Talus, Calcaneus, and Midfoot Fractures and Fracture-Dislocations

Introduction

The fractures of the hindfoot and midfoot — talus, calcaneus, navicular, cuboid, cuneiforms, and the tarsometatarsal articulations — together account for a small proportion of orthopedic injuries but carry disproportionate functional consequences when imperfectly managed. The talus and calcaneus form the hindfoot bony skeleton, transmitting load between the leg and the forefoot through complex articulations with limited functional redundancy. The midfoot is the bridge between the relatively rigid hindfoot and the more mobile forefoot, with the Lisfranc joint complex at the tarsometatarsal articulation being the key to midfoot stability. These injuries share several recurring themes: the high-energy mechanism, the tenuous blood supply (particularly to the talus), the limited soft-tissue envelope that complicates surgical access, and the disappointing long-term functional outcomes that follow even optimal management — features that combine to make this region one of the most challenging in orthopedic trauma. This chapter draws on Rockwood and Green’s Fractures in Adults, AO Principles of Fracture Management, Apley & Solomon’s, and Miller’s Review of Orthopaedics.

Talar Anatomy and Blood Supply

The talus is unique among the bones in having approximately 60 percent of its surface covered by articular cartilage, with three major articulations (talocrural with the tibia/fibula superiorly, subtalar with the calcaneus inferiorly, talonavicular with the navicular anteriorly). The bone has no muscular or tendinous attachments. The principal regions are the head, neck, body, and posterior process (with medial and lateral tubercles, and os trigonum as a variable accessory ossification center posterior to the lateral tubercle). The blood supply to the talus is critical to the understanding of its fractures and is principally through three sources: The artery of the tarsal canal (a branch of the posterior tibial artery), which enters between the medial and middle facets and supplies the body of the talus (the principal supply). The artery of the tarsal sinus (anastomosing branches from the dorsalis pedis and peroneal arteries), which enters at the tarsal sinus and supplies the head and neck. The deltoid artery (a branch of the posterior tibial), supplying the medial body. The vascular pattern is such that the talar body is supplied predominantly through the inferior surface via the artery of the tarsal canal, and disruption of this supply through neck fracture displacement produces high rates of avascular necrosis of the body — the central concern in talar neck fractures.

Talar Neck Fractures — The Hawkins Classification

Talar neck fractures account for approximately 50 percent of all talar fractures. The mechanism is forced dorsiflexion with axial load, classically the “aviator’s astragalus” of historical pilot crashes (rudder bar driving up the neck), and today most commonly seen in motor vehicle accidents and falls from height. The Hawkins classification (Lee Hawkins, 1970) organizes talar neck fractures by displacement and associated joint dislocation, with each higher type associated with a substantially higher AVN risk: Type I: Non-displaced talar neck fracture. AVN risk approximately 0 to 13 percent. Type II: Talar neck fracture with subtalar dislocation (ankle joint intact). AVN risk approximately 20 to 50 percent. Type III: Talar neck fracture with subtalar AND ankle joint dislocation. AVN risk approximately 80 to 100 percent. Type IV (Canale and Kelly modification, 1978): Talar neck fracture with subtalar, ankle, AND talonavicular dislocation. AVN risk approaching 100 percent. The increasing AVN risk reflects the progressive disruption of the talar blood supply with each level of dislocation. The implication is that urgent reduction is critical to preserving the chance of avoiding AVN — the displaced fracture-dislocation should be reduced as soon as possible after presentation. The Hawkins Sign The Hawkins sign is a band of subchondral lucency in the talar dome visible at 6 to 8 weeks post-injury, indicating preserved vascularity through disuse osteopenia of the talar body. The presence of the Hawkins sign predicts adequate blood supply and low AVN risk. The absence of the Hawkins sign — particularly when the patient has been bearing weight after fixation — is concerning for AVN, although it does not definitively confirm it. Treatment of Talar Neck Fractures Type I: Treatment is non-operative in a non-weight-bearing cast for 8 to 12 weeks. Operative fixation may be considered for selected patients with displacement under 2 mm and unable to comply with non-weight-bearing protocols, or for patient preference for earlier mobility. Types II, III, and IV: Urgent closed or open reduction and rigid internal fixation. Closed reduction is attempted under appropriate analgesia and muscle relaxation; if unsuccessful, urgent open reduction is performed. The dual approach (anteromedial and anterolateral) is the standard, providing access to the medial and lateral aspects of the talar neck without violating the principal blood supply (avoid extensive posterior dissection that would compromise the artery of the tarsal canal). Cannulated screw fixation with two parallel screws (typically 4.0 or 4.5 mm) provides compression across the fracture.

