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The free graft
The Free Gra[t--John R. Cobben
THE
FREE GRAFT
J O H N R. COBBETT, East Grinstead A colleague of mine once wrote " A Surgical Registrar should be as familiar with taking a skin graft as he is with emergency craniotomy". I managed to persuade him, before publication, that the comparison was, perhaps, unfortunate. Apart from the comparison itself it'is an unfortunate statement as to most people it implies a degree of difficulty. Perhaps this is the major merit of the free skin graft. It is a quick and easy method out of trouble when there is a defect that will not close with primary suture. D I S A D V A N T A G E S O F FLAPS
A lost pedicle flap is disaster. The patient is left with a noticeable scar on some part of his anatomy, he remains unhealed and he is reluctant to undergo another similar procedure. If a skin graft does not take the only real loss is time of healing as the donor site will be self-healing with no eventual scar. Flaps raised from other parts of the body require careful planning. It is only too easy to cut a flap upside down or a little too short or a little too long. Any surgeon or, indeed, any nurse with a modern graft knife can cut a piece of skin big enough for a hand defect. So grafts are easy, but flaps are difficult. ADVANTAGES OF GRAFTS
To take and attach a free graft is a matter of minutes. Even the simplest distant flap will take a good hour by the time it has been planned, cut, sutured in place, immobilised and the secondary defect closed. So, grafts are quick, flaps are slow--and this may be important when the patient has multiple injuries. So if you have a contaminated wound, or little experience, or are short of time or are just plain doubtful abou,t what to do, put on a free split skin graft. A flap can be used as a secondary, cold, planned procedure if one is needed. Another benefit of the primary graft is that the period of immobilisation is comparatively short. If a flap is necessary it can be done as a cold case when the wounds are healed, when most traumatic oedema has settled and when movement has returned to the joints, under the best possible conditions. However, at least in theory a free graft will not take on a bare cortical bone, bare tendon or bare ligament. It will take on the loose aureolar tissue over ligament and tendon and it will take on periosteum. 1" PERFuSION 4,
Fig. 1 A free graft can survive by perfusion. 112
Vol. 2~
No. 2
1970
The Free Graft--John R. Cobbett
VASCULARISATION What is meant by "take" of a graft? In essence that the graft has become revascularised by the bed. Survival, as opposed to take, of a graft can happen in two ways. First it can live purely by perfu,sion between it and the bed (Fig. 1) and secondly, often much later, by being revascularised. Many grafts live by perfusion for a day or two before vascularisation occurs. Vascularisation itself can occur in two ways--first by gradual in-growth of capillary loops from the bed into the graft (Fig. 2) and secondly by direct anastomosis between cut capillaries in the bed and in the graft (Fig. 3). Obviously, over bare bone, tendon or ligament there is precious little to offer the graft, either by perfusion or by way of cut capillaries. Even in these circumstances the graft will act as a good temporary dressing over such structures and if the area is narrow enough, or small enough, may survive by the phenomenon of "bridging" whereby it received its blood supply from the neigh. bouring graft and hence lives over the avascular structure. So it may still be worth using a free graft even when one or more of these avascular structures form part of the bed. There must be one absolute contraindication though--never, ever, use a free skingraft across an open joint. M E T H O D S OF
SLOW ;~EVASCUL AR I SATION'
"'IMMEDIATE"
REVA SCULARtSATIOt,I
Fig. 2 Revascularisation may take place by ingrowth of capillary loops. Fig. 3 . . . or by direct anastomosis of capillaries. TYPES OF FREE G R A F T T h e composite graft. This is familiar to all as that fragment of finger tip that
