Effect of foot orthotics on running kinetics in adults with anterior cruciate ligament reconstruction: A controlled laboratory study.

After ACL reconstruction, people with pronated feet often show altered landing forces during running, patterns linked in prior research to reinjury risk and later joint problems. This study asked whether foot orthotics could immediately change those forces, and whether the answer depended on how far someone was into recovery, testing men at 6, 12, and 18 months post-surgery against healthy controls under four footwear conditions including a plain shoe, a placebo insert, a double-density orthotic, and an arch-support orthotic. Compared with healthy controls, the surgical groups at 12 and 18 months showed higher impact forces and faster loading rates, and rotational forces around the foot were elevated at 6 and 18 months, suggesting abnormal loading persists well beyond initial recovery.

The double-density orthotic reduced that excess rotational force compared with a plain shoe, and other orthotic effects varied by recovery stage. This is a single small laboratory trial capturing only immediate effects, so whether these changes translate into real injury protection over time remains unknown.

If you've had ACL reconstruction and also have flatter, pronated feet, your running pattern may still be different from someone without a knee injury, even well over a year later. This study looked at men recovering from ACL surgery at three different points, 6, 12, and 18 months out, comparing them to healthy men, and tested how their feet hit the ground while running in four types of shoe inserts. The researchers found that at 12 and 18 months, the surgical group's feet hit the ground harder and faster than the healthy group's, and twisting forces around the foot were also elevated at certain points.

One type of insert, a double-density design, reduced some of that excess twisting force right away compared to a plain shoe, though effects differed depending on how far along someone was in recovery. This was a small, one-time lab test, so it only tells us about immediate changes during that single running session, not whether wearing these inserts long-term would actually lower injury risk or improve outcomes over months or years.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This controlled laboratory trial compared ground reaction forces during running across three ACL reconstruction with pronated feet groups (6, 12, and 18 months post-operative, n=15 each) and matched healthy controls (n=15), under four randomised footwear conditions: control shoe, placebo orthotic, double-density orthotic, and arch-support orthotic. Relative to controls, the 12- and 18-month groups showed significantly higher impact vertical peaks and vertical loading rates, while peak positive free moment was elevated at 6 and 18 months, and the 6-month group had a longer time-to-peak for impact force. A significant main effect of orthotic type emerged for free moment, with the double-density orthotic reducing it relative to control shoe.

Significant group-by-orthotic interactions for peak posterior force, loading rate, and stance time indicate that orthotic effects were stage-dependent rather than uniform. These are acute, single-session biomechanical outcomes in a small sample (n=45 across surgical groups), not injury or clinical outcomes, and causal inference about long-term benefit is not supported. The findings indicate persistent kinetic abnormalities up to 18 months post-surgery and stage-specific orthotic responses, but longitudinal data are needed to establish clinical relevance.