Note: Descriptions are shown in the official language in which they were submitted.
~za~
~IOD~TRUCTIVE MA~RIA~ FOR BONE
~I~ATION ~`LEME~S
This in~ention relates to modical technique, and more
par~icularly it relates to biodestructive materials used
for fixation of bone -tissues.
Biodes-tructive material can be used in medical techni-
que for -the manufacture of connecting elemen~s for rsndering
medical aid in i~juries. Such eleme~ts are, for example, va-
rious pins, staples; xods, plates, etc.~ intended for f`ixa-
tion of bones in frac-tures.
Known in the prior art are variou~ connecting elements
manufactur~d ~rom metal alloys. But they have certai~ dis-
advantages, which are in the firsb instance associated with
the removal of the fixation elemen-ts from the reg~nerated
bo~e by sur~ical methods. Moreover, metal alloys often pro-
duce marked reactions in bone tissues, and even ga~ and
toxic products can be produced by alloys co~taining mag~esium~
~el,u pl, s
A4~oy~ were made -to use polymers, e.g. polymethyl meth-
acrylate, for the manufacture of bone f ixa-tion elements
(Blumin, I.I. Kheifitz, A.V., "Vestnik Ehirurghii i Anesteæi-
ologhii, 1955, 11, 80 - 83). But polymethyl methacrylate does
no~ have the required strength and is not resolved in the
body, which again involves repeated operations for extraction
of the fixtures.
~ nown in the prior art are also methods for the manufact-
ure of bone fixatio~ elements fxom the protei~ fractio~s o~
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human blood (Golovi~, G.V., '~oprosy Voss-tanovitelnoi Khir-
urghii, Travmatologhii i Ortopedii", S~erdlo~sk~ 1957, 6,
211 - 217). But th~ physico-mechanical properties of such
materials do not meet the requirements, while the time of
its resolu-tion in the body is shorter than the time re~uir-
ed ~or the regeneration of the bone tissue~
Attempts were made to use materials consistin~ o~ a
rein~orcing componsnt in the form ~ ~ibres or ~abric, for
example, glass ~ibre, carbon fibre, glass fabrics, and a
polymer bi~di~g component, for example~ unsaturated poly-
ester~ epoxy, polyamide, etc., but despite the high ~trength,
bone con~ecti~e fixtures manufa¢tured out of these materials
proved lne~eative because they are either toxic or do not
resol~e in the body.
The object of the invention is to provide a biodestruct-
ive material ~or the manufacture of bone fixation elame~ts
which would b~ able to resol~e i~ ths body at the wan~ed
terms, would be harmless, and would possess the high physico-
mechanical properties ensuring reliable ~ixation o~ bone
fra~ments.
Accordlng to the invention, propo~ed is a biodestructive
material for the ma~u~acture of bcne fixation elements compr~
ising a matrix of a non-toxic rssolvable polymer consisti~g
o~ hydrophilic and hydrophobic repsat units3 and a rein~orc-
ing compone~t made out of non-toxic resol~able ~ibres or
threads,.
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~3~
The hydrophilic uni-ts~ which enter into -the matxix
polymer ~xe, for example7 N-~inyl pyrrolidone, acryl amide,
vinyl caprolactam, monomethacrylic ester of ethylene glycol,
methacryl~nide, acr~lic acid~ and also any o-t~er compound
which ~orms water-solllble non-toxic polymers or polymers
u~limi-tadly swellable in water.
~ he hydrophobic units which enter i~-to the ma~rix poly-
mer are, for e~ample, methyl m0-thacrylatea butyl methacryl-
ate, vinyl acetate, alpha-ethoxycyanacrylate~ ethyl acryl-
ate, and also other compounds which form ~on -toxic water-
-insoluble pol~mers.
~ he fibres used as reinforcement for the bone fixation
ol~ment$ are, for example, sg~the-kic non-toxic fibres or
threads o~ polyamide, oxycellulose, poly~i~yl alcohol, or
their mixtures, and also natural non-toxic resolvable ~ibres
and -threads, such as catgut~ collagen, dextxan ~ibres and
thread~, and the like.
