MCQs – Foot/Ankle 2

Modern Study Review (AI-Generated)

High-Yield Summary

This topic is a staple of the Royal College exam, focusing heavily on foot and ankle nerve anatomy, deformity management, fracture mechanisms, and arthrodesis positioning. The single most important clinical trade-off is often between preserving joint motion (e.g., cheilectomy for hallux rigidus in athletes) versus achieving durable stability (fusion in laborers). Exam questions frequently test recognition of injury mechanisms (e.g., trimalleolar fracture dislocation vs pronation-abduction fractures) and the precise positioning parameters for ankle arthrodesis. While classic teaching favors ORIF for Lisfranc injuries, emerging minimally invasive techniques are under investigation but not yet standard.

High-Yield Decision Matrix

Active Recall Q&A

Nerve Anatomy & Innervation

Q: Which plantar nerve is smaller, medial or lateral?
A: The lateral plantar nerve is smaller than the medial plantar nerve.
Related Pearl: The medial plantar nerve carries more motor fibers, explaining its larger size and broader innervation.

Q: What muscles does the lateral plantar nerve innervate?
A: It innervates the abductor digiti minimi, quadratus plantae, flexor digit minimi, and sometimes the plantar and dorsal interossei of the 4th interosseous space.
Related Pearl: The lateral plantar nerve’s deep branch supplies intrinsic foot muscles critical for toe abduction and flexion.

Q: Which muscles are innervated by the deep branch of the lateral plantar nerve?
A: The adductor hallucis, lateral three lumbricals, and the remaining interosseous spaces.
Related Pearl: Damage to the deep branch can cause claw toe deformities due to loss of intrinsic muscle function.

Q: Which plantar nerve is larger, medial or lateral?
A: The medial plantar nerve is larger than the lateral plantar nerve.
Related Pearl: The medial plantar nerve is analogous to the median nerve in the hand, supplying key muscles for toe flexion.

Q: What muscles does the medial plantar nerve innervate?
A: The abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, and the most medial lumbrical.
Related Pearl: Injury to the medial plantar nerve can cause weakness in toe flexion and abduction, affecting gait.

Hallux Rigidus Management

Q: What is the preferred treatment for hallux rigidus in a laborer?
A: Fusion is preferred for laborers with hallux rigidus.
Related Pearl: Fusion provides durable pain relief and stability for high-demand weight-bearing activities.

Q: What is the preferred treatment for hallux rigidus in an athlete?
A: Cheilectomy is preferred for athletes with hallux rigidus.
Related Pearl: Cheilectomy preserves joint motion, which is critical for athletic performance.

Amputation Prognosis & Healing

Q: What condition predicts the poorest prognosis after a Symes amputation?
A: Vascular disease with heel ulcers predicts the poorest prognosis.
Related Pearl: Heel ulcers in vascular disease patients contraindicate Symes amputation due to poor healing potential.

Q: What is the best predictor of healing in amputation?
A: Transcutaneous oxygen pressure (TcPO2) is the best predictor.
Related Pearl: TcPO2 values correlate with tissue oxygenation and predict wound healing better than clinical exam alone.

Q: What Doppler index threshold is associated with healing potential in amputation?
A: A Doppler index of 0.45 is a critical threshold.
Related Pearl: Values below 0.45 indicate poor distal perfusion and higher risk of non-healing.

Imaging & Diagnosis

Q: What important joint is missed on coronal CT of the calcaneus?
A: The calcaneocuboid joint is missed on coronal CT.
Related Pearl: Axial or sagittal imaging is necessary to fully evaluate the calcaneocuboid joint in trauma.

Clawtoes Management

Q: What is the initial management for flexible clawtoes in a 60-year-old stroke patient, especially if diabetic or vasculopathic?
A: Nonoperative management with crest pads, high toe box shoes, and metatarsal bars or pads.
Related Pearl: Offloading pressure and preventing skin breakdown are priorities in neuropathic and vasculopathic patients.

