Biomedical subjects

Nozomu Inoue

Publications and source records attributed to Nozomu Inoue.

25 records · Page 2Linked to original sources

PubMed2002

Kinematic simulation of fracture reduction and bone deformity correction under unilateral external fixation.

Combined kinematic analysis and graphic models of two unilateral external fixators are presented to simulate and visualize the correction of bone fracture deformities through systematic adjustments of the fixator joints. The models were developed as rigid linkage systems, and the analysis utilized the 4x4 transformation matrices and the kinematic chain theory to obtain the necessary rotations and translations at each joint of the fixator to correct bone deformities at the fracture site. Three-dimensional malalignments with fracture gaps were simulated to correct the deformities. Due to the redundant pair variables in the fixator joints and other problems in obtaining unique solutions, an optimization technique was used to solve the governing linkage loop equations. For each adjustment solution, the bone correction paths were infinite but a unique and optimal reduction path was obtained by applying corrections to all joints simultaneously and in small increments. When the deformity exceeded a certain range, no admissible solution could be obtained, partially due to the limitation of the unilateral fixator configuration and partially due to the restricted joint rotation and translation in the fixator design. The present models and analysis technique can be used to investigate a fixator's adjustability to correct a 3-D bone deformity at a fracture or lengthening site facilitating patient care planning and medical personnel training.

Biomechanical Phenomena↗

PubMed2002

The effect of low intensity pulsed ultrasound applied to rabbit tibiae during the consolidation phase of distraction osteogenesis.

The purpose of this study was to determine if low intensity pulsed ultrasound (LIPU) accelerated the maturation of regenerate bone when applied after distraction in a rabbit model. A mid-tibial osteotomy was performed in 26 New Zealand white rabbits and an external fixator applied anteromedially. After a seven day latency period, the tibiae were distracted 0.5 mm every 12 h for 10 days. Thirteen of the rabbits received LIPU for 20 min/day (treatment group) and 13 received sham LIPU (control group) from day 17 until sacrifice on day 37. Radiographs were taken weekly after distraction and the total and mineralized areas of the callus were measured. After sacrifice, dual-energy X-ray absorptiometry, torsional testing to failure, and histomorphometry were performed. Ultrasound-treated tibiae were a mean of 68.8 +/- 3.8% as stiff as and 68.2 +/- 6.0% as strong as the contralateral tibiae. Control tibiae were 78.7 +/- 7.0%, as stiff as and 70.2 +/- 7.9% as strong as the contralateral tibiae. The differences in stiffness and strength were not significant (p = 0.39 and 0.81, respectively) with the number of the animals tested in the study. The treatment group was 91.6% as dense as the contralateral side and the control group was 88.5% as dense as the contralateral side (p = 0.84). Radiographs revealed a significantly larger callus in the LIPU-treated tibiae at 1, 2 and 3 weeks after distraction compared to control tibiae (p < 0.01, 0.008 and 0.05, respectively). Histomorphometry revealed significantly less fibrous tissue in the LIPU-treated tibiae (p < 0.05) and a strong trend towards more bone in the LIPU-treated tibiae compared to controls (p = 0.06). LIPU was found to increase the size of the distraction callus and it might alter the composition of regenerate bone but it did not have a positive effect on the mechanical properties or density of regenerate bone when applied during the consolidation phase of distraction osteogenesis.

Animals↗

PubMed2002

Effect of pulsed electromagnetic fields (PEMF) on late-phase osteotomy gap healing in a canine tibial model.

The effects of a pulsed electromagnetic field (PEMF) on late bone healing phases using an osteotomy gap model in the canine mid-tibia were investigated. A transverse mid-diaphyseal tibial osteotomy with a 2-mm gap was performed unilaterally in 12 adult mixed-breed dogs and stabilized with external fixation. Animals in the variable group (n = 6) were treated with PEMF for 1 h daily starting 4 weeks after surgery for a total of 8 weeks, whereas no stimulation signal was generated in the control group (n = 6). Functional load-bearing and radiographic assessments were conducted time-sequentially until euthanasia 12 weeks after surgery. Torsional tests and an analysis of undecalcified histology were performed on the retrieved mid-tibial diaphysis containing the osteotomy site. In the PEMF group, load-bearing of the operated limb recovered earlier when compared to the control group (p < 0.05). Load-bearing in the PEMF group at 8 weeks was greater than in the control group (p < 0.02). The periosteal callus area increased following surgery at 6 weeks (p < 0.05) and thereafter (p < 0.01) in the PEMF group, while a significant increase was observed at 8 and 10 weeks after surgery (p < 0.05) in the control group. Both the normalized maximum torque and torsional stiffness of the PEMF group were significantly greater than those of the control group (p < 0.04 and p < 0.007, respectively). Histomorphometric analyses revealed greater new-bone formation (p < 0.05) in the osteotomy gap tissue and increased mineral apposition rate (p < 0.04) and decreased porosity in the cortex adjacent to the osteotomy line (p < 0.02) in the PEMF group. PEMF stimulation of 1 h per day for 8 weeks provided faster recovery of load-bearing, a significant increase in new bone formation, and a higher mechanical strength of the healing mid-tibial osteotomy. This study revealed enhancing effects of PEMF on callus formation and maturation in the late-phase of bone healing.

Animals↗

PubMed2002

Biologic tendon fixation to metallic implant augmented with autogenous cancellous bone graft and bone marrow in a canine model.

