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The Use of Prosthetic Materials in the Repair of Hernias
The Use of Prosthetic Materials in the Repair of Hernias LEO M. ZIMMERMAN, M.D., F.A.C.S. *
Hernia is associated in the minds of many with weakness of the structures composing the abdominal walls, and recurrences after operation are frequently explained on the basis of "poor tissues." It is not surprising, therefore, that search has been made for materials to supplement the organic tissues and for techniques of reinforcing the indigenous musculofasciallayers. During the past half-century, a wide variety of biological and inorganic substances have been advocated and used as prostheses in the repair of various types of abdominal hernia. Among these have been fresh and preserved human and animal tissues and a large, and ever-increasing, variety of flosses and meshes of silk, metal, and plastic materials. From the welter of literature that has surrounded these efforts, there are few facts as to the frequency of the use of these supplements, and little agreement as to their successes or failures. That there is a place for prostheses in the armamentarium of the surgeon for use in hernia operations, few would deny. In my own opinion, there are certain hernias, notably of the large postoperative ventral variety, that would not be amenable to surgical correction without the use of some foreign reinforcing material. On the other hand, it appears equally certain that, in the hands of enthusiasts, prostheses are used far more frequently than the prevailing conditions demand. Furthermore, it is apparent that the implantation of prostheses has not proved the panacea that might have been anticipated. All authors report a certain percentage of recurrence, with or without preceding wound suppuration. It is also common knowledge that the incidence of complications, primarily those of rather unimportant fluid accumulations, is large; but also all too frequently, very disagreeable and often serious results have followed from their use. A crucial question in the evaluation of any therapeutic measure for the repair of hernia concerns the incidence of recurrence. The determination of this figure, in general, is extremely difficult, as is manifested *Professor of Surgery, Chicago Medical School; Senior Attending Surgeon, Michael Reese and Cook County Hospitals, Chicago, Illinois
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by the total lack of agreement as to the results obtained by various surgeons with any of the standard methods of operation. This difficulty hinges upon differences in the age and sex distribution of the patients, their social and occupational conditions, and very importantly, on the duration and accuracy of the follow-up. A particularly important and apparently irreconcilable reason for the divergent statistics which have recently been brought into focus (Brandon) is the lack of any absolute criteria as to what constitutes a recurrent hernia. This does not apply merely to the more or less semantic question of differentiation between reappearance of an original hernia or the development of a new one. Much more subtle and impossible of resolution is the lack of a sharp differentiation between relative weakness and actual herniation. The evaluation of the results of hernias repaired with the aid of prosthetic materials introduces an additional question. All authors state that the use of such ancillary substances is restricted to the "difficult" hernias and those particularly prone to recur. It is reasonable to expect a somewhat larger percentage of failures with any method in such cases. However, the criteria as to which hernias fall into this category vary greatly from person to person. As a result of all of these difficulties, plus the limited experience of individual surgeons with any one type of prosthesis, and the brief duration as yet available for followup, we are totally unable to accept as fact the rates of failure of these methods as compared with the traditional ones. Another interesting and important fact that is as yet unavailable from the published material is the degree to which foreign implants have been adopted by the surgical profession. There is no doubt that we are living in a gadget-oriented age, and hernial prostheses must be included within that designation. My personal opinion is that prostheses are being used and recommended far more frequently than is necessary or advisable. Until such time as the actual merits and disadvantages are deterinined by adequate follow-up studies, more rigid indications will be difficult to establish. Among the elements of confusion are the enthusiasms of those who promulgate the various methods and substances and the disinclination of the casual user to report the individual failures and disasters. One statistical study which throws some light on the overall frequency of employment of prostheses, and the criteria for their use, has been reported by Adler. This is based on a questionnaire sent to some 2000 surgeons. Two-thirds of those who replied reported some use of surgical meshes. They indicated that prosthetic materials had been employed in approximately 10 per cent of their hernia repairs. All stated that the repair included the use of prostheses in a larger percentage of incisional hernias than in those of the inguinal variety. This, of course, is to be expected because of the magnitude of the defects that frequently characterize this type of hernia. The total figures were: Number of hernias repaired Mesh used Percentage
INCISIONAL
INGUINAL
98,500 19,300 19.6%
276,300 17,500 6.3%
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The wide range in the frequency of the employment of prostheses by different surgeons is exemplified in a few of the published reports. R. S. Smith, addressing the Western Surgical Association, described his material based on 339 operations for hernia in which 108 or onethird had prosthetic adjuvants. Guy, in discussing this presentation, stated he utilized foreign materials in 302 of 1073 operations, an almost identical frequency. Other discussants included McVay, who used them in "less than 1 per cent of groin hernias," and Johnson, who used them in none. Adler quoted Koontz as having stated that he used tantalum mesh in 95 per cent of all large incisional hernia repairs.
CHOICE OF PROSTHETIC MATERIAL A wide variety of biological and synthetic materials have been used, as is stated above, to reinforce hernia repairs. Among the former are autologous, homologous, and heterologous transplants of fascias, skin, or dermis (skin from which the epidermis has been removed). Artificial materials include an extensive and constantly growing number of metallic and plastic meshes recommended for this purpose. Several factors must enter into the choice from this large number of available prosthetic substances. Among these are their tolerance by the tissues and fluids of the host, their initial and late strength, their ready availability and ease of handling, and eventually their tendency toward complications. Most important must be their lack of irritation or incompatibility, an aspect which has been widely studied, notably by Koontz and his co-workers. It must be recognized that, while all of the proposed implant materials are tolerated to a great degree, none is perfect. The continuing experimentation and promotion of new products is an expression of incomplete satisfaction with those presently available. Somewhat paradoxically, Koontz, who studied this aspect more extensively than anyone else, believed that a certain amount of irritation was desirable because it provoked connective tissue proliferation, which he considered an essential requirement in the late results. He preferred tantalum to stainless steel mesh because the latter was too inert.
