The Achilles tendon is the largest and strongest tendon in the human body, but it can also be vulnerable to overuse. The tendons’ structural prowess is relentlessly confronted by functional demands that can be up to 12 ½ times body weight while running.
The Achilles tendon may be acutely strained or ruptured as the result of an excessive stretch or eccentric force. This happens during the “mid-stance” phase of gait. Strains occur when collagen fibers are stretched by more than 4%. Ruptures occur when stretch exceeds 8%. The Achilles acts as a spring to transfer force between the ground and the body.
Unlike acute injuries that cause inflammation, tendinopathy is characterized by repeated overloading, microtearing, failed healing, and subsequent tendon degeneration. The process begins with collagen fiber disruption and ends in a disorganized healing process that fails to regenerate a “normal” tendon. Failed healing is blamed on a hyperplastic, but ineffective, microvascular system.
Two-thirds of all Achilles tendon injuries involve athletes. Runners are up to 10 times more likely to suffer Achilles tendon injuries compared to age-matched controls.The estimated incidence of Achilles tendinopathy is: running sports, 53%; soccer, 11%; dance, 9%; gymnastics, 5%; racquet sports, 2%; football, 1%.
Extrinsic risk factors for Achilles injury include improper warm up, overtraining, cold weather training, running on hard surfaces, excessive stair or hill climbing, improper arch support/ footwear, poor conditioning and abruptly returning to activity after a period of inactivity. Wearing high-heeled shoes may. Intrinsic factors include, prior lower limb fracture, hyperpronation, pes planus, cavus foot, gastrocnemius/soleus inflexibility or weakness, limited ankle dorsiflexion, and limited subtalar motion. Systemic risk factors include diabetes, hypertension, inflammatory arthropathy, gout, and the use of corticosteroids or quinolones (broad spectrum antibiotics).Obese patients carry a 4-6 fold higher risk of developing Achilles tendinopathy.
Patients may present with symptoms from an acute strain or a more gradual onset repetitive irritation. Complaints include pain or tenderness in the tendon or heel that intensifies with activity, especially walking or running. Patients may report difficulty when attempting to stand on their toes or walking steps- particularly down stairs. Morning pain and stiffness are common. Patients may report warmth and swelling that increases throughout the day, related to activity.
Conservative treatment is the mainstay for Achilles tendinopathy, and surgery is rarely necessary. “Traditional” treatment plans based solely on rest, therapy modalities, orthotics, and NSAIDs have failed to demonstrate benefit for Achilles tendinopathy patients. Passive modalities including ice, ultrasound, electrical stimulation, and low-level laser also lack support and so we do not recommend these treatments in our office. The current standard of care for Achilles tendinopathy includes a combination of rest, eccentric rehabilitation, and correction of mechanical faults. Studies have demonstrated excellent results in up to 85% of patients undergoing appropriate conservative care. Initially, patients may need to limit or stop activities that cause pain. Significant strains may require the use of crutches or a boot. Runners may need to switch to swimming, cycling, or other activities that limit stress to the Achilles tendon but will allow them to maintain cardiovascular fitness.
Eccentric exercise programs are effective for treating Achilles tendinopathy. Conflicting evidence leans toward the thought that eccentric training is more effective than concentric training for reducing pain and improving function. A proven program by Alfredson incorporates single leg eccentric heel drops off the edge of a step. Heel drops should be performed with the knee both straight and bent, three sets of 15 repetitions, twice per day for 12 weeks. Heel drops should occur slowly on a 4-10 second count. The patient should use the non-injured leg to return to the “heel up” start position, thereby avoiding concentric contractions. Moderate pain during this exercise is acceptable but if pain is excessive, the patient should assist downward motion with the non-injured leg.
“The evidence supports a slowly progressive loading program, rather than complete rest.” The goal of tendinopathy rehab is to carefully balance stimulating a controlled musculotendinous inflammatory response for healing without causing greater injury or exacerbating symptoms. Rehab should begin with moderate effort and low repetitions. Response to tensile loading may be assessed by the patient’s change in night pain. Increases in night pain indicate the current rehab load is excessive. Progression advances when the patient tolerates a given level of tensile load.This will be carefully managed by your treating healthcare provider.
Soft tissue manipulation, stretching, and myofascial release techniques are necessary to promote flexibility of the calf muscles and relieve symptoms. Joint manipulation may be appropriate along the kinetic chain, particularly the ankle.
Getting back to Sport
Athletes should introduce new activities slowly and avoid increasing activity, particularly running, by no more than 10% per week. Runners should begin on smooth, surfaces and start out at a lower intensity and distance- first increasing distance, then pace. Treadmill walking or running increases gastroc and soleus demand as compared to over-ground ambulation. Achilles tendinopathy patients should avoid wearing compression socks. Athletes should avoid training on unlevel surfaces, including hills. Return-to-play criteria for Achilles tendon strains or ruptures include the “Triple 5”:
- Ankle dorsiflexion is within 5 degrees of the uninjured side,
- Calf circumference (measured 10 cm distal to the tibial tuberosity) is within 5 mm of the uninjured side, and
- The patient is able to perform 5 sets of 25 single leg heel raises. (60)
Patients who fail a trial of conservative care should be referred, but proven alternatives are scarce. Medical co-management is of limited benefit. NSAIDs may relieve symptoms but have little long-term effect on outcome. Cortisone injections are unproven for the treatment of Achilles tendinopathy and carry a possible increased risk of tendon rupture. Extracorporeal shock-wave therapy (ESWT) or platelet-rich plasma (PRP) injections are controversial alternatives. ESWT (originally developed as lithotripsy) is thought to break up calcific deposits and stimulate fibroblast activity to encourage healing and may be appropriate for Achilles tendinopathy. PRP treatments consist of injecting platelet-rich plasma into a tendon to create a concentrated trigger of growth factors and chemoattractants for macrophages and fibroblasts, which gradually repair the damaged collagen. Some clinicians suggest benefit from PRP injections, but others refute its usefulness for Achilles tendinopathy, including at least one randomized clinical trial.
Surgical management is often considered for Achilles tendon ruptures, although several studies, including at least one randomized clinical trial, suggests at least equivalent results between surgical and conservative management.
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