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WORLD INTELLECTUAL PROPERTY ORGANIZATION 
International Bureau 




INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) 



(51) International Patent Classification 5 : 
A61L 25/00, 27/00,31/725 



A2 



(11) International Publication Number: WO 91/17777 

(43) International Publication Date: 28 November 1991 (28.1 1.91) 



03 

m 



(21) International Application Number: PCT/US91 /03596 

(22) International Filing Date: 22 May 1991 (22.05.91) 



(30) Priority data: 
526,638 



22 May 1990(22.05.90) 



US 



(71) Applicant: UNIVERSITY OF FLORIDA [US/US]; 223 

Grinter Hall, Gainesville, FL 32611 (US). 

(72) Inventors: WALKER, Dixon, R. ; 6322 SW 37 Way, Gain- 

esville, FL 32608 (US). HENCH, June, Wilson ; 3948 
NW 23 Circle, Gainesville, FL 32605 (US). RAMER^ 
Marc ; 3301 SW 13 Street #A-107, Gainesville, FL 32607 
(US). HENCH, Larry, L. ; 3948 NW 23 Circle, Gaines- 
ville, FL 32605 (US). 



(74) Agents: FRANK, Steven, J. et al.; Cesari and McKenna, 
30 Rowes Wharf, Boston, MA 02110 (US). 

(81) Designated States: AT (European patent), BE (European 
patent), CA, CH (European patent), DE (European pa- 
tent), DK (European patent), ES' (European patent), FR 
(European patent), GB (European patent), GR (Euro- 
pean patent), IT (European patent), JP, LU (European 
patent), NL (European patent), SE (European patent). 

Published , , , , 7 . . , 

Without international search report and to be republished 
upon receipt of that report. 



1 

5s- 

G 

o 
o 

3 



(54) Title: INJECTABLE BIOACTIVE GLASS COMPOSITIONS AND METHODS FOR TISSUE RECONSTRUCTION 
(57) Abstract 

An injectable hyaluronic acid particulate bioactive glass composition useful for the repair reconstruction, "placement, 
m^iSS^SSL of ha P rd bone or soft tissue anatomic structure, the composition of the glass falhng w.thm Re 6 .on 

E of the compositional boundary diagram of Fig. 4. 



FOR THE PURPOSES OF INFORMATION ONLY 



Codes used to identity States party to the PCT on the front pages of pamphlets publishing international 
applications under the PCT. 



AT 


Austria 


BS 


Spain 


MG 


Madagascar 


AU 


Australia 


PI 


Finland 


ML 


Mali 


BB 


Barbados 


FR 


France 


MN 


Mongolia 


BE 


Belgium 


GA 


Gabon 


MR 


Mauritania 


BP 


Burkina Faso 


GB 


United Kingdom 


MW 


Malawi 


BG 


Bulgaria 


GN 


Guinea 


NL 


Netherlands 


BJ 


Benin 


GR 


Greece 


NO 


Norway 


BR 


Brazil 


HU 


Hungary 


PL 


Poland 


CA 


Canada 


IT 


Italy 


RO 


Romania 


CF 


Central African Republic 


JP 


Japan 


SD 


Sudan 


CG 


Congo 


KP 


Democratic People's Republic 


SE 


Sweden 


CH 


Switzerland 




of Korea 


SN 


Senegal 


CI 


Cote d'lvoirc 


KR 


Republic or Korea 


SU 


Soviet Union 


CM 


Cameroon 


LI 


Liechtenstein 


TO 


Chad 


CS 


Czechoslovakia 


LK 


Sri Lanka 


TG 


Togo 


DE 


Germany 


LU 


Luxembourg 


US 


United States of America 


DK 


Denmark 


MC 


Monaco 







WO 91/17777 



PCT/US91/03596 



INJECTABLE BIOACTIVE GLASS COMPOSITIONS 
AND METHODS FOR TISSUE RECONSTRUCTION 



BACKGROUND OF THE INVENTION 

yield of the Invention 

The present invention relates to novel injectable bio- 
active glass compositions for the repair of hard bone or soft 
tissue of human and non-human animals. 

Description of th e Prior Art 

It has been common practice in plastic, otolaryngological 
and other surgeries for many years to inject or place within 
tissues a variety of artificial substances to repair or 
reconfigure anatomic structures. For example, Teflon particles 
have been introduced into the vocal cord and more recently into 
periureteral and periurethral tissues with mixed results. 
Disadvantages associated with this procedure include long-term 
progressive foreign-body reactions and migration and distant 
embolism associated with very small particles. Considerable 
research has been conducted to discover substitutes for Teflon 
and other conventionally employed artificial materials. 

