Yoshitaka Shinto

Calcium hydroxyapatite ceramic used as a delivery system for antibiotics

Porous blocks of calcium hydroxyapatite ceramic were evaluated as delivery systems for the sustained release of antibiotics. We tested gentamicin sulphate, cefoperazone sodium, and flomoxef sodium in powder form placed in a cylindrical cavity in calcium hydroxyapatite blocks, using in vitro studies of elution and in vivo studies in rats. Gentamicin sulphate gave a maximum concentration within the first week, which gradually decreased but was still effective at 12 weeks, when 70% of the antibiotic had been released. Even at this stage the antibiotic concentration from a 75 mg dose was five times the minimum inhibitory concentration for staphylococci. In the in vivo studies the release of gentamicin sulphate into the normal bone of rats was at similar rates and levels. The bacteriocidal activity of the drugs was not affected by packing into calcium hydroxyapatite ceramic and the blocks were completely biocompatible on histology. This new system overcomes the disadvantages of other drug delivery systems, avoiding thermal damage to the antibiotics and a second operation for the removal of the carrier. Some mechanical strength is provided by the ceramic and healing may be accelerated by bone ingrowth into its micropores.

The use of calcium hydroxyapatite ceramic in bone tumour surgery

We report 60 benign bone tumours treated by resection and curettage followed by the implantation of calcium hydroxyapatite ceramic (CHA). After follow-up of six to 60 months (average 36), no patient had local recurrence of the tumour or any adverse effects from the implants. In almost all cases radiography showed that the CHA was well-incorporated into the host bone, with new bone formation in and around the CHA. Corrective remodelling of deformed bone and normal fracture healing suggested that there was normal bone turnover in the presence of the CHA. Histology of biopsies from seven patients showed bone ingrowth into the pore structure of CHA in the central zone of some defects by one year after implantation. CHA appears to be a useful substitute for bone graft in the treatment of some benign tumours.

Treatment of chronic osteomyelitis using calcium hydroxyapatite ceramic implants impregnated with antibiotic.

Summary.We treated eighteen patients with chronic osteomyelitis by implanting pieces of antibiotic-impregnated calcium hydroxyapatite ceramic into a cavity produced after thorough surgical excision of necrotic tissue. Within three months the infected sites had all healed. During follow-up ranging from 24 to 75 months there was no recurrence of infection. Two of the patients had infected prosthetic joints which were successfully revised. Infection was controlled and incorporation of the ceramic material into host bone was demonstrated radiographically. We recommend the use of porous pieces of calcium hydroxyapatite impregnated with antibiotic as a new system for drug delivery in the treatment of chronic osteomyelitis.Résumé.Les auteurs rapportent le traitement de 18 patients atteints d’ostéomyélite chronique par excision chirurgicale suivie d’implantation de fragments d’hydroxyapatite de calcium imprégnés d’antibiotique. Tous les sites d’infection ont cicatrisé dans un délai de 3 mois. Pendant la période de suivi, allant de 24 à 75 mois, il n’y a pas eu de récidive de l’infection. 2 des patients avaient une infection sur prothèse articulaire qui ont été révisés avec succès. En plus du contrôle de l’infection, il a été constaté radiologiquement une incorporation de l’hydroxyapatite. Les auteurs recommandent donc l’utilisation des ces fragments poreux d’hydroxyapatite de calcium imprégnés d’antibiotique pour le traitement de l’ostéomyélite chronique.

Experimental implant-related osteomyelitis treated by antibiotic-calcium hydroxyapatite ceramic composites

The efficacy of locally implanted antibiotic-calcium hydroxyapatite ceramic composites was investigated for the treatment of experimentally produced, implant-related osteomyelitis in rats. High concentrations of antibiotics were detected at the site of infection and bacteria were eradicated without removal of the metal implants. Parenteral antibiotics and surgical debridement, alone or in combination with antibiotic-impregnated acrylic bone cement, all failed to eradicate the infections.

Neoadjuvant chemotherapy for pediatric osteosarcoma patients

Since the first trial for chemotherapy in children with osteosarcoma in 1977, the survival rate has gradually improved. Currently, more than 60% of all patients are cured, mainly because of the introduction of intensive chemotherapy using doxorubicin, high dose methotrexate, and cisplatin. The increased survival rates have promoted efforts to improve the quality of survival through the use of limb salvage surgery rather than amputation. Improvements in chemotherapeutic efficacy should result in a more favorable outcome and better function of the affected limb. The current study evaluated factors that influence chemotherapy so that a higher survival rate could be obtained.

