Hamstring stretch reflex: could it be a reproducible objective measure of functional knee stability?"

Area of Science:

• Orthopedics
• Sports Medicine
• Neuromuscular Physiology

Background:

• The anterior cruciate ligament (ACL) is crucial for knee stability, preventing anterior tibial translation.
• ACL injury or reconstruction can impact neuromuscular function.
• A hamstring stretch reflex triggered by tibial translation may offer an objective measure of this function.

Purpose of the Study:

• To evaluate the reliability and consistency of the ACL-hamstring stretch reflex using the KT-2000 arthrometer.
• To determine if this reflex can be a viable clinical tool for assessing neuromuscular recovery.

Main Methods:

• Utilized the KT-2000 arthrometer to induce tibial translation in 20 participants with intact ACLs.
• Recorded electromyography of the biceps femoris muscle during testing.
• Tested a subgroup of 4 patients undergoing arthroscopy with direct ACL traction for comparison.

Main Results:

• A stretch reflex was elicited in 38.5% of 182 trials.
• Mean onset latency was 58.9 ± 17.9 ms.
• Average pull force, stretch velocity, and rate of force were recorded.

Conclusions:

• The ACL-hamstring reflex response rate is too low for reliable clinical application.
• The reflex has limited value in assessing neuromuscular function return post-ACL injury.