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Visualization of skin deformation during wound closure
VISUALIZATION OF SKIN DEFORMATION WOUND CLOSURE and P. Bowkert
J.M. Gill*
ABSTRACT A simple technique is described which enables the accurate visuulization of
Keywords:
DURING
Skin, wound closure, skin deformation,
skin deformation following wound closure. Results obtained during two surgical procedures involving the excision of areas of skin are presented
surgery
INTRODUCTION Following the excision of an area of skin, the remaining skin around the defect must be deformed if primary closure is to be achieved. The extent of the deformation depends not only on the size of the defect, but also on the degree of undermining and on the mechanical properties of the wound margins; it cannot be predicted. An immediate indication of this deformation would however be of considerable interest to the surgeon.
surgical team. Therefore, a record of the configuration of the grid was obtained by tracing it carefully on to a sterile sheet of transparent flexible polythene (Surgikos Ltd) with permanent marker pens. The method
finally adopted was as follows:
1.
The rubber stamp, ink pad and marker pens were sterilized by placing them in paraformaldehyde vapour for 24 h.
METHOD
2.
The operation
To enable deformation to be measured, there must be reference points on the skin which can easily be identified throughout the operation. These were initially provided by a grid of squares each 10 x 10 mm, within a frame, 70 x 70 mm, printed on the skin by a rocker mounted rubber stamp. In any comparison between operation stages (for example before excision, after excision, after closure) it might be supposed that the large square could act as the fixed reference frame and photographs taken of the grid could record the skin deformation. In practice, however, two modifications to this method were found to be necessary.
3.
The grid was printed on the skin with Bonney’s Blue and allowed to dry. At least two reference points were also marked on the skin well away from the operation site.
4.
A tracing was taken of the grid before any incisions were made. This was necessary because the soft tissues could have yielded beneath the rubber stamp as it was being applied, giving a distorted grid.
5.
The operation
6.
A tracing was again made.
Firstly, it was apparent that the outer margin of the grid was not always immune from deformation and therefore it could not be used to define the fixed frame. Other reference points had to be marked on the skin, as far away from the operation site as was practically possible. Secondly, if the photographs were to be used to measure distances it was vital that the camera was perpendicular to the plane of the skin and that there was no curvature of the skin surface. These conditions can rarely be guaranteed, especially since leaving the camera in one fured position throughout the operation would interfere with the
Department of B&Medical Aberdeen, Aberdeen, UK *Present address: Department Newcastle upon Tyne, UK +Present address: Department Salford M5 4WT, UK
Physics and Bio-Engineering,
University of
of Mechanical
Engineering,
University of
of Orthopaedic
Mechanics,
University of
was performed.
This procedure added less than five minutes total operating time.
to the
RESULTS The procedure
has been used for 13 patients.
Tracings made during one of the operations (the excision of a lump 12 mm in diameter from the left calf) are presented in Figure I(+). The initial and final tracings are shown superimposed in Figure 2 to illustrate the skin deformation. Even without use of the reference grid the ability to take tracings from the skin during surgery proved to be useful in visualizing and recording skin deformation. Following excision of a lesion on the lower right lip the proposed outline of a Limberg flap was traced, Fiaure 3(u). The final configuration of the flan. shown in Figure 3(b), could clearly not have been predicted from simple geometry’. 1
0 1985 Butterworth & Co (Publishers) 0141-5425/85/020161-03 $03.00
site was prepared.
I
Ltd J. Biomed Eng. 1985, Vol. 7, April
161
J.M. Gill and I? Bowker
Skin deformatim
-
Initial tracing
- - - - Final tracing
Incision
lines
a
Figure 2 Superimposition of initial and final tracings from Figure I to demonstrate overall deformation
there are references describing the tracing of flap.@. The technique could further be used to obtain the strain in each small squar$. ACKNOWLEDGEMENTS
b
This work formed part of a study undertaken at Woodend General Hospital, Aberdeen, in collaboration with Mr I. F. K. Muir, Consultant in Plastic and Reconstructive Surgery. J.M. Gill was funded by a Research Studentship from the Medical Research Council during the study.
