The design and performance of an experimental external fixation device with load transducers

Area of Science:

• Biomedical Engineering
• Orthopedic Research
• Biomechanics

Background:

• Fracture healing is commonly studied using ovine tibia osteotomy models.
• External fixation devices are frequently used in these models.
• Understanding the loads on external fixators is crucial but poorly documented.

Purpose of the Study:

• To develop and validate a device for measuring axial compression and in-plane bending loads on external fixators.
• To assess the accuracy and usability of the developed measurement device in vivo.
• To provide preliminary data on loads experienced during normal walking in ovine fracture models.

Main Methods:

• Development of a unilateral external fixation device with integrated load-measuring transducers.
• Testing the device's rigidity and ease of application for in vivo measurements.
• Calibration and error estimation for compression and bending transducers.
• Preliminary in vivo data collection during normal walking in sheep.

Main Results:

• The developed device is rigid, easy to apply, and allows straightforward in vivo measurements.
• Estimated error limits for compression transducer: +37.9 N and -21.4 N.
• Estimated error limits for bending transducer: +3.6 Nm and -4.2 Nm.
• Preliminary measurements indicated maximum loads of 345 N compression and 28 Nm in-plane bending during normal walking.

Conclusions:

• The novel unilateral device accurately measures key loads in ovine tibia external fixation models.
• This tool enhances understanding of biomechanical forces during fracture healing studies.
• The findings provide valuable data for optimizing external fixation strategies in orthopedic research.