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Shinichi Yoshiya

Publications and source records attributed to Shinichi Yoshiya.

At least 109 records · Page 6Linked to original sources
PubMed2002

Low-intensity pulsed ultrasound enhances early healing of medial collateral ligament injuries in rats.

OBJECTIVE: To investigate the effect of low-intensity pulsed ultrasound exposure on the healing of injured medial collateral ligaments. METHODS: Thirteen male Sprague Dawley rats were used in the study. After surgical transection of the bilateral medial collateral ligaments, the ligament of 1 knee received low-intensity pulsed ultrasound exposure (30 mW/cm2 for 20 minutes daily), whereas no ultrasound was applied to the contralateral knee (control side). Eight rats were killed at 12 days after surgery, and 5 rats were killed at 21 days. The bilateral knees of 5 rats were used for mechanical testing at each of the 2 periods, and 12-day specimens of the remaining 3 rats were prepared for the electron microscopic examination. The knees of 5 additional rats were used to obtain mechanical data of the normal uninjured medial collateral ligament. RESULTS: On the 12th day, the low-intensity pulsed ultrasound-treated side exhibited significantly superior mechanical properties when compared with the control side in ultimate load, stiffness, and energy absorption (P < .05). However, the treatment did not afford any mechanical advantage when tested on the 21st day. The mean diameter of the fibril was significantly larger on the treatment side than on the control side (P < .05). CONCLUSIONS: Low-intensity pulsed ultrasound exposure is effective for enhancing the early healing of medial collateral ligament injuries.

Animals↗
PubMed2002

Biphasic synovial sarcoma in a 13-month-old girl.

Synovial sarcoma is a malignant mesenchymal neoplasm which commonly occurs in the extremities of adults. We report on a 13-month-old girl with synovial sarcoma in the lateral aspect of her right ankle. The tumor was treated with total excision and 50Gy of irradiation. Histopathologic examination of the excised tumor revealed a biphasic synovial sarcoma. There was no evidence of local recurrence or distant metastasis of the tumor at follow-up examination 24 months postoperatively.

Ankle↗
PubMed2002

Conduction analysis of cement interface temperature in total knee arthroplasty.

We applied an axisymmetric model of the tibia to a finite element method and analyzed the heat conduction from bone cement in total knee arthroplasty using numerical simulation with the finite element analysis software, ABACUS. We hypothesized the thermal necrotic map of bone. Moreover, we suggested a method for preventing thermal necrosis of bone using this simulation. We adopted an initial temperature of 32?C and a cement layer of 3mm to our simulation and analyzed heat conduction. The maximum temperature into the cement layer was 65?C and 56?C at the bone-cement interface 200 sec after the start of heat generation. Bone necrosis was observed approximately 2mm from the bone-cement interface. To thin the cement layer, the maximum temperature and bone necrotic area reduced. At a cement layer of less than 1mm no bone necrotic area was observed. To lower the initial temperature of the bone surface, the maximum temperature and bone necrotic area was also reduced. At an initial temperature of less than 28?C we did not find any bone necrosis. Even if we hypothesized pouring cold water around the prosthesis, the maximum temperature did not reduce at any time, neither did the necrotic area reduce. We should make the cement layer as thin as possible and cool the bone before cementing to prevent thermal bone necrosis.

Arthroplasty, Replacement, Knee↗
PubMed2002

The effect of the small and unstable autologous osteochondral graft on repairing the full-thickness large articular cartilage defect in a rabbit model.

We have investigated the effect of the insufficient autologous osteochondral graft on healing of the large articular cartilage defect using a rabbit model. An osteochondral defect, 7 mm in diameter, was made on the patellar groove of the femoral condyle and repaired with two surgical procedures: Group I, the osteochondral fragment as half as the defect was grafted. The graft was unstable and the size of the graft was smaller than the defect. This is a model of the insufficient autologous osteochondral graft to the large articular cartilage defect; Group II, the defect was left empty. At 2, 4, 12, and 24 weeks after the surgery, the specimens were analyzed macroscopically and histologically. To evaluate the microscopic morphology, a histologic grading scale composed of 5 categories was used. In Group I, although the graft sank a little, a grafted cartilage survived and the reparative fibrous tissue filled the defect covering implanted cartilage. In contrast, in Group II, the defect was only partially covered by fibrocartilaginous tissue with a faintly staining matrix. Throughout the entire observed periods, the scores of the repaired cartilage in Group I are significantly higher than those in Group II. Even the half size of osteochondral graft has an effect to reduce the size of the cartilage defect such as the spacer and leads to better healing compared to the cartilage defect untreated. In case that it is hard to transplant an optimal osteochondral graft because of large cartilage lesion, even the small and unstable osteochondral plug should be transplanted.

Animals↗
PubMed2002

Titanium-alloy particles induced cyclooxygenase-2 in human macrophage-like cells in vitro.

