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8. Foot and Ankle MCQs

Practice Set 352 of 353

This practice set contains high-yield board review questions covering key concepts in 8. Foot and Ankle. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 7021

Topic: 8. Foot and Ankle

In a child with spastic diplegic cerebral palsy, true crouch gait is typically characterized by which combination of lower extremity joint positions during stance phase?

. Hip extension, knee extension, and ankle plantarflexion
. Hip flexion, knee flexion, and ankle dorsiflexion
. Hip flexion, knee extension, and ankle equinus
. Hip extension, knee flexion, and ankle equinus
. Hip adduction, knee extension, and ankle varus

Correct Answer & Explanation

. Hip flexion, knee flexion, and ankle dorsiflexion

Explanation

True crouch gait is defined by excessive hip flexion, knee flexion, and ankle dorsiflexion (calcaneus) during the stance phase. It is often caused by over-lengthened Achilles tendons in the presence of spastic/contracted hamstrings and hip flexors.

Question 7022

Topic: 8. Foot and Ankle

The "Windlass mechanism" of the foot, which is essential for normal rigid lever biomechanics during terminal stance, is primarily activated by which of the following kinematic actions?

. Plantarflexion of the first metatarsophalangeal joint
. Dorsiflexion of the first metatarsophalangeal joint
. Inversion of the subtalar joint
. Eversion of the subtalar joint
. Contraction of the tibialis posterior muscle

Correct Answer & Explanation

. Dorsiflexion of the first metatarsophalangeal joint

Explanation

Hicks' windlass mechanism is engaged by dorsiflexion of the first metatarsophalangeal (MTP) joint during late stance. This action winds the plantar fascia around the metatarsal heads, elevating the longitudinal arch and locking the midfoot for efficient push-off.

Question 7023

Topic: 8. Foot and Ankle

A patient has a severe distal femoral valgus deformity. On a standing full-length anteroposterior radiograph, how is the Mechanical Axis Deviation (MAD) accurately defined?

. The angle between the anatomical axes of the femur and tibia
. The distance from the center of the knee joint to the mechanical axis line drawn from the center of the femoral head to the center of the ankle
. The angle between the joint line and the mechanical axis of the femur
. The ratio of the medial to lateral compartment joint space
. The angle subtended by the anatomical and mechanical axes of the femur

Correct Answer & Explanation

. The distance from the center of the knee joint to the mechanical axis line drawn from the center of the femoral head to the center of the ankle

Explanation

Mechanical Axis Deviation (MAD) is measured in millimeters as the perpendicular distance from the center of the knee joint to the mechanical axis line (connecting the center of the femoral head to the center of the ankle talus).

Question 7024

Topic: 8. Foot and Ankle

During tibial lengthening over an intramedullary nail (LON) for limb length discrepancy, a patient develops insidious onset of clawing of the great toe and decreased sensation in the first web space. What is the most appropriate initial management step?

. Prescribe oral antibiotics for suspected pin tract infection
. Increase the rate of daily lengthening to accelerate consolidation
. Immediately halt the lengthening process and perform clinical examination
. Administer botulinum toxin to the flexor hallucis longus
. Proceed with urgent surgical release of the tarsal tunnel

Correct Answer & Explanation

. Immediately halt the lengthening process and perform clinical examination

Explanation

The patient is presenting with signs of deep peroneal nerve stretch injury, a known complication of aggressive tibial lengthening. The most appropriate initial step is to halt the lengthening process; occasionally, backing up the distractor may be required to relieve tension on the nerve.

Question 7025

Topic: 8. Foot and Ankle

A patient presents with a severe varus deformity of the lower extremity. Mechanical Axis Deviation (MAD) is measured on a standing long-leg alignment radiograph. How is the MAD correctly defined?

. The perpendicular distance from the center of the knee joint to the mechanical axis line.
. The angle between the mechanical and anatomic axes of the femur.
. The sum of the mechanical lateral distal femoral angle and the medial proximal tibial angle.
. The distance from the center of the femoral head to the center of the ankle talar dome.
. The intersection point of the proximal and distal anatomic joint lines.