Anatomical reduction is critical and is assessed both clinically and radiographically; varus malreduction is the most common error and is poorly tolerated. Postoperative management includes non-weight-bearing for 8 to 12 weeks, with progressive weight bearing only after radiographic evidence of healing and the presence of Hawkins sign. The patient must be counseled about the high AVN risk in displaced fractures, the prolonged recovery period, and the substantial likelihood of post-traumatic arthritis even with optimal management. Eventual ankle arthrodesis, subtalar arthrodesis, or tibiotalocalcaneal fusion is required in a substantial minority of patients (10 to 30 percent depending on series).

Other Talar Fractures

Talar Body Fractures Talar body fractures (involving the articular surface of the talar dome) are uncommon and are typically the result of severe axial loading. The fractures may be coronal, sagittal, or comminuted, with the principal concern being the articular involvement and the high rate of AVN. Treatment of displaced fractures is open reduction with cannulated screw fixation, with non-weight-bearing for prolonged periods. Osteochondral Lesions of the Talus Osteochondral lesions of the talus (OLT) — also called osteochondritis dissecans of the talus — are focal injuries to the talar dome cartilage and underlying bone. The classical locations are the posteromedial dome (more common, often associated with prior ankle sprain) and the anterolateral dome (less common, more clearly associated with trauma). The Berndt and Harty classification (1959) organizes the lesions by stage: stage 1 (subchondral bony injury, no displacement), stage 2 (partial separation), stage 3 (complete separation without displacement), stage 4 (displaced loose fragment). Treatment is non-operative (rest, bracing, NSAIDs) for stages 1 and 2 in adults and for all stages in skeletally immature patients (good remodeling and healing potential). Arthroscopic management for stages 3 and 4 includes loose body removal, microfracture for cartilage stimulation, osteochondral autograft transfer (mosaicplasty), or autologous chondrocyte implantation for larger defects. Outcomes are generally good for smaller lesions; larger lesions and lesions in older patients have less predictable outcomes. Lateral Process Fractures (Snowboarder’s Fracture) The lateral process of the talus is fractured in approximately 15 percent of snowboarding ankle injuries (hence “snowboarder’s fracture”) and is often missed on routine ankle radiographs. The mechanism is forced dorsiflexion with eversion. Treatment is non- operative for non-displaced fractures (immobilization for 6 to 8 weeks) and operative for displaced fractures (open reduction with screw fixation or excision of small fragments).

Posterior Process Fractures (Shepherd Fracture) The posterior process of the talus has medial and lateral tubercles separated by the groove for flexor hallucis longus. The lateral tubercle (the larger one) is fractured in forced plantar flexion (the Shepherd fracture) and must be distinguished from the os trigonum (a normal anatomical variant). Acute fractures are treated by immobilization; symptomatic nonunion or chronic posterior impingement (often with FHL tenosynovitis) is treated by excision of the fragment.

Calcaneal Fractures

The calcaneus is the largest tarsal bone and bears the principal weight transmission from the talus to the ground. Calcaneal fractures account for approximately 60 percent of all tarsal fractures and most are produced by fall from height with axial loading through the talus. The energy of the mechanism is substantial and the bilateral injury rate is approximately 10 percent; associated injuries include lumbar spine fractures (10 to 15 percent), other lower extremity injuries, and abdominal injuries. Classification of Intra-Articular Calcaneal Fractures The Sanders CT-based classification (1993) is the standard for intra-articular calcaneal fractures (which constitute the majority — approximately 75 percent — of calcaneal fractures). The classification is based on the appearance of the posterior facet of the calcaneus on a coronal CT image at the level of the widest portion of the posterior facet: Type I: Non-displaced fracture (less than 2 mm displacement) regardless of number of fragments. Type II: Two-part fracture of the posterior facet (subdivided IIA, IIB, IIC by the location of the fracture line). Type III: Three-part fracture of the posterior facet (subdivided IIIAB, IIIAC, IIIBC). Type IV: Four-part highly comminuted fracture. The classification correlates with treatment outcomes — higher Sanders types have progressively worse functional outcomes regardless of treatment. Classification of Extra-Articular Calcaneal Fractures Extra-articular calcaneal fractures (approximately 25 percent) include the anterior process fracture (avulsion by the bifurcate ligament, often missed on radiographs), the tuberosity avulsion (Achilles tendon avulsion), the medial process fracture (avulsion by the abductor hallucis), the sustentaculum tali fracture (with potential involvement of the flexor hallucis longus and the subtalar joint), and the body fracture without articular involvement.

