Inguinal hernia repair-Challenges beyond zero recurrence.

Experiential history of inguinal hernia treatment parallels the history of surgery and continues to challenge the contemporary surgeon. We have come a long way from the era of tightly fitting bandages advocated by Hammurabi of Babylon and Moses ben Maimon.[1] Surgical march, halted temporarily by the anti-surgeon decree of the Roman Church, got an impetus during renaissance, to be crowned by the successful surgical repair (with < 10% recurrence) based upon anatomical exposition by Edoardo Bassini while he was recuperating from a post-traumatic fecal fistula. [2] Practice of surgery has marched from being merely life or limb preserving to being an enhancer of postoperative quality of life. Patient reported outcomes (PRO) have always taken precedence over clinical outcomes and encouraged surgeons to innovate.[3].

Theodre Bilroth foresaw the possibility of a radical cure of hernia repair premised upon development of an artificial tissue having density of fascia and toughness of a tendon. The introduction of polypropylene prosthesis (PPP) by Francis Usher, ushered in an era of progressively falling recurrence rates till Lichtenstein reported near zero recurrence with tension free PPP implantation, making PPP the most common prosthesis in practice of surgery. Success with PPP is attributed to formation of a mesh aponeurosis scar tissue (MAST) complex.[4] Inflammatory response induced by PPP is integral to MAST complex formation, but continuation of inflammation beyond MAST formation has raised fresh concerns beyond recurrence. Markers of inflammation continue to play around for years in the PPP implanted tissues around inguinal region.[4]

Recurrence, the index of clinical outcomes in hernia surgery, continues to be beaten down by implantation of PPP. In this era of universal PPP implantation recurrence is attributed to technical factors and surgical failure.[4] The debate is now about potential PPP induced insult to structures contiguous to inguinal region. Insult to testicular vasculature, adjoining nerves and vas can lead to ischemic orchitis and even atrophy. [5] Myelin degeneration, endoneuronal/perineuronal edema, fibrosis, and axonal loss can be induced by PPP leading to chronic neuropathic inguinodynia.[4] Entrapment of vas in MAST cicatrix can impair the vas mobility and intraluminal motility leading to obstructive azoospermia apart from dysejaculation.[45] Post-herniorrhaphy secondary infertility in males cannot be wished away despite the lack of randomized trials which are not possible due to ethics of obtaining preoperative semen parameters.[5] All these concerns are real and attributable to continuing inflammation post- MAST complex formation.

Hence a rethink on PPP is always welcome as attempted by Khan N et al.[6] The possible areas of improvement in PPP relate to size, shape, mass, fabric, design and architecture of the mesh. Tailoring the shape and size has not helped much.[1] Reducing the mass of PPP seems most promising in improving PROs. Potential changes in PPP design/ architecture have made our operating room into competing arenas for the prosthesis manufacturing industry. Lack of scientific studies to provide a well-informed recommendation about the choice of mesh creates a wide discretionary playground for the surgeon who can be influenced by the competing manufacturers.[4] Meshes have even been considered a mechanical overkill.[4] It is with this background that an endeavor by Khan N et al.,[6] to study the PROs with reduced mass PPP needs notice. In this era of informed and increasingly litigious society[7] improving PROs is more than desirable. Even our areas of ignorance like impact of PPP on ejaculation and fertility need to be communicated in true spirit of informed consent.[7] Reduced mass PPPs should moderate and attenuate the "continuing inflammation" hence improve the PROs. Larger pore size in reduced mass PPPs has shown to impede myofibroblast interlinkages.[4] Hence the possibility of mesh contraction and entrapment of contiguous structures in the cicatrix is substantially reduced. More studies are needed to settle the debate between mesh integration with abdominal wall compliance preservation versus mesh contraction and cicatrisation.

Technological advances following the Moore's Law have opened new vistas for the future road map of surgery. It will be possible in future to implant a PPP or an alternative mesh specifically customized to address individualized PROs. Claytronics might make it possible to weave an in vivo mesh in situ from a needle puncture guided by endoscopic vision and technological convergence of Imagineering.[8] Journey from Hammurabi to Bassini to Usher to Lichtenstein has been rewarding for the surgeon and his patient but not totally smooth. Betterment of PROs is a surgical continuum. Mesh fabric, design and architecture will continue to evolve aided by evolving scientific thinking amidst the plethora of emerging technologies.