Search PubMed⌕ Search

Biomedical subjects

K Vihtonen

Publications and source records attributed to K Vihtonen.

34 records · Page 2Linked to original sources
PubMed1990

Healing of physeal fracture after fixation with biodegradable self-reinforced polyglycolic acid pins. An experimental study on growing rabbits.

Physeal fractures occur at a frequency of 15% of all long bone fractures in children. Undisturbed continued bone growth is the main goal of the treatment of these fractures. After the operative reduction and fixation, whenever needed, a second operation for the removal of the pins is inevitable. The purpose of this study was to develop a biodegradable fixation device for transphyseal fracture fixation, abolishing the need of removal operation. Epiphyseal separation of the distal femoral physis was made on the right side in 18 five-week-old rabbits. The fixation of the physeal fracture was made with two self-reinforced polyglycolic acid (SR-PGA) pins 1mm in nominal diameter and 25mm in length. The follow-up times were 3, 6, 12, 24, and 28 weeks. The distal femoral growth-plate of both femurs was analyzed by radiographic, microradiographic, oxytetracycline-fluorescence, histological and histomorphometric studies. Histomorphometric studies showed normal features of growth. Two growth-plate-penetrating transcondylar SR-PGA implants, of 1mm in diameter, provided sufficient stability for the fixation of a distal femoral physeal fracture in a growing rabbit, and did not cause any growth disturbance.

Animals↗
PubMed1989

The effect of a penetrating biodegradable implant on the growth plate. An experimental study on growing rabbits with special reference to polydioxanone.

This study examined the fate of a biodegradable polydioxanone (PDS) implant in growing bone in rabbits. In 20 immature rabbits, a PDS rod 2.0 mm in diameter and 25 mm in length was driven into a drill hole of equal bore in the intercondylar portion of the right femur across the central portion of the growth plate. In another 25 immature rabbits, a PDS rod 3.2 mm in diameter and 25 mm in length was driven into a corresponding drill hole using the same technique. The follow-up intervals were three, six, 12, 24, and 36 weeks. The distal femoral growth plates of both femora were analyzed by roentgenographic, microroentgenographic, oxytetracycline-fluorescence, histologic, and histomorphometric studies. Histomorphometric studies showed clear changes at the site of injury and appeared to be an excellent means of providing an exact numerical description of the different cellular areas of the growth plate in experimental studies. A transphyseal PDS implant 2.0 mm in diameter did not cause any permanent growth disturbance of the femur in a growing rabbit. An implant 3.2 mm in diameter caused a growth disturbance similar to a drill hole of equal bore.

Animals↗
PubMed1989

Medetomidine--ketamine--diazepam anesthesia in the rabbit.

Orthopaedic operations were performed in 340 rabbits when developing biodegradable rods for the fixation of fractures. The rabbits were anaesthesized by injecting medetomidine combined with ketamine and diazepam (MKD) subcutaneously. The mortality due to the anaesthesia was zero. Arterial blood gas analyses showed a moderate decrease in the haemoglobin oxygen saturation and compensated respiratory acidosis, which was well tolerated by the animals. It is concluded that MKD anaesthesia is well suited for orthopaedic operations in the rabbit.

Adrenergic alpha-Agonists↗
PubMed1989

Ankle fractures treated using biodegradable internal fixation.

In order to reduce the resources needed for the removal of metallic fixation devices in fracture treatment, absorbable implants of biodegradable synthetic polymers were developed using self-reinforced lactide-glycolide copolymer and polyglycolide. In a prospective study 102 patients with displaced unimalleolar or bimalleolar fractures of the ankle were managed using internal fixation devices consisting of cylindrical biodegradable implants 3.2 or 4.5 mm in diameter and 50 or 70 mm in length. After open reduction of the fracture a channel was drilled from the tip of the malleolus into the cancellous bone through the fracture surfaces. A biodegradable rod of the same diameter was then tapped into the drill channel to fix the fracture. Postoperatively, the ankle was immobilized by a plaster cast for six weeks. An anatomic initial reduction was achieved in 93 patients (91%). A slight secondary displacement occurred in four patients. In six patients a sinus formation yielding remnants of the degrading implant was seen two to four months after the operation. This minor complication did not influence the union of the fracture or functional recovery. At the one-year follow-up examination there was no change in the ability to participate in sports and other physical activities in 89 patients (87%). The biodegradable fixation method is now the routine approach of the department in treating displaced unimalleolar and bimalleolar ankle fractures. New clinical applications for the implants are under trial.

Adolescent↗
PubMed1988

The effect of trauma to the lower femoral epiphyseal plate. An experimental study in rabbits.

Forty-four rabbits were operated on when five weeks old; in one group a 2 mm drill-hole was made in the intercondylar portion of the right femur across the central portion of the growth plate up to the diaphysis, while in the other group a similar drill-hole of 3.2 mm was made. At 3, 6, 12 and 24 weeks after operation, specimens from the growth plates of both femora were analysed using radiographic, microradiographic, histological and histomorphometric techniques. It was found that destruction of 7% of the cross-sectional area of the growth plate caused permanent growth disturbance and shortening of the femur.

Animals↗
PubMed1988

Fixation of rabbit osteotomies with biodegradable polyglycolic acid thread.