Q: If nonoperative management fails in flexible clawtoes, what is the next surgical step?
A: Soft tissue release such as Girdlestone-Taylor flexor to extensor transfer.
Related Pearl: This transfer restores extensor balance and reduces clawing by rebalancing tendon forces.

Q: If soft tissue release fails in clawtoes, what surgical options remain?
A: Proximal phalangeal resections (DuVries) or interphalangeal (IP) fusions with dorsal hood resections.
Related Pearl: These procedures address fixed deformities and reduce dorsal pressure points.

Tibialis Posterior Dysfunction

Q: What clinical signs suggest tibialis posterior tendon is inflamed but still in continuity?
A: Ability to do single leg raises, some inversion strength with early fatigue, pain with passive dorsiflexion/eversion, and local tenderness.
Related Pearl: Partial tears or tendinosis often present with preserved but weakened function.

Q: What are treatment options for tibialis posterior dysfunction with tendon in continuity?
A: Continued nonoperative management with bracing or synovectomy plus flexor digitorum longus (FDL) transfer if the foot is otherwise normal.
Related Pearl: FDL transfer compensates for deficient tibialis posterior function and restores medial arch support.

Fracture Patterns & Mechanisms

Q: What is the injury mechanism for trimalleolar fracture dislocations?
A: Eversion/pronation and external rotation injury with the posterior tibiofibular ligament intact.
Related Pearl: The intact posterior tibiofibular ligament avulses the posterior tibia rather than rupturing.

Q: What fracture pattern is caused by a pronation-abduction mechanism?
A: Avulsion off the medial malleolus with a comminuted fibular fracture.
Related Pearl: Recognizing this pattern guides appropriate fixation and ligament repair.

Chevron Procedure

Q: For which hallux valgus deformities is the chevron procedure recommended?
A: Mild and some moderate deformities.
Related Pearl: The chevron osteotomy provides limited correction and is less effective for severe deformities.

Q: What are the most common complications of the chevron procedure?
A: Recurrence, undercorrection, and avascular necrosis (AVN), especially if lateral soft tissue release is performed.
Related Pearl: Lateral release increases risk of AVN by disrupting blood supply to the metatarsal head.

Q: Does the chevron procedure cause significant bone shortening or joint stiffness?
A: No, it does not significantly shorten the bone or cause joint stiffness or pain.
Related Pearl: Preservation of bone length and joint motion makes it favorable for younger patients.

Lisfranc Injuries

Q: What is the standard treatment for Lisfranc injuries?
A: Open reduction and internal fixation (ORIF) is invariably required.
Related Pearl: Anatomic reduction is critical to prevent chronic instability and arthritis.

Q: What factor most influences the prognosis of Lisfranc injuries?
A: How anatomic the reduction is obtained and maintained.
Related Pearl: Initial injury energy affects prognosis but surgical technique is paramount.

Ankle Arthrodesis

Q: What is the ideal position for tibio-talar (ankle) arthrodesis in plantarflexion/dorsiflexion?
A: Neutral position.
Related Pearl: Neutral alignment optimizes gait and prevents compensatory deformities.

Q: What is the ideal valgus angle in ankle arthrodesis?
A: 0-5 degrees of valgus.
Related Pearl: Slight valgus alignment improves foot clearance and weight distribution.

Q: What is the ideal external rotation angle in ankle arthrodesis?
A: 5-10 degrees of external rotation.
Related Pearl: External rotation aligns the foot for normal toe-off during gait.

Q: How should the talus be positioned during ankle arthrodesis?
A: Translated about 1 cm posteriorly to reduce the lever arm of the foot.
Related Pearl: Posterior translation decreases stress on the fusion site and improves mechanical advantage.

Q: When is fusion in equinus acceptable in ankle arthrodesis?
A: Only in polio patients to stabilize the knee in midstance.
Related Pearl: Equinus fusion compensates for quadriceps weakness by providing knee stability.

Ankle Dislocation & Ball and Socket Ankle

Q: What is a common complication of posteromedial ankle dislocation?
A: Neurologic injury.
Related Pearl: The tibial nerve and posterior tibial artery are at risk in this dislocation pattern.

