In vitro and in vivo investigations into the biocompatibility of diamond-like carbon (DLC) coatings for orthopedic applications

Diamond-like carbon (DLC) shows great promise as a durable, wear- and corro sion-resistant coating for biomedical implants. The effects of DLC coatings on the musculoskeletal system have not been investigated in detail. In thi s study, DLC coatings were deposited on polystyrene 24-well tissue culture plates by fast-atom bombardment from a hexane precursor, Two osteoblast-lik e cell lines were cultured on uncoated and DLC-coated plates for periods of up to 72 h. The effects of DLC coatings on cellular metabolism were invest igated by measuring the production of three osteoblast-specific marker prot eins: alkaline phosphatase, osteocalcin, and type I collagen. There was no evidence that the presence of the DLC coating had any adverse effect on any of the parameters measured in this study. In a second series of experiment s, DLC-coated cobalt-chromium cylinders were implanted in intramuscular loc ations in rats and in transcortical sites in sheep. Histologic analysis of specimens retrieved 90 days after surgery showed that the DLC-coated specim ens were well tolerated in both sites. These data indicate that DLC coating s are biocompatible in vitro and in vivo, and further investigations into t heir long-term biological and tribological performance are now warranted. ( C) 2001 John Wiley & Sons, Inc.