Menu

8. Foot and Ankle MCQs

Practice Set 222 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 4421

Topic: 8. Foot and Ankle
A 32-year-old man presents to the emergency department with severe ankle pain after an axial load injury. Radiographs show a displaced talar neck fracture with associated dislocation of both the subtalar and tibiotalar joints (Hawkins type III). What is the approximate reported rate of avascular necrosis (AVN) of the talar body associated with this specific injury pattern?
. 0 to 10%
. 20 to 30%
. 40 to 50%
. 70 to 100%
. AVN does not occur in this injury pattern

Correct Answer & Explanation

. 70 to 100%

Explanation

Talar neck fractures are classified by the Hawkins classification. A Hawkins type I is nondisplaced (AVN risk 0-10%). A type II involves displacement of the talar neck with subtalar subluxation/dislocation (AVN risk 20-50%). A type III involves displacement of the talar neck with dislocation of both the subtalar and tibiotalar joints, completely disrupting all three major sources of blood supply to the talus (the artery of the tarsal canal, deltoid branches, and dorsalis pedis branches). The rate of AVN for a Hawkins type III fracture is exceptionally high, reported between 70% and 100%.

Question 4422

Topic: 8. Foot and Ankle

A 27-year-old male is involved in a high-speed motor vehicle collision and sustains a displaced talar neck fracture with subluxation of the subtalar joint. The tibiotalar and talonavicular joints remain congruent.

He undergoes urgent open reduction and internal fixation. At 8 weeks postoperatively, plain radiographs demonstrate a subchondral radiolucent band in the dome of the talus. What is the clinical significance of this radiographic finding?

. It indicates an indolent deep infection requiring operative debridement.
. It signifies impending talar body collapse due to avascular necrosis (AVN).
. It is a highly reliable sign of intact vascularity to the talar body.
. It strongly suggests delayed union or nonunion of the talar neck fracture.
. It represents early post-traumatic cystic changes associated with osteoarthritis.

Correct Answer & Explanation

. It is a highly reliable sign of intact vascularity to the talar body.

Explanation

The radiographic finding described is Hawkins' sign, which presents as a subchondral radiolucent band in the talar dome typically visible 6 to 8 weeks post-injury. This radiolucency is the result of subchondral osteopenia secondary to disuse and active bone resorption. Because osteoclastic bone resorption requires a viable blood supply, the presence of Hawkins' sign is a highly reliable indicator that vascularity to the talar body is intact, thereby predicting a very low risk of developing avascular necrosis (AVN). The fracture described in the vignette is a Hawkins type II talar neck fracture, which generally carries a 20-50% baseline risk of AVN.

Question 4423

Topic: 8. Foot and Ankle

A 38-year-old male falls from a height of 20 feet and sustains a closed, highly comminuted intra-articular calcaneus fracture.

Surgical management with open reduction and internal fixation is planned utilizing a standard extensile lateral approach. During the surgical approach, creation of a full-thickness subperiosteal flap is critical to minimize wound healing complications. Which of the following structures is most at risk of injury and must be carefully identified and protected near the proximal aspect of the vertical limb of this incision?

. Sural nerve
. Superficial peroneal nerve
. Posterior tibial artery
. Medial calcaneal nerve
. Deep peroneal nerve

Correct Answer & Explanation

. Sural nerve

Explanation

The extensile lateral approach to the calcaneus involves an L-shaped incision, with the vertical limb placed midway between the fibula and the Achilles tendon, and the horizontal limb in line with the base of the fifth metatarsal. The sural nerve and the lesser saphenous vein run posteriorly and laterally in the ankle and are at significant risk of injury, particularly near the proximal aspect of the vertical limb and the distal extent of the horizontal limb. Creating a full-thickness subperiosteal 'no-touch' flap is essential to protect the vascular supply to the lateral skin flap (primarily from the lateral calcaneal artery) and to retract the sural nerve and peroneal tendons safely out of the surgical field.

Question 4424

Topic: 8. Foot and Ankle

A 30-year-old female presents with midfoot pain after falling from a horse. Her foot was plantarflexed at the time of impact. Radiographs demonstrate a widening of the space between the first and second metatarsal bases with a distinct "fleck sign." Based on current literature, which of the following treatments results in better functional outcomes and lower revision rates for purely ligamentous Lisfranc injuries?

