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Biomedical subjects

Y Matsusue

Publications and source records attributed to Y Matsusue.

43 records · Page 3Linked to original sources
PubMed1992

In vitro and in vivo studies on bioabsorbable ultra-high-strength poly(L-lactide) rods.

Ultra-high-strength poly(L-lactide) (PLLA) rods were fabricated using a drawing technique. Rods with a diameter of 3.2 mm and a draw ratio of 2.5:1 showed initial bending strength and modulus values of 240 MPa and 13 GPa, respectively. The purpose of this study was to investigate the in vitro and in vivo degradation of PLLA rods with a draw ratio of 2.5:1. The greater the rod diameter, the longer the bending strength was maintained in phosphate buffered saline at 37 degrees C. The bending strength retention of rods (diam. 3.2 mm) implanted in the subcutis of rabbits was almost equal to that of rods in the in vitro study, while those rods implanted in the medullary cavity of rabbit femora showed a slightly lower bending strength retention. Molecular weight was reduced to the greatest extent in the medullary cavity, followed by in the subcutis and in vitro. The weight of PLLA rods in the medullary cavity was reduced by 22% at 52 weeks and by 70% at 78 weeks after implantation. Histologically, no inflammatory or foreign body reaction was observed in the medullary cavity for 52 weeks. The drawn PLLA rods maintained a bending strength exceeding that of human cortical bone in the medullary canal for a period of 8 weeks, suggesting that the drawn PLLA rods may be useful in the repair of fractured human bones.

Absorption↗
PubMed1992

Severe metallosis due to abnormal abrasion of the femoral head in a dual bearing hip prosthesis. A case report.

The authors report on a patient with a case of severe metallosis due to an abnormal abrasion of the femoral head. A primary arthroplasty was performed using a dual bearing hip prosthesis with acetabular bone grafting by ceramic screws. At the time of the revision surgery the synovia was black, and an analysis using a scanning electron microscope and scanning electron microscope-electron probe micro-analyzer revealed numerous small particles of small alumina ceramic on the inner surface of the bearing insert of high-density polyethylene. These particles, which came from the broken ceramic screws due to proximal migration of the prosthesis, scraped the femoral head away. A line and area analysis of the black synovia revealed that the synovia contained metal particles of a cobalt-chromium alloy as well as a cobalt ion. The patient's serum showed elevated concentrations of cobalt, chromium, and molybdenum that dramatically reduced 2 months after the revision surgery.

Adult↗
PubMed1991

Arthroscopic resection of the shelf (mediopatellar plica) in the knee under local anesthesia in outpatient clinic.

Forty-two knees with symptomatic mediopatellar plicae (shelves) were managed using the operative method under local anesthesia. Of these, thirty-one knees had isolated mediopatellar plicae, and eleven had other associated intra-articular pathologic condition, such as meniscal tear, lateral patellar tracking, osteochondritis dissecans, and minor osteoarthritic changes. The clinical results were excellent or good in thirty-seven (88%) patients, fair in five patients after an average follow-up of twenty-five months. No case showed deterioration after surgery. Because there are no definitive criteria for the indication of shelf resection, arthroscopic resection of the shelf under local anesthesia is recommended if there is any possibility of it being the cause of knee pain.

Adolescent↗
PubMed1991

Effective treatment by orthosis of dislocation of the patella associated with Down's syndrome. A report of case.

The authors reported a case of recurrent dislocation of the patella associated with Down's syndrome. As for treatment, it is important to consider the levels of intelligence and daily activity, severe obesity, and certain internal medical conditions associated with this disease. Primary orthotic treatment is recommended for subluxation or reducible dislocation of the patella.

Adolescent↗
PubMed1991

Biodegradable screw fixation of rabbit tibia proximal osteotomies.

The purpose of this study was to evaluate a biodegradable poly(L-lactide) (P-L-LA) screw for osteosynthesis under a load-bearing condition. A proximal tibial osteotomy on 25 rabbits was fixed with a biodegradable screw made of P-L-LA. A follow-up study was done at 1, 2, 4, 8, and 16 weeks. In another 25 rabbits, the tibial osteotomy was fixed with stainless steel (SUS) screws of the same size as the P-L-LA screws with a similar follow-up period. Radiographic, histological, microradiographic, and oxytetracycline-labeling studies showed healing of the osteotomy within 4 to 8 weeks. The displacement of fragments and the mass of newly formed bone around the screws were measured by histomorphometric analysis. There was no significant difference in the displacement of the fragments in these two groups and new bone was more abundantly detected in the P-L-LA group than in the SUS group. Histologically, no inflammatory lesion was detected in either group. All osteotomies united without delay and the displacement was minimal, although no external support was applied and the rabbits were allowed to move freely after the operation. The results of this study suggest a possible use for a P-L-LA screw in the clinical treatment of human bone fractures.

Animals↗
PubMedDate not supplied

Anti-tumour effects of localized hyperthermia on an experimental bone tumour using an intramedullary nail.

A new localized hyperthermia system for an experimental bone tumour in the rabbit tibia was developed. This system was composed of an induction coil, generator and a Kirschner wire, which was inserted into the medullary canal of the tibia as a heat-generating ferromagnetic implant. The metastatic bone tumour model was created by implantation of VX2 carcinoma in the medullary canal of the tibia diaphysis. The days after VX2 implantation, hyperthermia was induced for 50 min. Three weeks after the treatment, rabbits were sacrificed for histological and radiological evaluation. According to the semi-quantitative scoring system, anti-tumour effects of the single dose of hyperthermia was noted radiologically (p < 0.01) and histologically (p < 0.05) where the temperature was at a sufficient level to cause hyperthermia (> 42.5 degrees C). This new heating method, which is relatively simple and clinically applicable, appears to be promising for the treatment of metastatic tumours of the long bone.

Animals↗