goats were divided into three groups: non-loaded, 2 or 4 MPa loads (1 Hz, 1 h/day). The goats were sacrificed after 3, 6 or 12 weeks. The results were documented by clinical observations, quantitative bone density from QCT-scanning and histomorphometry. Nine post-mortem knee specimens were prepared in a similar manner to the experimental knees to determine the reproducibility and mechanical stability of the grafting method. Three goats were lost due to complications, the others functioned clinically well. Histology showed invasion of the bone graft by a front of vascular fibrous tissue after which osteoclasts resorbed the dead bone graft, followed by woven bone apposition on the graft remnants. At 12 weeks the loaded grafts had transformed into a vital trabecular structure. QCT bone density measurements revealed persistently high densities in the 12-weeks 4 MPa specimens, but reduced densities in the 2 MPa and non-loaded specimens. Morphometrically, the mineralising surface was larger in the 4 MPa group (P = 0.02) and the incorporation and remodelling processes had advanced more rapidly in the 2 MPa specimens (P = 0.04). Although the numbers investigated in this study in each group were low, statistical differences were found in the amount of graft left after incorporation and in the apposition rate of the new bone. In the future this model will be used to study the incorporation potential of different types of bone graft and bone graft substitutes.

Animals↗
PubMed2000

Acetabular reconstruction with impacted morcellized cancellous bone autograft and cemented primary total hip arthroplasty: a 10- to 17-year follow-up study.

During the period 1979 through 1986, 69 acetabular reconstructions in 63 patients were performed with the use of autologous morcellized bone-grafts because of acetabular bone stock loss. Nine cases (10 hips) were lost to follow-up. Eleven patients (12 hips) died <10 years after surgery; none had a revision. The results for the remaining 43 patients (47 hips) were reviewed at an average interval of 12.3 years (range, 10-17 years). No preoperative Harris hip score was available. The average Harris hip score at follow-up was 88 (range, 60-100). Radiographically, all grafts united. One hip developed a deep infection. Three other hips (6%) were revised because of aseptic loosening of the acetabular component. An additional 3 acetabular components were considered radiographic failures. Excluding the infected case, the overall survival rate of these acetabular reconstructions with a revision as endpoint was 94% at an average follow-up of 12.3 years. Reconstruction of acetabular bone stock loss with autologous morcellized bone-grafts is an attractive technique with a good potential for long-term success.

Acetabulum↗
PubMed2000

The role of femoral stem extension in total knee arthroplasty.

Although stemmed femoral components often are used in revision total knee arthroplasty, no quantitative comparison of the relative stability of a femoral component with and without a stem has been performed previously. A radiostereophotogrammetric analysis was performed to determine the influence of stem extension on mechanical stability in a laboratory experiment. In addition, the contribution of impacted morselized bone graft used for reconstruction of bone defects to stability was determined. Ten fresh frozen distal femoral specimens, of which the bone mineral density was measured, were prepared to fit a cemented femoral component with an uncemented stem. A cyclic axial load of 750 N was applied to the medial part of the femoral component. The loading test was repeated after creation of a standard, unicondylar, uncontained medial bone defect, after reconstruction of the defect with impacted morselized bone graft, after disconnecting the stem from the component, and after removal of the morselized bone graft. A significant difference was found in rotation and translation of the femoral component with the stem and after its functional removal. The femoral component rotated significantly into varus and internal rotation, and the tip of the stem translated significantly laterally after disconnection of the stem. A linear correlation between bone mineral density in the femoral neck and the radiostereophotogrammetric motion data was absent, but a bone mineral density threshold level of 0.55 g/cm2 was present, below which stability decreased considerably. Morselized bone graft provided only a minor contribution to stability compared with a stem.

Arthroplasty, Replacement, Knee↗
PubMed2000

Autologous morsellised bone grafting restores uncontained femoral bone defects in knee arthroplasty. An in vivo study in horses.

