Hernia Surgery (Hernia Repair)

Executive Summary

Hernia repair is one of the most frequently performed operations in the world; for groin hernia alone, more than 20 million repairs are carried out each year [7,20]. More than four decades of accumulated randomised evidence converge on a handful of robust principles.

The first is that, in symptomatic hernias, mesh reinforcement is superior to pure tissue (suture) repair and durably lowers recurrence. This superiority was first demonstrated in incisional hernia by Luijendijk et al. (2000) and confirmed at 10-year follow-up by Burger et al. (2004): cumulative recurrence was 63% with suture versus 32% with mesh (P < 0.001); even in small hernias, 67% versus 17% (P = 0.003) [2,10].

The second is that watchful waiting is safe over the short to medium term in men with asymptomatic or minimally symptomatic groin hernia — although most patients ultimately cross over to surgery [5,6]. The third is that minimally invasive repair in experienced hands reduces early pain and wound morbidity compared with open repair; here the true determinant of recurrence is the learning curve [7,12]. The fourth concerns the robotic platform: despite its rapid uptake, level-I studies have not demonstrated a clear patient-level benefit over laparoscopy in standard ventral or groin repair, while it has increased operative time and cost [16,17].

From a clinical standpoint, the paradigm has shifted from a recurrence-centred model to a patient-centred one. Today chronic postoperative inguinal pain (CPIP) — affecting roughly 6–18% of patients depending on approach and definition — rivals recurrence as the primary concern [18,24]. There is no single "best operation"; technique selection is now governed by individualisation: defect size, contamination, sex, previous repairs, connective tissue status and surgeon volume.

Current best practice is a patient-tailored, mesh-based tension-free repair performed by a high-volume surgeon. In patients who prioritise rapid recovery, and in bilateral groin hernias and those recurring after a previous anterior approach, the laparoscopic/endoscopic approach comes to the fore. In complex midline reconstruction, posterior component separation with transversus abdominis release (TAR), retromuscular/sublay rather than intraperitoneal mesh placement wherever feasible, and ERAS pathways with prehabilitation in major abdominal wall reconstruction are preferred.

Looking ahead, the growth areas are clear: artificial-intelligence-assisted preoperative risk stratification and intraoperative guidance; next-generation lightweight, bioabsorbable and hybrid meshes; tissue-engineered and regenerative scaffolds aimed at biological integration; robotic eTEP and rTARM techniques; and national hernia registries generating ever more real-world comparative effectiveness data (Abdominal Core Health Quality Collaborative, Swedish Hernia Register, EuraHS).

Historical Evolution of Hernia Surgery

The history of the field can be summarised in three major transitions. The first is the move from tension-bearing tissue repair to tension-free mesh repair (Usher → Lichtenstein). The second is the shift from an anterior to a posterior/preperitoneal approach (Stoppa → TEP/TAPP). The third, which matured in the 2010s, is the turn from a recurrence-focused to a patient-reported outcome-focused perspective (pain, quality of life). Robotic surgery is not a fourth revolution replacing any of these three; it is better positioned as a tool that facilitates the technically demanding parts of the second transition.

Epidemiology and Disease Burden

Abdominal wall hernias are among the highest-volume categories of both elective and emergency general surgery worldwide. Groin hernias (inguinal + femoral) are the dominant group and account for roughly three quarters of all abdominal wall hernias [19].

The figures make this scale concrete. More than 20 million groin hernia repairs are performed worldwide each year [7,20]; in the United States alone this amounts to approximately 700,000 herniorrhaphies annually [13]. The lifetime risk of developing a groin hernia is about 27% in men and about 3% in women — roughly a ninefold male predominance [15]. In children, groin hernias are almost exclusively of the lateral (indirect) type, whereas in adults both lateral and medial (direct) subtypes are seen [15].

Incisional hernia, by contrast, is a burden generated by surgery itself. Incisional hernia develops in 10–15% of patients undergoing midline laparotomy [20]; this staggering rate forms the fundamental rationale for prophylactic mesh placement at the index laparotomy (see Section 31).

The economic dimension is also far from negligible: in Europe alone, the annual cost of hernia repair is estimated to exceed €3 billion. This burden has two modern faces — recurrence, historically the dominant metric, and chronic postoperative inguinal pain (CPIP), which today drives much of the loss of quality of life, disability and reoperation.

The scale is so large that even small proportional improvements in recurrence or chronic pain translate into enormous absolute population benefit. This is precisely the central rationale for standardisation, surgical subspecialisation and registry-based quality improvement.

The strength of evidence for volume and lifetime risk estimates is high (consistent across multiple registries and reviews). Some points, however, remain contested. Foremost among them is whether obesity is a genuine risk factor: several epidemiological studies suggest that groin hernia prevalence is paradoxically lower at high BMI. This finding is more likely attributable to hernias being missed in a thick abdominal wall — that is, to diagnostic difficulty — than to any protective effect [19]. By contrast, there is no dispute that obesity increases the risk of incisional hernia and wound complications. As for knowledge gaps, reliable incidence data from low- and middle-income countries are scarce; there is marked under-reporting and reduced surgical access.

Anatomy

Competent hernia surgery is, in essence, applied anatomy; every choice of approach maps directly onto the layers of the abdominal wall.

The inguinal canal is approximately 4 cm long. It runs from the deep (internal) inguinal ring — a defect in the transversalis fascia lateral to the inferior epigastric vessels — to the superficial (external) ring, the opening in the external oblique aponeurosis. It transmits the spermatic cord in men and the round ligament in women. The canal is bounded anteriorly by the external oblique aponeurosis, posteriorly by the transversalis fascia and conjoint tendon, inferiorly by the inguinal ligament, and superiorly by the internal oblique and transversus abdominis muscles.

Modern preperitoneal repairs (laparoscopic/robotic and open Stoppa) are built around a single concept: the myopectineal orifice of Fruchaud (MPO). This opening, the sole area of weakness in the groin, is bounded as follows:

• Superiorly: the internal oblique / transversus abdominis arch
• Medially: the rectus muscle
• Laterally: the iliopsoas muscle
• Inferiorly: Cooper's (pectineal) ligament

The inguinal ligament divides this area into inguinal and femoral compartments. Since all groin hernias emerge from the MPO, the fundamental logic of posterior/preperitoneal repair follows directly: covering the entire MPO with mesh closes not only the existing hole but every hole that might open in the future.

