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Failure of free muscle grafts in dogs
British Journal of Plastic Surgery (I976)~ "9, -'27-33
FAILURE OF FREE MUSCLE GRAFTS IN D O G S By A. C. H. WATSON,F.R.C.S. and A. R. MUIR, M.D.
Departments of Clinical Surgery and Veterinary Anatomy, University of Edinburgh THE first report of successful muscle grafting seems to have been that of Studitsky and Bosova (I96O) who transplanted part of the previously denervated gastrocnemius of the rat with histological proof of survival. In I971 Thompson published his preliminary experimental and clinical results and a number of other papers have followed (Thompson, I97Ia, b, c; Carlson and Gutmann, 1974; Freilinger et al., 1974; Hakelius et al., 1975). Thompson maintained that success could be achieved by preliminary denervation of the graft and by transferring the entire muscle to lie in intimate contact with a normally innervated muscle. Although his patients appeared to have been clinically improved, the evidence of functioning graft survival did not seem convincing in many cases. Moreover, analysis of his experimental results showed that, of 8 previously denervated grafts, fibrous tissue composed three-quarters or more of the surviving bulk in 4, and half the bulk in I. Only 3 muscles had more than 50 per cent of the surviving bulk composed of muscle fibres. We therefore felt that further experimental work was desirable, and designed a model in the dog which would fulfil the criteria Thompson had laid down and which would show not only whether there was survival of muscle but whether the muscle would function. TECHNIQUE The peroneus longus muscle which has a long tendon was chosen as the graft. At a preliminary operation it was denervated by dividing the easily accessible and identifiable branches of the common peroneal nerve which supply it. Denervation was confirmed with a nerve stimulator. Two to 3 weeks later the muscle was carefully excised and transplanted to the superficial surface of the gluteus medins. The overlying deep fascia was excised and elevated and the epimysium stripped from the surface of both muscles to allow direct contact between muscle fibres. There were 3 groups of dogs.
Group I (4 dogs). Both peroneus longus muscles were denervated at the first operation except for I dog in which I was left as a control. Two weeks later I of the denervated muscles (and the control) was taken for histological and histochemical examination. Denervation was confirmed histologically by a decrease in the size of muscle fibres compared with the intact muscle, by an increase in relative capillary density and by the failure to stain nerve fibres. At the same procedure the other muscle with its attached tendon was transplanted to the gluteus medius. It was placed at right-angles to the host muscle to prevent confusion between contraction of peroneus longus and gluteus medins and to allow the 2 muscles to be distinguished histologically. The tendon was passed through a hole in the deep fascia through a small tubed skin loop and sutured to itself under slight tension (Fig. I). The idea was that any developing ability of the graft to contract could be recorded by passing a blunt hook through the loop and connecting it to a recording device. After recovery the dogs were examined twice weekly for evidence of muscle function. The dog was supported on its hind legs to put both glutei into contraction. By 27
28
B R I T I S H JOURNAL OF PLASTIC SURGERY
lifting and flexing I leg at a time the muscle could be made to relax and contract and any movement of the graft or skin loop noted. After 5 to 6 months, at a terminal procedure, the cranial gluteal nerve was exposed and the nerve stimulator applied. Without disturbing the graft it was possible to
FIG. I. A, Diagram of graft of m. peroneus longus placed at right-angles to the fibres of m. gluteus medius near its origin, with the graft tendon passing through a skin loop. B, Skin loop.
