A novel device for standardizing marker placement at the calcaneus.

Area of Science:

• Biomechanics
• Orthopedics
• Kinetics

Background:

• Accurate anatomical reference frames are crucial for 3D multisegment foot modeling.
• Palpating anatomical landmarks for marker placement can be difficult or impossible.
• A novel Calcaneal Marker Device (CMD) was developed to standardize calcaneal marker placement.

Purpose of the Study:

• To evaluate the reliability of calcaneal marker placement using the CMD compared to manual techniques.
• To quantify the impact of marker placement variability on intersegment angle calculations in foot biomechanics.

Main Methods:

• A randomized repeated-measures design was employed.
• Calcaneal marker placement repeatability was assessed for manual technique and CMD.
• Translational changes and clinical effects on intersegment angles were quantified.

Main Results:

• The CMD significantly reduced intraobserver and interobserver variability in marker placement (e.g., interobserver variability <1.3 mm with CMD vs. 5.8 mm manually).
• Variability in computed intersegment angles was lower with the CMD (0.4°–4.0°) compared to manual placement (1.0°–8.7°).
• Intraobserver variability was consistently lower with the CMD across different therapists.

Conclusions:

• The Calcaneal Marker Device substantially reduces marker placement variations in 3D foot modeling.
• The CMD enhances the reliability of anatomical reference frames for rearfoot motion analysis.
• This standardization may approach the limits imposed by therapist skill and tissue artifacts.