Local delivery of zoledronate from a poly (d,l-lactide)-coating increases fixation of hydroxy-coated implants

Initial secure implant fixation predicts long-term survival. Bisphosphonates are anti-resorptive agents. They have been shown to increase implant fixation. We investigated whether local delivery of zoledronate from a poly-d,l-lactide (PDLLA)-coating could improve fixation and osseointegration of hydroxy-apatite coated implants. Cylindrical hydroxy-apatite coated implants were bilaterally inserted press-fit into the proximal tibiae of 10 dogs. On one side the implant was coated with PDLLA containing zoledronate. The PDLLA coating was applied upon the hydroxy-apatite coating. We used the contralateral implant as control. This implant was not coated with a poly-d,l-lactide. Observation period was 12 weeks. We evaluated implant fixation with histomorphometry and biomechanical push-out test. Zoledronate resulted in an approximately threefold increase in all biomechanical parameters when comparing data with their respective controls. We found that zoledronate increased preservation of old lamellar bone and increased formation of new woven bone. This study indicates that local delivery of zoledronate from a PDDLA coating has the potential to increase implant fixation. Studies investigating different doses of zoledronate and longer follow-up are needed.