. Closed reduction and non-weight-bearing casting for 8 weeks
. Open reduction and internal fixation (ORIF) with transarticular screws
. Primary partial midfoot arthrodesis (TMT 1, 2, and 3)
. Open reduction and flexible Kirschner wire fixation
. Closed reduction and percutaneous pinning

Correct Answer & Explanation

. Primary partial midfoot arthrodesis (TMT 1, 2, and 3)

Explanation

For purely ligamentous Lisfranc injuries, multiple prospective randomized studies have demonstrated that primary arthrodesis of the medial column (first, second, and third tarsometatarsal joints) yields superior functional outcomes, less pain, and lower revision hardware removal rates compared to standard ORIF. ORIF is typically preferred for bony Lisfranc fracture-dislocations.

Question 4425

Topic: 8. Foot and Ankle

A 34-year-old male falls from a height of 15 feet and sustains a displaced talar neck fracture with subluxation of the subtalar joint, while the tibiotalar and talonavicular joints remain located. According to the Hawkins classification, this is a Type II injury. The primary blood supply to the talar body, which is at highest risk in this injury, is derived from the:

. Artery of the tarsal canal
. Artery of the tarsal sinus
. Deltoid branches of the posterior tibial artery
. Dorsalis pedis artery branches
. Sural artery branches

Correct Answer & Explanation

. Artery of the tarsal canal

Explanation

The talus has a tenuous, retrograde blood supply, predisposing it to avascular necrosis following neck fractures. The primary blood supply to the vast majority of the talar body is the artery of the tarsal canal, which is a branch of the posterior tibial artery. It forms an anastomotic sling with the artery of the tarsal sinus. While deltoid branches supply the medial aspect, the artery of the tarsal canal provides the most significant vascular contribution.

Question 4426

Topic: 8. Foot and Ankle
A 30-year-old woman is involved in a high-speed motor vehicle collision and sustains a Hawkins Type III talar neck fracture. Which of the following blood vessels provides the dominant blood supply to the talar body, which is critically at risk in this injury?
. Artery of the tarsal canal
. Artery of the sinus tarsi
. Dorsalis pedis artery branches
. Deltoid branches of the posterior tibial artery
. Peroneal artery perforators

Correct Answer & Explanation

. Artery of the tarsal canal

Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, provides the dominant blood supply to the talar body. In a Hawkins Type III fracture (talar neck fracture with subtalar and tibiotalar dislocation), the three main sources of blood supply (artery of the tarsal canal, artery of the sinus tarsi, and dorsal neck vessels) are typically disrupted, leading to an exceptionally high rate of avascular necrosis (AVN), often exceeding 80%.

Question 4427

Topic: 8. Foot and Ankle

A 22-year-old collegiate football player sustains a hyperplantarflexion injury to his midfoot. Weight-bearing radiographs demonstrate 3 mm of widening between the base of the first and second metatarsals, with a subtle "fleck sign" adjacent to the medial cuneiform. What is the anatomical path of the primarily injured ligament?

. From the medial cuneiform to the base of the first metatarsal
. From the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal
. From the intermediate cuneiform to the base of the second metatarsal
. From the cuboid to the base of the fourth metatarsal
. From the navicular to the medial cuneiform

Correct Answer & Explanation

. From the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal

Explanation

The Lisfranc ligament is an interosseous ligament that connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is the critical stabilizer of the tarsometatarsal joint complex. A "fleck sign" represents an avulsion fracture of this ligament. There is no direct transverse ligament connecting the bases of the first and second metatarsals.

Question 4428

Topic: Midfoot & Hindfoot

A 24-year-old professional football player sustains an acute, purely ligamentous Lisfranc injury involving the first, second, and third tarsometatarsal joints. Which of the following surgical treatments has been shown to yield the best long-term functional outcomes for this specific injury pattern?

. Closed reduction and percutaneous pinning with Kirschner wires
. Open reduction and internal fixation with flexible suture-button constructs
. Open reduction and internal fixation with solid transarticular screws
. Primary arthrodesis of the first, second, and third tarsometatarsal joints
. Application of a circular fine-wire external fixator

Correct Answer & Explanation

. Primary arthrodesis of the first, second, and third tarsometatarsal joints

Explanation

Purely ligamentous Lisfranc injuries exhibit a higher rate of hardware failure, loss of reduction, and subsequent post-traumatic midfoot arthritis when treated with open reduction and internal fixation (ORIF) compared to primarily bony avulsion fractures. High-quality prospective studies (e.g., Ly and Coetzee) have demonstrated that primary arthrodesis of the medial column (first, second, and third tarsometatarsal joints) for purely ligamentous injuries results in superior functional outcome scores, a more reliable return to pre-injury activity levels, and significantly lower revision rates than ORIF.