Several structures in this region are of vital importance. The inferior epigastric vessels are the anatomical landmark distinguishing a direct (medial) hernia from an indirect (lateral) one. Bounded medially by the vas deferens and laterally by the gonadal vessels lies the "Triangle of Doom", which contains the external iliac vessels — no tack or staple is ever placed here. The "Triangle of Pain", lateral to the gonadal vessels and below the iliopubic tract, contains the lateral femoral cutaneous nerve and the femoral branch of the genitofemoral nerve; fixation in this zone causes neuralgia. In open repair, the ilioinguinal, iliohypogastric nerves and the genital branch of the genitofemoral nerve are at risk — these three nerves constitute the anatomical basis of CPIP.

Turning to the midline, the picture is as follows: the rectus abdominis muscle lies within the rectus sheath, and the midline raphe is formed by the linea alba. The lateral abdominal wall comprises three muscles — external oblique, internal oblique and transversus abdominis; their aponeuroses form the rectus sheath. In complex reconstruction, the retrorectus (Rives–Stoppa) plane and transversus abdominis release (TAR) open wide, well-vascularised planes for sublay mesh.

Ultimately, the choice of approach follows the map of these planes: open anterior repair reaches the canal from the front; laparoscopic TEP/TAPP and open Stoppa enter the MPO from behind; and TAR extends the retromuscular plane laterally for very large defects.

Pathophysiology

Hernia formation arises from the interaction of three factors: a structural defect, mechanical load (raised intra-abdominal pressure) and tissue quality (connective tissue / collagen homeostasis).

The weighting of these factors varies by subtype. Lateral (indirect) inguinal hernias are strongly associated with a patent processus vaginalis, as well as with failure of the physiological "shutter" and "sphincter" mechanisms of the internal ring; cumulative mechanical exposure is added to this [15]. Medial (direct) hernias, by contrast, are more consistently accompanied by profoundly altered connective tissue architecture — pointing to collagen metabolism rather than to a purely congenital mechanism [15].

Contributing factors include chronic cough, constipation with straining, heavy lifting, ascites, pregnancy, prostatism, obesity (contested), smoking and advanced age. Incisional hernias, in turn, result from failure of fascial healing after a previous laparotomy; here the dominant factors are wound infection, obesity and poor surgical closure technique.

The relative weight of "plumbing" (mechanical) versus "pipe material" (biological) causation differs by subtype; the two pathways are, however, not mutually exclusive [15]. At this point the field's most fundamental unresolved question emerges: it still cannot be explained why only a proportion of patients with a patent processus vaginalis develop a hernia. This gap is regarded as the strongest indirect evidence for the tissue quality hypothesis.

Structural

• Patent processus vaginalis
• Previous laparotomy / fascial failure
• Weak myopectineal orifice

Raised Intra-abdominal Pressure

• Chronic cough / COPD
• Constipation / straining
• Heavy lifting
• Ascites, pregnancy, prostatism

Tissue Quality

• Altered collagen I:III ratio
• Connective tissue disorders
• Smoking
• Advanced age

Risk Factors

For the development of groin hernia

• Male sex (≈9× risk)
• Advanced age
• Family history of hernia (heritable component)
• Patent processus vaginalis
• Chronic cough / COPD
• Chronic constipation and straining
• Prostatism / obstructive urinary symptoms
• Heavy physical work / heavy lifting
• Smoking (impairs collagen metabolism)
• Connective tissue disorders (Ehlers–Danlos, Marfan)
• Ascites, peritoneal dialysis
• Low body mass index (the paradoxical association of obesity — see Section 3)

For the development of incisional hernia

• Midline laparotomy (particularly emergency)
• Surgical site infection (the strongest modifiable factor)
• Obesity
• Poor fascial closure technique (inadequate suture-to-wound length ratio)
• Smoking
• Diabetes / poor glycaemic control
• Malnutrition
• Steroid / immunosuppressant use
• Chemotherapy
• Aortic aneurysm (a marker of connective tissue disorder)

For recurrence

• Previous repair(s)
• Pure tissue (non-mesh) repair
• Low surgeon volume / early phase of the learning curve
• Continued smoking
• Obesity
• Large defect width (W3, ≥10 cm)
• Contamination / infection
• Inadequate mesh overlap or bridging technique

Genetics and Collagen Biology

Impaired connective tissue quality is increasingly recognised as a systemic and heritable substrate for both primary and recurrent hernia.

The most concrete indicator of this is collagen composition. The type I : type III collagen ratio is reduced in patients with inguinal, incisional and recurrent hernia. Because type I collagen provides greater tensile strength, a relative shift towards the thinner, more elastic type III weakens fascial integrity [15].

Serum biomarker studies likewise reveal systemically altered collagen turnover in hernia patients: in groin hernia, type III/V turnover is reduced while basement membrane (type IV) turnover is increased. The critical point is this — these abnormalities persist after repair (Lorentzen et al., 2018) [9]. In other words, we are dealing with an underlying genetic or acquired synthesis defect; a hernia is not "a punctured tyre" but "a fatigued material".

On the genetic front, groin hernia has a hereditary component with complex inheritance; genome-wide studies have identified susceptibility loci overlapping with genes involved in connective tissue homeostasis [15]. Syndromic connective tissue disorders such as Ehlers–Danlos and Marfan also markedly raise hernia risk.

The practical significance of this section lies in the persistence of the collagen abnormality after repair; this single finding provides biological justification for two things. First, mesh reinforcement even in "small" defects — because the real problem is not the size of the hole but the quality of the material. Second, heightened vigilance for recurrence in patients with connective tissue disease.

The strength of evidence in this area is moderate (consistent biomarker and case-control signals exist, but are limited by small samples and wide biomarker ranges). Whether the change in collagen ratio is cause or consequence remains unclear. Looking forward, genetic profiling and serum collagen-turnover panels that would enable personalised prehabilitation and mesh selection are the most promising research avenues.

Classification Systems

A standard classification makes comparable outcome reporting and the tailoring of technique to defect possible.

8.1 Groin hernia — EHS classification

This is a grid system:

• Type: L (lateral/indirect), M (medial/direct), F (femoral)
• Size: 0–3 (defect measured in fingerbreadths; 1 = ≤1.5 cm, 2 = 1.5–3 cm, 3 = >3 cm)

In research reporting, this system has replaced the older eponymous systems (Nyhus, Gilbert).

