Reliability testing of the heel marker in three-dimensional gait analysis

Area of Science:

• Biomechanics
• Gait Analysis
• Orthopedics

Background:

• Accurate anatomical axis definition in 3D gait analysis relies heavily on precise marker placement.
• The Oxford Foot Model (OFM) hindfoot axes are particularly sensitive to posterior heel marker placement.
• Improving the reliability of this marker placement is crucial for multi-segment foot models.

Purpose of the Study:

• To evaluate the effectiveness of two novel 3D-printed jigs (ratio caliper and heel mould) in improving the reliability of hindfoot marker placement for the OFM.
• To compare the reliability of these jigs against traditional eyeball marker placement.
• To assess intra-tester and inter-tester variability in hindfoot angle calculations.

Main Methods:

• Two 3D-printed jigs, a ratio caliper and a heel mould, were designed and tested.
• Kinematic data using the Oxford Foot Model were collected from ten healthy adults.
• Marker placement repeatability was assessed by experienced and inexperienced gait analysts for five clinically relevant variables.

Main Results:

• The ratio caliper demonstrated the lowest intra-tester variability for both experienced (all 5 variables) and inexperienced (4/5 variables) analysts.
• Inter-tester variability showed the ratio caliper was not consistently superior to eyeball placement (2/5 variables).
• The heel mould yielded the poorest results, especially for hindfoot rotation, indicating it is the least reliable method.

Conclusions:

• The ratio caliper shows potential for enhancing intra-tester reliability in hindfoot marker placement.
• The ratio caliper did not consistently improve inter-tester reliability compared to eyeball placement.
• The use of a heel mould for hindfoot marker placement is not recommended due to its high variability.