title: Cartilage damage caused by metal implants applied for the treatment of established localized cartilage defects in a rabbit model.
abstract: The purpose of the current study was to investigate the feasibility of the application of defect-size femoral implants in a rabbit model of established cartilage defects and compare this treatment to microfracturing. In 31 New Zealand White rabbits, a medial femoral condyle defect was created in each knee. After 4 weeks, 3 animals were killed for defect baseline values. In the other 28 rabbits, knees were sham-operated, treated with microfracturing, or treated by placing an oxidized zirconium (OxZr) or cobalt-chromium (CoCr) implant (theta articulating surface 3.5 mm; fixating pin of 9.1 mm length). These animals were sacrificed 4 weeks after treatment. Joints were evaluated macroscopically. Implant osseointegration was measured by automated histomorphometry, and cartilage repair was scored microscopically. Cartilage quality was analyzed macroscopically and microscopically. Bone-implant contact was 63.2% +/- 3.2% for CoCr and 62.5% +/- 3.2% for OxZr. Cartilage defects did not show complete healing, nor during subsequent sham-surgery or microfracturing. For all treatments, considerable cartilage damage in the articulating medial tibia, and degeneration of lateral tibial and femoral cartilage was observed (p < 0.05). Both CoCr and OxZr implant-treated defects showed an increase of cartilage degeneration compared to microfracturing and sham-operated defects (p < 0.05). Although only a single short-term follow-up period was investigated in this study, caution is warranted using small metal implants as a treatment for established localized cartilage defects because, even after 4 weeks in this model, the metal implants caused considerable degeneration of the articulating surface.
authors.affiliation: Department of Orthopaedics, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Roel J H
authors.initials: RJ
authors.lastname: Custers
authors.forename: Laura B
authors.initials: LB
authors.lastname: Creemers
authors.forename: Mattie H P
authors.initials: MH
authors.lastname: van Rijen
authors.forename: Ab J
authors.initials: AJ
authors.lastname: Verbout
authors.forename: Daniel B F
authors.initials: DB
authors.lastname: Saris
authors.forename: Wouter J A
authors.initials: WJ
authors.lastname: Dhert
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000473:pathology*; D002857:Chromium / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry; D005260:Female; D005264:Femoral Fractures / Q000473:pathology / Q000628:therapy; D017102:Fracture Healing; D016348:Osseointegration; D019736:Prostheses and Implants; D011817:Rabbits; D013978:Tibial Fractures / Q000473:pathology / Q000628:therapy; D013997:Time Factors; D015040:Zirconium / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002857:Chromium; D003035:Cobalt; D015040:Zirconium