8.2 Ventral / incisional hernia — EHS classification (Muysoms et al., 2009)

Primary hernias: by location (midline: epigastric, umbilical; lateral: Spigelian, lumbar) and by diameter.

Incisional hernias: by midline (M1–M5) or lateral (L1–L4) zone, by width and by recurrence status:

• W1: <4 cm
• W2: 4–10 cm
• W3: ≥10 cm

Width is the single most decisive variable in technique selection: W1 defects can be handled with a simple sublay repair, whereas W3 defects require component separation ± TAR.

8.3 Contamination

The CDC surgical wound classification (clean → clean-contaminated → contaminated → dirty) critically determines mesh selection and antibiotic decisions.

Clinical Presentation

The typical patient presents with a reducible groin or abdominal wall swelling that becomes prominent on standing, coughing or straining; this is often accompanied by a dragging/heavy sensation or dull discomfort.

Not every hernia, however, is vocal. Up to one third of groin hernias are asymptomatic or minimally symptomatic [5,15]; this is the clinical basis of the watchful waiting debate.

Emergency and red-flag presentations demand separate attention:

In a clinically obvious hernia, history and physical examination remain the cornerstone of diagnosis. Imaging is better reserved for diagnostic uncertainty, occult hernia or assessment of recurrence (see Section 10).

Diagnostic Imaging

Imaging does not replace clinical examination; it complements it.

When complex abdominal wall reconstruction is being planned, what guides decisions are CT-based measurements: defect width (W1/W2/W3 classification), the presence and degree of rectus diastasis, and the ratio of hernia sac volume to peritoneal volume — the last of which defines the concept of loss of domain. These three measurements directly determine decisions on preoperative botulinum toxin A, progressive pneumoperitoneum and component separation.

The strength of evidence for imaging is moderate; it increases diagnostic accuracy in equivocal cases but adds cost and risks overtreatment of occult findings. Indeed, the management of incidentally detected contralateral or occult hernias — particularly whether an asymptomatic contralateral hernia seen during laparoscopic TAPP should be repaired in the same session — remains a contested question.

Natural History

Understanding the course of an untreated hernia establishes the basis for the shared decision of "operate or observe".

The landmark in this area is the study by Fitzgibbons et al. (2006) published in JAMA. Randomising minimally symptomatic men to watchful waiting or repair, this study showed that the rate of acute "hernia accidents" (incarceration/strangulation) is very low — approximately 1.8 events per 1,000 patient-years [5]. In short, watchful waiting is safe in the short term.

Symptoms do, however, progress over time. Long-term follow-up has shown that most men eventually cross over to surgery [6]. In the INCA trial (van den Heuvel et al., 2023, eClinicalMedicine), men aged 50 years and over were followed for 12 years; roughly a quarter never required surgery, and at the end of follow-up approximately 50% still had not crossed over [21]. A meaningful minority can therefore safely postpone surgery indefinitely.

In conclusion, watchful waiting does not prevent surgery for most patients — it defers it — but it is safe. The low rate of acute complications legitimises observation in truly asymptomatic men who understand the likelihood of crossover. The strength of evidence on this question is high (multiple mutually corroborating RCTs with long follow-up).

Conservative Management

Non-surgical strategies fall under two headings: structured watchful waiting and the use of a truss.

Watchful waiting is an evidence-based, acceptable option for asymptomatic or minimally symptomatic men [5,6,7]. An individual participant data meta-analysis of long-term RCTs supports this: while a high crossover rate to surgery over time was confirmed, short-term safety was corroborated (Yeow et al., 2024) [22].

A truss, by contrast, provides symptomatic support but does not treat. Because it can lead to complications such as skin breakdown, testicular atrophy and worsening of the defect, it should be reserved solely for patients who are unfit for or who decline surgery.

Unanswered questions remain in this area: the optimal surveillance intervals and the predictors of the minority who will never require surgery are as yet unknown.

Indications for Surgery

Repair is indicated to relieve symptoms and to prevent — or to treat — incarceration/strangulation.

The position of the HerniaSurge (2018) guideline is clear [7]: surgery is recommended for symptomatic groin hernias; watchful waiting may be accepted as an option in asymptomatic or minimally symptomatic men; prompt repair is recommended in women because of the risk of occult femoral hernia; repair is recommended for all femoral hernias; and emergency presentations require emergency surgery.

In ventral/incisional hernia the indication is more a matter of balance: symptoms, enlargement of the defect, obstructive episodes, cosmetic concerns and breakdown of skin integrity on one side; operative risk on the other. Particularly in obese and comorbid patients, prehabilitation — weight loss, smoking cessation, glycaemic optimisation — improves outcomes and should be implemented before elective repair (see Section 21).

The strength of evidence is high for the recommendations on symptomatic repair and femoral hernia, and moderate for optimal timing in comorbid ventral hernia.

Open Surgical Techniques

Open repair remains the backbone of the global workload — the Lichtenstein tension-free mesh repair above all.

14.1 Techniques

Lichtenstein (open anterior mesh repair). A flat mesh that reinforces the posterior wall, and the reference standard for open repair: reproducible, low recurrence, easy to teach. It can be performed under local, regional or general anaesthesia — a significant advantage over laparoscopy, which requires general anaesthesia.

Shouldice (tissue repair). A multilayered pure tissue repair. It is the mesh-free option with the lowest recurrence among tissue repairs, but it is technically demanding and the learning curve is steep. Its use today is confined to mesh refusal or a contaminated field.

Plug-and-patch / bilayer devices. These are alternatives with comparable recurrence rates and, in some data, shorter operative times; concerns nevertheless persist regarding plug-related complications (migration, erosion, meshoma).

Open preperitoneal (Stoppa / TREPP / Kugel). Covers the MPO posteriorly through an open approach; useful in recurrent or bilateral disease.

14.2 Current evidence — mesh vs suture

A Cochrane review (Lockhart et al., 2018) showed that mesh repair reduces recurrence compared with non-mesh repair in inguinal/femoral hernia [8]. For incisional hernia, the strongest evidence comes from the Luijendijk (2000) → Burger (2004) line, with 10-year follow-up [2,10]:

The most striking row of this table is the second: the intuition that "small hernias do not need mesh" has been clearly refuted by the evidence. In small defects the relative benefit of mesh is even greater than in large ones. The biological explanation is in Section 7: the problem is not the diameter of the hole but the quality of the tissue.

