The influence of soft tissue artifacts on multi-segment foot kinematics

Area of Science:

• Biomechanics
• Musculoskeletal analysis
• Medical imaging

Background:

• Marker-based motion analysis is crucial for understanding biomechanics.
• Soft tissue artifacts (STAs) can compromise the accuracy of kinematic data.
• Quantifying STAs in foot movement analysis is essential for reliable results.

Purpose of the Study:

• To quantify 3D soft tissue artifacts (STAs) for foot markers.
• To evaluate the impact of STAs on multi-segment foot kinematics using the Oxford Foot Model (OFM) and Rizzoli Foot Model (RFM).
• To identify foot marker locations most susceptible to STAs.

Main Methods:

• Fifteen subjects with asymptomatic feet underwent CT scans with markers placed on the foot.
• Loaded and unloaded CT scans were used to calculate 3D marker displacement (STA).
• Kinematic calculations were performed with and without STA correction to determine errors.

Main Results:

• Markers on the lateral malleolus and posterior calcaneus exhibited the largest STAs.
• STAs introduced clinically relevant errors in hindfoot-shank joint angles, particularly in extreme plantar flexion.
• The Rizzoli Foot Model (RFM) showed greater sagittal plane error, while the Oxford Foot Model (OFM) showed greater transverse plane error.

Conclusions:

• Soft tissue artifacts introduce significant errors in multi-segment foot kinematic analysis.
• Specific marker placements (lateral malleolus, posterior calcaneus) are prone to substantial STAs.
• Reconsideration of marker placement is advised for improving the accuracy of foot movement models.