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Biomedical subjects

K Kawanabe

Publications and source records attributed to K Kawanabe.

At least 19 recordsLinked to original sources
PubMed2006

The biocompatibility and osteoconductivity of a cement containing beta-TCP for use in vertebroplasty.

A new composite bone cement designated "G2B1" was developed for percutaneous transpedicular vertebroplasty. G2B1 contains beta tricalcium phosphate particles and methylmethacrylate-methylacrylate copolymer as the powder components, and methylmethacrylate, urethane dimethacrylate, and tetrahydrofurfuryl methacrylate as the liquid components. Biocompatibility and osteoconductivity were evaluated using scanning electron microscopy, contact microradiography, and Giemsa surface staining 4, 8, 12, 26, and 52 weeks after implantation into rat tibiae. To evaluate osteoconductivity, affinity indices (%) were calculated. Scanning electron microscopy and contact microradiography revealed that bone contact with G2B1 was attained within 4 weeks (affinity index: 50.2 +/- 11.8 at 4 weeks) and at most of the margin within 26 weeks (affinity index: 87.4 +/- 7.2 at 26 weeks). Specifically, G2B1 contacted bone via a wide calcium-phosphate-rich layer, and its degradation started within 8 weeks, mainly in the marginal area. Giemsa surface staining showed that there was almost no inflammatory reaction around the G2B1. These results indicate that G2B1 is a biocompatible and osteoconductive bone cement.

Animals↗
PubMed2005

Novel intramedullary plug with sliding mechanism used in revision total knee arthroplasty.

A novel intramedullary plug with sliding mechanism has been developed and evaluated clinically in the settings of revision total knee arthroplasty (TKA). The new plug consists of a pair of specially designed components. Each component is shaped like an obliquely cut cylinder. Postoperative plain radiographs of 8 arthroplasties that include 7 stemmed femoral components and 6 stemmed tibial components (total 13 regions) were examined. No radiolucent line between the cement and the cortical bone was observed. Plugging was complete in 11 regions. No migration of the plug was observed. Slight leak of the cement was observed in 2 of 7 femoral components, but not found in tibial components. Our study demonstrated the efficacy of the plug in occluding the femoral and tibial canal completely in 11 out of 13 regions in revision TKAs.

Aged↗
PubMed2005

Discerning alumina ball wear from confounding metal transfer artifact.

On dismounting a ceramic femoral ball from its metal trunnion, there is usually a range of gray metallic bands transferred to the trunnion bore inside the ball. This creates an artifact that may compromise detection by weight of the exceedingly low wear rates of ceramic balls. The objective of this study was to compare the weight trending of the metal trunnions and their ceramic balls during conditioning studies. Our hypothesis was that a pretest conditioning protocol would eliminate or greatly reduce the metal transfer artifact. The balls and tapers were placed on a hip simulator under 300-600 load cycles but with no articulation. The balls were then dismounted from the trunnions, and both were cleaned and weighed. This was repeated 6-23 times. We developed a novel hydraulic method for dismounting balls from trunnions that proved to be safe and efficient. There was significant weight loss in the trunnions after the ball removal, but there was no corresponding weight gain in the alumina balls. The weight effect of the metal transfer appeared to have been removed from the balls with our standard cleaning procedures. Therefore, wear rates for alumina balls may be gravimetrically determined without compensating for the metal transfer from trunnion to ball.

Aluminum Oxide↗
PubMed2003

Effect of alumina femoral heads on polyethylene wear in cemented total hip arthroplasty. Old versus current alumina.

We examined the behaviour of alumina ceramic heads in 156 cemented total hip arthroplasties, at a minimum follow-up of eight years. They were divided into three groups according to the size of the femoral head; 22, 26, and 28 mm. We measured polyethylene wear radiologically using a computer-aided technique. The linear wear rate of polyethylene sockets for the 28 mm heads was high (0.156 mm/year), whereas those for the 22 and 26 mm heads were relatively low (0.090 and 0.098 mm/year, respectively). Moreover, the surface roughness data of retrieved femoral heads clearly showed maintenance of an excellent surface finish of the current alumina. We conclude that the alumina ceramic femoral heads currently used are associated with a reduced rate of polyethylene wear.

Adult↗
PubMed2003

Candida septic arthritis of the hip in a young patient without predisposing factors.

We present a case of septic arthritis of the hip caused by Candida albicans in a 24-year-old woman. This is the first report of a Candida infection of the hip in a patient without any predisposing factors. She underwent a two-stage total hip arthroplasty three years after the onset of the infection. An elevated plasma level of beta-D-glucan suggested Candida as the infecting organism and the diagnosis might have been made earlier if this test had been undertaken at presentation.

