FR2654001A1 - ELEMENT FOR TRIMMING IN A DEFECT OF THE BONE AND A REGION OF OSTEOPOROSIS. - Google Patents

Abstract

The invention relates to a lining element (10, 20) for lining a bone defect and a region of osteoporosis, which contains a calcium phosphate compound and which has a cylindrical shape (10 ) or a polygonal prismatic shape (20). The cross section profile is practically the same over the entire length of the element, and its cross section length / diameter ratio is in the range of 0.1 to 10.

Description

The present invention relates to an element for the lining in a

  bone defect and an osteoporosis region and more particularly such a packing element containing a

composed of calcium phosphate.

  Osteoporosis is a syndrome in which the quantity of bone is reduced for various reasons. The growth of human bone is finished at around 20 years, its length and width becoming maximum at this age and its quantity reaching a maximum at age 20 to 30 However, when approaching from middle to old age, the bone becomes thinner and the amount of bone is reduced, even in healthy people, although the size of the bone remains practically unchanged Most importantly, the amount of bone is reduced rapidly in postmenopausal women and in men and women 65 years of age or older In addition, the amount of bone can be reduced by diseases of the internal secretion , stomach, intestines, liver or kidney or as a result of the administration of drugs such as glucocorticoids, causing osteoporosis When you have osteoporosis,

  bone fracture can be easily caused by reduction

  mechanical strength of the bone Examples of typical bone fractures caused by osteoporosis include compression fracture of the spine, fracture of the

  neck of the femur and fracture of the distal portion of the radius.

  Until now, no treatments have been found

  treatment of osteoporosis, except administration of drugs

  ment such as female sex hormones, active vitamin D or calcitonin However, it was not possible to correct with drug therapy the centering of a vertebra which was compressed or beveled under the effect of 'a compression fracture or positively increase the amount of bone. On the other hand, it is known that compounds of calcium phosphates are capable of forming bone and useful as a filling material to fill a defect or a hollow portion of the bone. However, when these compounds are applied to osteoporosis therapy, it is necessary to introduce a predetermined amount of the calcium phosphate compounds into a particular site where the amount of bone is decreased.

  in the case of a deeper operating site, we encounter difficulties

  Considerable cultivation of the filling material Although these difficulties can be overcome by the use of a suitable dispensing device, the known types of filling material composed of calcium phosphate compounds have the disadvantage of insufficient fluidity and cannot be easily injected through the dispenser In the case where the packing material is applied to osteoporosis therapy, it should be expected that the packing material will remain fixed for a long time in the site where the amount of bone has

  been reduced to increase the amount of bone.

  We proposed, for example in the Japanese patent application put to the inspection of the public n 268562/1987, a material

  packing for osteoporosis containing particles of com

  laid calcium phosphates, each particle having a ratio of the major axis to the minor axis in the range of 1: 1 to 1: 5 and an angle of rest in the range of 100 to 45 Although the problem of insufficient fluidity particles of calcium phosphate compounds can be removed to some extent by this prior art packing material, packing cannot be performed with ease in a deep lesion site In addition, due to the particle shape random, it may happen that the filling cannot be carried out when the filling material is extruded by the distributor in one direction In addition, sufficient bone-forming capacities cannot be achieved when the calcium phosphate compounds are used in combination with other substances

  such as a bone morphogenesis protein or fibrin.

  A main object of the present invention is to provide a packing element for packing a bone defect and an osteoporosis region which has excellent fluidity and which can be easily poured directly or applied by a

  distributor in the site of the lesion.

  Another object of the present invention is to provide a packing element for packing a bone defect and an osteoporosis region which can be introduced into sites.

  deep into the organism by means of a distributor.

  Another object of the present invention is to provide a filling element for filling a bone defect and an osteoporosis region which has excellent fluidity and which makes it possible to reduce the area of resection or incision. When the packing element is introduced using a device

distributor.

  Another object of the present invention is to provide a packing element for packing a bone defect and an osteoporosis region which, despite its improved fluidity, can

  remain fixed on the site for a long time after its application

  tion to allow it to increase the amount of bone.

  The above and other objects, features and advantages of the present invention will become more apparent from the

  reading of the description which will follow.

  According to the present invention, there is provided a packing element for packing a bone defect and an osteoporosis region, the packing element containing a calcium phosphate compound and having a shape chosen from a shape cylindrical and a polygonal prism shape, the shape of the cross section being practically the same over the entire length of the packing element and the ratio of the length to the diameter of

  cross section in the range of 0.1 to 10.

  In the accompanying drawings, Figure 1 is a schematic perspective view showing a cylindrical packing element according to the present invention; and Figure 2 is a schematic perspective view showing a prismatic packing element with a polygonal base

according to the present invention.

  The present invention will be explained in more detail below.

below.

  The calcium phosphate compounds used in the

  present invention include tricalcium phosphate, hydroxy-

  apatite, tetracalcium phosphate, oxyapatite, calcium pyrophosphate, fluoroapatite and mixtures thereof Particularly preferred is one or more calcium phosphate compounds chosen from tricalcium phosphate, hydroxyapatite, fluoroapatite and tetracalcium phosphate a high speed of new bone formation Particularly preferred is hydroxyapatite, especially hydroxyapatite sintered at 500 C or more and better still at 700 C or more, since it ensures the speed of formation of new bone most high and has a lower solubility, so that it fixes for an extended period on the

  site of the reduced amount of bone to fulfill its function of osteo-

  genesis Although there is no upper limit to the temperature

  heat treatment, it must be lower than the temperature

  The decomposition of hydroxyapatite which otherwise starts to decompose The calcium phosphate compounds used in the present invention can be produced from natural bone or synthesized artificially by a wet process, a process using

  dry or a hydrothermal process in a manner known per se.

