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Biomedical subjects

Shinichi Yoshiya

Publications and source records attributed to Shinichi Yoshiya.

At least 55 records · Page 3Linked to original sources
PubMed2004

Prosthetic alignment and sizing in computer-assisted total knee arthroplasty.

We implanted 60 posterior stabilized total knee prostheses (P.F.C. Sigma, DePuy, Warsaw, USA). In 30 cases, we used a CT-free navigation system (Vector Vision, Brain LAB, Heimstetten, Germany), and in 30 matched-paired controls, we used a conventional manual implantation. We compared postoperative long-leg radiographs in the two groups. The results revealed a significant difference in favor of navigation. In addition, we compared the preoperative anteroposterior dimension of the femoral condyle with the postoperative value. While there were no significant differences in the preoperative anteroposterior dimension of the femoral condyle between the two groups, the postoperative value in the navigation group was significantly larger than that of the preoperative value. Therefore, surgeons using navigation systems should guard against the possibility of oversizing when determining the size of the femoral component.

Aged↗
PubMed2004

Effect of cyclic mechanical stretch and titanium particles on prostaglandin E2 production by human macrophages in vitro.

Early implant instability has been proposed as a critical factor in the onset and progression of aseptic loosening and periprosthetic osteolysis in total joint arthroplasties. Previous in vitro studies have reported that macrophages stimulated with cyclic mechanical strain release inflammatory mediators. Little is known, however, about the response of these cells to mechanical strain with particles, which is often a component of the physical environment of the cell. We therefore studied the production of prostaglandin E(2) (PGE(2)), an important mediator in aseptic loosening and periprosthetic osteolysis in total joint arthroplasties, for human macrophages treated with mechanical stretch alone, titanium particles alone, and mechanical stretch and particles combined. A combination of mechanical stretch and titanium particles resulted in a statistically synergistic elevation of levels of PGE(2) compared with the levels found with either stretch or particles alone. Exposure of human macrophages to mechanical stretch with particles upregulated the expression of cyclooxygenase (COX)-2 mRNA but not COX-1 mRNA, this expression resulting in a 97-fold increase in PGE(2) production compared to the nonstimulated cells. The current study is the first to investigate the effects of mechanical stretch with particles on cultured macrophages and include an investigation of the time course of PGE(2) production and COX-2 mRNA expression. Our results suggest that, while mechanical strain may be one of the primary factors responsible for macrophage activation and periprosthetic osteolysis, mechanical strain with particles load may contribute significantly to the osteolytic potential of macrophages in vitro. The synergistic effect observed between mechanical stretch and particles could accelerate implant loosening and implies that reduction in either cyclic mechanical strain or wear debris load would lead to a reduction of osteolysis.

Cyclooxygenase 2↗
PubMed2004

Traumatic anterior atlantoaxial subluxation occurring in a professional rugby athlete: case report and review of literature related to atlantoaxial injuries in sports activities.

STUDY DESIGN: This is a case report of traumatic anterior atlantoaxial subluxation occurring in a professional rugby athlete with a literature review. OBJECTIVE: To report a rare case of traumatic anterior atlantoaxial subluxation in a professional rugby athlete. SUMMARY OF BACKGROUND DATA: Atlantoaxial subluxation occurring in a professional athlete is very rare, and only two cases have been reported so far. METHODS: A 26-year-old professional rugby player sustained traumatic anterior atlantoaxial subluxation. The pathomechanism of the injury was hyperflexion. No quadriplegia existed, but severe anterior subluxation was found on functional radiographs and kinematic magnetic resonance imaging. RESULTS: Surgical fixation of C1-C2 was carried out, and no impairment was seen in his daily living, although he did not return to professional rugby. CONCLUSIONS: Anterior atlantoaxial subluxation in sports activities is very rare. The mechanism of this injury is hyperflexion, and the rupture of the transverse ligament is essential. Good prognosis has been reported; however, a return to high-level sports activities is thought to be a contraindication.

Adult↗
PubMed2004

Periosteal osteoblastoma of the distal femur.

Osteoblastomas located on the surface of the cortical bone, so-called periosteal osteoblastomas, are extremely rare. We report on a case of periosteal osteoblastoma arising from the posterior surface of the right distal femur in a 17-year-old man. Roentgenographic, computed tomographic, magnetic resonance imaging, and histologic features of the case are presented. Periosteal osteoblastoma should be radiologically and histologically differentiated from myositis ossificans, avulsive cortical irregularity syndrome, osteoid osteoma, parosteal osteosarcoma, periosteal osteosarcoma, and high-grade surface osteosarcoma. Although periosteal osteoblastoma is rare, this tumor should be included in the differential diagnosis of surface-type bone tumors.

