A polyethylene-high proportion hydroxyapatite implant and its investigation in vivo.

An implant from hydroxyapatite and polyethylene (HA+PE) composite was investigated for the usability in large bone defects. With this aim, the implants were manufactured in blocks by hot compacting the mixture of 80% HA and 20% PE weight ratio. Powders were machined in a lathe in the dimensions of diaphysis of the radius of the mongrel dogs. Then a defect, 1.5 cm in length, was made in the diaphysis of the radius with an operation performed under general anaesthesia in 16 healthy mongrel dogs. The defects were filled with implant as a block. The dogs were observed radiologically in 15-day intervals and examined clinically in certain intervals. The bone samples were taken out from four dogs for the histopatological examinations at the end of the 2nd, 4th, 6th and 12th months, respectively. Clinical examinations indicated the occurrence of slight lameness in all cases at the first month of experiment, but lameness completely disappeared in a further examination. Progressive resorption and new bone formation began in the implants from the first month, but complete resorption was not observed in any case at the end of 12-month period. SEM and optical microscope examinations revealed fibroblast cell with its clear cytoplasmic extensions and osteoblast cells in endosteum in the inner region. Bone formation increasing and extending to the pores of implant in time and blood vessels with lamellar structure and Haversian system were observed. As a result, it was indicated that HA+PE composite implants could be applied with confidence and are useful in treatment of large bone defects in long bone of dogs.

Comparative macroanatomical study of the neurocranium in some carnivora.

This study was carried out to investigate the specific anatomical features of the neurocranium of the skull of the dog, cat, badger, marten and otter. Twenty-five animals (five from each species) were used without sexual distinction. The neurocranium consists of os occipitale, os sphenoidale, os pterygoideum, os ethmoidale, vomer, os temporale, os parietale and os frontale. The processus paracondylaris is projected ventrally in the cat, dog, marten and badger, and caudally in the otter. Two foramina were found laterally on each side of the protuberantia occipitalis externa in the otter, and one foramen was found near the protuberantia occipitalis externa in the badger. Foramen was not seen in other species. Paired ossa parietalia joined each other at the midline, forming the sutura sagittalis in the badger, dog, otter and cat while it was separated by the linea temporalis in the marten. The os frontale was small in otters, narrow and long in martens, and quite wide in cats and dogs. The bulla tympanica was rounded in the marten, dog, cat and badger, dorsoventral compressed in otter, and it was very large in all species examined. These observations represented interspecies differences in the neurocranium of marten, otter, badger, cat and dog.