Prostaglandin E2 (PGE2) has been reported to be an important mediator in aseptic loosening and/or periprosthetic osteolysis in total joint arthroplasties. Previous studies have reported that human macrophages stimulated with particles in vitro release PGE2. However, they have not shown the expression of cyclooxygenases (COX) which are rate-limiting enzymes of PGE2 synthesis. We hypothesized that PGE2 production by activated macrophages is dependent upon the induction of COX-2, not upon the constitutive isozyme, COX-1. When we evaluated the expression of COX-1 and COX-2 in titanium-alloy particle-stimulated human macrophages, the expression of COX-2 mRNA was up-regulated by the particles, on the other hand, the expression of COX-1 mRNA was not affected. In addition, NS-398, a COX-2 inhibitor drastically suppressed up-regulated PGE2 production by the particles. These results provide strong evidence that PGE2 production by particle-stimulated macrophages is dependent upon the induction of COX-2, not COX-1.

Alloys↗
PubMed2001

Evaluation of healing of the injured posterior cruciate ligament: Analysis of instability and magnetic resonance imaging.

PURPOSE: Knees with an acute posterior cruciate ligament (PCL) injury and soft endpoint on posterior drawer test often develop less instability and a firm endpoint at later follow-up. This type of healing is rarely seen in the acutely injured anterior cruciate ligament (ACL) and seems to be a unique feature of healing for PCL injury. The purpose of this study was to explore the healing process of the injured PCL by means of instability measurement and magnetic resonance imaging (MRI). Type of study: Consecutive sample. METHODS: Forty-eight acute PCL deficient knees were followed up and evaluated. We evaluated the detection of a so-called firm endpoint using a posterior drawer test. We also determined the degree of posterior sag and categorized them as 3 grades. Quantitative assessment of total anteroposterior (AP) translation of the tibia with a KT-1000 knee arthrometer (MedMetric, San Diego, California) was performed by manual maximum AP drawer test with the knee flexed 70 degrees. The continuity of the PCL was evaluated with sagittal and coronal T1- and T2-weighted MRIs. RESULTS: Thirty-three (69%) cases exhibited a so-called firm endpoint with a posterior drawer test. These cases showed statistically less total AP translation (mean, 7.0 mm) in KT-1000 evaluation, compared with 15 cases without an endpoint (mean, 11.9 mm). In addition, 36 cases (75%) with continuous low-intensity MRI showed statistically less AP translation (mean 7.6 mm), compared with 12 cases (mean 11.4 mm) with disrupted PCL image. CONCLUSIONS: These results suggest that a high percentage of acutely injured PCLs are likely to develop somewhat slack but continuous ligament-like tissue, and this continuous PCL-like tissue might function as a posterior restraint of the tibia to certain extent. The elongated but continuous PCL might partly explain the relatively favorable prognosis of this injury.

Journal Article↗
PubMedDate not supplied

Magnetic resonance delineation of the anterior cruciate ligament of the knee: flexed knee position within a surface coil.

The purpose of this study was to evaluate the effect of the knee position at three different flexion angles in magnetic resonance (MR) delineation of the anterior cruciate ligament (ACL) in the knee and to determine the optimal knee position. Thirteen knees of normal volunteers were examined at 15 degrees, 30 degrees, and 45 degrees of flexion with a surface coil, and three sets of obtained oblique sagittal MR images were evaluated by four observers. MR images at 30 degrees of knee flexion most clearly delineate compared with those at 15 degrees and 45 degrees of knee flexion. We recommended examining the knee in 30 degrees of flexion.

Adult↗
PubMedDate not supplied

Subacute osteomyelitis of long bones: diagnostic usefulness of the "penumbra sign" on MRI.

Although subacute osteomyelitis of long bones is not uncommon, it is usually confined to metaphysis. Two unusual cases of subacute osteomyelitis that traversed a growth plate are described. There may be some radiological difficulties in distinguishing it from other malignant or benign lesions. On magnetic resonance (MR) imaging, both of the present cases showed characteristic four-layered appearance and the penumbra sign. These characteristic findings on MR imaging are considered to facilitate establishing the radiologic diagnosis.

Adolescent↗
PubMedDate not supplied

Evaluation of hamstring strength and tendon regrowth after harvesting for anterior cruciate ligament reconstruction.

