Small PMMA beads improve gentamicin release

The in vivo release of gentamicin base from conventional polymethyl methacrylate 7-mm beads was compared with that from the recently introduced 3 x 5-mm minibeads. The release in 14 days from minibeads was 93 percent of their gentamicin content, while the large beads released an average of 24 percent. The volume of the minibeads is one fifth of that of the large beads. Owing to the improved release combined with the smaller size, total release from minibeads in a cavity may be some seven times that from large beads. When in smaller cavities a strong bactericidal effect is desired, minibeads are to be preferred to large beads.     

Small PMMA beads improve gentamicin release

The in vivo release of gentamicin base from conventional polymethyl methacrylate 7-mm beads was compared with that from the recently introduced 3 × 5-mm minibeads. The release in 14 days from minibeads was 93 percent of their gentamicin content, while the large beads released an average of 24 percent. The volume of the minibeads is one fifth of that of the large beads, Owing to the improved release combined with the smaller size, total release from minibeads in a cavity may be some seven times that from large beads. When in smaller cavities a strong bactericidal effect is desired, minibeads are to be preferred to large beads.     

Experimental microsurgery in rats (author's transl)]

Experimental microsurgical techniques using a magnifying glass and surgical microscope enable nearly all abdominal operations and organ transplantations to be performed in rats. Vascular and prosthetic segment implantations, portocaval anastomoses, heterotopic heart-, kidney-, spleen-, pancreas-, and liver transplantations some with superselective organangiography, are excellently demonstrated. Continuing research in microsurgery has considerably expanded experimental surgery and given new impulse to clinical surgery.     

Experimental studies of skull fracture in the temporal region (author's transl)]

These experimental studies of skull fractures in the temporal region were carried out in co-operation the Faculty of Engineering and the Department of Neurosurgery of Tokyo University. 15 dry human skulls were statically compressed in the bitemporal direction. The results of our experiments are as follows: 1) The forces necessary to produce the first fracture (seperations of the parietotemporal suture) are between 135 kg and 385 kg. (average; 258 kg) 2) The forces necessary to produce the second fractures (true fractures) are between 195 kg and 550 kg. (average; 356.3 kg) 3) The decreases of the inner diameters of skulls from pre-examination to the first fracture are between 0.65 mm and 1.85 mm. 4) The decreases of the inner diameters of skulls from pre-examination to the second fracture are between 1.56 mm and 4.5 mm. 5) The forces necessary to reduce the inner diameters of skulls by 1 milimeter are between 85 kg/mm and 380 kg/mm. (average; 221 kg/mm) The forces necessary to produce a fracture in the temporal region are much less than the forces necessary to do so in the frontal region. In deforming the skull, it is necessary to apply much greater force to the frontal region than it is to the temporal region. The relation between the skull's age and the minimal force to produce the skull fracture is not clear from the results of these experiments. The weights of the skulls were directly related to the minimal force necessary to produce skull fractures. Breaks in the inner table preceded those of the outer table when linear fractures occurred over the compressed area. when depressed fractures formed in the same area, the outer table was broken before the inner table. When the linear fractures formed far from the same area, the outer table was broken before the inner table. From our investigations on sports injuries, those players who died after being hit by golf balls or baseballs showed the same clinical courses as in typical extradural hematoma. Plain X-ray examinations of those fataly injured players did not reveal any skull fractures. Plain X-ray examinations of fractured skulls often failed to reveal the lesion unless the bone fracture was widely separated. On the basis of the above results, it would appear that routine skull films using either anterior-posterior or lateral projections are inadequate for the diagnosis of skull fractures. We have had good results in the examination of skull fracture by using the stereo X-ray method.     

Experimental and clinical studies on the Jikei total knee prosthesis (author's transl)]

Total knee prostheses for a dog were developed and were inserted into knee joints of seven adult dogs to study the mobility of the artificial joint, the degree of fixation to bone and the durability of the prosthesis, to examine the reactions in the surrounding tissues and the internal organs in the JIKEI total knee prosthesis in clinical use. As a result of surgery, it was proved that the length in the hinged part of the prosthesis needed to be seventy percent of the length of the excised area of the joint to gain good mobility and supportability of the knee joint after surgery. As a result of findings based on necropsy, wear at the hinged part of the prosthesis was mild and debris caused in wear was not harmful for the living body if breakage does not occur there. Histopathological findings revealed that collagenous fibrous tissue with new bone formation was observed on the inner wall of the bone around the stem of the prosthesis four months after surgery. Then it was proved that the fixation of the prosthesis to the bone was sufficient. Therefore the author would like to mention that bone cement is not necessary for the fixation between bone and prostheses. The JIKEI total knee prosthesis (universal type) based on the results of these experimental studies has been developed and was used to the clinical cases. The clinical results until four years after surgery have been most satisfactory with loss of pain, good supportability and movement of joints in almost all of the cases.     

Comparative studies of radioisotope uroflowmetry (author's transl)]

Radioisotope uroflowmetry allows continuous recording of urinary stream with determination of maximum and mean urine flow rate, duration of voiding and residual urine without urethral catheterisation. By the aid of twenty simulated tests and nine examinated patients the precision of this method was investigated by comparing our results with the findings of simultaneously recorded mictiographic measurement. The flow curves and the maximum flow rate show a high correlation.     

Treatment of chronic post-traumatic infections of the bone and soft tissue with gentamycin PMMA beads (PMMA = polymethylmethacrylate) (author's transl)

Temporary implantation of Gentamycin PMMA beads and chains provides a most effective local antibiotic therapy as supplementary and consecutive treatment after surgical procedures executed in bone and soft tissue infections. Gentamycin beads and chains are used as an alternative to irrigation-suction drainage. From 1977 to 1979 70 patients were treated for chronic post-traumatic osteomyelitis and infection of the soft tissue. The chronic bone infections subsided completely in 90% of the patients, but 8.3% re-infections were observed within 3 to 24 months after termination of treatment. In 18 patients with gunshot wounds 66.6% of the patients got primary healing and 33.4% secondary healing.