Calcaneal Fractures — Sanders & Essex-Lopresti

Overview & Anatomy

Calcaneal fractures are the most common tarsal fractures, accounting for approximately 60% of all tarsal bone injuries. The majority are intra-articular, involving the posterior facet of the subtalar joint, and result from axial loading — typically a fall from height. The outcomes of these injuries are notoriously variable, and the management remains one of the most debated areas in foot and ankle surgery. The Sanders CT-based classification and the Essex-Lopresti plain radiograph classification are the two foundational systems that guide diagnosis, operative decision-making, and prognosis.

Mechanism: axial compression from falls from height (the calcaneus impacts the ground and the talus is driven downward into it); the lateral process of the talus acts like a wedge splitting the calcaneus; the primary fracture line runs obliquely from the posterolateral to the anteromedial cortex — dividing the calcaneus into an anteromedial fragment and a posterolateral fragment; secondary fracture lines then further divide the posterior facet
Key anatomical parameters assessed on plain X-ray: (1) Böhler`s angle (tuber-joint angle) — the angle formed between a line from the highest point of the posterior facet to the highest point of the tuberosity, and a line from the highest point of the posterior facet to the highest point of the anterior process; normal = 20–40°; depressed calcaneal fracture = reduced or negative Böhler`s angle; Böhler`s angle <0° = severe depression; restoration of Böhler`s angle to >15° correlates with improved outcomes; (2) Gissane`s angle (critical angle) — the angle at the `crucial angle` of the calcaneus where the posterior facet meets the anterior process; normal = 120–145°; increased in calcaneal fractures as the posterior facet is depressed and the critical angle opens up
Associated injuries: bilateral calcaneal fractures (both feet landing simultaneously — ~10% of falls from height); lumbar spine compression fractures (axial load transmitted up the limb — always check the spine clinically and radiologically in patients with bilateral calcaneal fractures); compartment syndrome of the foot (acute risk in severe calcaneal fractures — measure compartment pressures in obtunded/unconscious patients); soft tissue injury (the lateral heel skin is particularly at risk — the calcaneus subluxes laterally, blowing out the lateral cortex and stretching the thin lateral skin)

Essex-Lopresti Classification (Plain Radiograph)

Type	Description	Lateral X-Ray Finding	Clinical Significance
Joint depression type	The secondary fracture line exits posterior to the posterior facet of the subtalar joint; the posterior facet is depressed as a separate fragment (the `joint depression fragment`) that sinks into the calcaneal body while the posterior tuberosity remains relatively elevated	Characteristic `double density` shadow on lateral X-ray — the normal posterior facet and the depressed fragment create overlapping shadows; Böhler`s angle is markedly reduced or negative; posterior facet fragment visible as a separate depressed piece	More common type (~75%); more amenable to surgical reconstruction — the posterior facet fragment can be elevated and held with fixation; restoration of the articular surface is the surgical goal
Tongue type	The secondary fracture line exits through the posterior tuberosity, creating a large `tongue` fragment that includes both the posterior facet AND the tuberosity as one piece; the tongue fragment is displaced posterosuperiorly by the Achilles tendon pull; the subtalar joint is involved as part of the tongue fragment	The tongue fragment is visible on the lateral view displaced posterosuperiorly; the Achilles tendon maintains its insertion on the tongue fragment and pulls it upward; skin at the posterior heel can be tent-stretched by the upwardly displaced tongue fragment — a skin emergency requiring urgent reduction	The tongue-type fracture with posterior skin tenting = orthopaedic emergency; the skin over the posterior heel is under extreme tension from the displaced tongue fragment; if not urgently reduced and stabilised, the skin will necrose — leading to a catastrophic open wound over the heel that is extremely difficult to manage; percutaneous reduction (Essex-Lopresti manoeuvre — a Schanz pin in the posterior tuberosity used as a joystick to reduce the tongue fragment and decompress the skin) is performed urgently

Sanders CT Classification (Posterior Facet)

The Sanders classification is based on a coronal CT scan through the widest part of the posterior facet of the subtalar joint. The posterior facet is divided into three columns (A, B, C) by two lines on the coronal CT — A is the lateral column, B is the middle column, C is the medial column. The classification describes the number and location of fracture lines within the posterior facet.

