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8. Foot and Ankle MCQs

Practice Set 311 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 6201

Topic: 8. Foot and Ankle

The 'high arch' in a cavus foot is often exacerbated by a contracture of which plantar structure?

. Long plantar ligament.
. Spring ligament.
. Plantar fascia.
. Deltoid ligament.
. Fibular collateral ligament.

Correct Answer & Explanation

. Plantar fascia.

Explanation

The plantar fascia is a strong aponeurosis on the sole of the foot that plays a crucial role in maintaining the longitudinal arch. In a cavus foot, the arch is pathologically elevated, leading to a tightening and contracture of the plantar fascia. This contracture contributes to the rigidity of the high arch and is a common source of pain (plantar fasciitis) at its calcaneal insertion. Releasing the plantar fascia is often a component of surgical correction for flexible or semi-rigid cavus feet.

Question 6202

Topic: 8. Foot and Ankle

Which specific muscle weakness is a primary driver of the 'stork leg' appearance in patients with Charcot-Marie-Tooth disease and cavus foot?

. Gastrocnemius and soleus.
. Tibialis anterior and posterior.
. Peroneal muscles (longus and brevis).
. Flexor digitorum longus and brevis.
. Intrinsic foot muscles.

Correct Answer & Explanation

. Peroneal muscles (longus and brevis).

Explanation

The 'stork leg' appearance (or 'inverted champagne bottle' calves) in Charcot-Marie-Tooth disease is due to significant atrophy and weakness of the peroneal muscles (peroneus longus and brevis) as well as other distal lower extremity muscles. The preserved bulk of the thigh muscles contrasting with the wasted calf muscles creates this characteristic appearance, which is a hallmark of distal hereditary neuropathies causing cavus foot.

Question 6203

Topic: 8. Foot and Ankle

When obtaining radiographs for a suspected cavus foot, which views are considered essential for comprehensive assessment?

. Anterior-posterior and lateral views of the ankle.
. Weight-bearing anterior-posterior, lateral, and oblique views of the foot.
. Skyline view of the patella and lateral view of the knee.
. Stress radiographs of the ankle to assess ligamentous laxity.
. Non-weight-bearing anterior-posterior and lateral views of the foot.

Correct Answer & Explanation

. Weight-bearing anterior-posterior, lateral, and oblique views of the foot.

Explanation

For a comprehensive assessment of foot deformities like cavus foot, weight-bearing radiographs are essential. They allow visualization of the bony relationships under physiological loading conditions. The standard views include weight-bearing anterior-posterior (AP), lateral, and oblique views of the foot. These views allow for measurements of angles like Meary's angle, calcaneal pitch, and talonavicular coverage, all of which are critical for characterizing the deformity. Non-weight-bearing views can mask the true extent of the deformity.

Question 6204

Topic: 8. Foot and Ankle

Which of the following is an expected finding on a lateral weight-bearing radiograph of a typical cavus foot?

. Increased talar declination angle.
. Reduced calcaneal pitch angle.
. Dorsal apex angulation of the talo-first metatarsal angle (Meary's angle).
. Lateral displacement of the navicular on the talar head.
. Decreased forefoot abduction.

Correct Answer & Explanation

. Dorsal apex angulation of the talo-first metatarsal angle (Meary's angle).

Explanation

In a cavus foot, the talo-first metatarsal angle (Meary's angle) on a lateral weight-bearing radiograph typically shows a dorsal apex angulation (a 'break' in the straight line) due to the plantarflexed first metatarsal or forefoot equinus. The normal alignment is a straight line or slight plantarflexion of the first metatarsal relative to the talus. An increased calcaneal pitch angle (more vertical calcaneus) and a reduced talar declination angle (more vertical talus) are also characteristic, but the dorsal apex angulation of Meary's angle is a very direct indicator of the midfoot/forefoot 'cavus' component.