obtain maximum contraction of the gluteus medius and assess movement of the skin loop. The skin was then reflected and the tendon dissected down to the muscle graft. Further stimulation studies were carried out and then the graft, with a block of underlying muscle, was taken for histological and histochemical examination. Results. At no time was there any clinical evidence of graft contraction or movement of the skin loop in any dog nor did stimulation of the cranial gluteal nerve produce any sign of graft contraction. However, it was interesting, and we believe very significant, that if the tendon was not exactly at right-angles to the fibres of the gluteus medius, the tendon would move and a very convincing illusion of graft contraction be obtained. On exposure the graft was found in each case to be shrunken and fibrosed. For histology, the specimens were cut in half at right-angles to the graft. Paraffin sections were stained with haematoxylin and Masson's Trichrome and frozen sections studied by the histochemical methods of Davies and Gunn (1962) for activity of succinic dehydrogenase, glycogen phosphatase and myosin ATPase. Possible surviving muscle fibres were found in only I animal, but even this was doubtful as the fibres retained the normal mosaic expected in regenerated, reinnervated muscle (Karpati and Engel, I968). It could be that these fibres represented a shred of gluteus medius lifted up with the deep fascia (Fig. 2). G r o u p 2 (4 dogs). The procedure was identical to that in Group I, except that no skin loop was created. The dogs were sacrificed at 4 days, 3 weeks, 6 weeks and 3 months respectively. No dynamic studies were carried out but the grafts were examined histologically. Results. At 4 days there was considerable oedema around the graft but no haematoma between it and its bed. Histological examination confirmed the close proximity
FAILURE OF FREE MUSCLE GRAFTS IN DOGS
FIG. 2. FIG. 3.
29
Graft with muscle fibres showing normal mosaic pattern with myosin ATPase stain.
Graft at 4 days showing lack of barrier to ingrowth of blood vessels or nerves. junction between graft and host muscle.
Arrow marks
FIG. 4. Graft at ~I days showing necrotic muscle, regenerating muscle fibres, and fibrous tissue. FIG. 5. Motor end plates in gluteus medius immediately beneath the graft.
30
BRITISH JOURNAL OF PLASTIC SURGERY
between host and graft with no significant barrier to the ingrowth of blood vessels or nerves (Fig. 3). At 3 weeks the graft showed a central core of necrotic muscle surrounded by whorled cellular connective tissue. Within this fibrous tissue small nests of cells could be identified as regenerating muscle fibres (Fig. 4). The grafts at 6 and I2 weeks were composed of the same dense fibrous tissue as seen in the first experimental group. In all cases the terminal ramifications of motor nerves could be demonstrated in the gluteus medius immediately underneath the transplanted muscle (Fig. 5). Although fine nerve fibres ran into the graft, often in company with blood vessels, no sign of collateral shoots from motor end plates was seen.
Group 3 (3 dogs). Three possible causes of failure of the grafts in Groups I and 2 were considered to be: the direction of the graft fibres compared with the host muscle; lack of significant tension; the bulk of the graft. In order to test these hypotheses, 3 dogs had both peroneus longus muscles transplanted, 3 weeks after denervation, to the superficial surfaces of the glutei, but with different combinations of the following variables: placed at right-angles or parallel to the host muscle (when the graft was placed parallel, an 8/0 nylon suture was woven backwards and forwards between graft and host to allow histological identification of the plane between them); sutured under tension either to the iliac crest at each end, or to the iliac crest and greater trochanter (depending on direction) or sutured as it lay without tension; left intact or split halfway through longitudinally and opened to allow a greater area of contact with the host muscle. The 6 grafts in this group together with the variation used in Groups I and 9 covered all possible combinations except a graft which was parallel, intact and under tension. In view of the consistent results with the other 7 combinations, this omission does not seem significant. The dogs were sacrificed between 5 and 6 months and the grafts examined as in the other groups. Results. Five of the 6 grafts were totally replaced by fibrous tissue. The 6th retained much of its original bulk but histological examination revealed only a few surviving muscle fibres at the periphery. The remainder of the graft showed fibrous tissue with extensive infiltration by inflammatory cells. There had been no clinical signs of infection. DISCUSSION
The total failure of all these muscle grafts is in marked contrast to other published results in spite of strict adherence to the principles outlined by Thompson. It is highly improbable that they were all due to technical errors and other explanations were sought. The survival of any graft depends on its acquiring an adequate blood supply before it dies of ischaemia and this in turn is related to the metabolic requirements of the graft, its vascularity, its bulk and the vascularity of its bed. It is mainly the demanding metabolism of muscle which has been the cause of its traditional failure as a graft, but under certain conditions it can be made to survive in the experimental animal (Studitsky, I964; Thompson, I97I; Carlson and Gutmann, I972, I974; Gutmann et aL, Freilinger et al., I974; Hakelius, I974). Denervation of a muscle induces several changes which might theoretically be
