Foot injuries

1. THE 2-MINUTE KINEMATICS

Understanding the biomechanical forces and precise anatomical divisions of the foot—the hindfoot (talus, calcaneus), midfoot (cuneiforms, navicular, cuboid), and forefoot (metatarsals, phalanges)—is critical to predicting injury patterns.

• Calcaneal Fractures: The calcaneus is the largest tarsal bone. Fractures are classically caused by high-energy axial loading, such as falling from a significant height and landing directly on the feet. The massive kinetic energy shatters the calcaneus and frequently transmits force straight up the axial skeleton.
• Lisfranc (Tarsometatarsal) Injuries: Occur when the midfoot is subjected to severe twisting/torsional forces or axial loading on a plantar-flexed foot. This disrupts the critical Lisfranc joint complex separating the midfoot from the forefoot.
• Talus and Navicular Fractures: Typically caused by direct blows, axial loading, or severe pulling/rotational forces resulting in avulsion injuries.
• Pantalar Dislocation: A rare and devastating injury resulting from extreme forces that cause simultaneous disruption of the subtalar, tibiotalar, and talonavicular joints.

2. THE BEDSIDE ACTION PLAN

• Threatened Limbs & Vascular Compromise: If vascular compromise is present (dusky foot, absent dorsalis pedis/posterior tibial pulses) or the skin is severely tented by a dislocation/fracture-dislocation, immediate closed reduction by the emergency physician is warranted without waiting for prereduction radiographs. Provide procedural sedation, grasp the heel and foot, apply traction and opposite rotation, and immediately reassess distal perfusion.
• Open Fractures: Control hemorrhage with sterile pressure dressings after removing gross debris. Do not reduce exposed bone unless there is severe vascular compromise. Irrigate with saline, cover with saline-soaked sponges, splint in place, and initiate early IV antibiotics (typically a first-generation cephalosporin, adding an aminoglycoside for Gustilo Type II or III) and tetanus prophylaxis.
• Splinting & Positioning: For calcaneal, talar, and unstable midfoot injuries, immobilize in a well-padded posterior splint. Mandate strict non-weight-bearing (NWB) status, provide robust analgesia, and keep the foot strictly elevated to the level of the heart to minimize the massive swelling associated with these injuries.

3. THE DIAGNOSTIC GRID

• Targeted Physical Exam: Methodically palpate all specific anatomic zones, paying strict attention to the navicular bone and the base of the fifth metatarsal. Pain elicited by torsion of the midfoot or passive dorsiflexion/plantarflexion should specifically raise suspicion for a Lisfranc injury.
• Mandatory Neurovascular Checks: Assess the dorsalis pedis and posterior tibial pulses, document digital capillary refill, and evaluate motor function (e.g., inability to dorsiflex the toes suggests tibial nerve injury; inability to plantarflex the great toe is suspicious for peroneal nerve injury).
• Indications for CT/Angiography: Plain radiographs have a low sensitivity for complex foot injuries. A non-contrast CT scan of the foot is highly recommended for calcaneus, talus, Lisfranc, and navicular fractures, as it detects occult fractures/subluxations and is necessary for orthopedic surgical planning. CT Angiography is indicated for high-energy trauma (e.g., gunshot wounds) presenting with diminished pulses or signs of vascular injury.

4. THE VISUAL BOARD

• Boehler's Angle: An essential measurement on the lateral radiograph for evaluating calcaneus fractures. It is the intersection of two lines: (1) from the highest part of the anterior process to the highest point of the posterior articular surface, and (2) from the highest point of the posterior articular surface to the superior part of the calcaneal tuberosity. Normal is 25 to 40 degrees; an angle <25 degrees is highly suspicious for a calcaneus fracture.
• Lisfranc Disruption: On the anteroposterior (AP) view, look for the classic "Fleck sign" (a small bony avulsion fragment between the medial cuneiform and second metatarsal base). Other unstable signs include >2 mm widening between the medial cuneiform and second metatarsal, lateral displacement of the second metatarsal, or dorsal subluxation of the metatarsals on the lateral view.

5. THE CLASSIFICATION MATRIX

• The Ottawa Foot Rules: A highly validated decision rule to reduce unnecessary imaging. A foot radiographic series is indicated only if there is pain in the midfoot zone PLUS one of the following: bone tenderness at the navicular, bone tenderness at the base of the fifth metatarsal, OR an inability to bear weight (for at least 4 steps) both immediately and in the ED.
• Gustilo-Anderson Classification: Used for open fractures to guide operative management and antibiotic coverage. Type I (<1 cm wound), Type II (1-10 cm without extensive soft tissue damage), Type IIIA (extensive soft tissue stripping but adequate bone coverage), Type IIIB (requires a flap for coverage), and Type IIIC (any open fracture with a major vascular injury requiring repair).
• Hawkins Classification: Categorizes talar neck fractures. A Hawkins type 1 fracture is nondisplaced.

6. THE DANGER ZONE

• The Associated Spinal Fracture Trap: Calcaneal fractures are notoriously caused by high-energy axial loading. Up to 10-15% of these patients will have a concomitant, often occult, compression fracture of the spine. Failing to explicitly examine the thoracolumbar spine in a patient with a calcaneus fracture is a classic cognitive trap.
• Avascular Necrosis (AVN) Risk: The talus and navicular bones possess a tenuous, retrograde blood supply. Fractures through the body/neck of these bones routinely sever nutrient arteries, placing the patient at massive risk for AVN and nonunion.
• Missed Lisfranc & Compartment Syndrome: Over-relying on initial plain films is dangerous, as up to 20% of Lisfranc injuries are missed on plain radiographs. Severe midfoot pain with an inability to bear weight demands a CT scan. Furthermore, highly comminuted midfoot/hindfoot fractures and severe crush injuries carry a massive risk for developing acute compartment syndrome.

7. MCQ MASTERCLASS

• Buzzword: "Fleck sign" -> Lisfranc (tarsometatarsal) joint disruption.
• Buzzword: "Decreased Boehler's angle (< 25 degrees)" -> Calcaneus fracture.
• High-Yield Distinction: Differentiate the Jones fracture (a transverse fracture at the base of the 5th metatarsal in "Zone 2" which carries a high risk of nonunion) from a simple avulsion (pseudo-Jones) fracture.
• Exam Distractor: Ordering an MRI for acute foot trauma. Correction: CT is the gold standard modality of choice in the ED for complex bony foot trauma (calcaneus, talus, Lisfranc).
• Procedural Trap: Attempting to reduce an exposed bone fragment back into the wound in an open fracture with intact pulses. Correction: Splint "as it lies" to avoid dragging gross contaminants deep into the sterile tissue beds.

8. THE BOARDROOM SCRIPT

"I am consulting you for a [Age]-year-old [Sex] who sustained a high-energy axial load injury resulting in an intra-articular calcaneus fracture. The lateral radiograph demonstrates a severely flattened Boehler's angle of 10 degrees. The patient has intact dorsalis pedis and posterior tibial pulses, normal digital capillary refill, and no motor/sensory deficits. We have explicitly cleared the thoracolumbar spine. We provided IV analgesia, applied a well-padded posterior splint, elevated the limb, and placed the patient strictly non-weight bearing. A non-contrast CT scan of the foot has been obtained to delineate the articular surface. I would like to review the images with you to arrange for definitive management."