Bone reactions to controlled loading of endosseous implants: a pilot study.

Area of Science:

• Biomaterials Science
• Orthopedic Research
• Animal Models in Research

Background:

• Osseointegrated implants are crucial for bone repair and replacement.
• Understanding bone's response to mechanical loading is vital for implant success.
• A validated animal model is needed to study these complex interactions.

Purpose of the Study:

• To validate an experimental setup for applying controlled loads to bone tissue via osseointegrated implants in rabbits.
• To assess the feasibility of implant placement, maintenance, and loading within the rabbit tibia model.
• To evaluate bone response to mechanical loading using radiological and micro-computed tomography (microCT) methods.

Main Methods:

• New Zealand White rabbits underwent tibial implantation.
• Pneumatically activated device applied cyclic loads (1 Hz) to implants over 14 weeks, increasing weekly.
• Bone response was assessed using conventional radiography, computed tomography (CT), and microCT analysis of specific volumes of interest (VOIs).

Main Results:

• Osseous responses varied, including increased porosity and lamellar changes in the cortical bone.
• Inter-implant VOI showed initial volume increase, followed by stabilization and a biphasic bone density change (decrease then increase).
• Peri-implant VOI exhibited continuous bone volumetric density augmentation throughout the loading period.

Conclusions:

• The validated rabbit model allows for the study of bone's response to mechanical loading on implants.
• Cortical bone in the inter-implant region shows a two-phase response to loading, while peri-implant bone adapts through density increase.
• Future loading devices should be designed for sustained heavy cyclic loads; rabbits are suitable but inflammation requires monitoring.