As has been sta-ted above, proposed is a novel biodeæt-
ructive material used ~or fixation of bone ~ragme~ts~ which,
according to the invention, comprises a matrix of a non-tox-
ic polymer formed from hydrophilic and hydrophobic units and
a reinforcing component of non-toxic threads or fibres resol-
vable i~ the body~
Said polymer is prepared by the known methQd, i.s~ by
polymerization or copolymerization of the starting hydrophil-
ic and hydrophobic monomexs i~ a medium o~ inert solve~s,
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20~
~or example, in benzen~, toluene, in the presencc of initia-
tors of radical pol~meriza~ion, for e~ample, dinitrile azo-
-bisiisobutyric acid, or 4j4-azo-bis-(4-cyanpentonic)acid.
It is recommended that the fi~ished polymer contained ~rom
20 to L~ per cent by weight o~ hydrophilic unit3, which en-
sures bettsr resultæO
If the polymer contains less than 20 per cent o~ h~dro-
philic units, the biodestruction of the polymer in the pati-
ent body will be more protracted. If the matrix polymer con-
tains more than 40 per cent of the hydrophilic units, the
material swells in excess and does not ensure -the required
strength of the material during -the period of bone fragment
consolidatio~.
~ he proce~s for the manufacturo of the biodestructive
material ¢on~ist~ in that the ~tarting polymer is di~solved
in an inert organic ~olvent, for exa~ple, in acetone, tolue-
ne, or ethyl acetate, and the obtained solution is used to
impregnate threads or fibres of the reinforcing component.
~he material is then dried to remove the solvent. ~he obtain-
ed material contains the matrix in the quantity from 20 to
50 per cent and the rei~orcing component from 50 to 80 per
cent by weight. Said ~eight proportions of the ~atrix a~d
the rein~orcing compone~t ensure the required physico-mecha-
nical properties o~ the ma-terial intended for the fixation
of fractured bones.
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~:~L3~;~0~
Theproposed biodestructive material o~ers the follow-
ing advantages
lo It rules out the necessity o~ an additional operation
for the extraction o~ the connecting element.
2. Makes it po~sible to adjust the ~3ize of the conneot-
ing element straight during the operation b~ usin~ mechanical
tools so that it might fit properly each particul~r ~ragme~t
of bone without limiting mobility o~ the adjacent joints dur-
ing ths period of the bone fragment co~solidatio~.
Variou3 connecting elements, such as pin~, rods, staples,
can be manufactured out o~ the pxoposed biodesctructlve mate-
rial; it iB placed into compression moulds and pressed at a
temperature o~ ~ooa and speci~ic pre~sure to 300 kg/~q.om.
~he mould is -then cooled and the fini~hed ar-ticle extracted.
It is recommended to use a biodestructive material in
which the matrix i~ a copolymer of methyl methacrylate a~d
~-vinyl pyrrolidone, and the rei~orci~g elament is polyamide
~ibre. The star-ting components o~ this material are readily
available commercial product~, and the physico-mecha~ical
properties of the resulting material adequately meet the ra-
quireme~tsu
For a better understanding o~ the invention, the follow-
ing examples of i-ts practical embodiment are given by wa~ il-
lustratio~.
~:~3~;~0~3
28.8 g of polyamide fibre are impregnated with acetone
solu-tion containing 11.2 g of copolymer of me~hyl methacryl-
ate and ~-vinyl pyrrolidone. ~he conte~t o~ N-~inyl pyrroli-
done in the copolymer is 31.2 per cent by weight. r~h~ ~ibre
is then dried -to remove the solvent and the obtained mate-
rial is placed i~ a compression mould where it is pressed
at a temperature o~ 160C and a pressure o~ 280 kg/sqOcm,
The mould is then cooled to a temperature o~ 40C~ the pres
sure is released, and the article removed ~rom the mould.
The article prepared in this example is a red, 12 mm
in diameter ~nd 410 mm long. It has the ~ollowi~g charac~-
eris-tics:
Plexing strength 2700 kg/s~.cm
elasticitg modulus in bend 45,200 kg/sq.cm
rssolution tims in a livi~g
body about two years
period of reliable fixation
o~ bone fragme~ts 8 - 9 month8
Exam~le 2
The biodestructive ma~erial a~d the article out of it
are prepared b~ -the procedure described in Example 1, e~-
cept -that 8 g of` the copolymer o~' methyl methacrylate and
N-vinyl pyrrol~done and ~2 g o-~ polyamide fibre are used.
The ~inished ar~icle is a rod ha~ing the same d~me~sions
as in Example 1. Its characteristics are as follows7
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flexing strength 2400 kg~sq~cm
elas-ticity modulus i~ bend 32?600 kg/s~.cm
resolution time about two ge~rs
period of reliable fixa-tion
of bone fragments ~ - 9 months
~ .