Correct Answer & Explanation

. The perpendicular distance from the center of the knee joint to the mechanical axis line.

Explanation

Mechanical Axis Deviation (MAD) is defined as the perpendicular distance from the center of the knee joint to the mechanical axis of the lower extremity. In a normally aligned limb, the mechanical axis passes slightly medial to or through the exact center of the knee.

Question 7026

Topic: 8. Foot and Ankle

During the mid-stance phase of normal gait, where does the Ground Reaction Force (GRF) vector typically pass in the sagittal plane relative to the hip, knee, and ankle joint centers?

. Posterior to the hip, posterior to the knee, anterior to the ankle.
. Posterior to the hip, anterior to the knee, anterior to the ankle.
. Anterior to the hip, anterior to the knee, posterior to the ankle.
. Posterior to the hip, anterior to the knee, posterior to the ankle.
. Anterior to the hip, posterior to the knee, anterior to the ankle.

Correct Answer & Explanation

. Posterior to the hip, anterior to the knee, anterior to the ankle.

Explanation

At mid-stance, the GRF vector passes posterior to the hip (creating an extension moment), anterior to the knee (creating an extension moment), and anterior to the ankle (creating a dorsiflexion moment).

Question 7027

Topic: 8. Foot and Ankle

The 'Windlass mechanism' is critical for arch support during normal gait. Which phase of the gait cycle relies most heavily on this mechanism, and which anatomical structure is primarily responsible for its effect?

. Initial contact; Tibialis anterior tendon.
. Mid-stance; Posterior tibial tendon.
. Terminal stance to pre-swing; Plantar fascia.
. Loading response; Achilles tendon.
. Initial swing; Extensor hallucis longus.

Correct Answer & Explanation

. Terminal stance to pre-swing; Plantar fascia.

Explanation

The Windlass mechanism occurs during terminal stance and pre-swing when the metatarsophalangeal joints dorsiflex. This winds the plantar fascia around the metatarsal heads, elevating and stabilizing the longitudinal arch for push-off.

Question 7028

Topic: 8. Foot and Ankle

A patient with an absent tibialis anterior muscle will exhibit a specific gait abnormality during the initial contact to loading response phase. Which of the following best describes this compensatory gait pattern?

. Foot slap
. High steppage gait
. Vaulting
. Circumduction
. Genu recurvatum

Correct Answer & Explanation

. Foot slap

Explanation

The tibialis anterior typically acts eccentrically from initial contact to loading response to gently lower the foot to the ground. Absence of this eccentric control results in a 'foot slap'.

Question 7029

Topic: 8. Foot and Ankle

A 45-year-old male demonstrates a high steppage gait, characterized by excessive hip and knee flexion during the swing phase. This kinematic deviation is primarily an obligatory compensation for which underlying deficit?

. Weakness of the hip extensors
. Weakness of the ankle plantarflexors
. Weakness of the ankle dorsiflexors
. Spasticity of the quadriceps
. Contracture of the Achilles tendon

Correct Answer & Explanation

. Weakness of the ankle dorsiflexors

Explanation

A high steppage gait is a compensation for weak ankle dorsiflexors (foot drop). The patient excessively flexes the hip and knee to clear the plantarflexed foot off the ground during swing phase.

Question 7030

Topic: 8. Foot and Ankle

A patient presents with a "high steppage" gait, characterized by excessive hip and knee flexion during the swing phase. This kinematic adaptation is most commonly a compensatory mechanism for which underlying muscular deficit?

. Weakness of the hip flexors (iliopsoas)
. Weakness of the ankle plantarflexors (gastrocnemius-soleus)
. Weakness of the ankle dorsiflexors (tibialis anterior)
. Spasticity of the quadriceps femoris
. Fixed contracture of the Achilles tendon

Correct Answer & Explanation

. Weakness of the ankle dorsiflexors (tibialis anterior)

Explanation

A high steppage gait compensates for a drop foot, which is caused by weakness or paralysis of the ankle dorsiflexors. To prevent the toes from dragging on the ground during the swing phase, the patient excessively flexes the hip and knee.

