PRO-STIM
®
Injectable Inductive Graft
T ECHNIC A L MONO GR A PH
PRO-STIM®
Injectable Inductive Graft
TECHNICAL MONOGRAPH
4
Clinical Benefits
5
Self-Forming Porous Scaffold
7
Osteoinductive Potential
8
Healing with PRO-STIM® Injectable Graft Compared to
Autograft in a Canine Critical Size Defect Model
13
Conclusion
14
References
Appendix
Headline
Contents
Headline
Proper surgical procedures and techniques are the responsibility of the medical professional.
The following guidelines are furnished for information purposes only as techniques used by the
design surgeons. Each surgeon must evaluate the appropriateness of the procedures based
on his or her personal medical training and experience. Prior to use of the system, the surgeon
should refer to the product package insert for complete warnings, precautions, indications,
contraindications and adverse effects. Package inserts are also available by contacting Wright
Medical Technology, Inc.
Please contact your local Wright representative for product availability.
PRO-STIM®
Injectable Inductive Bone Graft Substitute
3
PRO-STIM®
Injectable Inductive Bone Graft
Substitute
Hardening. Resorbable. Osteoinductive. Regenerative.
»» Accelerated Healing*
- Faster healing than autograft at 13 weeks in canine model
PRO-STIM® Injectable Inductive Graft is a resorbable, hardening, osteoinductive bone graft substitute. Built on the PRO-DENSE® material
platform as a combination of calcium sulfate and calcium phosphate,
PRO-STIM® graft adds demineralized bone matrix (DBM) for
osteoinductive factors to speed the healing and remodeling process.
Autograft remains the “gold standard” for many surgeons because
it includes all three desired features of a bone graft: scaffolding for
osteoconduction, proteins for osteoinduction, and stem cells for
osteogenesis. Additionally, it is
autologous thus eliminating concerns of
an immune or foreign body response.1
Donor morbidity and multiple
complications at the site of autograft
harvest, however, remain a challenge.2,3
DBM
While many materials have been shown
CaSO4
to perform equivalent to autograft,
two products to date- PRO-DENSE®
graft and now PRO-STIM® graft- have
CaPO4
demonstrated superiority to autograft
in pre-clinical testing.4,5
In previous testing in a metaphyseal
canine defect model, PRO-DENSE® graft
demonstrated an ability to regenerate denser and stronger new bone
faster than autograft at 13 weeks. Additionally, the new bone regenerate
maintained increased density for a period before remodeling (by 26 weeks).
As summarized in Section III PRO-STIM® graft demonstrated accelerated
healing and earlier initiation of remodeling in treated sites compared to
autograft in the same canine model.
*Canine proximal humerus model: Accelerated healing compared to autograft –Compared to autograft, PRO-STIM® Graft showed
accelerated new bone formation at 13 and 26 weeks. This was evident by the slightly higher average stiffness, the greater amount of
average new bone formation, and statistically significantly greater compressive strength shown for PRO-STIM® Graft treated defects. By
comparing the 26-week clinical and contact radiographs and gross cross-sectional images and histological images, there appeared to be
little to no apparent difference between defects f illed with either PRO-STIM® Graft or autograft. Comparison of percentage of new bone,
compressive strength, and modulus of elasticity showed no statistically significant differences between the materials at 26 weeks. It is
unknown how results from the canine model compare with clinical results in humans. Data on f ile at Wright.
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PRO-STIM®
Injectable Inductive Bone Graft Substitute
Self-Forming Porous Scaffold
Tri-phasic Resorption Reveals an Interconnected, Porous Scaffold5
The physical progression of the resorption process is illustrated in
FIGURE 1, which shows SEM images of cross sections through embedded
PRO-STIM® graft after zero, two, four, eight, and twelve days of
accelerated in vitro dissolution which has been estimated to occur about
six times faster than in vivo. The darker region on the outer edge of the
pellet represents the area in which calcium sulfate has largely dissolved,
leaving a porous scaffold of brushite (bright white) and DBM particles
(very dark spots).
Time – 0 Days
Time – 2 Days
Time – 4 Days
Time – 8 Days
FIGURE 1 | In vitro accelerated
dissolution at 37°C in water (Image
analysis via SEM) (Approximately six
times faster than in vivo canine model).
