title: The clinical status of cartilage tissue regeneration in humans.
abstract: OBJECTIVE
  To provide a comprehensive overview of the basic science and clinical evidence behind cartilage regeneration techniques as they relate to surgical management of chondral lesions in humans.
  
  
  METHODS
  A descriptive review of current literature.
  
  
  RESULTS
  Articular cartilage defects are common in orthopedic practice, with current treatments yielding acceptable short-term but inconsistent long-term results. Tissue engineering techniques are being employed with aims of repopulating a cartilage defect with hyaline cartilage containing living chondrocytes with hopes of improving clinical outcomes. Cartilage tissue engineering broadly involves the use of three components: cell source, biomaterial/membranes, and/or growth stimulators, either alone or in any combination. Tissue engineering principles are currently being applied to clinical medicine in the form of autologous chondrocyte implantation (ACI) or similar techniques. Despite refinements in technique, current literature fails to support a clinical benefit of ACI over older techniques such as microfracture except perhaps for larger (>4 cm) lesions. Modern ACI techniques may be associated with lower operative revision rates. The notion that ACI-like procedures produce hyaline-like cartilage in humans remains unsupported by high-quality clinical research.
  
  
  CONCLUSIONS
  Many of the advancements in tissue engineering have yet to be applied in a clinical setting. While basic science has refined orthopedic management of chondral lesions, available evidence does not conclude the superiority of modern tissue engineering methods over other techniques in improving clinical symptoms or restoring native joint mechanics. It is hoped further research will optimize ease of cell harvest and growth, enhanced cartilage production, and improve cost-effectiveness of medical intervention.
authors.affiliation: Department of Orthopaedic Surgery, University of Toronto, Toronto, Ontario, Canada. Electronic address: brent.mollon@mail.utoronto.ca.
authors.forename: B
authors.initials: B
authors.lastname: Mollon
authors.forename: R
authors.initials: R
authors.lastname: Kandel
authors.forename: J
authors.initials: J
authors.lastname: Chahal
authors.forename: J
authors.initials: J
authors.lastname: Theodoropoulos
mesh_terms: D001182:Arthroscopy; D002357:Cartilage Diseases / Q000601:surgery*; D002358:Cartilage, Articular / Q000166:cytology / Q000601:surgery*; D017690:Cell Transplantation / Q000379:methods; D019902:Chondrocytes / Q000637:transplantation*; D053595:Embryonic Stem Cells / Q000166:cytology; D048091:Guided Tissue Regeneration / Q000379:methods*; D006801:Humans; D051457:Hyaline Cartilage / Q000166:cytology / Q000601:surgery; D059630:Mesenchymal Stem Cells / Q000166:cytology; D023822:Tissue Engineering / Q000379:methods*; D014182:Transplantation, Autologous / Q000379:methods
keywords: Autologous chondrocyte implantation; Cartilage; Chondrocytes; Tissue engineering