Autologous Transplants From the standpoint of tissue tolerance, the one transplant that is superior to all others is that of tissue taken from the patient's own body. Of such, fascia lata strips and patches from the thigh have had the longest use and the widest application. The strips have lo&t favor because of their tendency to become attenuated, thus widening the interstices between them. The patch flaps, however, have given excellent service. The transplanted fascia survives in its new location and serves as an effective bulwark where the local tissues are inadequate. Other host tissues, which include skin or dermis, are also well tolerated, but pose other disadvantages. Both substances are expected to undergo metaplasia from their original structure to white connective tissue. Since the goal is to provide a firm sheet of fibrous tissue, it would
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appear that the immediate implantation of mature, firm fascia would obviate the necessity for this metabolic transformation. Skin implants buried in the tissues are subject to additional complications arising from continued activity of the sweat and sebaceous glands with the formation of cysts and other abnormal structures within the abdominal wall. The use of fascia lata does necessitate a second operative procedure and leaves a hiatus in the enveloping fascia of the thigh. However, for a patch adequate for hernia repairs, the secondary intervention is of no material significance. Furthermore, in most instances the defect becomes obliterated with new fibrous tissue, and disturbances from muscle herniation rarely occur. If very large patches are required for huge ventral hernias, they may become much more difficult to obtain.
Homologous Tissues Preserved cadaver tissues, including human skin and fascia, and certain esoteric substances such as aorta and dura mater have all been used with a considerable degree of success, particularly in the hands of those who have advanced them. Such homologous tissues face the fate of all transplants from the body of one person to that of another, namely, rejection. Probably because of the low metabolic activities of connective tissue structures, the rejection is much less violent than that observed in more highly vascular and more physiologically active organs. Nonetheless, the implant is, in time, slowly replaced by autologous fibrous tissue. The "creeping" replacement may not evoke sufficient inflammatory change to make itself known to the recipient. However, there is a considerable degree of tissue incompatibility which may increase the incidence of complication or result in some loss of strength of the transplant. The failure of survival of the graft, particularly in infected wounds, often necessitates its removal as a noxious foreign body. Preserved tissues of other animal species has now been virtually abandoned.
Artificial Materials A great impetus was given to the employment of foreign substances as prosthetic aids when tantalum mesh was introduced some two decades ago. This alloy was found to be nonirritating and well tolerated in the human body, and afforded a very strong reinforcement in hernial operations as well as in other fields of surgery. The early high expectations for its us~ in herniorraphy, however, have not been realized. Quite early, stainkss steel meshes became available at much lower cost with apparently equal merit. As the years went on, however, it became increasingly evident that the metals became friable and ultimately disintegrated. The scar tissue which developed through the growth of connective tissue fibers between the interstices of the mesh, like scar tissue in general, had a tendency to stretch and lose its value as a supporting structure. While the observations of these changes were being accumulated, a number of flexible synthetic meshes came into use, which have largely replaced the metals. They have been woven of single or mul-
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tiple filament fibers of Ivalon, Nylon, Dacron and other plastics into meshes of various textures. At the present moment, Marlex appears to be in greatest favor. It must be noted that the proponents of certain substances have displayed zeal worthy of Madison Avenue in promoting their product, with the apparent implication that reiteration rather than dispassionate experimentation and observation might determine the choice of a material to be used. These plastics are easy to handle and adapt themselves readily to the contours of the body. Furthermore, if they become displaced and enter the peritoneal cavity or come into proximity of important blood vessels, they are much less likely to produce serious injury. The complications specifically associated with the foreign implants constitute a major objection to their indiscriminate use. Here, again, actual statistical data are not available. There is no doubt, however, that serum accumulations and wound infections are much more frequent than in traditional suture hernial repairs. Furthermore, the presence of a foreign body in an infected wound adds immeasurably to the difficulty of combating the infection. It is significant that the advocates of various synthetic prostheses make claim that their product is tolerated in the presence of infection. As a result of infection in wounds containing foreign bodies, persistent draining sinuses are frequent. These often require multiple operations and eventual removal of all offending foreign bodies. Naturally, recurrences are more apt to occur in wounds so infected. It is not infrequent that only the removal of the offending body, which in itself is a difficult procedure in the presence of an inflammatory environment, will bring an end to these unpleasant complications. In an editorial, R. L. Maier stated: In the past few years, I have had occasion to reoperate on many patients who were unfortunate enough to have had some type of inert substance used in the repair of their hernias. Their recurrent hernias with multiple draining sinuses have presented real problems. After I have reoperated on these patients, I have invariably been convinced that the implants were not indicated in the first operation since it was possible to repair these recurrent hernias by using one of the conventional methods of repair. Sound surgical judgment is still the prime requisite of a good surgeon. It is my conviction that its absence has already been demonstrated in most of the patients who have come under my care following the use of these various implants and their indiscriminate use in the repair of hernias should be condemned.
And we can sympathize with the lament of Taylor and Jontz, who wrote: It is not our purpose to condemn all or any mesh used to support such wounds.
However, we cannot but wish with considerable feeling that he who placed the mesh originally would again be called upon to remove it if infection or recurrence should follow. If this were the case, much of the present enthusiasm for the use of foreign-body prostheses in repair of hernias would disappear. Certainly, to depend on foreign-body patches for these operations is to invite trouble and admit loss of faith in basic wound repair.
