Confirmation bias affects user perception of knee braces

Area of Science:

• Orthopedics
• Biomechanical Engineering
• Human Factors Engineering

Background:

• Technological advancements in orthopedic devices aim to enhance function but can increase complexity and cost.
• Accurate assessment of orthopedic device effectiveness is crucial, especially with complex technologies.
• Confirmation bias, where users perceive outcomes aligning with expectations, may influence self-reported effectiveness.

Purpose of the Study:

• To investigate the presence and impact of confirmation bias in healthy adults using knee braces.
• To determine if user expectations influence perceived performance of orthopedic devices.

Main Methods:

• Eighteen healthy young adults participated in the study.
• Participants wore two identical knee braces, one cosmetically modified and presented as a prototype computerized brace with dynamic stiffness adjustment.
• Participants' preferences and experiences were assessed before and after walking trials.

Main Results:

• A majority of participants expressed a preference for the "computerized" brace before use.
• Objective walking analysis revealed no significant performance differences between the two braces.
• Participants maintained their preference for the "computerized" brace after the walking trials, indicating confirmation bias.

Conclusions:

• Confirmation bias significantly influences self-reported outcomes in orthopedic device studies.
• The study highlights the critical need for blinding procedures when relying on subjective user feedback.
• Placebo effects should be carefully considered when evaluating and comparing orthopedic devices.