A Reciprocation Prosthesis for a Patient with Sacral Agenesis

LOU EKUS, CPO, LEON KRUGER, MD,AND NEIL FERGUSON, CPT*Shriners Hospital for Crippled ChildrenSpringfield, Massachusetts


Many congenital deficiencies present difficult and varied problems to rehabilitation specialists. Few deficiencies, however, tax creativity and skill more than lumbosacral agenesis, a congenital absence of the lumbar spine and sacrum. The condition has been well described1,2,3. The so-called Buddha limbs with flexion/abduction/external-rotation deformity at the hips, flexion deformities at the knees and equinus deformities at the feet are of no use to the patient and prevent any reasonable approach to management with orthoses or prostheses. Prosthetic limbs with a central opening to permit the limbs to protrude have proved unsatisfactory.

In 1966 Aitken and Frantz described their approach to treatment with a program for a child with lumbosacral agenesis. They recommended bilateral subtrochanteric amputation, followed by prosthetic restoration. The prosthesis had a bucket socket with bilateral Canadian-type hip-disarticulation limbs beneath the socket. The patient could lift himself into and out of the prosthesis. With the aid of crutches or a walker he could ambulate quite effectively at home with a swing-to gait.

In the hospital we have used the Louisiana State University (LSU) reciprocation-gait orthosis for children with high-level myelomeningocele and are impressed with the four-point gait facilitated by the device4. We reasoned that the orthosis might be effective for a young girl with bilateral hip disarticulations.

The new prosthesis allows the child to walk with a reciprocal gait, greatly increasing stability and apparently decreasing energy expenditure for ambulation. The two benefits yield a large functional difference between her old prosthesis and the new.

Case Report

Y.R. was first seen on May 6, 1978, at 4 years of age and presented lumbosacral agenesis with absence of the lumbar spine and sacrum and lower limbs in the classic Buddha position. After discussion of treatment possibilities with her parents, the procedure of choice was bilateral subtrochanteric amputation and prosthetic restoration as described by Aitken and Frantz3.

She was admitted to our hospital five months later. Bilateral subtrochanteric amputations were performed, following which she was fitted with bilateral Canadian hip prostheses.attached to a bucket socket with shoulder-strap auxiliary suspension. She used the prosthesis until she was readmitted five years later for replacement of the prosthesis. At this time the decision was made to design a reciprocal-gait bilateral hip-disarticulation prosthesis.

Molding Procedure

Because of the absence of part of the spine, when the patient sits, the pelvis is flexed under the lower spine, but when she supports herself on her hands, the pelvis hangs in an extended attitude under the spine. Consequently, she was casted in a hanging sling which supported her in very much the same way a socket would support her (Figs. 1 and 2 ). The 12th thoracic vertebra at the end of the spine was allowed to protrude posteriorly upon weight-bearing through the torso. The lower area and the costal margins were built up slightly on the model; however, the rest of the model remained unmodified.

Materials and Fabrication

Reciprocal action is achieved by utilizing the LSU reciprocating-joint system 4-. Because the orthotic joints are not fully weight-bearing as required in a prosthesis, it was necessary to add another weight-bearing member on the medial aspect of each leg. This was accomplished by modifying a standard Canadian hip joint to allow for reciprocal motion of one arm in relation to the other. A modified Canadian joint was attached medially to the LSU joint on each leg. The centers of the two lateral LSU reciprocating joints and the medial Canadian joints were aligned so they were completely congruous, by placing a rod through the centers of all joints and squaring them to one another.

The prosthetic legs were provided with manually locked knee units. Static alignment was similar to that used for a standard hip-disarticulation prosthesis. Proximally, the hip joints were placed so that a vertical line from the joints fell approximately 4 cm (1 1/2 in.) in front of the ankle bolt of the foot.

Socket alignment was determined by seating the patient in the socket and finding a comfortable balancing point. Vertical and horizontal lines were then drawn on the socket as reference lines for socket attachment. The socket was attached to the hip joints so that the sagittal socket midline was aligned with the center of the hip joints laterally. The alignment produced an extremely stable prosthesis.

To maintain both legs in correct alignment during the complex alignment procedure, a piece of plywood was placed to act as a rigid attachment of both ankle blocks (Fig. 3 ). The wooden bar maintained the legs in constant alignment relative to each other during fabrication. Knee-joint axes were placed parallel to the hip joint axes. Reciprocator-cable attachment points were in the same place as has been described for orthotic use4, but onto wooden blocks. The blocks were fastened to the socket with polyester resin. The patient walked in the unfinished apparatus to see if she could operate it. After all alignment adjustments were satisfactory, the finishing process was started.


The legs were shaped in the standard manner. The posterior aspect of the socket was shaped like buttocks to improve the draping of slacks. Standard polyester resin lamination was performed, and all attachment points were trimmed after the lamination procedure (Fig. 4 ).


The first time the patient tried the prosthesis in the parallel bars she was able to walk with a reciprocal gait. Her standing balance was much better than with her previous prosthesis. She felt more stable while standing and walking and stated that ambulation was much easier now. With the finished prosthesis she could walk very effectively with a walker. Within two days she had progressed to forearm crutches, remaining stable while decreasing her step length slightly (Fig. 5 ).


Standing ability was increased in the reciprocation prosthesis because the hip and knee joints remained locked in full extension, placing the socket on a rigid pedestal, unlike the standard unlocked prosthetic joints which may cause a patient to "jack-knife". The reciprocal-gait pattern appears to require much less energy than the "swing-to" or "swing-through" gait and is more stable, because one foot is always on the floor. The patient was chosen for the experimental prosthesis because she was already able to ambulate in a standard prosthesis with a "swing to" gait. Her initial positive response to the prosthesis is based upon improved functional and cosmetic restoration.


A 9-year-old girl with bilateral subtrochanteric amputations secondary to complete lumbosacral agenesis was fitted with a newly designed bilateral hip disarticulation prosthesis which incorporated the LSU reciprocating-joint system. The patient now walks with a reciprocal gait.

*Shriners Hospital for Crippled Children, 516 Carew Street, Springfield, MA 01104


  1. Russell, H. E., and G. T. Aitken: Congenital Absence of the Sacrum and Lumbar Vertebrae with Prosthetic Management. J Bone Joint Surg 45-A: 501-508, 1963.
  2. Sinclair, J. G., Norman Duren and J. C. Rude: Congenital Lumbosacral Defect. Arch Surg 43: 474-478,1941.
  3. Frantz, C. H., and G. T. Aitken: Complete Absence of the Lumbar Spine and Sacrum. J Bone Joint Surg 49-A: 1531-1540, 1967.
  4. Douglas, Roy, Paul G. Larson, Robert D'Ambrosia and Richard McCall: The LSU ReciprocationGait Orthosis. Orthop 6: 834-839, 1983.