Does a counterforce brace reduce common extensor tendon loading during a wrist extension task? An in vivo study.

Area of Science:

• Biomechanics
• Musculoskeletal Ultrasound

Background:

• The common extensor origin (CEO) tendon at the elbow is susceptible to overuse injuries.
• Counterforce braces are commonly used to manage elbow pain, but their biomechanical effects on tendon properties are not fully understood.

Purpose of the Study:

• To assess the biomechanical effect of a counterforce brace on the common extensor origin (CEO) tendon's stiffness.
• To investigate if brace pressure influences shear wave velocity (SWV), a proxy for tendon stiffness, during varying levels of wrist extensor contraction.

Main Methods:

• A cross-sectional study involving 19 healthy participants.
• Ultrasound elastography was used to measure shear wave velocity (SWV) of the CEO tendon.
• Participants performed wrist and finger extension at 0%, 20%, 30%, and 40% of maximum voluntary contraction (MVC) with and without an 80 mmHg counterforce brace.

Main Results:

• The counterforce brace showed no significant effect on CEO tendon SWV at rest or during any tested MVC level (0-40%).
• A significant increase in SWV was observed as wrist extension MVC levels increased (p=0.048).
• This indicates that tendon stiffness increases with muscle contraction intensity.

Conclusions:

• The applied counterforce brace does not appear to alter the biomechanical properties (tendon stiffness) of the common extensor origin tendon.
• Tendon stiffness, measured by SWV, increases with greater wrist extensor muscle activation.
• Further research may be needed to explore brace efficacy under different conditions or for specific pathologies.