Achilles Tendon Rupture: Causes, Symptoms, and Treatment

What Is the Achilles Tendon?

The Achilles tendon is the largest and strongest tendon in the human body. It connects the two main calf muscles — the gastrocnemius and soleus — to the calcaneus (heel bone). This tendon transmits the force of calf contraction to the foot, enabling plantarflexion (pointing the foot down) — the motion required for walking, running, jumping, and climbing stairs.

The Achilles tendon has poor blood supply in its mid-portion (approximately 2–6 cm above the heel) — the zone where most ruptures occur. This poor vascularity is thought to contribute to degenerative changes that predispose the tendon to rupture.

How Rupture Occurs

Achilles rupture typically occurs with a sudden forceful plantarflexion of the foot — often while:

Pushing off to sprint or jump (recreational sports, "weekend warriors")
Making an unexpected step (stepping off a curb)
Falling from a height with dorsiflexed foot

The classic patient is a 30–50 year old male ("weekend warrior") who suddenly resumes intense activity after a period of inactivity. Females are affected less often (male:female ratio approximately 5:1).

Predisposing factors:

Prior Achilles tendinopathy (degenerative tendon disease)
Fluoroquinolone antibiotics (ciprofloxacin, levofloxacin) — significantly increase tendon rupture risk; avoid intense exercise while on these medications
Corticosteroid injections into the tendon (should never be injected directly into the Achilles)
Age (degenerative changes with aging)
Obesity

Symptoms

At the moment of rupture:

"Someone kicked me" sensation in the back of the leg — often the classic description
Audible "pop" or "crack" heard by patient or bystanders
Immediate pain in the calf/heel area (may subside quickly)
Sudden difficulty walking, particularly inability to push off

Subsequent findings:

Palpable gap: A defect can often be felt in the tendon approximately 2–5 cm above the heel
Significant swelling and bruising over the posterior heel and calf
Weakness with plantarflexion — inability to stand on tip-toe on the affected foot

Diagnosis

Thompson (Simmonds) test: Patient lies face-down; squeezing the calf does NOT produce foot plantarflexion — this confirms complete Achilles tendon rupture. A very reliable bedside test.

Ultrasound: Dynamic real-time imaging; confirms rupture and assesses gap size and tendon apposition when the foot is plantarflexed (determines if conservative treatment is feasible)

MRI: Gold standard for detailed assessment; used when diagnosis is uncertain or for surgical planning

Treatment

Both surgical and non-surgical treatment of Achilles rupture are effective and produce comparable outcomes in modern studies. Treatment choice depends on patient age, activity level, and individual factors.

Non-Surgical Treatment

Modern non-surgical management uses functional rehabilitation with early weight bearing rather than prolonged casting:

Immediate immobilization in equinus (plantarflexed) position — walking boot
Gradual dorsiflexion restoration over 8–10 weeks
Progressive weight bearing
Physical therapy beginning early

Non-surgical outcomes: Comparable re-rupture rate (5%) and functional outcomes to surgery in several large studies. Appropriate for older patients, lower-demand individuals, or those with comorbidities increasing surgical risk.

Surgical Treatment (Achilles Tendon Repair)

Direct surgical repair of the tendon ends through a posterior incision:

Lower re-rupture rate in some series
May allow faster functional return for competitive athletes
Carries surgical risks: wound complications, nerve injury (sural nerve), DVT

Minimally invasive percutaneous repair techniques offer an intermediate approach with less wound complication risk.

Recovery Timeline

Whether treated surgically or non-surgically:

Full weight bearing: 8–12 weeks (progressive)
Return to running: 4–6 months
Return to sport: 9–12 months
Full recovery: 12–18 months (the Achilles tendon is slow to fully heal)