Urinary incontinence is a common accompaniment to diseases 
such as spina bifida and exstrophy of the bladder. The reasons 
for the incontinence are multifactorial and include hyperactive 
bladder pressure, small-capacity bladder and decreased urethral 
resistance. In patients who cannot void voluntarily (who do 
not have volitional control) , the preferred method of 
management is to place the patient in urinary retention and 
empty the bladder with clean inter-mittent catheterization. 
This has become the hallmark of urologic management in a large 
percentage of patients with spina bifida. Successful 
management of such patients requires an adequate bladder 
capacity, low intravesical pressure and a normal-to-high 
urethral resistance. Patients with spina toifida and exstrophy 
of the bladder often have anatomic and physiologic findings 



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that are not conducive to urinary retention and clean 
intermittent catheterization. These findings include small 
bladder, high intravesical pressure and low urethral 
resistance. Low bladder capacity and increased intravesical 
pressure can, occasionally, be managed with anticholinergic 
medication, but this is of limited usage and most patients 
require enlargement of their bladders and creation of a low 
pressure system by augmentation cystoplasty (applying a cap of 
bowel to the bladder) . Urethral resistance can be minimally 
increased with pharmacologic therapy, but his is generally 
unsatisfactory. Artificial urinary sphincters have been 
developed which can be inserted surgically. These require an 
open surgical operation and mechanical failure is common. 

Urethral resistance can be increased by bladder neckplasty 
or a urethral sling procedure, both of which are open 
operations. Urethral resistance can also be increased by the 
periurethral injection of Teflon or collagen. Teflon has been 
used for fifteen years and does not have the permanent effect 
of increasing the urethral resistance. It has the unacceptable 
side effects in experimental animals of causing granulomas. 
Although clinically Teflon has been well tolerated, there have 
been reports of pulmonary granulomas in humans. The search for 
other injectable substances has resulted in the use of 
glutaraldehyde cross-linked bovine collagen which has been 
shown to increase urethral resistance. Unfortunately, 
experience has shown that collagen tends to break down over a 
period of months or years, resulting in a recurrence of 
incontinence . 

Currently, there is a search for an injectable substance 
with anatomic integrity which is well tolerated by the patient. 
Substances such an Ivalon sponge, cut into small pieces and 
suspended in saline, have been suggested as suitable 
substitutes. 

Bio-active glasses have been utilized as bone replacement 
materials in a variety of reconstructive surgical techniques. 



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These glasses have been shown to develop a strong bond with 
hard tissue due to a series of ion-exchange reactions between 
the implant surface and body fluids that result in the 
formation of a biologically active calcium phosphate film at 
the implant tissue interface [Hench et al., J. Biomed. Mater, 
Res, , Vol. 5, pp. 117-141 (1971), and Hench et al. , J. Biomed. 
Mater, Res. , Vol. 7, pp. 25-42 (1973)]. Bio-active glasses 
have also been shown to form firm bonds with soft tissue 
[Wilson et al., J. Biomed. Mater, Res. . Vol. 15, pp. 805-817 
(1981); Wilson and Merwin, J. Biomed. Mate r. Res,: Applied 
Biomaterials , Vol. 22, No. A2, pp. 159-177 (1988); and Wilson, 
Low et al., Biomaterials and Clinical App lications, ed. by 
Pizzoferrato et al, Elservier Science Publishers B.V. , 
Amsterdam (1987)]. 

Certain bio-active and bio-compatible glasses and glass- 
ceramics (i.e., those described in U.S. Patent Nos. 4,159,358; 
4,234,972; 4,103,002; 4,189,325; 4,171,544; 4,775,646 and 
4,851,046) have been shown to develop a unique, strongly 
adherent, chemical bond with hard-bone tissue due to the 
influence on hydroxyapatite of the biologically active calcium 
phosphate film generated in situ by ion-exchange reactions . 
between the glass or glass-ceramic surface and body fluids. 
This influence results in a strong fixation of the glass or 
glass-ceramic to the bone surface. Although as noted above, a 
variety of such glasses have been shown to bind to various soft 
tissue, it has been found that only a few of these glasses 
result in the formation of an exceptionally thin (i.e., no more 
than about 1-3 fibers thick), but adherent, collagen film which 
strongly adheres the glass to soft tissue without concomitant 
adverse side effects. 

Failure to observe soft tissue bonding of some glasses was 
a consequence of inappropriate preparation of material and 
selection of inappropriate tissue sites, e.g., muscle. When 
the glass implant is successfully immobilized in appropriate 
soft tissue during the experimental period and when proper 



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histological specimens are made, soft tissue adhesion to some 
glasses can be confirmed and evaluated. 

These particular glass compositions have also been found 
to advantageously become encapsulated with a thin (i,e., no 
more than about 1-3 fibers thick) layer of collagen after 
implantation. 

It is an object of the present invention to provide a 
novel injectable composition and method for the repair, 
augmentation, reconfiguration or replacement of hard bone or 
soft tissue anatomic structures which are not subject to the 
disadvantages associated with presently employed materials. 

