ABOS Part I Orthopedic Review: Lisfranc Injuries, Foot Compartment Syndrome, Ankle Fractures | Part 22158

Correct Answer: E

While all listed options are potential signs of compartment syndrome, 'pain with passive stretching of the toes' (for the deep posterior and anterior compartments) and 'severe pain unresponsive to increasing doses of opioids' (pain out of proportion to injury) are considered the most sensitive and earliest signs of evolving compartment syndrome. Paresthesia can be an early sign but may also indicate nerve injury unrelated to compartment syndrome. Diminished pulses and pallor are late signs, often indicating irreversible muscle ischemia and nerve damage, and are less reliable early indicators because compartment pressure often exceeds venous pressure long before arterial flow is compromised.

Correct Answer: D

The Lauge-Hansen classification system categorizes ankle fractures based on the position of the foot at the time of injury and the deforming force applied. It describes a sequential pattern of injury to ligaments and bones, which can help predict the extent of damage and guide reduction. The Danis-Weber classification is based on the level of the fibular fracture relative to the syndesmosis. The Gustilo-Anderson classification is for open fractures. The AO classification is a comprehensive alphanumeric system for all fractures. The Salter-Harris classification is for physeal injuries in children.

Correct Answer: C

The case explicitly states, 'There is diastasis of > 2 mm between the base of the first and second metatarsals, features suggestive of Lisfranc tarsometatarsal fracture dislocation. There is a small avulsed fragment of bone in that interval. This avulsion fracture could be from the insertion of the Lisfranc ligament into the base of the second metatarsal, called a ‘fleck sign’.' This diastasis is a hallmark radiographic sign of a Lisfranc injury, indicating disruption of the Lisfranc ligament complex.

Option A (Fracture of the cuboid bone) is incorrect. While cuboid fractures can occur in foot trauma, they are not the primary diagnostic feature of a Lisfranc injury.

Option B (Widening of the space between the navicular and cuneiform bones) is incorrect. While midfoot widening is a general sign of trauma, the specific diastasis between the first and second metatarsal bases is more characteristic of a Lisfranc injury, reflecting disruption at the tarsometatarsal joint complex.

Option D (Avulsion fracture from the lateral malleolus) is incorrect. An avulsion fracture of the lateral malleolus is indicative of an ankle injury, not a midfoot Lisfranc injury.

Option E (Subtalar joint dislocation) is incorrect. Subtalar joint dislocation is a hindfoot injury and presents differently from a Lisfranc injury, which affects the midfoot.

Correct Answer: C

The case specifically highlights the importance of excluding compartment syndrome in the initial management of a Lisfranc injury. The candidate states, 'Compartment syndrome must be excluded.' and 'On admission to hospital I would arrange for regular clinical examinations and monitoring in order not to miss an early developing compartment syndrome.' Lisfranc injuries, especially high-energy mechanisms, are associated with significant soft tissue swelling and can lead to acute compartment syndrome of the foot, which requires emergent surgical decompression to prevent permanent tissue damage.

Option A (Detailed assessment of ankle range of motion) is incorrect. While a general examination is important, the immediate priority in a midfoot trauma with significant swelling is to rule out limb-threatening conditions like compartment syndrome.

Option B (Evaluation for signs of deep vein thrombosis (DVT)) is incorrect. DVT is a potential complication of lower limb immobilization but is not an acute, limb-threatening emergency in the immediate post-injury period like compartment syndrome.

Option D (Assessment of hip and knee joint stability) is incorrect. While a thorough trauma assessment includes joints proximal and distal, the most critical acute assessment directly related to the foot injury itself is compartment syndrome.

Option E (Measurement of foot arch height) is incorrect. This is a biomechanical assessment that is not acutely critical in the emergency management of a Lisfranc fracture-dislocation.

Correct Answer: C

The case directly addresses this scenario: 'What would you do if the radiographs were inconclusive in diagnosing this condition? CANDIDATE: I would consider further radiographic imaging, oblique and lateral view, stress views and a CT scan or may opt for an MRI scan.' Stress views can reveal instability not apparent on static radiographs, and a CT scan provides detailed bony anatomy, crucial for identifying subtle fractures, displacement, and joint incongruity in the complex midfoot region.

