Bilayer Implants: Electromechanical Assessment of Regenerated Articular Cartilage in a Sheep Model.
OBJECTIVE
To compare the regenerative capacity of 2 distinct bilayer implants for the restoration of osteochondral defects in a preliminary sheep model.


METHODS
Critical sized osteochondral defects were treated with a novel biomimetic poly-ε-caprolactone (PCL) implant (Treatment No. 2; n = 6) or a combination of Chondro-Gide and Orthoss (Treatment No. 1; n = 6). At 19 months postoperation, repair tissue (n = 5 each) was analyzed for histology and biochemistry. Electromechanical mappings (Arthro-BST) were performed ex vivo.


RESULTS
Histological scores, electromechanical quantitative parameter values, dsDNA and sGAG contents measured at the repair sites were statistically lower than those obtained from the contralateral surfaces. Electromechanical mappings and higher dsDNA and sGAG/weight levels indicated better regeneration for Treatment No. 1. However, these differences were not significant. For both treatments, Arthro-BST revealed early signs of degeneration of the cartilage surrounding the repair site. The International Cartilage Repair Society II histological scores of the repair tissue were significantly higher for Treatment No. 1 (10.3 ± 0.38 SE) compared to Treatment No. 2 (8.7 ± 0.45 SE). The parameters cell morphology and vascularization scored highest whereas tidemark formation scored the lowest.


CONCLUSIONS
There was cell infiltration and regeneration of bone and cartilage. However, repair was incomplete and fibrocartilaginous. There were no significant differences in the quality of regeneration between the treatments except in some histological scoring categories. The results from Arthro-BST measurements were comparable to traditional invasive/destructive methods of measuring quality of cartilage repair.
University Medical Center Schleswig-Holstein Campus Lübeck, Clinic for Orthopedics and Trauma Surgery, Lübeck, Germany; Mayo Clinic, Orthopedic Surgery, Rochester, MN, USA.
Jan C
JC
Schagemann
University Medical Center Schleswig-Holstein Campus Lübeck, Clinic for Orthopedics and Trauma Surgery, Lübeck, Germany.
Nicola
N
Rudert
Mayo Clinic, Orthopedic Surgery, Rochester, MN, USA.
Michelle E
ME
Taylor
Biomedical and Chemical Engineering, Polytechnique Montreal, Montreal, Canada; Biomomentum Inc., Laval, Quebec, Canada.
Sotcheadt
S
Sim
Biomomentum Inc., Laval, Quebec, Canada.
Eric
E
Quenneville
Biomomentum Inc., Laval, Quebec, Canada.
Martin
M
Garon
University of Lübeck, Institute of Anatomy, Lübeck, Germany.
Mathias
M
Klinger
Biomedical and Chemical Engineering, Polytechnique Montreal, Montreal, Canada.
Michael D
MD
Buschmann
University Medical Center Schleswig-Holstein Campus Lübeck, Clinic for Orthopedics and Trauma Surgery, Lübeck, Germany.
Hagen
H
Mittelstaedt
Arthro-BST; bilayer implant; cartilage repair; electromechanics; poly-ε-caprolactone
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