Sanders Type	Description	Prognosis	Treatment
Type I — Undisplaced	All fractures of the posterior facet regardless of the number of fracture lines are undisplaced (<2 mm displacement); the posterior facet is intact articular surface	Excellent prognosis; low risk of post-traumatic subtalar arthritis	Non-operative — cast or removable boot; protected weight-bearing for 6–8 weeks; functional outcomes very good
Type II — 2 fragments (1 fracture line)	One fracture line divides the posterior facet into two fragments; sub-classified by position of the fracture line: IIA (lateral column — line between A and B), IIB (middle — line between B and C), IIC (medial — line through C); 2-part posterior facet fracture; moderate displacement	Good prognosis with surgical reduction and fixation; ORIF achieves good restoration of the posterior facet; satisfactory long-term outcomes reported	ORIF (open reduction internal fixation) — standard extensile lateral approach or sinus tarsi approach; elevation of the posterior facet fragment, lag screw fixation of the posterior facet, lateral wall reconstruction with calcaneal plate; good results with early surgery (within 7–14 days of soft tissue optimisation)
Type III — 3 fragments (2 fracture lines)	Two fracture lines divide the posterior facet into three fragments; sub-classified as IIIAB, IIIAC, IIIBC depending on which columns are involved; the middle fragment is typically depressed and impacted; the most common intraarticular calcaneal fracture type	Moderate-to-poor prognosis; significant post-traumatic subtalar arthritis risk; outcomes of surgical treatment are better than non-operative but variable; 20–35% eventually require subtalar fusion	ORIF if patient is suitable and soft tissues allow; technically demanding; the depressed middle fragment must be elevated and supported with bone graft or substitute; meticulous soft tissue handling essential; alternatively, primary subtalar fusion at the time of initial surgery (for very comminuted type III in high-demand elderly patients)
Type IV — ≥4 fragments (≥3 fracture lines)	Highly comminuted posterior facet with 3 or more fracture lines; the posterior facet is shattered into 4 or more fragments; anatomical reconstruction is technically impossible or impractical	Poor prognosis regardless of treatment; very high rate of post-traumatic subtalar arthritis; the posterior facet articular surface cannot be anatomically restored	Primary subtalar arthrodesis (primary fusion at the time of calcaneal reconstruction — restores calcaneal morphology AND fuses the subtalar joint); non-operative management in poor surgical candidates; ORIF rarely attempted for Type IV as reconstruction is not feasible

Surgical Management

ORIF timing — the `wrinkle sign`: surgery for displaced intra-articular calcaneal fractures must be delayed until the acute soft tissue swelling has resolved sufficiently; the extensile lateral approach requires a full-thickness flap elevated off the lateral wall of the calcaneus — if performed in acutely swollen tissue, wound dehiscence rates are catastrophic (up to 25–30%); surgery is deferred until the `wrinkle sign` is positive — the appearance of skin wrinkles over the lateral heel when the foot is dorsiflexed, indicating that the acute oedema has resolved; this typically takes 7–14 days; in the meantime the foot is elevated, ice is applied, and a temporary backslab is applied; the `wrinkle sign` is a clinical landmark for surgical timing
Extensile lateral approach: the gold standard open approach for ORIF; a full-thickness flap is elevated as a single layer off the lateral wall from the heel tuberosity to the calcaneocuboid joint and upward to expose the posterior facet; the peroneal tendons, sural nerve, and lateral wall fragments are reflected in the flap; the posterior facet is elevated (under direct vision), the fracture reduced, and a lag screw placed across the posterior facet; the lateral wall is then reconstructed with a low-profile calcaneal plate; meticulous single-layer closure; wound problems remain the Achilles heel of this approach
Minimally invasive / sinus tarsi approach: increasingly popular alternative to the extensile lateral approach; a small incision over the sinus tarsi allows percutaneous or semi-open reduction and fixation of the posterior facet under fluoroscopic or arthroscopic guidance; significantly lower wound complication rates; comparable functional outcomes to extensile lateral approach for Sanders II and III fractures in multiple RCTs (STARR trial); preferred by many surgeons for Sanders II and selected III fractures in high-risk patients (smokers, diabetics, peripheral vascular disease)
Non-operative management: appropriate for Sanders I (undisplaced), non-displaced tongue-type without skin compromise, medically unfit patients, Sanders IV in low-demand elderly, bilateral fractures where staged surgery is required; the UK SURFER trial (Agren et al. / Bridgman et al.) and the landmark Netherlands ORIF vs non-operative RCT (Buckley et al.) showed no significant difference between ORIF and non-operative treatment for all displaced intra-articular calcaneal fractures in intention-to-treat analysis — but subgroup analysis (Sanders II, younger patients, lighter workers, anatomical reduction) consistently shows ORIF superior