SUMMARY OF THE INVENTION 
The above and other objects are realized by the present 
invention, which provides a pharmaceutically acceptable fluid 
composition capable of injection via a surgical needle into a 
human or non-human animal and particularly adapted for the 
repair, replacement, reconfiguration, reconstruction or 
augmentation of selected hard bone and/ or soft tissue anatomic 
structures therein comprising a homogeneous suspension in an 
aqueous solution of hyaluronic acid, salt or pharmaceutically 
acceptable derivative thereof (HA) having an average molecular 
weight of at least about 1 x 10 6 of at least one particulate 
bacteriostatic, bio-active and bio-compatible glass 
composition, the glass composition being one which: 

(a) forms a strong adherent bond comprising a thin layer 

of collagen at a glass /soft tissue interface upon 
injection in the animal; 

(b) forms a strong adherent bond comprising a layer of 
collagen no more than about 1-3 fibers thick; 

(c) becomes encapsulated after injection in the animal 
with a collagen layer attached by chemical and 
mechanical bonding to the bio-active surface; 

(d) does not result after injection in the animal in the 



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formation of excess scar tissue, giant cells or acute 

inflammatory cells; and 
(e) falls within Region E of the compositional boundary 

diagram of Fig. 4, 
wherein the particulate glass has a particle size preferably 
from 355/m to 100/xm; the aqueous solution has a concentration 
of HA and the ratio of particulate glass to the aqueous 
solution in the suspension is such that the fluid composition 
remains homogeneous under pressures encountered during the 
injection and, following injection, the HA is bioresorbed by 
the animal and the particulate glass remains at the selected 
anatomic structures and bonds uniformly throughout the 
particulate surfaces thereof with the hard bond and/ or soft 
tissue at the anatomic structures to provide anatomic integrity 
thereto without migration thereof or extrusion through adjacent 
tissue. 

The invention further provides a method for the repair, 
replacement, reconstruction, reconfiguration or augmentation of. 
a selected hard bone and/or soft tissue anatomic structure of a 
human or non-human animal comprising injecting into the 
anatomic structure the above-described composition. 

BRIEF DESCRIPTION OF THE DRAWINGS 
Fig. 1 graphically depicts the spreading rates of varying 

HA compositions according to the invention. 

Fig. 2 depicts a syringe and surgical needle system for 

delivery of the composition of the invention. 

Fig. 3 graphically depicts injection force as a function 

of syringe volume for a single HA composition, the ratios of 

bio-active glass particulate/ vehicle being between 0.32 and 

0.4. 

Fig. 4 is a ternary compositional boundary diagram of 
Si0 2 -CaO-Na 2 0 glasses. Region A bounds those compositions 
which are bone-bonding glass formers. Ceravital< R > which is 
known to bond to bone tissue, but not to soft tissue, is 



WO 91/17777 



PCT/US91/03596 



re- 
located within Region A. Region B comprises those compositions 
which are neither bone- nor soft-tissue bonding glass formers. 
Region C defines those compositions which form glasses that 
dissolve in vivo when implanted in the body. Region D defines 
bone-bonding non-glass formers. Region E defines the 
compositions within Region A which form glasses capable of 
bonding to bone and forming acceptable thin cellular collagen 
bonds with soft tissue. 

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 

The following terms have the meanings and definitions 
normally associated therewith by those skilled in the art, 
except as modified hereinbelow. 

The term "fluid" as used herein is intended to include any 
flowable and injectable liquid composition, including highly 
viscous compositions sometimes referred to as "pastes." 

"Hyaluronic acid, salt or other derivative thereof" (HA) 
is intended to include hyaluronic acid, as well as salts or 
other derivatives naturally present in the human or non-human 
animal (e.g., in the vitreous humor, synovial fluid, etc.). 
Herein, the acronym "HA" is employed to refer to hyaluronic 
acid, as well as suitable salts and/or derivatives thereof. 

"Pharmaceutically acceptable" is intended to include any 
material which is compatible with the other ingredients of the 
composition, which are not deleterious to the recipient 
thereof, have the intended function and are capable of 
administration to its recipient in the intended manner. 

The term, when used in connection with HA, is intended to 
include only those HA fractions which are sterile, non- 
pyrogenic, non-antigenic and non-inflammatory as those terms 
are normally and conventionally employed in the art. 

The compositions and formulations of the invention may be 
presented in "unit dosage form" which is intended to include 
all amounts, ratios, concentrations, etc., of the composition 
effective to achieve the desired result or condition. It will 



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be appreciated by those skilled in the art that dosages and 
dosage rates are adjusted according to the species of animal 
treated, magnitude of desired response and other factors 
routinely taken into consideration in establishing dose rates. 
They may be formulated by any of the methods described above or 
by any of the methods well known in the art of pharmacy for 
forming suspensions of solids in liquids. 