F A I L U R E OF FREE MUSCLE GRAFTS I N DOGS
31
expected to improve its survival as a graft. There is a significant decrease in the enzyme activity of its most active fibres (Romanul and Hogan, 1965) leading to a lowering of its metabolic requirements. There is a decrease in its bulk, a relative increase in the number of capillaries, and possibly also an absolute increase in their number for the first 2 weeks (Hakclius and Nystrom, 1975). Muscle can bc transplanted in the rat without previous interference as successfully as after denervation but prior denervation modifies the changes which take place in the graft. Graft survival is due to a process of degeneration followed by regeneration of most of the muscle fibres, a few peripheral ones surviving intact. After dencrvation the regeneration takes place more quickly throughout the muscle and more peripheral fibres survive (Carlson and Gutmann, 1974). Studitsky (1964) showed that dencrvation was only one of several forms of trauma such as mincing which enhanced the degeneration/ regeneration responses and suggests that all induce what hc terms a "plastic state" or de-differentiation of the muscle fibres which enhances its regenerative capacity. We have ample evidence that our grafts were denervated. Thompson suggests that the preservation of the entire muscle cell is of vital importance but he produces no evidence to support this contention. Indeed, Studitsky and Bosova (196o) reported success in the rat of transplanting the central third of the previously denervatcd gastrocncmius to a defect in the contralateral muscle. If survival is largely due to degeneration and regeneration then the integrity of the individual fibre cannot be important. Ncverthclcss, great care was taken in our experiments to fulfil this criterion of Thompson, except in those grafts which were laid open. Failure of our grafts could be attributed to their bulk. The peroneus longus of a 14 kg collie dog 3 weeks after denervation weighs approximately 3"5 g and is about o'75 cm thick; it is hard to conceive of such a mass of muscle tissue surviving other than by degeneration and regeneration. It is, however, smaller than the human palmaris longus and sartorius and comparable in size to the canine pronator tcres. Success has been claimed for grafts of all these muscles (Thompson, 1971; Hakelius, 1974). In any case, attempts to reduce the ischaemic volume of our grafts by splitting and laying them open were no more successful. Rapid reinncrvation of the muscle graft is considered an essential requisite for functional survival and for this reason efforts were made to remove all connective tissue between graft and gluteus medius. Histological studies showed that nerves and motor end platcs were present in relation to the grafts and that there were no significant barriers to their ingrowth, so this does not seem to bc the reason for failure. It is possible, however, that the number of nerve fibres and motor end plates, which varies from muscle to muscle, may bc significant. No attention has bccn paid to this factor hitherto. The vascularity of the gluteus mcdius is unlikely to bc less than that of other muscles and it should be able to nourish a graft on its surface equally well. The possibility of shearing between graft and the underlying contracting host muscle must be considered. All grafts were sutured into place and the transverse ones placed near the origin of the glutcus so that movement, though present, was not great. No difference was noted between the transverse and parallel grafts. No attempt was made to splint the leg postoperatively, but such precautions have not been a feature of other reports. Muscles atrophy following tenotomy. The possibility that a graft would have a greater chance of survival if sutured under tension was considered, but we failed to confirm this hypothesis. While suture of the transverse grafts to each end of the iliac crest was not comparable to the dynamic situation of an intact muscle, suturing of one end to the iliac crest and the other to the greater trochanter was, and only a few fibres
32
BRITISH JOURNAL OF P L A S T I C SURGERY
were found to survive. Little attention seems to have been paid to this aspect by other workers. I n reviewing our own work and comparing it with that of others, we have been unable to reach any firm conclusions w h y we have failed to reproduce their experimental results. T w o facts emerge however. T h e first is that most of the experimental work has been done on small animals and m u c h more study is required to determine the criteria necessary for success in the large animal and human. T h e second fact is the difficulty of proving successful functional survival in the human. Although some muscle grafts have apparently survived and become contractile there is as yet no p r o o f that this can be generally repeated. M a n y o f the reported clinical successes could be due equally well to the passive transmission o f movement from the recipient muscle that we were able to demonstrate so clearly. This in no way denigrates the usefulness o f the procedure for it m a y be that a fibrosed graft provides a better attachment to the motor muscle than could be obtained by simple suture o f a tendon or fascial strip. Until more information is available regarding the conditions necessary to produce functional survival o f a muscle graft in the human, we would suggest that attention in this direction would be more likely to produce positive results.