The properties of impacted morsellised bone graft (MBG) in revision total knee arthroplasty (TKA) were studied in 12 horses. The left hind metatarsophalangeal joint was replaced by a human TKA. The horses were then randomly divided into graft and control groups. In the graft group, a unicondylar, lateral uncontained defect was created in the third metatarsal bone and reconstructed using autologous MBG before cementing the TKA. In the control group, a cemented TKA was implanted without the bone resection and grafting procedure. After four to eight months, the animals were killed and a biomechanical loading test was performed with a cyclic load equivalent to the horse's body-weight to study mechanical stability. After removal of the prosthesis, the distal third metatarsal bone was studied radiologically, histologically and by quantitative and micro CT. Biomechanical testing showed that the differences in deformation between the graft and the control condyles were not significant for either elastic or time-dependent deformations. The differences in bone mineral density (BMD) between the graft and the control condyles were not significant. The BMD of the MBG was significantly lower than that in the other regions in the same limb. Micro CT showed a significant difference in the degree of anisotropy between the graft and host bone, even although the structure of the area of the MBG had trabecular orientation in the direction of the axial load. Histological analysis revealed that all the grafts were revascularised and completely incorporated into a new trabecular structure with few or no remnants of graft. Our study provides a basis for the clinical application of this technique with MBG in revision TKA.

Animals↗
PubMed2000

Scintigraphic evaluation of experimental chronic osteomyelitis.

UNLABELLED: Assessment of disease activity and disease extent in chronic osteomyelitis remains a difficult diagnostic problem. Radiography is not particularly sensitive. Scintigraphic techniques can be more helpful, but the routinely available agents lack specificity (99mTc-methylene diphosphonate [MDP], 67Ga-citrate) or are laborious to prepare (111In-leukocytes). We evaluated the performance of 2 new radiopharmaceuticals, 99mTc-polyethyleneglycol (PEG) liposomes and 99mTc-hydrazinonicotinamide (HYNIC)-immunoglobulin G (IgG), in an experimental model of chronic osteomyelitis. METHODS: Chronic osteomyelitis was induced in rabbits by inserting S. aureus into the right reamed and washed femoral canal. The canal was closed with cement. A sham operation was performed on the left femur. Routine radiographs were obtained immediately after surgery and before scintigraphy. Four weeks after surgery, each rabbit was injected with 37 MBq 99mTc-PEG liposomes, 99mTc-HYNIC-IgG, and 99mTc-MDP on 3 consecutive days and imaged up to 4 (MDP) or 22 (liposomes and IgG) h after injection. On day 4, rabbits received either 18 MBq 111In-granulocytes or 67Ga-citrate and were imaged up to 44 h after injection. Uptake in the infected femur was determined by drawing regions of interest. Ratios of infected-to-sham-operated femur were calculated. After the last image, the rabbits were killed, and the left and right femur were scored for microbiologic and histopathologic evidence of osteomyelitis. RESULTS: 99mTc-PEG liposomes and 99mTc-HYNIC-IgG correctly identified all 6 rabbits with osteomyelitis. 11In-granulocytes and 67Ga-citrate gave equivocal results in 1 infected rabbit. 99mTc-MDP missed 1 case of osteomyelitis. The uptake in the affected region did not differ significantly between the agents, although 99mTc-MDP tended to have higher values (MDP, 4.75 +/- 1.23 percentage injected dose per gram [%ID/g]; 67Ga, 2.05 +/- 0.54 %ID/g; granulocytes, 1.56 +/- 0.83 %ID/g; liposomes, 1.75 +/- 0.76 %ID/g, and IgG, 1.96 +/- 0.27 %ID/g). The ratios of infected-to-normal femur were also not significantly different for the respective radiopharmaceuticals. Radiography visualized only severe osteomyelitis. CONCLUSION: In this rabbit model, 99mTc-PEG liposomes and 99mTc-HYNIC-IgG performed at least as well as 111In-granulocytes and 67Ga-citrate in the localization of chronic osteomyelitis. The ease of preparation, the better image quality, and the lower radiation dose suggest that 99mTc-PEG liposomes and 99mTc-HYNIC-IgG might be suitable alternatives for 67Ga-citrate and 111In-granulocytes in the scintigraphic evaluation of osteomyelitis.

Animals↗
PubMed1999

Denaturation of type II collagen in articular cartilage in experimental murine arthritis. Evidence for collagen degradation in both reversible and irreversible cartilage damage.