Question 4429

Topic: Midfoot & Hindfoot
A 25-year-old male sustains a Hawkins Type III talar neck fracture following a fall from height. Which of the following best describes the pathoanatomy of a Hawkins Type III fracture and its associated risk of avascular necrosis (AVN)?
. Talar neck fracture with subtalar dislocation; AVN risk 20-50%
. Nondisplaced talar neck fracture; AVN risk 0-10%
. Talar neck fracture with subtalar, tibiotalar, and talonavicular dislocation; AVN risk 100%
. Talar neck fracture with subtalar dislocation; AVN risk 0-10%
. Talar neck fracture with subtalar and tibiotalar dislocation; AVN risk 80-100%

Correct Answer & Explanation

. Talar neck fracture with subtalar and tibiotalar dislocation; AVN risk 80-100%

Explanation

The Hawkins classification for talar neck fractures is prognostic for AVN. Type I: nondisplaced (0-15% AVN). Type II: subtalar dislocation (20-50% AVN). Type III: subtalar and tibiotalar dislocation, where the AVN risk approaches 80-100%. Type IV includes talonavicular dislocation.

Question 4430

Topic: 8. Foot and Ankle

A 32-year-old motorcyclist sustains a completely displaced, highly comminuted intra-articular fracture of the calcaneus (Sanders Type IV). If open reduction and internal fixation (ORIF) is attempted via an extensile lateral approach, which nerve is at greatest risk of iatrogenic injury?

. Deep peroneal nerve
. Saphenous nerve
. Sural nerve
. Posterior tibial nerve
. Medial plantar nerve

Correct Answer & Explanation

. Sural nerve

Explanation

The sural nerve courses posterior to the lateral malleolus and crosses the lateral aspect of the hindfoot. It is at significant risk of iatrogenic injury during the extensile lateral approach to the calcaneus. A 'no-touch' technique and full-thickness flap retraction are utilized to protect it.

Question 4431

Topic: 8. Foot and Ankle
A 30-year-old male falls from a height and sustains a Hawkins type III fracture of the talar neck. Which of the following blood vessels provides the primary residual blood supply to the talar body, and what is the approximate rate of avascular necrosis (AVN) for this fracture type?
. Artery of the tarsal canal; 20-30%
. Dorsalis pedis artery; 50%
. Deltoid branches of the posterior tibial artery; 80-100%
. Peroneal artery; 10-15%
. Artery of the sinus tarsi; 5-10%

Correct Answer & Explanation

. Deltoid branches of the posterior tibial artery; 80-100%

Explanation

A Hawkins type III talar neck fracture involves displacement of the neck with dislocation of both the subtalar and tibiotalar joints. This severe injury disrupts the arteries of the sinus tarsi and tarsal canal, leaving only the deltoid branches of the posterior tibial artery (supplying the medial aspect of the body) if they remain intact. Due to this catastrophic vascular insult, the rate of avascular necrosis (AVN) of the talar body approaches 80% to 100%.

Question 4432

Topic: 8. Foot and Ankle

A 22-year-old gymnast sustains a hyperplantarflexion injury to her midfoot. Weight-bearing radiographs reveal widening of the interval between the first and second metatarsal bases. In a purely ligamentous Lisfranc injury, which of the following best describes the anatomical origin and insertion of the primarily injured ligament?

. Originates on the medial cuneiform and inserts on the base of the first metatarsal
. Originates on the middle cuneiform and inserts on the base of the second metatarsal
. Originates on the lateral aspect of the medial cuneiform and inserts on the medial aspect of the base of the second metatarsal
. Originates on the medial aspect of the middle cuneiform and inserts on the lateral aspect of the base of the first metatarsal
. Originates on the navicular and inserts on the base of the second metatarsal

Correct Answer & Explanation

. Originates on the lateral aspect of the medial cuneiform and inserts on the medial aspect of the base of the second metatarsal

Explanation

The Lisfranc ligament is an essential and robust interosseous stabilizing structure of the midfoot. It originates on the lateral aspect of the medial cuneiform and courses obliquely to insert on the medial aspect of the base of the second metatarsal. There is no transverse ligament directly connecting the first and second metatarsal bases; therefore, the Lisfranc ligament provides the critical link between the medial and middle columns of the foot.

Question 4433

Topic: Midfoot & Hindfoot

A 34-year-old man sustains a displaced fracture of the talar neck with subluxation of the subtalar joint, while the tibiotalar and talonavicular joints remain congruent (Hawkins Type II). He undergoes prompt open reduction and internal fixation. Which of the following is the most reliable early radiographic indicator that osteonecrosis of the talar body will NOT occur?

