Calcaneal Tuberosity Fractures

Calcaneal tuberosity fractures are rare but important injuries involving the posterior tuberosity of the calcaneus, which serves as the insertion site for the Achilles tendon. These fractures represent avulsion injuries and require ORIF if displaced to prevent loss of plantarflexion power and equinus contracture.

Definition

Calcaneal tuberosity fracture: Fracture of the posterior tuberosity of the calcaneus, which:

• Serves as insertion site for Achilles tendon
• Represents avulsion injury
• Causes loss of plantarflexion power

Achilles tendon insertion:

• Location: Posterior tuberosity of calcaneus
• Function: Plantarflexion and push-off
• Avulsion: Excessive tension causes avulsion with bone fragment

Epidemiology

• Incidence: Rare - approximately 1.3-2.7% of all calcaneal fractures (Lee 2012 found 20/764 = 2.6%)
• Age: Typically older adults; Carnero-Martin series mean age 57 years
• Gender: Female predominance (around 62% in Carnero-Martin), reflecting post-menopausal osteoporosis
• Comorbidity: Diabetes in roughly 1 in 5 (19% in Carnero-Martin); many are insufficiency or Charcot-related avulsions
• Mechanism: 71% low-energy (trip/fall) in Carnero-Martin; less commonly direct blow (Lee type II) or high-energy
• Associated injuries: Ipsilateral foot/ankle fractures; assess the whole hindfoot

Calcaneal Tuberosity Anatomy

Posterior tuberosity of calcaneus:

• Location: Posterior aspect of calcaneus
• Function: Insertion site for Achilles tendon
• Size: Large, prominent posterior projection
• Blood supply: Branches from posterior tibial artery

Achilles tendon insertion:

• Location: Posterior tuberosity of calcaneus
• Function: Plantarflexion and push-off
• Width: 1.5-2cm at insertion
• Avulsion: Excessive tension causes avulsion with bone fragment

Sural nerve:

• Location: 1-2cm posterior to lateral malleolus
• Function: Sensory to lateral foot
• Risk: At risk in posterior approach

Pathophysiology

Injury mechanism:

• Sudden plantarflexion: Eccentric contraction of gastrocnemius-soleus
• Excessive tension: Achilles tendon experiences excessive tension
• Avulsion: Tendon avulses from tuberosity with bone fragment
• Low-energy / insufficiency: Often in osteoporotic or diabetic (Charcot) bone where minor force avulses a weakened tuberosity

Why displacement matters:

• Loss of function: Displacement causes loss of plantarflexion power
• Equinus contracture: Proximal migration causes equinus
• Push-off weakness: Inability to push off affects gait

Why ORIF required:

• Restore function: Anatomic reduction restores plantarflexion
• Prevent contracture: Prevents equinus contracture
• Early motion: Stable fixation allows early motion

History

Symptoms:

• Posterior heel pain: Pain in posterior heel
• Loss of plantarflexion: Unable to push off
• Swelling: Localised to posterior heel
• Difficulty walking: Pain with weight bearing

Mechanism:

• Sudden plantarflexion
• Fall
• Direct trauma to heel

Physical Examination

Inspection:

• Swelling in posterior heel
• Ecchymosis (may be delayed)
• Deformity (proximal migration of fragment)

Palpation:

• Tenderness over calcaneal tuberosity
• Gap at fracture site (if displaced)
• Achilles tendon continuity (may be disrupted)

Range of Motion:

• Loss of active plantarflexion
• Passive plantarflexion may be limited
• Equinus deformity (if displaced)

Special tests:

• Active plantarflexion: Unable to perform (loss of power)
• Thompson test: May be positive (Achilles dysfunction)
• Straight leg raise: May be limited (pain)

Differential Diagnosis

Sural Nerve Injury

5-10% incidence:

• Cause: Posterior approach, nerve at risk
• Prevention: Identify and protect sural nerve (1-2cm posterior to lateral malleolus)
• Management: Neuroma excision if symptomatic