Degradation of type II collagen is thought to be a key step in the destruction of articular cartilage in patients with rheumatoid arthritis or osteoarthritis. The aim of this study was to investigate whether type II collagen degradation is associated with cartilage destruction. Type II collagen degradation was studied in two murine arthritis models, zymosan-induced arthritis (ZIA), which develops reversible articular cartilage damage based on proteoglycan analysis, and antigen-induced arthritis (AIA), in which there is irreversible damage to the cartilage. Type II collagen degradation was assayed immunohistochemically using the COL2-3/4m antibody which recognizes denatured type II collagen, such as is produced by collagenase cleavage. In both models, degradation of type II collagen was observed in the non-calcified articular cartilage of arthritic but not of control knees. In the patella-femoral compartment, collagen denaturation started to increase on day 3 (ZIA) and day 7 (AIA) and remained high on day 14. In contrast, in the tibia-femoral compartment, type II collagen breakdown was not increased before 14 days in either model. By 28 days, collagen denaturation was strongly reduced in the patella-femoral compartment in the ZIA model, but persisted in the tibia-femoral compartment in both models. In conclusion, increased type II collagen degradation was found in articular cartilage of both ZIA and AIA animals. Since ZIA does not develop irreversible cartilage destruction, this indicates that cartilage may have the ability to withstand a limited degree of type II collagen degradation without developing irreversible damage.

Animals↗
PubMed1999

Cleavage of aggrecan at the Asn341-Phe342 site coincides with the initiation of collagen damage in murine antigen-induced arthritis: a pivotal role for stromelysin 1 in matrix metalloproteinase activity.

OBJECTIVE: The destruction of articular cartilage during arthritis is due to proteolytic cleavage of the extracellular matrix components. This study investigates the kinetic involvement of metalloproteinases (MMPs) in the degradation of the 2 major cartilage components, aggrecan and type II collagen, during murine antigen-induced arthritis (AIA). In addition, the role of stromelysin 1 (SLN-1) induction of MMP-induced neoepitopes was studied. METHODS: VDIPEN neoepitopes in aggrecan and collagenase-induced COL2-3/4C neoepitopes in type II collagen were identified by immunolocalization. Stromelysin 1-deficient knockout (SLN1-KO) mice were used to study SLN-1 involvement. RESULTS: In AIA, the VDIPEN epitopes in aggrecan appeared after initial proteoglycan (PG) depletion. The collagenase-induced type II collagen neoepitopes colocalized with VDIPEN epitopes. Remarkably, cartilage from arthritic SLN1-KO mice showed neither the induction of VDIPEN nor collagen cleavage-site neoepitopes during AIA, suggesting that stromelysin is a pivotal mediator in this process. PG depletion, as measured by the loss of Safranin O staining, was similar in SLN1-KO mice and wild-type strains. Furthermore, in vitro induction of VDIPEN epitopes in aggrecan and COL2-3/4C epitopes in type II collagen, on exposure of cartilage to interleukin-1, could not be accomplished in SLN1-KO mice, whereas intense staining was achieved for both epitopes in cartilage of wild-type strains. CONCLUSION: This study emphasizes that SLN-1 is essential in the induction of MMP-specific aggrecan and collagen cleavage sites during AIA. It suggests that SLN-1 is not a dominant enzyme in PG breakdown, but that it activates procollagenases and is crucial in the initiation of collagen damage.

Aggrecans↗
PubMed1999

Type II collagen degradation in spontaneous osteoarthritis in C57Bl/6 and BALB/c mice.

OBJECTIVE: Degradation of type II collagen during osteoarthritis (OA) is thought to be the key process leading to cartilage destruction. In this study, we investigated whether OA is characterized by either a generalized breakdown of the collagenous network or a localized process. Furthermore, we determined if collagen degradation was linked to cell death. METHODS: Two mouse strains that develop spontaneous OA, C57Bl/6 and BALB/c mice, were examined. Type II collagen degradation in type II collagen-induced arthritis was also examined for comparison. Immunolocalization with the COL2-3/4m and COL2-3/4C antibodies was used to demonstrate denatured type II collagen and the collagenase cleavage site in type II collagen, respectively. RESULTS: Both the C57Bl/6 and the BALB/c mice developed OA changes, although clear compartmental differences existed between the two strains. In both strains, type II collagen degradation was clearly present at sites of degeneration, but was absent from intact articular cartilage. Collagen degradation was absent from areas with cell death. CONCLUSION: These results indicate that type II collagen degradation in spontaneous murine OA is associated with degeneration and is a localized, instead of a generalized, process.