Pooled meta-analyses point consistently in the same direction: synthetic mesh reduces recurrence by 50–75% compared with pure tissue suture repair across virtually all abdominal hernia types.

In short, open Lichtenstein remains an excellent and cost-effective default, particularly where laparoscopic expertise and equipment are limited. Points still debated in the field remain: whether heavyweight or lightweight mesh should be used; and whether mesh can be omitted in very small (<1–2 cm) ventral defects — recent propensity-score matched data suggest comparable recurrence may be achievable with non-mesh repair as well (Nguyen et al., 2024, Surgery). The strength of evidence for the benefit of mesh, however, is high.

Laparoscopic Surgery (TEP and TAPP)

There are two dominant endoscopic techniques — TEP (totally extraperitoneal) and TAPP (transabdominal preperitoneal). Both cover the MPO by placing the mesh in the preperitoneal space. For ventral defects, IPOM (intraperitoneal onlay mesh) is used.

15.1 TEP vs TAPP

In terms of recurrence and chronic pain the two techniques are broadly equivalent [7,8].

In practice: TAPP is more forgiving and diagnostically richer; TEP is theoretically "cleaner" because it never enters the peritoneal cavity, but it is technically more demanding.

15.2 Laparoscopic vs open — the VA trial and the learning curve

The VA trial by Neumayer et al. (2004), published in the NEJM (CSP 456; N = 2,164 randomised), produced results that at first glance appear to disfavour laparoscopy [12]. Two-year recurrence was 10.1% in the laparoscopic group and 4.9% in the open group — that is, laparoscopic repair fared worse; moreover, more life-threatening complications occurred in the laparoscopic group.

But the trial's most critical nuance enters here: the results were heavily influenced by surgeon inexperience. The recurrence rate fell sharply once a surgeon's experience exceeded roughly 250 cases. Indeed, in subsequent meta-analyses the difference in recurrence loses significance when the Neumayer trial is removed from the analysis. The conclusion reached by the guidelines is clear: with adequate experience there is no significant difference in recurrence; in return, laparoscopic repair delivers less early and chronic pain and faster recovery [7].

15.3 Mesh fixation

For TAPP, meta-analyses show that omitting fixation does not increase recurrence: RR 0.83 (95% CI 0.29–2.39; P = 0.73); it may moreover reduce acute pain — although the certainty of evidence is low (Zhang et al., 2024) [23]. When fixation is required, the golden rule is unchanged: tacks are never placed in the "Triangle of Doom" or the "Triangle of Pain" (see Section 4).

In summary, laparoscopic repair is guideline-preferred in bilateral groin hernias and in those recurring after open repair, as well as in patients who prioritise a rapid return to activity — provided surgeon volume is adequate. The strength of evidence is high for the recovery benefit and moderate (and experience-dependent) for recurrence equivalence.

Sources: Neumayer et al. (2004); Lockhart et al. (2018); HerniaSurge (2018); Reinpold (2017); Simons et al. (2009).

Robotic Hernia Surgery

Robotic platforms offer wristed instrumentation, 3D vision and ergonomic advantages. These features particularly facilitate intracorporeal suturing — in tasks such as fascial closure, defect approximation, mesh fixation and complex reconstruction.

16.1 Level-I evidence: two randomised trials, the same conclusion

The RIVAL trial (Prabhu et al., 2020, JAMA Surgery) — robotic vs laparoscopic TAPP in groin hernia [17]:

No measurable clinical benefit for the robotic approach; in return, longer operative time, higher cost and greater surgeon fatigue/frustration.

The PROVE-IT trial (Petro et al., 2021, JAMA Surgery; N = 75) — robotic vs laparoscopic IPOM in ventral hernia [16]:

No significant difference in postoperative pain (POD1, NRS-11), complications, quality of life or length of stay. Robotic operations took markedly longer: median 146 min vs 94 min (P < 0.001) and were more expensive. The authors' conclusion: "no discernible clinical benefit".

16.2 Counter-evidence

There is also a signal to the contrary. A multicentre ventral RCT (Dhanani/Liang et al., 2021, Annals of Surgery; 2-year outcomes 2023) [3] reported that robotic repair delivered at least similar and possibly improved outcomes at 2 years — pointing to a potential benefit, but together with a call for more multicentre data.

16.3 Meta-analytic synthesis

Pooled RCTs and propensity-score matched analyses generally paint the following picture:

• Longer operative time and higher cost with robotics (including docking time)
• Comparable recurrence
• Comparable clinical safety (RR ≈ 1.1 for complications)
• A possible reduction in some wound morbidity, or easier fascial closure
• But no consistent and definite patient-level advantage over laparoscopy in standard cases

16.4 Where does the robot's real value lie?

The robot's clearest value lies not in small, routine hernias but in complex reconstruction:

• Robotic eTEP (extended totally extraperitoneal)
• rTARM (robotic transabdominal retromuscular)
• Robotic TAR (transversus abdominis release)

In these techniques, advanced suturing capability lowers the technical barrier to minimally invasive posterior repairs. In other words, the robot is not "a better laparoscopy than laparoscopy"; it is a tool that renders minimally invasive those operations that cannot be performed laparoscopically.

Whether cost-effectiveness and the surgeon-reported ergonomic benefit (surgeon health, career longevity) justify the added cost is hotly debated. The strength of evidence is moderate–high for robotic ≈ laparoscopic in standard repair (with added time/cost); in complex cases the debate continues.

Sources: Prabhu et al. (2020); Petro et al. (2021); Dhanani et al. (2021).

Mesh Technology

Prosthetic mesh reinforces the repair and thereby compensates for the biological collagen deficit (see Section 7). Mesh choice is defined along three axes — material, weight/pore size and absorbability — to which a fourth is added: the plane of placement (Section 18).

17.1 Material classes

Synthetic, non-absorbable (permanent) — polypropylene, polyester, ePTFE: The universal standard for clean elective repair. Macroporous, lightweight polypropylene is preferred in order to reduce stiffness and chronic pain while still preserving strength. Randomised data show that lightweight mesh markedly reduces the foreign-body sensation compared with heavyweight mesh. ePTFE warrants a specific warning: tissue integration is poor, infection resistance is low, and once infected it almost always has to be removed.