. Increased radiodensity of the talar body on a mortise radiograph at 4 weeks
. Subchondral radiolucency of the talar dome on an AP or mortise radiograph at 6 to 8 weeks
. A subchondral cyst in the talar dome on a lateral radiograph at 3 months
. Anatomic alignment of the talonavicular joint on the postoperative CT scan
. Reactive sclerosis of the posterior facet of the subtalar joint at 6 weeks

Correct Answer & Explanation

. Subchondral radiolucency of the talar dome on an AP or mortise radiograph at 6 to 8 weeks

Explanation

The subchondral radiolucency of the talar dome seen on an AP or mortise radiograph at 6 to 8 weeks post-injury is known as Hawkins sign. This radiolucent band indicates that the talar body has sufficient blood supply to undergo normal disuse osteopenia (resorption of bone). Its presence is a highly reliable indicator that the vascular supply to the talar body is intact and that avascular necrosis (AVN) will not occur. Conversely, uniform radiodensity of the talar body compared to the surrounding osteopenic bone suggests ischemia and impending AVN.

Question 4434

Topic: 8. Foot and Ankle
A 29-year-old male falls from a ladder and sustains a displaced fracture of the talar neck. Plain radiographs and CT imaging demonstrate displacement of the talar neck with subluxation of the subtalar joint, while the tibiotalar (ankle) joint remains completely congruous. According to the Hawkins classification, what is the type of fracture and the approximate risk of avascular necrosis (AVN) of the talar body?
. Type I; 0-10% risk
. Type II; 20-50% risk
. Type III; 70-100% risk
. Type IV; 70-100% risk
. Type II; 70-100% risk

Correct Answer & Explanation

. Type II; 20-50% risk

Explanation

The Hawkins classification describes talar neck fractures based on displacement and joint subluxation/dislocation. Type I is non-displaced (AVN risk 0-10%). Type II involves displacement of the talar neck with subluxation or dislocation of the subtalar joint, while the ankle joint remains intact (AVN risk 20-50%). Type III involves dislocation of both the subtalar and ankle joints (AVN risk >70%). Type IV includes additional subluxation or dislocation of the talonavicular joint. The described injury matches a Type II fracture.

Question 4435

Topic: 8. Foot and Ankle
A 45-year-old male is undergoing open reduction and internal fixation of a Sanders Type III calcaneus fracture via an extensile lateral approach. Which of the following technical execution aspects is most critical for minimizing the risk of postoperative skin edge necrosis and wound breakdown?
. Creating a full-thickness subperiosteal flap while avoiding a 'no-touch' retraction technique
. Raising the flap as a single, full-thickness subperiosteal envelope containing the sural nerve
. Placing the vertical limb of the incision just posterior to the Achilles tendon
. Handling the skin edges frequently with toothed forceps to ensure precise anatomic closure
. Dissecting the subcutaneous tissues separate from the periosteum to maximize soft tissue mobility

Correct Answer & Explanation

. Raising the flap as a single, full-thickness subperiosteal envelope containing the sural nerve

Explanation

Wound complications are a significant risk with the extensile lateral approach to the calcaneus. To minimize this risk, the flap must be raised as a single, full-thickness subperiosteal envelope that includes the sural nerve, lesser saphenous vein, and peroneal tendons to preserve its tenuous vascular supply. Dissecting the flap in distinct layers, rather than full-thickness to bone, drastically increases the risk of necrosis. A 'no-touch' technique utilizing K-wires for retraction is heavily favored over handling the tissue with forceps.

Question 4436

Topic: 8. Foot and Ankle
A 32-year-old male sustains a high-energy fall, resulting in a Hawkins Type III fracture of the talar neck. What is the approximate risk of avascular necrosis (AVN) of the talar body associated with this specific injury pattern, and what vascular supply is primarily disrupted?
. 10-20%; Artery of the tarsal canal
. 30-50%; Artery of the tarsal sinus
. 70-100%; Artery of the tarsal canal, tarsal sinus, and deltoid branches
. 0-10%; Dorsalis pedis artery
. 50-60%; Posterior tibial artery only

Correct Answer & Explanation

. 70-100%; Artery of the tarsal canal, tarsal sinus, and deltoid branches

Explanation

A Hawkins Type III fracture of the talar neck is characterized by a displaced fracture of the talar neck with dislocation of both the subtalar and tibiotalar joints. This severe displacement predictably disrupts the three major sources of blood supply to the talar body: the artery of the tarsal canal (from the posterior tibial artery), the artery of the tarsal sinus (anastomotic sling), and the deltoid branches. Because of this catastrophic devascularization, the risk of avascular necrosis (AVN) of the talar body is extremely high, approaching 70-100%.