Animals↗
PubMed1999

Cryosurgery in long bones; an experimental study of necrosis and revitalization in rabbits.

Cryosurgery is an established adjuvant treatment of bone tumors which reduces the local recurrence rate. In this study, cryosurgical experiments were carried out in rabbits to study the temperature field, the extent of necrosis, and the revitalization process in order to optimize treatment. Intramedullary freezing of long bones with a closed liquid nitrogen cryoprobe and three consecutive sessions induces osteonecrosis down to the -10 degrees C isotherm without compromising the soft tissues. The application of a tourniquet does not influence the thermodynamics. The revitalization process is distinguished into an osteogenic and a remodelling phase. In rabbits, there is an obvious periosteal osteogenesis starting from 1 week after operation and overlapping the remodelling phase, which starts between 3 and 5 weeks after operation. Two out of eight rabbits sustained a pathologic fracture within 3 weeks of cryosurgery. No pathologic fractures were encountered during the remodelling phase, probably because of the profuse periosteal bone apposition that added mechanical strength. In clinical practice, no profound periosteal bone apposition and a high risk for pathologic fractures during the remodelling phase were noted. Future research should focus on bone strength during the remodelling phase of cryosurgically treated long bones, to decide on the role of preventive osteosynthesis or postoperative restrictions. This animal model is not advised for these biomechanical experiments because of its profuse periosteal bone apposition.

Animals↗
PubMed1999

Resurfacing potential of heterologous chondrocytes suspended in fibrin glue in large full-thickness defects of femoral articular cartilage: an experimental study in the goat.

A large full-thickness articular-cartilage defect was created in the medial femoral condyle of 32 adult goats. The defects were xenografted with isolated rabbit chondrocytes suspended in fibrin glue. Sham operated goats, where only a standardized defect was created, were used as controls. Results of cartilage repair were assessed after 3, 8, 13, 26 and 52 weeks. The repair tissue was evaluated macroscopically, histologically and biochemically. Results indicated that xenografted rabbit chondrocytes survived the transplantation and maintained their potential to produce matrix in fibrin glue, particularly if they were located in a non-weight-bearing area. In terms of an immunological reaction to xenografted chondrocytes, only mild signs of synovitis were observed in both groups and rejection of transplanted cells did not occur. From 3 weeks gradually progressive resolvement of the fibrin glue was observed with subsequent replacement by fibrous tissue. Initially xenografted defects histologically showed better tendency for cartilage regeneration, however, 52 weeks after surgery no significant differences could be detected in the repair tissue of both groups macroscopically, histologically and on biochemical scoring. The amount of collagen type II in the newly synthesized matrix was 75% 1 year after surgery. This study shows that isolated heterologous chondrocytes can be used for transplantation in articular cartilage defects, however, fibrin glue does not offer enough biomechanical support to the cells to maintain its function as a three-dimensional scaffold.

Animals↗
PubMed1999

Morsellized bone grafting compensates for femoral bone loss in revision total knee arthroplasty. An experimental study.

This study was undertaken to examine the contribution of uncontained morsellized bone graft to the structural properties of a femoral reconstruction in total knee arthroplasty and to serve as a basis for an in vivo animal study. Ten human distal femora with a standard unicondylar uncontained medial bone defect were prepared to fit a femoral component of a cruciate sacrificing TKA. A cyclic axial load of 750 N was applied to the medial part of the femoral component in the presence of impacted morsellized bone graft. After removal of the bone graft, the cyclic loading was repeated for the unsupported situation. None of the grafts collapsed and all cement mantles stayed intact during the experiments. Elastic deformation during cyclic loading was significantly less when graft was added while time-dependent deformation was not affected. We conclude that impacted morsellized bone graft, used for reconstruction of uncontained femoral bone loss in revision knee arthroplasty, may improve the structural resistance against loading. Further animal experimentation for in vivo application is warranted.

