Implantation of p(HEMA)-collagen composite into bone.

The replacement of bone defects is very important in clinical practice. This study compares biological properties of poly(2-hydroxyethyl methacrylate)-collagen composite with those exhibited by pure p(HEMA), an insoluble fraction of calf skin collagen (ISC-40) and demineralized bone matrix after implantation into pig or dog femurs. The levels of biodegradation or destruction of implants and healing of bone defects were studied using X-ray photography, histology and enzyme histochemistry. The results indicated a significant effect of collagen on biological destruction of the p(HEMA)-composite implants; even a minute amount of collagen influences this process dramatically. A stimulatory action of collagen on new bone formation may be of importance in bone defect healing.

[Problems in admitting and eliminating children from sports training schools]. / K problematice zarazování a vyrazování detí ze sportovních skol.

The physical and mental load of children enlisted in the system of preparation for top sports is great. It is therefore essential to ensure very careful health care and also very strict criteria for enlistment of children to avoid pathological adaptation to the sports load. Specialized sports training of 14-18 hours per week may, in case of incorrect compensating activity, be the basis for the development of secondary changes. In the selection it is important to adhere to criteria pertaining to health, performance, function and development and to evaluate them in relation to the character of the sports discipline and preparation for attaining top performance. Based on six years' experience, it is possible to indicate for the purpose of orientation the risks of different sports for the locomotor system during ontogenesis. Cooperation of orthopaedists and specialists in sports medicine is the prerequisite of restricting possible negative sequelae of local and general overburdening. The conclusion must be always the synthesis of all examinations and conclusions must not be drawn from a single examination. The authors draw attention to mistakes in the evaluation by specialists as a result of lacking knowledge as regards the loading of the organism by training in these schools.

[Experimental implantation of hydrogel into bone]. / Experimentální implantace hydrogelu do kosti.

In spite of the rapid development of various natural and artifical implants of bone tissue, bones or whole joints, no material was found as yet which would maximally resemble the structure of the bone tissue and would also be maximally compatible. The present study deals with the application possibilities of unsoluble hydrophilic gels (hydrogels) as substitutes of bone tissue in experiment. The study concerns above all their biocompatibility with regard to the porous qualities of the implant and to its chemical structure, and evaluates their behaviour in the spongious and compact bone. It was used polyhydroxyethylmethacrylate (polyHEMA) which is crossling with small amount of glycoldimethacrylate when by changing of ratio monomer: water is possible obtain from homogeneous to macroporous structure of polymers. The macroporous structure was increased and the surface of the macroporous structure of polymers. The macroporous structure was increased and the surface of the macroporous, sinterted HEMA modified and implanted. The so-called double porosity was thus obtained. The implants were prepared in the form of cylinders (3.5 mm in diameter) in 8 different modifications and surgically implanted into the subtrochanteric and supracondylic part of the rabbit femurs. 42 animals were operated on. The obtained preparations were then evaluated macroscopically, and histologically processed in half-thin cuts (3-4 micrones). 124 samples were thus obtained. Some samples were radiographically contrasting. The rabbits were killed at intervals from 1-6 months, i.e. 32-193 days. It was found that the hydrogels modifications used in the experiment are biocompatible, their compatibility increasing in dependence on the increasing porosity. The non-porous and microporous hydrogels are not compatible and are damarked. The sintered macroporous gel is surrounded by a thin fibrine membrane signifying a high degree of compatibility with the bone tissue. By adding metacrylate acid to the hydrogel, the adhesivity of the macrophages increases markedly. There also appears the destruction of the polymer, marked, above all, in the spongious bone. The gel is actively degraded in the marrow, although the direct phagocytosis can be proved. At degradation of the implant in the compact bone the activity of the macrophages is belated; at application of the gel without methacrylate acid it does not occur even after 193 days and the implant is pervaded only by the bone beams. When adding methacrylate acid to the polymer degradation occurs, in which process there play also an active role the blood vessels pervading the site of the gel implantation.(ABSTRACT TRUNCATED AT 400 WORDS)

[Spinal deviations in sports medicine practice]. / Abweichungen der Wirbelsäule in der sportmedizinischen Praxis.

The examination of the spine in sportsmen is imperative. The anatomical configuration reveals the X-ray examination, where the radiation is, however, considerable. Our apparatus eliminates the danger of radiation, using a non-invasive method of examination, at the same time enabling to state the grade of curvature both in the frontal and the sagittal level. It also secures the standard posture at examination. The authors have also found the conclusive physiological deviation of the single curvatures of the spine, and examined various groups of sportsmen in which the grade of pathological curvature was evaluated.

Experimental implantation of hydrogel into the bone.

The present study deals with the application and possibilities of insoluble hydrophilic gels (poly(2-hydroxyethyl methacrylate] as substitutes of bone tissue experimentally. Their biocompatibility is examined with regard to the porous qualities of the implant and to its chemical structure, and their behavior in the cancellous and compact bone is evaluated. It was found that the modifications of hydrogels used in the experiment are biocompatible, with the compatibility increasing in proportion to increasing porosity. The nonporous and microporous hydrogels are not compatible and are demarcated. The sintered macroporous gel is surrounded by a thin fibrin membrane. By adding methacrylic acid to the hydrogel surface, adhesion increases markedly. Marked destruction also appears in the polymer especially in the cancellous bone. By an active destruction of the polymer, no direct phagocytosis can be proved. Upon breakdown of the implant in the compact bone the activity of the macrophages is delayed. When the gel without methacrylic acid is used alone, destruction does not occur even after 193 days. When methacrylic acid is added to the polymer surface, destruction does occur and the implant is filled only by bone trabeculae.

Poly(HEMA)-collagen composite as a biomaterial for hard tissue replacement.

This article briefly reviews the possibilities for hard tissue replacement with a new biomaterial. The basic differences found experimentally for polymer (HEMA) and collagen composite at the biological environment are stressed. The influence of the collagen distribution and matrix porosity of composite material on biodegradation is also discussed.

[Use of a new type of hydrogel in bone surgery]. / Moznosti pouzití nového typu hydrogelu v kostní chirurgii.

The authors submit information on the properties of a new macroporous hydrogel, which was synthetized specially for use in bone surgery. In animal experiments the authors evaluate microscopically the biocompatibility and process of biodegradation of the implant in osseous tissue.