Biological — acellular dermal matrix, porcine small intestinal submucosa (SIS): These are scaffolds intended for remodelling and have historically been used in contaminated fields.

Bioabsorbable / hybrid — poly-4-hydroxybutyrate (P4HB), synthetic-biological hybrid constructs: These aim to provide temporary reinforcement during the remodelling process. They are of interest in contaminated fields and in young patients, but their long-term durability remains under scrutiny.

17.2 Current evidence — biological vs synthetic

In open groin repair, biological mesh shows no superiority: recurrence and chronic pain are similar, while seroma is more frequent and operative time longer (Bochicchio et al., 2016 meta-analysis) [1]. In open ventral repair the picture is even less favourable — a meta-analysis of randomised trials found that biological mesh resulted in more recurrences and more surgical site infections than synthetic mesh. The authors' conclusion is that the implant of choice in elective open ventral hernia repair is macroporous, uncoated synthetic mesh (Surgery, 2023) [25].

• Source 1 (evidence-weighted): The field is moving away from routine biological mesh in contaminated fields and, in many centres, towards synthetic or bioabsorbable options — because of the cost of biologics and their lower durability. At the meta-analytic level, biological mesh is associated with more recurrence and more infection.
• Source 2 (traditional teaching): Biological mesh "tolerates infected fields well" and has high infection resistance.

Synthesis: the statement in Source 2 reflects the field's historical rationale; Source 1 reports that randomised evidence largely fails to support that rationale. Biological mesh may indeed "tolerate" infection better in a contaminated field (that is, it may not need to be removed), but it does so at the cost of a markedly higher recurrence rate in the long term. Today's trend is the claim that bioabsorbable synthetics (P4HB) offer the best of both worlds — yet that claim is not yet supported by definitive randomised evidence. This is one of the field's most active open questions, and definitive RCTs are awaited.

Sources: Lockhart et al. (2018); Bochicchio et al. (2016); Surgery biological-vs-synthetic meta-analysis (2023).

Mesh Placement Planes

In ventral repair, where the mesh is placed is often more important than which mesh is used.

The consensus in the field has shifted clearly in favour of the retromuscular/sublay plane, and the mechanical rationale for this is rather elegant. In the retromuscular plane the intra-abdominal pressure itself presses the mesh against the fascia; that is, every cough the patient makes strengthens the repair rather than weakening it. With an onlay, the same pressure pushes the mesh away from the fascia.

In medium-sized (W2) ventral hernias the precise optimal plane remains debated; nevertheless, the retromuscular space is clearly preferred in current evidence because of its tissue-integration properties [20].

Complex Abdominal Wall Reconstruction (TAR and Component Separation)

Large, recurrent or contaminated ventral defects with loss of domain — most often those greater than 10 cm in width (W3) — require abdominal wall reconstruction (AWR). The aim is twofold: to restore a functional midline and to provide durable reinforcement.

19.1 Techniques

Anterior component separation (ACS; Ramirez). It relies on external oblique release and provides effective myofascial advancement. However, because it requires large skin flaps it carries high wound morbidity; in some series recurrence has reached as high as 32%.

Posterior component separation with transversus abdominis release (TAR; Novitsky et al., 2012). [14] It develops the retromuscular plane laterally beyond the linea semilunaris and creates a vast, well-vascularised space for a wide sublay mesh. Outcomes in the early series were as follows:

Because TAR requires no skin flaps, it has largely supplanted ACS; it thereby eliminates wound morbidity, the principal weakness of ACS.

19.2 Minimally invasive TAR

TAR is increasingly being performed minimally invasively/robotically in selected centres. This is precisely where the robot's real value in complex reconstruction lies (see Section 16.4).

Points of debate include the long-term durability of MIS-TAR compared with open TAR, and the optimal mesh choice in contaminated AWR. The strength of evidence is moderate (it rests largely on high-volume cohort/registry data; RCTs are limited). Looking ahead, the most needed items are RCTs comparing open vs robotic TAR with long-term recurrence and patient-reported outcomes, and standardised reporting through the Abdominal Core Health Quality Collaborative.

Loss of Domain and Preoperative Preparation Techniques

Loss of domain is the situation in which the contents of the hernia sac have grown too large to fit back into the abdominal cavity — in a sense, the formation of "a second abdomen". It is quantified on CT by calculating the ratio of hernia sac volume to peritoneal volume.

The solution lies in preoperative preparation:

These three methods can make fascial closure possible in giant hernias. Otherwise one is forced to bridge — the approach with the highest recurrence rate (see Section 18).

Prehabilitation

Prehabilitation is the structured optimisation of modifiable risk factors before surgery. In hernia surgery it must be regarded not as a "nice-to-have" add-on but as an intervention that directly determines the outcome. For the principal drivers of recurrence and surgical site infection are not the incision itself so much as the biological state in which the patient arrives on the operating table.

The targets before elective AWR are as follows:

Bariatric patients should undergo definitive weight-loss optimisation before elective AWR in order to reduce the risk of massive recurrence. The aim here is not to "turn the patient away" but to ensure the repair is durable. For a technically flawless repair performed in an unoptimised patient may yield a worse outcome than a technically mediocre but well-optimised one.

The strength of evidence in this area is moderate; while cohort data and guideline consensus are strong, target-specific RCTs are limited.

ERAS Protocols

ERAS (Enhanced Recovery After Surgery) pathways are multicomponent, evidence-based bundles that attenuate the surgical stress response, reduce opioid use and accelerate functional recovery.

In abdominal wall reconstruction the components of the bundle are as follows: multimodal, opioid-sparing analgesia; regional blocks — particularly the TAP block (transversus abdominis plane) ± liposomal bupivacaine; early oral feeding beginning on the day of surgery; early mobilisation, likewise including getting the patient up on the day of surgery; peripheral µ-opioid antagonists (alvimopan) to accelerate the return of bowel function; preoperative carbohydrate loading and avoidance of prolonged fasting; and minimising the use of nasogastric tubes and drains.

According to current evidence, an ERAS pathway in AWR has significantly improved postoperative pain, accelerated the return of bowel function and shortened hospital stay (Fayezizadeh et al., 2014) [4]. Today, ERAS bundles are accepted as standard in major abdominal wall surgery; they can even make safe same-day discharge possible after advanced robotic AWR. The benefit here is multifactorial; it is the bundle as a whole, not any single component, that delivers the improvement.

