Where to place mesh in open primary inguinal hernia repair. Preliminary results of a prospective randomized trial. Morrison JA; Mahoney D; Trinh T; Chatham Kent Health Alliance Chatham. ON

INTRODUCTION  There are between 750,000 and 1 million inguinal hernia repairs carried out in N. America every year.  20 million inguinal hernia operations world wide.  2% - 30 % complain of long term groin pain following mesh repair.  Some are completely life-style disabled.  WHY ?

Causes of postoperative groin pain Neuropathic Local causes Amid. P.K Hernia 2004

Ideal mesh properties  Non carcinogenic  Chemically Inert  Resistant to mechanical strain  Can be sterilized  Inert to body and tissue fluids  Limited foreign body reaction in host  Can be fabricated in the necessary form  Unlikely to produce allergy or sensitivity reaction  Resist Infection  Provide a barrier to adhesions on the visceral side Cumberland. Med. J. Aust (1) Scaler JT Proc. Royal Soc. Med Bendavid R. Springer 2001

Polypropylene Mesh Covidien Parietene Progrip Mesh  Macroporous medium weight polypropylene mesh  Incorporated polylactic acid “ Hooks”  Hooks dissolve in approx. 70 days  No sutures required for fixation

Post operative pain Chronic groin is defined as pain lasting longer than 3 months following operation. Can occur in up to 30% of patients following mesh repair. We postulated that some of this chronic groin pain might be relieved if the spermatic cord and its structures could be isolated from the mesh.

Study Design Based on the premise that ingrowth of tissue occurs from structures lying both sides of an implanted mesh. Inflammatory reaction occurs in tissue on both sides of the mesh. In this case, from the transversalis fascia posteriorly and from the spermatic cord anteriorly. Study registered at NIH, Washington D.C. Identifier # NCT NO INDUSTRY INPUT OR SUPPORT

Patient Cohort The study was open to all male patients 20 years or older. Inguinal hernias must be primary in nature No bilateral hernias No other concurrent intra – abdominal procedures The procedure was explained to all patients, and detailed consent obtained.

Design A PRT was designed by statisticians. Randomization was attained by computer Index Cards indicating whether the cord was to be “ In Contact” or “ Isolated “ from the mesh were placed in envelopes in exact randomized order. The envelope was opened when the mesh was ready for insertion.

IN CONTACT operation Routine open Lichtenstein herniorrhaphy was carried out, in those cases where the mesh was indicated to be in contact with the cord. NO fixation sutures were used NO neurectomy was carried out intentionally. The inguinal ligament was routinely closed over the cord.

ISOLATED operation The HALSTED procedure was employed to isolate the spermatic cord from the mesh. In this procedure, the inguinal ligament is placed behind the cord, and repaired as normal, except a NEW external inguinal ring must be fashioned to prevent cord strangulation. This completely isolates the cord from lying on the mesh as it traverses the inguinal canal, on its way to the scrotum.

Study Arms  ISOLATED n = 36  CONTACT n = patients lost to follow up

Interim Results TABLE “A” N= 90 Age : 22 years – 89 years Mean = 56.4 yrs. BMI: 16.8 – 32.5Mean = 25.8 Operative time: 18 mins – 80 mins Mean = 32 mins Length of follow up : 3 mts – 36 mts Mean =23 mts.

Table B COPD:9 DIABETES:6 SMOKERS:26 41 / 89 patients with serious co-morbidity

Table C Adverse events intra operatively = 1 Mesh Infection = 0 Recurrences = 1 Carolinas Comfort Scale at 3 months.

Carolinas Comfort Scale

Pain score at 3 months Isolated spermatic cord Mesh in contact with the spermatic cord P = unpaired t parametric P = Wilkinson 2 non parametric