Professor A. R. Muir died shortly before this investigation was completed and the surviving author gratefully acknowledges the subsequent help he has received from Mr Michael Gunn of the Department of Veterinary Anatomy, University of Edinburgh and Dr Goldwyn Sclare and the technical staff of the Pathology Department, Bangour Hospital in the preparation and interpretation of histological material. He wouM also like to thank Mr Cumming of the Photography Department, Royal Hospital for Sick Children, Edinburgh for preparing the illustrations. Address for reprints: A. C. H. Watson, F.R.C.S., Consultant Plastic Surgeon, Royal Hospital for Sick Children, Sciennes Road, Edinburgh EH9 rLF. REFERENCES CARLSON,B. M. and GUTMANN,E. (1972). Development of contractile properties in minced muscle regenerates in the rat. ExperimentalNeurology, 36, 239. CARLSON,B. M. and GUTMANN,E. (I974). Transplantation and "cross transplantation" of free muscle grafts in the rat. Experimemia,3o (ii), 1292. DAVIES,A. S. and GUNN,H. M. (1972). Histochemical fibre types in mammalian muscle. Journal of Anatomy, 112, I, 41. FREILINGER,G., HOLLE, H. and MANCOLI,B. (1974). Free muscle transplants for anal sphincter reconstruction in pigs. Chirurgiaplastica (Berlin), 2, 133GUTMANN,E., HASEK,M. and CI-IUTNA,J. (1973). Muscleallografts in tolerant rats. Transplantation, 16, I, 73. HAKELIUS,L (1974). Transplantation of free autogenous muscle in the treatment of facial paralysis. ScandinavianJournal of Plastic and Reconstructive Surgery, 8, 220. I-IAKELIUS,L. and NYSTROM,B. (1975). Blood vessels and connective tissue in autotransplanted free muscle grafts of the cat. ScandinavianJournal of Plastic and Reconstructive Surgery (in press). HAKELIUS,L., NYSTROM,B. and STALBERG,E. (1975). Histochemical and neurophysiological studies of autotransplanted cat muscle. ScandinavianJournal of Plastic and
Reconstructive Surgery, 9, 15.
KARPATI,G. and ENGEL,W. K. (1968). "Type grouping" in skeletal muscles after experimental re-innervation. Neurology (Minneapolis), 18, 447. ROMANUL,E. C. A. and HOGAN,E. L. (I965). Enzymatic changes in denervated muscle. Archives of Neurology, I3, 263. STUOITSKY,A. N. and BOSOVA,N. N. (196o). The development of an atrophied muscle tissue in the conditions of a transplantation on the site of mechanically damaged muscles. Archiv Anatomii, Gistologiii Embryologii, 39 (I2), 18. STUDITSI~Y,A. N. (1964). Free auto and homografts of muscle tissue in experiments on animals. Annals of the New York Academy of Science, I2O, 789. THOMPSON,iXl.(I97Ia). Autogenous free grafts of skeletal muscles. Plasticand Reconstructive Surgery, 48, II.
