Measurement of biomechanical interactions at the stump-socket interface in lower limb prostheses

Area of Science:

• Prosthetics and Biomechanics
• Gait Analysis
• Rehabilitation Engineering

Background:

• Relative movement between the stump and socket in lower limb prostheses can affect comfort and function.
• Existing methods for measuring this movement may be limited in accuracy or scope.
• Understanding stump-socket dynamics is crucial for improving prosthetic design and patient outcomes.

Purpose of the Study:

• To introduce and validate a novel motion-capturing approach for quantifying stump-socket relative movement.
• To assess the feasibility of measuring this movement during level walking at various speeds.
• To correlate stump-socket movement with applied loads during gait.

Main Methods:

• A motion-capturing system was employed to measure relative movement.
• The approach was demonstrated on a single male trans-tibial amputee using a Patella Tendon Bearing (PTB) socket.
• Measurements were taken during level walking at different velocities, analyzing two translational degrees of freedom in the sagittal plane.

Main Results:

• A linear correlation was identified between applied load and stump-socket movement in the proximodistal (pd) direction.
• In the anteroposterior (ap) direction, stump movement was significantly influenced by gait event-specific motion sequences.
• The effect of walking speed on stump-socket movement was also investigated and discussed.

Conclusions:

• The novel motion-capturing approach is feasible for measuring stump-socket relative movement in lower limb prostheses.
• Load is a significant factor influencing proximodistal movement, while gait dynamics dominate anteroposterior movement.
• Findings provide valuable insights for optimizing prosthetic socket design and improving gait performance.