title: Porous tantalum biocomposites for osteochondral defect repair: A follow-up study in a sheep model.
abstract: OBJECTIVE
  We sought to determine if a durable bilayer implant composed of trabecular metal with autologous periosteum on top would be suitable to reconstitute large osteochondral defects. This design would allow for secure implant fixation, subsequent integration and remodeling.
  
  
  METHODS
  Adult sheep were randomly assigned to one of three groups (n = 8/group): 1. trabecular metal/periosteal graft (TMPG), 2. trabecular metal (TM), 3. empty defect (ED). Cartilage and bone healing were assessed macroscopically, biochemically (type II collagen, sulfated glycosaminoglycan (sGAG) and double-stranded DNA (dsDNA) content) and histologically.
  
  
  RESULTS
  At 16 weeks post-operatively, histological scores amongst treatment groups were not statistically different (TMPG: overall 12.7, cartilage 8.6, bone 4.1; TM: overall 14.2, cartilage 9.5, bone 4.9; ED: overall 13.6, cartilage 9.1, bone 4.5). Metal scaffolds were incorporated into the surrounding bone, both in TM and TMPG. The sGAG yield was lower in the neo-cartilage regions compared with the articular cartilage (AC) controls (TMPG 20.8/AC 39.5, TM 25.6/AC 33.3, ED 32.2/AC 40.2 µg sGAG/1 mg respectively), with statistical significance being achieved for the TMPG group (p < 0.05). Hypercellularity of the neo-cartilage was found in TM and ED, as the dsDNA content was significantly higher (p < 0.05) compared with contralateral AC controls (TM 126.7/AC 71.1, ED 99.3/AC 62.8 ng dsDNA/1 mg). The highest type II collagen content was found in neo-cartilage after TM compared with TMPG and ED (TM 60%/TMPG 40%/ED 39%). Inter-treatment differences were not significant.
  
  
  CONCLUSIONS
  TM is a highly suitable material for the reconstitution of osseous defects. TM enables excellent bony ingrowth and fast integration. However, combined with autologous periosteum, such a biocomposite failed to promote satisfactory neo-cartilage formation.Cite this article: E. H. Mrosek, H-W. Chung, J. S. Fitzsimmons, S. W. O'Driscoll, G. G. Reinholz, J. C. Schagemann. Porous tantalum biocomposites for osteochondral defect repair: A follow-up study in a sheep model. Bone Joint J 2016;5:403-411. DOI: 10.1302/2046-3758.59.BJR-2016-0070.R1.
authors.affiliation: Specialist "Biologic Joint Reconstruction", Department for Trauma-, Hand- and Reconstructive Surgery, Ortenau Klinikum Offenburg, Ebertplatz 12, 77654 Offenburg, Germany and Cartilage and Connective Tissue Research Laboratory, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: E H
authors.initials: EH
authors.lastname: Mrosek
authors.affiliation: Cartilage and Connective Tissue Research Laboratory, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: H-W
authors.initials: HW
authors.lastname: Chung
authors.affiliation: Cartilage and Connective Tissue Research Laboratory, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Fitzsimmons
authors.affiliation: Cartilage and Connective Tissue Research Laboratory, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA odriscoll.shawn@mayo.edu@mayo.edu.
authors.forename: S W
authors.initials: SW
authors.lastname: O'Driscoll
authors.affiliation: Cartilage and Connective Tissue Research Laboratory, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: G G
authors.initials: GG
authors.lastname: Reinholz
authors.affiliation: Cartilage Specialist, Clinic for Orthopedics and Trauma Surgery, University Medical Center Schleswig-Holstein Campus Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany and Cartilage and Connective Tissue Research Laboratory, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Schagemann
keywords: Cartilage engineering; Neocartilage; Osteochondral defects; Scaffolds; Tantalum; Trabecular metal; sheep