Dynamic Knee Valgus: Are We Fixing the Right Problem? | Find Your Stride | Edinburgh Podiatrist

Dynamic Knee Valgus: Are We Fixing the Right Problem?

Dynamic knee valgus (DKV)—the knee moving inwards during landing or cutting—is often treated as something that needs to be “corrected”. But does reducing valgus actually make an athlete safer? A recent randomised controlled trial compared two established injury-prevention programmes, Stop-X and Knee Control, in 45 male professional futsal players with DKV. After eight weeks, both programmes reduced knee valgus during a maximal side-cut.

Interestingly, however, the athletes also produced more force against the ground and loaded that force more quickly. So, did their movement become safer? We don’t know—and that is the most important finding to take from this study.

This x-ray shows a valgus knee position. 'Dynamic knee valgus' is seen when the knee moves inward (into the position shown above) during landing or cutting.

What did the study find?

Players completed Stop-X, Knee Control or their normal training for eight weeks.

Both intervention groups reduced measured knee valgus by approximately 5–6°, while the control group showed almost no change. Neither programme was clearly superior.

But alongside reduced valgus, both training groups demonstrated substantial increases in peak vertical ground-reaction force and loading rate.

At first glance, more force might sound undesirable in an injury-prevention programme. But more force does not automatically mean greater injury risk. Athletes need to produce and absorb large forces to sprint, jump, brake and change direction. Increased force following a programme containing strength and plyometric training could simply indicate that these players became more capable of producing force. The more relevant question is whether they could control that force effectively.

Less valgus ≠ fewer ACL injuries

This is where interpretation needs caution. The researchers measured biomechanics—not ACL injuries. Reducing a movement characteristic associated with ACL injury mechanisms does not prove that injury risk has fallen. ACL injuries are multifactorial and influenced by joint position, rotation, muscle function, trunk control, fatigue, sporting situations and many other factors. There is another important limitation: DKV was measured using 2D video.

This is practical and clinically accessible, but knee valgus is a three-dimensional movement involving the hip, knee, tibia, ankle and foot. A smaller 2D angle cannot tell us exactly what happened to loading within the knee.

Approach speed and cutting angle were also self-selected. If players performed the post-training test faster or more aggressively, this could partly explain the increased forces.

So we should be careful about concluding that the programmes either reduced injury risk or increased potentially harmful loading. Neither has been demonstrated.

Why should podiatrists care?

DKV is not simply a knee problem. Movement during cutting results from interaction between the foot, ankle, knee, hip and trunk. The foot provides the interface with the ground, while ankle mobility, plantar-flexor capacity, lower-limb strength and whole-body movement strategy can all influence how forces are managed. For podiatrists assessing an athlete with apparent knee valgus, the aim therefore shouldn’t simply be to make the knee look straighter.

Assessment should consider foot and ankle function, strength, mobility, footwear, fatigue and the athlete’s overall ability to produce and control force during their sport.

What about runners?

The direct relevance to distance running is limited. These were male futsal players performing maximal side-cuts. But there is a useful broader lesson for running biomechanics: Lower forces aren’t automatically better. Running performance requires athletes to repeatedly produce, absorb and redirect force. Rather than trying to minimise loading at all costs, rehabilitation and training should develop the athlete’s capacity to tolerate and control the forces their sport requires.

The clinical takeaway

Stop-X and Knee Control both changed biomechanics: knee valgus decreased while ground-reaction force and loading rate increased. Whether those changes actually reduce ACL injuries remains unanswered. Perhaps the most useful finding is that neither programme was clearly superior. Both contain familiar ingredients: strength, plyometrics, balance, trunk control and progressive landing/change-of-direction exercises. For clinicians, the focus should therefore be less on finding the perfect branded programme and more on developing the athlete’s overall physical capacity and movement control.

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Citation

Rouhi, F., Shamsi Majelan, A., & Jafarnezhadgero, A. A. (2025). Comparison of Stop-X and Knee Control training on side cut kinetics in futsal players with dynamic knee valgus: A randomized controlled trial. Scientific Reports, 15, 40314. https://doi.org/10.1038/s41598-025-24003-w