Complications

Wound complications: the most dreaded complication of extensile lateral ORIF; wound dehiscence and deep infection rates of 5–25% in high-risk patients; risk factors: smoking (most important — smoking cessation for at least 4 weeks before surgery mandatory), diabetes, peripheral vascular disease, obesity, steroid use, severe soft tissue injury, early surgery before wrinkle sign; deep infections over exposed hardware are catastrophic and may require debridement, hardware removal, and free flap reconstruction
Post-traumatic subtalar arthritis: the most common long-term complication; incidence proportional to Sanders type (Type I ~5%; Type II ~15%; Type III ~25–35%; Type IV ~50–70%); manifests as subtalar pain, stiffness, and disability; managed initially with insoles, footwear modification, activity modification, and injections; definitive treatment: subtalar arthrodesis (fusion) — reliable pain relief but reduces hindfoot motion; most patients with Sanders III/IV fractures will eventually require subtalar fusion
Peroneal tendon impingement: lateral wall blow-out creates a lateral bony spike that impinges on the peroneal tendons in the peroneal groove; causes lateral ankle pain and peroneal tendinopathy; managed by lateral wall exostectomy (removal of the bony prominence)
Malunion: widening of the calcaneus, loss of height, varus heel alignment; causes subtalar pain, peroneal impingement, and shoe-fitting difficulties; corrective osteotomy or subtalar fusion for symptomatic malunion

Exam Pearls

Böhler`s angle: normal 20–40°; reduced/negative in calcaneal fracture = significant depression; restoration >15° correlates with improved outcomes; measured on lateral plain X-ray
Essex-Lopresti: joint depression type (~75%) — posterior facet depressed as separate fragment; tongue type (~25%) — tuberosity + posterior facet displaced as one piece by Achilles pull; tongue type with posterior skin tenting = orthopaedic emergency — urgent percutaneous reduction to prevent skin necrosis
Sanders classification: based on coronal CT through widest posterior facet; Type I (undisplaced — non-op); Type II (2 parts — ORIF, good prognosis); Type III (3 parts — ORIF, variable); Type IV (≥4 parts — primary subtalar fusion or non-op, poor prognosis)
Wrinkle sign: surgical timing landmark for extensile lateral ORIF; wrinkles appear over the lateral heel on dorsiflexion when oedema has resolved (7–14 days); operating before wrinkle sign = dramatically increased wound complication rate
Wound complications: the chief risk of extensile lateral approach; smoking is the single biggest risk factor (cessation for 4 weeks mandatory); sinus tarsi approach significantly reduces wound complications and is increasingly preferred for Sanders II/III
Associated injuries: always image the lumbar spine in bilateral calcaneal fractures (axial load transmitted up); compartment syndrome of the foot is a risk — 9 compartments in the foot; fasciotomy through dorsal and medial incisions
Post-traumatic subtalar arthritis: most common long-term complication; Sanders III/IV → 25–70% rate; definitive treatment = subtalar arthrodesis; good pain relief but stiff hindfoot
RCT evidence: SURFER/Buckley trials — no significant difference between ORIF and non-operative treatment in intent-to-treat analysis overall; BUT subgroup analysis consistently shows ORIF superior in Sanders II, younger patients, lighter workers, anatomical reductions; Sanders I = non-operative; Sanders IV = primary fusion or non-op

Calcaneal Fractures — Sanders & Essex-Lopresti

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