Bonit Coating Leads to Macroscopic Bone Ingrowth at 8 Weeks After Primary Total Hip Arthroplasty

Primary total hip arthroplasty with cementless stems has numerous advantages over cemented total hip arthroplasty in patients with good bone quality. To enhance osseointegration with ingrowth into the implant, various surface treatments have been proposed. Multiple biomechanical studies in animals have shown that bioactive coatings enhance osseointegration and increase construct stability. Bony ingrowth in humans can only be assessed in rare instances of periprosthetic femoral fractures. In this case report, we describe the findings after a periprosthetic fracture mandating stem exchange in a patient who experienced a fall 8 weeks after implantation. The retrieved proximal Bonit (DOT GmbH, Rostock, Germany) coated stem showed substantial macroscopically visible trabecular bone. This finding supports results from animal studies that showed enhanced metaphyseal bone ingrowth with Bonit coating of implants.