In 68 rabbits, osteotomies of the femoral medial condyle were fixed with either liquid n-buty-2-cyanoacrylate, bone cement and biodegradable polyglycolic acid (PGA) thread, or PGA thread only. Follow-up times were 1, 3, 6, 12, 24, and 48 weeks. Macroscopic, radiographic, histologic, microradiographic, and oxytetracycline labeling studies were performed. Microscopically, the medial condyles fixed with the combined materials healed in 8 of 34 rabbits and with PGA threads in 22 of 34.

Animals↗
PubMed1987

Biodegradable internal fixation for malleolar fractures. A prospective randomised trial.

Fifty-six patients with displaced malleolar fractures had open reduction and fixation of the fracture fragments using, by random selection, either biodegradable implants or metal AO plates and screws. The cylindrical biodegradable implants were made of polylactide-glycolide copolymer (polyglactin 910). The complications, radiographic results and functional recovery were studied prospectively. After follow-up of at least one year, no significant differences emerged in the complication rate or in the results of treatment between the two methods of fixation. Because of the advantage of avoiding the need to remove metal fixation after union, we now use biodegradable internal fixation routinely to treat displaced malleolar fractures.

Adult↗
PubMed1987

Fixation of experimental osteotomy of the distal femur with biodegradable thread in rabbits.

A distal femoral osteotomy on 24 rabbits was fixed with biodegradable polyglycolic acid (PGA) thread pulled through drill holes made on both sides of the osteotomy. Follow-up times were one, three, six, 12 and 24 weeks. The distal part of each femur was removed, fixed in alcohol, embedded in methylmethacrylate, sawed to 80 microns thick for oxytetracycline (OTC)-labeling studies and microradiography, and sectioned at 5 microns for histologic studies. As judged by histologic microradiographic, and OTC-labeling studies, 19 of 24 osteotomies were healing normally; after six weeks of follow-up examination, union of 11 of 14 osteotomies was observed on radiographs. On the basis of the present study, PGA threads may be promising for the fixation of osteotomies of the metaphyseal cancellous bone in rabbits.

Animals↗
PubMed1986

Fixation of experimental osteotomies of the distal femur in rabbits with bone cement and cyanoacrylate.

A distal femoral osteotomy was fixed with liquid cyanoacrylate and bone cement in 25 rabbits. Follow-up was done at 1, 3, 6, 12, and 24 weeks. The distal portion of each femur was removed, fixed in alcohol, embedded in methylmethacrylate, sawed to 80 micron thickness for OTC-fluorescence study and microradiography, and cut to 5-micron sections for histological analysis. Radiological and careful microscopic (OTC labeling, microradiographic, and histological) studies showed healing of the osteotomies during the first 6 weeks after operation. However, at 12 and 24 weeks' follow-up only four of ten osteotomies had healed. According to these observations it is obvious that fixation of an osteotomy of the cancellous bone with bone cement and cyanoacrylate does not provide sufficient stability for successful healing.

Adhesiveness↗
PubMed1986

Fixation of experimental osteotomies of the distal femur of rabbits with biodegradable material.

Osteotomies of the distal femur in 19 rabbits were operatively fixed with totally biodegradable implants. Radiographic, histological, microradiographic, and oxytetracycline-labeling studies showing healing of the osteotomy within 6 weeks. The fixation proved stable sufficiently during healing of the osteotomized bone. The osteotomies united without delay and malalignment did not occur, although no external support was used and the rabbits were allowed to walk freely after the operation. Successful use of the biodegradable fixation developed in the present study was reported recently for the treatment of fractures of the ankle.

Animals↗
PubMed1986

Biodegradable fixation of rabbit osteotomies.

Osteotomies of the tibial diaphysis were operatively fixed with biodegradable implants in 44 rabbits. Polyglycolic acid (PGA)/polylactic acid (PLA) copolymer implants reinforced with 7 per cent carbon fibre and overlaid with gold were used in 24 rabbits. Poly-beta-hydroxy butyric acid (PHBA) with carbon fibre reinforcement and gold surfacing were used in 20 rabbits. No external support was used. Unsatisfactory results were achieved with the PGA/PLA copolymer implants. Better results were achieved in 15 out of 20 rabbits whose osteotomies were fixed with carbon fibre-reinforced PHBA implants.

Animals↗
PubMed1985

Biodegradable implants in fracture fixation: early results of treatment of fractures of the ankle.

Biodegradable polylactide-glycolide copolymer implants for fracture fixation were developed and tested in rabbits. In a prospective clinical study 44 patients with a displaced fracture of the ankle were randomly allocated to two groups; one was treated with conventional metallic implants and the other with the biodegradable implants. There were no differences between the two groups in the early results, but the biodegradable fixation method is advantageous because the removal procedure associated with metallic implants is avoided.

Adult↗
PubMedDate not supplied

The effect of a penetrating biodegradable implant on the epiphyseal plate: an experimental study on growing rabbits with special regard to polyglactin 910.

A polyglactin 910 rod 3.2 mm in diameter and 25 mm in length was driven in a drill hole in the intercondylar portion of the right femur across the central portion of the growth plate in 20 5-week-old rabbits. The follow-up times were 3, 6, 12, and 24 weeks. The distal femoral growth plates of both femurs were analyzed by radiographic, microradiographic, and oxytetracycline fluorescence, histological, and histomorphometric studies. Histomorphometric studies showed clear changes at injury site and appeared to be an excellent means of exact numerical description of the different cellular areas of the growth plate. Six weeks after implantation, a polyglactin 910 implant resulted in a growth disturbance similar to that of a drill hole of equal bore.

Animals↗