Prosthetic/Orthotic Management After
Recent Hemipelvectomy for a
Myelomeningocele Patient
David F. Moretto, BS, CP
Jean L. Minkel, MS, PT
Mary D. Cardi, MS, PT
Introduction
Spina bifida is one of the most common developmental anomalies of the nervous system (1). Myelomeningocele, a subgroup of
spina bifida cystica, is a failure of the vertebrae to fuse, allowing a distension of the
spinal cord and nerve roots into a fluid-filled
sac formed by the dura and arachnoid (2,3).
Several associated complications include hydrocephalus, paraplegia, incontinence and
loss of sensation leading to pressure sores,
burns, etc. if routine skin care is not followed.
Following is a case study of a young man
with myclomeningocele who, as a result of
chronic osteomyelitis, had a right hemipelvectomy amputation. The prosthetic/orthotic seating device designed at Helen Hayes
Hospital's Prosthetic and Orthotic Department in the Center for Rehabilitation Technology provided a suitable weightbearing
surface for the residual limb as well as symmetrical weight distribution. Such a device is
applicable to many non-ambulatory, nonsensate patients who have had an amputation as a result of osteomyelitis, regardless of
diagnosis.
Patient Background
The patient was a 21-year-old male, 5'2", 140
lbs, who had a medical history of spina bifida
myelomeningocele (L3,4 level), hydrocephalus and a recent right hemipelvectomy amputation (August 1988) due to chronic osteomyclitis. The patient has had multiple orthopedic and plastic surgeries (35), exhibits
both a functional and structural scoliosis and
has a large adherent scar located over the
lumbar spine (see Figure 1
).
Voluntary movement was present in both
upper extremities, through his trunk and left
hip flexors. The patient wore a condom catheter for urinary collection in addition to intermittent catheterization. Functionally, the
patient was unable to maintain a sitting posture without bilateral upper extremity support for balance. Prior to admission, he was
positioned in a manual wheelchair with removable lateral trunk supports and sat on a
Roho cushion. He was independent in
wheelchair mobility.
The patient was admitted to Helen Hayes
Hospital's Center for Rehabilitation Technology to evaluate and provide necessary postural
support for wheelchair seating and mobility.
Objectives and Considerations
for Sealing Device Design
The goal was to provide a seating device
that:
- accommodated for right hemipelvectomy amputation.
- provided symmetrical pressure distribution so tissue over the remaining ischial tuberosity would not risk breakdown.
- accommodated for adherent scar area
on lumbar spine.
- allowed the patient to sit upright all day
with free use of both upper extremities.
- allowed independent donning/doffing
by the patient.
- was mobile with the patient to provide
support regardless of sitting base.
- was lightweight for pressure relief and
independence in transfers.
Initial attempts were made with commercial wheelchair trunk supports and cushions
to reduce left ischial pressures and improve
spinal alignment. Postural and functional
evaluations and seat cushion pressure interface measurements (described below)
proved these interventions inadequate. A
more customized molded design was necessary.
Design Description
After a thorough physical and functional
evaluation, a modified hemipelvectomy
socket design that would be used as a prototype device, was chosen. This socket design
would provide the needed upward oblique
pressure on the abdominal viscera, which is
tolerable to the patient, and provide lateral
support to the amputated side while carefully incorporating flexibility and freedom of
movement (4) (see Figure 2
).
To obtain an impression, the patient was
positioned prone on a treatment table with
his left lower extremity supported over the
edge in a flexed position (see Figure 3a
, and Figure 3b
).
Moistened plaster splints were placed on the
edge of the casting table prior to positioning
to obtain an anterior impression without
having to reposition the patient on his back.
Plaster splints were then placed over the patient's back and right residual limb while incorporating his left buttock and thigh. After
the posterior shell hardened, this section was
easily separated from the anterior section
(due to standard prior application of petroleum jelly).
The negative mold was then filled, and
traditional hemipelvectomy modifications
were performed with special emphasis for
pressure distribution on the bound-down
scar area in the lumbar region, as well as
thoracic support for the amputated side (see Figures
4a
, 4b
, 4c
and 4d
). A lumbar pad was made from 1/4inch Aliplast® and 1/4-inch Plastazote® with
the Aliplast positioned in contact with the
modified patient mold.
The lumbar pad was skived from the Plastazote side and lightly tacked to the modified
patient mold with rubber cement to keep the
lumbar pad in place for drape molding. The
rubber cement easily peeled off the Aliplast
after fabrication. Two strips of firm Plastazote were cut and nailed into the modified
mold along the hemipelvectomy lateral side
to provide corrugations for strength. (Note:
Corrugations may not be necessary due to
the thickness of socket material used and
structural design of the eventual socket retainer base. Corrugations were used in this
case due to the unknown outcome during
this limited length of admission and thc authors' tendency to want to err toward safety).
The prototype diagnostic socket was then
fabricated using traditional drape molding
techniques over the modified patient mold,
lumbar pad and the lateral corrugations of
4-inch Surlyn®. This prototype socket was
then evaluated on the patient, noting areas
of excessive pressure and lack of contact.
Further trimline modifications were marked;
lateral and posterior plumb lines were established to maintain the proper alignment of
the socket.
After patient evaluation, the prototype
socket was modified and a Durathane® foam
base was poured with the lateral and posterior plumb lines held in proper orientation.
The foam base was then shaped to provide
an appropriate base of support and proper
cosmesis so the patient could fit his pants
over the device without modification.