Question 6205

Topic: 8. Foot and Ankle
What is the clinical significance of a positive Silfverskiöld test in a patient with a cavus foot and associated ankle equinus?
. It indicates tightness of the tibialis posterior muscle.
. It suggests a fixed osseous block to dorsiflexion.
. It differentiates between isolated gastrocnemius tightness and combined gastrocnemius-soleus tightness.
. It confirms a plantarflexed first ray deformity.
. It is a test for subtalar joint instability.

Correct Answer & Explanation

. It differentiates between isolated gastrocnemius tightness and combined gastrocnemius-soleus tightness.

Explanation

The Silfverskiöld test is used to differentiate between isolated gastrocnemius tightness and combined gastrocnemius-soleus (Achilles) tightness. With the knee extended, the ankle is dorsiflexed. If dorsiflexion is limited, the test is repeated with the knee flexed. If ankle dorsiflexion improves with knee flexion, it indicates isolated gastrocnemius tightness (as the gastrocnemius crosses the knee joint). If dorsiflexion remains limited with the knee flexed, it indicates combined gastrocnemius-soleus tightness, meaning the soleus (which does not cross the knee) is also tight. This distinction guides surgical planning for Achilles tendon lengthening.

Question 6206

Topic: 8. Foot and Ankle

A 'cavus index' has been proposed as a quantitative measure. Which of the following parameters would most likely be included in such an index?

. Ankle-brachial index.
. Talo-first metatarsal angle and calcaneal pitch angle.
. Forefoot abduction-adduction angle.
. Range of motion of the knee joint.
. Tibial torsion angle.

Correct Answer & Explanation

. Talo-first metatarsal angle and calcaneal pitch angle.

Explanation

A cavus index aims to quantify the severity of the cavus deformity. Key radiographic angles that characterize a cavus foot are the talo-first metatarsal angle (Meary's angle), which indicates forefoot equinus or midfoot sag, and the calcaneal pitch angle, which reflects the hindfoot arch. These angles are directly altered in a cavus foot and are therefore crucial parameters for any quantitative assessment of the deformity. The other options are either unrelated or less central to the primary definition of cavus foot.

Question 6207

Topic: 8. Foot and Ankle

Which of the following is the most common cause of a progressive, bilateral cavus foot in adults?

. Traumatic injury to the foot.
. Idiopathic etiology.
. Diabetic neuropathy.
. Charcot-Marie-Tooth disease.
. Spinal cord tumor.

Correct Answer & Explanation

. Charcot-Marie-Tooth disease.

Explanation

Charcot-Marie-Tooth (CMT) disease is the most common hereditary neuropathy and is a leading cause of progressive, bilateral cavus foot, often presenting in childhood or adolescence but continuing to progress into adulthood. While idiopathic causes are also common, CMT is a specific and frequently diagnosed underlying neurological reason. Diabetic neuropathy can cause foot deformities (including cavus, though more often Charcot arthropathy or flatfoot), but CMT is more classically associated with cavus foot development. Spinal cord tumors are less common and often unilateral/asymmetric. Trauma is usually unilateral.

Question 6208

Topic: 8. Foot and Ankle

In a patient presenting with a cavus foot and a history of recurrent ankle sprains, what specific ligamentous complex is most commonly affected due to the altered biomechanics?

. Deltoid ligament complex.
. Anterior inferior tibiofibular ligament.
. Spring ligament.
. Lateral collateral ligament complex of the ankle.
. Interosseous ligament of the subtalar joint.

Correct Answer & Explanation

. Lateral collateral ligament complex of the ankle.

Explanation

Patients with cavovarus feet have a hindfoot varus alignment. This places the ankle in a position of chronic inversion and increases the load on the lateral side of the ankle joint. This anatomical predisposition significantly increases the risk of recurrent inversion ankle sprains, primarily affecting the lateral collateral ligament complex (anterior talofibular ligament, calcaneofibular ligament). Correcting the hindfoot varus is crucial for addressing this instability.

Question 6209

Topic: 8. Foot and Ankle

Which of the following surgical strategies for a flexible cavovarus foot with a flexible plantarflexed first ray aims to rebalance the deforming forces without performing an osteotomy?

