title: Novel biological strategies in the management of anal fistula.
abstract: BACKGROUND
  The mostly widely studied biomaterials for the sphincter sparing treatment of anal fistulas are fibrin glue and the anal fistula plug (AFP). However their overall mean clinical success is only 50-60%. As the understanding of the pathology of anal fistula, wound healing and the host response to materials has improved, so new biological sphincter-sparing strategies have been developed. The aim of this review is to assess the safety and efficacy of these novel techniques.
  
  
  METHODS
  PubMed, the Cochrane database and EMBASE were independently searched. All studies that investigated the potential of a biomaterial (defined as any synthetic or biologically derived substance in contact with host tissue) to augment the healing of anal fistula without sphincter division were included. Studies solely describing the role of fibrin glue or an AFP were excluded. Data extraction included type of material, fistula aetiology, treatment of the primary tract, fistula healing, incontinence, duration of follow-up and any specific complications. Systematic quality assessment of the included articles was performed.
  
  
  RESULTS
  Twenty-three articles were finally selected for review. These included a variety of biological and synthetic systems that were employed to deliver selected components of the extracellular matrix, growth factors, cytokines, stem cells or drugs to the fistula tract.
  
  
  CONCLUSIONS
  To date no study matches fistulotomy with regard to long-term fistula eradication rate. This is probably due to implant extrusion, inadequate track preparation or an unsuitable material. Future techniques need to address all these issues to ensure success. Success should be validated by MRI or long-term follow-up.
authors.affiliation: Department of Surgery, Homerton University Hospital, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Lewis
authors.forename: P J
authors.initials: PJ
authors.lastname: Lunniss
authors.forename: T M
authors.initials: TM
authors.lastname: Hammond
mesh_terms: D062088:Acellular Dermis; D001003:Anal Canal / Q000502:physiology*; D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D003487:Cyanoacrylates / Q000627:therapeutic use; D016207:Cytokines / Q000627:therapeutic use; D005109:Extracellular Matrix / Q000637:transplantation; D006801:Humans; D008863:Microspheres; D059351:Organ Sparing Treatments; D011506:Proteins / Q000627:therapeutic use; D012003:Rectal Fistula / Q000628:therapy*; D033581:Stem Cell Transplantation
chemical_list: C472676:Bio-glue; D001672:Biocompatible Materials; D003487:Cyanoacrylates; D016207:Cytokines; D011506:Proteins