The strength of evidence is moderate (pilot and cohort data are strong; large hernia-specific RCTs are limited). Component-dismantling studies are needed in future to identify the highest-yield elements.

Postoperative Rehabilitation

A structured recovery guide both improves function and reassures the patient while protecting the repair.

The general principles are relatively simple. Early mobilisation is encouraged (walking on the day of surgery). After mesh-based tension-free groin repair, most guidelines permit a return to normal daily activity within days and to unrestricted activity within ~1–2 weeks. Return to work should be guided by pain and the physical demands of the job, not by arbitrary lifting restrictions; heavy manual workers may require a graded return. Complex AWR, by contrast, means a staged progression over weeks.

Modern evidence supports the principle of "activity as tolerated". Prolonged immobilisation offers no benefit whatsoever in terms of recurrence; it merely delays recovery. On the other hand, the precise optimal duration of lifting restrictions remains debated. Historically, "no heavy lifting for 4–6 weeks" was stipulated arbitrarily; modern guidelines increasingly favour symptom-guided progressive loading.

The typical recovery timeline after groin repair with mesh passes through the following stages: Day 0, Days 1–3, Days 3–7, Weeks 1–2, Weeks 2–4, Weeks 4–8, Week 8+ and complex AWR.

The strength of evidence in this area is moderate.

Outcomes: Recurrence

There are two dominant outcome domains — recurrence, and chronic pain/quality of life. This section addresses the first; the second is in Section 25.

In groin hernia, with mesh and adequate technique, recurrence is typically in the low single digits; with synthetic mesh in primary inguinal hernia it is on the order of <2% [20]. In incisional hernia the situation is markedly worse. Mesh reduced 10-year recurrence from 63% to 32% [2] — but 32% is still a high figure. This picture demonstrates that ventral/incisional repair is structurally more prone to failure than groin repair and that it benefits from optimised technique (sublay mesh, defect closure).

*Experience-dependent; in subsequent series of adequate volume it approaches the recurrence rates of open repair.

It is no longer possible to reduce the outcome measure to recurrence alone; assessment has shifted towards patient-reported outcomes (EuraHS-QoL, hernia-specific quality-of-life instruments) and registry-based comparison.

Outcomes: Chronic Postoperative Inguinal Pain (CPIP)

CPIP is defined as groin pain persisting for more than 3 months after surgery. A 2024 systematic review/meta-analysis found the pooled incidence of CPIP to be 17.0% (95% CI 12.8–21.7) (Zhou et al., 2024) [24]. The regional variability is striking:

This threefold difference most likely reflects differences in definition, measurement and reporting rather than any true biological difference — which is in itself striking evidence of the field's need for standardisation.

Looking at the severity distribution (Reinpold, 2017) [18], clinically significant CPIP affecting daily activity is seen in ~10–12% of patients, and debilitating pain in ~0.5–6%. There is also a marked difference according to approach:

The risk factors for CPIP with strong evidence are as follows [18,24]:

The practical meaning of this table is important. That the strongest predictors of CPIP are factors present before surgery (preoperative pain, previous repair, young age, female sex) has two consequences. First, informed consent is an obligation: a patient who is young, female, has preoperative pain or has undergone a previous repair must be told explicitly that the risk of CPIP is markedly above average. Second, the rationale for "preventive" repair in the asymptomatic patient is weakened — because operating on a patient with no pain at all means accepting a risk, of up to 10%, of giving that patient chronic pain. This is the strongest, yet least discussed, rationale for a watchful waiting strategy.

The fundamental knowledge gap here is likewise clear: there is no validated intraoperative strategy that reliably eliminates CPIP. Identifying and preserving the nerves, reducing fixation and using lightweight mesh are reasonable but unproven approaches.

Complications

Early complications include haematoma and seroma, surgical site infection (SSI) — more frequent in open anterior mesh repair than in endo-laparoscopic repair — urinary retention and ileus. There are also approach-specific patterns: visceral/vascular injury (particularly with TAPP), port-site hernia and more frequent seroma with laparoscopic/robotic repair; whereas scrotal haematoma and superficial wound infection predominate with open repair.

Late complications include recurrence, chronic pain (CPIP; see Section 25) and mesh-related problems (migration, erosion, infection, adhesion and, rarely, mesh removal — explantation).

Ischaemic orchitis or testicular atrophy may rarely occur in men. In emergency repair, the presence of strangulation entails markedly higher morbidity, bowel resection and mortality.

It is worth recalling one piece of context here: in the Fitzgibbons trial, roughly one third of surgically treated patients experienced a short-term complication (haematoma, infection); a small number of life-threatening events were observed [5]. This too is a fact that supports the logic of a watchful waiting strategy — surgery is not without its price either.

Sources: Reinpold (2017); Neumayer et al. (2004); Zhou et al. (2024); Simons et al. (2009).

Special Patient Populations

Women. Because the rate of femoral hernia and the risk of strangulation are higher, watchful waiting is not recommended; a laparoscopic/preperitoneal repair that also covers the femoral canal is preferred [7]. In addition, female sex is an independent risk factor for CPIP. This dual reality — both a more urgent need for repair and a higher risk of chronic pain — makes the consent process in female patients particularly demanding.

Elderly / frail patients. The risk–benefit balance must be individualised. Because emergency repair carries a markedly higher mortality, it is appropriate to support timely elective repair in fit older adults. An attitude of "let us not operate because the patient is old" may push the patient towards a far riskier emergency operation later on.

Obese patients. These patients carry an increased risk of incisional hernia and wound complications. Prehabilitation before elective AWR (weight loss, glycaemic and nutritional optimisation, smoking cessation) improves outcomes (see Section 21). In bariatric patients, definitive weight optimisation before elective AWR is mandatory in order to reduce the risk of massive recurrence.

Pregnant patients. Unless there is symptomatic incarceration, repair should be deferred until after delivery. Postpartum rectus diastasis, on the other hand, requires separate assessment.

Athletes / "sports hernia" (athletic pubalgia). This is a distinct entity and not a true hernia. Rehabilitation is applied first; surgery comes into play selectively. MRI is useful for diagnosis and differential diagnosis.

Children. Paediatric groin hernia is almost always indirect (a patent processus vaginalis). Treatment consists of high ligation ± laparoscopic repair; mesh is not used. CPIP is rare (~3%) but is a recognised condition.