Adult↗
PubMed2002

The modified Spitzy shelf operation for patients with dysplasia of the hip. A 24-year follow-up study.

We evaluated the long-term results of a modified Spitzy shelf operation for secondary osteoarthritis in 119 hips with a mean follow-up of 23.8 years. The mean age of the patients at the time of surgery was 25 years. Preoperative osteoarthritic change, the age at operation and shelf height were important factors in determining the outcome. Of the 61 hips in the pre-stage (three) and the initial stage (58) of osteoarthritis, 53 (87%) had good results, compared with only 30 (51%) of 58 hips with advanced osteoarthritis. Of the latter, 72% of those aged less than 25 years had good results compared with only 40% of patients aged over 25 years. The shelf height in the group with good results was significantly lower than in those with poor results. This operation is a safe procedure and indicated for acetabular dysplasia or subluxation of the hip with early osteoarthritic change in patients aged less than 25 years.

Acetabulum↗
PubMed2001

Bone bonding in sintered hydroxyapatite combined with a new synthesized agent, TAK-778.

We studied the stimulatory effects of TAK-778, a new synthetic 3-benzothiepin derivative that promotes osteoblast differentiation, in bone bonding to sintered hydroxyapatite implants in rabbit tibiae. Smooth-surfaced rectangular plates (15 x 10 x 2 mm) made of sintered hydroxyapatite were implanted into the proximal metaphyses of bilateral rabbit tibiae, with TAK-778-containing sustained-release microcapsules packed into the medullary cavity in one limb and untreated microcapsules packed in the contralateral limb to serve as a paired control. At 4, 8, and 16 weeks after implantation, bone bonding at the bone-implant interfaces was evaluated by a detaching test and undecalcified histological examination. The tensile failure load increased from 4 to 16 weeks for both groups; however, the tensile failure load of the TAK-778-treated group was significantly greater than that of the control group at each interval after implantation. Histologically, the TAK-778-treated specimens showed greater active new bone formation mainly in the medullary cavity and more extensive bonding between the implant and bone than the untreated specimens. The results of this study suggest that adding osteoinductive TAK-778 to hydroxyapatite implants may significantly accelerate bone apposition to the implants and improve the bonding process at the interface. This would help to establish an earlier and stronger bonding of orthopedic ceramic implants between the surrounding bone tissue.

Absorbable Implants↗
PubMed2001

Effects of A-P translation and rotation on the wear of UHMWPE in a total knee joint simulator.

We developed a three-channel total knee joint simulator and studied the effect of tibial anterior-posterior translation and internal/external rotation on the wear of polyethylene tibial inserts in total knee replacements (Anatomic Graduated Component knees). The wear rate was the lowest in experiment (Exp.) 1, without translation and rotation [1.74 mg/million (mg/Mc) cycles]. In Exp. 2, with +/-5 degrees tibial rotation added, the wear rate increased to 10.6 mg/Mc. In Exp. 3, with rotation and -12 mm tibial translation added, the wear rate was 15.1 mg/Mc, whereas in Exp. 4, with rotation and +12 mm tibial translation, the wear rate was 18.7 mg/Mc. Internal/external rotation and anterior-posterior translation added a 6- to 11-fold increase in the wear rates of tibial knee inserts. The shapes of the tibial wear tracks were rectangular and the area of the track increased when rotation and translation were added.

Biomechanical Phenomena↗
PubMed2000

Alumina powder/Bis-GMA composite: effect of filler content on mechanical properties and osteoconductivity.

Three composites consisting of alumina powder dispersed in a bisphenol-a-glycidyl methacrylate (Bis-GMA) matrix were prepared and evaluated to assess the effect of alumina powder content on the mechanical properties and osteoconductivity of the composite. The alumina powder composites (APC) consisted of alumina powder (AL-P) as the inorganic filler dispersed in a Bis-GMA matrix that was solidified by a radical polymerization process. Prior to polymerization the AL-P was mixed with the monomers in proportions of 50%, 70%, and 80% by weight (APC50, APC70, and APC80). A fused silica-glass-filled composite containing 70% glass by weight (SGC70) was used as a control. The compressive and bending strengths, the elastic modulus in bending, and the bending strain of the composites increased as the AL-P content increased. We also evaluated the composites in vivo by implanting them into the medullary canals of rat tibiae. To compare the osteoconductivity of the composites, an affinity index was calculated for each composite; the affinity index equals the length of a bone in direct apposition to the composite and is expressed as a percentage of the total length of the composite surface. Microradiographic examination for periods of up to 26 weeks after implantation revealed that APC50, APC70, and APC80 all exhibited excellent osteoconductivity and made direct contact with the bone with no interposed soft tissues. However, the higher the AL-P content of the composite, the higher the osteoconductivity, especially at 4 weeks after the operation. Moreover, the amount of bone directly apposed to the composite surface increased with time. In contrast, little bone formation was seen on the surface of SGC70, even after 26 weeks. Observation by scanning electron microscope-energy dispersive X-ray microanalysis demonstrated that bone made direct contact with the APC surface through a layer containing calcium, phosphorus, and alumina powder. These results suggest that APC shows promise as a basis for developing mechanically strong and highly osteoconductive composites.