The term "surgical needle" includes any needle adapted for 
delivery of the fluid compositions of the invention after 
injection into a selected anatomical structure. Typical such 
needles are used in conjunction with syringes utilizing a 
plunger to pressurize and deliver the composition to the 
intended site. 

The term "anatomic structure" refers to any site or locus 
within the human or non-human animal, composed of hard bone 
and/or soft tissue, which requires repair, reconstruction, 
augmentation, replacement or reconfiguration to restore to 
transform it to a desired new configuration or state. 

Exemplary of such anatomic structures treatable according 
to the method of the invention include vocal cords, 
periurethral tissue, periureteral tissue, maxilla, mandible, 
temporomandibular joint, chin, zygomatic arch, nose, ear, tooth 
root canal, tooth pulp caps, dental restoration, defects in 
bone, vertebral spaces, articulating joints, and subcutaneous 
and intradermal soft tissues. 

The term "anatomic integrity" refers to the desired size, 
shape or configuration of a particular anatomic structure after 
bonding therewith of the particulate glass phase of the 
composition of the invention. 

The term "homogeneous" as used herein is intended to 
include all compositions (1) not subject to preferential 
extrusion of one or more o'f the components when injected into 
the patient or animal and (2) not subject to segregation of one 
or more of the components of the mixture when allowed to stand 
for long periods of time. 



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Generally, it has been found that bio-active and bio- 
compatible glasses having the following weight percent 
compositions give satisfactory results when utilized as the 
particulate glass component of the invention. 



Component 

sio 2 

CaO 
Na 2 0 
P 2 0 5 
CaFn 



B 2 0 3 



Weight Percentage 
40-54 
20-50 
10 - 35 

2-8 

0-25 

0-10 



The following compositions have been found to yield 
optimum results and are, therefore, preferred. 



Component 
Si0 2 
CaO 
Na 2 0 

p 2°5 



Weight Percentage 
45.0 
24.5 
24.5 
6.0 



Component 
Si0 2 
CaO 
CaF 2 
Na 2 0 
P 2 0 5 



Weight Percentage 
43.0 
14.0 
13.0 
24.0 
6.0 



Component 
Si0 2 
CaO 
Na 2 0 
P 2 0 5 
B 2 0 3 



Weight Percentage 
40.0 
24.5 
24.5 
6.0 
5.0 



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Component 
Si0 2 
CaO 



Weight Percentage 
52.0 



21.0 



Na 2 0 
P 2 °5 



21.0 



6.0 



It will be understood that although the invention is 
described herein as embodying glasses falling within Region E 
of the ternary diagram of Fig. 4, the glasses may also contain 
the additional components specified above in the indicated 
amounts, it will be understood that such glasses still may be 
described as falling within Region E of Fig. 4. 

The thin (1-3 fibers) collagen bond and capsule formed 
after implantation of the glass composition according to the 
invention do not thicken with time. The devices of the prior 
art usually fail because the included material and associated 
tissue response disappears with time as the material (for 
example, Teflon particles, hydroxyapatite particles, glass 
beads) is not bonded to and thus retained by the host tissues. 
Migration from the site removes the desired effect of tissue 
augmentation and provides additional hazard due to migration to 
other tissues with the potential for catastrophic embolism. 

The particulate glass is preferably prepared according to 
the following method: the raw materials are mixed in a Nalgene 
container on a ball mill for four hours. The mix is then 
melted in a platinum crucible at 1350°C and homogenized for 24 
hours. The molten glass is poured into distilled-deionized 
water to produce a glass frit, the frit is ground in a mortar 
and pestle and passed through ASTM sieves to produce the 
required particle size range. 

The primary variables affecting the rheology of the bio- 
active compositions of the invention and the ability to inject 
through typical 16-18 gauge needles are: maximum particle 



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size, range of particle sizes, ratio of the weight of glass 
particles to the weight of hyaluronic acid solution, and 
percentage of hyaluronic acid in solution. 

Each of these parameters may, of course, be varied to 
optimize the composition for a particular application . 

Particles larger than 45 mesh ASTM Standard (355/xm) cannot 
be injected through a 16 gauge needle without unduly decreasing 
the volume of glass powder in the paste by a significant 
amount. Since the objective is to deliver as large a quantity 
of particles per injection as possible, the practical upper 
limit in particle size is about 355/zm. 

Particles smaller than 100/na are subject to macrophage 
attack in vivo . Since the objective is to retain the maximum 
number of particles in the tissues per injection, this 
establishes the lower limit of particle size at about 100/xm. 

Selection of polymer, for the injectable composition 
requires meeting three criteria: (1) the polymer must be 
bioresorbable with no negative biological responses, i.e., it 
must be metabolized relatively quickly and with no deleterious 
effects; (2) the rheological properties must be such that a 
relatively small quantity when mixed with a large volume of 
glass particulate will create a solution with a paste-like 
consistency which can be extruded through a needle; and (3) the 
viscosity/ shear properties of the polymer must not lead to 
preferential extrusion or segregation of the polymer during 
injection. 