Option A (Repeat AP and oblique radiographs in 24 hours) is incorrect. Delaying definitive diagnosis can lead to worse outcomes for Lisfranc injuries. Repeat static radiographs are unlikely to provide more information if the initial ones were inconclusive.

Option B (Obtain a bone scan) is incorrect. While a bone scan can show increased metabolic activity, it is not specific enough for acute fracture-dislocation diagnosis and is not typically used as a primary diagnostic tool for Lisfranc injuries.

Option D (Order a weight-bearing lateral ankle radiograph) is incorrect. While a lateral view is part of a complete series, a weight-bearing ankle view is not the most appropriate next step for a suspected midfoot injury, and it may not provide the necessary detail for the tarsometatarsal joints.

Option E (Administer a local anesthetic injection and re-examine) is incorrect. This might help with pain but will not provide the necessary anatomical detail to diagnose a subtle Lisfranc injury.

Correct Answer: B

The case states: 'There is a role for non-operative management of an undisplaced stable injury or sprain which includes a non-weightbearing cast for 6 weeks and regular clinical and radiological review. However, in the presence of subluxation or dislocation, accurate reduction and stable fixation is essential.' The 3 mm increase in diastasis on stress views indicates instability, which is equivalent to a subluxation or dislocation, even if not apparent on static views. Therefore, open reduction and internal fixation (ORIF) is required to achieve accurate reduction and stable fixation.

Option A (Non-weightbearing cast for 6 weeks with regular clinical and radiological review) is incorrect. This is appropriate only for undisplaced, stable injuries or sprains. The positive stress views indicate instability, making non-operative management inadequate.

Option C (Primary arthrodesis of the tarsometatarsal joints) is incorrect. Primary arthrodesis is typically reserved for severely comminuted fractures or chronic instability, not for an acute, reducible unstable injury without severe comminution.

Option D (Non-weightbearing cast for 2 weeks, then progressive weight-bearing) is incorrect. This duration is too short for a Lisfranc injury, even for stable sprains, and progressive weight-bearing would be contraindicated in an unstable injury.

Option E (Physical therapy with early range of motion exercises) is incorrect. Early range of motion would exacerbate the instability and prevent healing, leading to chronic pain and deformity.

Correct Answer: C

The case states: 'With a severely comminuted fracture, primary arthrodesis of tarsometatarsal joints may be required.' In cases of severe comminution and irreducible displacement, especially in patients with comorbidities that might affect healing (like diabetes and neuropathy), primary arthrodesis offers a more stable and predictable outcome by fusing the damaged joints, reducing the risk of post-traumatic arthritis and chronic pain associated with joint incongruity.

Option A (Closed reduction and percutaneous pinning) is incorrect. This technique is generally reserved for less severe, reducible injuries without significant comminution or displacement.

Option B (Open reduction and internal fixation (ORIF) with screws and plating) is incorrect. While ORIF is the standard for most displaced Lisfranc injuries, it may not be feasible or durable in the presence of severe comminution where anatomical reduction and stable fixation of fragments are difficult to achieve. In such cases, primary arthrodesis is often preferred.

Option D (External fixation with delayed definitive management) is incorrect. External fixation might be used for temporary stabilization in cases of severe soft tissue injury or open fractures, but it is not the definitive treatment for a severely comminuted, irreducible Lisfranc injury in a stable patient.

Option E (Non-weightbearing cast immobilization for 12 weeks) is incorrect. Non-operative management is only for undisplaced, stable injuries. A severely comminuted and irreducible injury requires surgical intervention.

Correct Answer: C

The case explicitly states regarding prognosis: 'This is a serious injury with potentially a poor outcome. Post-traumatic osteoarthritis may occur in more than 50% of cases despite surgical intervention. Residual pain and stiff foot are not uncommon complications of this injury.' The patient's symptoms of persistent pain and stiffness are highly consistent with the development of post-traumatic osteoarthritis in the tarsometatarsal joints, which is a common and significant long-term complication of Lisfranc injuries.