BACKGROUND: It is generally thought that tissue regeneration and good functional recovery can be expected after anterior cruciate ligament reconstruction using the hamstring tendons. However, persistent strength deficit in deep knee flexion has also been reported. HYPOTHESIS: Morphologic regeneration of the harvested hamstring tendon is not necessarily associated with its functional recovery. STUDY DESIGN: Retrospective follow-up study. METHOD: Twenty-eight patients who underwent anterior cruciate ligament reconstruction with hamstring graft were evaluated after a minimum period of 2 years. Status of tendon regrowth was assessed by magnetic resonance imaging. To specifically analyze the functional deficit after graft harvest, the isometric hamstring strength was examined in a sitting position at 90 degrees of flexion and a prone position at 90 degrees and 110 degrees of flexion. Then, the strength data were correlated with the extent of tendon regeneration. RESULTS: In 22 of the 28 patients, a regrowth of the semitendinosus tendon was found, whereas regeneration of the gracilis tendon was observed in 13 patients. In the evaluation of hamstring strength, the isometric peak torque was reduced to 86.2%, 54.6%, and 49.1%, respectively, in the aforementioned 3 postures as compared with the contralateral side. CONCLUSIONS: Significant functional deficit of hamstring strength remains regardless of morphologic regeneration.

Adolescent↗
PubMedDate not supplied

Scrape and fine-needle aspiration cytology of elastofibroma.

BACKGROUND: Cytological findings of elastofibroma have rarely been reported and, to the best of our knowledge, have been illustrated in only 4 patients in the English language literature. MATERIALS AND METHODS: We retrospectively reviewed fine-needle aspiration biopsy (FNAB) and scrape smears in 5 cases of elastofibroma. RESULTS: All the lesions were typically located between the rib cage and the scapula. The cytological smears consisted of mature adipocytes, fibroblasts, collagen fibers, globular bodies and characteristic "braid-like" or "fern-like" structures, revealing degenerative elastic fibers. All the smears were specifically diagnosed as elastofibroma in combination with clinical and radiological findings. CONCLUSION: FNAB smears of elastofibromas may be hypocellular due to their densely fibrous nature and therefore diagnostic material may often be overlooked. Careful evaluation of the background of the smears coupled with full knowledge of the clinical and radiological findings, including magnetic resonance imaging, is required to establish the correct diagnosis.

Adipocytes↗
PubMedDate not supplied

Reimplantation of autoclaved or irradiated cortical bones invaded by soft tissue sarcomas.

BACKGROUND: Bone defects after excision of malignant bone and soft tissue tumors are usually reconstructed by autogenous bone grafting or allografting. PATIENTS AND METHODS: We treated 2 patients who had soft tissue sarcomas with bone involvement, the first by excision and reimplantation of the hemicortical autogenous cortical bone graft after autoclaving and the second with intraoperative irradiation. RESULTS: In both patients, postoperative follow-up radiographic studies showed incorporation of the implanted bones into the host bones within 12 months. Biopsy of the implanted bone performed 3 years after surgery showed many viable osteocytes, and blood vessel invasion into Harversian canals. No complications regarding the reconstructive techniques were observed during the postoperative period. CONCLUSION: The reimplantation of autogenous cortical bones after autoclaving or irradiation is a useful reconstructive method for partial bone defects in soft tissue tumor surgery.

Adult↗
PubMedDate not supplied

Fine-needle aspiration biopsy in the initial diagnosis of bone lesions.

BACKGROUND: The diagnostic role of fine-needle aspiration biopsy (FNAB) of bone lesions is not yet fully understood. The aim of this study was to examine the diagnostic accuracy and reliability of FNAB of bone lesions. MATERIALS AND METHODS: FNAB smears of 73 lesions obtained from 70 patients with bone lesions were retrospectively reviewed randomly, combined with clinical and radiological findings. RESULTS: Of the 73 FNAB cases analyzed, 67 (92%) were considered to be adequate for diagnosis. The sensitivity and specificity were 100% and 86%, respectively. The positive and negative predictive values were 94% and 100%, respectively. The specific FNAB diagnoses were correct in 63% of the benign group, 89% of the malignant group and 17% of the nonneoplastic group. CONCLUSION: FNAB of bone is a simple, safe, rapid, reliable and cost-effective diagnostic procedure. FNAB is suggested to be helpful in the workup and management of patients with bone lesions.

Adolescent↗
PubMedDate not supplied

Management of liposarcoma occurring in pregnant women.

BACKGROUND: The coexistence of pregnancy and liposarcoma is rare. Only 12 cases of pregnancy-associated liposarcoma have previously been reported in the English-language literature. MATERIALS AND METHODS: We present two cases of liposarcoma occurring in pregnant patients: one myxoid liposarcoma in a 29-year-old woman at 29 weeks' gestation; another well-differentiated liposarcoma in a 44-year-old woman at 22 weeks' gestation. RESULTS: The first patient's infant was delivered by cesarean section after the confirmation of pulmonary maturity of the fetus. The patient was subsequently treated with chemotherapy and radiotherapy. The second patient awaited delivery until 32 weeks' gestation with no treatment of the tumor because she had a low-grade sarcoma. After cesarean section, surgical treatment followed. CONCLUSION: Treatment of sarcomas occurring during pregnancy is difficult. Both mother and fetus should be appropriately managed, depending on the trimester at the time of diagnosis and the histological type and grade of the tumor.

Adult↗