Alumina ceramic prostheses for bone tumor surgery.

SummaryBetween 1979 and 1990 reconstruction using a ceramic prosthesis with a polycrystal alumina segment and a monocrystal alumina stem was carried out in 65 patients after the resection of malignant or benign aggressive bone tumors. Resection of 18 osteosarcomas, 5 chondrosarcomas, 9 other sarcomas, 10 giant cell tumors, 20 metastatic bone tumors, and 3 other bone tumors was followed by replacement of 17 proximal femurs, 12 distal femurs, 12 proximal tibia, 11 proximal humeri, 3 distal radii, 5 midshafts of the long bone, 2 pelvises, and 3 other parts. Results were rated excellent in 4 cases, good in 43, fair in 13, and poor in 4. In the cases with benignly aggressive or low-grade malignant tumors and those with tumors of the proximal femur, proximal tibia, or midshaft, satisfactory results can be obtained. Four skin ulcers, three dislocations, three loosenings, two infections, and two breaks were noted. Close interfacing between the ceramic prosthesis and the bone was observed radiologically in all cases with cementless fixation except in cases with high-grade malignancies in the knee joint. These results demonstrate that the ceramic prosthesis can be beneficial for the management of patients with benignly aggressive or low-grade malignant bone tumors who have retained adequate muscle strength around the joint even after tumor resection.

Inguinal lymphadenopathy due to metal release from a prosthesis. A case report

We report the case of a 19-year-old man with inguinal lymphadenopathy caused by metallic debris from the loosening of a prosthesis inserted after tumour resection. Large amounts of wear debris may be released from such massive replacements, and surgeons should be aware of the range of possible adverse effects.

Calcium Hydroxyapatite Ceramic: Use in Bone Tumor Surgery

Defects in bone, as a result of surgical treatment for bone tumors, are a frequent occurrence. These defects are usually filled with bone graft for which autogenous bone is used in most cases. It may be difficult, however, to obtain the amount required. Moreover, the wound over the iliac crest, made for obtaining autogenous bone, is frequently more painful than the original operation for which the bone was required. There is thus an obvious need for a synthetic material which can be used in place of a bone graft. Calcium hydroxyapatite ceramic (CHA) is a nontoxic substance, provoking little reaction from tissues, and which has many properties, both chemical and physical, that might make it a suitable alternative to bone grafts. Therefore, CHA may be preferable for filling defects that occur after resection and curettage of benign bone tumors.

Replacement by Ceramic Prostheses for the Treatment of Malignant and Benign Aggressive Bone Tumors

Originally, the investigators of limb-salvage operations were mainly concerned with postoperative function. This objective has been realized not only by the progress of prosthetic design, but by the various efforts intended to minimize the resection area [1–5]. The next concern concentrated on two goals: to extend the yardsticks for the indication of the prosthetic replacement for the growing, younger patients and to improve the design of the prosthesis for long-term application, because most of the patients who undergo this type of operation are relatively young. In addition, the loss of bone stock around the prosthesis after longterm use would make any revision surgery more difficult. Several kinds of extending prostheses and temporary resection-arthrodesis were attempted for attaining the first goal [6–9]. Operations employing prostheses with porous-coated stems and anti-micromotion blades, prostheses with porous-coated segments for bone grafts and cement-fixed stems, long-stem prostheses with allografted segments, and ceramic prostheses were performed for achieving the second objective [10–18]. On the other hand, allograft, reimplantation of affected bone with both extracorporeal and intracorporeal irradiation were also carried out because these bones can be permanently used if they could be revascularized and reconstructed with normal bone tissue [19–22]. These methods have another advantage in that they preserve joint cartilage and the attachment of muscle or ligament because these tissues are more resistant against irradiation. However, these methods bear the problem of a high rate of complications, such as infection, fracture, or necrosis [23].

A Limb-Saving Operation for Cases with Malignant Pelvic Bone Tumors

At present, primary malignant tumors involving the pelvic bone are treated with hemipelvectomy. However, a limb-saving operation should theoretically obtain the same surgical margin in tumor resection as that of a hemipelvectomy (Fig. 1). Based on this functional consideration, limb-saving operations have been performed on selected patients. In this paper, we describe the methods of resection and reconstruction, and the functional results in limb-saving operations of primary malignant pelvic tumors.