EUROPEAN TISSUE REPAIR SOCIETY

TISSUE ENGINEERING IV

A PROSPECTIVE BLIND RANDOMISED TRIAL COMPARING COLLAGEN MESH WITH POLYPROPYLENE MESH IN PRIMARY INGUINAL HERNIA REPAIR: AN INTERIM REPORT

PRIMARY inguinal hernia repair using a polypropylene mesh was advocated by Lichtenstein¹ in 1990 in a series of more than 5,000 hernia repairs over 25 years. It has subsequently been adopted as the current gold standard according to the National Institute of Clinical Excellence, the Cochrane Collaboration² and the EU Hernia Trialists Collaboration.³

There are, however, significant complications associated with the use of polypropylene mesh because it acts as a permanently implanted foreign body and is therefore prone to chronic infection or rejection. Taylor et al.⁴ conducted a postal vote of surgeons in the west of Scotland and reported a chronic groin sepsis rate of at least 0.1% that invariably resulted in removal of the mesh. Studies by Sakorafas et al.⁵ and Foschi et al.⁶ have described late rejection of the mesh with no causative organism identified in 0.1% – 0.4% of patients. In addition, there have been case reports of mesh shrinkage leading to hernia recurrence⁷ or chronic pain.⁸

There are theoretical benefits of using an implantable collagen mesh (Figure 1) over polypropylene mesh in that it is incorporated into the host tissue and therefore may be more resistant to chronic infection and the response to antibiotics may be similar to host tissue rather than a foreign body (Figure 2). Also, collagen is only weakly immunogenic and therefore foreign-body reaction and rejection is unlikely. Collagen mesh has not been found to shrink in in vivo studies.

The collagen mesh used in our study was Permacol™ surgical implant which is acellular cross-linked porcine dermal collagen and its constituent elastin fibres supplied by Tissue Science Laboratories plc.

Figure 1. Collagen mesh in situ in inguinal hernia repair.

Figure 2. Collagen mesh graft incorporated in to subcutaneous tissues in a canine model.

Methods

Sequential patients undergoing primary unilateral hernia repair under general anaesthesia were randomised to receive either a polypropylene or a collagen mesh. The protocol for open hernia repair was standardised and both the patient and the researcher involved in the follow-up of patients were blinded as to which mesh was inserted.

The properties of the mesh were graded by the surgeon in terms of ease of handling, insertion and suturing. Data were collected from the patient pre-operatively using the SF36 and Euroqol questionnaires and again at 4 weeks, 3 months and 1 year post-operatively. A research nurse documented complications and pain scores at these follow-up appointments.

Statistical analysis was performed using t-test and Mann Whitney test for parametric and non-parametric data respectively.

Results

140 patients, 136 of them male, were randomised. 59% of hernias were-right sided. 78 (56%) patients received collagen and 62 (44%) polypropylene mesh respectively.

Surgical Properties
Data on surgeon opinion of insertion, ease of handling and ease of suturing were missing for 11 cases (collagen n = 71, polypropylene n = 58). For each of these three variables the option answers were 1 (easy to handle) to 10 (very difficult to handle). Treating the data as continuous for this analysis, a two-sample t-test was carried out to compare each variable by the mesh used. No significant differences were found by type of mesh for suturing, insertion or handling (all p > 0.05).

Complications
The complications following surgery are shown in Figure 3 and were analysed using the Mann Whitney test because of small numbers or no cases for some items. There was no significant difference in the rates of infection or recurrence at either 3 months or 1 year. The infected polypropylene mesh at 3 months persisted to 1 year and required subsequent removal whereas a similar case at 3 months with collagen mesh resolved on antibiotics. There was a significantly increased risk of haematoma formation in the 3 months following polypropylene mesh repair compared to collagen mesh repair (p = 0.048).

Figure 3. Complications following mesh repair of primary inguinal hernias.

Figure 4. Pain scores following mesh repair of primary inguinal hernias.

Pain Scores
There was no significant difference in the pain perceived between the two mesh types at 4 weeks, 3 months or 1 year post-operatively (Figure 4).

Quality of Life: Euroqol Score
As would be expected for anyone undergoing surgery there was an initial non-significant decrease at 4 weeks in both groups and thereafter a significant increase compared to the pre-operative score. There were, however, no significant differences between the 2 mesh types.

Quality of Life: SF36 Questionnaire
There was a significant decrease in physical (p = 0.016) and social (p = 0.003) function at 4 weeks in both groups consistent with the post-operative period. There was a significant difference in physical activity score at 3 months in the collagen mesh group but there was no significant difference by 1 year.

Discussion and Conclusions

The use of collagen mesh resulted in fewer post-operative haematomas compared to polypropylene mesh. One hypothesis to explain this observation would be that collagen activates the clotting cascade and this has formed the basis of additional research. There was a suggestion that patients recovered physical activity slightly more quickly in the polypropylene mesh group but this was not significant at 1 year follow up.

Collagen is as effective as polypropylene mesh without the risks of a permanently implanted foreign body and it is proposed to recruit 200 patients to the study and undertake follow-up for 5 years post-operatively.

References

• Lichtenstein IL, Shulman AG, Amid PK. Use of mesh to prevent recurrence of hernias. Postgrad Med 1990; 87:155–8: 160.
• Grant AM. Open mesh versus non-mesh repair of groin hernia meta-analysis of randomized trials based on individual patient data. Hernia 2002; 6: 130–6.
• Collaboration EHT. Mesh compared with non–mesh methods of open groin hernia repair: systematic review of randomized controlled trials. Br J Surg 2000; 87: 854–9.
• Taylor SG, O’Dwyer PJ. Chronic groin sepsis following tension-free inguinal hernioplasty. Br J Surg 1999; 86: 562–5.
• Sakorafas GH, Halikias I, Nissotakis C et al. Open tension free repair of inguinal hernias; the Lichtenstein technique. BMC Surg 2001; 1: 3.
• Foschi D, Corsi F, Cellerino P, Trabucchi A, Trabucchi E. Late rejection of the mesh after laparoscopic hernia repair. Surg Endosc 1998; 12: 455–7.
• LeBlanc KA. Complications associated with the plugand- patch method of inguinal herniorrhaphy. Hernia 2001; 5: 135–8.
• Schumpelick V, Arlt G, Schlachetzki A, Klosterhalfen B. [Chronic inguinal pain after transperitoneal mesh implantation. Case report of net shrinkage]. Chirurg 1997; 68: 1297–300.

Authors:
Chris Macklin, Peter Moore and Katherine Dent
Scunthorpe General Hospital, Lincolnshire, UK
Lorraine Foster
Commission for Health Improvement, UK
Jean Peters
University of Sheffield, Yorkshire, UK