Hyaluronic acid, as well as its pharmaceutical^ 
acceptable salts and derivatives, meet each of the three 
criteria above. As reviewed by Balazs et al. [Proc. 5th Annual 
Conf. Biotechn. CMC Corp., pp. 1-8, 1988], the rate of removal 
of HA from the anterior chamber of the eye is only 1-2 days 
half-life and removal from blood is only 2-5 minutes half-life. 
The removal is via the liver endothelium where it is completely 
broken down chemically and eliminated [Frazer et al., Clin. 
Exp. Pharm. Phy s. , Vol. 11, pages 17-25, 1984]. 



WO 91/17777 PCT/US91/03596 



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Balazs and Denlinger [CIBA Foundation Symp. #143, pp. 265- 
280, 1989] state that the unique Theological properties of the 
hyaluronan molecule stem from its large molecular volume and 
from its extensive interactions with and entanglement of the 
molecular coils. In only a 0.02% solution, the HA molecules 
with a 2-4 million molecular weight per molecule have such a 
large volume that the molecules are touching and form a crowded 
network. For a 2% solution, the molecules are 100 times more 
crowded. However, since the network is not cross-linked, it is 
readily deformed by mechanical forces, such as a moving plunger 
in a syringe. Under low shear rates, e.g., slow-speed 
injection, the network shows high viscosity. Under rapid shear 
rates, the viscosity decreases. Decreasing the percentage of 
HA in solution decreases the viscosity and viscosity/ shear 
dependence • 

EXAMPLE 1 

The glass powders are mixed with HA molecular solutions in 
the range of 1%, 1.2%, 1.4%, 1.8% and 2%, and the spreading 
rates of the resultant pastes were tested. These experiments 
are summarized in Fig. 1. They show that for solutions up to 
and including 1.8% HA, the pastes continued to spread under 
pressure. The conclusion from this experiment is that HA gel 
viscosity increases linearly with concentration in solution. 
Since (1) the gel's seepage (preferential extrusion) through 
the paste decreases with increasing viscosity, (2) gel seepage 
must be avoided to ensure good quality injections, and (3) a 2% 
HA solution is still sufficiently pliable to allow easy 
manipulation, but minimizes seepage, a 2% HA solution is 
preferably used in the paste. 

EXAMPLE 2 



The optimal ratio of polymer to glass particulate to 



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achieve a paste capable of being injected through 16-20 gauge 
needles was determined as follows: 

A given quantity of glass particulates of 45-120 mesh were 
weighed and a 1% HA solution was added as required to produce 
ratios from 0.33 glass/HA to 1.6 glass/HA. The powder and 
polymer were mixed with a spatula using a stirring and 
spreading motion until homogeneity was achieved (approximately 
one minute) . The paste was loaded into the top of a large 
syringe and then injected into a smaller syringe with has a 16 
or 20 gauge needle or no needle. It was discovered that this 
method of loading eliminates air bubbles in the paste. The 
paste was injected through the needle using moderate speed and 
pressure, and the relative smoothness of the injected volume 
was noted by manual manipulation. Segregation of the polymer, 
which must be avoided, eliminated glass particles from the 
injected material which could be detected by feeling it, 
although microscopy was also used to verify the findings. 

The results of this test series are shown in Table 1 with 
the ratios passing through the (a) small syringe, (b) small 
syringe with a 20 gauge needle, and (c) small syringe with a 16 
gauge needle. With a ratio of 0.4 glass particulate/HA, the 
paste passed through both sizes of needle with no clogging. 
The optimal ratio within the given particle size range 
corresponds to 2.5 parts of HA to 1 part of glass particulate. 



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TABLE 1 

Parameter Variation and injection Results 



Glass /HA 


HA Volume 








Volume of 


Syringe Only 


(ml) 


Mesh 


Size 


Clog (ml) 


1.0 


0.5 


25 




45 


0.25 


1.0 


0.5 


25 




35 


0.30 


1.0 


0.5 


35 




45 


0.22 


1 . 0 


0.1 


35 




45 




1.0 


0.1 


45 




120 


— 


1.0 


0.5 


45 




120 




1.4 


0.5 


45 




120 


0.01 


1.6 


0.5 


45 




120 


0.14 


1.5 


0.5 


45 




120 


0 . 06 


1.375 


0.4 


45 




120 


0 • 04 


1.25 


0.4 


45 




120 




Glass/HA 


HA Volume 








Volume of 


Syringe Only 


(ml) 


Mesh Size 


Clog (ml) 


