What are the symptoms of an Achilles tendon tear?

Symptoms of Achilles Tendon Tear

The key symptoms of an Achilles tendon tear include sudden onset of pain in the posterior heel area, often accompanied by an audible "pop" or "snap" sensation, swelling, bruising, and inability to bear weight or perform plantar flexion of the foot. 1

Clinical Presentation

• Patients typically experience acute, sharp pain in the posterior ankle region at the moment of injury, often described as feeling like being "kicked" or "shot" in the back of the ankle 1
• An audible "pop" or "snap" sound may be heard or felt at the time of injury 1
• Significant swelling and bruising (hematoma) develop rapidly in the posterior ankle area 1
• Patients demonstrate inability or significant difficulty with weight-bearing on the affected limb 1
• Weakness or complete inability to perform plantar flexion (pointing the foot downward) is present 1

Physical Examination Findings

• Palpable gap or defect in the Achilles tendon, typically 2-6 cm proximal to its insertion on the calcaneus 1
• Positive Thompson test (lack of plantar flexion when the calf is squeezed while the patient is prone with feet hanging off the examination table) 1
• Increased passive dorsiflexion of the affected ankle compared to the uninjured side 1
• Tenderness along the posterior ankle, particularly at the site of the tear 1
• Visible deformity or asymmetry when comparing to the uninjured side 1

Distinguishing Complete vs. Partial Tears

• Complete tears typically present with:

  • Inability to stand on tiptoes on the affected side 1
  • Palpable gap in the tendon 1
  • Strongly positive Thompson test 1

• Partial tears may present with:

  • Less pronounced weakness in plantar flexion 1
  • Ability to perform a single heel raise, though with pain 1
  • Minimal or no palpable defect in the tendon 1

Common Pitfalls in Diagnosis

• Up to 25% of acute Achilles tendon ruptures are initially misdiagnosed, leading to chronic injuries that are more difficult to treat 2
• Achilles tendon ruptures may be mistaken for ankle sprains, especially if the Thompson test is not performed 1
• Examination within the first 48 hours may be limited by excessive swelling and pain, making reexamination after 3-5 days important for accurate diagnosis 1
• Patients with partial tears may still be able to plantarflex against resistance, leading to missed diagnosis of significant tendon injury 1

Diagnostic Imaging

• Ultrasound is highly effective for diagnosing Achilles tendon tears, showing tendon discontinuity, thickening, and heterogeneous echogenicity 1
• MRI is the gold standard imaging technique, with high sensitivity (95%) and specificity (95%) for detecting complete tears, partial tears, and chronic degenerative changes 1
• Plain radiography has limited value but may show soft tissue swelling, calcific tendinosis, or calcaneal avulsion fractures 1

Risk Factors and Mechanism of Injury

• Most common in middle-aged men who occasionally participate in sports 2
• Typically occurs during activities requiring jumping, running, or quick turns 3
• Often involves sudden dorsiflexion of a plantarflexed foot or forceful push-off with the weight-bearing foot 4
• Pre-existing degenerative changes in the tendon are often present before rupture, even in patients without previous symptoms 3

Early recognition of these symptoms is crucial for proper management, as delayed diagnosis can lead to more complicated treatment and poorer outcomes 2, 1.