. Dwyer calcaneal osteotomy.
. Dorsal closing wedge osteotomy of the first metatarsal.
. Plantar fascia release and peroneus longus to brevis tendon transfer.
. Triple arthrodesis.
. Talonavicular fusion.

Correct Answer & Explanation

. Plantar fascia release and peroneus longus to brevis tendon transfer.

Explanation

For a flexible cavovarus foot with a flexible plantarflexed first ray, a common soft tissue strategy involves a plantar fascia release and a peroneus longus to brevis tendon transfer. The plantar fascia release addresses the contracture. The peroneus longus typically overpowers the tibialis anterior, plantarflexing the first ray. Transferring the peroneus longus (or a portion of it) to the peroneus brevis tendon reduces its plantarflexion force on the first ray and increases dorsiflexion, helping to rebalance the foot. This can correct the forefoot equinus and secondary hindfoot varus without requiring bony osteotomies, especially in younger patients or milder deformities.

Question 6210

Topic: 8. Foot and Ankle

What is the primary concern when considering aggressive surgical correction of a cavus foot in a patient with significant sensory neuropathy (e.g., severe Charcot-Marie-Tooth)?

. Risk of nerve damage during surgery.
. Difficulty with hardware removal post-operatively.
. Increased risk of non-union or delayed union.
. High incidence of cosmetic dissatisfaction.
. Compromised wound healing and risk of neuropathic ulceration post-operatively.

Correct Answer & Explanation

. Compromised wound healing and risk of neuropathic ulceration post-operatively.

Explanation

Patients with significant sensory neuropathy (as seen in advanced Charcot-Marie-Tooth or diabetic neuropathy) have impaired protective sensation. Aggressive surgical correction, especially with fusions or extensive osteotomies, can lead to increased stress on skin and soft tissues, particularly if the correction is not precisely plantigrade. This, combined with poor sensation, significantly increases the risk of impaired wound healing, infection, and devastating neuropathic ulcerations (Charcot foot-like changes) post-operatively, which can be difficult to manage. Therefore, surgical planning must be meticulous, and less aggressive or staged approaches may be preferred.

Question 6211

Topic: 8. Foot and Ankle

The aetiology of idiopathic cavus foot is often considered to be a 'forme fruste' of which underlying condition?

. Rheumatoid arthritis.
. Spinal dysraphism.
. Cerebral palsy.
. Charcot-Marie-Tooth disease.
. Post-traumatic deformity.

Correct Answer & Explanation

. Charcot-Marie-Tooth disease.

Explanation

The term 'forme fruste' refers to an atypical or mild form of a disease. Many cases of 'idiopathic' cavus foot, especially those that are bilateral and slowly progressive, are now considered to be very mild or subclinical forms of Charcot-Marie-Tooth (CMT) disease, where the neurological deficits are so subtle they are not clinically obvious without specialized testing (like nerve conduction studies). This hypothesis suggests a significant genetic predisposition underlying many ostensibly 'idiopathic' cases.

Question 6212

Topic: 8. Foot and Ankle
When examining the range of motion of the ankle in a cavus foot, limited dorsiflexion is often observed. This limitation, if flexible, can be attributed to tightness of which muscle group?
. Tibialis anterior.
. Peroneal muscles.
. Gastrocnemius-soleus complex.
. Intrinsic foot muscles.
. Flexor hallucis longus.

Correct Answer & Explanation

. Gastrocnemius-soleus complex.

Explanation

Tightness of the gastrocnemius-soleus complex (Achilles tendon) is a very common finding in cavus feet, leading to limited ankle dorsiflexion, which is termed 'ankle equinus.' This tightness contributes to the overall deformity and can exacerbate other foot issues. Assessment using the Silfverskiöld test helps determine if the tightness is purely gastrocnemius or involves the soleus as well, guiding potential surgical lengthening.

Question 6213

Topic: 8. Foot and Ankle

Which of the following is an early sign of intrinsic muscle weakness in the foot, often observed in patients developing a cavus deformity?