Comment The ultimate value of any addition to the armamentarium for hernial surgery depends on its long-term reliability and on the pos-
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sibilities of unfavorable results. Autogenous fascia, as was stated earlier, survives as such in its new location and its strength remains permanently undiminished. Furthermore, it does not act as a foreign body and wound healing is not impaired by its presence. Neither of these important qualities pertains to any of the other reinforcing materials. It is now recognized that not only do the metals become work-hardened, inflexible, and friable; they .also tend to become fragmented, with separation of the pieces. What is left essentially is scar tissue which, as has been pointed out, is unreliable as a hernial repair. It now becomes evident that a comparable type of deterioration occurs with the woven plastic meshes. The initial strength, which is often surprising in view of the light texture of the mesh, is gradually lost. The time required for its failure in the different meshes has not yet been determined. Nonetheless, if the tendency to weaken cannot be eliminated, the plastic meshes will fall far short of their ultimate goal. The final criterion as was stated above is the recurrence rate when artificial aids are used. Because of the difficulties enumerated above, in evaluating the statistics that are offered, one can only say at the present time that prostheses have not proved to be the final solution to the hernia problem.
THE REAL ROLE OF PROSTHESES IN HERNIA In approaching the question of the role of prostheses in the hernial armamentarium, certain f\lndamental truths must be kept in mind. The basis of hernial surgery, as of surgery in general, must rest upon the recognition of the underlying anatomical, physiological, and biological characteristics of the condition that is being surgically attacked. Furthermore, the established fundamental principles of surgical practice must be observed. No artificial supplements can be expected to replace these time-honored precepts. The author of this article has long sought to redirect the thinking of surgeons to the basic normal and pathological anatomy of hernia rather than toward specific operative techniques. The same effort applies to the current question as to the employment of prostheses in hernia repair. It is generally agreed that the indirect inguinal hernia owes its genesis to a persistence of the embryonic processus vaginalis testis. The primary component of the pathological changes, therefore, is the hernia sac. In the infant, this is the only deviation from the normal. In the older child and in the adult, as the result of pressure exerted on the margins of the abdominal inguinal ring, there is dilation of this orifice until it extends beyond the lower margin of the internal oblique muscle. The pathology, therefore, of the uncomplicated indirect inguinal hernia can be reduced to two deviations from the normal, the sac and the moderately dilated ring. Strength or weakness of the abdominal musculature plays little, if any, part in the causation of these hernias and, by the same token, reinforcement with the body's own tissues or by means of prosthetic materials should not be necessary in the repair of this form of hernia.
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The direct inguinal hernia, by contrast, is due primarily to weakness of the abdominal wall. It is important to recognize the precise nature and extent of this deficiency. We have shown over a period of many years that the fundamental anatomical variation which predisposes to direct hernia is a congenital absence of the lowermost portion of the internal oblique muscle or its aponeurosis. Here, also, the pathological changes can be reduced to two factors. First is the structural weakness due to the absence of the above-mentioned musculo-aponeurotic tissues. The second component is the yielding, stretching, attenuation and tearing of the posterior layer of the musculo-aponeurotic wall. This structure, commonly referred to in the surgical literature as transversalis fascia, is in actuality the aponeurosis of the transversus abdominis muscle. Not a very strong structure at best, it is incapable of permanently withstanding the intra-abdominal pressure without overlying muscle support. Repair of such hernias requires first the closure of this defect in the transversus aponeurosis and then a reinforcement of the posterior wall by some form of patch or flap. Whether this support is to be taken from adjacent tissues or whether it is to be sought in free transplants of biological or synthetic material becomes a matter of choice for the individual surgeon and in each specific case. In describing the anatomical changes in indirect hernia, the term uncomplicated was stressed. The congenital predisposition to these hernia varieties occurs so frequently that both often exist in the same individual. Thus, there may be actual or potential direct hernia in addition to the indirect one for which operation is being done. Also, very large, long-standing, indirect hernias may sufficiently damage the entire parietal wall as to produce, in effect, a secondary posterior wall deficiency. In all such cases, posterior wall restoration and reinforcement must be added to the manipulations required for the repair of the indirect hernia. Conceivably, then, prostheses might be used under these conditions. From what has been said, it is evident that I do not favor wholesale or indiscriminate use of prostheses. In my own work, I use them rarely and only in response to specific indications. Inguinal hernias, though they may attain great dimensions, always emerge through a relatively narrow space, which has been designated the inguinal triangle(Fig. 1). This is the area bounded above by the lowermost fibers of the internal oblique muscle, by the edge of the rectus medially, and the inguinal ligament laterally. All inguinal hernias emerge through this space. For so limited an area, adequate repair is almost invariably feasible by utilization of the adjacent structures, and without recourse to foreign implants. Therefore, in primary inguinal hernias, I virtually never use prostheses. In recurrent hernias, particularly where there have been multiple operations, I have used free implants in a small number of cases, usually patches of fascia lata. These have served me well. The technique of free transplantation of fascia lata is very simple, and requires very little more than does a local suture operation (Fig. 2). The thigh on the side of the hernia is prepared and draped before operation. After the completion of the inguinal dissection and whatever local
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Figure 1. A, Inguinal triangle with well-developed intemal oblique muscle and no predisposition to direct hernia. B, Inguinal triangle in abdomens likely to develop direct hernia. (From Zimmerman, SURG. CLIN. N. AMER., 32:135-153, 1952.)
tissue repair is possible, a vertical incision is made on the outer aspect of the thigh. The skin flaps are reflected sufficiently to expose a suitable width of fascia lata, and an oval or rectangular patch of fascia is removed. No attempt is made to close the defect left in the fascia lata, but the edges of the defect are sutured to the subjacent muscle with interrupted sutures of fine silk to prevent further retraction. The transplant is then sutured in position, again with fine, nonabsorbable suture
Figure 2. Free transplant of fascia lata for repair of inquinal hemia. A, Incision on outer aspect of thigh. B, Removal of patch of fascia lata. C, Suture of margins of fascial defect to subjacent muscles. D, Graft applied over transversalis fascia. (From Zimmerman and Anson, Anatomy and Surgery of Hemia, Baltimore, Williams & Wilkins Co., 1953.)
