title: A comparative study of 3 different cartilage repair techniques.
abstract: OBJECTIVE
  The value of cell-free techniques in the treatment of cartilage defects remains under debate. In this study, cartilage repair of full-thickness chondral defects in the knees of Goettinger minipigs was assessed by treatment with a cell-free collagen type-I gel or a collagen type-I gel seeded with autologous chondrocytes. As a control, abrasion arthroplasty was included.
  
  
  METHODS
  In 18 adult Goettinger minipigs, three full-thickness chondral defects were created in one knee of the hind leg. They were either treated with a cell-free collagen gel, a collagen gel seeded with 2 × 10(5)/ml chondrocytes, or left untreated. All animals were allowed unlimited weight bearing. At 6, 12, and 52 weeks, 6 animals were sacrificed. Immediately after recovery, a non-destructive biomechanical testing was performed. The repair tissue quality was evaluated histologically, and the O'Driscoll score was calculated.
  
  
  RESULTS
  After 6 weeks, a high number of cells migrated into the initially cell-free collagen gel. After 1 year, a hyaline-like repair tissue in both groups has been created. As assessed by O'Driscoll scoring and col-II staining, repair tissue quality of the initially cell-free gel was equal to defects treated by cell-seeded collagen gel implantation after 1 year. All untreated control defects displayed a fibrous repair tissue. The mechanical properties represented by the e-modulus were inconsistent in the course of the study.
  
  
  CONCLUSIONS
  The implantation of a cell-free collagen type-I gel can lead to a high-quality repair tissue in the Goettinger minipig that equals a cell-based procedure after 1 year postoperatively. This study demonstrates the high chondrogenic potential of the applied collagen gel, which might help to overcome the disadvantages inherent in conventional cartilage tissue engineering methods.
authors.affiliation: Arthro Nova Clinic, Wiesserstr. 103, 83707, Ringsee, Tegernsee, Germany. uschneider@arthronovaclinic.de
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schneider
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt-Rohlfing
authors.forename: Karsten
authors.initials: K
authors.lastname: Gavenis
authors.forename: Uwe
authors.initials: U
authors.lastname: Maus
authors.forename: Ralf
authors.initials: R
authors.lastname: Mueller-Rath
authors.forename: Stefan
authors.initials: S
authors.lastname: Andereya
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000293:injuries / Q000601:surgery*; D002465:Cell Movement; D019902:Chondrocytes / Q000637:transplantation*; D024042:Collagen Type I / Q000627:therapeutic use*; D004195:Disease Models, Animal; D005782:Gels; D007718:Knee Injuries / Q000601:surgery*; D008297:Male; D013552:Swine; D013556:Swine, Miniature; D016474:Weight-Bearing
chemical_list: D024042:Collagen Type I; D005782:Gels