- Email: [email protected]
New economical skin graft expansion wheel
Bums (1992) 18, (2), 157-158
Printed in Great Brikaain
157
New economical skin graft expansion wheel A. Vartak Bums Research
Unit, B. J. Wadia Hospital
for Children, Parel, Bombay, India
A simple and economical mesh graft expansion wheel is described The instrument does not need any consumables - carrkrs for example - ana’is very low priced compared with other expanders. A small institution or a private practising surgeon in this county can afford if. It is possible to increase or redtcce the number of wheels to individual surgeon’s requirements. Different expansion ratios can be obtained by simple changes in design.
The cost of this instrument and its cutting board is only a small fraction of that of the commercially available skin graft meshers.
Introduction A mesh graft is a split skin graft which has multiple, staggered uniform slits cut in it. The graft can then be expanded at right angles to the line of the slits. The amount of expansion depends upon the length of, and the distance between each slit. The value of this expansion is appreciated by surgeons who need to cover large skin defects. For patients with bums and other extensive injuries, mesh grafts can be a great boon. Tanner et al. (1964) described a useful device which could rapidly and uniformly cut skin grafts and permit their expansion. The technique of mesh grafting is now practised worldwide. However in India this method is rarely used because of the high cost of both the instrument and the carriers. A simple mesh grafter has been designed which is very much cheaper and yet is still very effective.
Figure 1. A, Snacks cutting wheel. B, Skin graft expansion wheel - first model.
Concept and instrument design The simple wheel cutter which is commonly used in Indian kitchens for cutting certain types of food snacks was the germinal idea (Figtrre IA). From this idea a wheel with four circular blades with cutting edges interrupted at intervals was designed (Fimre IB). A single run of the wheel can make four rows of staggered, interrupted parallel cuts through the surface of a soft material such as cloth or skin. In our experience four blades were found to be adequate, although it is possible to increase the number of blades. With more than four blades however the pressure required to obtain clean cuts is greater. The potential need for greater pressure dictated a revised design (Figure 2) to prevent the possibility of the surgeon’s thumb slipping forward with the risk of injury. The added thumb guard also made it possible to apply additional pressure with the other hand to facilitate even cutting. (0 1992 Butterworth-Heinemann 0305-4179/92/020157-02
Ltd
Figure 2. Skin graft expansion wheel - second model with close-up view shown.
158
Bums (1992) Vol. IS/No.
Figure 3. Expansion wheel in use (first model).
Figure 4. Skin graft after making cuts.
Technique
Sg = surface gained E = elasticity of the skin (0.626* for one unit surface area) N = number of cuts 1 = length of cuts
The instrument is run with adequate pressure lengthwise over the isolated skin surface in parallel lines until the entire width of the skin graft is covered (Figures 3, 4). No skin carrier is required other than the wooden board which is used for stretching the skin during and after its excision. Cutting of the skin on this wooden board limits the blunting effect on the sharp edges of the stainless-steel cutting wheels. Sterilization of the instrument and board is readily accomplished with high pressure steam. The technical details of the instrument and the means by which the cuts can be varied in length and the lateral distance between rows of cuts, to give differing expansion ratios of the skin when meshed, are given in the Appendix.
Acknowledgements I am grateful to Dr M. H. Keswani and Dr J. W. L. Davies for their encouragement and valuable suggestions, to Mrs Aakanksha Patil for her technical assistance and to Mr Sunil Sawant for photographic illustrations. The instrument has been made by Mr V. T. Vora of the Precious Surgical Co., Bombay, India.
Thus in a skin graft measuring
Expansion
ratio = Sm/Si = 2.9
The rate of epithelial cell growth leading to eventual skin regeneration is dependent upon graft border length. With meshing this length can be calculated as follows: BLA = BLi + BLg BLA=2(L+ B)+21N BLA = border length achieved
BLi BLg L B
1
= initial border length = border length gained = length of graft = breadth of graft = length of cut = number of cuts
Thus with a skin graft measuring
Tanner J. C., Vandeputt
J. and Olley J. F. (1964) The mesh skin graft. P/a.& Reconsfr. Surg. 34, 287.
Appendix The current design of the skin graft mesher has four wheels with a cutting edge length of 13 mm, interruption gaps in the cutting edges of 2.5 mm and a space between the wheels of 2 mm. ratios attainable with these The possible expansion dimensions (or others preferred by the users) can be calculated from the formulae published by Tanner et al. (1964):
BLA_2(L+B)+21N =2(6+ 15)+2 =42+298 = 970
6 cm x 15 cm,
x 1.6 x 290
Increase in border length = BLAIBLi = 970/42 = 23 times An expansion ratio which gives a border length that is increased 23 times appears to be satisfactory for most applications. Paper accepted 18 October
Sm=Si+SG+F =Si+N(+))2+E
6 cm x 15 cm,
Sm=Si+N($)2+ExSi = 90 cm’ + 290 (1.30/2)’ + 0.626 x 90 = 90 x 122.525 + 56.34 = 268.865
N
Reference
2
1991.
x Si
where: Sm = maximum surface available Si = initial surface
Correspondence should be addressed lo: Dr A. Vartak, Bums Research Unit, B.J. Wadia Hospital for Children, Parel, Bombay 400 01.2, India.