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material. The graft should be placed in immediate apposition with the layer to be reinforced, without interposed fat, muscle, or cord structures. The one unequivocal indication for prostheses in hernia surgery is the large, postoperative, ventral defect which may attain enormous dimensions. Smaller hernias which can be adequately repaired by suture techniques of whatever variety, are better handled without the foreign substances. In the massive ones (Figs. 3, 4), where the edges of the
Figure 3. Above, Gigantic postoperative hernia. Below, Repair with tantalum gauze. (From Zimmerman and Anson, Anatomy and Surgery of Hernia, Baltimore, Williams & Wilkins Co., 1953.)
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Figure 4. Above, Large incisional hernia. Below, Same hernia repaired by combined suture and fascia lata transplant. (From Zimmerman and Anson, Anatomy and Surgery of Hernia, Baltimore, Williams & Wilkins Co., 1953.)
defect cannot be approximated or, at best, can be brought together only under degrees of tension that almost certainly foreshadow early recurrence, the introduction of a sheet of metallic or plastic mesh may resolve the problem. The synthetic implants are to be preferred instead of autogenous fascia lata because the very magnitude of the patch required would necessitate multiple or extensive dissections of the thigh in order to obtain a graft adequate for this purpose. In operations of this kind,
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it is my practice to close the upper and lower ends of the defect by suture as far as can be achieved without tension. From this point on, a relatively small piece of mesh suffices to close the entire defect. The mesh is usually brought below the edges of the defect and sutured into place with mattress stitches of either silk or of the material from which the mesh is woven.
SUMMARY The use of artificial materials in the repair of hernia has created an interest and evoked a literature which probably exceeds the importance of this innovation. From this chaotic volume, numerous materials and various techniques have been, and continue to be, promulgated but few factual conclusions can be drawn. There are, as yet, no reliable statistics as to the frequency with which such substances are currently being employed and no definite figures as to the complications or the recurrences which follow in their train. These deficiencies render informed indications difficult to establish. Of the many materials that have been advocated, autogenous fascia lata would appear to possess the most desirable qualities. The woven plastic meshes seem to be favored among the artificial devices. All of these are associated with complications in greater frequency and variety than are encountered with the traditional suture methods of operation. Furthermore, they have not furnished the ultimate solution for the hernia problem. While the incidence of recurrences is as yet unknown, failures have been reported with all of these surgical adjuvants and it now appears that all tend to fracture or weaken with the passage of time. Prostheses, whatever their value, cannot replace a full knowledge of the underlying anatomy and pathology of hernia, or substitute for the exercise of the time-honored principles of surgical technique. They are apparently being used more frequently and with less selectivity than the nature of the lesion demands. In my own opinion, such surgical aids are virtually never required in primary inguinal or femoral hernias. Following multiple recurrences, they may occasionally be indicated. Their real sphere of usefulness is in the mammoth-sized postoperative ventral hernia which otherwise might not be at all operable. Prostheses have not proved to be the ultimate solution to the hernia problem and only time will tell when and how often they should be used and what may be expected therefrom.
REFERENCES 1. Adler, R. H.: An evaluation of surgical mesh in the repair of hernias and tissue defects. Arch. Surg., 85:836-844, 1962. 2. Brandon, W. j. M.: Inguinal hernia. The unpredictable result. Brit. J. Surg., 34:14-18, 1946. 3. Guy, C. C.: Discussion of paper by R. S. Smith. 4. Guy, C. C., Werelius, C. Y., and Bell, L. B.: Five years' experience with tantalum mesh in hernia repair. SURG. CLIN. N. AMER., 35:175-188, 1955. 5. Johnson, C. G.: Discussion of paper by R. S. Smith. 6. Koontz, A. R.: Hernia. New York, Appleton-Century-Crofts, 1963. 7. Maier, R. L.: Use and abuse of inert materials in hernia repairs (Editorial). Amer. J, Surg., 94:1, 1957.