1.0 


0.1 


45 




120 




1.0 


0.5 


45 




120 


0.22 


1.0 


0.3 


80 




120 


0.13 


0.5 


0.3 


80 




120 


0.04 


0.4 


0.3 


80 




120 




0.4 


0.5 


80 




120 


0.02 


0.4 


0.4 


80 




120 




0.33 


0.5 


45 




120 


0.02 


Glass/HA 


HA Volume 








Volume of 


16 Gauge Needle 


(ml) 


Mesh Size 


Clog (ml) 


0.5 


0.5 


45 




120 




0.5 


0.3 


35 




120 




0.33 


0.5 


35 




120 




0.67 


0.5 


45 




120 


0.13 


0.40 


0.5 


45 




120 





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The relative roundness of the glass particles also affects 
the rheology of the paste and the optimal ratio of glass to HA. 
For particles with sharp corners, as produced by crushing of 
glass, the optimal ratio is 0.4, as determined above. With 
completely round particles, the ratio can be increased slightly 
when all other parameters are unchanged. The final optimal 
ratio, however, will be slightly less than 0.4. 

Rounding of the crushed glass sufficient to improve the 
rheology can be accomplished by milling dry without a milling 
medium for 48 hours and sieving off the finer particles. 

The configuration of the syringe used for the delivery of 
the injectable paste is also an important variable for 
optimizing the method of the invention. A design which 
minimizes the force needed for paste injection and thus 
maximizes the amount of glass in the paste and minimizes the 
seepage of HA during extrusion at clinical injection rates is 
given in Fig. 2. The critical design features are barrel and 
die L/D ratios, barrel/die diameter ratios and the die taper 
angle. 

Referring to Fig. 2, a syringe/needle assembly consists of 
barrel 12, plunger 14 and syringe tip 16. Preferred dimensions 
of the assembly for injecting optimum pastes according to the 
invention are as follows: The thickness represented by arrows 
(a) of the plunger cap 18 and grip flange 20 is 0.1 cm. The 
diameter of the plunger cap [arrow (b) ] is 1.414 cm. The 
diameter of the grip flange [arrow (c) ] is 1.714 cm. The 
length of the barrel [arrow (d) ] is 11.5 cm. The distance 
[arrow (e) ] between the plunger cap 18 and grip flange when 
fully depressed is 0.5 cm. The distance between the plunger 
cap 18 and the end of the barrel [arrow (f ) ] when fully 
depressed is 12.0 cm. 

The diameter [arrow (g) ] of the plunger is 0.614 cm and 
the inner diameter [arrow (h) ] of the barrel is 0.714 cm. The 
length of the taper of the proximal end of the barrel to the 
beginning of the syringe tip 16 [arrows (i)] is 0.166 cm. The 



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angle (a) between the tape wall at the end of barrel 12 and the 
longitudinal axis of the barrel 12 is 65°. The taper of the 
syringe tip 16 from the end of the barrel 12 is a standard Luer 
taper. The outer diameter of the proximal end of the syringe 
tip 16 is 0.155 cm- The length of the tapered syringe tip 16 
[arrow (j)] is 0.170 cm. 

EXAMPLE 3 

The ideal syringe volume is a compromise between ease of 
use and sufficient paste volume delivery. Since a total of 10- 
12 ml of the paste needs to be injected in at least three sites 
in clinical practice to treat urinary incontinence, a 3-4 ml 
syringe is desirable. Also, experiments show that the least 
force is needed to inject pastes when the syringe volume is 
about 4 ml (Fig. 3) . This is totally unexpected in view of the 
theoretical predictions for injectable mixtures. 

EXAMPLE 4 

Two bio-active glass compositions having the following 
composition were employed in this experiment: 

45S5 Composition 43S5 4F Composition 

45% Si0 2 43% Si0 2 

24.5% CaO 14% CaO 

24.5% Na 2 0 13% CaF 2 

6% P 2 O s 6% P 2 0 5 

The particle sizes ranged from 100-355/zm and were suspended in 
medical grade HA acid, so as to be injectable through a #16 
needle. An injection of 0.1 ml was made into the dome of the 
bladder in rabbits and subcutaneous injections of both 
suspensions and of the HA acid alone were made (six 
subcutaneous injections in each animal) . Two rabbits were 



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killed after each of 2, 4, 6, 8, 10 and 12 weeks. All 
experimental sites were examined microscopically, as were major 
internal organs. Samples of liver, kidney, lungs and lymph 
nodes were digested and analyzed by AAS for silicon from 
migrating particles. 

Particulate material was present in 67% of injection sites 
in the bladder overall. No difference in tissue response was 
seen between glass compositions. Soft tissue bonding to the 
particles' surface was seen at all time periods. There was 
persistent cellularity within the particulate mass at all time 
periods, although there was no inflammation in adjacent tissues 
and the urothelium was invariably normal. 

