Indications
Osmotic tissue expanders are indicated for the facilitation
of normal growth of orbital soft tissues and bone to achieve
proximate facial symmetry in congenital anophthalmos and microphthalmos.
Description
Osmotic tissue expanders are co-polymer based devices intended
to expand physiological tissue space. The material is a Methylmethacrylate
and N-Vinylpyrrolidone polymer. The expansion is a result
of osmotic swelling due to the absorption of fluid from the
surrounding tissues.
Orbit Expanders - The sphere configuration is used for orbit
expansion.
Socket Expanders - The hemisphere configuration is used for
expansion of the soft tissues of the eyelids.
| |
Start Vol |
Start Diam |
End Vol |
End Diam1 |
| Hemisphere |
0.13±0.02ml |
8.0±0.1 mm |
0.9±0.1ml |
14.0±0.5mm |
| 2ml Sphere |
0.27±0.03ml |
8.0±0.2 mm |
2.0±0.2ml |
15.5±0.5mm |
| 3ml Sphere |
0.27±0.03ml |
8.0±0.2 mm |
3.0±0.2ml |
18.0±0.5mm |
| 4ml Sphere |
0.43±0.03ml |
9.0±0.2 mm |
4.0±0.2ml |
19.7±0.5mm |
Contraindications
The use of the orbit expander is contraindicated in the presence
of a microphthalmic eye with useful vision.
Precautions
The expander devices operate by the osmotic absorption of
fluid. The devices must remain separate from body fluids and
irrigating solutions prior to use.
Care must be taken when explanting the device because the
material becomes soft and more fragile when fully hydrated.
Rough or excessive handling may result in fragmentation of
the hydrogel material following expansion. Any fragments that
may have separated from the device during explanation should
be removed.
Warnings
The clinical effect of X-ray on the implanted device has
not been determined. MRI is recommended.
Adverse Events
The clinical data on these devices consists of two published
papers and an ongoing clinical study. Complications reported
in the literature for the orbit expanders consist of infection,
insufficient closure and the use of a sphere that is too large.
The complication reported in the literature for the socket
expander is the spontaneous expulsion due to insufficient
closure.
Clinical Results
The published clinical data to date reports on the implantation
of a total of twelve socket expanders and two orbit expanders.
The following table represents the before and after palpebral
fissure expansion measured in millimeters for the patients
receiving socket expanders.
| Patient |
Age
Mos. |
Expansion Days |
Before OD |
After OD |
Before OS |
After OS |
| 1 |
6 |
30 |
8 |
20 |
9 |
20 |
| 2 |
11 |
24 |
|
|
9 |
24 |
| 3 |
5 |
24 |
10 |
22 |
|
|
| 4 |
7 |
30 |
8 |
20 |
9 |
20 |
| 5 |
11 |
60 |
10 |
17 |
21 |
23 |
| 6 |
4 |
60 |
10 |
15 |
18 |
20 |
| 7 |
3 |
60 |
9 |
12 |
19 |
19 |
Two cases received the orbit expanders in addition to the
socket expanders. There was no reported increase in palpebral
fissure with the incremental use of the orbit expander in
these cases. The following table demonstrates the time frame
and final volumes of the orbit expanders. The volume was determined
by CT-scan 150 and 40 days after implantation.
| Patient |
Expansion Time |
Volume Before |
Volume at Scan |
| 2 OS |
150 days |
0.42 ml |
4.5 ml |
| 3 OD |
40 days |
0.44 ml |
4.0 ml |
Instructions for Use
Both the orbit expanders(spheres) and socket expanders (hemispheres)
are packaged sterile and non-pyrogenic for SINGLE USE ONLY.
The implants are double wrapped in a chevron type peel pouch
and should remain secured in this pouch until the implant
site has been prepared to accept the device.
Orbit Expansion
The implant site for the sphere should be prepared by spreading
the soft tissue with surgical scissors to establish a location
deep within the orbit. A two-layer closure with interrupted
absorbable sutures will help to minimize the potential for
extrusion during the expansion phase. A temporal incision
may be used if the conditions permit the ability to work the
implant around the orbital rim and back into the deep orbit.
The implants are sized for progressive use. The procedure
can be repeated with consecutively larger sized spheres based
on the response of the tissue as determined by the physician.
For example, the 2ml sphere may be removed and replaced with
a 3ml or 4ml sphere as needed. Final closure should consist
of a temporary tarsorraphy with non-absorbing suture material
and use of a conformer as needed. Use of perioperative antibiotics
is recommended.
Socket Expansion
The hemispherical expander is intended to expand the lid
fissure. The expander should be placed with the convex side
facing anteriorly. The device should be secured directly to
connective tissue. The suture placed through the fixation
hole must be tied loosely in order to compensate for expansion
of the device. When an appropriate volume is obtained, the
final expander should be replaced with a permanent orbital
implant and prosthetic shell.
References
Wiese, KG, et al. Treatment of congenital anophthalmos with
self inflating polymer expanders: a new method. Journal of
Cranio-Maxillofacial Surgery (1999) 27:72-76
Bacskulin, A, et al. New osmotically active hydrogel expander
for enlargement of he contracted anophthalmic socket. Graefe's
Arch Clin Exp Ophthalmol (2000) 238:25-27
DO NOT RESTERILIZE.
CAUTION: Federal Law restricts the sales of this device
to sales or upon order of a licensed physician.
|