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8. McVay, C.: Discussion of paper by R. S. Smith. 9. Smith, R. S.: !\djuncts in hernial repair. Arch. Surg., 78:868-875, 1959. 10. Smith, R. S.: Use of _;;tdjuncts in hernia repair: Basic principles. In Hernia (L. M. Nyhus and H. N. Harkins, Eds.). Philadelphia, J. B. Uppincott Co., 1964. 11. Taylor, F. W., and Jontz, J. G.: Incisional hernia repair. Surgery, 48:528-533, 1960. 12. Usher, F. C.: Hernia repair with Marlex mesh. In Hernia (L. M. Nyhus and H. N. Harkins, Eds.). Philadelphia, J. B. Uppincott Co., 1964. 13. Zimmerman, L. M.: Recent advances in surgery of inguinal hernia. SuRG. CLIN. N. AMER., 32:135-153, 1952. 14. Zimmerman, L. M., and Anson, B. J.: Anatomy and Surgery of Hernia. Baltimore, Williams & Wilkins Co., 1953. Second edition in press. 55 East Washington Street Chicago, Illinois 60602
Hernia is associated in the minds of many with weakness of the structures composing the abdominal walls, and recurrences after operation are frequently explained on the basis of "poor tissues." It is not surprising, therefore, that search has been made for materials to supplement the organic tissues and for techniques of reinforcing the indigenous musculofasciallayers. During the past half-century, a wide variety of biological and inorganic substances have been advocated and used as prostheses in the repair of various types of abdominal hernia. Among these have been fresh and preserved human and animal tissues and a large, and ever-increasing, variety of flosses and meshes of silk, metal, and plastic materials. From the welter of literature that has surrounded these efforts, there are few facts as to the frequency of the use of these supplements, and little agreement as to their successes or failures. That there is a place for prostheses in the armamentarium of the surgeon for use in hernia operations, few would deny. In my own opinion, there are certain hernias, notably of the large postoperative ventral variety, that would not be amenable to surgical correction without the use of some foreign reinforcing material. On the other hand, it appears equally certain that, in the hands of enthusiasts, prostheses are used far more frequently than the prevailing conditions demand. Furthermore, it is apparent that the implantation of prostheses has not proved the panacea that might have been anticipated. All authors report a certain percentage of recurrence, with or without preceding wound suppuration. It is also common knowledge that the incidence of complications, primarily those of rather unimportant fluid accumulations, is large; but also all too frequently, very disagreeable and often serious results have followed from their use. A crucial question in the evaluation of any therapeutic measure for the repair of hernia concerns the incidence of recurrence. The determination of this figure, in general, is extremely difficult, as is manifested *Professor of Surgery, Chicago Medical School; Senior Attending Surgeon, Michael Reese and Cook County Hospitals, Chicago, Illinois
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by the total lack of agreement as to the results obtained by various surgeons with any of the standard methods of operation. This difficulty hinges upon differences in the age and sex distribution of the patients, their social and occupational conditions, and very importantly, on the duration and accuracy of the follow-up. A particularly important and apparently irreconcilable reason for the divergent statistics which have recently been brought into focus (Brandon) is the lack of any absolute criteria as to what constitutes a recurrent hernia. This does not apply merely to the more or less semantic question of differentiation between reappearance of an original hernia or the development of a new one. Much more subtle and impossible of resolution is the lack of a sharp differentiation between relative weakness and actual herniation. The evaluation of the results of hernias repaired with the aid of prosthetic materials introduces an additional question. All authors state that the use of such ancillary substances is restricted to the "difficult" hernias and those particularly prone to recur. It is reasonable to expect a somewhat larger percentage of failures with any method in such cases. However, the criteria as to which hernias fall into this category vary greatly from person to person. As a result of all of these difficulties, plus the limited experience of individual surgeons with any one type of prosthesis, and the brief duration as yet available for followup, we are totally unable to accept as fact the rates of failure of these methods as compared with the traditional ones. Another interesting and important fact that is as yet unavailable from the published material is the degree to which foreign implants have been adopted by the surgical profession. There is no doubt that we are living in a gadget-oriented age, and hernial prostheses must be included within that designation. My personal opinion is that prostheses are being used and recommended far more frequently than is necessary or advisable. Until such time as the actual merits and disadvantages are deterinined by adequate follow-up studies, more rigid indications will be difficult to establish. Among the elements of confusion are the enthusiasms of those who promulgate the various methods and substances and the disinclination of the casual user to report the individual failures and disasters. One statistical study which throws some light on the overall frequency of employment of prostheses, and the criteria for their use, has been reported by Adler. This is based on a questionnaire sent to some 2000 surgeons. Two-thirds of those who replied reported some use of surgical meshes. They indicated that prosthetic materials had been employed in approximately 10 per cent of their hernia repairs. All stated that the repair included the use of prostheses in a larger percentage of incisional hernias than in those of the inguinal variety. This, of course, is to be expected because of the magnitude of the defects that frequently characterize this type of hernia. The total figures were: Number of hernias repaired Mesh used Percentage
INCISIONAL
INGUINAL
98,500 19,300 19.6%
276,300 17,500 6.3%
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The wide range in the frequency of the employment of prostheses by different surgeons is exemplified in a few of the published reports. R. S. Smith, addressing the Western Surgical Association, described his material based on 339 operations for hernia in which 108 or onethird had prosthetic adjuvants. Guy, in discussing this presentation, stated he utilized foreign materials in 302 of 1073 operations, an almost identical frequency. Other discussants included McVay, who used them in "less than 1 per cent of groin hernias," and Johnson, who used them in none. Adler quoted Koontz as having stated that he used tantalum mesh in 95 per cent of all large incisional hernia repairs.
CHOICE OF PROSTHETIC MATERIAL A wide variety of biological and synthetic materials have been used, as is stated above, to reinforce hernia repairs. Among the former are autologous, homologous, and heterologous transplants of fascias, skin, or dermis (skin from which the epidermis has been removed). Artificial materials include an extensive and constantly growing number of metallic and plastic meshes recommended for this purpose. Several factors must enter into the choice from this large number of available prosthetic substances. Among these are their tolerance by the tissues and fluids of the host, their initial and late strength, their ready availability and ease of handling, and eventually their tendency toward complications. Most important must be their lack of irritation or incompatibility, an aspect which has been widely studied, notably by Koontz and his co-workers. It must be recognized that, while all of the proposed implant materials are tolerated to a great degree, none is perfect. The continuing experimentation and promotion of new products is an expression of incomplete satisfaction with those presently available. Somewhat paradoxically, Koontz, who studied this aspect more extensively than anyone else, believed that a certain amount of irritation was desirable because it provoked connective tissue proliferation, which he considered an essential requirement in the late results. He preferred tantalum to stainless steel mesh because the latter was too inert.