  The packing element in the present invention should be in the form of a cylinder 10 as shown in Figure 1 or a polygonal prism 20 as shown in Figure 2 The cross section profile of the column does not need to coincide with the tubular profile of the dispenser, provided that the dispensing operation is not hampered, although this is preferred The cylindrical or prismatic polygonal shape of the packing element can be suitably chosen depending on whether the profile cross section of the dispenser container and the dispenser tube

  has a cylindrical or prismatic polygonal shape.

  The cross section diameter of the packing member used in the present invention is preferably 0.2 to 10 mm and more preferably 0.2 to 5 mm If the cross section diameter exceeds 10 mm, the formation of fresh bone around the filling element is delayed while if the cross-sectional diameter is less than 0.2 mm, the filling material is carried by the blood, etc. without being fixed in the portion to be filled so that

  one cannot expect sufficient properties of osteo-

  genesis For the convenience of the dispensing operation, the cross-sectional shape or profile of the compound packing element

  of calcium phosphate of the present invention should be practiced

  the same over its entire length In addition, in order to introduce the packing element into deep bone defect sites or deep regions of osteoporosis, the ratio of length to cross section diameter of the element trim must be

in the range of 0.1 to 10.

  The poly- cylindrical or prismatic packing element

  gonal of the calcium phosphate compound used in the present invention may preferably be porous or of dense sintered texture IL may also be used in combination with

  substances capable of further promoting its osteo-

  genesis such as a bone morphogenesis protein and / or fibrin. The packing material of the present invention is

  in the form of particles of calcium phosphate compounds.

  When using a compound of natural origin or a compound produced by the dry process, these particles can be produced by spraying the calcium phosphate compounds, addition

  of a solution of a binder such as polyvinyl alcohol or methyl-

  cellulose, to the powders thus produced of calcium phosphate compounds, to thereby produce a moderately plasticized mixture, extrusion of the mixture in an extruder such as a suitable two-axis granulator, to form the shape of a desired polygonal cylinder or prism and sintering of the products thus molded at a sintering temperature of 700 to 1200 C. When using the compound produced by the wet process or the hydrothermal process, the particles can be produced by drying a suspension of the calcium phosphate compound in situ and grinding of the dried mass Or alternatively, the particles can be obtained by spraying the calcium phosphate compounds, addition of the above-mentioned binder solution to the powders thus produced to produce a moderately plasticized mixture, molding of the mixture plasticized in the form of a cylinder or a polygonal prism and

  sintering of the particulate products thus molded.

  The poly- cylindrical or prismatic packing element

  gonal of calcium phosphate compound used in the present invention may be contained directly in a suitable dispenser However, to further facilitate the dispensing operation and avoid the need to repeat insertion of the dispenser into a bone defect or region osteoporosis and its

  removal, thereby reducing the duration of the surgical operation

  wedge, for example the packing element is first introduced and stored in a suitable container and the container is preferably introduced into the dispenser For operational safety, this container is preferably made of a material

  sterilizable, such as polypropylene or polyethylene.

  The present invention is illustrated below by a

  specific non-limiting example of implementation.

Example

  Dried hydroxyapatite produced by the wet process was sprayed with an average particle size of 0.5 to

  1.0 mm after addition of a polyvinyl alcohol solution.

  Then, the powder thus produced was molded into particles each having the shape of a cylinder 2 mm in diameter of cross section and 3 mm long using a two-axis granulator, not shown, and sintered at 950 ° C to produce a packing element in hydroxyapatite particles each having the shape of a cylinder of profile of uniform cross-section or the like The packing material produced was loaded into a dispensing device and introduced into a bone defect and a region of osteoporosis The lining material could be easily introduced into the lesion sites and the results of therapy

were satisfactory.

  Comparative Example A packing material in hydroxyapatite particles was prepared in the same manner as in the example above, except that the cross-sectional advantage of the particles in the diametrical direction was practically non-uniform and variable and the diameter with a long axis was chosen to be 20 mm. Although attempts have been made to introduce the filler produced in the lesion site using a dispensing device in the same manner as in the example above, it has been found that It was impossible to introduce the packing material in this way because of the sealing. The calcium phosphate packing compounds according to

  the present invention, cylindrical or prismatic polygo-

  nale, for filling a bone defect and an osteo-region

  porose can be easily introduced in a prescribed amount into a desired site of injury to exert an effect in osteoporosis therapy which was thought to be difficult to cure completely. Also, the packing material of the present invention can be easily applied in a deep site in the body while the incision area necessary for

  the operation can be significantly reduced.

Claims (4)

  1 A packing element (10, 20) for filling a bone defect and an osteoporosis region, the packing element containing a calcium phosphate compound and having a shape chosen from a cylindrical shape (10) and a polygonal prism shape (20), the shape of the cross section being practically the same over the entire length of the packing element and the ratio   from the length to the cross-section diameter being in the inter- valley from 0.1 to 10.   2 packing element (10, 20) according to claim 1, characterized in that said calcium phosphate compound is chosen from tricalcium phosphate, hydroxyapatite, tetracalcium phosphate, oxyapatite, calcium pyrophosphate,   fluoroapatite and their mixtures.   3 packing element (10, 20) according to claim 1, characterized in that it has a cross section diameter in the range from 0.2 to 10 mm.   4 packing element (10, 20) according to claim 1, characterized in that it also contains an additive chosen from   a bone morphogenesis protein, fibrin and mixtures thereof.