FAILURE OF FREE MUSCLE GRAFTS IN DOGS THOMPSON, N. (I97Ib). Treatment of facial paralysis by free skeletal muscle grafts. I n "Transactions of the Fifth International Congress of Plastic Surgery", p. 66. Sydney, Australia: Butterworth. THOMPSON, N. (I97IC). Investigation of autogenous skeletal muscle free grafts in the dog. Transplantatio n , 12-5, 353.
29/1--8
33
FAILURE OF FREE MUSCLE GRAFTS IN D O G S By A. C. H. WATSON,F.R.C.S. and A. R. MUIR, M.D.
Departments of Clinical Surgery and Veterinary Anatomy, University of Edinburgh THE first report of successful muscle grafting seems to have been that of Studitsky and Bosova (I96O) who transplanted part of the previously denervated gastrocnemius of the rat with histological proof of survival. In I971 Thompson published his preliminary experimental and clinical results and a number of other papers have followed (Thompson, I97Ia, b, c; Carlson and Gutmann, 1974; Freilinger et al., 1974; Hakelius et al., 1975). Thompson maintained that success could be achieved by preliminary denervation of the graft and by transferring the entire muscle to lie in intimate contact with a normally innervated muscle. Although his patients appeared to have been clinically improved, the evidence of functioning graft survival did not seem convincing in many cases. Moreover, analysis of his experimental results showed that, of 8 previously denervated grafts, fibrous tissue composed three-quarters or more of the surviving bulk in 4, and half the bulk in I. Only 3 muscles had more than 50 per cent of the surviving bulk composed of muscle fibres. We therefore felt that further experimental work was desirable, and designed a model in the dog which would fulfil the criteria Thompson had laid down and which would show not only whether there was survival of muscle but whether the muscle would function. TECHNIQUE The peroneus longus muscle which has a long tendon was chosen as the graft. At a preliminary operation it was denervated by dividing the easily accessible and identifiable branches of the common peroneal nerve which supply it. Denervation was confirmed with a nerve stimulator. Two to 3 weeks later the muscle was carefully excised and transplanted to the superficial surface of the gluteus medins. The overlying deep fascia was excised and elevated and the epimysium stripped from the surface of both muscles to allow direct contact between muscle fibres. There were 3 groups of dogs.
Group I (4 dogs). Both peroneus longus muscles were denervated at the first operation except for I dog in which I was left as a control. Two weeks later I of the denervated muscles (and the control) was taken for histological and histochemical examination. Denervation was confirmed histologically by a decrease in the size of muscle fibres compared with the intact muscle, by an increase in relative capillary density and by the failure to stain nerve fibres. At the same procedure the other muscle with its attached tendon was transplanted to the gluteus medius. It was placed at right-angles to the host muscle to prevent confusion between contraction of peroneus longus and gluteus medins and to allow the 2 muscles to be distinguished histologically. The tendon was passed through a hole in the deep fascia through a small tubed skin loop and sutured to itself under slight tension (Fig. I). The idea was that any developing ability of the graft to contract could be recorded by passing a blunt hook through the loop and connecting it to a recording device. After recovery the dogs were examined twice weekly for evidence of muscle function. The dog was supported on its hind legs to put both glutei into contraction. By 27
28
B R I T I S H JOURNAL OF PLASTIC SURGERY
lifting and flexing I leg at a time the muscle could be made to relax and contract and any movement of the graft or skin loop noted. After 5 to 6 months, at a terminal procedure, the cranial gluteal nerve was exposed and the nerve stimulator applied. Without disturbing the graft it was possible to
FIG. I. A, Diagram of graft of m. peroneus longus placed at right-angles to the fibres of m. gluteus medius near its origin, with the graft tendon passing through a skin loop. B, Skin loop.
