We analyzed osseous reactions in the rabbit femoral condyle to coralline hydroxyapatite bone substitutes of various pore sizes by radiology and histology. The results were compared to bone repair of empty cavities and to integration of allografts. Spontaneous bone repair of the empty cavities took approximately 12 weeks, while integration of the cryopreserved allografts occurred after 9 weeks. However, no signs of new bone formation were found with the 200 microns pore size hydroxyapatite. In contrast, there was substantial production of bone within the 500 microns pore size implants at 12 and 26 weeks. Our results indicate that the pore size of the coralline hydroxyapatite influenced the development of bone in the implants in the cancellous bone bed of the rabbit femoral condyle. The results also show that spontaneous bone repair should be taken into consideration when the integration of implants is evaluated.
The excimer laser was thought to be an appropriate tool for the removal of bone cement without damaging the bone. However, due to its low ablation rate, its clinical use in total hip revision arthroplasty proved to be impossible. This experimental study was designed to evaluate the maximal ablation rate by adjusting the laser's parameters. Energy density, frequency, pulse duration, radiation area, quantity of pulses, and environmental conditions were varied in the experimental setup. Even with the best set of parameters the excimer laser was about ten times slower than, e.g., the carbon dioxide laser. The removal of 10 g bone cement takes about 1 h. Thus, complete cement removal by means of the excimer laser alone is not possible. However, selective application of the excimer laser in combination with other techniques could be discussed.
The purpose of the study is to establish data on the stability of an ACL replacement. In 40 human cadaver knees, either a mid patellar ligament third with a trapezoid bone block on one side was fixed on the femoral side in a 2-diameter drill hole, or a conventional interference screw fixation was applied. Average primary stability amounted to 570 N (+/- 100 N) for the bone-blocking technique, and to 402 N ( +/- 79 N) for the interference screw fixation. When statistically tested by variance analysis, stability was significantly higher for the bone blocking technique than with interference screw fixation (p < 0.05). Thus, when using a mid-patellar ligament third for ACL reconstruction, the new implant-free technique described here appears to be a practical and reliable method for femoral graft fixation.
In a retrospective study, 22 patients treated surgically for solitary or multiple myeloma between 1980 and 1993 were analysed. The main complaint was pain. A fracture was observed in 7 cases and motor-sensory impaired neurology due to spinal compression in 3. Apart from incisional biopsies, tumour resections, reductions (with and without stabilization by osteosynthesis) and endoprotheses were performed either at the extremities or on the spine. In addition, radiation and chemotherapy were included in the therapeutical concept. Early mobilization was achieved in all cases, and the 5-year survival rate (Kaplan-Meier method) was 48%. The results presented in this study demonstrate that a variety of surgical interventions can be of importance in the treatment of myeloma of the bone, ranging from biopsy or even curative resections in selected cases to endoprosthetic replacement. Thus, good functional results can be achieved and maintained over often long survival times.
The use of bone allografts is often essential in orthopedic surgery. Strict donor screening, including HIV testing 3 months postoperatively, is mandatory before a transplant may be used. Yet these measures do not definitely rule out the possibility of HIV transmission, as there is a window period before infection is revealed by blood testing. Accordingly, there is a need for virus inactivation methods that can be used on bone allografts. As radiation treatment and chemical methods have a number of disadvantages, we chose a moderate heat treatment of 65 degrees C for a series of animal experiments. In 12 rabbit femoral condyles, moderate-heat-treated bone allografts were implanted into 6-mm drill holes. Twelve normal allografts and 12 empty drill holes served as controls. Radiologic and histological evaluation up to 12 weeks postoperatively revealed slow spontaneous bone remodeling from the rim to the center of the empty cavities. Normal deep frozen allografts were quickly intergrated after a short period of osteoclast reaction around the transplant, with occasional bone bridges between host and allograft. The examination of heat-treated allografts showed no differences to the controls, including morphologic aspects and the time course of osteointegration. Five zones of bone repair and osteointegration were distinguished. We conclude that thermal treatment of bone allografts has adverse effects on osteointegration in the rabbit femoral condyle. Thus, it may contribute to improving safety in human bone transplantation.
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