American Academy of Orthotists & Prosthetists
Professionals Advancing Care Through Knowledge
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 AliplastR and 1/4-inch PlastazoteR 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 SurlynR. 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 DurathaneR 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.
References:
- Vaughan V, McKay R, Nelson W., ed. Nelson Textbook of Pediatrics, 10th ed. W.B. Saunders, Philadelphia, Pa., 1975:1412.
- Anderson E, Spain B. The Child with Spina Bifida. Methuen & Co. Ltd., London, England, 1977: 13-14.
- Menelaus M. The Orthopaedic Management of Spina Bifida Cystica, 2d ed. Churchill Livingstone, New York, N.Y., 1980:2-3.
- American Academy of Orthopaedic Surgeons, Atlas of Limb Prosthetics, Surgical and Prosthetic Principles. C.V. Mosby, St. Louis, Mo., 1981:408-409.
- Carlson MJ, Lonstein J, Beck K, Wilkie D. Seating for children and young adults with cerebral palsy. Clinical Prosthetics and Orthotics Nov. 4, 1986;10:137-158.
- Jaros L. The Spiral Pressure Monitor, Instruction manual, Rehabilitation Engineering Program, Department of Physical Medicine and Rehabilitation, University of Michigan Medical Center, Ann Arbor, Mich., copyright 1987, The Regents of the University of Michigan.
- Talley Group, Medical Equipment Division, Premier Way, Abbey Park Industrial Estate, Romsey, Hants S051 9AK, England; telephone: 0794 830866; fax: 0794 830702.
- Vision Engineering Research Group (VERG), 211 Oak St., Winnipeg, Manitoba Canada R3M 3P7; (204) 942-2337.
- TEKSCAN Inc., 451 D St., 4th Floor, Boston, MA 02210-1901; (800) 248-3669, (617) 737-8734.
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