Radiographic Assessment The AP, lateral, and axial (Harris) views of the calcaneus are obtained. Key radiographic measurements on the lateral view: The Böhler’s angle is the angle between the line drawn from the highest point of the anterior process to the highest point of the posterior facet, and the line from the highest point of the posterior facet to the highest point of the tuberosity. The normal angle is 25 to 40 degrees; flattening of the Böhler angle below 20 degrees indicates significant calcaneal compression (depression of the posterior facet). The angle of Gissane (crucial angle) is the angle formed by the inferior aspect of the posterior facet and the dorsal cortical surface of the anterior process. The normal angle is 130 to 145 degrees; increased angle indicates depression of the posterior facet. CT is mandatory for any displaced calcaneal fracture being considered for operative intervention, providing detailed assessment of the posterior facet, the calcaneocuboid joint, and the lateral wall involvement.

Treatment of Calcaneal Fractures The treatment of displaced intra-articular calcaneal fractures has been one of the most actively debated topics in orthopedic trauma. The principal management options are: Non-operative management: Initial immobilization in a posterior splint or boot followed by early protected motion and non-weight-bearing for 8 to 12 weeks. Outcomes are predictably modest, with substantial deformity (lateral wall blow-out, loss of height, subtalar arthritis) and functional impairment. Open reduction and internal fixation (ORIF): Through an extensile lateral approach (the historical standard) or the sinus tarsi approach (the modern minimally invasive alternative). The extensile lateral approach (Letournel/Benirschke) provides excellent visualization of the entire lateral wall and posterior facet but has substantial wound complication rates (5 to 25 percent). The sinus tarsi approach provides direct access to the posterior facet and lateral wall through a smaller incision with substantially lower wound complication rates, and has become the predominant approach in many centers. Primary subtalar fusion: For severely comminuted (Sanders IV) fractures, particularly in patients with comorbidities or poor soft-tissue conditions, primary subtalar fusion may produce better outcomes than ORIF. The HeFT trial (Buckley et al., 2002) and the UK Heel Fracture Trial (Griffin et al., 2014) investigated the operative versus non-operative question. The HeFT trial showed broadly similar functional outcomes between operative and non-operative management in heterogeneous populations; subgroup analyses suggested better outcomes with operative management in females, younger patients, light laborers, and patients with Sanders type II patterns. The UK Heel Fracture Trial found no significant difference in outcomes between operative and non-operative management in a UK population. The current consensus is that operative management is appropriate for displaced Sanders type II and selected

type III fractures in patients with reasonable soft-tissue conditions and functional demands, with non-operative management for Sanders type IV, for patients with poor soft-tissue conditions, and for patients with severe comorbidities. The sinus tarsi approach has substantially reduced the wound complication rate associated with operative management and has changed the operative-versus-conservative balance toward operative management. The complications of calcaneal fracture management include wound complications (the principal historical concern, substantially reduced by the sinus tarsi approach), infection, sural nerve injury (a particular concern with the lateral approach), subtalar arthritis (substantial — 30 to 50 percent develop symptomatic arthritis requiring fusion), chronic lateral wall pain and peroneal tendon impingement (from lateral wall malreduction), and chronic functional limitation.

Subtalar and Other Tarsal Dislocations

Subtalar Dislocation The subtalar dislocation (also called peritalar dislocation) is dislocation of the talus relative to the calcaneus and navicular without fracture of the talus. The classical mechanism is forceful inversion or eversion of the foot. Medial subtalar dislocation (more common, “basketball foot”) is produced by inversion with the foot in plantar flexion. Lateral subtalar dislocation is produced by eversion with the foot in dorsiflexion. Closed reduction is attempted under appropriate analgesia and muscle relaxation, with the knee flexed (to relax the gastrocnemius), traction, and reversal of the displacement maneuver. Closed reduction is successful in 70 to 80 percent of cases. Open reduction is required for irreducible dislocations, with the obstruction typically being a soft-tissue interposition (extensor digitorum brevis tendon, peroneal tendons, posterior tibial tendon for medial dislocation; FHL or talonavicular capsule for lateral). Postoperative management includes immobilization for 4 to 6 weeks followed by progressive range of motion and weight bearing. Outcomes are generally good but with some loss of subtalar motion. Total Talar Dislocation The total talar dislocation — extrusion of the talus from all three articulations — is rare and represents a severe injury. The talus is typically extruded from a wound, becoming exposed. Reimplantation of the talus is generally performed after thorough irrigation, even when the talus is fully extruded, because the alternative (excision and arthrodesis) produces severely compromised function. AVN of the reimplanted talus is essentially universal but can be tolerated for years before requiring fusion.