Question 4437

Topic: 8. Foot and Ankle
A 25-year-old male falls from a height of 15 feet and sustains a Hawkins type III talar neck fracture (talar neck fracture with subtalar and tibiotalar dislocations). The primary blood supply to the talar body, which is at the highest risk of disruption in this specific injury pattern, is derived from which of the following structures?
. Artery of the tarsal sinus
. Artery of the tarsal canal
. Deltoid branch of the posterior tibial artery
. Dorsalis pedis artery
. Peroneal artery

Correct Answer & Explanation

. Artery of the tarsal canal

Explanation

The artery of the tarsal canal is a branch of the posterior tibial artery and provides the dominant blood supply to the talar body. In a Hawkins type III fracture, the fracture of the neck disrupts the intraosseous antegrade supply, the subtalar dislocation disrupts the artery of the tarsal canal and sinus tarsi, and the tibiotalar dislocation disrupts the deltoid branches. Because the artery of the tarsal canal supplies the majority of the talar body, its disruption heavily contributes to the high rate of avascular necrosis (AVN) seen in Hawkins III fractures.

Question 4438

Topic: 8. Foot and Ankle

A 24-year-old collegiate football player sustains a high-energy hyperplantarflexion injury to his midfoot. Weight-bearing radiographs demonstrate a 3mm diastasis between the base of the first and second metatarsals, without any obvious bony fractures. MRI confirms a complete, purely ligamentous rupture of the Lisfranc ligament complex. What is the most appropriate surgical management to minimize long-term reoperation rates and maximize functional outcome?

. Closed reduction and percutaneous Kirschner wire fixation
. Primary arthrodesis of the first, second, and third tarsometatarsal joints
. Open reduction and rigid transarticular screw fixation
. Open reduction and dorsal bridge plating
. Dynamic stabilization utilizing a suture-button device

Correct Answer & Explanation

. Primary arthrodesis of the first, second, and third tarsometatarsal joints

Explanation

Recent high-level evidence, including landmark studies by Ly and Coetzee, has demonstrated that for purely ligamentous Lisfranc injuries, primary arthrodesis of the medial column (1st-3rd tarsometatarsal joints) yields superior functional outcomes and significantly lower reoperation rates compared to open reduction and internal fixation (ORIF). ORIF is generally preferred for bony Lisfranc fracture-dislocations.

Question 4439

Topic: 8. Foot and Ankle

A 22-year-old collegiate athlete presents with midfoot pain after his foot was axially loaded while plantarflexed. On examination, there is pronounced plantar ecchymosis and tenderness over the tarsometatarsal joints. Non-weight-bearing radiographs of the foot are interpreted as normal. What is the most appropriate next step to evaluate for a subtle Lisfranc injury?

. Computed tomography (CT) scan of the foot without contrast
. Magnetic resonance imaging (MRI) of the foot
. Weight-bearing radiographs of the foot
. Technetium-99 bone scan
. Diagnostic ultrasound of the midfoot ligaments

Correct Answer & Explanation

. Weight-bearing radiographs of the foot

Explanation

Subtle Lisfranc (tarsometatarsal) injuries may not be apparent on standard non-weight-bearing radiographs. Plantar ecchymosis is a highly specific clinical sign for a Lisfranc injury. The recommended next step in diagnosis is to obtain weight-bearing (stress) radiographs, as the axial load stresses the midfoot ligaments and can unmask subtle diastasis (often seen between the bases of the first and second metatarsals). If these are equivocal, advanced imaging like weight-bearing CT or MRI may then be considered.

Question 4440

Topic: 8. Foot and Ankle

A 40-year-old man falls from a ladder and sustains a closed, displaced intra-articular calcaneus fracture. Surgical intervention is planned via an extensile lateral approach. To minimize the high risk of wound healing complications associated with this approach, which of the following surgical principles is paramount?

. Immediate surgery within 24 hours regardless of swelling
. Developing a full-thickness fasciocutaneous flap via subperiosteal dissection
. Using a tourniquet for a maximum of 60 minutes
. Avoiding the use of a closed suction drain postoperatively
. Utilizing multiple small incisions rather than a single continuous incision

Correct Answer & Explanation

. Developing a full-thickness fasciocutaneous flap via subperiosteal dissection

Explanation

The extensile lateral approach to the calcaneus carries a significant risk of wound necrosis and infection. The most critical technical factor to preserve the blood supply to the skin flap is the creation of a full-thickness fasciocutaneous flap. Dissection must be performed sharply down to bone, taking the periosteum off the lateral wall of the calcaneus in a single thick layer. Retraction should be achieved using 'no-touch' techniques (e.g., placing K-wires into the talus and fibula) rather than hand-held retractors that crush the skin edges.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page