Functional Hallux Limitus or Functional Hallux Rigidus is defined by the impossibility of extending the MTP1 (metatarsophalangeal) during the course of the step when walking. In the propulsive phase when the ankle is placed in dorsiflexion position, the MTP1 remains stiff and cannot be placed in dorsiflexion. This biomechanical condition is the consequence of a blockage (tenodesis effect) of the flexor hallucis longus tendon at the level of the hindfoot which prevents this tendon from sliding freely.

From a biomechanical point of view, this dysfunction has significant repercussions, in particular on the stability of the foot.

Functional Hallux Limitus or Functional Hallux Rigidus is a relatively common but little-known condition because it is not very symptomatic locally and is difficult to diagnose. Little is known about the tests to demonstrate the blockage of the tendon sliding of the hallucis longus flexor, as are the tests to assess the mobility of the subtalar joint.

The functional disorders caused by functional hallux rigidus are not confined to the foot but also affect the knee, hip and lumbopelvic region. The disruption of the normal course of the step leads to joint overloads and distance compensation mechanisms.

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