Effect of diffusion chamber pore size on differentiation and proliferation of periosteal cells. An experimental study

The influence of the pore size of Nucleopore diffusion-chamber filters on the rate of proliferation and differentiation of periosteal cells in muscle was studied in 44 growing rabbits. Periosteal grafts were placed in chambers (16-19 in each experimental group) sealed with filters with a pore size of 0.4, 0.6, 0.8, 1.0, or 2.0 micron. Each chamber was implanted into the paraspinal muscle of the rabbit, where it remained for 16 weeks. The osteochondrogenic activity of the graft grew linearly when the pore size increased from 0.4 to 1.0 micron. In the chambers with a pore size of 2.0 micron, both bone and cartilage were found in only one chamber. Bone and cartilage were not found outside any of the chambers. The present results showed that the pore size of the filters significantly affected the ability of the periosteal graft to form bone and cartilage.     

Repair of maxillary alveolar cleft defects with two different bioabsorbable implants: an experimental study in growing rabbits

Two different bioabsorbable implants and their ability to promote bone formation in repair of experimental maxillary defects were investigated. A poly-L/D-lactide mesh and a two-layer composite membrane consisting of a film made of a copolymer of L-lactic acid and )-caprolactone combined with the polylactide mesh were used as implants. A standard alveolar defect was made bilaterally in the maxilla and filled with autogenous bone grafts in 30 growing rabbits. Follow-up was 10 weeks. Three experimental groups were formed: (1) defect covered with polylactide mesh versus control defect without implant, (2) defect covered with composite membrane versus control defect, and (3) defect covered with membrane on one side and with mesh on the other. Radiological, histological and histomorphometric evaluations were performed. In histomorphometric measurements, a significantly larger quantity of bone was observed in the composite membrane-covered defects compared with the polylactide mesh-covered and the control defects. Osteogenic activity was also highest in the membrane-covered defects. The bioabsorbable composite membrane appears to promote healing of experimental maxillary alveolar defects in accordance with the principle of guided tissue regeneration. The polylactide mesh alone was less potent in promoting healing of the defect, although an enhancing effect on osteogenic activity was observed.     

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.     

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.     

Spinal fusion with free periosteal grafts and its effect on vertebral growth in yound rabbits.

The effect of early fusion on growth of the spine has been studied in rabbits. Free periosteal grafts from the tibia were transplanted either posteriorly between the spinous and articular processes or postero-laterally between the articular and transverse processes. Sound bony fusion was achieved in both the thoracic and the lumbar spine. Spinal fusion caused local narrowing and wedging of the intervertebral spaces, followed by retardation of growth and wedging of the vertebrae. A progressive structural scoliosis developed after unilateral postero-lateral fusion and a lordosis developed after posterior fusion.     

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 μg of partially purified bBMP was employed in the first group and 10 μg 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-μg group. In the 10-μg 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-μg 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. Received for publication on Jan. 6, 1999; accepted on Aug. 18, 1999     

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.