~ he biod~structive material and the connectiYe element
out of it are prepared by -the procedure described in Exampla 1
except that 20 g of the copolymer of methyl methacrylate a~d
N-~inyl pyrrolidona and 20 g of polyamide fibre are used.
The article manufactured of this material is a rod h~vi~g the
same dimensions as specified in E2ample 1. ~he rod has the
followin~ characteristics:
flexing s-trength 2610 ~g/sq.cm
elastici-ty modulus in be~d 39~0 kg/~cm
resolution time about two years
period of reliable fi~a-tion
of bone fragme~ts 8 - 9 months
A biodestructive material, prepared from 30.1 g of the
copolymer of methyl methacrylate and ~-vinyl pyrrolidone
(N-vinyl pyrrolidone content is 39~6 per cent bg wei~ht) and
66.9 g o~ carboxyethyl cellulose fibre (PD 330)9 is used for
th~ manufacture of a rod, 13 mm in diameter a~d 415 mm long.
~he procedure is the same as described in Example lo The rod
~as the followi~g characteris~ics:
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~30;20~
~lexing stre~gth 1890 kg/s~.cm
elasticity modulus in be~d 25,000 k~/s~cm
resolution time 1,,7 year
period o~ reliable fixation
o~ bone fragments 4,.5 - 6 mon-ths
Exa~
~ he biodestructive ~aterial and the article out of it
are prepared by a procedure described in ExampIe 1, excep-t
that 28.2 g of the copolymer of meth~l methacxylate ~nd ~
nyl pyrrolidone ~-~inyl pyrrolidone conten-t o~ -the copolymer
being 33~6 per cen-t by weight) and 64.7 g of polyamide fibre
and ~,1 g of carboxymethyl cellu}ose Eibre are u~ed. ~he red
manuEactured out of this ma-terial ha~ the dime~ions ~peci-
~ied in Example 4 a~d i9 charac-terized by the followlng pro-
perties:
flexing strength 2840 k~/sq~cm
alasticity modulus in bend 259000 kg/s~cm
rssolution time 21 months
period of reliable fixation
of bone fragments 5 - 7 mont~s
~xample 6
The biod~structive ~aterial and -the connective eleme~t
out of it are manufactured b~ the procedure described in
~xample 1, e2cept that 20.1 g of the copolymer of mathyl
methacrylate and N-vin~l p~rrolidone (N-vinyl pyrrolidone
content of the copolymer being 35.2 per ce~t by weight) and
12,7 g of catgut fibres, and 38.2 ~ o~ polya~ide fibres are
used -to prepare the matexial. ~he fixation rod ma~u~actured
from this material has the dimensions speciEied in Example 4
and is characterized by the following-propertifls~
~lexing strength ~160 kg/sq.cm
elasticity modulus in bend 9800 kg/sq.cm
resolution time 1~ year
period oE reliable fixatiorl
of bone fragments ~ - 5 months
Example 7
~ he biodestructi~e material and -the cor~ecting elements
out of it are prepared by the procedure described in Examp~
le 1, except that 20.1 g of a copolymer o~' butylmethacryla~e
and ~-vingl pyrroiidone, and 69.2 g of polyamide :Eibre are
used to manu-Eacbure the ma~erialO The rod prepared from thi~
material has the ~ollowing characteristics:
fleæing stre~gth 1920 kg/s~.cm
elas-ticit~ modulus in bend 9200 k~/sq.cm
resolution time 2~7 yeax
period of reliable fixation
of bone fragments 9 months
~ he biodes-tructive material and the connectin~ elem~nt
out o~ it are manufaGtured by the procedure described in
Eæample 1, except -tha-t ~2 g of a copolymer o~ acrylamids
and ethyl acrylate (t~e acrylamide content of the copol~mer
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;208
being 22 per sent by weight), a~ld 69 g o~ carboxyethyl c~l~
lulose fibres are u~ed -to prepare t~e material. ~he article
mar~actured ~rom this ma-terial is a fixa-tio~ rod ha~ring the
f ollowi~g characteristics:
~lexing stre~gth 1790 k@;/sqOclrl
ela~ticity modulu~ n bend 8700 kgJsq.cm
resolution-time 1.3 year
period of reliable f ixation
of bone fragme~ts ~ - 5 moxlth~