Autologous Transplants From the standpoint of tissue tolerance, the one transplant that is superior to all others is that of tissue taken from the patient's own body. Of such, fascia lata strips and patches from the thigh have had the longest use and the widest application. The strips have lo&t favor because of their tendency to become attenuated, thus widening the interstices between them. The patch flaps, however, have given excellent service. The transplanted fascia survives in its new location and serves as an effective bulwark where the local tissues are inadequate. Other host tissues, which include skin or dermis, are also well tolerated, but pose other disadvantages. Both substances are expected to undergo metaplasia from their original structure to white connective tissue. Since the goal is to provide a firm sheet of fibrous tissue, it would
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appear that the immediate implantation of mature, firm fascia would obviate the necessity for this metabolic transformation. Skin implants buried in the tissues are subject to additional complications arising from continued activity of the sweat and sebaceous glands with the formation of cysts and other abnormal structures within the abdominal wall. The use of fascia lata does necessitate a second operative procedure and leaves a hiatus in the enveloping fascia of the thigh. However, for a patch adequate for hernia repairs, the secondary intervention is of no material significance. Furthermore, in most instances the defect becomes obliterated with new fibrous tissue, and disturbances from muscle herniation rarely occur. If very large patches are required for huge ventral hernias, they may become much more difficult to obtain.
Homologous Tissues Preserved cadaver tissues, including human skin and fascia, and certain esoteric substances such as aorta and dura mater have all been used with a considerable degree of success, particularly in the hands of those who have advanced them. Such homologous tissues face the fate of all transplants from the body of one person to that of another, namely, rejection. Probably because of the low metabolic activities of connective tissue structures, the rejection is much less violent than that observed in more highly vascular and more physiologically active organs. Nonetheless, the implant is, in time, slowly replaced by autologous fibrous tissue. The "creeping" replacement may not evoke sufficient inflammatory change to make itself known to the recipient. However, there is a considerable degree of tissue incompatibility which may increase the incidence of complication or result in some loss of strength of the transplant. The failure of survival of the graft, particularly in infected wounds, often necessitates its removal as a noxious foreign body. Preserved tissues of other animal species has now been virtually abandoned.
Artificial Materials A great impetus was given to the employment of foreign substances as prosthetic aids when tantalum mesh was introduced some two decades ago. This alloy was found to be nonirritating and well tolerated in the human body, and afforded a very strong reinforcement in hernial operations as well as in other fields of surgery. The early high expectations for its us~ in herniorraphy, however, have not been realized. Quite early, stainkss steel meshes became available at much lower cost with apparently equal merit. As the years went on, however, it became increasingly evident that the metals became friable and ultimately disintegrated. The scar tissue which developed through the growth of connective tissue fibers between the interstices of the mesh, like scar tissue in general, had a tendency to stretch and lose its value as a supporting structure. While the observations of these changes were being accumulated, a number of flexible synthetic meshes came into use, which have largely replaced the metals. They have been woven of single or mul-
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tiple filament fibers of Ivalon, Nylon, Dacron and other plastics into meshes of various textures. At the present moment, Marlex appears to be in greatest favor. It must be noted that the proponents of certain substances have displayed zeal worthy of Madison Avenue in promoting their product, with the apparent implication that reiteration rather than dispassionate experimentation and observation might determine the choice of a material to be used. These plastics are easy to handle and adapt themselves readily to the contours of the body. Furthermore, if they become displaced and enter the peritoneal cavity or come into proximity of important blood vessels, they are much less likely to produce serious injury. The complications specifically associated with the foreign implants constitute a major objection to their indiscriminate use. Here, again, actual statistical data are not available. There is no doubt, however, that serum accumulations and wound infections are much more frequent than in traditional suture hernial repairs. Furthermore, the presence of a foreign body in an infected wound adds immeasurably to the difficulty of combating the infection. It is significant that the advocates of various synthetic prostheses make claim that their product is tolerated in the presence of infection. As a result of infection in wounds containing foreign bodies, persistent draining sinuses are frequent. These often require multiple operations and eventual removal of all offending foreign bodies. Naturally, recurrences are more apt to occur in wounds so infected. It is not infrequent that only the removal of the offending body, which in itself is a difficult procedure in the presence of an inflammatory environment, will bring an end to these unpleasant complications. In an editorial, R. L. Maier stated: In the past few years, I have had occasion to reoperate on many patients who were unfortunate enough to have had some type of inert substance used in the repair of their hernias. Their recurrent hernias with multiple draining sinuses have presented real problems. After I have reoperated on these patients, I have invariably been convinced that the implants were not indicated in the first operation since it was possible to repair these recurrent hernias by using one of the conventional methods of repair. Sound surgical judgment is still the prime requisite of a good surgeon. It is my conviction that its absence has already been demonstrated in most of the patients who have come under my care following the use of these various implants and their indiscriminate use in the repair of hernias should be condemned.
And we can sympathize with the lament of Taylor and Jontz, who wrote: It is not our purpose to condemn all or any mesh used to support such wounds.
However, we cannot but wish with considerable feeling that he who placed the mesh originally would again be called upon to remove it if infection or recurrence should follow. If this were the case, much of the present enthusiasm for the use of foreign-body prostheses in repair of hernias would disappear. Certainly, to depend on foreign-body patches for these operations is to invite trouble and admit loss of faith in basic wound repair.