Equinus Contracture

10-15% incidence (if untreated):

• Cause: Proximal migration of fragment, delayed treatment
• Prevention: Early ORIF, adequate fixation
• Management: Stretching, serial casting, or surgical release

Immediate Postoperative

• Immobilisation: Short leg cast or boot
• Weight bearing: Non-weight bearing initially (2-4 weeks)
• ROM: Ankle ROM exercises early (if stable fixation)
• PT: Plantarflexion strengthening

Rehabilitation Protocol

Weeks 0-2:

• Short leg cast, non-weight bearing
• Elevation to reduce swelling
• Ankle ROM exercises (if stable)

Weeks 2-4:

• Transition to walking boot
• Progressive weight bearing (if stable)
• Plantarflexion strengthening

Weeks 4-8:

• Full weight bearing
• Progressive activity
• Return to sport (3-4 months)

Overall Outcomes

ORIF (tension band wiring):

• Success rate: 80-90% (union, pain relief)
• Functional outcomes: 75-85% return to pre-injury level
• Plantarflexion: 80-90% restore normal strength

ORIF (screw fixation):

• Success rate: 75-85% (union, pain relief)
• Functional outcomes: 70-80% return to pre-injury level
• Plantarflexion: 75-85% restore normal strength

Conservative (non-displaced, rare):

• Success rate: 85-90% (union, pain relief)
• Functional outcomes: 80-85% return to pre-injury level
• Plantarflexion: 85-90% restore normal strength

Long-Term Prognosis

Plantarflexion recovery:

• With proper treatment: 80-90% restore normal strength
• Without treatment: 20-30% develop permanent weakness
• Risk factors: Displacement, delayed treatment, inadequate fixation

The evidence base for these fractures is limited to small retrospective series and case reports, so several questions remain genuinely unsettled:

• Which classification to use - Morphological schemes (Lee, Beavis) describe the fracture but Carnero-Martin showed they do not predict outcome. A displacement-based prognostic classification is proposed but not yet validated in larger cohorts.
• Fixation construct - Tension band wiring, large cannulated lag screws, plate fixation and suture anchors are all described; no comparative trial establishes superiority. Choice is driven by fragment size, bone quality and surgeon preference rather than high-level evidence.
• Fragment excision versus fixation - In small fragments or very poor (neuropathic/osteoporotic) bone, some advocate excision with Achilles reattachment plus gastrocnemius recession rather than struggling to fix unfixable bone.
• Urgency threshold - There is consensus that threatened skin demands urgent reduction, but the exact displacement or skin-tenting threshold that mandates emergency surgery is not precisely defined.
• Role of gastrocnemius lengthening - Whether to routinely address gastroc-soleus tightness at index surgery to reduce re-displacement is advocated by some (Banerjee) but not standardised.
• Hardware removal - Tension band wires are frequently prominent in this subcutaneous location; rates and timing of elective removal vary widely.

Global Epidemiology

• Rare injury: roughly 1.3-2.7% of all calcaneal fractures across published series
• Bimodal pattern: low-energy insufficiency avulsions in elderly osteoporotic women (Lee type I) and higher-energy or direct-blow patterns in younger men
• Strong association with osteoporosis and diabetes/Charcot neuroarthropathy; diabetic prevalence around 19% in surgical series

Society Guidance and Practice Points (Side by Side)

Registry and Resource-Setting Notes

• No arthroplasty registry applies; evidence is from institutional series, so practice variation is wide and surgeon-dependent.
• High-resource settings: ready access to CT/MRI, multiple implant options (tension band, cannulated screws, suture anchors) and combined ortho-plastic cover for threatened skin.
• Limited-resource settings: reliance on radiographs alone, K-wire and cerclage-based tension band constructs (low cost, effective), and a lower threshold for fragment excision and Achilles reattachment when implants or soft-tissue cover are unavailable. Urgent reduction to save skin remains universal and equipment-independent.