Toe-Off Phase of Gait: Joint Mechanics and Clinical Relevance

Toe-Off Phase Overview

The toe-off phase occurs at the very end of the stance phase of the gait cycle, representing a transition from stance to swing. This phase, also referred to as pre-swing or propulsion, involves the full plantar flexion of the ankle, dorsiflexion of the rear-foot and digits (toes) and plantar flexion of the forefoot, and the engagement of the Windlass Mechanism, which elevates the all the arches of the foot. The Windlass Mechanism, named by Hicks in 1954, tightens the plantar fascia through dorsiflexion of the metatarsophalangeal (MTP) joints, transforming the foot into a rigid lever. This is crucial for efficient propulsion during walking and running (Bolivar et al., 2013).

Foot and Ankle Mechanics

Sagittal Plane:

In the sagittal plane, the ankle moves from dorsiflexion in loading phase to plantarflexion as the heel rises off the ground. This transition is driven by the concentric contraction of the gastrocnemius and soleus muscles, which generate the force necessary to propel the body forward (Kim et al., 2011). During toe-off, the metatarsophalangeal (MTP) joints undergo plantar flexion as the rear-foot dorsiflexes, which, in turn, activates the Windlass Mechanism (Bolivar et al., 2013). The tightening of the plantar fascia elevates the medial arch and transforms the foot into a rigid structure for efficient push-off.

Frontal Plane:

In the frontal plane, the foot undergoes a shift from a pronated position during midstance into supinated during toe-off. This transition is aided by the subtalar joint, which moves into inversion. Supination elevates the medial arch, ensuring that the foot becomes a stable lever capable of handling the forces generated during propulsion (Whittle, 2014). The tibialis posterior muscle plays a crucial role in preventing overpronation and facilitating a smooth transition into supination.

Transverse Plane:

In the transverse plane, the rear foot undergoes external rotation during toe-off. This movement helps align the forefoot and rearfoot for efficient propulsion. The coordinated actions of rear foot external rotation, internal rotation of the forefoot and supination are essential for the effective engagement of the Windlass Mechanism, ensuring that the body moves forward efficiently while minimizing energy expenditure (Perry, 1992).

Talocrural (ankle) Joint Mechanics

Talocrural joint motion is defined as the motion of the talus relative to the tibia

The talocrural (ankle) joint moves from plantar flexed into a dorsiflexed during toe-off. This movement is driven by the gastrocnemius and soleus muscles, which contract concentrically to push the foot off the ground. The talocrural joint acts as a hinge, allowing for efficient transfer of force through the leg during propulsion (Perry, 1992). If dorsiflexion is impaired, as in the case of Achilles tendinopathy, propulsion is significantly affected, leading to inefficiencies in the gait cycle.

Sagittal Plane:

During toe-off, the talocrural joint (ankle joint) moves from dorsiflexion into plantarflexion. This transition is essential for generating the force needed for forward propulsion also knee extension, hip extension and posterior tilt of the pelvis.

Frontal Plane:

Minimal movement occurs in the frontal plane at the talocrural joint during toe-off. However, slight inversion may occur as the foot moves toward supination via the subtalor joint, particularly as the foot begins to push off in preparation for the swing phase. This inversion is primarily managed by the tibialis posterior and the peroneal muscles again via the subtalor joint.

Transverse Plane:

In the transverse plane, the talocrural joint experiences some degree of external rotation during toe-off from the motion of the subtalar joint. This motion is critical in aligning the foot for efficient propulsion. The external rotation occurs in response to the shifting forces during gait, allowing the foot to transition smoothly into supination.

Subtalar Joint (rear-foot) Mechanics

Subtalar joint motion is defined as motion of the calcaneus relative to the talus

The subtalar joint moves from a pronated position during midstance transitioning into supination during toe-off. Supination stiffens the foot and elevates the arches of the foot, creating the necessary rigidity for efficient push-off. The subtalar joint’s ability to control this inversion is crucial for proper force distribution and reducing the risk of overpronation (Whittle, 2014).

Sagittal Plane:

In the sagittal plane, the subtalar joint dorsiflexes from loading phase into a plantar flexed position into supination at toe-off.

Frontal Plane:

The subtalar joint experiences inversion during toe-off, which contributes to the transition from pronation an eversion motion to supination an inversion motion. This inversion increases the all the arches of the foot but the medial arch height of the foot is most visible, making the foot more rigid and allowing for effective push-off. The tibialis posterior plays a vital role in controlling this inversion.

Transverse Plane:

In the transverse plane, the subtalar joint undergoes external rotation from an internal rotation as loading phase, in tandem with the foot’s movement toward supination. This external rotation ensures proper alignment and force distribution across the rearfoot as the body moves forward. This alignment is critical for energy-efficient propulsion and avoiding injury.