obtain maximum contraction of the gluteus medius and assess movement of the skin loop. The skin was then reflected and the tendon dissected down to the muscle graft. Further stimulation studies were carried out and then the graft, with a block of underlying muscle, was taken for histological and histochemical examination. Results. At no time was there any clinical evidence of graft contraction or movement of the skin loop in any dog nor did stimulation of the cranial gluteal nerve produce any sign of graft contraction. However, it was interesting, and we believe very significant, that if the tendon was not exactly at right-angles to the fibres of the gluteus medius, the tendon would move and a very convincing illusion of graft contraction be obtained. On exposure the graft was found in each case to be shrunken and fibrosed. For histology, the specimens were cut in half at right-angles to the graft. Paraffin sections were stained with haematoxylin and Masson's Trichrome and frozen sections studied by the histochemical methods of Davies and Gunn (1962) for activity of succinic dehydrogenase, glycogen phosphatase and myosin ATPase. Possible surviving muscle fibres were found in only I animal, but even this was doubtful as the fibres retained the normal mosaic expected in regenerated, reinnervated muscle (Karpati and Engel, I968). It could be that these fibres represented a shred of gluteus medius lifted up with the deep fascia (Fig. 2). G r o u p 2 (4 dogs). The procedure was identical to that in Group I, except that no skin loop was created. The dogs were sacrificed at 4 days, 3 weeks, 6 weeks and 3 months respectively. No dynamic studies were carried out but the grafts were examined histologically. Results. At 4 days there was considerable oedema around the graft but no haematoma between it and its bed. Histological examination confirmed the close proximity
FAILURE OF FREE MUSCLE GRAFTS IN DOGS
FIG. 2. FIG. 3.
29
Graft with muscle fibres showing normal mosaic pattern with myosin ATPase stain.
Graft at 4 days showing lack of barrier to ingrowth of blood vessels or nerves. junction between graft and host muscle.
Arrow marks
FIG. 4. Graft at ~I days showing necrotic muscle, regenerating muscle fibres, and fibrous tissue. FIG. 5. Motor end plates in gluteus medius immediately beneath the graft.
30
BRITISH JOURNAL OF PLASTIC SURGERY
between host and graft with no significant barrier to the ingrowth of blood vessels or nerves (Fig. 3). At 3 weeks the graft showed a central core of necrotic muscle surrounded by whorled cellular connective tissue. Within this fibrous tissue small nests of cells could be identified as regenerating muscle fibres (Fig. 4). The grafts at 6 and I2 weeks were composed of the same dense fibrous tissue as seen in the first experimental group. In all cases the terminal ramifications of motor nerves could be demonstrated in the gluteus medius immediately underneath the transplanted muscle (Fig. 5). Although fine nerve fibres ran into the graft, often in company with blood vessels, no sign of collateral shoots from motor end plates was seen.
Group 3 (3 dogs). Three possible causes of failure of the grafts in Groups I and 2 were considered to be: the direction of the graft fibres compared with the host muscle; lack of significant tension; the bulk of the graft. In order to test these hypotheses, 3 dogs had both peroneus longus muscles transplanted, 3 weeks after denervation, to the superficial surfaces of the glutei, but with different combinations of the following variables: placed at right-angles or parallel to the host muscle (when the graft was placed parallel, an 8/0 nylon suture was woven backwards and forwards between graft and host to allow histological identification of the plane between them); sutured under tension either to the iliac crest at each end, or to the iliac crest and greater trochanter (depending on direction) or sutured as it lay without tension; left intact or split halfway through longitudinally and opened to allow a greater area of contact with the host muscle. The 6 grafts in this group together with the variation used in Groups I and 9 covered all possible combinations except a graft which was parallel, intact and under tension. In view of the consistent results with the other 7 combinations, this omission does not seem significant. The dogs were sacrificed between 5 and 6 months and the grafts examined as in the other groups. Results. Five of the 6 grafts were totally replaced by fibrous tissue. The 6th retained much of its original bulk but histological examination revealed only a few surviving muscle fibres at the periphery. The remainder of the graft showed fibrous tissue with extensive infiltration by inflammatory cells. There had been no clinical signs of infection. DISCUSSION
The total failure of all these muscle grafts is in marked contrast to other published results in spite of strict adherence to the principles outlined by Thompson. It is highly improbable that they were all due to technical errors and other explanations were sought. The survival of any graft depends on its acquiring an adequate blood supply before it dies of ischaemia and this in turn is related to the metabolic requirements of the graft, its vascularity, its bulk and the vascularity of its bed. It is mainly the demanding metabolism of muscle which has been the cause of its traditional failure as a graft, but under certain conditions it can be made to survive in the experimental animal (Studitsky, I964; Thompson, I97I; Carlson and Gutmann, I972, I974; Gutmann et aL, Freilinger et al., I974; Hakelius, I974). Denervation of a muscle induces several changes which might theoretically be
