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Strong porous tri-calcium phosphate ceramic has been fabricated, and investigated as a bone implant material. No foreign body reaction was observed, while osteoclastic activity was shown to be involved in biodegradation. Bone mineral was deposited directly onto the surface of the ceramic implant.
The authors reviewed the development of the carpal bone prosthesis implantations. The advantage of the silicone prostheses type Swanson was described opposed to the metal and acrylic prostheses. Silicone rubber prostheses replacing carpal bones were implanted in 56 cases (30 lunatum, 22 scaphoid, 4 trapezium) with success. To keep the well defined indication conditions is underlined by the authors. They created the home conditions of the carpal bone prostheses manufacturing.
Authors make an analogy between the principles of treatment of the fresh, potentially infected injuries with bone and soft tissue defects and of the already developed manifest infection of the hand. The principles of treatment are essentially the same. First of all the fixateur externe and the antibiotics containing globules are suggested for the sanation and prevention of the disease equally. Attention is called to the fact, that better results can be expected from the prophylaxis than from the attempts to make the process reversible. The beneficial synergism of the extrafocal fixation and the intrafocally acting antibiotics will help. One of the secrets of the good late functional results is the early restitution of the architecture of the bones of the hand. For this, the authors suggest the most modern replacement of bone in the form of primary delayed cancellous bone plasty, performed within two weeks.
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It was the purpose of this investigation to prove the biomechanical properties, the osteoconductive capacity and the degradation rate of alpha tricalcium phosphate (alpha TCP), a neutralized glass ceramics (GB9N) and a composite material (GB9N+copolymers). In a weight-bearing animal model six substitutes each were implanted in the medial tibial head of the right lower leg of adult Merino-sheep in a standardized surgical technique. After nine months the implants were harvested and prepared for histomorphological and histomorphometrical investigations (undecalcified Masson Goldner staining). For additional biomechanical testing of the specimens, non-operated bone blocks from the contralateral tibia as well as native implants served as controls. No significant differences for the maximum fracture load as well as for the yield strength were detected between harvested specimens and bone blocks from the contralateral tibia. However there were marked differences to ceramics that were not implanted. All substitutes showed osteoconduction, leading to a continuous ingrowth of new formed bone. However in the composite material soft tissue could be identified within the scaffold and there were signs of ongoing bone remodeling, nine months after implantation. The bone per tissue volume of alpha-TCP in conjunction to new bone (=percentage of trabecular bone volume plus percentage of residual substitute) was higher than for GB9N and the composite material. Nine months after implantation the percentage of residual alpha-TCP was 48%, it was 32% for GB9N and 28% for the composite. The intention of further studies should be to accelerate the degradation rates of substitutes and to improve biomechanical properties of implants by either modifying the chemical composition or combining materials with agents as, e.g. growth factors.
OBJECTIVE: To compare the mechanical properties of 2 configurations of a veterinary fixation system (VFS) for large animal long bones with dynamic compression plating (DCP). SAMPLE POPULATION: Eighteen pairs of Canevasit tubes (Canevasit; Amsler und Frei, Schinznach Dorf, Switzerland) (length, 170 mm; diameter, 47.5 mm; cortex thickness, 10 mm), aligned with a 10-mm gap, and stabilized with 2 DCP or 2 VFS implants. METHODS: Three groups (n = 6) were compared. Group 1 Canevasit tubes were stabilized with two 10-hole, broad 4.5-mm stainless steel DCP applied with both plates centered over the gap, in orthogonal planes parallel to the long axis of the tubes and staggered to allow bicortical fixation with ten 4.5-mm, 52-mm-long cortex screws each. Group 2 tubes were stabilized similarly with 2 VFS implants, each composed of a stainless steel rod (length, 167 mm; diameter, 8 mm), and 10 clamps were applied in alternating fashion left and right on the rod and fixed bicortically with ten 4.5-mm, 52-mm-long, cortex screws. Group 3 tubes were stabilized similarly, but using only 6 clamps/rod. All groups were tested initially in torsion within elastic limits and subsequently in 4-point bending, with 1 implant on the tension side, until gap closure occurred. RESULTS: None of the constructs failed, but all had plastic deformation after 4-point bending. No statistically significant differences were found among the 3 groups in torsional stiffness. Double DCP fixation was significantly stiffer and stronger in 4-point bending, compared with both configurations of double VFS fixation. CONCLUSIONS: The plate design was favored in this study. The VFS system may have to be adapted before further tests are conducted. Test modalities have to be chosen closer to clinical conditions (real bone, cyclic loading, closed gap). CLINICAL RELEVANCE: The veterinary fixation system has not yet proven its advantages for large animal long bone fracture repair. From the pure mechanical point of view, double DCP is the favored method for the treatment mentioned.
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This paper describes a new technique for the closure of oro-antral fistula/communication, in which both hard tissue (bone) and soft tissue closure is achieved. The sandwich technique utilizes a suitable bone grafting material sandwiched between two sheaths of Biogide (a resorbable membrane) for the hard tissue closure of oro-antral communication post traumatic exodontia. The bone grafting material utilized for this case was Bio-oss. The result obtained was excellent with regeneration of sufficient bony tissue to allow placement of an endosseous implant. This sandwich technique is a simple and excellent technique for the closure of oro-antral communication, especially when subsequent placement of endosseous implant is considered without the need of donor site surgery for bone grafting. The otorhinolaryngologists and oral and maxillofacial surgeons should find this technique very useful in the closure of oro-antral fistulae.
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In a retrospective study validated by a standardized clinical and radiological examination, the bone regeneration in 90 patients with cystic mandibular defects was examined. In 50 patients bony defect reconstructions with human demineralised bone matrix (HDBM) were carried out, while in a comparable group of 40 patients the hollow pockets were left to regenerate bone spontaneously. The bone regeneration after the implantation of human demineralised bone matrix (HDBM) was subjected to a comparative validation. Osteoinductive proteins present in HDBM (bone morphogenetic proteins) can diffuse into the implant seat and induce new bone formation (osteoinduction). A markedly faster and more thorough bone regeneration was demonstrated after the surgical therapy of cystic mandibular lesions with HDBM than without. HDBM also proved to be exceptionally biocompatible.
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Using magic angle sample spinning 31P NMR spectroscopy, we studied NMR parameters of hydroxyapatite, calcium-deficient hydroxyapatite, and beta-tricalcium phosphate. These data were compared to rabbit bone parameters. Rabbit bone spectrum is similar to deficient hydroxyapatite spectrum but high-power proton decoupling did not modify its linewidth. Moreover, both bone T1 and deficient hydroxyapatite T1 were much longer than pure hydroxyapatite T1 and beta-tricalcium phosphate T1. We used these results to develop quantitative analysis of newly deposited bone inside beta-tricalcium phosphate implants in rabbit. This method made it possible to demonstrate the effect of porosity on osteoinduction of biomaterials.