A Critical Remark on Surgical Collagen Implants

When I had the privilege to review the work by Nezhad et al on CorMatrix for aortic valve replacement, I estimated that it might be of some value for thoracic and cardiac surgeons to share the experience with these products in hernia repair. At first sight this may sound a little far-fetched as one would suppose that these fields have little in common. However, when collagen implants (and porcine small intestine submucosa was among the first on the market) entered the hernia scene around 2005, they were by no means new. On the contrary, studies from trauma, vascular, plastic, ophthalmological, and rhinopharyngeal surgery date back almost 20 years. In retrospective, it must be admitted that collagen implants were not introduced to hernia surgery because of their great success in the mentioned applications, where they rather proved to be a failure. As an unlucky consequence, companies identified hernia repair as a new potential market with a seemingly low risk for complications. It is almost needless to say that the arguments for using collagen implants have been the same for every indication. The promise of biodegradability, reduced foreign body reaction, fast tissue ingrowth, inherent bacterial clearance, and remodeling superior to synthetic grafts (vascular), autologous tissue (plastic, trauma), or meshes (hernia) was willingly accepted by the surgical community. Did these promises materialize for any collagen implant, regardless of origin (bovine, porcine, human) or specifications (cross-linked, non cross-linked, multi-/monolayer) in hernia repair? The answer is simply “no”.[1]

Apart from breast reconstruction, in which a breakdown of mechanical strength is acceptable as it contributes to the shaping and cosmetic result, and in which local reaction is more favorable, collagen implants are on a steep decline. This is especially true for hernia repair where the “biologic mesh” market was a multimillion dollar business only several years ago, while today it is not unlikely that collagen implants will vanish from the hernia stage altogether.

The reasons are clear-cut: the behavior of collagen implants in the abdominal wall is unpredictable and generally inferior to classical polypropylene or polyester meshes in terms of tissue integration, foreign body reaction, and tolerance to enzymatic attack in clean/contaminated wounds.

So coming back to the point why this commentary by a hernia surgeon might be useful in this context, let me frankly say that the histological features described by Nezhad et al precisely reflect the leading causes for severe complications in both experimental and clinical settings in hernia surgery and other fields. Fragmentation, thickening, chondroid metaplasia are just pieces of the picture called “severe foreign body reaction”, and although I appreciate the preliminary character of the work, I humbly advise my colleagues from thoracic and cardiac surgery to critically observe and reflect upon the proceedings with collagen implants in their area of expertise and to take a brief look at the abundant literature available from other surgical specialties.[2] Finally, I want to congratulate the authors for their clearness in presenting their results, although, for given reasons, I would be cautious with some aspects of their conclusions.

• References

• 1 Petter-Puchner AH, Dietz UA. Biological implants in abdominal wall repair. Br J Surg 2013; 100 (8) 987-988
• 2 Guillaume O, Teuschl AH, Gruber-Blum S, Fortelny RH, Redl H, Petter-Puchner A. Emerging trends in abdominal wall reinforcement: bringing bio-functionality to meshes. Adv Healthc Mater 2015; 4 (12) 1763-1789