Animals↗
PubMed1999

Mechanical characteristics of impacted morsellised bone grafts used in revision of total hip arthroplasty.

The use of impacted, morsellised bone grafts has become popular in revision total hip arthroplasty (THA). The initial stability of the reconstruction and the effectiveness of any subsequent process of revitalisation and incorporation will depend on the mechanical integrity of the graft. Our aim in this study was to document the time-dependent mechanical properties of the morsellised graft. This information is useful in clinical application of the graft, in studies of migration of the implant and in the design of the joint. We used 16 specimens of impacted, morsellised cancellous bone from the sternum of goats to assess the mechanical properties by confined compression creep tests. Consideration of the graft material as a porous, permeable solid, filled with fluid, allowed determination of the compressive modulus of the matrix, and its permeability to fluid flow. In all specimens the compression tests showed large, irreversible deformations, caused by flow-independent creep behaviour as a result of rolling and sliding of the bone chips. The mean permeability was 8.82 *10(-12) m4/Ns (SD 43%), and the compressive modulus was 38.7 MPa (SD 34%). No correlation was found between the apparent density and the permeability or between the apparent density and the compressive modulus. The irreversible deformations in the graft could be captured by a creep law, for which the parameters were quantified. We conclude that in clinical use the graft is bound to be subject to permanent deformation after operation. The permeability of the material is relatively high compared with, for example, human cartilage. The confined compression modulus is relatively low compared with cancellous bone of the same apparent density. Designs of prostheses used in revision surgery must accommodate the viscoelastic and permanent deformations in the graft without causing loosening at the interface.

Animals↗
PubMed1999

Femoral bone loss in total knee arthroplasty. A review.

Femoral bone loss in total knee arthroplasty (TKA) is a common feature and is mainly attributed to three etiological factors. Stress shielding causes an "osteopenia" type of bone loss behind the anterior flange and adjacent to the distal aspects of the femoral component. Using dual-energy x-ray absorptiometry, decrease in bone mineral density up to 44% has been measured in these areas. Secondly, polyethylene, cement and metal particles are released by implant wear and may cause the less common "osteolysis" type of bone loss located directly at the anterior and posterior implant-cement-bone interfaces. This type of bone loss occurs mainly in young, male, overweight patients with osteoarthritis. Finally, implant loosening leads to bone loss at the bone cement-implant interface and results in "hollowing out" of the distal femur in a stemmed TKA. Femoral bone loss may be reduced by diminishing the stress-shielding effect, by improving the quality of the polyethylene insert, and by decreasing the rate of implant loosening still further. In revision TKA, femoral bone loss is often underestimated in the preoperative radiographs. Classification of bone loss should be made during surgery, and should be based upon the size of the defect generated and the grade of containment. The choice among cement filling, metal augmentation, custom-made TKA, solid bone grafts, and morsellized bone grafts in reconstruction of bone defects will depend upon the type of bone loss, the bone quality, the surgeon's preference and philosophy, and the availability of grafts and implants.

Absorptiometry, Photon↗
PubMed1999

Femoral bone grafting in primary and revision total knee arthroplasty.

The purpose of this study was to evaluate the clinical and radiographic results of TKA's with morsellized and solid femoral bone grafting. From April 1989 to February 1996, 6 primary and 18 revision TKA's with femoral bone grafting were performed in 22 patients with an average age of 62 years. Eleven knees were affected by rheumatoid arthritis, 10 by osteoarthritis, 2 by osteonecrosis and one by hemophiliac arthropathy. The femoral bone defects were large in 12, medium in 9, small in 3, contained in 10 and uncontained in 14 cases. Reconstruction was done with impacted morsellized fresh frozen trabecular bone grafts in 13 knees, with solid bone grafts in 7 knees and with combined grafts in 4 knees. Twenty-one cases were clinically evaluated at an average of 38 months (range: 9-89 months). The average Knee Society knee score increased by 39 points to 85 points at follow-up. The average functional score increased by 22 points to 48 points. Two cases with solid femoral bone grafts failed due to aseptic loosening. There were no infections. Radiographic follow-up revealed osteopenia around the femoral component in 10 knees. Two knees showed circumferential radiolucency around the femoral stem, and 5 knees had minor radiolucency at the anterior part of the femoral component. Radiographic incorporation was present in 5 of the 6 cases that could be evaluated. Histologic analysis of two biopsies revealed incorporation of the morsellized bone graft. The authors advocate impacted morsellized bone grafting for contained and small-to-medium uncontained femoral bone defects in combination with cemented TKA.