Q: What conditions are associated with ball and socket ankle?
A: Tarsal coalition, fibular hemimelia, hypoplastic lateral femoral condyle, femoral deficiency, and absent lateral foot rays.
Related Pearl: Ball and socket ankle represents a congenital anomaly with multiple limb deficiencies.

Q: Is cavovarus deformity associated with ball and socket ankle?
A: No, cavovarus is not associated.
Related Pearl: Cavovarus is a separate deformity typically related to neuromuscular disorders.

Classic Clinical Notes

• Lateral Plantar Nerve
• smaller than medial
• innervates abductor digiti minimi and quadratus plantae, flexor digit minimi, and sometimes the plantar and dorsal interossei of the 4th interosseous space
• the deep branch then innervates the adductor hallucis, the lateral 3 lumbricals, and the remaining interosseous spaces

• Medial Plantar Nerve
• the larger of the two plantar nerves
• innervates the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, and the most medial lumbrical

• a laborer with hallux rigidis should probably get a fusion; an athlete with hallux rigidis should probably have a cheilectomy

• the poorest prognosis in Symes amputation is vascular disease – these get heel ulcers which are basically a contraindication to a Symes.

• best thing to predict healing in amputation – transcutaneous oxygen pressure TcPO2; also, toe pressures, and Doppler indices of 0.45

• coronal CT of the calcaneus will miss the calcaneocuboid joint

• in the 60 year old stroke patient with flexible clawtoes – initial management, especially in diabetics and vasculopaths, is nonoperative – crest pads to lift toes off ground, high toe box shoe that doesn’t rub on the dorsal aspects of the toes, and a metatarsal bar or pad to relieve the pressure on the heads. Failing this, if flexible, try some form of soft tissue release such as a Girdlestone-Taylor flexor to extensor transfer. Failing this, do proximal phalangeal resections (DuVries) or IP fusions with dorsal hood resections. (???)

• for a patient with tib post dysfunction: if they are still able to do single leg raises and have some inversion strength although fatigue early, and they have pain with passive dorsiflexion/eversion, and local tenderness, they probably still have a tib post in continuity, but it is inflamed and somewhat attenuated (maybe partially torn). Options include further nonop with bracing, etc, or try synovectomy and FDL transfer if the foot is otherwise normal.

• trimalleolar fracture dislocations are eversion/pronation, external rotation injuries with the posterior tibiofibular ligament remaining INTACT and pulling off the posterior part of the tibia.

• the chevron procedure does not result in MTP ankylosis; its most common complications are recurrence or undercorrection and offers a limited correction of the deformity. Therefore, it is recommended only for mild and some moderate deformities. AVN is the most dreaded complication, and is increased if you do a lateral soft tissue release. It does not significantly shorten the bone, and does not lead to joint stiffness or pain.

• Lisfranc injuries invariably require ORIF. The ultimate result is probably most likely related to how anatomic the reduction is obtained and maintained. Some feel that the initial injury energy is the most important factor, but more seem to believe that how well you treat it is the most important. It is agreed upon that initial energy of injury does have some prognostic importance (just how much is debatable)

• an avulsion off the medial malleolus with a comminuted fibular fracture is often caused by the pronation-abduction mechanism.

• position of tibio-talar (ankle) arthrodesis: neutral plantarflexion/dorsiflexion, 0-5 of valgus, 5-10 of external rotation. Also, translate the talus about a centimeter posterior to diminish the lever arm of the rest of the foot. The only time you might fuse in a bit of equinus is in the polio patient, where the equinus is helpful in stabilizing the knee in midstance.

• posteromedial ankle dislocation – commonly associated with neurologic injury

• ball and socket ankle is associated with: tarsal coalition, fibular hemimelia, hypoplastic lateral femoral condyle, femoral deficiency, absent rays on lateral aspect of foot. It is not associated with cavovarus.

Last Updated on January 25, 2026 by Christian Veillette