Aluminum Oxide↗
PubMed2000

Cemented total hip arthroplasty with acetabular bone graft for developmental dysplasia. Long-term results and survivorship analysis.

Although the technique of autogenous acetabular bone grafting has been widely used to augment containment of the acetabulum in total hip arthroplasty (THA) for developmental dysplasia, the role of this technique in improving long-term results remains controversial. We present the long-term results of cemented THA with acetabular bone grafting in 112 patients (133 hips) in order to clarify the factors which affect the outcome. The mean follow-up was for 12.3 years (8 to 24). Kaplan-Meier survivorship analysis predicted a rate of survival of the acetabular component at 15 years of 96% (95% confidence interval (CI) 92 to 99) with revision for aseptic loosening as the endpoint, and of 75% (95% CI 65 to 85) when radiological loosening was used. Parametric survivorship analysis using the Cox proportional-hazards model indicated that trochanteric nonunion, lateral placement of the socket, and delayed trabecular reorientation of the bone graft were risk factors for loosening of the acetabular component. Our findings have shown that autologous acetabular bone grafting is of value for long-term success provided that the risk factors are reduced.

Acetabulum↗
PubMed1999

Repair of segmental bone defects using bioactive bone cement: comparison with PMMA bone cement.

We developed a bioactive bone cement (BABC) that consists of apatite and wollastonite containing glass ceramic (AW-GC) powder and bisphenol-A-glycidyl dimethacrylate (Bis-GMA) based resin. In the present study, the effectiveness of the BABC for repair of segmental bone defects under load-bearing conditions was examined using a rabbit tibia model. Polymethylmethacrylate (PMMA) bone cement was used as a control. A 15-mm length of bone was resected from the middle of the shaft of the tibia, and the tibia was fixed by two Kirschner wires. The defects were replaced by cement. Each cement was used in 12 rabbits; six rabbits were sacrificed at 12 and 25 weeks after surgery, and the tibia containing the bone cement was excised and tension tested. At both the intervals studied, the failure loads of the BABC were significantly higher than those of the PMMA cement. The BABC was in direct contact with bone, whereas soft tissue was observed between the cement and bone in all PMMA cement specimens. Results indicated that the BABC was useful as a bone substitute under load-bearing conditions.

Animals↗
PubMed1999

Pressurization of bioactive bone cement in vitro.

We have developed a bioactive bone cement consisting of MgO-CaO-SiO2-P2O5-CaF2 glass-ceramic powder (AW glass-ceramic powder), silica glass powder as an inorganic filler, and bisphenol-a-glycidyl methacrylate (bis-GMA) based resin as an organic matrix. The efficacy of this bioactive bone cement was investigated by evaluating its pressurization in a 5-mm hole and small pores using a simulated acetabular cavity. Two types of acetabular components were used (flanged and unflanged sockets) and a commercially available polymethylmethacrylate (PMMA) bone cement (CMW 1 Radiopaque Bone Cement) was selected as a comparative control. Bioactive bone cement exerted greater intrusion volume in 5-mm holes than PMMA bone cement in both the flanged and unflanged sockets 10 minutes after pressurization (p < 0.05). In the small pores the bioactive and PMMA bone cements exerted almost identical intrusion volumes in flanged and unflanged sockets 10 min after pressurization. The intrusion volume in the flanged socket 10 minutes after pressurization was greater than that in the unflanged socket in all groups (p < 0.05). These results show that bioactive bone cement intrudes deeper into anchor holes than PMMA bone cement.

Biocompatible Materials↗
PubMed1999

Quantitative comparison of osteoconduction of porous, dense A-W glass-ceramic and hydroxyapatite granules (effects of granule and pore sizes).

