Noriya Akamatsu

Arthroscopic surgery of the hip joint

Hip arthroscopic examination of 196 joints was performed in 104 patients treated during the past 4 years. Of these, 11 joints were treated by arthroscopic surgery. We have developed a technique using a two-directional approach that facilitates a global view of joint areas and allows simpler performance of surgical procedures. Removal of loose bodies, joint debridement in osteoarthritis, and synovectomy in rheumatoid arthritis are good indications for arthroscopic surgery of the hip joint. Short-term follow-up was satisfactory, and a reduction of pain was obtained in all patients. Although the joint space of the hip is narrower and the operative technique is more difficult to perform than in the knee, we believe that arthroscopic surgery of the hip is a suitable method in selected cases.

Cisplatin (CDDP) specifically induces apoptosis via sequential activation of caspase-8, -3 and -6 in osteosarcoma

Purpose: Osteosarcoma is a common malignant tumor. The first choice of treatment plan for osteosarcoma is chemotherapy. In particular, preoperative chemotherapy is most important in clinical treatment in orthopedics. In these chemotherapies, multiple anticancer drugs such as Adriamycin (ADM), CDDP, cyclophosphamide (CPM), methotrexate (MTX) and vincristine (VCR) are commonly used in combination. Recently, anticancer drugs have been shown to trigger apoptosis in various cancer cells. However, many studies on this topic have been examined using leukemia cell lines, and many kinds of cancer cells established from solid tumor are resistant to the induction of apoptosis by anticancer drugs. So in this study, we examined the effects of the anticancer drugs ADM, CDDP, CPM, MTX and VCR on osteosarcoma cells in vitro. We also examined the signaling pathways of each anticancer drug by studying the induction of apoptosis and activation of caspases in the osteosarcoma cells. Methods: We examined the effects of the anticancer drugs ADM, CDDP, CPM, MTX and VCR, which are used clinically for the treatment of osteosarcoma, on cells of the human osteosarcoma (HOS) cell line. The cytotoxic effects of the anticancer drugs were evaluated using the MTT assay. We used both flow cytometry and activation of caspases to confirm the induction of apoptosis in the HOS cells. To dissect the pathway of the caspase cascade in apoptosis in HOS cells, we used the tetrapeptides YVAD-CHO, DMQD-CHO, VEID-CHO and IETD-CHO, which selectively inhibit caspase-1, -3, -6 and -8, respectively. Results: ADM, CDDP, CPM and VCR, but not MTX, induced death of HOS cells in a dose-dependent manner. CDDP at 10 μM, CPM at 7.5 μM, ADM at 20 μM and VCR at 150 μM caused 80% cell death of HOS cells after 12 h. However, the percentages of apoptotic cells were 5.6% (medium alone), 75.9% (CDDP), 20.0% (CPM), 22.2% (ADM), 20.5% (VCR) and 13.1% (MTX). In addition, direct measurement of caspase-3 activity revealed that CDDP but not the other drugs activated caspase-3 in HOS cells. These analyses revealed that only CDDP induced apoptosis of HOS cells via activation of caspases. Furthermore, DMQD-CHO, VEID-CHO and IETD-CHO inhibited CDDP-induced apoptosis of HOS cells, suggesting that caspase-3, -6 and -8 are involved in the signaling pathway of CDDP-induced apoptosis. In contrast, none of the caspase inhibitors inhibited cell death induced by the other anticancer drugs. Conclusions: This study demonstrates that CDDP specifically induces apoptosis via activation of caspases and the other anticancer drugs induce death of HOS cells via different signaling pathways. It also demonstrates that caspase-8 is a key molecule in the earliest stage of the signaling pathway of CDDP-induced apoptosis of HOS cells, and caspase-3 works downstream of caspase-8.

Expectations for medical and healthcare robotics

It is no exaggeration to say that we are up against an inordinate lack of hospital staff, with a shortage of labour in non-medical as well as in specialized medical fields in Japan. For these reasons, the necessity for medical and healthcare robotics is examined in this study in order to qualitatively improve medical treatment. In addition, clinical applications of medical and healthcare robotics are also described.

Histological study of articular cartilage in experimental rat knee arthritis induced by intracapsular injection of cationic polyethyleneimine

Degeneration of proteoglycans and abnormalities in their metabolism have been assumed to be critical at an early stage of osteoarthritis. To clarify a trigger mechanism of osteoarthritis, anionic sites of knee articular cartilage were blocked by intracapsular injection of cationic polyethyleneimine of 2000 or 70 000 molecular weight (MW) into rat knee joints. Experimental or normal rats were examined by gross observation, roentgenography, cytokine interleukin-1β (IL-1β) assay, and light or electron microscopy. In both groups with the polyethyleneimine injection, the rats showed temporarily limping and swelling of their knee joints. By light or electron microscopic studies, knee articular cartilage was found to be degenerated at an early stage, but IL-1β was within normal levels. At 2, 4, or 6 months, the deformity of the knee joints was obvious by roentgenography. Degeneration and hypofunction of proteoglycans might be related to the ultrastructural changes of articular cartilage at an early stage, though the inflammatory cytokine was not involved. At later stages the pathophysiology of the knee joints advanced chronically to typical osteoarthritis, which was more radically induced by the large molecular polyethyleneimine (70 000 MW). The functional impairment of anionic sites is a key point for elucidating the mechanism of osteoarthritic development in this animal model.

