Biomedical subjects

Yomei Tachibana

Publications and source records attributed to Yomei Tachibana.

5 recordsLinked to original sources

PubMed2004

Intra-articular ganglia arising from the posterior joint capsule of the knee.

Magnetic resonance imaging (MRI) is an effective method to evaluate cystic lesions of the knee. Intra-articular ganglia of the knee joint was considered to be rare before the advent of MRI. However, because an MRI is often used to diagnose knee pathology, the reported prevalence of intra-articular ganglia has increased. We describe two cases of an intra-articular ganglion arising from the posterior joint capsule. Both cysts appeared to be arising from the posterior cruciate ligament by both MRI as well as arthroscopy through a lateral infrapatellar portal. However, arthroscopy through a posteromedial portal revealed the cysts to originate from the posterior joint capsule. It suggests that some of the ganglion arising from the posterior cruciate ligament reported in the literature might actually be from the posterior joint capsule. To prevent recurrence of a ganglion cyst, when preoperative MRI shows the mass to be located posterior to the cruciate ligaments, we recommend that the relationship of the ganglion cyst to the posterior joint capsule be evaluated at arthroscopy through the posteromedial or posterolateral portal.

Adult↗

PubMed2003

Tissue response to porous hydroxyapatite ceramic in the human femoral head.

We describe pathohistological findings of the human femoral head after it was grafted with hydroxyapatite (HA) and allogenic bone. The femoral head was removed because of the recurrence of a giant cell tumor 15 months after the graft. Histological investigation revealed that the entire surface of the HA granules was completely surrounded by the bone in the periphery of the grafted area; in some areas granules were partly in contact with the existing bone, and the rest were surrounded by fibrous tissue. There was no intervening layer of fibrous tissue between the granule surface and the bone where they were in direct contact. Pores were completely filled with fibrous tissue, partially filled with bone in the periphery of the pores, or completely filled with bone. Undecalcified histology revealed the formation of osteoid and ossification at the site where fibrous tissue infiltrated the pores. These findings indicated continued ingrowth of new bone into the HA pores. Under a scanning electron microscope, the surfaces of the granules showed clear demarcation in vitro, but it became less smooth, indicating in vivo changes. Although no foreign body reaction to the HA was noted anywhere, the HA surface appeared to be subject to a biodegradation process.

Biocompatible Materials↗

PubMed2003

Vascularized synovial flap promoting regeneration of the cryopreserved meniscal allograft: experimental study in rabbits.

The purpose of this investigation was to evaluate whether a vascularized or free synovial flap or a fibrin clot can promote regeneration of meniscal allograft in the rabbit. Seventy-eight mature New Zealand white rabbits were used. The harvested medial meniscus for the allotransplantation was frozen and stored at -80 degrees C for 2 weeks. After resecting the medial meniscus, an allogenic meniscus was transplanted in the anatomical position (group A). The surface of the graft was covered by a vascularized synovial flap (group B), a free synovial flap (group C), or a fibrin clot (group D). The animals were killed 4, 6, 8, 12, and 16 weeks after transplantation, and the transplants were examined by gross inspection, histology, and microangiography. Connective tissue infiltration into the matrix of the graft was found to begin at 6 weeks (2/5 menisci) and to be complete at 8 weeks (5/5 menisci) in group B, whereas it began at 8 weeks (1/5) in group A. The newly formed repair tissue developed from the synovial tissue and consisted of connective tissue at the beginning and fibrocartilage later. The fibrocartilage had appeared at 8 weeks (3/5) in group B but not yet in group A (0/5). A free flap or fibrin clot coverage resulted in delayed revascularization compared to a vascularized synovial flap, but both tended to achieve faster revascularization than the controls. We concluded that regeneration of allografted meniscus with a vascularized synovial flap occurs earlier than under other conditions. Thus, allografts with synovial implantation may be considered for management of the meniscectomized knee.

Animals↗

PubMed2003

Acetabular labrum entrapment following traumatic posterior dislocation of the hip.

In traumatic dislocation of the hip with or without a fracture of the acetabular rim, complete anatomical reduction might be prevented by a bone fragment or infrequently by a soft tissue block, such as a torn acetabular labrum, ruptured capsule, or round ligament. We report a rare case of a tear in the acetabular labrum that prevented complete reduction of the dislocated hip. A 26-year-old man suffered posterior dislocation of the right hip, which was reduced under general anesthesia. The postreduction radiograph showed that the reduction was not complete, and a thin bony fragment was observed in the joint space in the weight-bearing area. Open reduction was performed 11 days later. We found a free bone fragment in the joint space, which was removed. The postoperative radiograph still did not show complete reduction of the hip. A large defect in the contrast medium was shown in the widened joint space by arthrography, which revealed the existence of the soft tissue interposition. We then performed a second operation and learned that the acetabular labrum was widely detached from the anterior to the posterior acetabular rim and was lying deep within the acetabulum. This detached portion of the labrum was excised, and the hip was reduced. The radiograph obtained during surgery then showed complete, concentric reduction. We missed the diagnosis clinically and radiologically at the first operation, proving how important it is to obtain an accurate radiological diagnosis in the operating room.

Acetabulum↗

PubMed2003

Discoid medial meniscus.

A discoid medial meniscus is an extremely rare anomaly. We present 4 cases of symptomatic discoid medial meniscus. Furthermore, magnetic resonance imaging (MRI) of the unaffected knee was obtained in 3 cases, and 1 patient had bilateral discoid medial menisci as well as a unilateral discoid lateral meniscus proven by MRI. Another patient had bilateral discoid medial menisci. In one of the other 2 cases, an MRI of the unaffected knee was not obtained. However, in the involved knees of both cases, medial and lateral menisci were discoid. The incidence of bilateral discoid medial menisci is unknown. In the past, the diagnosis of a discoid meniscus was made with an arthrogram or at arthrotomy. Therefore, whether some of the unilateral cases reported in the literature might have been bilateral is unknown. The reported prevalence of bilateral discoid medial menisci will probably increase, because when a discoid medial meniscus is encountered currently, an MRI is used to find knee disorders, including in the contralateral knee. Axial multiplanar gradient-recalled-echo imaging could provide images of the discoid meniscus, depicted in its entirety in one section. This would make the recognition of a discoid meniscus simple.

Abnormalities, Multiple↗