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Biomedical subjects

V Ritsilä

Publications and source records attributed to V Ritsilä.

At least 19 recordsLinked to original sources
PubMed2005

A novel bioabsorbable composite membrane of Polyactive 70/30 and bioactive glass number 13--93 in repair of experimental maxillary alveolar cleft defects.

A novel bioabsorbable composite membrane of polyethylene oxide terephthalate and polybutylene terephthalate copolymer (Polyactive 70/30) combined with bioactive glass No. 13--93 was tested in the repair of experimental maxillary alveolar cleft defects. In this pilot study, the possible ability of the membrane to promote bone formation by guided tissue regeneration was investigated. Standard alveolar defects were made bilaterally in the maxilla of 12 growing rabbits and were filled with autogenous bone grafts. The test defect was covered with the composite membrane and the other defect was left uncovered to serve as a control. The follow-up time was 10 weeks. Radiological, histological, and histomorphometric evaluations were performed. Radiologically, no statistically significant differences between test and control defects at 10 weeks were found. Histologically, the membrane enhanced osteogenic activity locally at the membrane-bone interface. Swelling of the membrane was observed. Histomorphometrically, no significant promotion of bone formation by the membrane was observed. The composite membrane was found to be biocompatible and surgically easy to use, but its osteopromotive effect was limited in this experimental cleft model. Further studies are necessary to assess its suitability for reconstructive surgical applications.

Alveolar Process↗
PubMed2004

Primary cartilage lesions of the knee joint in young male adults. Overweight as a predisposing factor. An arthroscopic study.

BACKGROUND AND AIMS: This study was undertaken to evaluate the relationship between overweight and severity of arthroscopically confirmed primary cartilage lesions of the knee. MATERIAL AND METHODS: The hospital records of 88 young male adults (98 knees), who underwent arthroscopy of the knee and were diagnosed of primary cartilage lesion during 1997-98, were reviewed. The depth of the lesions was graded according to Beguin and Locker classification. RESULTS: 73.5 % of the lesions were patellar and 12.0 % in the medial condyle of the femur. 74.5 % of the patients had superficial (grade I-II) and 25.5 % deep (grade III-IV) lesions. Patients with deep lesions had a significantly higher body mass index (BMI 25.3 vs. 22.9, p < 0.001) and they were older (20.8 vs. 19.7 years, p = 0.023) than other patients. Similarly, patients with overweight (BMI > or = 25.0) had significantly more often deep lesions than other patients (50 % vs. 10.4 %, p < 0.001). CONCLUSIONS: These results suggest, that overweight may predispose young patients to more severe cartilage lesions independent of other etiologic factors, and support the hypothesis of the cumulative effect of overweight on cartilage injuries during early adult life.

Adult↗
PubMed2000

Experimental anterior spine fusion using bovine bone morphogenetic protein: a study in rabbits.

We developed an experimental model to study the merit of bovine bone morphogenic protein (bBMP) injection into the intervertebral disc to induce anterior interbody fusion. A total of 24 rabbits, divided into three groups of 8 animals each, were used. One hundred and fifty microg of partially purified bBMP was employed in the first group and 10 microg bBMP in the second group. In the control group, a sham operation was performed. The animals were followed radiographically at weekly intervals and animals were killed 3, 6, and 12 weeks postoperatively. After sacrifice, a mechanical and histologic evaluation of fusion was performed. Results of radiographic and histologic evaluation showed bone formation, which had resulted in the bridging of adjacent endplates, in the 150-microg group. In the 10-microg group, new bone formation was less extensive. In the control group, intradiscal bone formation was seen in only 1 animal. Range of motion measurements on flexion/extension films showed significantly decreased motion in segments that were fused with 150-microg of BMP. This study demonstrated the utility of an experimental model which allowed investigation of how anterior spine fusion may be further studied. Intradiscal injection of BMP could ultimately play a role in the development of minimally invasive techniques for anterior spinal fusion.