has been washed in cetrimide and sewn back in place. It has full thickness skin plus some pulp. Hence "composite". Another form of composite graft is the immediate toe-pulp replacement of amputated finger tip. Composite grafts have an academic interest of their own. Immediately after operation the graft is deathly white. At six hours it is engorged and blue-black; engorged with what? Well, obviously, with blood. How has this blood got there? By the only possible means--that is, by direct link-up between opposing cut capillary ends, and this can be shown to occur microscopically. At about five days adequate venous return is established and the blue graft fades through lavender to pink. Successful use of either type of composite graft requires the most delicate technique as the viability of the graft is highly precarious. T h e split skin graft. This comes in two basic thicknesses, thin and thick. A small piece of skin for a finger tip can be cut from the dorsum of the left wrist when the early pinkness of the scar will be hidden by the wrist watch, but for a larger piece the opposite upper arm is best used, preferably the medial aspect, which is relatively hairless. If a thigh is used the patient is bedridden for some days; if the same arm as the inju,ry is used the slight venous engorgement caused by the bandaging of the donor site may result in haematoma under the graft. Vol. 2
No. 2 1970
113
The Free Gra[t--John R. Cobbett
While the graft is being cut the assistant should push the tissues of the arm up around the humerus (Fig. 4) to give a wide flat surface and not pinch all the tissue posteriorly to give a narrow firmer surface (Fig. 5). A very thin graft will tear on handling and is best spread on tulle gras, but any other is much easier to handle withou,t any backing. The graft may be sutured into position and the long ends of some of the sutures tied over a bolus of flavine wool or foam plastic to exert a little pressure on the graft. Pressure is not essential for success of a graft, but the dressing helps to prevent haematoma and to prevent a sideways shearing stress which would rupture developing capillaries. In small, isolated areas on a convex surface sterile adhesive tape can be used to fix the graft. This method of fixation is particularly useful in children or nervous adu,lts as, although a little local anaesthetic will be needed to take the graft, the injured area can be gently cleaned and the graft applied by this method without the need for any anaesthesia whatever and in my hands a ring block is an unpleasant procedure.
Fig. 4
Holding up the tissues around the forearm will give a wide flat surface.
Fig. 5 Pinching the tissues posteriorly gives a narrow firmer surface.
On a finger tip the use of a thin split skin graft takes advantage of its inherent powers of late contracture which will draw in surrounding skin with its normal sensation and result in only a small scarred graft remaining as an island in an area of normal finger tip skin. Where contracture may be a problem a thicker skin graft is used.
FREE <..---THINNER ,(~
G RAFT ~. THtCKER~ /
-,,%
Fig. 6 114
To illustrate the relative properties of thin and thick grafts. Vol. 2
No. 2
1970
The Free Gra[t--lohn R. Cobbett T h e whole thickness skin graft. I believe that there is very little place for this in the acute hand injury. To see why it is necessary to compare the merits and demerits of thin and thick skin (Fig. 6). The thinner the graft the more easily it survives on perfusion and hence the more easily it takes. The thinner the quicker the donor site heals. In the case of the whole thickness graft there is a secondary defect to deal with--perhaps by direct closure, but quite possibly by using a split thickness skin graft at the donor site. Conversely the thinner the graft the more it will later contract, the uglier it will look, the more easily will it be damaged by normal stresses.
e.-------------4>
Fig. 7 The flexor muscles are strong enough to prevent contracture of grafts on the dorsum. CONTRACTURE The flexor muscles of the hand are normally adequate to deal with contracture of a split thickness graft on the dorsum (Fig. 7) with certain exceptions in the case of burns. The extensors, however, are too weak to overcome the contracture of a split graft on the flexor surface of the hand. This difficu,lty can be partly avoided by splinting the fingers in extension for six to twelve weeks, but this is undesirable, at least in the adult. In the child the split grafts will not keep pace with growth and flexion contracture of the fingers will occur. A successful full thickness graft on the flexor surface of the hand would, therefore, be ideal from the point of view of late contracture. Unfortunately, the chances of successful take of a full thickness graft in wou,nds that we commonly see, are very poor. Use a split graft, accept temporary contracture and re-graft with whole thickness skin at your leisure, again as a cold case, under the best possible conditions. CONCLUSION This leads back to the moral of this article which is: unless you have special experience, or an open joint or tendon sheath, use a split skin graft as primary cover. Definitive reconstruction is far better done cold.