Option A (Avascular necrosis of the talus) is incorrect. Avascular necrosis of the talus is a complication associated with talar neck fractures or severe ankle dislocations, not typically Lisfranc injuries.

Option B (Chronic ankle instability) is incorrect. Lisfranc injuries affect the midfoot, and while they can alter foot mechanics, chronic ankle instability is not a direct or primary long-term complication of a Lisfranc injury itself.

Option D (Stress fracture of the fifth metatarsal) is incorrect. While stress fractures can occur in the foot, they are not a direct long-term complication of a Lisfranc injury, especially after ORIF and rehabilitation.

Option E (Tarsal tunnel syndrome) is incorrect. Tarsal tunnel syndrome involves compression of the posterior tibial nerve and can cause foot pain, but it is not listed as a common long-term complication of Lisfranc injuries in the case, nor is it as prevalent as post-traumatic osteoarthritis.

Correct Answer: C

The patient's symptoms (increasing pain disproportionate to injury, tense/swollen foot, pain with passive toe extension, weak dorsalis pedis pulse) are classic signs of acute compartment syndrome of the foot. The case emphasizes, 'Compartment syndrome must be excluded' and 'On admission to hospital I would arrange for regular clinical examinations and monitoring in order not to miss an early developing compartment syndrome.' While clinical diagnosis is paramount, urgent compartment pressure measurements can objectively confirm the diagnosis, especially when clinical signs are equivocal or in a patient with altered sensation. Once diagnosed clinically, emergency decompression is required.

Option A (Administer additional opioid analgesia and re-evaluate in 4 hours) is incorrect. This would delay critical intervention for compartment syndrome, potentially leading to irreversible tissue damage.

Option B (Elevate the limb further and apply ice packs) is incorrect. While elevation is part of initial management, it can worsen compartment syndrome by reducing perfusion pressure. Ice packs are generally contraindicated in suspected compartment syndrome as they can cause vasoconstriction.

Option D (Order an urgent MRI to assess soft tissue damage) is incorrect. MRI is not the primary diagnostic tool for acute compartment syndrome and would cause an unacceptable delay in diagnosis and treatment.

Option E (Consult physical therapy for early mobilization) is incorrect. Early mobilization is contraindicated in suspected compartment syndrome and would worsen the condition.

Correct Answer: C

The case explicitly details the surgical approach for foot compartment syndrome: 'There is more than one technique described to decompress compartment syndrome of the foot, but I have been trained to decompress the nine compartments of the foot through three incisions, two dorsal over the second and third metatarsals and one on the medial side, just under the medial border of the first metatarsal.' This describes a common and effective approach to decompress all nine compartments of the foot.

Option A (One incision, located medially along the arch) is incorrect. A single incision is insufficient to decompress all nine compartments of the foot.

Option B (Two incisions, one dorsal and one plantar) is incorrect. While some techniques use dorsal and plantar approaches, the specific description in the case involves three incisions with precise locations.

Option D (Four incisions: two dorsal and two plantar) is incorrect. This is not the technique described in the case, which specifies three incisions.

Option E (Five incisions: one for each metatarsal space) is incorrect. This would be excessive and is not the standard approach described for foot fasciotomy.

Correct Answer: B

The case states: 'There is a role for non-operative management of an undisplaced stable injury or sprain which includes a non-weightbearing cast for 6 weeks and regular clinical and radiological review.' Even a stable Lisfranc sprain involves disruption of critical ligaments and requires a period of strict non-weightbearing immobilization to allow for healing and prevent progression to instability. Regular review is essential to ensure stability is maintained.

Option A (Immediate weight-bearing as tolerated with a supportive shoe) is incorrect. This would place undue stress on the healing ligaments and could lead to chronic instability and pain.

Option C (Partial weight-bearing in a walking boot for 2-3 weeks) is incorrect. This duration and level of activity are insufficient for a Lisfranc sprain, which requires longer non-weightbearing to heal adequately.