Subcutaneous sites which contained HA were completely 
normal at all time periods. The material could not be detected 
by normal histological techniques. There was no difference 
between glass compositions at any time. Many of the injections 
were in the subdermal muscle planes rather than subcutaneous 
tissues. Tissue response showed bonding of soft tissues at all 
time intervals, but with persistent cellularity throughout the 
experimental period. Particles toward the periphery of the 
mass had thin collagenous tissue around them and no macrophages 
at the interface and those in the center had macrophages, giant 
cells and some focal inflammation between them. There was no 
inflammatory infiltrate in surrounding tissues. In some cases, 
the central part of the lesion was infarcted, although the 
peripheral particles were bonded in place. 

Histological examination of liver, lungs, lymph nodes and 
kidneys revealed no particles nor any toxicological effect. 
Chemical analysis showed no increase of silicon in tissues. 

In this rabbit model, the material frequently came to rest 
in muscle rather than fibrous connective tissue and the 
quantity injected was greater than is required clinically. The 
continuous movement of the host tissues produced significant 
cellularity inside the lesion due to abrasion of the ingrowing 
tissues. The peripheral particles were invariably bonded in 



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place without such cellularity and there was no effect on other 
tissues whether local or distant. The ability of HA to provide 
an injectable vehicle which is completely metabolized within 
the first two weeks was confirmed. 

Overall, eight out of twelve bladder sites were identified 
and retrieved at autopsy. The particles were present in the 
bladder wall between muscle fibers underlying the urothelium. 
They were surrounded by collagen fibers and cellular connective 
tissue at all times up to twelve weeks. There was no 
inflammation around the site and the overlying urothelium was 
normal. This tissue response is as expected in a moving muscle 
bed; the particles are immobilized, but abrasion of the tissues 
occurs with every expansion and contraction of the bladder 
wall. No difference was seen between 45S5 and 43S5 4F 
injections. In cases where the particulate material was not 
found, it was assumed that it was either retained in the 
syringe or injected through the bladder wall into the lumen. 

No change attributable to the materials was seen in liver, 
kidney, lung or bronchus in any animal at any time. Retrieval 
rate of drainage lymph nodes was very low; the few which were 
found were normal. It is assumed that the fact that drainage 
lymph nodes were not affected made them difficult to detect. 
Chemical analyses of these soft tissues showed no increase of 
silicon in tissues. 

HA injected sites were completely normal at all time 
periods. The tissue response to the glass materials was 
evaluated using the following criteria: 

1. Bonding of collagen fibers to the surface of 
particles. 

2. Presence of phagocytic cells at the interface. 

3. State of the tissue surrounding the mass, which is 
presumably more easily stabilized. 

4. State of the tissue in the center of the mass, which 
is presumably more prone to movement and is likely to 
take longer to stabilize. 



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5. Cellular response in adjacent tissues. 

The tissue response was variable. Soft tissue bonding was 
seen from four weeks, but phagocytes were present at all time 
intervals, although reducing in numbers throughout the 
experimental period. The outside of the mass was generally 
relatively acellular stable connective tissue, the inside was 
often more cellular and the fibers more fragile. Some masses 
had foci of degenerative change centrally. These effects are 
due to mechanical abrasion of the ingrowing collagen fibers and 
the new capillaries by the glass particles. There was no 
inflammation or infiltration of adjacent tissues. No 
difference was seen between 45S5 and 43S5 4F bio-active glass 
sites. 

In this model, effects due to movement in the tissues must 
be separated from those due to the material. The combination 
of HA and glass particulates could be injected. In the 
tissues, the HA produced no detectable effect, being removed 
without trace as predicted. The glass particulates were bonded 
to the collagen fibers of the connective tissue and were 
effectively retained in tissue up to twelve weeks. The 
presence of persistent cellularity, phagocytosis and some 
necrosis is attributable to mechanical damage in tissues. The 
amounts of injection which are recommended for clinical use, 
being much smaller, will not cause this problem. 



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CLAIMS 

1. A pharmaceutical^ acceptable fluid composition capable of 
injection via a surgical needle into a human or non-human 
animal and particularly adapted for the repair, replacement, 
reconfiguration, reconstruction or augmentation of selected 
hard bone and/ or soft tissue anatomic structures therein 
comprising a homogeneous suspension in an aqueous solution of 
hyaluronic acid, salt or pharmaceutically acceptable derivative 
thereof having an average molecular weight of at least about 1 
x 10 6 , of at least one particulate bacteriostatic, bio-active 
and bio-compatible glass composition, said glass composition 
being one which: 

a. forms a strong adherent bond at a glass/hard bone 
tissue interface upon injection in said animal; 

b. forms a strong adherent bond at a glass /soft tissue 
interface upon infection in said animal ; 

c. becomes encapsulated after injection in said animal 
with a thin collagen layer; 

d. does not result after injection in said animal in the 
formation of excess scar tissue, giant cells or acute 
inflammatory cells; and 

e. falls within Region E of the compositional boundary 
diagram of Fig. 4, 

wherein said particulate glass has a particle size; said 
aqueous solution has a concentration of said hyaluronic acid, 
salt or derivative thereof and the ratio of particulate glass 
to said aqueous solution in said suspension is such that said 
fluid composition remains homogeneous under pressures 
encountered during said injection and, following injection, 
said hyaluronic acid, salt or derivative thereof is bioresorbed 
by said animal and said particulate glass remains at said 
selected anatomic structures and bonds uniformly throughout the 
particulate surfaces thereof with said hard bone and/or soft 
tissue at said anatomic structures to provide anatomic 



