Achilles Tendinopathy
What is Achilles Tendinopathy?
The Achilles tendon is the largest and strongest tendon in the human body, but is simultaneously a vulnerable link in the locomotion chain. 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 force on the tendon. Consistent with other types of acute strains, Achilles tendon injuries may occur when the musculotendinous unit transitions from deceleration to propulsion. Strains occur when collagen fibers are stretched by more than 4%, whereas ruptures occur when stretch exceeds 8%.
Unlike acute injuries that cause inflammation, tendinopathy is characterized by repeated overloading, microtearing, failed healing, and subsequent tendon changes that can lead to degeneration. The process begins with collagen fiber disruption and ends in a disorganized healing process that fails to regenerate a “normal” tendon.
Injuries to the Achilles tendon may be classified as “insertional” or “non-insertional.” Insertional tendinopathy, as its name implies, describes damage to tendon fibers at their insertion on the back part of the heel. This process may result in calcification and bony build up producing a prominent enlargement of the back part of the heel, also called a “Haglund deformity” or “pump bump.” Non-insertional Achilles tendinitis most commonly involves the vulnerable “watershed area”, 2-6 cm above the heel. This region of the tendon has a smaller cross-sectional area, has relatively poor blood supply, and is subject to a repetitive “wringing” motion during normal motion of the foot during walking. This susceptible mid-section is the most common site for degeneration and rupture.
Two-thirds of all Achilles tendon injuries involve athletes, especially those during speed training or sprinting. Runners are up to 10 times more likely to suffer Achilles tendon injuries compared to age-matched controls and it is expected that one in twenty recreational runners will develop Achilles tendinopathy. The Achilles is the most common site of tendinopathy in runners. Runners who assume a midfoot or forefoot strike pattern may be at even greater risk of injury. Not surprisingly, a higher risk has been identified in other sports that involve running or jumping. The estimated incidence of Achilles tendinopathy is: running sports, 53%; soccer, 11%; dance, 9%; gymnastics, 5%; racquet sports, 2%; football, 1%.
Risk factors for Achilles can injury include any combination of 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. Other intrinsic risk injury evaluation and assessment factors include prior lower limb fracture, excessive pronation, pes planus,
an excessively high arched foot, calf inflexibility or weakness, previous Achilles
injury and limited ankle mobility.
What Does Achilles Tendinopathy Look and Feel Like?
Patients may present with symptoms from an acute strain or a more gradual onset from 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.
It will be important to also contributory functional deficits throughout the kinetic chain including ankle, knee, hip, low back and core. Weakness in other tendons of the foot/ankle, hamstrings, the glutes, or core can contribute to faulty mechanics and add more stress to the Achilles tendon in complex movements and activities. It has also been found that stiff through the ankle and big toe contributes to more stress to the Achilles as it changes the dynamic foot motion during normal walking gait and higher level exercise like running, hiking, jumping, etc.
How Do We Treat Achilles Tendinopathy?
Nonoperative treatment is the mainstay for Achilles tendinopathy. “Traditional” treatment plans based solely on rest, physical therapy modalities, orthotics, and NSAIDs have failed to demonstrate benefit for Achilles tendinopathy patients and lack support in the literature. The current standard of care for Achilles tendinopathy includes a combination of rest, strengthening rehabilitation, and correction of mechanical faults - this could be anywhere in the kinetic chain. 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 be advised to switch to swimming, cycling, or other activities for a certain period of time that limit stress to the Achilles tendon.
Eccentric strengthening programs are effective for treating Achilles tendinopathy. Typically, moderate pain during exercise is acceptable to rebuild the tendon, however, if pain is excessive, the patient should decrease the intensity, frequency or repetitions of an exercise. The evidence supports a slowly progressive loading/strengthening program, rather than complete rest. The goal of tendinopathy rehab is to carefully balance stimulating a controlled inflammatory response 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 as increases in night pain indicate the current rehab load is excessive. Progression advances when the patient tolerates a given level of tensile load.
Soft tissue manipulation, stretching, and myofascial release techniques are necessary to promote flexibility of the calf muscles. The use of manual therapy and instrument-assisted soft tissue mobilization (IASTM) to release adhesions within the Achilles tendon can help improve tendon health. As an additional benefit, IASTM may accelerate healing, possibly via controlled microtrauma. Manipulation may be necessary to eliminate restrictions in the kinetic chain, particularly within the ankle and hip. There may be a time and a place for passive support during highly symptomatic cases where a heel lift or arch support is necessary to correct foot posture.
Athletes should introduce new activities slowly and avoid increasing activity, particularly running, by 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. Athletes should avoid training on unlevel surfaces, including hills. Treadmill walking or running increases the demand through the Achilles compared to over-ground walking or running. Achilles tendinopathy patients should typically avoid wearing compression socks.
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.
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. One systematic review concluded: "The findings give no evidence of superior long-term patient reported outcomes for surgical treatment over nonoperative treatment."
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