Option D (Aggressive physical therapy focusing on strengthening and flexibility) is incorrect. While physical therapy is crucial after immobilization, aggressive therapy too early would jeopardize ligament healing.

Option E (Corticosteroid injection into the tarsometatarsal joint) is incorrect. Corticosteroid injections are generally not indicated for acute ligamentous injuries and could potentially weaken the healing tissue.

Correct Answer: C

The Lisfranc ligament is a critical stabilizer of the midfoot. The case mentions the 'fleck sign' as an avulsion fracture from the insertion of the Lisfranc ligament into the base of the second metatarsal. This ligament primarily connects the medial cuneiform to the base of the second metatarsal. It is the strongest ligament in the tarsometatarsal joint complex and prevents dorsal and lateral displacement of the metatarsals relative to the tarsus, thus providing crucial stability to the midfoot arch.

Option A (Connects the navicular to the cuboid, stabilizing the transverse arch) is incorrect. This describes ligaments within the midtarsal joint, not the Lisfranc ligament.

Option B (Connects the calcaneus to the cuboid, supporting the lateral column) is incorrect. This describes the calcaneocuboid ligaments, part of the Chopart joint.

Option D (Connects the talus to the navicular, forming part of the talonavicular joint capsule) is incorrect. This describes ligaments of the talonavicular joint, part of the hindfoot.

Option E (Connects the first metatarsal to the medial cuneiform, preventing hallux valgus) is incorrect. While there are ligaments connecting the first metatarsal to the medial cuneiform, the Lisfranc ligament specifically refers to the connection between the medial cuneiform and the second metatarsal base, and its primary role is midfoot stability, not directly preventing hallux valgus.

Primary arthrodesis for purely ligamentous Lisfranc injuries has been shown to yield similar or slightly better functional outcomes compared to ORIF, primarily due to a significantly decreased need for subsequent surgeries such as hardware removal.

Missed foot compartment syndrome leads to ischemic necrosis and contracture of the intrinsic muscles of the foot. This intrinsic-minus state typically results in the classic clinical presentation of claw toe deformities.

The SER sequence classically begins with rupture of the AITFL (Stage I), followed by a spiral fibular fracture (Stage II), PITFL rupture or posterior malleolus fracture (Stage III), and finally deltoid rupture or medial malleolus fracture (Stage IV).

The Lisfranc ligament is an interosseous ligament that connects the lateral aspect of the medial cuneiform to the medial base of the second metatarsal. There is no direct ligamentous connection between the bases of the first and second metatarsals.

Diabetic patients with neuropathy are at a severe risk for Charcot arthropathy and catastrophic hardware failure. Augmented, ultra-rigid fixation combined with prolonged non-weight-bearing (often double the standard duration) is the recommended strategy.

The classic dual dorsal incisions provide direct and easy access to release the four interosseous compartments of the foot. Reaching the deeper central and calcaneal compartments from a strictly dorsal approach requires extensive and potentially dangerous dissection.

Fixation of a large posterior malleolus fragment directly restores the anatomic attachment of the posterior inferior tibiofibular ligament (PITFL). This provides significantly greater syndesmotic stability and stiffness than isolated trans-syndesmotic screw fixation.

The Lisfranc ligament is a strong interosseous ligament connecting the lateral aspect of the medial cuneiform to the medial base of the second metatarsal. It is critical for the stability of the midfoot arch.

Current evidence demonstrates that pure ligamentous Lisfranc injuries have better functional outcomes and lower reoperation rates when treated with primary arthrodesis of the medial three rays compared to open reduction and internal fixation.

In an SER injury, the sequence begins anteriorly and progresses clockwise. Stage I is a rupture of the anterior inferior tibiofibular ligament (AITFL).

To adequately release all nine compartments of the foot (interosseous, central, medial, lateral, and calcaneal), the classic recommended approach utilizes two dorsal incisions and one medial utility incision.

A Bosworth fracture-dislocation is characterized by the proximal fragment of the fractured fibula becoming rigidly entrapped behind the posterior tibial tubercle. This prevents closed reduction and necessitates emergent open reduction.

