Prosthetic Management of a Partial-Foot Amputee

DONALD J HAYHURST, C.P.O.


Prior to November 1973, our facility used silastic shoe fillers as the treatment for children with partial-foot amputations. This procedure worked fairly well, but all of the patient's shoes would have to be filled. The shoes had a tendency to break down at the point where the residual limb and the silastic joined. Because the amputee could not get an adequate pushoff, a somewhat unsightly gait resulted.

In November 1973, a young lady came into our clinic wearing a prosthesis that was made in a Canadian facility. Since the name of the facility is unknown to us, we are unable to give a specific acknowledgment. Since that time we have been using the same type of prosthesis with little modification. Our patients prefer the prosthesis over the silastic filler. The shoes appear to hold up better, the patient's gait is improved, and the child can wear virtually any type of shoe.

Our clinic has made 12 prostheses for six patients, of which all are average or above average in activity. The patients consist of four girls and two boys. Three girls, one of whom is bilateral, and one boy are congenital amputees. The remaining boy and girl are lawnmower-induced traumatic amputees. The mothers of three of the congenital amputees stated that they had taken some kind of medication during the early stages of gestation.

Fabrication

1. Check to see whether the pelvis is level ( Figure 1 ). In a congenital absence, the affected side is usually shorter than the sound side, thus allowing space for thickness of the partial-foot prosthesis.

2. All bony prominences ( Figure 2 ) are marked. These prominences are the medial and lateral malleoli, the calcaneus, and any other potential problem areas. The approximate line of progression is marked on the anterior residual limb.

3. A negative mold is taken with alginate.

4. The negative mold is immediately filled with plaster. A mandrel is placed in the plaster.

5. After the alginate is removed from the plaster, all marked areas are remarked with indelible pencil to insure that no plaster is removed from these areas.

6. Plaster is now removed from the medial and lateral aspects of the calcaneus tendon, as indicated by the shaded areas in Figure 3 . Sufficient plaster is removed (approximately 0.8 mm) if the indelible markings of the shaded areas are shaved away with a Scarpa's knife. No more plaster is to be removed.

7. With nails as guides, prominences are built up approximately 1.5 mm (1/16 in.) with plaster. The mold is smoothed, dried, and sealed. We use an industrial lacquer to seal our molds.

8. A two-ply or a three-ply stump sock is placed on the mold, and a sheet of PVA is stretched over the mold ( Figure 4 ). Vacuum is used to draw the PVA to the mold.

9. The lamination layup requires one layer of one-ounce dacron and six layers of nylon stockinette sewn on one end. Sewn ends arc placed on the distal anterior socket. A PVA bag is now used. Polyester resin is used in proportions of 70 per cent rigid resin (Laminac 4110) and 30 per cent flexible resin Laminac 4134).

10. After the resin cures, approximate trim lines are marked ( Figure 5 and Figure 6 ). The lateral and medial cuts that allow easy donning and removing of the prosthesis are determined by bisecting both malleoli. Before cutting is done on these lines, a 15/64-inch hole is drilled as close as possible to the plantar surface at the base of the perpendicular line ( Figure 6 ). This hole helps to prevent cracking or tearing of the material.

11. A SACH foot that has been fitted slightly looser than usual is now cut to receive the length of the socket ( Figure 7 ).

12. Surgical tubing, with Vaseline or silicone applied to it, is placed between the socket and the cut SACH foot ( Figure 8 and Figure 9 ). After the socket and SACH foot are bonded together with resin, wood chips, and solka floc, the tubing is removed to allow more flexibility for donning and removing the prosthesis.

13. The prosthesis is ready for ambulation of the patient, and all problems are to be corrected at this time. If adequate suspension is not achieved, an elastic strap can be attached to the anterior portion of the socket and run around the posterior section ( Figure 10 ).

14. The finished prosthesis is covered with deerskin. Figure 11 , Figure 12 , and Figure 13 show the finished prosthesis.

Conclusion

The molded partial-foot prosthesis has several advantages:

  • Total-contact socket fit reduces skin problems
  • Shoes last longer
  • Gait is more acceptable
  • The patient can wear any type of shoe.

Patients particularly appreciate the advantage of knowing that they do not have to come in to see us every time they buy a new pair of shoes.