The performance of resurfacing implants for focal cartilage defects depends on the degenerative condition of the opposing cartilage.
BACKGROUND
Non-degradable resurfacing implants are being developed for treatment of focal cartilage defects. Performance of these implants has been investigated opposing intact cartilage. This study investigates whether implants would perform equally well when the opposing cartilage is fibrillated.


METHODS
Human osteochondral strips (~2x1x1 cm) with a smooth (n = 9) or fibrillated (n = 17) cartilage surface were obtained from human tibial plateaus excised during total knee arthroscopy. A custom-made pin-on-plate sliding indenter was used to apply simultaneous compression (0.75-3 MPa) and movement (4 mm/s over 6 mm). Either metal implants, polycarbonate-urethane or healthy porcine osteochondral plugs with a diameter of 6 mm were used as indenter.


FINDINGS
Cartilage roughness of the osteochondral strips was significantly higher for the fibrillated than the smooth group prior to sliding-indentation. Roughness of the indenters was not significantly altered by sliding indentation using either smooth or fibrillated cartilage. For all but one sample, sliding of smooth cartilage against any of the indenter surfaces did not cause damage. However, samples with fibrillated cartilage showed varied responses from seemingly unaffected to severe tissue wear as quantified by analysis of Indian ink staining and histology.


INTERPRETATION
This study demonstrates that the opposing cartilage quality is relevant for the clinical success of implanting an artificial implant in a focal cartilage defect. Therefore it is essential to test the efficacy of newly developed implants against arthritic joint surfaces, and care should be taken when interpreting in vivo studies in which implants are inserted in healthy joints.
['Damen|A H A|AHA|', 'Nickien|M|M|', 'Ito|K|K|', 'van Donkelaar|C C|CC|']
D000818:Animals D002358:Cartilage, Articular D008670:Metals D019736:Prostheses and Implants D013552:Swine D013977:Tibia
Resurfacing implant Metal Wear Cartilage mechanics Osteoarthritis Polymer