The 'fleck sign' is pathognomonic for a Lisfranc injury and represents a bony avulsion of the Lisfranc ligament from its attachment at the base of the second metatarsal.

Untreated compartment syndrome of the foot typically leads to ischemic contracture of the intrinsic muscles. This muscle imbalance results in a classic claw toe deformity.

Diabetic patients with neuropathy are at high risk for Charcot arthropathy, fixation failure, and nonunion. Utilizing augmented, rigid fixation techniques (e.g., extra syndesmotic screws or trans-calcaneal pins) is recommended to prevent construct failure.

The PER sequence proceeds as follows: 1) Medial injury (deltoid/malleolus), 2) AITFL rupture, 3) High fibular fracture, and 4) PITFL rupture or posterior malleolus fracture.

The central compartment of the foot contains the flexor digitorum brevis, quadratus plantae, lumbricals, and the flexor hallucis longus tendon. The abductor hallucis is in the medial compartment.

The two dorsal incisions for foot fasciotomy are placed slightly medial to the second metatarsal and slightly lateral to the fourth metatarsal. This allows access to the interosseous compartments and the deep central compartment.

The 4th and 5th TMT joints are highly mobile and act to accommodate uneven terrain. Arthrodesis of these lateral columns is generally avoided to prevent a stiff, painful foot.

Pain out of proportion to the injury and severe pain with passive stretch of the involved muscles (e.g., passive toe dorsiflexion stretching the intrinsic flexors) are the earliest and most reliable signs of compartment syndrome.

A pronation-abduction injury classically results in a transverse or comminuted fibular fracture at the level of the syndesmosis, often presenting with a lateral butterfly fragment due to bending forces.

Anatomical fixation of the posterior malleolus restores the footprint of the posterior inferior tibiofibular ligament (PITFL). This restores syndesmotic stability, often obviating the need for syndesmotic screws.

A Maisonneuve fracture involves disruption of the medial structures, interosseous membrane, and proximal fibula, leading to an unstable syndesmosis. The primary treatment relies on anatomical reduction and fixation of the syndesmosis.

A positive Cotton test indicates syndesmotic instability after lateral (and medial) fixation. A syndesmotic screw or flexible fixation device is required to stabilize the distal tibiofibular joint.

The Lisfranc ligament is a strong interosseous ligament that connects the medial cuneiform to the base of the second metatarsal. It is critical for the stability of the midfoot arch.

There are nine distinct compartments in the foot: medial, lateral, superficial, calcaneal, adductor, and four interosseous compartments. Thorough decompression of all nine is required in cases of foot compartment syndrome.

The Lisfranc ligament is an intra-articular ligament that courses from the lateral aspect of the medial cuneiform to the medial aspect of the second metatarsal base. It is essential for the stability of the tarsometatarsal articulation.

A Delta P (diastolic pressure minus compartment pressure) of less than 30 mmHg is the most reliable threshold for diagnosing compartment syndrome. Loss of pulses is a late and unreliable sign of compartment syndrome.

Unrecognized foot compartment syndrome leads to ischemic contracture of the intrinsic muscles of the foot. This most classically results in a rigid claw toe deformity.

In the Lauge-Hansen SER mechanism, the sequence is: (1) AITFL rupture, (2) spiral fibular fracture, (3) PITFL rupture or posterior malleolus fracture, and (4) medial malleolus fracture or deltoid rupture.

Multiple studies (such as those by Ly and Coetzee) have demonstrated that purely ligamentous Lisfranc injuries have better functional outcomes and lower reoperation rates with primary arthrodesis compared to ORIF.

Diabetic patients with neuropathy are at high risk for fixation failure and Charcot arthropathy. Enhanced fixation (e.g., locking plates, multiple syndesmotic screws, hindfoot nails) and prolonged immobilization (2-3 times normal) are recommended.

The central compartment is the largest of the foot compartments and most commonly records the highest pressures in foot compartment syndrome. It contains the flexor digitorum brevis, lumbricals, and adductor hallucis.

The posterior inferior tibiofibular ligament (PITFL) attaches to the posterior malleolus. Anatomic fixation of a posterior malleolar fracture restores the tension and function of the PITFL, providing significant syndesmotic stability.

