In vivo assessment of local effects after application of bone screws delivering bisphosphonates into a compromised cancellous bone site

Abstract

Background: The primary stability of cancellous screw is difficult to obtain in bone of compromised quality and failure of screw fixation is common. To overcome this problem, it is proposed to locally deliver bisphosphonate from the screw. An in vivo validation of the increase in fixation of the cancellous screw is then needed in compromised bone. Methods: In this study, we used an overdrilling procedure, which enables consistent modeling of reduced screw stability comparable to compromised cancellous bone. Forty eight adult NZW rabbits were used in this study and all animals underwent bilateral femur implantation. One leg was implanted with the screw containing the bisphosphonate (biocoated group) while the other was used as control (control group) with the screw only. Mechanical testing and micro-CT imaging were used to assess the effect of local drug delivery of Zoledronate on screws fixation at 5 time points. Findings: At the early time points (1, 5, and 10 days), no significant difference could be seen between the biocoated and control groups. At 6 weeks, the bone volume fraction was significantly higher in the trabecular region of the biocoated group. However, this increase did not have a significant effect on the pull-out force. At the last time point, 11 weeks, both the bone volume fraction and the pull-out force were significantly higher in the biocoated group. Interpretation: The results of this study suggest that, in compromised bone, local delivery of bisphosphonate enhances the stability of bone screws.

Biomimetic Hydroxyapatite Coated Titanium Screws Demonstrate Rapid Implant Stabilization and Safe Removal <i>In-Vivo</i>

“…Sennerby et al [43] support this view noting that bone around the implant was mature after 6 weeks as indicated by histology and biomechanical testing. Bone formation around-and adjacent to-the screw implant thread at this time point was also clearly observed by Rhoshan-Ghias et al [44].…”

Does locally delivered Zoledronate influence peri-implant bone formation? – Spatio-temporal monitoring of bone remodeling in vivo

“…Local application is of particular interest in cases where existing bone needs to be preserved and augmented whilst avoiding the known side effects related to systemic administration [14,15]. Several in vivo studies have shown that a local delivery of BPs can enhance peri-implant bone density [16,17], implant fixation [18e22], and the repair of bony defects [23,24] in animal models and humans. Furthermore BPs have been shown to preserve bone allografts [25,26] as well as bone sites affected by osteonecrosis [27].…”

Controlled Delivery of Zoledronate Improved Bone Formation Locally In Vivo

“…However, biomechanical analysis showed that the maximal pullout force of the implant was associated with BPs concentration and treatment time [30], [31].…”