A
C Figure 1 Tracings made during the operation for the excision of a lump from the left calf: a, initial tracing showing planned incision lines; b, after excision of lesion; c, after wound closure
a
A
DISCUSSION Furnas and Fische3, in their classic study of the biomechanics of the Z-plasty in dog skin, marked the skin with a pattern of dots, 10 mm apart, and used the distortion of the pattern to determine stretch in the surrounding skin after flap transposition. Webster, Davidson and Smith3, described the use of grids drawn on fresh cadaver skin to demonstrate distortion produced by excisions and closures by most varieties of skin flaps. However, the tracing of a grid to eliminate errors resulting from skin curvature has not been previously described in the literature, although
162
J. Biomed Eng. 1985, Vol. 7, April
9
b
7
Figure 3 Tracings of a Limberg gap for the closure of the skin defect resulting from excision of a lesion on the lower lip: a, planned flap; b, after closure; A, reference point
Skin defonnatiow J.M. Gill and P. BOW~ET
REFERENCES 1
4
Koss, N. The mathematics of flaps. In: Symposium on basic (Eds T.J. Krizek and J.E. Hoopes) New Haven, 1975, 274-283 Furnas, O.W. and Fischer, G.W. The Z-plasty: biomechanics and mathematics. BrJ Plast Swg 1971, 24, 144-160 Webster, R.C., Davidson, T.M. and Smith, RC. The thirty science in plastic sqey
2
3
5
6
degree transposition flap. Lqngoscqbe, 1978, 88, 85-94 I_arrabee, W.F. Jr., Trachy, RE., Sutton, 0. and Cox, K Rhomboid flap dynamics. Arch Otolaryngol 1981, 107, 755-757 Wexler, M.R and Failer, R Flap and wound size tracing on polyethylene sheet. Plast ReconsEr.Surg. 981, 68, 103-104 Wan Abas, W.A.B. and Barbenel, J.C. Uniaxial tension test of human skin in vivo. J Biomed Eng. 1982, 4, 65-7 1
XIV INTERNATIONAL CONFERENCE ON MEDICAL AND BIOLOGICAL ENGWEEBING WHNTEBNATIONALCONFEREN CE ON MEDICAL PHYSKS Espoo l Finland l Augastll-16,1985 The following main themes have been planned: Bioengineering in outer and inner space; Bioengineering in perinatal medicine; Biomagnetism; Biomechanics; Clinical dosimetry; Computer aided radiotheraphy; Medical imaging; Physiological measurements and controls; Quality assurance procedures in radiotherapy; Radiatior safety legislation; Technical aids for the handicapped. Workshops are being planned on the following topics: Assessment of medical technologies (organized by the WHO, European Regional Office); Clinical engineeriq (organized by the IFMBE clinical engineering working group); Biomedical innovation: mechanisms and implications; Aids for the developing countries (joint session of the IOMP and EFOMP); Debate club: Is Bioengineering harmful to society? Further information: XIV ICMBE/VII
Secr&ariat,
P.O. Box 105. SF-251
J. Biomed Eng. 1985, Vol. 7, April
163
J.M. Gill*
ABSTRACT A simple technique is described which enables the accurate visuulization of
Keywords:
DURING
Skin, wound closure, skin deformation,
skin deformation following wound closure. Results obtained during two surgical procedures involving the excision of areas of skin are presented
surgery
INTRODUCTION Following the excision of an area of skin, the remaining skin around the defect must be deformed if primary closure is to be achieved. The extent of the deformation depends not only on the size of the defect, but also on the degree of undermining and on the mechanical properties of the wound margins; it cannot be predicted. An immediate indication of this deformation would however be of considerable interest to the surgeon.
surgical team. Therefore, a record of the configuration of the grid was obtained by tracing it carefully on to a sterile sheet of transparent flexible polythene (Surgikos Ltd) with permanent marker pens. The method
finally adopted was as follows:
1.
The rubber stamp, ink pad and marker pens were sterilized by placing them in paraformaldehyde vapour for 24 h.
METHOD
2.
The operation
To enable deformation to be measured, there must be reference points on the skin which can easily be identified throughout the operation. These were initially provided by a grid of squares each 10 x 10 mm, within a frame, 70 x 70 mm, printed on the skin by a rocker mounted rubber stamp. In any comparison between operation stages (for example before excision, after excision, after closure) it might be supposed that the large square could act as the fixed reference frame and photographs taken of the grid could record the skin deformation. In practice, however, two modifications to this method were found to be necessary.
3.
The grid was printed on the skin with Bonney’s Blue and allowed to dry. At least two reference points were also marked on the skin well away from the operation site.
4.
A tracing was taken of the grid before any incisions were made. This was necessary because the soft tissues could have yielded beneath the rubber stamp as it was being applied, giving a distorted grid.
5.
The operation
6.
A tracing was again made.
Firstly, it was apparent that the outer margin of the grid was not always immune from deformation and therefore it could not be used to define the fixed frame. Other reference points had to be marked on the skin, as far away from the operation site as was practically possible. Secondly, if the photographs were to be used to measure distances it was vital that the camera was perpendicular to the plane of the skin and that there was no curvature of the skin surface. These conditions can rarely be guaranteed, especially since leaving the camera in one fured position throughout the operation would interfere with the
Department of B&Medical Aberdeen, Aberdeen, UK *Present address: Department Newcastle upon Tyne, UK +Present address: Department Salford M5 4WT, UK
Physics and Bio-Engineering,
University of
of Mechanical
Engineering,
University of
of Orthopaedic
Mechanics,
University of
was performed.