Vol. 2
No. 2
1970
115
THE
FREE GRAFT
J O H N R. COBBETT, East Grinstead A colleague of mine once wrote " A Surgical Registrar should be as familiar with taking a skin graft as he is with emergency craniotomy". I managed to persuade him, before publication, that the comparison was, perhaps, unfortunate. Apart from the comparison itself it'is an unfortunate statement as to most people it implies a degree of difficulty. Perhaps this is the major merit of the free skin graft. It is a quick and easy method out of trouble when there is a defect that will not close with primary suture. D I S A D V A N T A G E S O F FLAPS
A lost pedicle flap is disaster. The patient is left with a noticeable scar on some part of his anatomy, he remains unhealed and he is reluctant to undergo another similar procedure. If a skin graft does not take the only real loss is time of healing as the donor site will be self-healing with no eventual scar. Flaps raised from other parts of the body require careful planning. It is only too easy to cut a flap upside down or a little too short or a little too long. Any surgeon or, indeed, any nurse with a modern graft knife can cut a piece of skin big enough for a hand defect. So grafts are easy, but flaps are difficult. ADVANTAGES OF GRAFTS
To take and attach a free graft is a matter of minutes. Even the simplest distant flap will take a good hour by the time it has been planned, cut, sutured in place, immobilised and the secondary defect closed. So, grafts are quick, flaps are slow--and this may be important when the patient has multiple injuries. So if you have a contaminated wound, or little experience, or are short of time or are just plain doubtful abou,t what to do, put on a free split skin graft. A flap can be used as a secondary, cold, planned procedure if one is needed. Another benefit of the primary graft is that the period of immobilisation is comparatively short. If a flap is necessary it can be done as a cold case when the wounds are healed, when most traumatic oedema has settled and when movement has returned to the joints, under the best possible conditions. However, at least in theory a free graft will not take on a bare cortical bone, bare tendon or bare ligament. It will take on the loose aureolar tissue over ligament and tendon and it will take on periosteum. 1" PERFuSION 4,
Fig. 1 A free graft can survive by perfusion. 112
Vol. 2~
No. 2
1970
The Free Graft--John R. Cobbett
VASCULARISATION What is meant by "take" of a graft? In essence that the graft has become revascularised by the bed. Survival, as opposed to take, of a graft can happen in two ways. First it can live purely by perfu,sion between it and the bed (Fig. 1) and secondly, often much later, by being revascularised. Many grafts live by perfusion for a day or two before vascularisation occurs. Vascularisation itself can occur in two ways--first by gradual in-growth of capillary loops from the bed into the graft (Fig. 2) and secondly by direct anastomosis between cut capillaries in the bed and in the graft (Fig. 3). Obviously, over bare bone, tendon or ligament there is precious little to offer the graft, either by perfusion or by way of cut capillaries. Even in these circumstances the graft will act as a good temporary dressing over such structures and if the area is narrow enough, or small enough, may survive by the phenomenon of "bridging" whereby it received its blood supply from the neigh. bouring graft and hence lives over the avascular structure. So it may still be worth using a free graft even when one or more of these avascular structures form part of the bed. There must be one absolute contraindication though--never, ever, use a free skingraft across an open joint. M E T H O D S OF
SLOW ;~EVASCUL AR I SATION'
"'IMMEDIATE"
REVA SCULARtSATIOt,I
Fig. 2 Revascularisation may take place by ingrowth of capillary loops. Fig. 3 . . . or by direct anastomosis of capillaries. TYPES OF FREE G R A F T T h e composite graft. This is familiar to all as that fragment of finger tip that
