During the past decade, remarkable progress has been made in herniology, which has emerged as a subspecialty of general surgery with its own societies, journal, and clinics. Consequently, care of the most common hernia, that of the groin, has improved vastly. In this monograph, recent advances in our knowledge of this defect and the techniques that are available for its repair are documented in relation to our previous understanding.
Classically, the cause of inguinal hernia, whose incidence is highest in infancy and old age, has been attributed to congenital factors. In infants, preterm birth and persistence of the processus vaginalis have been blamed. Innate anatomic variations in the architecture of the groin have been held responsible in the adult. Although atrophy of the internal oblique muscle and “conjoint tendon” has long been recognized, surgical anatomists (with notable exceptions, who were ignored) have assumed that the tissues themselves were normal and would stay so.
This doctrine was challenged in the 1960s and 1970s. Evidence accrued that systemic damage to collagen could develop in adults and lead to groin herniation and its recurrence after pure tissue repairs. The first observations were made in patients with lathyrism who were noted to have an unexpectedly high incidence of rupture. When a lathyrogen (beta-aminopropionitrile) that was known to inhibit the hydroxylation of proline and therefore the cross-linkage of collagen fibrils selectively was administered to animals, groin hernias appeared. Soon after that report, attenuation of the rectus sheath was described among patients who had undergone operation for inguinal herniation. Microscopically, pathologic changes in collagen, different from those elicited by lathyrism, were observed. Later, similar changes were reported on the uninvolved side, in skin, and in pericardium. Thus, a systemic defect in collagen had been demonstrated in men in late middle age with primary inguinal hernias.
Fibroblast cultures revealed reduced synthesis of an abnormal collagen. Blood protease-antiprotease studies demonstrated an imbalance that favored proteolysis. The term metastatic emphysema suggested that these patients who (almost all) had taken advantage of free cigarettes sent up with the rations were now “paying for” them. They experienced a spillover into the peripheral circulation of metabolic products that derived from inhaled smoke. Activated leukocytes with their proteases that were concentrated in the lungs were also migrating through the blood stream. Therefore, smoking was not only causing emphysema and septic bronchitis in the thorax but also indirectly affecting the rest of the body.
During the 1980s, many of these observations were confirmed and extended. A parallel was drawn with the cardiovascular effects of smoking. Similar connective tissue damage to that encountered in patients with groin herniation was identified in cases of abdominal aortic and cerebral aneurysms. This finding persisted after aneurysm excision and was associated with an increased incidence of groin herniation.
In the last decade, molecular biochemical techniques have revealed that abnormal collagen synthesis in patients with groin herniation is caused by an alteration in genetic expression. The predominant type I collagen is reduced, with an increase in the next most common type, type III. This change in the normal ratio reduces the strength and binding capacity of the collagen fibers, and a weaker product results. It is not yet clear at what point in the transition, within the cell, between genotype and phenotype, the injury occurs. Elastic tissue and muscles are also affected. The shutter effect at the internal inguinal ring is thereby diminished. Indirect and direct defects are encountered; the damage to the transversalis fascia is greater in the direct defects. Increased rates of recurrence after inguinal herniorrhaphy, which are observed in both men and women who smoke, can be explained by a failure of their fibroblasts to form a mature scar after operation. Reduced and abnormal collagen synthesis combines with enhanced proteolysis. Interestingly, the abnormal collagen synthesis “normally” increases in elderly patients.
Not everyone who in adult life experiences inguinal herniation smokes. A familial tendency has been well known, and various heritable connective tissue disorders are associated with inguinal defects. Polycystic disease of the kidney has been added to the list recently. Transmission appears to be autosomal dominant, with incomplete penetrance of a preferential paternal factor. Most of these conditions arise from genetic mutation. An association between those with joint hypermobility and inguinal hernia has been described recently. In these cases, fibroblasts secreted twice the normal amounts of type III collagen, and patients had a decreased number of thick (polymeric) fibrils. Thus, damaged collagen, in association with groin herniation, has a multifactorial cause.
Evidence regarding abnormal mesodermal tissue, along with continuing concern regarding unrelieved tension in pure tissue repairs, has accelerated acceptance of tension-free prosthetic herniorrhaphy. Several techniques are available that approach the defect from above or below, preperitoneally or subaponeurotically, with open or laparoscopic surgical procedures. At least 2 “right” ways have resulted. The first is preperitoneal closure of Fruchaud's orifice with an overlapping prosthesis, inserted either anteriorly or posteriorly. This approach has been popularized with the use of Mersilene mesh. This technique has been adopted by laparoscopists who use polypropylene, including parietalization instead of keyholing, thereby preserving the strength of the prosthesis.
