Vibration Testing Procedures for Bone Stiffness Assessment in Fractures Treated with External Fixation

Area of Science:

• Biomedical Engineering
• Orthopedics
• Medical Imaging

Background:

• Accurate bone healing assessment is vital for fracture treatment and external fixator management.
• Current clinical methods (bone manipulation, X-rays) are qualitative and limited in frequency.
• Quantitative methods are needed for objective and repeatable fracture healing evaluation.

Purpose of the Study:

• To develop and validate a quantitative frequency response analysis (FRA) procedure for assessing bone healing in fractures treated with external fixators.
• To overcome soft-tissue damping effects by using fixator pins for bone excitation and response measurement.
• To characterize the mechanical properties of treated bone non-invasively.

Main Methods:

• Developed and validated a test procedure using frequency response analysis (FRA) on tibia phantoms.
• Compared different excitation techniques and input-output combinations, focusing on impact tests with a micro-hammer.
• Utilized fixator pins to transmit excitation and measure response, bypassing soft-tissue interference.

Main Results:

• Demonstrated the effectiveness of an FRA procedure based on impact tests using a micro-hammer.
• Confirmed that external fixator pins and the fixator itself alter the phantom's frequency response by increasing resonant frequencies.
• Established a reliable method for characterizing bone mechanical properties via fixator pins.

Conclusions:

• The developed FRA procedure using fixator pins is effective for quantitative bone healing assessment in externally fixated fractures.
• This non-invasive technique overcomes limitations of traditional methods, offering improved monitoring capabilities.
• Future in vitro and in vivo studies will apply this procedure to monitor fracture healing progression.