Kinematic quantitation of the patellar tendon reflex using a tri-axial accelerometer

Area of Science:

• Biomechanics
• Neurology
• Medical Instrumentation

Background:

• The patellar tendon reflex is a fundamental neurological response.
• Accurate and accessible methods for quantifying this reflex are crucial for clinical assessment.
• Existing methods can be complex or restrictive.

Purpose of the Study:

• To develop a simple, portable, and non-constraining procedure for quantifying the patellar tendon reflex.
• To utilize knee joint angular speed, derived from acceleration data, as the primary measurement metric.
• To establish the reliability and validity of this novel method compared to existing techniques.

Main Methods:

• A customized tendon hammer applied tapping force to the patellar tendon.
• A tri-axial accelerometer placed at the ankle joint measured acceleration.
• Knee joint angular speed was calculated from acceleration data using a signal analyzer and notebook PC.
• Data from healthy and spastic individuals were collected and analyzed.

Main Results:

• The procedure demonstrated consistent time delay and acceleration time across participants.
• Peak tapping force and peak angular speed showed a strong exponential relationship.
• Spastic individuals exhibited significantly higher mean asymptotic peak angular speed (160°/s) compared to healthy individuals (72°/s).

Conclusions:

• The developed method offers a portable and user-friendly approach to quantifying the patellar tendon reflex.
• This technique effectively differentiates reflex responses between healthy and spastic populations.
• The findings support the clinical utility of this simple, non-constraining reflex measurement system.