In patients with malignant tumors in the region of the shoulder, radical resection can avoid amputation in most instances. To improve the function of the arm, endoprosthetic replacement of the defect is desirable. A three-component endoprosthesis made of a bioceramic material (aluminium oxide) was designed, implanted without bone cement. Fast anchorage to bone is achieved by using a conical sleeve, fixed upon the previously conically reamed humerus shaft. A stable primary fit is always feasible. Subsequent bone in growth into grooves inside the conical sleeve provides a permanent anchorage of the endoprosthesis. The authors experiences are based on implantations of 38 endoprostheses. The original diseases were primary malignant bone tumors in 19 patients, one case of "solitary" plasmocytoma and metastases into the proximal humerus in 16 patients. In two women, resection was made because of posttraumatic subcapital humeral pseudarthrosis. The follow-up study includes only those 27 cases operated on at least one year ago. 12 of the 14 patients with primary tumors have been surviving for 12-55 months (range 27.4) without signs of metastases or recurrent disease. Seven patients with metastases died of their original diseases after 7.7 months on the average. Owing to extensive resection of the shoulder musculature the mobility in the shoulder joint is considerably reduced. All the patients have good movement of the elbow joint and free function of the hand.
This paper describes the design principles of a new endoprosthesis made of dense aluminum oxide (A12O3) and implanted without bone cement. Mechanical tests and animal experiments have proved the sufficient mechanical strength of the bone-prosthesis connection as well as the biocompatibility of the material. So far, 12 tumor patients selected according to strict indication criteria have been operated on. Both the clinical-radiologic and the first histological findings available are encouraging. Special reference is made to the first fully ceramic total hip joint endoprostheses implanted in a human without bone cement.
Various implants have been developed for the upper and lower extremities and the spine. In order to establish whether endoprostheses made of Al2O3 will show the same good biocompatibility in humans as it has in experiments with animals, endoprostheses implantations were performed in 4 patients: 2 upper arms, 1 radius, 1 vertebra body. The implants were exposed to various loads. The biomechanical conditions were considered in the construction. The results reveal that the knowledge of material properties and prior calculations make possible the development of satisfactory endoprostheses. X-ray examinations confirm these deductions. Good functionality was achieved in vivo with all implants. They were all mechanially anchored, no bone cement was used. Thus the biocompatibility of the material was not limited. A histological examination is made of one implant. The macroscopic examination showed a stable fit and no pathological reactions, X-rays revealed that the bone remained in good contact with the implant. The longest observation period was over 1 1/4 years. Present observations show that the use of Al2O3 implants, without the use of additional materials (bone cement), results in a tight fit of the implants.
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