Question 7031

Topic: 8. Foot and Ankle

A 12-year-old child undergoes a supramalleolar derotational osteotomy of the tibia for severe internal tibial torsion. If the fibula is left intact and not osteotomized, what is the most likely biomechanical complication at the ankle?

. Iatrogenic varus deformity of the ankle
. Iatrogenic valgus deformity of the ankle
. Development of a fixed equinus contracture
. Anterior subluxation of the talus
. Nonunion of the tibial osteotomy

Correct Answer & Explanation

. Iatrogenic valgus deformity of the ankle

Explanation

Performing a distal tibial derotational osteotomy without addressing the fibula tethers the lateral side of the mortise. Externally rotating the distal tibia against an intact fibula pulls the lateral malleolus proximally, inducing an iatrogenic valgus tilt of the ankle joint.

Question 7032

Topic: 8. Foot and Ankle

The "windlass mechanism" of the foot provides necessary rigidity to the longitudinal arch for effective push-off. Which specific kinematic action primarily engages this mechanism during terminal stance?

. Dorsiflexion of the ankle joint
. Plantarflexion of the first metatarsophalangeal (MTP) joint
. Dorsiflexion of the first metatarsophalangeal (MTP) joint
. Inversion of the subtalar joint
. Eversion of the hindfoot

Correct Answer & Explanation

. Dorsiflexion of the first metatarsophalangeal (MTP) joint

Explanation

The windlass mechanism is activated by dorsiflexion of the first MTP joint during heel rise. This motion winds the plantar fascia around the metatarsal head, drawing the calcaneus toward the forefoot, elevating the medial arch, and creating a rigid lever for push-off.

Question 7033

Topic: 8. Foot and Ankle

The anatomical axis of rotation of the talocrural (ankle) joint passes through the tips of the medial and lateral malleoli. Relative to the true mechanical and coronal planes of the tibia, how is this axis generally oriented?

. Internally rotated and laterally tilted downward
. Externally rotated and medially tilted downward
. Internally rotated and medially tilted downward
. Externally rotated and laterally tilted downward
. Strictly orthogonal in all planes

Correct Answer & Explanation

. Externally rotated and laterally tilted downward

Explanation

Because the lateral malleolus is positioned more posterior and distal than the medial malleolus, the true axis of the ankle joint is externally rotated (roughly 15 to 20 degrees) in the transverse plane and tilted laterally/downward in the coronal plane.

Question 7034

Topic: 8. Foot and Ankle



When evaluating a long standing radiograph for mechanical axis deviation (MAD), the mechanical axis line is drawn from the center of the femoral head to the center of the ankle mortise. In a patient with an uncompensated severe varus deformity of the lower extremity, where does the mechanical axis pass relative to the knee joint?

. Through the center of the knee joint
. Medial to the center of the knee joint
. Lateral to the center of the knee joint
. Anterior to the center of the knee joint
. Posterior to the center of the knee joint

Correct Answer & Explanation

. Medial to the center of the knee joint

Explanation

The normal lower extremity mechanical axis passes slightly medial to the center of the knee joint (approximately 8 mm). In a severe varus deformity, the weight-bearing axis shifts further medially, placing increased stress on the medial compartment.

Question 7035

Topic: 8. Foot and Ankle

The "windlass mechanism" is critical for the biomechanics of the foot during the terminal stance phase of gait. Which of the following kinematic actions directly engages this mechanism?

. Ankle dorsiflexion
. Subtalar eversion
. First metatarsophalangeal joint extension
. Midfoot supination
. Plantarflexion of the first ray

Correct Answer & Explanation

. First metatarsophalangeal joint extension

Explanation

The windlass mechanism stabilizes the arch of the foot to create a rigid lever for push-off. Extension of the first metatarsophalangeal (MTP) joint tightly winds the plantar fascia around the metatarsal head, elevating the longitudinal arch.