A clinical study of the results of cementless total hip replacement.

SummaryWe introduce our total hip prosthesis, its operation technique, and report the clinical results. Ours does not use bone-cement, but its design, together with the use of original bone and new bone formation surrounding it, results in a biological anchoring.Since 1978, we developed for this new type of total hip prosthesis 6 sizes of stem to fit more rigidly within the intramedullary canal of femur. The new femoral component also has larger notches on its surface than did the old one.Our results of 144 cases (147 joints) ranging from 2 to 10 postoperative years giving an average of 4.4 years, are quite satisfactory.Blood loss during the operation is as little as 480 ml. The few complications observed differ from those of the Charnley type, and will be reduced greatly when the operation is yet more cautiously and skillfully done.Unilateral replacement in bilaterally affected patients improved the condition of the unoperated side in 30% of the cases.ZusammenfassungWir stellen unsere Hüftgelenk-Totalprothese und ihre Operationstechnik vor und geben einen Bericht über die klinischen Ergebnisse. Unsere Prothese wird nicht mit Zement fixiert. Ihre Gestaltung führt jedoch, gemeinsam mit der Ausnutzung des natürlichen Knochens und einer umgebenden Knochenneubildung, zu einer direkten Fixation.Seit 1978 haben wir fur diesen neuen Prothesentyp 6 Schaftgrößen entwickelt, um sie fester in die Femurmarkhöhle einzupassen. Die neue Kopfprothese hat an ihrer Oberfläche auch größere Vertiefungen als die alte.Unsere Ergebnisse von 144 Fällen (147 Gelenke), die zwischen 2–10 Jahren and durchschnittlich 4,4 Jahre nach der Operation liegen, sind durchaus zufriedenstellend.Der Blutverlust während der Operation betrug nur 480 ml. Die wenigen beobachteten Komplikationen unterscheiden sich von denen der Charnley-Prothese und werden wesentlich herabgesetzt, wenn die Operation sorgfältiger and mit mehr Erfahrung ausgeführt werden wird.Die einseitige Operation beim doppelseitigen Hüftgelenkbefund verbesserte die Verhältnisse an der nichtoperierten Seite in 30% der Fälle.

The direct fixation system of total hip prosthesis

SummaryThere are two methods for the fixation of prostheses to bone; one is a method using bone cement and another is the direct fixation of the prostheses to bone. Four types of animal experiments were performed to compare the two methods of fixation. A small pyramid shaped test piece was used to compare the fixation capacity of the socket spike. Also, a special test piece was used to study the time of bone formation, to check the fixation capacity of bone bar formation occurring in the hole in the based part of the prosthetic component. Furthermore, models of prosthetic stem and socket were made and attached to the femur and ilium of dog to perform fixation tests and fatigue tests. As a result, any of the tests proved that the direct fixation method without the usage of bone cement was superior to the fixation method using bone cement.ZusammenfassungVier tierexperimentelle Anordnungen wurden ausgeführt, um die Prothesenverankerung im Knochen mit und ohne Zement zu vergleichen. Verschiedene Prüfkörper wurden benutzt, um die Festigkeit der Verankerung und den Ablauf der Knochenanlagerung zu untersuchen. Außerdem wurden Modelle von Prothesenschäften und Prothesenpfannen für Verankerungs- and Ermüdungsuntersuchungen verwendet. Alle these experimentellen Untersuchungen haben ergeben, daß die direkte, zementfreie Verankerung der Implantate jener mit Knochenzement überlegen ist.

A cementless system of total hip prosthesis

SummaryIt is essential that the prosthetic material should not be harmful to the human body, it should be strictly fitted to the body and it should have sufficient durability.To investigate those conditions of an artificial joints as mentioned above, it is important to have experimental studies using a model of the artificial joint in animals instead of a simulator.The authors have developed their own total hip prosthesis for a dog since 1970. These prostheses were fixed to the bone without bone cement.These dogs were killed periodically from 8 weeks to 3 years after surgery of total hip replacement.Not only were pathohistological studies on the joint capsule and bony tissue of the femur surrounding the prosthesis performed, but also scanning electron microscopic examination on capsule and the surface of the prosthetic head were performed.The results were excellent. Ther was no loosening or wear when the new type of acetabular socket with large spikes was used. On the other hand, in the case of the old type socket with its smooth surface and smaller spikes, loosening of the socket and prosthetic stem occurred within one year after surgery.ZusammenfassungEs ist entscheidend, daß das Material eines Kunstgelenkes sich im menschlichen Organismus inert verhält, daß es im Körper sehr genau eingepaßt wird and daß es eine ausreichende Haltbarkeit aufweist.Für die Erforschung dieser Bedingungen ist es wichtig, mit einem Modell des Kunstgelenkes tierexperimentelle Untersuchungen durchzuführen, anstatt einen Simulator zu verwenden.Die Autoren haben seit 1970 ihr eigenes Modell einer Hüftgelenk-Totalprothese für den Hund entwickelt. Diese Prothese wird zementfrei im Knochen verankert. Die Versuchstiere wurden 8 Wochen bis 3 Jahre nach der Prothesenimplantation in regelmäßigen Zeitabständen der Untersuchung zugeführt. Es erfolgten nicht nur histologische Untersuchungen der Gelenkkapsel und des Knochengewebes aus der Umgebung der Implantate, sondern auch die Oberfläche der Gelenkkapsel und der. Prothesenkomponenten wurden im Raster-Elektronenmikroskop überprüft.Die Ergebnisse waren hervorragend. Bei dem neuen Pfannentyp mit großen Verankerungsdornen waren weder Lockerung noch Abrieb erkennbar. Demgegenüber zeigten die Fälle mit dem alten Pfannentyp, mit der glatten Fläche und den kleinen Verankerungsdornen, Lockerungen beider Prothesenkomponenten schon innerhalb eines Jahres.