Midfoot Fractures and Lisfranc Injuries

Anatomy of the Midfoot The midfoot comprises the navicular, cuboid, and three cuneiforms (medial, intermediate, lateral). The Chopart joint (midtarsal joint) is the articulation between the hindfoot (talus, calcaneus) and the midfoot (navicular, cuboid). The Lisfranc joint (tarsometatarsal joint) is the articulation between the midfoot (three cuneiforms and cuboid) and the five metatarsals. The Lisfranc joint complex is stabilized by a system of ligaments, with the dorsal, plantar, and interosseous Lisfranc ligaments (between the medial cuneiform and the base of the second metatarsal) being the principal stabilizers. The plantar Lisfranc ligament is the strongest. The recessed position of the second metatarsal base (“keystone”) between the medial and lateral cuneiforms provides bony stabilization. Disruption of the Lisfranc complex produces the spectrum of Lisfranc injuries from subtle ligamentous disruption to overt fracture-dislocation. Navicular Fractures Navicular fractures include the tuberosity fracture (avulsion of the posterior tibial tendon insertion, often missed and treated as ankle sprain), the dorsal lip fracture (avulsion of the talonavicular capsule, typically from forced plantar flexion), the body fracture (the most concerning pattern, often produced by axial load and frequently associated with cuneiform or other midfoot injuries), and the stress fracture (in athletes, often a high-risk fracture pattern requiring operative management because of the watershed blood supply at the central navicular). Treatment of non-displaced tuberosity and dorsal lip fractures is non-operative in a boot or cast for 4 to 6 weeks. Body fractures with displacement greater than 2 mm or involving the medial column require ORIF, typically with mini-fragment screws or plates. Navicular stress fractures in athletes — particularly the high-risk central body pattern — frequently require percutaneous screw fixation with prolonged non-weight-bearing because of the high nonunion rate with conservative management.

Lisfranc Injuries — Classification and Diagnosis The Lisfranc injury spectrum ranges from subtle ligamentous disruption to overt fracture- dislocation. The Quenu and Küss classification (1909) and the Hardcastle classification (1982) organize the injuries by direction of displacement (homolateral, isolated, divergent), but the more useful clinical distinction is between stable (subtle ligamentous injury without displacement on stress imaging) and unstable (overt displacement or stress-positive instability). The mechanism is typically axial loading with the foot in plantar flexion (the classical “equine rider’s foot caught in the stirrup” mechanism, or the more contemporary dashboard injury or athletic injury). The injury is often missed on initial evaluation because the displacement may be subtle and the patient may be able to bear weight.

Clinical features include midfoot pain, swelling, and ecchymosis; the plantar ecchymosis sign (Ross, 1996) — bruising on the plantar surface of the midfoot — is a specific indicator of Lisfranc injury. Inability to bear weight is common. Imaging includes AP, lateral, and oblique views of the foot, with weight-bearing views being critical for diagnosis (non- weight-bearing views may appear normal, with displacement only evident under load). The key radiographic findings include: Diastasis greater than 2 mm between the first and second metatarsal bases on AP view, indicating disruption of the Lisfranc ligament. The “fleck sign” (Myerson) — a small fleck of bone between the medial cuneiform and the second metatarsal base, representing avulsion of the Lisfranc ligament. Loss of alignment between the medial border of the second metatarsal and the medial border of the middle cuneiform on AP view, or between the medial border of the fourth metatarsal and the medial border of the cuboid on oblique view. CT with weight-bearing if possible is increasingly used for definitive characterization, and MRI is used when ligamentous injury is suspected without bony displacement. Treatment of Lisfranc Injuries The stable Lisfranc injury (subtle ligamentous injury without displacement on stress imaging) may be treated non-operatively in a boot or cast for 6 to 8 weeks with non-weight bearing, but this represents a small minority of cases. The unstable Lisfranc injury requires anatomical reduction and stabilization, which is the principal determinant of long-term outcome. Multiple operative techniques exist: Open reduction and internal fixation with transarticular screws across the Lisfranc joints (the historical standard). The screws are typically 3.5 or 4.0 mm cortical screws crossing from the medial cuneiform into the second metatarsal base, the medial cuneiform into the middle cuneiform, and other articulations as needed. Hardware removal is typically performed at 3 to 6 months to permit return of normal joint motion. The technique produces good outcomes in well-reduced injuries. Bridge plating with dorsal plates spanning the Lisfranc joint has gained popularity as an alternative to transarticular screws, with theoretical advantages of joint preservation but similar overall outcomes. Primary arthrodesis of the Lisfranc joints (typically the medial three columns — medial, middle, and lateral cuneiform-metatarsal joints) has been proposed for purely ligamentous Lisfranc injuries on the basis that the joints are unlikely to regain normal function and that fusion produces more predictable outcomes. The Ly and Coetzee trial (2006) demonstrated better short-term outcomes with primary fusion compared with ORIF for purely ligamentous Lisfranc injuries; subsequent studies have produced more mixed results, with the current consensus being that primary fusion is appropriate for purely ligamentous injuries with severe instability, while ORIF remains the standard for fracture- dislocations and for bony injuries with reconstructible anatomy.