Animals↗
PubMed1993

Effects of distraction and compression on proliferation of growth plate chondrocytes. A study in rabbits.

An external fixation device was applied across the distal femoral physis in 30 rabbits, and distraction or compression was performed for 3-21 days; either no operation or a sham-operation was performed on the contralateral side. Proliferating cells were labeled with 5-bromo-2'-deoxyuridine, a thymidine analogue, and subsequently localized in decalcified histologic sections using a specific monoclonal antibody. The height of the proliferative and hypertrophic zones was increased after distraction; additionally, fracture-separation through the hypertrophic zone or at the junction of the physis and metaphysis was seen in 13 of the 15 specimens. Labeled cells were encountered only in the proliferative zone in all specimens except after early distraction, where labeled chondrocytes were seen close to the separation gap in the hypertrophic zone, too. Distraction had no effect on the number of labeled cells. A reduction in the height of the proliferative and hypertrophic zones occurred after compression, and the number of proliferating chondrocytes decreased.

Animals↗
PubMed1991

Scoliosis in growing rabbits induced with an extension splint.

An external splint was applied to 49, 6-week-old rabbits to induce lordosis in the thoracolumbar junction. The splint was retained for 8 weeks, and the animals were killed after 6 months. Scoliosis developed in 23 rabbits during the splinting period. The deformity occurred about the thoracolumbar junction, and was more frequent in rabbits whose lordosis was sustained when the splint was removed after 8 weeks. The results support the view that sagittal changes are primarily or secondarily involved in the pathomechanics of scoliosis.

Animals↗
PubMed1990

Distraction effects on the physis in rabbits.

Gradual physeal distraction by external fixation was performed on the distal femur in 19 growing rabbits. The rate of distraction was 0.5-1 mm once daily. Distraction was continued for 1-21 days until killing. Lengthening of the femur and latitudinal growth of the distraction area were measured in radiographs. Morphologic changes in the physes were studied in histologic preparations. The length gained by distraction was maximally 5 mm. Latitudinal overgrowth was noted in specimens distracted for more than 13 days. Hyperplasia of the hypertrophic chondrocyte zone was seen after 1 day of distraction. Separation of the epiphysis from the metaphysis, mostly through the hypertrophic zone, occurred in 11 specimens. Both hyperplasia and separation were often seen in the same physis. In the separation gap, early signs of bone formation into a collagen frame were seen from the 7th day on. An accessory physis, located in the metaphysis and apparently growing interstitially, was noted in 1 specimen.

Animals↗
PubMed1984

Experimentally produced growth disturbance of the acetabulum in young rabbits.

The primary aim of this study was to clarify the influence of operations of the acetabular roof on the development of the hip joint in growing rabbits. The second objective was to discover if age had any role in the development of eventual acetabular growth disturbance. The animals were 3 and 8 weeks old at the time of the operation. A wedge-resection was performed on the acetabular roof through an extra-articular approach. In the control series only the soft tissues were operated, and the bony-cartilaginous roof was left intact. The growth of the hips was followed radiographically. In the rabbits operated at the age of 3 weeks acetabular dysplasia developed within a few weeks, associated with subluxation or luxation of the femoral head combined with other secondary changes of the joint. In the rabbits operated at the age of 8 weeks the dysplastic changes of the acetabulum were lesser or no abnormalities could be seen. In the control group the growth of the hip was normal.

Acetabulum↗
PubMed1982

Chondrogenesis in repair of articular cartilage defects by free periosteal grafts in rabbits.

The origin of the cartilaginous tissue in articular defects after periosteal grafting was studied histologically in 6-month-old rabbits. The grafts were taken from the tibia and transplanted to artificial defects in the femoral articular cartilage. An isolating Nuclepore filter, hindering the penetration of cells, was placed between the graft and the cancellous bone, in order to trace the origin of the proliferating cells. The histological results revealed that the cartilage tissue which proliferated in the defect originated from the periosteal graft and not from the subchondral bone. The effect of the depth of the defect was studied by making a superficial and deep part in the defect. Cartilage tissue was found in both parts of the defect, though there was less in the more superficial defect.

