Functional Brace in ACL Surgery: Force Quantification in an In Vivo Study.

Area of Science:

• Biomechanics
• Orthopedic Engineering
• Sports Medicine

Background:

• A functional anterior cruciate ligament (ACL) brace is needed to dynamically support the knee joint.
• Current braces lack angle-dependent force matching for native ACL function, especially post-surgery.

Purpose of the Study:

• Quantify posteriorly directed external forces on the tibia from static and dynamic ACL braces.
• Hypothesize that static brace forces remain constant, unlike dynamic brace forces, across knee flexion angles.

Main Methods:

• Controlled laboratory study with seven healthy adult males.
• Participants performed unloaded extension, sit-to-stand, and stair ascent with static and dynamic ACL braces.
• Kinematic data and tibial forces were collected using motion capture and pressure mapping.

Main Results:

• Dynamic ACL brace applied significantly larger posterior tibial forces (80.2 N at 30° flexion) than static brace (10.1 N).
• These differences were consistent across tested functional activities and force settings (P < .001).

Conclusions:

• Dynamic ACL braces provide greater tibial support in extension, mimicking in vivo ACL forces.
• Further research is needed to confirm if this brace reduces knee laxity and improves patient outcomes.
• Dynamically restraining the tibia may enhance pre- and postoperative ACL treatment.