Printed in Great Brikaain
157
New economical skin graft expansion wheel A. Vartak Bums Research
Unit, B. J. Wadia Hospital
for Children, Parel, Bombay, India
A simple and economical mesh graft expansion wheel is described The instrument does not need any consumables - carrkrs for example - ana’is very low priced compared with other expanders. A small institution or a private practising surgeon in this county can afford if. It is possible to increase or redtcce the number of wheels to individual surgeon’s requirements. Different expansion ratios can be obtained by simple changes in design.
The cost of this instrument and its cutting board is only a small fraction of that of the commercially available skin graft meshers.
Introduction A mesh graft is a split skin graft which has multiple, staggered uniform slits cut in it. The graft can then be expanded at right angles to the line of the slits. The amount of expansion depends upon the length of, and the distance between each slit. The value of this expansion is appreciated by surgeons who need to cover large skin defects. For patients with bums and other extensive injuries, mesh grafts can be a great boon. Tanner et al. (1964) described a useful device which could rapidly and uniformly cut skin grafts and permit their expansion. The technique of mesh grafting is now practised worldwide. However in India this method is rarely used because of the high cost of both the instrument and the carriers. A simple mesh grafter has been designed which is very much cheaper and yet is still very effective.
Figure 1. A, Snacks cutting wheel. B, Skin graft expansion wheel - first model.
Concept and instrument design The simple wheel cutter which is commonly used in Indian kitchens for cutting certain types of food snacks was the germinal idea (Figtrre IA). From this idea a wheel with four circular blades with cutting edges interrupted at intervals was designed (Fimre IB). A single run of the wheel can make four rows of staggered, interrupted parallel cuts through the surface of a soft material such as cloth or skin. In our experience four blades were found to be adequate, although it is possible to increase the number of blades. With more than four blades however the pressure required to obtain clean cuts is greater. The potential need for greater pressure dictated a revised design (Figure 2) to prevent the possibility of the surgeon’s thumb slipping forward with the risk of injury. The added thumb guard also made it possible to apply additional pressure with the other hand to facilitate even cutting. (0 1992 Butterworth-Heinemann 0305-4179/92/020157-02
Ltd
Figure 2. Skin graft expansion wheel - second model with close-up view shown.
158
Bums (1992) Vol. IS/No.
Figure 3. Expansion wheel in use (first model).
Figure 4. Skin graft after making cuts.
Technique
Sg = surface gained E = elasticity of the skin (0.626* for one unit surface area) N = number of cuts 1 = length of cuts
The instrument is run with adequate pressure lengthwise over the isolated skin surface in parallel lines until the entire width of the skin graft is covered (Figures 3, 4). No skin carrier is required other than the wooden board which is used for stretching the skin during and after its excision. Cutting of the skin on this wooden board limits the blunting effect on the sharp edges of the stainless-steel cutting wheels. Sterilization of the instrument and board is readily accomplished with high pressure steam. The technical details of the instrument and the means by which the cuts can be varied in length and the lateral distance between rows of cuts, to give differing expansion ratios of the skin when meshed, are given in the Appendix.
Acknowledgements I am grateful to Dr M. H. Keswani and Dr J. W. L. Davies for their encouragement and valuable suggestions, to Mrs Aakanksha Patil for her technical assistance and to Mr Sunil Sawant for photographic illustrations. The instrument has been made by Mr V. T. Vora of the Precious Surgical Co., Bombay, India.
Thus in a skin graft measuring
Expansion
ratio = Sm/Si = 2.9
The rate of epithelial cell growth leading to eventual skin regeneration is dependent upon graft border length. With meshing this length can be calculated as follows: BLA = BLi + BLg BLA=2(L+ B)+21N BLA = border length achieved
BLi BLg L B
1
= initial border length = border length gained = length of graft = breadth of graft = length of cut = number of cuts
Thus with a skin graft measuring
Tanner J. C., Vandeputt
J. and Olley J. F. (1964) The mesh skin graft. P/a.& Reconsfr. Surg. 34, 287.
Appendix The current design of the skin graft mesher has four wheels with a cutting edge length of 13 mm, interruption gaps in the cutting edges of 2.5 mm and a space between the wheels of 2 mm. ratios attainable with these The possible expansion dimensions (or others preferred by the users) can be calculated from the formulae published by Tanner et al. (1964):
BLA_2(L+B)+21N =2(6+ 15)+2 =42+298 = 970
6 cm x 15 cm,
x 1.6 x 290
Increase in border length = BLAIBLi = 970/42 = 23 times An expansion ratio which gives a border length that is increased 23 times appears to be satisfactory for most applications. Paper accepted 18 October
Sm=Si+SG+F =Si+N(+))2+E
6 cm x 15 cm,
Sm=Si+N($)2+ExSi = 90 cm’ + 290 (1.30/2)’ + 0.626 x 90 = 90 x 122.525 + 56.34 = 268.865
N
Reference
2
1991.
x Si
where: Sm = maximum surface available Si = initial surface
Correspondence should be addressed lo: Dr A. Vartak, Bums Research Unit, B.J. Wadia Hospital for Children, Parel, Bombay 400 01.2, India.