- Clinical science
The Achilles tendon is the largest tendon in the human body and provides the attachment of the converged soleus and gastrocnemius muscles to the calcaneus. Achilles tendon ruptures often result from indirect trauma related to sports and exercise and primarily affect men between the ages of 30–50 years. Pre-existing degenerative conditions and certain drugs (e.g., local glucocorticoid injections) have been linked with an increased risk of complete or partial Achilles tendon rupture. Patients may experience a sudden onset of sharp pain in the tendon at the back of the ankle, usually accompanied by a popping or snapping sound or sensation. A positive Thompsons test may be followed by an ultrasound or MRI to confirm the Achilles tendon rupture. Both conservative and surgical treatments are recommended. Surgical treatment is associated with a lower risk of Achilles tendon re-rupture. However, complications linked to surgery, such as infection and hemorrhage, must be taken into consideration.
- Peak incidence: 30–50 years
- Sex: ♂ > ♀
- Most common in people that are active in sports or recreational activity
Epidemiological data refers to the US, unless otherwise specified.
- Anatomy of the Achilles tendon
Mechanism of injury
- Indirect trauma from physical activities (e.g., tennis, basketball)
- Rarely, direct trauma or longstanding paratenonitis (possibly with tendinosis)
- Risk factors
- Popping or snapping sound/sensation when the injury occurs
- Sudden, severe pain in the Achilles tendon
- Difficulty mobilizing: loss of plantar flexion power on the affected side
- Deformity: calf swelling; (i.e., hematoma) and/or palpable interruption of the affected Achille's tendon
Thompson test: squeezing the calf (i.e., gastrocnemius muscle) of the patient, in prone position with legs extended
- Normal: results in passive plantar flexion
- Rupture: absent passive plantar flexion
- Equivocal: Place a sphygmomanometer, pumped to 100 mmHg, around the calf. Suspect a tendon rupture if the pressure does not rise to 140 mmHg during dorsiflexion of the foot.
Hyperdorsiflexion sign: the patient sits prone with knees flexed to 90°; both feet are passively dorsiflexed maximally.
- Normal: normal dorsiflexion of the affected leg
- Rupture: excessive dorsiflexion of the affected leg
O'Brien needle test: a needle is inserted 10 cm proximal to the calcaneal insertion of the Achilles tendon; the foot is passively dorsiflexed.
- Normal: the hub of the needle tilts rostrally.
- Rupture: the hub of the needle does not tilt rostrally.
- Thompson test: squeezing the calf (i.e., gastrocnemius muscle) of the patient, in prone position with legs extended
Normal plantar flexion does not rule out a suspected Achille's tendon tear!
Always compare the symptomatic side with the opposite normal side!
- Mainly a clinical diagnosis
- Imaging is indicated to evaluate the extent of the injury and/or to exclude other suspected pathologies.
- Ultrasound (best initial test)
X-ray: mainly to rule out suspected bone fractures
- Nonspecific features of Achilles tendon rupture: soft tissue swelling, damaged pre-Achilles tendon fat pad (Kager's triangle)
- MRI (confirmatory test): only imaging modality that can distinguish between a partial and complete rupture
Both conservative and surgical approaches are recommended, but the indications for conservative vs surgical treatment are controversial.
- Rest, analgesia, serial casting
- Open or percutaneous tendon repair
- Excellent prognosis with early treatment
- Repair of complicated cases (e.g., following re-rupture) has a poorer outcome.