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integrity thereto without migration thereof or extrusion 
through adjacent tissue, 

2. A composition according to claim 1, wherein said aqueous 
solution contains hyaluronic acid. 

3. A composition according to claim 1, wherein said aqueous 
solution contains sodium hyaluronate. 

4. A composition according to claim 1, wherein said 
bacteriostatic, bio-active and bio-compatible glass has the 
following weight percentage composition: 



Component Weight Percentage 

Si0 2 40-54 

CaO 20-50 

Na 2 0 10 - 35 

P 2 O s 2-8 

CaF 2 0-25 

B 2 0 3 0-10. 

5. A composition according to claim 4, wherein said 

bacteriostatic, bio-active and bio-compatible glass has the 

following weight percentage composition: 

Component Weight Percentage 

Si0 2 45.0 

CaO 24.5 

Na 2 0 24.5 

P 2 0 5 6.0. 



6. A composition according to claim 4, wherein said 
bacteriostatic, bip-active and bio-compatible glass has the 
following weight percentage composition: 



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Component Weight P ercentage 
Si0 2 43.0 
Na 2 0 24*0 
CaO 14 * 0 

CaF 2 13.0 
P 2 0 5 6.0. 

7. A composition according to claim 4, wherein said 
bacteriostatic, bio-active and bio-compatible glass has the 
following weight percentage composition: 

Component Weight Pe rcentage 
Si0 2 40.0 
CaO 24.5 
Na 2 0 24.5 
P 2 0 5 6.0 
B 2 0 3 5.0. 

8. A composition according to claim 4, wherein said 
bacteriostatic, bio-active and bio-compatible glass has the 
following weight percentage composition: 

Composition Weight Pe rcentage 
Si0 2 52.0 
CaO 21.0 
Na 2 0 21.0 
P 2 0 5 6.0. 

9. A method for the repair, replacement, reconstruction, 
reconfiguration or augmentation of a selected hard bone and/or 
soft tissue anatomic structure of a human or non-human animal, 
comprising the step of injecting into said anatomic structure a 
composition which itself comprises a homogeneous suspension, in 
an aqueous solution of hyaluronic acid, salt or 
pharmaceutical ly acceptable derivative thereof, of at least one 



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biocompatible glass composition, wherein: 

a. said glass composition is in the form of particles; 

b. the ratio of glass particles to said aqueous solution 
is such that the suspension remains homogeneous under 
pressures normally encountered during injection; and 

c. following injection, said hyaluronic acid, salt or 
pharmaceutical^ acceptable derivative thereof is 
bioresorbed by said animal, and said glass particles 
remain at said anatomic structure and bond therewith 
to provide anatomic integrity thereto. 

16. The method of claim 9 wherein the sizes of said particles 
are within the range 100-355 pm. 

17. The method of claim 9 wherein the bioactive glass 
composition falls within Region E of the compositional boundary 
diagram of Fig. 4. 

18. The method of claim 9 wherein said anatomic structure 
comprises periurethral tissue. 

19. The method of claim 9 wherein said anatomic structure 
comprises periureteral tissue. 

20. The method of claim 9 wherein said anatomic structure 
comprises maxillofacial tissue. 

21. The method of claim 9 wherein said anatomic structure 
comprises mandibular tissue. 

22. The method of claim 9 wherein said anatomic structure is 
tooth root canal or pulp cap. 

23. The method of claim 9 wherein said anatomic structure is 
the vocal cords. 



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24. The method of claim 9 wherein said anatomic structure is 
defective bone. 

25. The method of claim 9 wherein said anatomic structure is a 
vertebral space. 

26. The method of claim 9 wherein said anatomic structure is 
an articulating joint. 

27. The method of claim 9 wherein said anatomic structure 
includes subcutaneous or intradermal soft tissue. 



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Figure 1 



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^AavJy Soviet . 



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Floured: Injection Force vs. syringe volumes for three Bio- 
glass /Hyalur on ratios. Ratio 1 = 0.32,. ratio 2 = 0.36, ratio 
3 = 0.40. 



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Figure 4 Compositional Diagram showing soft tissue bonding 
area (E) within the bone bonding area (A) . 



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