The fleck sign represents a bony avulsion of the Lisfranc ligament, most commonly pulling off a small fragment from the plantar-medial aspect of the base of the second metatarsal.

The PER mechanism typically results in a high fibular fracture (Weber C type), which is a short oblique or spiral fracture located above the level of the syndesmosis.

A Bosworth fracture-dislocation is characterized by the proximal fragment of the fractured fibula becoming rigidly entrapped behind the posterior tubercle of the distal tibia, rendering it irreducible by closed means.

In chronic, missed Lisfranc injuries with fixed deformity and secondary arthritic changes, corrective arthrodesis of the medial column (TMT joints) is required to restore anatomy and eliminate pain.

The Tillaux-Chaput fragment is an avulsion of the AITFL from the anterolateral distal tibia. The Wagstaffe fragment is an AITFL avulsion from the anterior fibula, and the Volkmann fragment involves the posterior tibia (PITFL).

The medial dorsal incision is typically placed slightly medial to the second metatarsal shaft. This places the deep peroneal nerve and dorsalis pedis artery, which course in the first intermetatarsal space, at significant risk.

The most common mechanism for sports-related Lisfranc injuries is axial loading onto a plantarflexed foot, which forcibly hyperplantarflexes the midfoot and ruptures the stabilizing ligaments.

An isolated medial malleolus fracture with medial clear space widening suggests a syndesmotic injury. The examiner must evaluate the entire fibula to rule out a Maisonneuve fracture (proximal fibula fracture).

The deep deltoid ligament is the strongest component of the medial ankle complex and provides the primary restraint against lateral translation and external rotation of the talus.

The calcaneal compartment communicates intimately with the deep posterior compartment of the leg along the neurovascular bundle, serving as a conduit for fluid, blood, or infection.

Subtle Lisfranc instability often reduces at rest. Weight-bearing radiographs of both feet are required to unmask ligamentous instability, manifesting as diastasis of the 1st and 2nd metatarsal bases.

A tibiofibular clear space greater than 5-6 mm on either the AP or mortise view is widely accepted as abnormal and indicative of a syndesmotic widening.

The Lisfranc ligament is an interosseous ligament that originates on the lateral aspect of the medial cuneiform and inserts onto the medial base of the second metatarsal. It is the strongest of the tarsometatarsal ligaments and critical for midfoot stability.

There are 9 distinct fascial compartments in the foot: medial, lateral, superficial, calcaneal, four interosseous, and central. The calcaneal compartment contains the quadratus plantae muscle and the lateral plantar nerve.

The SER mechanism progresses in four stages: 1) Anterior inferior tibiofibular ligament (AITFL) rupture, 2) Spiral/oblique fracture of the lateral malleolus, 3) Posterior inferior tibiofibular ligament (PITFL) rupture or posterior malleolus fracture, and 4) Deltoid rupture or medial malleolus fracture.

Prospective randomized trials have shown that primary arthrodesis for purely ligamentous Lisfranc injuries results in comparable or superior functional outcomes while significantly decreasing the need for hardware removal and secondary salvage procedures compared to ORIF.

On a true AP radiograph, the tibiofibular clear space should be less than 6 mm (measured 1 cm proximal to the plafond). This is the most reliable radiographic parameter for evaluating syndesmotic reduction regardless of patient positioning.

The central compartment of the foot is best accessed via a medial approach by advancing the needle superior to the abductor hallucis muscle, directed toward the plantar aspect of the central metatarsals. Approaching through the plantar skin is avoided due to the risk of painful scarring.

Recent guidelines emphasize fixing the posterior malleolus to restore the incisura fibularis and the posterior inferior tibiofibular ligament (PITFL) attachment. This optimally restores syndesmotic stability and joint congruity, shifting focus away from strict fragment size percentage thresholds.

The "fleck sign" represents a bony avulsion of the Lisfranc ligament, typically from the medial base of the second metatarsal. It is highly pathognomonic for a severe Lisfranc injury and indicates significant midfoot instability.