Adolescent↗
PubMed2004

Functional comparison of posterior cruciate-retaining versus posterior stabilized total knee arthroplasty.

A prospective, randomized comparison of posterior cruciate-retaining (PCR) and posterior stabilized (PS) total knee arthroplasties (TKAs) was conducted in 20 patients who underwent bilateral TKAs for osteoarthritis. All procedures were performed by a single surgeon. One knee was implanted with a PCR TKA, and a contralateral knee with a PS TKA. Both prosthetic designs were of the same TKA series, with comparable surface geometries. Patients had a clinical and radiographic evaluation at a mean of 31.7 months for PCR TKAs and 30.6 months for PS TKAs postoperatively. There were no significant differences between the PCR and PS TKAs in postoperative knee scores. However, postoperative improvement in range of motion was significantly superior in the PS group.

Aged↗
PubMed2004

Revision anterior cruciate ligament reconstruction using the regenerated semitendinosus tendon: analysis of ultrastructure of the regenerated tendon.

In this report, we present a case of a college skier who sustained a rerupture of the reconstructed anterior cruciate ligament (ACL) 8 months after surgery in which an autogenous semitendinosus tendon graft was used. At the revision surgery, the harvested semitendinosus tendon appeared to be regrown. Thus the regenerated tendon was reharvested, and in combination with the gracilis tendon, was used as a graft. The electron microscopic examination revealed a difference in fibril diameter between the regenerated tissue and the normal tendon. Although the regenerated semitendinosus tendon could be reharvested, the feasibility of its use for revision surgery is still to be determined.

Adult↗
PubMed2004

The effect of graft sizing on osteochondral transplantation.

PURPOSE: The goal of this study was to analyze the effect of graft sizing on the histologic property of articular cartilage in autologous osteochondral transplantation. TYPE OF STUDY: Histologic analysis using an animal model. METHODS: Eighteen skeletally mature female Japanese white rabbits were used in this study and divided into 2 groups based on the surgical procedure. Group I: A cylindrical fragment (7 mm in diameter and 5 mm in depth) was harvested at the femoral condyle using the Osteochondral Autograft Transfer System (Arthrex, Naples, FL), then precisely returned to the defect from which the fragment was originally harvested. This surgical model supposes that the articular surface geometry of the osteochondral graft exactly matches that of the cartilage lesion; however, the osteochondral graft is not the same size as the defect in this model because of the surrounding gap that corresponds to the blade thickness of the chisel used to take the graft. Group II: A 1-mm larger osteochondral fragment (8 mm in diameter and 5 mm in depth) taken from the contralateral femoral condyle was transplanted to the osteochondral defect made as in group I, achieving a tight fit. Specimens were stained with Safranin-O fast green and analyzed microscopically at 4, 12, and 24 weeks after surgery. RESULTS: In group I, histologic examination revealed an increase in cartilage thickness and cell density during the implantation period. Round and polygonal hypertrophic clusters of chondrocytes with cytoplasmic vacuoles were observed. By contrast, in group II, the thickness of the articular cartilage was almost the same as that of the normal adjacent cartilage with no significant change observed. CONCLUSIONS: It is suggested that sizing of the implanted osteochondral fragment plays an important role in preserving the histologic properties of cartilage. CLINICAL RELEVANCE: This study suggests that osteochondral graft stability may influence the histologic properties of the repaired cartilage. It is preferable to implant the slightly oversized graft into the cartilage lesion in autologous osteochondral transplantation to preserve the histologic properties of cartilage.

Animals↗
PubMed2004

Expression of transcription factor Sox9 in rat L6 myoblastic cells.

Muscle-derived cells can differentiate into chondrogenic cells. In our present study, we investigated the pattern of expression of Sox9, a transcription factor known to play a key role in chondrogenesis, in a rat myoblastic cell line, L6. In addition, we evaluated expression of type II collagen and myogenic regulatory markers by reverse-transcript polymerase chain reaction. We also investigated the effect of transforming growth factor (TGF)-beta3, which is known to induce chondrogenesis, on Sox9 mRNA expression. On the first day of culture, we observed a high expression of Sox9. However, on the seventh day of culture, there was a decline in the level of Sox9 and type II collagen mRNAs and an increased expression of Myf5 and myogenin mRNAs. Sox9 mRNA expression was increased after stimulation of TGF-beta3 at 2, 6, and 24 hr. Cartilage nodules were observed in L6 cells treated with TGF-beta3 and dexamethasone. These results indicated that L6 myoblasts originally possess the capacity to differentiate into chondrogenic cells, but that capacity is lost as the cells differentiate toward the myogenic lineage. In addition, TGF-beta3 may modulate Sox9 mRNA expression in L6 cells and retain the capacity to differentiate into chondrogenic lineage.