Animals↗
PubMed1982

Effects of joint motion on the repair of articular cartilage with free periosteal grafts.

The effects of joint motion on the chondrogenic potential of free autogenous periosteal grafts were studied histologically in 6-month-old rabbits. The grafts were taken from the tibia and transplanted to artificial defects of the femoral articular cartilage. The joint was postoperatively first immobilized and then remobilized for various periods. The results revealed that immobilization for 3 weeks had an inhibitor effect on the chondrogenesis, which was even more pronounced after 6 weeks of immobilization. After remobilization the chondrogenesis partially recovered. This recovery of chondrogenesis was more pronounced after 3 weeks' immobilization than after 6 weeks' immobilization. However, degenerative changes were observed in both series.

Animals↗
PubMed1981

Treatment of lumbar lytic spondylolisthesis using osteoperiosteal transplants in young patients.

A series of 40 young patients with lumbar spondylolisthesis is presented. The patients were treated surgically using osteoperiosteal transplants as the fusion material. In 29 patients, the fusion was posterior and in 11 patients posterolateral. The loose posterior element was removed in eight patients in connection with fusion. The degree of slipping on admission was less than 30% in 18 patients (45%), 30 to 50% in 5 patients (12.5%), and more than half of the olisthetic vertebral body in 17 patients (42.5%). A good clinical result was obtained in 24 patients (60%), satisfactory in 11 (27.5%), and poor in 5 (12.5%). Solid union was obtained in 29 patients (72.5%), nonunion in 7 cases (17.5%), and in 4 patients (10%) the union was considered uncertain. One patient was reoperated on. The best results were obtained using posterior fusion, while the rate of nonunion was higher in the posterolateral group. The periosteum was taken from the anteromedial aspect of the tibia using a sharp chisel. The method gives clinical and radiological results comparable with those obtained using bone transplants.

Adolescent↗
PubMed1981

Differentiation of the osteochondrogenic cells of the periosteum in chondrotrophic environment.

The behaviour of the cells in free periosteal graft was studied in growing rabbits in three chondrotrophic recipient milieus: costal cartilage, ear cartilage and synovial fluid of the knee joint. The periosteal grafts first formed cartilage, which was then quite rapidly transformed into bone on the costal cartilage, quite slowly and in smaller amounts in the ear cartilage, whereas no bone was found in the cartilaginous loose bodies formed in the knee joint. In bone formation vascularization plays a major role, but other factors are also involved.

Animals↗
PubMed1980

The effect of the thickness of the cortical bone on bone formation by osteoperiosteal grafts. A comparative study employing routine histological stains and triple fluorochrome labelling.

The bone-forming capacity of free periosteum was compared with that of 100 micrometers thick osteoperiosteum and periosteum with full thickness cortex taken from the tibia of 6-week-old rabbits. Altogether 78 rabbits were operated on. The results revealed that the osteogenic capacity of free periosteum and 100 micrometers thick osteoperiosteum was about the same, and that osteoperiosteum with full thickness cortex was inferior in this regard.

Animals↗
PubMed1979

Healing of membranous and long bone defects. An experimental study in growing rabbits.

Different isolation models have been used for qualitative and quantitative studies on the individual roles of periosteum, cortical bone, endosteum and bone marrow in the repair of long bone defects. Corresponding skull defects were studied to evaluate also the dural osteogenetic capacity. A total of 53 operations were performed on the tibia and skull of 33 growing rabbits. The animals were killed 10-12 weeks after surgery. Ordinary rough histological methods were used for studying bone formation, and quantitative estimates were made using serial sections. The cortex, endosteum and bone marrow were demonstrated to play a minor part in the healing of tibial defects. Periosteum, on the other hand, had the most potent healing capacity. Calvarial periosteum, however, was found to be less bone producing and in that respect not to be superior to the dura. For a complete bony restoration combined periosteal and dural bone formation is necessary, also regarding the structural normalization.