F A I L U R E OF FREE MUSCLE GRAFTS I N DOGS
31
expected to improve its survival as a graft. There is a significant decrease in the enzyme activity of its most active fibres (Romanul and Hogan, 1965) leading to a lowering of its metabolic requirements. There is a decrease in its bulk, a relative increase in the number of capillaries, and possibly also an absolute increase in their number for the first 2 weeks (Hakclius and Nystrom, 1975). Muscle can bc transplanted in the rat without previous interference as successfully as after denervation but prior denervation modifies the changes which take place in the graft. Graft survival is due to a process of degeneration followed by regeneration of most of the muscle fibres, a few peripheral ones surviving intact. After dencrvation the regeneration takes place more quickly throughout the muscle and more peripheral fibres survive (Carlson and Gutmann, 1974). Studitsky (1964) showed that dencrvation was only one of several forms of trauma such as mincing which enhanced the degeneration/ regeneration responses and suggests that all induce what hc terms a "plastic state" or de-differentiation of the muscle fibres which enhances its regenerative capacity. We have ample evidence that our grafts were denervated. Thompson suggests that the preservation of the entire muscle cell is of vital importance but he produces no evidence to support this contention. Indeed, Studitsky and Bosova (196o) reported success in the rat of transplanting the central third of the previously denervatcd gastrocncmius to a defect in the contralateral muscle. If survival is largely due to degeneration and regeneration then the integrity of the individual fibre cannot be important. Ncverthclcss, great care was taken in our experiments to fulfil this criterion of Thompson, except in those grafts which were laid open. Failure of our grafts could be attributed to their bulk. The peroneus longus of a 14 kg collie dog 3 weeks after denervation weighs approximately 3"5 g and is about o'75 cm thick; it is hard to conceive of such a mass of muscle tissue surviving other than by degeneration and regeneration. It is, however, smaller than the human palmaris longus and sartorius and comparable in size to the canine pronator tcres. Success has been claimed for grafts of all these muscles (Thompson, 1971; Hakelius, 1974). In any case, attempts to reduce the ischaemic volume of our grafts by splitting and laying them open were no more successful. Rapid reinncrvation of the muscle graft is considered an essential requisite for functional survival and for this reason efforts were made to remove all connective tissue between graft and gluteus medius. Histological studies showed that nerves and motor end platcs were present in relation to the grafts and that there were no significant barriers to their ingrowth, so this does not seem to bc the reason for failure. It is possible, however, that the number of nerve fibres and motor end plates, which varies from muscle to muscle, may bc significant. No attention has bccn paid to this factor hitherto. The vascularity of the gluteus mcdius is unlikely to bc less than that of other muscles and it should be able to nourish a graft on its surface equally well. The possibility of shearing between graft and the underlying contracting host muscle must be considered. All grafts were sutured into place and the transverse ones placed near the origin of the glutcus so that movement, though present, was not great. No difference was noted between the transverse and parallel grafts. No attempt was made to splint the leg postoperatively, but such precautions have not been a feature of other reports. Muscles atrophy following tenotomy. The possibility that a graft would have a greater chance of survival if sutured under tension was considered, but we failed to confirm this hypothesis. While suture of the transverse grafts to each end of the iliac crest was not comparable to the dynamic situation of an intact muscle, suturing of one end to the iliac crest and the other to the greater trochanter was, and only a few fibres
32
BRITISH JOURNAL OF P L A S T I C SURGERY
were found to survive. Little attention seems to have been paid to this aspect by other workers. I n reviewing our own work and comparing it with that of others, we have been unable to reach any firm conclusions w h y we have failed to reproduce their experimental results. T w o facts emerge however. T h e first is that most of the experimental work has been done on small animals and m u c h more study is required to determine the criteria necessary for success in the large animal and human. T h e second fact is the difficulty of proving successful functional survival in the human. Although some muscle grafts have apparently survived and become contractile there is as yet no p r o o f that this can be generally repeated. M a n y o f the reported clinical successes could be due equally well to the passive transmission o f movement from the recipient muscle that we were able to demonstrate so clearly. This in no way denigrates the usefulness o f the procedure for it m a y be that a fibrosed graft provides a better attachment to the motor muscle than could be obtained by simple suture o f a tendon or fascial strip. Until more information is available regarding the conditions necessary to produce functional survival o f a muscle graft in the human, we would suggest that attention in this direction would be more likely to produce positive results.