Contaminated / emergency fields. Mesh choice (synthetic vs bioabsorbable vs biologic) and staged strategies are individualised. Recent evidence supports synthetic/bioabsorbable over biologic in many contaminated VHR settings (see the contradiction box in Section 17).

Across these populations as a whole the strength of evidence is moderate; population-specific RCTs are limited.

Emergency Hernia Surgery

Management follows a defined sequence. Resuscitation comes first (fluids, electrolytes, nasogastric decompression, broad-spectrum antibiotics); emergency surgical exploration then follows — because delay means bowel necrosis. At exploration, bowel viability is assessed and resection performed if required; finally, the hernia repair is carried out.

At this point a critical question arises: should mesh be used in an emergency, contaminated field? The WSES (World Society of Emergency Surgery) guidelines state that mesh is frequently safe in clean-contaminated emergency repair. However, where there is frank contamination (bowel perforation, dirty field), the decision is individualised; pure tissue repair, bioabsorbable mesh or a staged strategy (temporary closure → subsequent definitive repair) should be considered.

In terms of outcomes, emergency repair carries markedly higher morbidity and mortality than elective repair. This is the strongest justification for timely elective repair in suitable patients — and it explains why watchful waiting is not recommended in femoral hernia in particular.

Artificial Intelligence and Emerging Technologies

Artificial intelligence and digital surgery are entering the entire perioperative pathway of hernia care. The great majority of applications, however, remain at an early stage:

Most of these tools remain investigational; the fundamental gap is prospective validation and a prospectively demonstrated impact on outcomes. The strength of evidence is therefore low for now (at the level of proof of concept), yet the field is evolving rapidly.

Tissue Engineering and Regenerative Medicine

Tissue engineering

The aim here is to replace inert prostheses with scaffolds that regenerate a functional abdominal wall. The principal directions are electrospun and composite scaffolds, cell-seeded decellularised matrices, and growth-factor-releasing meshes designed to improve integration and reduce the chronic foreign body response. The goal is clear: mechanical support during remodelling, followed by durable native tissue.

The strength of evidence is low (preclinical/early clinical); data at the level of mature RCTs do not yet exist. The core debate is whether engineered constructs can ever match the durability of synthetic mesh.

Regenerative medicine

Regenerative medicine, rather than bridging the gap mechanically, aims to target the underlying collagen/ECM defect directly (see Section 7). Directions include mesenchymal stromal cell (MSC) therapies, augmentation with platelet-rich plasma (PRP), biomaterials designed to normalise the type I : type III collagen balance and MMP activity, and stem cell-seeded biologic scaffolds intended to regenerate autologous fascia without leaving a permanent foreign body.

The conceptual appeal of this approach comes from the fact that the collagen abnormality persists systemically even after repair [9]; no existing mesh corrects this underlying defect, it merely compensates for it. The strength of evidence, however, is low (experimental). The real challenge in the coming period is to translate this into a durable clinical benefit and to select patients according to their collagen biomarker profile; biomarker-stratified early-phase studies will be the first step along this path.

Ongoing Clinical Trials

The most striking entry in this table is prophylactic mesh. Given that incisional hernia develops in 10–15% of patients after midline laparotomy [20], placing prophylactic mesh at the index laparotomy in high-risk patients is a conceptually powerful idea and is currently one of the most active randomised research questions in the field. This may be the first genuine example of hernia surgery moving from treatment to prevention.

International Guidelines and the Implementation Gap

Key documents

The HerniaSurge International Guidelines for Groin Hernia Management (2018) [7] is the most comprehensive groin hernia guideline in the field: 165 pages, 88 recommendations, ~1,300 references. It has been endorsed by all continental hernia societies and by EAES, was developed using GRADE methodology, and was updated in 2023 (10 sections; Stabilini et al., BJS Open) [20].

On the EHS (European Hernia Society) side, three key documents stand out: the groin hernia guideline that has attracted more than 2,480 citations (Simons et al., 2009); the midline incisional hernia guideline that standardises defect assessment and the use of component separation (Sanders et al., 2023, BJS); and the EHS ventral classification (Muysoms et al., 2009) [11]. In addition, there are documents from SAGES (laparoscopic ventral hernia; Heniford, 2016), EAES, the American Hernia Society (AHS), IEHS, WSES (emergency surgery) and national bodies such as NICE.

The implementation gap

Despite the existence of strong guidelines, real-world adherence is variable. For example, the rate of laparoscopic approach use in appropriate indications has been reported in some surveys as below ~42% [20].

This is the least discussed but probably the largest quality gap in the field: the problem is not a lack of knowledge, but the failure to apply that knowledge. Behind it lie access to equipment, the steepness of the learning curve (~250 cases), reimbursement structures and habits within surgical training.

Evidence Comparison (GRADE Synthesis)

Certainty varies markedly from question to question. The strongest evidence supports the superiority of mesh over suture and the safety of watchful waiting in men; robotic–laparoscopic equivalence is of moderate certainty; while tissue engineering and regenerative approaches are of low certainty and experimental.

Contradictions Between the Two Source Reviews

This review has been blended from two independent evidence syntheses. The sources diverge on the points below; rather than reducing them to a single figure, both have been reported.

Cost-Effectiveness

The critical aspect of the cost-effectiveness calculation is that it changes according to whose budget is paying. From the hospital perspective, open Lichtenstein is the cheapest option. From the societal and employer perspective, the rapid return to work after laparoscopic repair may offset the equipment cost — particularly in working, active adults. Robotic surgery, by contrast, demonstrates superiority from no perspective in standard cases; it has to base its justification on complex reconstruction and surgeon ergonomics.

Research Gaps

1. Prevention of chronic pain: there is no validated intraoperative strategy that reliably eliminates CPIP. Mechanism-based prospective studies are required; this is the single largest gap in the field.
2. The robotic value proposition: long-term, multicentre RCTs that incorporate cost — particularly in complex reconstruction, where the theoretical advantage of the robot is greatest.
3. Mesh in contamination: definitive RCTs comparing synthetic, bioabsorbable and biologic mesh in contaminated fields (see Section 34).
4. Ventral recurrence: 32% recurrence at 10 years even with mesh repair — durable solutions remain an unmet need.
5. Biomarker-guided care: translating collagen/genetic profiling into individualised mesh and technique selection.
6. The optimal plane in medium-sized (W2) ventral hernia: although the retromuscular space is preferred, definitive evidence is lacking.
7. The optimal duration of lifting restrictions: still arbitrary; symptom-guided loading protocols must be validated.
8. Global surgery: outcomes and access in low-resource settings; the outcomes of task-shared mesh repair.
9. Prophylactic mesh: the true benefit–harm balance of prophylactic mesh at high-risk index laparotomy.