Pressure-Mapping Technique
Before initiating a program of wearing tolerance with the device, the patient was seen in
the CRT Pressure Study Clinic to determine
an appropriate seat cushion. A pressure-mapping device determined the relative interface pressures between the patient's base
of support (the device and left ischium) and a
cushion (see Figure 5
). The Spiral Pressure-Mapping System is a l44-electrode grid map
connected to an IBM-PC compatible computer (6). During evaluation, the patient sits
on the map, which lies on top of a cushion.
The map is inflated so none of the internal
electrodes are in contact. Air is released
from the map, and as each electrode makes
contact, the computer records the map's internal pressure. At the completion of a test,
the computer screen displays a grid of pressure readings (see Figure 6a
, and Figure 6b
). This grid
provides information on quantitative peak
pressures and weight distribution to reflect
positional symmetry of the pelvis at a given
moment.
This patient was evaluated with the prototype device while sitting on a three-inch
polyurethane foam cushion of 3 LB/ft density
and medium stiffness, mounted on a firm
board. The map indicated even distribution
from left to right and no peak pressure greater than 30 mm Hg (which was our criterion
for maximal acceptable reading) under the
left ischial tuberosity.
The patient received instructions in the
push-up method of pressure relief to be performed every half-hour. He was able to independently clear his buttock and device from
the cushion surface and hold the position for
45-60 seconds.
Implementation
The patient then began daily physical therapy lessons. We closely monitored signs of
unusually high pressures and problem areas,
especially on the insensate residual limb and
contralateral intact ischial tuberosity. Due to
the patient's high susceptibility to pressure
sores, a regimen of increasing wearing tolerance was initiated beginning at, and increasing by, 15-minute intervals with regular skin
checks.
The patient wore the prototype device for
approximately two months while increasing
the wearing tolerance from 15 minutes to six
hours. During this time, the device was modified to allow for more comfort and fewer
restrictions, to maintain proper postural support, to prevent skin breakdown and to allow
independence in wheelchair mobility and
transfers.
Definitive Seating Device
With the acceptable pressure-mapping results, six-hour skin tolerance of the prototype device, and both patient and staff satisfaction with modifications to the device (for
comfort and function), it was now time to
fabricate the definitive seating system.
The prototype device was filled with plaster, incorporating all of the modifications
and established trimlines. Plaster filled in the
lateral corrugation spaces, thus providing an
exact plaster duplication of the corrugation
struts.
The definitive lumbar Aliplast-Plastazote
pad was extended to provide comfort for the
remaining iliac crest-a need identified
through the evaluation period with the prototype device.
The socket was again drape-molded, using
1/4-inch Surlyn, and the seam was strategically placed on the anterior section, which
would be cut out to allow donning. Trimlines
were transferred to the socket from the modified mold and were trimmed and finished.
The socket was then placed back on the
mold, and a plaster base was poured and
sculptured, according to the established
plumb lines, to represent the appropriate
base of support that would be provided by
the polypropylene socket retainer (similar to
thermoplastic above-knee socket/retainer
procedures).
A piece of 1/2-inch polypropylene was then
drape-molded over the plaster buildup and
inner socket. Once the outer shell was
trimmed and the plaster removed, the polypropylene outer base and inner socket were
attached as a modular system by riveting the
two sections at various points for stability.
Counter-sinking the rivet heads was necessary. This procedure provided a custom seating system that was lightweight yet strong
enough to support the patient in all activities
(see Figure 7
, Figure 8a
, Figure 8b
, Figure 9a
, Figure 9b
, Figure 9c
, and Figure 10
).
Upon completing the definitive seating
system, a pressure-mapping evaluation with
the new device was performed. The pressure-mapping readings for the definitive system were within normal acceptable limits (30
mm HG).
Conclusion
The device described met the criteria: It was
lightweight, mobile and provided symmetrical weight distribution in sitting. The patient
was able to tolerate six hours of sitting without upper extremity support and achieved
independence in pressure relief, wheelchair
mobility skills and transfers.
While using the definitive device, the patient wore a custom bodysock as an interface
and suspenders to prevent the sock from rolling down inside the socket.
Such a device provides the wheelchair bound hemipelvectomy patient with a stable
base of support for independent sitting and
return of functional status. [Note: The TIPE
Pad and SPIRAL MONITOR are no longer
commercially available. Comparable systems are currently being developed by several companies (7).]
Acknowledgments
The authors would like to express their sincere
gratitude to Donald Toscano, prosthetic/orthotic
technician, for his invaluable assistance in the design and fabrication of this device. The lead author would also like to acknowledge David K.
Bow, CPO, for ideas from previous patients that
assisted in the development of this project as well
as James Hoehne, CO, for his assistance in the
fabrication of this device. The figures appearing
in this article are the work of photographer Brian
Yarborough of the Audio Visual Department.
David F. Moretto, BS, CP, is director of orthotics
and prosthetics at Helen Hayes Hospital's Center
for Rehabilitation Technology, Rt. 9W, West Haverstraw, NY 10993; (914) 947-3000, ext. 3122.
Jean L. Minkel, MS, PT, is a seating and mobility rehabilitation technology specialist at Helen
Hayes Hospital's Center for Rehabilitation Technology, Rt. 9W, West Haverstraw, NY 10993.
Mary D. Cardi, MS, PT, is assistant director of
Helen Hayes Hospital's Center for Rehabilitation
Technology, Rt. 9W, West Haverstraw, NY
10993.
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