Question 7036

Topic: 8. Foot and Ankle

In an isolated ankle arthrodesis, which specific functional event (rocker mechanism) of the gait cycle is permanently lost, and how does the body immediately compensate?

. First rocker (heel rocker); compensated by early knee flexion.
. Second rocker (ankle rocker); compensated by early heel rise during mid-stance.
. Third rocker (forefoot rocker); compensated by delayed toe-off.
. First rocker (heel rocker); compensated by hyper-extension of the knee.
. Second rocker (ankle rocker); compensated by prolonged ground contact of the heel.

Correct Answer & Explanation

. Second rocker (ankle rocker); compensated by early heel rise during mid-stance.

Explanation

An ankle arthrodesis eliminates the tibiotalar motion required for the second rocker (the tibia rolling forward over the fixed foot). Patients compensate by lifting the heel early during mid-stance, transferring the pivot point to the forefoot prematurely.

Question 7037

Topic: 8. Foot and Ankle

During the normal human gait cycle, in terminal stance (immediately prior to initial contact of the contralateral foot), what is the position of the ground reaction force (GRF) vector relative to the hip, knee, and ankle joints?

. Anterior to the hip, posterior to the knee, posterior to the ankle
. Posterior to the hip, anterior to the knee, anterior to the ankle
. Posterior to the hip, posterior to the knee, anterior to the ankle
. Anterior to the hip, anterior to the knee, posterior to the ankle
. Posterior to the hip, anterior to the knee, posterior to the ankle

Correct Answer & Explanation

. Posterior to the hip, anterior to the knee, anterior to the ankle

Explanation

In terminal stance, the body advances over the stance limb, placing the GRF vector posterior to the hip (promoting extension), anterior to the knee (promoting extension), and anterior to the ankle (promoting dorsiflexion, which the calf muscles must resist).

Question 7038

Topic: 8. Foot and Ankle

According to Saunders' determinants of gait, normal pelvic drop (approximately 4 to 5 degrees) on the swing side during midstance serves which of the following primary energy-conserving functions?

. Minimizing the upward vertical displacement of the body's center of gravity
. Minimizing the downward vertical displacement of the body's center of gravity
. Reducing the lateral excursion of the center of gravity
. Decreasing the necessary angle of ankle dorsiflexion
. Increasing the stride length passively

Correct Answer & Explanation

. Minimizing the upward vertical displacement of the body's center of gravity

Explanation

Pelvic drop (a slight normal Trendelenburg) lowers the apex of the sinusoidal curve of the center of gravity during the midstance phase. This minimizes the upward vertical displacement, reducing the overall energy expenditure of gait.

Question 7039

Topic: 8. Foot and Ankle

A patient presents with a high-stepping gait, exhibiting foot slap immediately following initial contact. Electromyography is most likely to show denervation in a muscle innervated by which of the following nerves?

. Superficial peroneal nerve
. Tibial nerve
. Deep peroneal nerve
. Femoral nerve

Correct Answer & Explanation

. Deep peroneal nerve

Explanation

The patient has a steppage gait due to foot drop, which results from weakness of the ankle dorsiflexors (primarily the tibialis anterior). This muscle is innervated by the deep peroneal nerve.

Question 7040

Topic: 8. Foot and Ankle

In the sagittal plane analysis of normal gait, the 'second rocker' mechanism refers to the advancement of the tibia over the stationary foot. This corresponds to which phase of the gait cycle?

. Initial contact
. Mid-stance
. Terminal stance
. Pre-swing

Correct Answer & Explanation

. Mid-stance

Explanation

The second rocker (ankle rocker) occurs during mid-stance as the tibia rolls forward over the talus. The first rocker is the heel rocker at initial contact, and the third is the forefoot rocker at terminal stance.

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