Soft tissue attachment to a metallic prosthesis is required for the improvement of the functional outcome of endoprosthetic reconstructions. Direct tendon attachment to the metallic surface can be achieved through fibrous ingrowth, but such an attachment has a mechanical strength less than one fifth of that of a normal tendon insertion. Regeneration of a transitional structure between the tendon and the metallic surface similar to the normal morphology of a direct tendon insertion may improve the mechanical strength of the new tendon insertion. The objective of the study was to investigate the effect of placement of an interpositional autogenous cancellous bone plate augmented with bone marrow on the mechanical strength of the soft tissue attachment to the metallic surface. The insertion of the supraspinatus tendon was reattached to a porous titanium prosthesis in a canine shoulder model. An autogenous cancellous bone plate supplemented with bone marrow was positioned between the metallic surface and the tendon. Assessment of load-bearing, as a measure of functional recovery, and radiological analysis were performed at 3, 6, 9, 12, and 15 weeks. The animals were euthanized 16 weeks after surgery, and the specimens were subjected to tensile mechanical testing (six animals) and microradiographic-histologic evaluation (three animals). Functional analysis showed a 90.3% recovery of preoperative weight-bearing by 16 weeks (p < 0.05). The mineralized area around the prostheses increased by 63% over time (p < 0.05). Tensile stiffness and strength of the reconstruction were 43.6% and 42.8% of the intact tendon insertion values, respectively. These results were higher than in previous experiments using the direct tendon attachment (p < 0.01, p < 0.05, respectively) or the interpositional bone plate without marrow supplementation (p < 0.05, p < 0.05, respectively). Morphologically, the tendon reattachment site contained the basic tissue transition zones in normal tendon insertion to bone. Inductive bone grafting, supplemented with bone marrow, in the biologic augmentation of tendon anchoring onto a porous metallic prosthesis was an effective technique to increase the mechanical strength of the tendon attachment to the metallic prosthesis.

Animals↗

PubMed2002

The effect of recombinant human osteogenic protein-1 (bone morphogenetic protein-7) impregnation on allografts in a canine intercalary bone defect.

The utility of cortical allografts in repairing large bone defects is limited by their slow and incomplete incorporation into host bone. In order to determine the effects of recombinant human osteogenic protein-1 (rhOP-1) impregnation on allograft incorporation, we used a canine intercalary bone defect model. Bilateral resection of a 4 cm segment of the femoral diaphysis and reconstruction with structural bone allografts were performed. In one limb, the allograft was soaked in solution with rhOP-1 for 1 h before implantation. In the other limb, the allograft was soaked in the same solution without rhOP-1. Dynamic load-bearing, radiographic analysis, biomechanical testing, and histomorphometric analysis were conducted. Radiographic analysis showed significantly larger periosteal callus area in the rhOP-1 treated group at week 2. The rhOP-1 significantly increased allograft bone porosity and significantly increased the number of active osteons in the allografts. There were no significant differences between the rhOP-1 treated and non-treated allografts in load bearing and biomechanical analyses. These findings indicate that rhOP- I increases intercalary allograft remodeling without deleterious effects in mechanical and functional strength.

Animals↗

PubMed2002

The effect of low intensity pulsed ultrasound on regenerate bone in a less-than-rigid biomechanical environment.

The purpose of this study was to investigate effects of low intensity pulsed ultrasound (LIPU) on distraction osteogenesis in a less-than-rigid biomechanical environment in a rabbit model. A less-rigid mini-lengthener was applied and a mid-tibial osteotomy performed in 20 New Zealand White rabbits. After a 7 day latency period, the tibiae were distracted 0.5 mm every 12 hours for 10 days. Ten of the rabbits received LIPU for 20 min/day (ultrasound group) and 10 received sham LIPU (control group) from day 17 until sacrifice on day 37. Radiographs were taken weekly after distraction and the callus area was measured. After sacrifice, dual-energy X-ray absorptiometry (DEXA), torsional testing to failure, and histomorphometry were performed. On radiographs, all the treatment tibiae displayed persistent radiolucencies; however, only one of the control tibiae displayed a radiolucent interzone. Torsional strength of the treatment group was 54% of the contralateral tibia compared to 139% in the control group (p<0.008). Bone density and callus size were not significantly different between the 2 groups; however, the ultrasound group displayed a tendency towards more cartilage and fibrous tissue formation (p<0.16) and less bone (p<0.16) than controls. In a biomechanically unstable environment, LIPU appears to stimulate more cartilage formation in regenerated callus than in controls. This callus is biomechanically inferior to unstimulated callus at the early stage of healing tested. During distraction osteogenesis a sound biomechanical environment is important to achieving anticipated results.

Animals↗

PubMedDate not supplied

The effect of a doxorubicin, cisplatin and ifosfamide combination chemotherapy on bone turnover.

BACKGROUND: Use of combination adjuvant chemotherapies have improved the disease-free survival rate of tumor patients significantly. Previous experimental studies have shown that chemotherapeutic agents have negative effects on fixation of porous coated prosthesis, but the effects on normal bone turnover rate and mechanicalproperties have been reported to be minimal. MATERIALS AND METHODS: Fourteen dogs were used to study the effect of a doxorubicin, cisplatin and ifosfamide combination in normal bone turnover. We developed a safe and clinically-relevant canine model for multidrug perioperative chemotherapy that simulates current cancer treatment. The bone specimens were analyzed using microradiography, bone histomorphometry and torsional testing. The results were compared with canines that underwent a similar surgical protocol without chemotherapy. RESULTS: The results showed no differences in mechanical properties after 22 weeks of chemotherapy. The porosity, osteonal activity and mineral apposition rate of the cortical bone were unaffected. The results also showed no difference in porosity of perimeter in cancellous bone, but the mineral apposition rate was significantly reduced. CONCLUSION: The difference in mineral appostion rate of cancellous bone shows that, although the effect of temporary chemotherapy on bone may have minor effects on normal turnover and that the effect may be reversible, it causes disturbance in bone mass accumulation. This may later raise the risk for fragility fractures and osteoporosis.

Animals↗