Animals↗
PubMed2004

Lumbar instability and clinical symptoms: which is the more critical factor for symptoms: sagittal translation or segment angulation?

BACKGROUND: The relationship between radiologic instability and its symptoms is controversial. Previous authors consider flexion-extension radiographs to be of little value in evaluating instability; however, the current authors consider the variation of results in evaluating radiologic instability to be the result of limitations in previous researchers' methods. METHODS: In this report, sagittal translation and angulation at the L4-L5 segment were measured in flexion-extension films in 1,090 outpatients with low back and/or leg pain using a three-landmark measuring method. The symptoms of four groups with and without 3-mm translation and with and without 10 degrees angulation were compared for all the patients and for 280 age-matched patients using a scoring system. The age-matched patients were followed up for 4.6 years. RESULTS: Results showed that patients with > or = 3-mm translation had significantly lower scores, indicating a limitation in their daily activities due to pain, than patients < 3-mm translation; however, no difference was observed between the groups in terms of angulation. The group with > or = 3-mm translation and > or = 10 degrees angulation significantly demonstrated the lowest scores at both evaluations during the initial visit and follow-up. This group had been suffering from low back and/or leg pain the longest and had visited the hospital significantly more often than other groups. CONCLUSION: In conclusion, translation of the lumbar segment has a greater influence than angulation on lumbar symptoms. The presence of both radiologic factors could be an indicator for persistence of the symptoms.

Adult↗
PubMed2004

Spontaneously stabilized severe dysplastic spondylolisthesis without operation: long-term follow-up of a preteenage patient.

Surgical management is the accepted treatment choice for grade III or IV spondylolisthesis, and many satisfactory clinical and radiologic follow-up results have been reported. Very little, however, has been written about long-term results in preteenage patients in whom dysplastic spondylolisthesis has been treated nonoperatively, especially in those who have > or =50% displacement of the fifth lumbar vertebra on the sacrum. We report an unusual case of spontaneous stabilization of severe dysplastic spondylolisthesis in an 8-year-old girl who presented with grade III spondylolisthesis of L5-S1 and was followed up for >14 years in the absence of surgical intervention. On presentation, she complained of a restriction in forward bending and tightness of hamstrings, but she was undisturbed in her daily activities. Initial radiographs showed severe dysplastic spondylolisthesis; however, magnetic resonance imaging (MRI) performed at age 9 years showed that the amount of listhesis was much less than that seen in the initial radiograph. Routine radiographic follow-ups were chosen over early operative measures until she became a teenager. There was no change in the slip, and unusually a gradual ossification of the cartilaginous promontory of the S1 and the posterior lip of the L5 was observed. At 22 years old, the patient is asymptomatic and not conscious of her cosmetic appearance. Surgical treatment has generally been indicated for patients with grade III or IV spondylolisthesis, because slippage progression has been noted in most reported cases. However, MRI may be a tool for predicting which dysplastic spondylolisthesis cases are more likely to progress and therefore circumvent surgical intervention, while maintaining an excellent outcome.

Adult↗
PubMed2004

Synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation.

Synovial cysts of the cervical spine causing myelopathy are rare. The pathogenesis of these cysts is often attributed to degenerative changes of the facet joints or microtrauma. The authors report a synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation without a congenital anomaly or inflammatory conditions. A 72-year-old man presented with a progressive right-sided myelopathy attributed to a C1-C2 synovial cyst accompanied by atlantoaxial subluxation and C3-C6 spondylosis. Magnetic resonance imaging of the cervical spine showed a large cystic mass compressing the spinal cord located at the C1-C2 junction. A C1 hemilaminectomy, complete evacuation of the cyst contents, and posterior atlantoaxial fusion were performed, and a double-door laminoplasty was also done at C3-C6. The patient showed significant improvement of paresthesia and motor weakness of the right upper and lower extremities immediately after the operation. Synovial cysts should be considered in the differential diagnosis of an extradural mass of the upper cervical spine. Posterior fusion combined with direct excision of the cyst may be the optimum treatment of a synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation.

Aged↗
PubMed2004

Neurilemmoma in the foot as a cause of heel pain: a report of two cases.