This procedure added less than five minutes total operating time.
to the
RESULTS The procedure
has been used for 13 patients.
Tracings made during one of the operations (the excision of a lump 12 mm in diameter from the left calf) are presented in Figure I(+). The initial and final tracings are shown superimposed in Figure 2 to illustrate the skin deformation. Even without use of the reference grid the ability to take tracings from the skin during surgery proved to be useful in visualizing and recording skin deformation. Following excision of a lesion on the lower right lip the proposed outline of a Limberg flap was traced, Fiaure 3(u). The final configuration of the flan. shown in Figure 3(b), could clearly not have been predicted from simple geometry’. 1
0 1985 Butterworth & Co (Publishers) 0141-5425/85/020161-03 $03.00
site was prepared.
I
Ltd J. Biomed Eng. 1985, Vol. 7, April
161
J.M. Gill and I? Bowker
Skin deformatim
-
Initial tracing
- - - - Final tracing
Incision
lines
a
Figure 2 Superimposition of initial and final tracings from Figure I to demonstrate overall deformation
there are references describing the tracing of flap.@. The technique could further be used to obtain the strain in each small squar$. ACKNOWLEDGEMENTS
b
This work formed part of a study undertaken at Woodend General Hospital, Aberdeen, in collaboration with Mr I. F. K. Muir, Consultant in Plastic and Reconstructive Surgery. J.M. Gill was funded by a Research Studentship from the Medical Research Council during the study.
A
C Figure 1 Tracings made during the operation for the excision of a lump from the left calf: a, initial tracing showing planned incision lines; b, after excision of lesion; c, after wound closure
a
A
DISCUSSION Furnas and Fische3, in their classic study of the biomechanics of the Z-plasty in dog skin, marked the skin with a pattern of dots, 10 mm apart, and used the distortion of the pattern to determine stretch in the surrounding skin after flap transposition. Webster, Davidson and Smith3, described the use of grids drawn on fresh cadaver skin to demonstrate distortion produced by excisions and closures by most varieties of skin flaps. However, the tracing of a grid to eliminate errors resulting from skin curvature has not been previously described in the literature, although
162
J. Biomed Eng. 1985, Vol. 7, April
9
b
7
Figure 3 Tracings of a Limberg gap for the closure of the skin defect resulting from excision of a lesion on the lower lip: a, planned flap; b, after closure; A, reference point
Skin defonnatiow J.M. Gill and P. BOW~ET
REFERENCES 1
4
Koss, N. The mathematics of flaps. In: Symposium on basic (Eds T.J. Krizek and J.E. Hoopes) New Haven, 1975, 274-283 Furnas, O.W. and Fischer, G.W. The Z-plasty: biomechanics and mathematics. BrJ Plast Swg 1971, 24, 144-160 Webster, R.C., Davidson, T.M. and Smith, RC. The thirty science in plastic sqey
2
3
5
6
degree transposition flap. Lqngoscqbe, 1978, 88, 85-94 I_arrabee, W.F. Jr., Trachy, RE., Sutton, 0. and Cox, K Rhomboid flap dynamics. Arch Otolaryngol 1981, 107, 755-757 Wexler, M.R and Failer, R Flap and wound size tracing on polyethylene sheet. Plast ReconsEr.Surg. 981, 68, 103-104 Wan Abas, W.A.B. and Barbenel, J.C. Uniaxial tension test of human skin in vivo. J Biomed Eng. 1982, 4, 65-7 1
XIV INTERNATIONAL CONFERENCE ON MEDICAL AND BIOLOGICAL ENGWEEBING WHNTEBNATIONALCONFEREN CE ON MEDICAL PHYSKS Espoo l Finland l Augastll-16,1985 The following main themes have been planned: Bioengineering in outer and inner space; Bioengineering in perinatal medicine; Biomagnetism; Biomechanics; Clinical dosimetry; Computer aided radiotheraphy; Medical imaging; Physiological measurements and controls; Quality assurance procedures in radiotherapy; Radiatior safety legislation; Technical aids for the handicapped. Workshops are being planned on the following topics: Assessment of medical technologies (organized by the WHO, European Regional Office); Clinical engineeriq (organized by the IFMBE clinical engineering working group); Biomedical innovation: mechanisms and implications; Aids for the developing countries (joint session of the IOMP and EFOMP); Debate club: Is Bioengineering harmful to society? Further information: XIV ICMBE/VII
Secr&ariat,
P.O. Box 105. SF-251
J. Biomed Eng. 1985, Vol. 7, April
163