has been washed in cetrimide and sewn back in place. It has full thickness skin plus some pulp. Hence "composite". Another form of composite graft is the immediate toe-pulp replacement of amputated finger tip. Composite grafts have an academic interest of their own. Immediately after operation the graft is deathly white. At six hours it is engorged and blue-black; engorged with what? Well, obviously, with blood. How has this blood got there? By the only possible means--that is, by direct link-up between opposing cut capillary ends, and this can be shown to occur microscopically. At about five days adequate venous return is established and the blue graft fades through lavender to pink. Successful use of either type of composite graft requires the most delicate technique as the viability of the graft is highly precarious. T h e split skin graft. This comes in two basic thicknesses, thin and thick. A small piece of skin for a finger tip can be cut from the dorsum of the left wrist when the early pinkness of the scar will be hidden by the wrist watch, but for a larger piece the opposite upper arm is best used, preferably the medial aspect, which is relatively hairless. If a thigh is used the patient is bedridden for some days; if the same arm as the inju,ry is used the slight venous engorgement caused by the bandaging of the donor site may result in haematoma under the graft. Vol. 2
No. 2 1970
113
The Free Gra[t--John R. Cobbett
While the graft is being cut the assistant should push the tissues of the arm up around the humerus (Fig. 4) to give a wide flat surface and not pinch all the tissue posteriorly to give a narrow firmer surface (Fig. 5). A very thin graft will tear on handling and is best spread on tulle gras, but any other is much easier to handle withou,t any backing. The graft may be sutured into position and the long ends of some of the sutures tied over a bolus of flavine wool or foam plastic to exert a little pressure on the graft. Pressure is not essential for success of a graft, but the dressing helps to prevent haematoma and to prevent a sideways shearing stress which would rupture developing capillaries. In small, isolated areas on a convex surface sterile adhesive tape can be used to fix the graft. This method of fixation is particularly useful in children or nervous adu,lts as, although a little local anaesthetic will be needed to take the graft, the injured area can be gently cleaned and the graft applied by this method without the need for any anaesthesia whatever and in my hands a ring block is an unpleasant procedure.
Fig. 4
Holding up the tissues around the forearm will give a wide flat surface.
Fig. 5 Pinching the tissues posteriorly gives a narrow firmer surface.
On a finger tip the use of a thin split skin graft takes advantage of its inherent powers of late contracture which will draw in surrounding skin with its normal sensation and result in only a small scarred graft remaining as an island in an area of normal finger tip skin. Where contracture may be a problem a thicker skin graft is used.
FREE <..---THINNER ,(~
G RAFT ~. THtCKER~ /
-,,%
Fig. 6 114
To illustrate the relative properties of thin and thick grafts. Vol. 2
No. 2
1970
The Free Gra[t--lohn R. Cobbett T h e whole thickness skin graft. I believe that there is very little place for this in the acute hand injury. To see why it is necessary to compare the merits and demerits of thin and thick skin (Fig. 6). The thinner the graft the more easily it survives on perfusion and hence the more easily it takes. The thinner the quicker the donor site heals. In the case of the whole thickness graft there is a secondary defect to deal with--perhaps by direct closure, but quite possibly by using a split thickness skin graft at the donor site. Conversely the thinner the graft the more it will later contract, the uglier it will look, the more easily will it be damaged by normal stresses.
e.-------------4>
Fig. 7 The flexor muscles are strong enough to prevent contracture of grafts on the dorsum. CONTRACTURE The flexor muscles of the hand are normally adequate to deal with contracture of a split thickness graft on the dorsum (Fig. 7) with certain exceptions in the case of burns. The extensors, however, are too weak to overcome the contracture of a split graft on the flexor surface of the hand. This difficu,lty can be partly avoided by splinting the fingers in extension for six to twelve weeks, but this is undesirable, at least in the adult. In the child the split grafts will not keep pace with growth and flexion contracture of the fingers will occur. A successful full thickness graft on the flexor surface of the hand would, therefore, be ideal from the point of view of late contracture. Unfortunately, the chances of successful take of a full thickness graft in wou,nds that we commonly see, are very poor. Use a split graft, accept temporary contracture and re-graft with whole thickness skin at your leisure, again as a cold case, under the best possible conditions. CONCLUSION This leads back to the moral of this article which is: unless you have special experience, or an open joint or tendon sheath, use a split skin graft as primary cover. Definitive reconstruction is far better done cold.
Vol. 2
No. 2
1970
115