The Achilles tendon is the largest and strongest tendon in the body, connecting the calf muscles to the heel bone and enabling push-off with every step. An Achilles tendon tear can be partial — involving only some of the tendon fibers — or complete (rupture), in which the tendon tears entirely through. It is one of the most significant soft tissue injuries of the lower extremity.
Achilles tendon tears are closely related to other posterior ankle and heel conditions. Patients with chronic tendon pain before a tear often have underlying tendon degeneration, and recovery from rupture requires careful attention to avoid concurrent problems such as plantar fasciitis from altered gait mechanics during rehabilitation.
Causes
- Sudden forceful movement: The most common mechanism is a powerful push-off from the foot — jumping, sprinting, or accelerating rapidly — while the calf contracts forcefully with the foot dorsiflexed. This is the classic "weekend warrior" injury pattern.
- Overuse and repetitive stress: Chronic overloading of the tendon in runners and jumping athletes leads to progressive degenerative changes (tendinosis) that weaken the tendon's structural integrity and predispose it to rupture.
- Age-related degeneration: After age 30–40, the Achilles tendon gradually loses collagen density and tensile strength, making it more vulnerable. Most complete ruptures occur in men aged 30–50 during recreational sports.
- Poor flexibility and tight calf muscles: Reduced ankle dorsiflexion range of motion increases mechanical strain on the tendon during activity.
- Prior tendon injury: A history of Achilles tendinitis or partial tearing weakens the tendon's architecture and raises rupture risk, especially without adequate rehabilitation.
- Biomechanical factors: Flat feet, high arches, or overpronation alter force distribution through the tendon and accelerate degenerative changes.
- Direct trauma: A direct blow to the back of the ankle can lacerate or rupture the tendon, though this mechanism is less common than indirect injury.
- Corticosteroid injections: Repeated injections into or around the Achilles tendon impair collagen synthesis and can significantly weaken tendon tissue, increasing rupture risk.
- Fluoroquinolone antibiotics: Certain antibiotics (ciprofloxacin, levofloxacin) carry an FDA black box warning for Achilles tendon rupture due to their toxic effect on tendon collagen.
Symptoms
- Sudden, severe pain: Most patients describe feeling struck or kicked in the back of the ankle at the moment of injury, followed by sharp, intense pain.
- Audible or palpable pop: A snapping or popping sensation — sometimes heard by bystanders — is a hallmark of complete rupture.
- Swelling and bruising: Swelling develops rapidly around the back of the ankle; bruising spreads toward the heel over the following 24–48 hours.
- Inability to rise onto toes: Loss of plantarflexion strength is the defining functional deficit — patients cannot push off or rise onto the toes of the affected foot.
- Difficulty walking: Weight-bearing is severely impaired with complete rupture; partial tears may allow a painful, altered gait.
- Palpable gap: A defect in the tendon just above the heel can often be felt on examination, particularly within the first hours before swelling obscures it.
- Stiffness and reduced range of motion: Inflammation and protective guarding reduce ankle mobility.
Diagnosis
Clinical diagnosis is often straightforward for complete ruptures. The Thompson test is the key bedside maneuver: with the patient prone and the foot hanging free, squeezing the calf should produce passive plantarflexion. Absence of this response is highly specific for complete Achilles rupture.
MRI is the definitive imaging study for Achilles tendon injuries. It precisely characterizes the tear as partial or complete, measures the gap between torn ends, identifies the degree of tendon degeneration, and evaluates for associated injuries such as retrocalcaneal bursitis or insertional pathology. This information is critical for surgical planning — particularly the gap length and tendon quality — and for predicting healing potential with non-operative management. Ultrasound is a useful adjunct for dynamic assessment but cannot match MRI's tissue characterization.
Classification
Achilles tendon injuries are broadly classified by tear extent and location:
- Partial tear: Some tendon fibers remain intact. May be managed conservatively depending on the percentage of tendon involved and functional deficit.
- Complete rupture: Full-thickness disruption of the tendon, typically 2–6 cm above the calcaneal insertion (the "watershed zone" of poorest blood supply).
- Insertional rupture: Tear at or near the calcaneal attachment, less common, associated with Haglund's deformity or calcific tendinopathy.
- Chronic/neglected rupture: Rupture diagnosed more than 4–6 weeks after injury, with tendon retraction and scarring that complicates repair.
Treatments
Conservative management (appropriate for select patients):
Non-operative treatment with functional rehabilitation in a progressive equinus boot has shown outcomes comparable to surgery in studies of lower-demand patients. The protocol involves early protected weight-bearing, gradual reduction of heel elevation over 8–12 weeks, and structured physical therapy. Re-rupture rates are slightly higher than with surgical repair but the risk of wound complications is eliminated. Best suited for older, less active patients or those with medical comorbidities that increase surgical risk.
Surgical repair (preferred for active patients and athletes):
Primary open or minimally invasive repair reapproximates the torn tendon ends, restoring length and tension. Surgery is generally recommended within 2–3 weeks of injury before tendon retraction and scarring make repair more difficult. Post-operative rehabilitation follows a structured protocol over 4–6 months, with return to sport typically at 6–9 months. Surgical repair offers the lowest re-rupture rate and the best functional outcomes for high-demand patients.
Chronic or neglected rupture:
Ruptures diagnosed late require more complex reconstruction — options include V-Y tendon advancement, flexor hallucis longus (FHL) tendon transfer, or allograft augmentation, depending on the gap size and tissue quality.
Rehabilitation (essential for all patients):
Regardless of operative or non-operative management, structured physical therapy is the foundation of recovery. Early phases focus on range of motion and edema control; later phases progress to calf strengthening, proprioception, and sport-specific training. PRP injections may be used as an adjunct to augment tendon healing in both surgical and non-surgical cases.
Get an MRI to Confirm Your Diagnosis
Before surgical planning or starting treatment, a clear MRI diagnosis ensures the right path forward. First Look MRI offers self-pay Foot and Ankle MRI scans — no doctor's order or insurance required — at our locations in Georgia, Texas, and Colorado.