Knee ligament injuries involving ACL account for between 100,000 and 200,000 cases per year in the US, according to a recent study published in 2020 by Harvard University. 75% of sprains occur during non-contact trauma in sports activities requiring pivotal movements such as ball sports, sliding, combat or gymnastics. The sprain occurs during a sudden deceleration associated with a change of direction that unbalances the knee or with the landing of a jump followed by a release of the knee in valgus. This brutal movement is due to a tilt of the foot in pronation which causes the knee to spiral into a valgus-internal tibial rotation, “the medial collapse” of the knee.

This mechanism is the cause of most tears in the anterior cruciate ligament of the knee. However, the starting point of this sudden tilt of the foot in pronation is a characteristic of FHL that we have highlighted by the analysis of the footprint on the ground during our walking reports on a connected treadmill. Today, for a population at high risk of recurrence, we recommend combining FHL tenolysis with ACL reconstruction to improve the prognosis of the knee. A retrospective study of more than 120 cases is underway to assess the medium-term results of this association.