—Overview— Ideal Stem Design for Cementless Total Hip System

To improve cementless stem design to achieve long-term stability, simulations using graphic processing systems or cadaver specimens, and biomechanical analyses, using rigid body spring models (RBSM) or finite element models (FEM) have been used. Simulations using graphic processing systems or cadaver specimens are useful for investigating the shape or size of the stem which provides stem press fit into the medullary canal. These methods, however, have a disadvantage in that, when they are used, it is not possible to comprehensively evaluate biomechanical stability, in terms of evaluating such factors as the resection angle of the femoral neck, the stem length, and the absence or presence of calcar femorale, which greatly influence this stability. Biomechanical analysis of computer simulations using the RBSM, on the other hand, makes it possible to comprehensively evaluate biomechanical stability in terms of these factors. Further, the results obtained for such simulations are so reliable as to be consistent with clinical results. Against this background, we performed computer simulations, using the RBSM, to develop a new cementless stem, the model Y 2, which was used for 48 hips in 48 patients. This model has a 35° resection angle of the femoral neck and a stem length of 178 mm The stem has a smooth surface with several longitudinal grooves. In the 29 hips of 29 patients who were followed-up for more than 2 years there was an excellent postoperative course, only 3 patients (10%) being affected by thigh pain. Roentgenographic findings showed no shifting or sinking of the stem and a clear zone less than 2-mm-wide was observed in only seven cases. Based both on our clinical results in patients who received model Y 2 replacements, and on the advantages gained in terms of comprehensively evaluating biomechanical stability, we believe that biomechanical analysis of computer simulations, using the RBSM, is a very useful method for the evaluation of the ideal design for a cementless stem.

Biomechanical Features of Various Cementless Total Hip Replacement Systems

The selection of an implant and the surgical placement of a prosthetic component in total hip replacement are based on limited radiographic and clinical information. To optimize surgical outcome and anticipate intraoperative problems, computer-aided simulation/analysis software was developed based on the rigid body spring model (RBSM), using plane radiographs (two-dimensional [2-D] analysis) to obtain implant/bone interface stress, ligamentous tension, and relative displacement for bony segments and implants. In the study of our total hip replacement (THR) system which features three spikes on the socket, the main assessment criterion used was an implant fixation index based on implant/bone interface stress and relative displacement of the prosthesis in reference to bone. The computer simulation was consistent with the clinical results for our cementless THR system and it showed that implant design and placement significantly affected prosthesis/bone interface stresses. Therefore, this method can be expected to provide useful information in the preoperative planning of difficult reconstructive cases involving the hip.

Development of Y II Cementless Total Hip System Using a Socket with Three Spikes

The advantage of a surgical procedure using the design of the Y II cementless total hip system using a socket with three spikes (Y II THA), which is applied in our department, is reported. The Y II THA has been developed based on the results of the computer simulation using the rigid body spring model (RBSM), animal experiments, and previous clinical experience. The Y II socket consists of a hemispherical metal socket made of titanium alloy and artificial cartilage made of polyethylene, which is screwed into the metal socket, called a metal back system. The thickness of the artificial cartilage is 9mm. The metal socket has three spikes. One of them has a notched surface and the length is 35 mm. The surface of the remaining two spikes is smooth and 23 mm in length. This socket is inserted at a 35° open angle by using an angle finder without removing the residual cartilage or subchondral bone. The Y II stem is made of titanium alloy and has a collar at the neck. The femoral neck angle is 35° and the length is 178 mm. Several longitudinal grooves are engraved on the smooth surface, called a fluted type. There are three sizes: small, standard, and large. The femoral head, made of cobalt-chromium alloy, is 23 mm in diameter. This is called a modular type. The femoral neck is excised at a 35° angle to the horizontal line with 8 mm of calcar left from the base of the lesser trochanter. Then, the femoral medullary canal is reamed to the minimal necessary extent using a rasp whose size was preoperatively determined by a template. Forty-one joints of 41 patients underwent total hip arthroplasty using the Y II THA and were followed up for more than 3 years. All patients achieved excellent clinical results and stable mechanical durability according to radiographic findings.