Another “right” way is reinforcement of the intermediate (muscular) inguinal ring and, laterally, the internal oblique musculature with a tightened keyholed prosthetic mesh, which is placed subaponeurotically. The medial direct area of transversalis fascia is also covered. This (the Lichtenstein procedure performed open) is now the gold standard worldwide. Polypropylene mesh is used. Proponents of prosthetic plug repair, with the use of the same plastic, usually combine preperitoneal placement with a keyholed mesh that is placed subaponeurotically. A prospective randomized study has shown both “right” ways are equally effective. The Lichtenstein repair is easier to perform than preperitoneal prosthetic coverage. The plug technique combines 2 “right” ways. There is the question, yet to be answered, of whether both “belt and braces” are necessary.
Recurrence rates have fallen so low that other parameters have received attention in conjunction with quality of care. These parameters include pain, rehabilitation (including return to work), cost, and patient satisfaction. Epidemiologic studies have been undertaken to determine how well large populations are being treated. Randomized prospective studies that compare different repairs are being conducted so that the patient and the local doctor do not have to rely on the word of experts or commercial vendors. This evidence-based herniologic experience has stimulated attempts to obtain a consensus on classification and an insistence on the standardization of the particular procedure under examination. Much of this work has been pioneered in Europe.
Tension-less prosthetic repair of primary and recurrent groin herniation in the adult gives rise to fewer failures than the best of the pure tissue procedures, the Shouldice (modern Bassini) repair. Furthermore, the former procedures are easier to perform, take less time, require little training, and provide a smoother recovery. Open and laparoscopic placement of the mesh (usually polypropylene) gave equivalent results. However, the laparoscopic placement technique was not used as much, especially in elderly patients, because of the need for general anesthesia, carbon dioxide insufflation, and special training. Increased cost was another negative factor, but efforts are being made to reduce the cost. To avoid further damage to scarred elements of the spermatic cord and the inguinal nerves, laparoscopy is being used more in recurrent hernias and for patients with bilateral defects.
Excision of the cremasteric apparatus, muscle, genital branch of the genitofemoral nerve, and the external spermatic vasculature, a mainstay of the Shouldice tissue repair is not required with prosthetic procedures. The Lichtenstein or plug procedures do not depend on the internal inguinal ring being dissected out and uncovered. Laparoscopic posterior prosthetic placement is at the neck of the processus vaginalis within the supernumerary internal ring and in the posterior lamina of transversalis fascia deep in the iliac fossa. Testicular drop or atrophy are obviated. Lipomatous herniation of extraperitoneal fat, which is more difficult to treat laparoscopically than from below, must be distinguished after excision from the rare giant lipoma or sarcoma.
Absorbable meshes have no place in groin herniorrhaphy. It was hoped that their combination with permanent prostheses in composites would prevent visceral erosion, but they are removed too rapidly by the body. Their content, however, is being added to polypropylene mesh during manufacture so that unnecessary bulk can be eliminated, larger pore size can be obtained, and the prosthesis in the asthenic and elderly patient will not be palpable or painful.
Despite the widespread use of mesh, infection is now no more frequent than in tissue repairs. Because of these results, prophylactic antibiotics are no longer recommended routinely in the absence of evidence regarding their efficacy. They are, however, still administered intravenously at operation in selected cases (ie, cardiac and orthopedic prosthesis, mitral valve prolapse, diabetes mellitus, and certain elderly patients). The emphasis is on prevention. Careful antiseptic preparation of the skin, absence of associated inflammation, limited cauterization, good surgical technique, and the use of monofilament sutures are required. The mesh is inserted with some slack and must be smoothed out to avoid wrinkles.
Epidemiologic data now show that, despite intense legal, insurance, and compensation interest, most patients with new onset groin herniation have no recollection of any episode of heavy lifting. Most hernias are painless initially. When a patient has pubalgia with no obvious protrusion (a recently described entity), adductor tenoperiostitis must be ruled out. This is surprisingly common in men who partake in sport, especially elderly patients. Herniography or magnetic resonance imaging studies may be needed in the evaluation. Ultrasonography is more useful with femoral protrusions. Rare or multiple herniation can be revealed (and treated) by laparoscopy. In children, enlargement of the external inguinal ring is all but diagnostic of a hernia. Unexpected findings at herniotomy include peritoneal implants of tuberculosis or metastatic (colon) cancer.