Time – 12 Days (approx. 72 days in vivo)
PRO-STIM®
Injectable Inductive Bone Graft Substitute
5
Time – 0 Days
Time – 2 Days
Time – 4 Days
Time – 7 Days (approx. 42 days in vivo)
FIGURE 2 | In vitro accelerated dissolution at 37°C in water (Image analysis via SEM)
(Approximately six times faster than in vivo canine model).
In FIGURE 2, the SEM images of the pellets show that much of the size of
the PRO-STIM® pellet is maintained at early timepoints. Even at 4 days,
the calcium sulfate has started to dissolve revealing the porous calcium
phosphate structure containing DBM particles. By 7 days, a large portion
of the remaining pellet is the porous structure of calcium phosphate
and DBM (large white particles). By contrast, pure calcium sulfate is
completely resorbed by 10 days in this same experiment.
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PRO-STIM®
Injectable Inductive Bone Graft Substitute
Osteoinductive Potential
Osteoinductivity of PRO-STIM® Injectable Graft in an Athymic
Nude Rat Model5
Objective
The objective of this study was to evaluate the osteoinductivity of
PRO-STIM® graft in an athymic rat muscle pouch model.
Materials and Methods
Incisions were made through the latissimus dorsi and gluteus superficialis
muscles on each side of the midline of an athymic nude rat model. Two
pouches were created on each side using blunt dissection. PRO-STIM®
graft was mixed according to instructions. After aggressively mixing for
30 seconds, samples were manually rolled into small, elliptical balls. The
graft specimens were gently implanted into the muscle pouches after
they had hardened. Each rat received four implants. After implantation,
the muscle incisions were closed. The implants were harvested at 28 days.
Specimens were decalcified for ten days, embedded in paraffin, and
stained with hematoxylin and eosin (H&E).
FIGURE 3 | Histology image of PRO-STIM®
graft within athymic nude rat muscle pouch
(H&E original mag 20X).
Results
The PRO-STIM® graft prepared with human DBM induced measurable
new bone growth as shown in FIGURE 3.
Conclusion
PRO-STIM® graft was shown to be osteoinductive when implanted in an
athymic nude rat muscle pouch model.
PRO-STIM®
Injectable Inductive Bone Graft Substitute
7
Healing with PRO-STIM® Injectable Graft
Compared to Autograft in a Canine Critical Size
Defect Model5
Objective
The primary objective of the studies was to evaluate the in vivo
performance, including at early timepoints, of PRO-STIM® graft in a
canine proximal humerus critical size metaphyseal defect model. Defects
were created, filled, harvested, and evaluated histologically at 2, 3, 4, 6,
8, 10, 13, and 26 weeks. A second objective was to compare healing in
the defects treated with PRO-STIM® graft and autograft by compiling
data from studies previously conducted in the same model, at the same
institute, and by the same research team. Compressive strength of healed
defects was also assessed at 13 and 26 weeks.
Materials and Methods
Cylindrical defects (13mm diameter x 50mm) were created bilaterally
in the proximal humerus of adult male, hound-type dogs. Immediately
prior to implantation, PRO-STIM® graft was prepared according to
instructions provided with each kit. One defect per dog was filled with
PRO-STIM® graft prepared with canine demineralized bone matrix (DBM)
and the other defect was filled with autograft. Dogs were sacrificed
at 2, 3, 4, 8 and 10 weeks (n=1 per timepoint); 6 weeks (n=3); and 13
and 26 weeks (n=5 per timepoint). Following sacrifice, the proximal
humerus was harvested and the length of bone with the implant site
was cut into sections. Contact radiographs were taken of sections of the
defect. Specimens were processed and embedded in PMMA and slides
were stained with basic fuschin and toluidine blue. The percentage of
new bone was measured from histology images using a point counting
method. Previous data from comparable defects treated with autograft
were compared. From specimens harvested at 13 and 26 weeks, samples
8mm diameter x 20mm long were cored from the defect regions and
loaded under compression until failure.
