Clinical Biomechanics Flashcards

Which joint primarily allows inversion and eversion of the foot?

Answer: Subtalar joint

The subtalar joint, located between the talus and calcaneus bones in the foot, is primarily responsible for the complex movements of inversion and eversion. Inversion involves turning the sole of the foot inward, while eversion turns it outward. These movements are crucial for adapting the foot to uneven surfaces and maintaining balance during walking and running.

During gait, what is the primary role of the tibialis posterior muscle?

Answer: Arch stabilization and inversion

The tibialis posterior muscle is a deep posterior compartment muscle of the leg, crucial for foot stability. Its primary roles include inverting the foot and assisting in plantarflexion. Most importantly, it provides dynamic support to the medial longitudinal arch, preventing excessive pronation and maintaining the foot's structural integrity during weight-bearing activities like gait.

Which phase of gait is most associated with maximum ankle dorsiflexion?

Answer: Midstance

During the midstance phase of gait, the body's center of gravity passes directly over the supporting foot. As the tibia continues to advance forward over the stationary foot, the ankle joint reaches its maximum degree of dorsiflexion. This allows for smooth forward progression and prepares the foot for the subsequent push-off phase.

What motion occurs at the first ray during propulsion?

Answer: Plantarflexion

During the propulsion phase of gait, as the heel lifts and the body pushes off, the first ray (comprising the first metatarsal and medial cuneiform) undergoes plantarflexion. This motion, along with hallux dorsiflexion, helps to 'lock' the midfoot and create a rigid lever. This rigidity is essential for efficient transfer of force and powerful push-off from the ground.

Which foot deformity is characterized by hindfoot valgus and forefoot abduction?

Answer: Adult-acquired flatfoot

Adult-acquired flatfoot, often linked to posterior tibial tendon dysfunction, is characterized by a progressive collapse of the medial longitudinal arch. This collapse leads to a distinctive combination of hindfoot valgus (eversion) and forefoot abduction (splaying outwards). These specific deformities are key diagnostic features distinguishing it from other foot conditions.

Which muscle is primarily responsible for dorsiflexion during the swing phase of gait?

Answer: Tibialis anterior

The tibialis anterior is the primary muscle responsible for dorsiflexion of the foot. During the swing phase of gait, it contracts concentrically to lift the foot, preventing the toes from dragging on the ground. It also plays a crucial role in eccentrically controlling the foot's descent during initial contact.

Which condition results from overpronation leading to tension on the plantar fascia?

Answer: Plantar fasciitis

Overpronation, or excessive flattening of the foot's arch, significantly increases tensile stress on the plantar fascia. This thick band of tissue on the sole of the foot becomes strained and inflamed, particularly at its attachment to the heel bone. This repetitive microtrauma and inflammation are the hallmark of plantar fasciitis, causing characteristic heel pain.

Which of the following best describes the windlass mechanism?

Answer: Tension of plantar fascia during hallux dorsiflexion

The windlass mechanism describes how dorsiflexion of the great toe (hallux) during the propulsive phase of gait tightens the plantar fascia. This tightening elevates the medial longitudinal arch, effectively converting the foot into a rigid lever. This rigid lever is crucial for efficient push-off and propulsion, optimizing biomechanical efficiency.

What is the most likely biomechanical cause of a hallux limitus?

Answer: First ray dorsiflexion restriction

Hallux limitus is a condition characterized by restricted dorsiflexion at the first metatarsophalangeal (MTP) joint. This limitation often stems from a biomechanical restriction in the first ray's ability to plantarflex, which is necessary for proper hallux dorsiflexion during gait. This functional or structural limitation leads to pain and altered foot mechanics.