Adult↗
PubMed1999

Role of growth factors in the incorporation of unloaded bone allografts in the goat.

Revision of a failed total joint replacement often demands bone grafting methods to restore deficient bone stock. However, impaired allograft incorporation can be the result of inadequate host or graft properties. The stimulation of bone healing with growth factors could provide a new approach to deal with this problem. The repeated sampling bone chamber was used in the goat to investigate the properties of bone allografts enriched with transforming growth factor-beta, recombinant human bone morphogenetic protein-2, and basic fibroblastic growth factor under unfavorable vascular and nonloaded conditions. Ten goats each had three bone chambers implanted in the medial proximal tibia. Different carrier allograft bone preparations were used for each growth factor based on convention and previously reported results. The period between implantation and chamber harvest was 8 weeks. The concentrations of the growth factors used was 0, 1, or 10 micrograms of transforming growth factor-beta 2, 0, 1, or 5 micrograms of bone morphogenetic protein-2, and 0, 40, 200 ng of basic fibroblastic growth factor. The specimens were analyzed histomorphometrically for the amount of soft tissue ingrowth, bone ingrowth, and the number of osteoclasts. In all specimens, a resorption front grew into the graft followed by fibrovascular tissue and, in some instances, bone. In the 5 micrograms of bone morphogenetic protein-2 specimens, larger amounts of soft tissue and woven bone were present, whereas in the specimens that received 10 micrograms of transforming growth factor-beta 2, there was a decrease in the amount of tissue and bone ingrowth. Two hundred nanograms of basic fibroblastic growth factor had a negative effect on soft tissue formation but increased the amount of vascular elements containing erythrocytes. The number of osteoclasts was higher in the 5-microgram bone recombinant human morphogenetic protein-2 specimens. In the clinical arena with absence of good perigraft vascularization and loading, bone morphogenetic protein-2 may have a strong stimulatory effect on bone graft incorporation.

Animals↗
PubMed1998

Chondrocyte-seeded hydroxyapatite for repair of large articular cartilage defects. A pilot study in the goat.

The aim of this study was to evaluate the potential for restoration of a large cartilage defect in the goat knee with hydroxyapatite (HA) loaded with chondrocytes. Isolated chondrocytes were suspended in fibrin glue, seeded on top of the HA, and then the composite graft was implanted in the defect. After transplantation, cell behaviour, newly synthesised matrix and the HA-glue interface were assessed histologically after 2, 4, 12, 26 and 52 weeks. Special attention was paid to the incorporation process of HA in the subchondral bone and interactions between this biomaterial and the fibrin-glue-chondrocyte suspension. Chondrocytes in the glue proved to survive the transplantation procedure and produced new metachromatically stained matrix two weeks after implantation. The glue-cell suspension had penetrated the superficial porous structure of the HA. Four weeks after surgery, islands of hyaline-like cartilage were observed at the HA-glue interface. A layer of fibrous tissue was formed surrounding the HA graft, resulting in a relatively instable fixation of the HA in the defect. This instability of the graft in the defect, possibly together with early weight bearing, resulted in a gradual loss of the newly formed hyaline cartilage-like repair tissue. Progressive resorption of the HA occurred without any sign of active bone remodelling from the host site. One year after surgery part of the defect which extended down to the cancellous bone had been predominantly restored with newly formed lamellar bone. Only small HA remnants were still present at the bottom of the original defect. Resurfacing of the joint had occurred with fibrocartilaginous repair tissue. The absence of adequate fixation capacity of the HA near the joint space resulted in a relative instability of the graft with progressive resorption. Therefore, HA is not a suitable biomaterial to facilitate the repair of large articular cartilage defects.

Animals↗