Results
Resorption of calcium sulfate, evident as darkening of the implant, starts
at the outer rim of the implant and occurs within two weeks (FIGURE
4). Similar to the progression seen in vitro, the calcium phosphate and
DBM initially remain within the resorbing area until surrounded and/
or replaced by bone. Resorption and replacement with mature bone
progresses quickly and the bulk of material, particularly the calcium
sulfate and calcium phosphate, is gone by 8 weeks (FIGURE 4). In the
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PRO-STIM®
Injectable Inductive Bone Graft Substitute
autograft implant sites, although a notable amount of new bone is
present in the defect sites as early as 2 weeks, the new bone is markedly
immature as indicated by thin, small spicules of young bone and remains
largely immature past 8 weeks.
A. PRO-STIM® GRAFT
2 weeks
3 weeks
4 weeks
6 weeks
8 weeks
10 weeks
13 weeks
26 weeks
2 weeks
3 weeks
4 weeks
6 weeks
8 weeks
10 weeks
13 weeks
26 weeks
B. AUTOGRAFT
FIGURE 4 | (a) In contact radiographs of a cross-section of PRO-STIM® implant sites, resorption is evident by 2 weeks. By 6 weeks, the bulk
of the material is gone and significant bone growth is evident. By 26 weeks, the entire defect site is filled with mature bone resembling
adjacent native bone. (b) While new bone growth is evident as early as 2 weeks in the autograft implant sites, the thin bone appears very
immature, without the density representative of more mature bone. This immature bone largely persists beyond 8 weeks.
PRO-STIM®
Injectable Inductive Bone Graft Substitute
9
Native Bone
Immature Bone
Resorption Front
PRO-STIM® Implant
FIGURE 5 | At 3 weeks following implantation of PRO-STIM® graft, several regions of
healing are distinct. Within the original defect site and immediately adjacent to native
bone, there are immature, thin spicules of new bone. Immediately within the new
bone is the resorption front region in which much of the calcium sulfate and calcium
phosphate material has resorbed, revealing DBM. The area within the resorption region
contains PRO-STIM® implant material that is primarily intact.
Histological images of PRO-STIM® implant sites at each timepoint show
distinct regions of implant resorption and healing (FIGURE 5) that progress
inward over time.
Histology images of PRO-STIM® graft and autograft implant sites over
time (FIGURE 6) show progression of material resorption and new
bone growth consistent with views of the contact radiographs. As
early as 2 weeks, new bone growth visibly maintains tight contact with
the resorption front of the implant material. Consistent with contact
radiographs, by 8 weeks, the bolus of implant is gone and the defect site
has filled with new bone.
This rate of resorption and healing is consistent with the presence
of remodeled mature cancellous bone in the defect site that is
indistinguishable from surrounding bone at 26 weeks (FIGURE 6).
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PRO-STIM®
Injectable Inductive Bone Graft Substitute
In the autograft sites, new bone is evident at 2 weeks although the
bone is thin and spicule-like representing very immature bone which has
little strength due to few, disorganized collagen fibers. This immature
bone structure is maintained until 13 weeks at which time the bone has
remodeled to more mature bone resembling surrounding bone.
A. PRO-STIM® GRAFT
2 weeks
3 weeks
4 weeks
6 weeks†
8 weeks
10 weeks
13 weeks
26 weeks
2 weeks
3 weeks
4 weeks
6 weeks
8 weeks
10 weeks
13 weeks
26 weeks
B. AUTOGRAFT
FIGURE 6 | (a) Consistent with contact radiographs, at 2 weeks, resorption of PRO-STIM® graft with some evidence of new bone growth at
the periphery of the implant is observed. Continued material resorption and notable new bone growth is apparent at 3 weeks and continues
to progress at a fast rate with the bolus of the implant predominantly gone and replaced with mature bone at 8 weeks. †[NOTE: The hole in
6-wk PRO-STIM® histology image is due to wash-out during post-explantation processing.] (b) In the autograft sites, new bone observed at
2 weeks is very immature, indicated by thin, small spicules of young bone; remodeling into more mature bone does not occur until after 10
weeks. (Basic fuschin and toluidine blue, 10X)
PRO-STIM®
Injectable Inductive Bone Graft Substitute
11
Area Fraction of New Bone
40
PRO-STIM® Graft
35
Autograft
Percent
30
25
20
15
Compressive
Strength (MPa)
13 Weeks
3
Compressive
Strength (MPa)
10
3
5
0
Normal Bone
26 Weeks
2
5
1
10
15
20
25
Normal
30 Bone
Time (Weeks)
FIGURE07 | A plot of percentage new bone over time in defect sites filled with PRO-STIM®
graft vs. autograft indicates accelerated healing, increased
volume in new bone formed,
Autograft
PRO-STIM® Graft
and remoldeling to normal at 13 weeks with PRO-STIM® implants compared to autograft.