Comment The ultimate value of any addition to the armamentarium for hernial surgery depends on its long-term reliability and on the pos-
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sibilities of unfavorable results. Autogenous fascia, as was stated earlier, survives as such in its new location and its strength remains permanently undiminished. Furthermore, it does not act as a foreign body and wound healing is not impaired by its presence. Neither of these important qualities pertains to any of the other reinforcing materials. It is now recognized that not only do the metals become work-hardened, inflexible, and friable; they .also tend to become fragmented, with separation of the pieces. What is left essentially is scar tissue which, as has been pointed out, is unreliable as a hernial repair. It now becomes evident that a comparable type of deterioration occurs with the woven plastic meshes. The initial strength, which is often surprising in view of the light texture of the mesh, is gradually lost. The time required for its failure in the different meshes has not yet been determined. Nonetheless, if the tendency to weaken cannot be eliminated, the plastic meshes will fall far short of their ultimate goal. The final criterion as was stated above is the recurrence rate when artificial aids are used. Because of the difficulties enumerated above, in evaluating the statistics that are offered, one can only say at the present time that prostheses have not proved to be the final solution to the hernia problem.
THE REAL ROLE OF PROSTHESES IN HERNIA In approaching the question of the role of prostheses in the hernial armamentarium, certain f\lndamental truths must be kept in mind. The basis of hernial surgery, as of surgery in general, must rest upon the recognition of the underlying anatomical, physiological, and biological characteristics of the condition that is being surgically attacked. Furthermore, the established fundamental principles of surgical practice must be observed. No artificial supplements can be expected to replace these time-honored precepts. The author of this article has long sought to redirect the thinking of surgeons to the basic normal and pathological anatomy of hernia rather than toward specific operative techniques. The same effort applies to the current question as to the employment of prostheses in hernia repair. It is generally agreed that the indirect inguinal hernia owes its genesis to a persistence of the embryonic processus vaginalis testis. The primary component of the pathological changes, therefore, is the hernia sac. In the infant, this is the only deviation from the normal. In the older child and in the adult, as the result of pressure exerted on the margins of the abdominal inguinal ring, there is dilation of this orifice until it extends beyond the lower margin of the internal oblique muscle. The pathology, therefore, of the uncomplicated indirect inguinal hernia can be reduced to two deviations from the normal, the sac and the moderately dilated ring. Strength or weakness of the abdominal musculature plays little, if any, part in the causation of these hernias and, by the same token, reinforcement with the body's own tissues or by means of prosthetic materials should not be necessary in the repair of this form of hernia.
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The direct inguinal hernia, by contrast, is due primarily to weakness of the abdominal wall. It is important to recognize the precise nature and extent of this deficiency. We have shown over a period of many years that the fundamental anatomical variation which predisposes to direct hernia is a congenital absence of the lowermost portion of the internal oblique muscle or its aponeurosis. Here, also, the pathological changes can be reduced to two factors. First is the structural weakness due to the absence of the above-mentioned musculo-aponeurotic tissues. The second component is the yielding, stretching, attenuation and tearing of the posterior layer of the musculo-aponeurotic wall. This structure, commonly referred to in the surgical literature as transversalis fascia, is in actuality the aponeurosis of the transversus abdominis muscle. Not a very strong structure at best, it is incapable of permanently withstanding the intra-abdominal pressure without overlying muscle support. Repair of such hernias requires first the closure of this defect in the transversus aponeurosis and then a reinforcement of the posterior wall by some form of patch or flap. Whether this support is to be taken from adjacent tissues or whether it is to be sought in free transplants of biological or synthetic material becomes a matter of choice for the individual surgeon and in each specific case. In describing the anatomical changes in indirect hernia, the term uncomplicated was stressed. The congenital predisposition to these hernia varieties occurs so frequently that both often exist in the same individual. Thus, there may be actual or potential direct hernia in addition to the indirect one for which operation is being done. Also, very large, long-standing, indirect hernias may sufficiently damage the entire parietal wall as to produce, in effect, a secondary posterior wall deficiency. In all such cases, posterior wall restoration and reinforcement must be added to the manipulations required for the repair of the indirect hernia. Conceivably, then, prostheses might be used under these conditions. From what has been said, it is evident that I do not favor wholesale or indiscriminate use of prostheses. In my own work, I use them rarely and only in response to specific indications. Inguinal hernias, though they may attain great dimensions, always emerge through a relatively narrow space, which has been designated the inguinal triangle(Fig. 1). This is the area bounded above by the lowermost fibers of the internal oblique muscle, by the edge of the rectus medially, and the inguinal ligament laterally. All inguinal hernias emerge through this space. For so limited an area, adequate repair is almost invariably feasible by utilization of the adjacent structures, and without recourse to foreign implants. Therefore, in primary inguinal hernias, I virtually never use prostheses. In recurrent hernias, particularly where there have been multiple operations, I have used free implants in a small number of cases, usually patches of fascia lata. These have served me well. The technique of free transplantation of fascia lata is very simple, and requires very little more than does a local suture operation (Fig. 2). The thigh on the side of the hernia is prepared and draped before operation. After the completion of the inguinal dissection and whatever local
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Figure 1. A, Inguinal triangle with well-developed intemal oblique muscle and no predisposition to direct hernia. B, Inguinal triangle in abdomens likely to develop direct hernia. (From Zimmerman, SURG. CLIN. N. AMER., 32:135-153, 1952.)
tissue repair is possible, a vertical incision is made on the outer aspect of the thigh. The skin flaps are reflected sufficiently to expose a suitable width of fascia lata, and an oval or rectangular patch of fascia is removed. No attempt is made to close the defect left in the fascia lata, but the edges of the defect are sutured to the subjacent muscle with interrupted sutures of fine silk to prevent further retraction. The transplant is then sutured in position, again with fine, nonabsorbable suture
Figure 2. Free transplant of fascia lata for repair of inquinal hemia. A, Incision on outer aspect of thigh. B, Removal of patch of fascia lata. C, Suture of margins of fascial defect to subjacent muscles. D, Graft applied over transversalis fascia. (From Zimmerman and Anson, Anatomy and Surgery of Hemia, Baltimore, Williams & Wilkins Co., 1953.)