Future Treatment Directions

The prominent themes of the coming period can be grouped along a few axes. On the mesh side, next-generation lightweight, macroporous, bioabsorbable and hybrid constructs with better integration and a lower chronic pain profile are arriving, as are 3D-printed, patient-specific meshes perfectly adapted to the patient's preoperative cross-sectional imaging — these are the likely next wave of precision reconstructive surgery. At the preclinical level, work is under way on "smart" meshes incorporating nanotechnology biosensors for real-time infection monitoring and fascial tension sensing.

Turning to the biologic front, regenerative augmentation targeting the collagen defect (scaffolds and cellular/biologic therapies) stands out. On the digital surgery and AI side, validated risk prediction, imaging analytics and intraoperative guidance embedded in registry ecosystems are developing. Three trends frame all of this: personalised surgery, in which approach, mesh and prehabilitation are matched to individual risk (defect, contamination, biology, surgeon volume); structured metabolic and mechanical optimisation becoming standard before major AWR; and a shift towards prevention with prophylactic mesh at high-risk laparotomy, aiming to stop the hernia from forming rather than to treat it.

Final Conclusions

Hernia repair is a high-volume, high-impact field in which forty years of randomised evidence have produced durable and applicable principles. These principles can be gathered under four headings.

First, mesh reinforcement reduces recurrence — and this holds even in small defects, because the problem is not the diameter of the hole but the quality of the tissue. Second, watchful waiting is safe but in most men does not prevent surgery, it merely defers it; in women and in femoral hernia it is not appropriate. Third, in the hands of experienced surgeons, minimally invasive repair reduces pain and speeds recovery without compromising durability — the technique and the surgeon cannot be separated from one another. Fourth, although the robotic platform has spread rapidly, it has failed to demonstrate a clear patient-level benefit in standard repair and has added time and cost; its promise is concentrated in complex reconstruction.

The centre of gravity of the field has shifted away from recurrence alone towards a patient-centred model in which chronic pain and quality of life predominate. Alongside this, individualised technique selection, prehabilitation, ERAS and registry-based quality improvement come to the fore. The frontiers that will define the coming decade are clear: prevention of chronic pain, next-generation and regenerative meshes, biomarker-guided personalisation, and rigorous robotic trials that incorporate cost.

Beyond all of this, however, the strongest levers on outcome have not changed: the surgeon's operative volume and a standardised, patient-tailored technique.

Plain-Language Patient Guide

A plain-language summary for informed patients. This section is not a substitute for individual advice from a surgeon who knows you.

What is a hernia?

A hernia is an organ or tissue pushing outwards through a weak point in the abdominal wall; it most often appears in the groin. People tend to picture it as a "hole", but the real problem is usually a weakness in the tissue itself. That is also why mesh is used even for small hernias.

Do I need surgery straight away?

If you are a man with no symptoms or very mild ones: watchful waiting is a safe option. Even so, because symptoms tend to increase over time, most people are operated on sooner or later (roughly more than half within 10–12 years).

If you are a woman, if you have a femoral hernia, or if your hernia is painful or getting bigger: repair is recommended and waiting is not the right choice.

When should I go to hospital URGENTLY?

Go to the emergency department immediately if you have any of the following:

• A lump that suddenly becomes painful and hard and can no longer be pushed back in
• Vomiting, abdominal bloating, or inability to pass gas or stool alongside it
• Fever, or a change in the colour of the skin over the lump (redness, bruising)

Which operation?

Open repair (Lichtenstein mesh repair) and keyhole/laparoscopic repair are both excellent techniques.

The keyhole approach usually means less pain and a faster recovery; it is preferred for hernias on both sides and for hernias that have come back after previous surgery.

But there is one condition: your surgeon must be experienced in that technique. This is the clearest message in the whole literature — the surgeon's experience determines the outcome far more than the technique does.

The open approach can even be performed under local anaesthesia, whereas the keyhole approach requires general anaesthesia.

Is mesh safe?

Yes — and it greatly reduces the chance of the hernia coming back. Mesh is now standard in most repairs. In incisional hernia, recurrence at 10 years is 63% with suture repair alone, falling to 32% with mesh.

You may have heard concerns about mesh. The honest picture is this: mesh markedly reduces recurrence, and in return there can rarely be mesh-related problems (infection, chronic discomfort). On the evidence, the balance of benefit and harm clearly favours mesh.

Is robotic surgery better?

For standard hernias, no. Two large, high-quality trials (RIVAL and PROVE-IT) showed that robotic surgery offers patients no clear advantage over laparoscopic surgery — and it takes longer and costs more.

The real value of the robot lies in complex, major abdominal wall reconstruction. In other words, asking for "the robot" will not give you a better outcome in an ordinary groin hernia.

How long does recovery take?

Most groin repairs are day-case procedures; you go home the same day.

Risks you should know about

• Temporary bruising and swelling (common, settles on its own)
• Infection (rare)
• Chronic groin pain — this is the single most important topic to discuss openly. Roughly 1 in every 10 patients may develop long-lasting groin pain severe enough to affect daily life.

If your risk is above average, you should know it. The risk of chronic pain is higher in the following situations:

• If you already had pain before the operation (2.3-fold)
• If you have had previous hernia surgery on the same side (2.7-fold)
• If you are young (2.3-fold)
• If you are a woman (1.9-fold)

This also explains why the decision to have surgery "just in case" for a painless hernia needs careful thought: you may go into the operation with no pain at all and come out with chronic pain.

How can you improve your own outcome?

These are within your control, and their effects are genuinely large:

1. Stop smoking — at least 4 weeks before surgery. This is not negotiable. Smoking directly impairs tissue healing and collagen production, and markedly increases the risk of infection and recurrence.
2. Get your blood sugar under control (target HbA1c < 7.5% if you have diabetes).
3. Lose weight (especially if major abdominal wall surgery is planned). This is not about "postponing" the operation, but about making the repair last.
4. Choose a high-volume surgeon or centre. This is the most consistent finding in the literature.

Glossary

Abbreviations

References

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