New Bone Regenerate
2
Normal
Bone
1
Autograft
0
PRO-STIM®
13 Weeks
Autograft
PRO-STIM®
26 Weeks
FIGURE 8 | Compressive strength of the new bone regenerate at 13 and 26 weeks .
*Friedman Test, p=0.046
Graphical presentation of new bone growth over time (FIGURE 7)
demonstrates acceleration of healing and earlier initiation of remodeling
in PRO-STIM® implant sites compared to autograft sites. At their
respective peaks of healing, PRO-STIM® graft was associated with greater
bone volume than autograft.
Mechanical test results indicated compressive strength comparable to
that of normal bone in both PRO-STIM® graft and autograft-treated sites
at both 13 and 26 weeks (FIGURE 8).
At 13 weeks, compressive strength of the PRO-STIM® specimens was
comparable to normal bone and was significantly greater than that of
autograft specimens (p=0.046) (FIGURE 8). The lower strength of the
autograft sites may be due to decreased maturity of the new bone. By
26 weeks, the compressive strength of both the PRO-STIM® graft and
autograft-treated sites was comparable to new bone.
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PRO-STIM®
Injectable Inductive Bone Graft Substitute
Conclusion
PRO-STIM® graft has demonstrated accelerated healing, increased volume
in new bone formed, and remodeling to normal bone at 13 weeks vs.
autograft in the canine critical sized defect model.
PRO-DENSE® and PRO-STIM® grafts have been shown to be superior to
autograft in the canine proximal humerus model at the 13 and 26 week
time points.5,6
PRO-STIM® graft demonstrates a resorption pattern that reveals the
osteoinductive DBM over a defined period of time. The osteoinductivity
was clearly demonstrated in the athymic nude rat muscle pouch model in
which the composite graft was implanted and new bone formation was
evident.
PRO-STIM® graft has demonstrated accelerated healing, increased volume
in new bone formed, and remodeling to normal at 13 weeks vs. autograft
in the canine critical sized defect model.
PRO-STIM®
Injectable Inductive Bone Graft Substitute
13
References
1. Giannoudis PV, Dinopoulos H, Tsiridis E. Bone substitutes: an update.
Injury. 2005 Nov;36 Suppl 3:S20-7.
2. Younger EM, Chapman MW. Morbidity at bone graft donor sites. J
Orthop Trauma. 1989;3(3):192-5.
3. Fowler BL, Dall BE, Rowe DE. Complications associated with harvesting
autogenous iliac bone graft. Am J Orthop (Belle Mead NJ). 1995
Dec;24(12):895-903.
4. Turner TM, Urban RM, Hall DJ, Cheema N, Lim TH. Restoration of
large bone defects using a hard-setting, injectable putty containing
demineralized bone particles compared to cancellous autograft bone.
Orthopedics. 2003 May;26(5 Suppl):s561-5.
5. PRO-STIM® Graft Data on file at Wright Medical Technology.
6.Urban RM, Turner TM, Hall DJ, Inoue N, Gitelis S. Increased bone
formation using calcium sulfate-calcium phosphate composite graft.
Clin Orthop Relat Res. 2007 Jun;459:110-7.
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PRO-STIM®
Injectable Inductive Bone Graft Substitute
Sizing and
Ordering Information
Product Name
Part Number
PRO-STIM® EXTREMITY 4CC
86SR-0404
PRO-STIM® 10CC
86SR-0410
PRO-STIM® 20CC
86SR-0420
PRO-STIM® CORE DECOMPRESSION KIT*86SR-CK15
*Contains all necessary instruments for a
standard core decompression technique.
PRO-STIM®
Injectable Inductive Bone Graft Substitute
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010536A_30-June-2014
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PRO-STIM®
Injectable Inductive Bone Graft Substitute