The osteoconductive potentials of dense, small porous and large porous apatite- and wollastonite-containing glass-ceramic (A-W GC) granules of various sizes implanted in rat tibiae were evaluated quantitatively, by determining their affinity indices. The average affinity indices of all types of A-W GC were high. The dense A-W GC granules had the highest values (97.0+/-5.5%), followed by the large porous (87.1+/-8.4%) and then the small porous granules (79.0+/-8.4%). There were no significant differences among the osteoconductive potentials of the different sizes of each form of A-W GC granule. The osteoconductive potentials of four types of commercially available porous hydroxyapatite (HA) granules were compared with those of the small porous A-W GC granules, using the affinity index and the proportion of newly formed bone relative to that of the granules in the bone defect. The values of the former parameter for three types of HA and those of the latter for four were significantly inferior to those of A-W GC. The difference between the osteoconductive potentials of A-W GC and HA was considered to be related to the rate of surface apatite layer formation.

Animals↗
PubMed1998

Effect of polymerization reaction inhibitor on mechanical properties and surface reactivity of bioactive bone cement.

We introduced an inhibitor to the polymerization reaction of bioactive bone cement (AWC) consisting of MgO-CaO-SiO2-P2O5-CaF2 apatite and wollastonite containing glass-ceramic powder and bisphenol-alpha-glycidyl methacrylate based resin, together with an increased amount of accelerator but without any prolongation of its setting time in order to improve the degree of polymerization and decrease the amount of incompletely polymerized monomers on the cement surface. A comparison was made between the AWC containing the inhibitor [AWC(I+)] and the AWC without it [AWC(I-)] with regard to setting parameters, mechanical properties, and surface reactivity in vitro and in vivo. The proportion of glass-ceramic powder added to the AWC was 70% (w/w). The total amount of heat generation and the peak temperature of the AWC(I+) during polymerization were slightly greater than those of the AWC(I-). The mechanical strength of AWC(I+) was higher than that of the AWC(I-) under wet conditions. In simulated body fluid, the width of the Ca-P rich layer on the surface of the AWC(I+) was less than that on the AWC(I-) after 28 days of immersion, although the rate of apatite formation on the top surface of the AWC(I+) was almost identical to that on the AWC(I-) surface. Histological examination using rat tibiae up to 26 weeks revealed that the bioactivity of the AWC(I+) was equivalent to that of the AWC(I-). Scanning electron microscopy and energy-dispersive X-ray microanalysis demonstrated that the Ca-P rich layer in the AWC(I+) was significantly narrower than that in the AWC(I-) at the same time points. These results indicate that introduction of the inhibitor improved the mechanical properties of the AWC and made the Ca-P rich layer narrower, but it had no adverse effect on bioactivity.

Animals↗
PubMed1998

Development of bioactive bone cement and its clinical applications.

This paper is a summary of already published papers on the bioactive bone cement (BA cement) which consists of CaO-SiO2-P2O5-MgO-CaF2 (AW glass-ceramic) powder and bisphenol-a-glycidyl methacrylate (Bis-GMA) resin. Two types of BA cement, dough and injection type, were prepared by changing their chemical compositions slightly. They harden in a few minutes exhibiting much lower curing temperature than PMMA cement. They have significantly higher compressive, bending, and tensile strengths than PMMA cement and have a character of bonding directly with bone in 4-8 weeks in vivo. Intercalary prosthetic replacement of the femur and total prosthetic replacement of the hip were performed in dogs using either PMMA cement or BA cement. Mechanical tests demonstrated that fixation strengths of these prostheses with BA cement increased with time and were significantly greater than those with PMMA cement tested at any time. Results of histological examinations showed direct bonding between BA cement and bone, and that the bone trabeculae around BA cement mantle grew with time, while with PMMA cement an intervening soft tissue layer was always observed at the cement-bone interface. BA cement was used in a few aged patients to install a hip prosthesis either in cases of revision or femoral neck fracture. The longest follow-up period of the patient is 4 yrs. The patients have been doing well with no adverse effect of the cement to date.

Animals↗
PubMed1998

Treatment of osteomyelitis with antibiotic-soaked porous glass ceramic.

We have developed a new drug delivery system using porous apatite-wollastonite glass ceramic (A-W GC) to treat osteomyelitis. A-W GC (porosity, 70% and 20% to 30%), or porous hydroxyapatite (HA) blocks (porosity 35% to 48%) used as controls, were soaked in mixtures of two antibiotics, isepamicin sulphate (ISP) and cefmetazole (CMZ) under high vacuum. We evaluated the release concentrations of the antibiotics from the blocks. The bactericidal concentration of ISP from A-W GC was maintained for more than 42 days, but that from HA decreased to below the detection limit after 28 days. The concentrations of CMZ from both materials were lower than those of ISP. An in vivo study using rabbit femora showed that an osseous concentration of ISP was maintained at eight weeks after implantation. Osteoconduction of the A-W GC block was good. Four patients with infected hip arthroplasties and one with osteomyelitis of the tibia have been treated with the new delivery system with excellent results.

Adult↗