The popularity of ambulatory surgery has enhanced the role of local anesthesia. Epidural anesthesia has become an alternative. In elderly patients, quicker recovery and a decreased risk of urinary retention, aspiration, and delirium have all influenced the switch from general anesthesia. Preterm infants pose problems for the anesthesiologist because of the small tracheal size and immature respiratory function. Postoperative apnea is a particular concern. Young children still receive general anesthesia. Improved laryngeal airways and short-acting agents have improved anesthetic treatment. In the adult, most emergency repairs are conducted with the use of general anesthesia because viscera may require resection.
Only 2% to 4% of groin hernias are femoral. However, they are more common in women (62%). These protrusions are often incarcerated (40%) and, especially in elderly patients, may be strangulated. The hernias therefore must be repaired as soon as possible. Laparoscopy has revealed several rare variants (ie, prevascular, retropsoas) recently. Open plug repair from below is popular. If an emergency operation is required to relieve strangulation of any groin hernia (usually inguinal in men [5%]), recent studies have shown that prosthetic repair can be added safely, despite visceral resection. Every effort should be made to perform the surgical procedure within 4 hours of onset. Intravenous antibiotics are continued for 2 to 5 days. After the intraperitoneal part of the procedure is concluded, fresh sterile equipment is obtained, and a preperitoneal Stoppa prosthetic placement is completed. Antiseptic packs are used to wall off infected areas before closure.
Postoperative pain, which previously was underappreciated, has received a lot of attention recently. Continuing pain suggests other causes (such as tendonitis or lumbosacral disease, which are diagnoses that should have been identified before operation). New severe onset pain in the recovery room is rare and indicates intraoperative nerve injury. If this is defined neurologically and eliminated by selective nerve block, early reoperation is advisable. Wound exploration usually reveals the cause. If the exact point of injury cannot be determined before operation, proximal neurectomy of 1 or more inguinal nerves can be remedial, which may be accomplished best laparoscopically.
Pubalgia, late in onset, may again result from associated morbidity, but a new syndrome, mesh inguinodynia, has been described recently. This condition is caused by an inflammatory response to the prosthesis, which then extends to the inguinal nerves. It can be disabling but, fortunately, is uncommon. If analgesics and anti-inflammatory agents fail to relieve the symptoms, excision of the mesh with proximal neurectomy may be required (75%). Surprisingly, because of intercommunication between the various inguinal nerves, this procedure results in little or no anesthesia.
Considering the proximity of the groin to the genitalia, it is not surprising that sexual dysfunction may follow herniorrhaphy. Psychogenic impotence is generally temporary. Its possibility emphasizes the need to take a sexual history before operation, with reassurance later. Dysejaculation, another new syndrome, affects 0.04% of patients. This condition may be delayed or immediate. It relates to scarring of the vas deferens and, in some cases, is attributed to mesh inguinodynia. Again, most patients recover with time. Atrophy of the testis (0.35%) is increased after surgical procedures for recurrences (0.5%). Its incidence has decreased because scrotal dissection has been avoided, except in cases of irreducible incarceration. A reduced sperm count and infertility can result from the development of antibodies. Transection of the vas deferens is rare and necessitates reanastomosis, such as after surgical procedures for contraception.
The modern approach to groin herniorrhaphy in children differs little from the approach used in the 19th century. High ligation of the processus vaginalis or canal of Nuck is the mainstay. Laparoscopic repair (without prostheses) has not gained acceptance, but this technique is being used increasingly intraoperatively to exclude a contralateral protrusion. Incarceration is common in infants (30%); therefore, early operation is indicated because this complication can compromise the blood supply of the testicle. The fallopian tube may be encountered as a sliding hernia in 20% of female infants. This fact mandates an inspection of the protrusion before ligation.
Elderly patients are becoming more numerous, and more than one half of all groin hernioplasties now are performed in those who are older than 50 years. Atrophic changes exacerbate metabolic damage to collagen. Comorbidities of elderly patients have influenced the type of anesthesia used for surgical procedures. Local anesthesia is being used more and more to avoid the urinary and respiratory complications, as well as delirium in the recovery room, which are encountered with general anesthetics. More femoral hernias are encountered in women, and these are often incarcerated. Some caregivers have suggested that asymptomatic direct herniation in elderly patients is best left alone. Nevertheless, most surgeons continue to operate because these defects tend to enlarge and interfere with quality of life. In addition, the results of repair have been surprisingly good. Prospective studies are underway.
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