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material. The graft should be placed in immediate apposition with the layer to be reinforced, without interposed fat, muscle, or cord structures. The one unequivocal indication for prostheses in hernia surgery is the large, postoperative, ventral defect which may attain enormous dimensions. Smaller hernias which can be adequately repaired by suture techniques of whatever variety, are better handled without the foreign substances. In the massive ones (Figs. 3, 4), where the edges of the
Figure 3. Above, Gigantic postoperative hernia. Below, Repair with tantalum gauze. (From Zimmerman and Anson, Anatomy and Surgery of Hernia, Baltimore, Williams & Wilkins Co., 1953.)
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Figure 4. Above, Large incisional hernia. Below, Same hernia repaired by combined suture and fascia lata transplant. (From Zimmerman and Anson, Anatomy and Surgery of Hernia, Baltimore, Williams & Wilkins Co., 1953.)
defect cannot be approximated or, at best, can be brought together only under degrees of tension that almost certainly foreshadow early recurrence, the introduction of a sheet of metallic or plastic mesh may resolve the problem. The synthetic implants are to be preferred instead of autogenous fascia lata because the very magnitude of the patch required would necessitate multiple or extensive dissections of the thigh in order to obtain a graft adequate for this purpose. In operations of this kind,
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it is my practice to close the upper and lower ends of the defect by suture as far as can be achieved without tension. From this point on, a relatively small piece of mesh suffices to close the entire defect. The mesh is usually brought below the edges of the defect and sutured into place with mattress stitches of either silk or of the material from which the mesh is woven.
SUMMARY The use of artificial materials in the repair of hernia has created an interest and evoked a literature which probably exceeds the importance of this innovation. From this chaotic volume, numerous materials and various techniques have been, and continue to be, promulgated but few factual conclusions can be drawn. There are, as yet, no reliable statistics as to the frequency with which such substances are currently being employed and no definite figures as to the complications or the recurrences which follow in their train. These deficiencies render informed indications difficult to establish. Of the many materials that have been advocated, autogenous fascia lata would appear to possess the most desirable qualities. The woven plastic meshes seem to be favored among the artificial devices. All of these are associated with complications in greater frequency and variety than are encountered with the traditional suture methods of operation. Furthermore, they have not furnished the ultimate solution for the hernia problem. While the incidence of recurrences is as yet unknown, failures have been reported with all of these surgical adjuvants and it now appears that all tend to fracture or weaken with the passage of time. Prostheses, whatever their value, cannot replace a full knowledge of the underlying anatomy and pathology of hernia, or substitute for the exercise of the time-honored principles of surgical technique. They are apparently being used more frequently and with less selectivity than the nature of the lesion demands. In my own opinion, such surgical aids are virtually never required in primary inguinal or femoral hernias. Following multiple recurrences, they may occasionally be indicated. Their real sphere of usefulness is in the mammoth-sized postoperative ventral hernia which otherwise might not be at all operable. Prostheses have not proved to be the ultimate solution to the hernia problem and only time will tell when and how often they should be used and what may be expected therefrom.
REFERENCES 1. Adler, R. H.: An evaluation of surgical mesh in the repair of hernias and tissue defects. Arch. Surg., 85:836-844, 1962. 2. Brandon, W. j. M.: Inguinal hernia. The unpredictable result. Brit. J. Surg., 34:14-18, 1946. 3. Guy, C. C.: Discussion of paper by R. S. Smith. 4. Guy, C. C., Werelius, C. Y., and Bell, L. B.: Five years' experience with tantalum mesh in hernia repair. SURG. CLIN. N. AMER., 35:175-188, 1955. 5. Johnson, C. G.: Discussion of paper by R. S. Smith. 6. Koontz, A. R.: Hernia. New York, Appleton-Century-Crofts, 1963. 7. Maier, R. L.: Use and abuse of inert materials in hernia repairs (Editorial). Amer. J, Surg., 94:1, 1957.
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8. McVay, C.: Discussion of paper by R. S. Smith. 9. Smith, R. S.: !\djuncts in hernial repair. Arch. Surg., 78:868-875, 1959. 10. Smith, R. S.: Use of _;;tdjuncts in hernia repair: Basic principles. In Hernia (L. M. Nyhus and H. N. Harkins, Eds.). Philadelphia, J. B. Uppincott Co., 1964. 11. Taylor, F. W., and Jontz, J. G.: Incisional hernia repair. Surgery, 48:528-533, 1960. 12. Usher, F. C.: Hernia repair with Marlex mesh. In Hernia (L. M. Nyhus and H. N. Harkins, Eds.). Philadelphia, J. B. Uppincott Co., 1964. 13. Zimmerman, L. M.: Recent advances in surgery of inguinal hernia. SuRG. CLIN. N. AMER., 32:135-153, 1952. 14. Zimmerman, L. M., and Anson, B. J.: Anatomy and Surgery of Hernia. Baltimore, Williams & Wilkins Co., 1953. Second edition in press. 55 East Washington Street Chicago, Illinois 60602