Two cases of deep-seated neurilemmoma that arose from plantar branches of the posterior tibial nerve and caused chronic heel pain are described. At the initial examination, one case was misdiagnosed as tarsal tunnel syndrome and the other was overlooked as plantar fasciitis; both cases were treated for long periods prior to operation. Deep-seated neurilemmomas in the foot can easily be overlooked and misdiagnosed as tarsal tunnel syndrome or plantar fasciitis because of the rarity, absence of palpable mass, and similarity of symptoms to those of other frequently encountered foot disorders. Magnetic resonance imaging provides the best modality for differential diagnosis. In the present cases, surgical excision of the tumors resulted in immediate and complete relief of chronic heel pain. Surgeons should consider neurilemmoma as a cause of persistent chronic heel pain despite the rarity of the disease.

Aged↗
PubMed2003

Age distribution of three radiologic factors for lumbar instability: probable aging process of the instability with disc degeneration.

STUDY DESIGN: Cross-sectional study of 880 outpatients with low back and/or leg pain regarding age distribution of three radiologic factors. OBJECTIVES: To investigate the proportion and relationship of three individual radiologic factors with age on segmental instability in sagittal plane in consecutive age groups. SUMMARY OF BACKGROUND DATA: Previous studies revealed relationships between radiologic factors for instability and symptoms; however, little is known about the relationship between factors and age except in degenerative spondylolisthesis. METHODS: Excessive segmental motion, defined as more than 10 degrees angulation, more than 3 mm translation, and more than 3 mm slip in neutral position, at the L4-L5 segment in 880 outpatients (389 men, 491 women) with low back and/or leg pain aged from 14 to 84 years was investigated by 3 observers. The number and rate of the patients with each excessive motion were evaluated in continuous age groups of 5 years. RESULTS: The mean ages of patients with excessive angulation, translation, and slip in neutral position were 41.7, 50.0, and 62.8 years, respectively. Both rates of excessive angulation and translation showed two peak patterns demonstrating peaks in the teens and 20s groups and in the over 46 age groups; however, angulation was predominant in younger age groups and translation was predominant in older age groups. Slip in neutral position was frequently observed in age groups over 46 and increased with age. CONCLUSIONS: The presence of patients with excessive angulation and translation in younger age groups suggests they have a hypermobile segment with least degenerated discs. Different predominant patterns of these radiologic factors may reveal the probable aging process of the instability.

Adolescent↗
PubMed2003

Radiculopathy due to ossification of the yellow ligament at the lower lumbar spine.

STUDY DESIGN: A case report. OBJECTIVES: To report a rare case of a 27-year-old female with ossification of yellow ligament at the lower lumbar spine presenting radiculopathy with a drop foot. SUMMARY OF BACKGROUND DATA: The majority of cases of ossification of yellow ligament occur at the lower third of the thoracic or the thoracolumbar spine. There are only a few reports of ossification of yellow ligament in the lumbar spine and radiculopathy due to ossification of yellow ligament at L4-L5 and L5-S1 levels is very uncommon. METHODS: A 27-year-old female with a prior fracture of posterior ring apophysis of L5 presented with leg pain and a drop foot. Magnetic resonance imaging demonstrated stenosis with compression of the cauda equina at the L4-L5 and L5-S1 levels. RESULTS: Decompressive laminectomy of L5 and removal of the ossified yellow ligaments were performed. Histologic examination of en bloc specimen of ossification of yellow ligament revealed degenerative changes of the elastic fibers in the yellow ligament with adjacent chondrosis and ossification. The patient's severe leg pain disappeared completely, although the extent of the drop foot had not fully recovered at the final follow-up examination. CONCLUSIONS: The mechanism of ossification of yellow ligament in the present case was unclear. The patient did not have any previous generalized disorders besides the history of a ring apophysial fracture or any family history of treatment for ossification of the posterior longitudinal ligament or ossification of yellow ligament. Therefore, localized mechanical stress might have influenced the development of ossification of yellow ligament at lower lumbar spine.

Adult↗
PubMed2003

Ultrasound treatment of nonunion of the hook of the hamate in sports activities.

Two cases of nonunion of the hook of the hamate were treated with low-intensity pulsed ultrasound. The patients were baseball players and had been injured as a result of hitting repeatedly. Nonunion was detected on computed tomography (CT) and was exposed to ultrasound for 20 min a day for 4 months. In both cases pain at the hypothenar eminence disappeared, and bone union was confirmed on CT at the end of the ultrasound treatment.

Adolescent↗