Focused examination of the Achilles tendon including Thompson's test, Silfverskiold test, and assessment of tendinopathy, rupture, and gastrocnemius tightness.
The Achilles tendon examination is fundamental to ankle assessment. Examiners expect you to perform Thompson's test correctly for rupture, use the Silfverskiold test to differentiate gastrocnemius from soleus tightness, and recognize the clinical features of tendinopathy including the "painful arc sign."
High-Yield Exam Summary
Gastrocnemius:
Soleus:
Achilles Tendon:
Clinical Importance of Dual Origin:
Classic Presentation:
Achilles tendon rupture
No plantarflexion of ankle on calf squeeze (foot stays still)
Achilles tendon rupture
Ability to detect true positives
Ability to exclude false positives
Thompson's Test False Negatives: A false negative (apparently normal Thompson's) can occur with:
If clinical suspicion high despite equivocal Thompson's, obtain ultrasound or MRI.
Achilles tendon rupture
Affected ankle falls into neutral or dorsiflexion (normal side stays plantarflexed)
Achilles tendon rupture (loss of tendon tension)
Ability to detect true positives
Ability to exclude false positives
Achilles tendon rupture (continuity test)
Needle does not move with ankle dorsiflexion
Achilles tendon rupture (loss of continuity)
Ability to detect true positives
Ability to exclude false positives
Functional Achilles/calf assessment
Unable to perform single heel raise or significantly weak
Achilles rupture (complete) or significant tendinopathy/weakness
Ability to detect true positives
Ability to exclude false positives
Inspection:
Palpation:
Note Location:
Midsubstance Tendinopathy (Non-insertional):
Insertional Tendinopathy:
Achilles tendinopathy (midsubstance)
Tender swelling moves proximally with dorsiflexion, distally with plantarflexion
Tendinopathy (pathology in tendon itself). If doesn't move = paratenon pathology
Ability to detect true positives
Ability to exclude false positives
Achilles tendinopathy
Tenderness disappears or significantly decreases with dorsiflexion
Achilles tendinopathy (fibers under tension are less tender)
Ability to detect true positives
Ability to exclude false positives
Differentiate gastrocnemius from soleus tightness
Limited dorsiflexion with knee extended that improves with knee flexion = isolated gastrocnemius tightness. Limited in BOTH positions = soleus or combined tightness
Gastrocnemius tightness (most common) vs Soleus tightness. Critical for surgical planning (gastrocnemius release vs TAL)
Ability to detect true positives
Ability to exclude false positives
Silfverskiold Test Interpretation:
| Finding | Knee Extended | Knee Flexed | Diagnosis |
|---|---|---|---|
| Normal | Greater than 10° DF | Greater than 10° DF | No equinus |
| Gastrocnemius tight | Less than 10° DF | Greater than 10° DF | Isolated gastrocnemius |
| Soleus tight | Less than 10° DF | Less than 10° DF | Soleus or combined |
Clinical Relevance:
| condition | presentation | tests | imaging |
|---|---|---|---|
| Achilles Rupture | Sudden pop, unable to push off | Thompson's +, gap palpable | Ultrasound/MRI confirms |
| Achilles Tendinopathy | Gradual onset, activity pain, stiffness | Painful arc +, RLH test + | Ultrasound shows thickening |
| Paratendinopathy | Superficial pain, crepitus | Tenderness doesn't move with ankle | Ultrasound/MRI |
| Retrocalcaneal Bursitis | Posterior heel pain | Squeeze test at insertion | Bursa visible on MRI |
| Haglund's Deformity | Pump bump, shoe irritation | Prominent posterosuperior calcaneus | Lateral X-ray |
| Plantaris Rupture | Sudden calf pain, tennis leg | Thompson's NEGATIVE (Achilles intact) | Ultrasound/MRI |
"45-year-old man felt sudden pop in calf while playing squash 2 days ago. Now unable to walk normally."
| feature | acute | chronic |
|---|---|---|
| Presentation | Clear history, recent injury | Vague history, weeks/months ago |
| Thompson's | Clearly positive | May be equivocal (scar tissue) |
| Gap | Palpable (may be filled with hematoma) | Filled with fibrous tissue |
| Function | Cannot plantarflex/heel raise | Weak plantarflexion possible |
| Treatment | Primary repair or conservative | Often needs reconstruction (FHL transfer, V-Y advancement) |
High-Yield Exam Summary