. Flattening of the longitudinal arch.
. Development of a hallux valgus deformity.
. Clawing of the lesser toes.
. Increased ankle dorsiflexion.
. Pain localized to the cuboid bone.

Correct Answer & Explanation

. Clawing of the lesser toes.

Explanation

Weakness of the intrinsic foot muscles (lumbricals, interossei) is a hallmark of many neurological conditions causing cavus foot (e.g., CMT). This weakness leads to an imbalance where the strong extrinsic flexors and extensors overpower the intrinsic muscles. This results in the characteristic claw toe deformity (hyperextension of the MTP joint and flexion of the PIP/DIP joints) and is often one of the earliest discernible signs in the development of a cavus foot.

Question 6214

Topic: 8. Foot and Ankle

During your examination of a rigid cavovarus foot, you perform a 'supination test' by attempting to passively supinate the midfoot. What is this test primarily assessing?

. Flexibility of the ankle joint.
. Integrity of the tibialis posterior tendon.
. Forefoot flexibility and fixed forefoot pronation.
. Midfoot rigidity and fixed forefoot valgus.
. Rigidity of the subtalar joint.

Correct Answer & Explanation

. Forefoot flexibility and fixed forefoot pronation.

Explanation

The 'supination test' (or 'reverse Coleman block test') assesses for fixed forefoot valgus, which is a rare but distinct deformity that can drive hindfoot varus. If a fixed forefoot valgus is present, the forefoot cannot be fully supinated (inverted) to correct the hindfoot. However, the question asks about a 'supination test' in arigid cavovarusfoot, and attempting to supinate the midfoot usually assesses the rigidity of the midfoot and hindfoot complex, differentiating between flexible and rigid components. A 'fixed forefoot valgus' would manifest as an inability to passively supinate the forefoot to align with the hindfoot. In the context ofcavovarus, fixed forefoot valgus is not the typical driver. A 'fixed forefoot pronation' is also not correct. More broadly, attempting to supinate a cavovarus foot tests how much of the deformity is flexible and reducible vs. fixed and rigid, particularly in the midfoot and hindfoot.

Question 6215

Topic: 8. Foot and Ankle

When planning surgical correction for a severe cavovarus foot, what is the most significant concern regarding correction of the calcaneal pitch angle?

. Overcorrection can lead to a flatfoot deformity.
. Insufficient correction can result in continued pain.
. Overcorrection can cause anterior ankle impingement.
. Insufficient correction can lead to metatarsalgia.
. Difficulty in achieving a precise correction without fluoroscopy.

Correct Answer & Explanation

. Overcorrection can cause anterior ankle impingement.

Explanation

In a severe cavus foot, the calcaneal pitch angle is significantly increased (the calcaneus is more vertically oriented). Aggressive correction that excessively dorsiflexes the calcaneus (e.g., by flattening the arch too much or performing an osteotomy that over-dorsiflexes the hindfoot) can lead to anterior ankle impingement. This occurs as the anterior process of the calcaneus or talus impinges against the tibia, limiting ankle dorsiflexion and causing pain. The goal is to restore a physiological calcaneal pitch, not to over-correct it to a flatfoot or impinging position.

Question 6216

Topic: 8. Foot and Ankle

A cavus foot with an apex in the midfoot, leading to a 'rocker bottom' deformity but with a high arch, is best described as a:

. Calcaneocavus foot.
. Forefoot equinus cavus foot.
. Fixed plantarflexed first ray cavus foot.
. Midfoot break cavus foot (e.g., a 'tarsal cavus').
. Compensatory cavovarus foot.

Correct Answer & Explanation

. Midfoot break cavus foot (e.g., a 'tarsal cavus').

