BODY PROSTHESIS. BY DANIEL SHAW, MAXILLOFACIAL PROSTHETIST Leave a comment

As part of the editorial team, I hope to bring in interesting and innovative aspects of Maxillofacial Technology/Healthcare Science into our magazine.

INTRODUCTION

In this particular case study, I’m giving you a body prosthesis case of a very sensitive nature. A new mother went to her antenatal, mid-term ultrasound (20-week) scan where Spina Bifida was diagnosed within the foetus. This however, wasn’t the main concern at this stage; it was the presence of a sacrococcygeal teratoma tumour, at the base of the coccyx. Mother had 2-week appointments to drain fluid from her womb to avoid premature labour. Yet, at week 35, labour was brought on through a cut at one of the fluid draining appointments.
The baby girl was Born at 11lb via Standard C Section which was necessary due to the size of the tumour. On Day 4 it was tumour removal day and shockingly, it was estimated that half of the birth weight was that of the tumour itself. The young girl continues to have regular check-ups to ensure there are no further complications as her body grows.
In 2019, at the age of 11, the patient was referred to myself for some form of prosthetic camouflage.
Fig i and ii shows the extent of the scarring and also the lack of projection of the left buttock.

CONSIDERATIONS

The requirements needed to provide this patient with an adequate prosthesis were relatively simple;

  • What does the patient want and what does she want the prosthesis to do for her?
  • What are the options available to her?
  • How will hygiene be best managed?
    In terms of the prosthesis;
  • What will the weight of the prosthesis be and can this be reduced?
  • What will its size and extension be?
  • How will it be attached to the body in the correct location and orientation?
WORKFLOW AND PROCESS

In order to start any form of prosthetic work, it must follow from an accurate impression of the defect site. I used an old tested impression technique that was taught me by the late Liz Gill where alginate impression material [Schottlander Fidelity 25] was packed onto the surface. Large paper clips were bent and embedded into the alginate prior to setting, to form a key system which allows the plaster backing to accurately support the less stable alginate. Although the prosthesis was intended to sit unilaterally, it was necessary to encapsulate the form of the right buttock to try and match the space lost. (fig iii)
The whole mould was then cast in a type iv stone (Crystacal R [John Winters]), but there needed to be an inhibitor to prevent the backing plaster integrating into the Crystacal working model. For this I sprayed the periphery of the impression backing with MacWax [PolyMed ltd] release agent. (fig iv)
With the same technique of wax separation as with denture manufacture, the mould was soaked for 15 minutes and then dried. A combination of standard modelling wax and thin casting wax was used to form the try-on prosthesis. Casting wax was used as it is thinner and therefore quicker to adjust in clinic. The try-on was satisfactory (fig v) as it formed adequate coverage and fitted to the surface well. I then performed a second impression, this time with the patient laid on her front. Once this second mould was cast, the wax-up matrix was tried on to it to assess how much the buttock would move.
M511 silicone [Technovent UK] was then colour matched to a natural shade with no great accuracy, as it wouldn’t be a prosthesis that would be visible to anyone. Only the shape and form were required.
One of the crucial aspects of the comfort and usability of this prosthesis was its weight. A prosthesis made purely of silicone would have been extremely heavy and no doubt uncomfortable. Therefore, it was decided to form a silicone sponge matrix that would act as the body with and skin coloured silicone style “glove”.
To achieve this, to two parts of silicone sponge [A-3200-G Technovent] were mixed and packed into the invested wax mould (fig vi). Once cured, it was removed and cut to a smaller shape to allow room for the skin colour silicone within the same mould. Iso-Sep [John Winters] coated the entire surface and was allowed to dry fully, before packing. The skin colour silicone was then added around the sponge to encase it (fig vii). Once packed, the flask was firmly closed, and the silicone allowed to cure with RTV (room temperature vulcanisation) over the weekend. Post cure, any excess was trimmed with scissors and the whole surface was checked and trimmed as necessary to prevent any discomfort.
At the fit appointment it was apparent that the overall projection was inadequate, however it would act as a good starting point to establish whether the patient would be happy wearing a prosthesis in such a sensitive area (fig viii and ix).
I gave the patient a month appointment for her to see how comfortable it was. It wasn’t particularly comfortable as she found the material too hard. She felt that she didn’t want any further prosthesis making for her at this point, therefore I suggested purchasing some padded shapewear underwear and to cut out the filler on the right side of the undergarment so that under clothing, little discrepancy would be noticeable. The patient and her mum were both happy with this suggestion.
The conclusion that stands out in this particular case study is that of providing the patient with exactly what they want.
Important note: for every appointment, the patient’s mother and a nurse chaperone was present alongside me.

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