Animals↗
PubMed1979

The osteogenic capacity of free periosteal and osteoperiosteal grafts. A comparative study in growing rabbits.

The behaviour of free periosteal and 200 micron thick osteoperiosteal grafts was studied histologically in 40 six-week-old rabbits. The grafts were taken from the tibia and fixed on either side of the same lumbar vertebra between the spinous and mamillary processes. The free stripped periosteum had better osteogenic activity than the 200 micron thick osteoperiosteum. The new bone was formed by the osteogenic cells of the cambium layer in both types of graft.

Age Factors↗
PubMed1978

Growth potential of cranial suture bone autografts. I. An experimental macrosopic investigation in young rabbits.

On 25 rabbit sucklings a coronal suture-bone graft was transplanted into an experimental unilateral premaxillo-maxillary bone and stuture defect. 21 animals survived the experimental period and were sacrificed fullgrown (6 months). The graft was found to be well incorporated into the recipient site in all cases, its structure being remodelled to a striking similarity with the unoperated side and the suture was still visible. Photographic measurement of the snout deviation revealed that the longitudinal growth of the grafted suture approximately followed the general growth of the facial skeleton. This indicates an up to 3-fold increase of the growth in comparison to its original cranial growth site.

Animals↗
PubMed1978

Growth potential of cranial suture bone autograft. II. An experimental microscopic investigation in young rabbits.

On rabbit sucklings a coronal suture-bone graft, covered by periosteum and dura, was transplanted into an experimental unilateral premaxillo-maxillary bone and suture defect. In 21 animals microscopical analysis was carried out using triple fluorochrome vital labelling over a period from the 3rd to the 36th postoperative day. In another 7 animals conventional histological methods were used. The grafts were readily incorporated and during the second postoperative week longitudinal sutural growth was fully restored as compared to the unoperated control side and growth far exceeded that of the original coronal suture.

Animals↗
PubMed1978

Osteogenic capacity of periosteal grafts. A qualitative and quantitative study of membranous and tubular bone periosteum in young rabbits.

A standardized model, permitting only periosteal bone formation, has been applied for qualitative and quantitative studies on the osteogeneses from periosteal grafts. The periosteum from the tibia was grafted to the skull and vice versa. The investigation also included the study of periosteal bone formation combined with other osteogenic factors. A total of 78 operations were performed on the tibias and skulls of 43 growing rabbits. For qualitative studies ordinary histological methods were used. Tibial periosteal grafts to skull defects started bone formation already after 2 weeks and, via a very small amount of woven bone, compact bone and bone marrow was formed after 8-10 weeks. Combined epidural and subperiosteal bone formation gave a calvarial bone. Skull periosteal grafts to tibial defects started bone formation somewhat later, but, after more woven bone as an intermediate stage, the defect had healed with thick compact bone and bone marrow after about the same period. For quantitative studies the newly formed periosteal bone was removed, dry-weighted and ashed. The ashes were dissolved in HCl for spectrophotometric determination of total Ca content, which was used as a quantitative measure of bone amount. Tibial periosteum grafted to a calvarial defect halved its bone forming capacity but compared to the in situ skull periosteal potential, the capacity was tripled. This meant that the defect was completely healed. Calvarial periosteum was much less potent than was the tibial periosteum, when both were grafted to skull defects. However, when transplanted to a long bone defect the former increased its bone forming capacity 5 times compared to its original one as an in situ flap. Environmental functional demands seem to influence the type of bone formation and the final structure of the new bone. On the other hand, there are differences between long and membranous bone periosteum regarding the amount of bone formed.

Animals↗