The outcomes of Lisfranc injury management are generally less than perfect, with most patients retaining some level of midfoot pain or functional limitation. The principal long- term complication is post-traumatic arthritis, requiring later arthrodesis in 10 to 30 percent of patients.

Cuboid and Cuneiform Fractures

Cuboid fractures are uncommon but may be produced by direct trauma or by nutcracker mechanism (compression of the cuboid between the calcaneus and the fourth and fifth metatarsals during forced foot abduction). The fracture may produce lateral column shortening, with secondary cavovarus deformity. Treatment of displaced cuboid fractures with lateral column shortening requires distraction and bone grafting through a lateral approach, often with external fixator or temporary K-wire fixation across the calcaneocuboid joint to maintain length. Cuneiform fractures are uncommon in isolation and are usually part of broader midfoot injuries. Treatment depends on the associated injuries; isolated displaced cuneiform fractures are typically fixed with screws or K-wires.

Metatarsal Fractures

Metatarsal fractures are common and represent a separate category in many discussions. They are not addressed here in detail (typically discussed in the foot and ankle subspecialty literature), but several patterns deserve brief mention: The fifth metatarsal base fracture has three classical patterns: the tuberosity avulsion (peroneus brevis avulsion, the “dancer’s fracture” — heals well with conservative management), the Jones fracture (metaphyseal-diaphyseal junction, high-risk fracture with nonunion rate of 25 to 30 percent with conservative management, frequently treated by percutaneous screw fixation in athletes), and the proximal diaphyseal stress fracture (similar to Jones in management). Lesser metatarsal stress fractures (“march fractures”) are common in military recruits and runners, typically affecting the second metatarsal. Treatment is relative rest and protected weight bearing for 4 to 6 weeks. Metatarsal shaft and neck fractures typically heal well with cast or boot immobilization. Operative fixation is reserved for severely displaced fractures, multiple metatarsal fractures, or open injuries.

Summary and Take-Home Points

The talar neck fracture is the central injury of the talus, with the Hawkins classification (I non-displaced, II with subtalar dislocation, III with subtalar and ankle dislocation, IV with all three joint dislocations) predicting both the surgical urgency and the AVN risk (rising from 0 percent in Hawkins I to nearly 100 percent in Hawkins IV). Urgent closed or open reduction of displaced fractures is essential, with anatomical reduction and rigid cannulated screw fixation through a dual anteromedial-anterolateral approach. The

Hawkins sign at 6 to 8 weeks predicts preserved talar vascularity; its absence is concerning for AVN. The calcaneal fracture is classified by the Sanders CT-based system for intra-articular fractures (types I-IV by posterior facet morphology). The active debate between operative and non-operative management has settled toward operative management for Sanders II and selected III in patients with reasonable soft tissues and functional demands, with the sinus tarsi approach replacing the historical extensile lateral approach in many centers because of substantially lower wound complication rates. Böhler’s angle (normal 25-40 degrees) and the angle of Gissane (normal 130-145 degrees) are key radiographic measurements. The Lisfranc injury requires recognition based on the plantar ecchymosis sign, weight- bearing radiographs showing diastasis greater than 2 mm, the “fleck sign,” and CT confirmation. Treatment of unstable Lisfranc injuries is anatomical reduction with transarticular screw fixation or bridge plating, with primary arthrodesis being an alternative for purely ligamentous patterns. The navicular fracture, particularly the central body stress fracture, often requires operative management because of the watershed blood supply and the high nonunion rate. The cuboid fracture with lateral column shortening (nutcracker mechanism) requires distraction and bone grafting. Subtalar dislocations are typically closed reducible (70 to 80 percent), with open reduction reserved for irreducible patterns with soft-tissue interposition. The outcomes of hindfoot and midfoot trauma are generally less predictable than for proximal lower extremity fractures, with substantial rates of post-traumatic arthritis, residual pain, and functional limitation even with optimal management. The chapter that follows turns to soft-tissue injuries — muscle, tendon, and peripheral nerve injuries — that complete the trauma section of this compendium.