Explanation

A cavus foot where the apex of the deformity is in the midfoot, rather than a generalized high arch, is often described as a 'midfoot break cavus' or 'tarsal cavus.' This type can sometimes lead to a pseudo-rocker bottom appearance in severe cases due to the severe plantarflexion of the midfoot relative to the hindfoot and forefoot. Calcaneocavus specifically refers to a dorsiflexed calcaneus, while forefoot equinus or plantarflexed first ray relates to the forefoot and usually results in a more uniform high arch without a distinct 'break' in the midfoot.

Question 6217

Topic: 8. Foot and Ankle

When assessing the strength of the tibialis posterior muscle in a patient with a cavus foot, which action should you ask the patient to perform against resistance?

. Ankle dorsiflexion and eversion.
. Ankle plantarflexion and inversion.
. Toe extension and abduction.
. Ankle dorsiflexion and inversion.
. Ankle plantarflexion and eversion.

Correct Answer & Explanation

. Ankle plantarflexion and inversion.

Explanation

The tibialis posterior muscle is a primary invertor and plantarflexor of the foot. To test its strength, the patient should be asked to perform combined ankle plantarflexion and inversion against resistance. Weakness of the tibialis posterior can contribute to pes planus (flatfoot) rather than cavus, but its strength is important to assess in the overall foot balance.

Question 6218

Topic: 8. Foot and Ankle

What is the common age of presentation for Charcot-Marie-Tooth (CMT) disease, which is a frequent cause of cavus foot?

. Infancy (0-2 years).
. Early childhood (2-5 years).
. Late childhood to adolescence (5-15 years).
. Early adulthood (20-30 years).
. Late adulthood (60+ years).

Correct Answer & Explanation

. Late childhood to adolescence (5-15 years).

Explanation

Charcot-Marie-Tooth (CMT) disease, particularly CMT1, typically presents in late childhood or adolescence, often between 5 and 15 years of age. Symptoms like clumsiness, frequent ankle sprains, difficulty with balance, and the development of cavus feet and claw toes usually become apparent during these years as the peripheral neuropathy progresses. While it is a lifelong progressive condition, the initial clinical presentation is often in this age range.

Question 6219

Topic: 8. Foot and Ankle

Which specific deformity involving the great toe is commonly seen in conjunction with a cavus foot?

. Hallux rigidus.
. Hallux valgus.
. Hallux varus.
. Hallux interphalangeus.
. Hallux extensus (dorsiflexed MTP joint, flexed IP joint).

Correct Answer & Explanation

. Hallux extensus (dorsiflexed MTP joint, flexed IP joint).

Explanation

In a cavus foot, the great toe often develops a 'claw hallux' or 'hallux extensus' deformity. This involves hyperextension at the first metatarsophalangeal (MTP) joint and flexion at the interphalangeal (IP) joint. This is similar to the clawing of the lesser toes, resulting from an imbalance between strong extrinsic flexors/extensors and weak intrinsic muscles, combined with a plantarflexed first metatarsal causing a 'buckling' effect. Hallux valgus and rigidus are distinct deformities, though hallux valgus can sometimes occur in cavus feet due to other factors.

Question 6220

Topic: 8. Foot and Ankle

When examining a patient with a suspected cavus foot, you observe significant callosities under the heads of the first and fifth metatarsals and along the lateral border of the foot. This pattern of callosity suggests:

. A flexible flatfoot deformity.
. A well-distributed weight-bearing pattern.
. Increased pressure on the medial column due to valgus hindfoot.
. An abnormally high arch with concentrated pressure at the forefoot pillars and lateral hindfoot.
. Early signs of Charcot neuroarthropathy.

Correct Answer & Explanation

. An abnormally high arch with concentrated pressure at the forefoot pillars and lateral hindfoot.

Explanation

Callosities are formed in areas of high pressure. In a cavus foot, the abnormally high arch means that the midfoot does not bear weight efficiently. Consequently, weight-bearing is concentrated on the 'tripod' of the foot: the heel, the first metatarsal head, and the fifth metatarsal head, along with the lateral border of the foot (due to hindfoot varus). Callosities in these areas are a classic clinical sign of a cavus foot deformity, indicating concentrated pressure and altered biomechanics.

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