Professor A. R. Muir died shortly before this investigation was completed and the surviving author gratefully acknowledges the subsequent help he has received from Mr Michael Gunn of the Department of Veterinary Anatomy, University of Edinburgh and Dr Goldwyn Sclare and the technical staff of the Pathology Department, Bangour Hospital in the preparation and interpretation of histological material. He wouM also like to thank Mr Cumming of the Photography Department, Royal Hospital for Sick Children, Edinburgh for preparing the illustrations. Address for reprints: A. C. H. Watson, F.R.C.S., Consultant Plastic Surgeon, Royal Hospital for Sick Children, Sciennes Road, Edinburgh EH9 rLF. REFERENCES CARLSON,B. M. and GUTMANN,E. (1972). Development of contractile properties in minced muscle regenerates in the rat. ExperimentalNeurology, 36, 239. CARLSON,B. M. and GUTMANN,E. (I974). Transplantation and "cross transplantation" of free muscle grafts in the rat. Experimemia,3o (ii), 1292. DAVIES,A. S. and GUNN,H. M. (1972). Histochemical fibre types in mammalian muscle. Journal of Anatomy, 112, I, 41. FREILINGER,G., HOLLE, H. and MANCOLI,B. (1974). Free muscle transplants for anal sphincter reconstruction in pigs. Chirurgiaplastica (Berlin), 2, 133GUTMANN,E., HASEK,M. and CI-IUTNA,J. (1973). Muscleallografts in tolerant rats. Transplantation, 16, I, 73. HAKELIUS,L (1974). Transplantation of free autogenous muscle in the treatment of facial paralysis. ScandinavianJournal of Plastic and Reconstructive Surgery, 8, 220. I-IAKELIUS,L. and NYSTROM,B. (1975). Blood vessels and connective tissue in autotransplanted free muscle grafts of the cat. ScandinavianJournal of Plastic and Reconstructive Surgery (in press). HAKELIUS,L., NYSTROM,B. and STALBERG,E. (1975). Histochemical and neurophysiological studies of autotransplanted cat muscle. ScandinavianJournal of Plastic and
Reconstructive Surgery, 9, 15.
KARPATI,G. and ENGEL,W. K. (1968). "Type grouping" in skeletal muscles after experimental re-innervation. Neurology (Minneapolis), 18, 447. ROMANUL,E. C. A. and HOGAN,E. L. (I965). Enzymatic changes in denervated muscle. Archives of Neurology, I3, 263. STUOITSKY,A. N. and BOSOVA,N. N. (196o). The development of an atrophied muscle tissue in the conditions of a transplantation on the site of mechanically damaged muscles. Archiv Anatomii, Gistologiii Embryologii, 39 (I2), 18. STUDITSI~Y,A. N. (1964). Free auto and homografts of muscle tissue in experiments on animals. Annals of the New York Academy of Science, I2O, 789. THOMPSON,iXl.(I97Ia). Autogenous free grafts of skeletal muscles. Plasticand Reconstructive Surgery, 48, II.
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