The Achilles tendon, a strong band of fibrous tissue, connects the calf muscles at the back of the lower leg to the heel bone. This robust tendon plays a significant role in everyday movements such as walking, running, and jumping by allowing the foot to push off the ground. When this tendon becomes shortened, it can restrict the ankle’s normal range of motion, affecting how a person moves and stands.
What is Achilles Tendon Shortening?
Achilles tendon shortening, sometimes referred to as equinus deformity, occurs when the Achilles tendon and the associated calf muscles become tight and inflexible. This tightness prevents the ankle from bending upwards adequately, a movement known as dorsiflexion. In a typical ankle, the foot should be able to move upward at least 10 degrees beyond a neutral, flat position. When this movement is restricted, the foot cannot comfortably achieve a flat-footed stance on the ground.
This condition limits the natural flexibility of the ankle joint. Individuals with Achilles tendon shortening often find it challenging to bring their toes closer to their shin. The restricted motion can alter how pressure is distributed across the foot during walking, leading to compensatory movements throughout the lower limb and even into the back.
Common Causes and Symptoms
Achilles tendon shortening can stem from various factors, some present from birth and others developing over time. Congenital equinus, for instance, means a person is born with a naturally shorter Achilles tendon or tight calf muscles. Acquired causes are more common and include prolonged use of high-heeled shoes, which keeps the calf muscles in a shortened position over extended periods. Muscle imbalances, where certain muscle groups are stronger or tighter than others, can also contribute to the condition.
Neurological conditions that affect muscle tone, such as cerebral palsy or a stroke, can lead to increased muscle stiffness and shortening of the Achilles tendon. Similarly, prolonged immobilization, perhaps after an injury or surgery where the foot is kept in a pointed position in a cast, can cause the tendon to adapt and shorten.
People experiencing this condition often exhibit distinct signs, such as difficulty walking flat-footed, which sometimes manifests as toe-walking, particularly in children. Pain may occur in the heel or calf, especially after activity, due to the constant strain on the shortened tendon and surrounding tissues.
The body often compensates for the limited ankle motion, leading to secondary issues in other joints. This can involve hyperextension of the knee, increased arching of the lower back, or abnormal hip rotation, all attempting to achieve a flat-footed stance. The altered gait can also contribute to various foot problems like bunions, hammertoes, and metatarsalgia, as abnormal pressure points develop across the foot. Persistent tightness can also increase the risk of developing plantar fasciitis due to the increased tension on the plantar fascia.
How It Is Diagnosed and Treated
Diagnosis typically begins with a physical examination by a healthcare professional. During this assessment, the practitioner will observe the patient’s gait and evaluate the range of motion in the ankle joint. A specific test, known as the Silfverskiöld test, helps differentiate between tightness in the soleus muscle (which crosses only the ankle) and the gastrocnemius muscle (which crosses both the knee and ankle). This test involves assessing ankle dorsiflexion with the knee both extended and bent. Imaging studies, such as X-rays, may be performed to rule out other bone-related issues or deformities, and an MRI might be used to assess the health of the Achilles tendon itself and surrounding soft tissues. Once diagnosed, treatment approaches vary based on the severity of the shortening and its underlying cause, often starting with non-surgical methods.
Non-Surgical Approaches
Physical therapy is a common initial intervention, focusing on a structured program of stretching exercises designed to lengthen the calf muscles and the Achilles tendon. These exercises aim to gradually improve ankle dorsiflexion and restore flexibility. Orthotic devices, such as heel lifts inserted into shoes, can temporarily reduce the strain on the tendon by elevating the heel. Custom ankle-foot orthoses (AFOs) may be prescribed to provide support and maintain the foot in a more neutral position. Night splints are often used to keep the ankle in a gentle dorsiflexion stretch overnight. In some instances, serial casting, where a series of casts are applied and progressively adjusted to stretch the tendon, may be employed over several weeks.
Surgical Interventions
When conservative methods do not yield sufficient improvement, surgical interventions may be considered. These procedures generally aim to lengthen the tightened tendon or muscle fibers. A common surgical approach is a gastrocnemius recession, where the gastrocnemius muscle is surgically lengthened, or a more direct Achilles lengthening procedure, which involves making small incisions in the tendon to allow it to stretch.
Recovery from non-surgical treatments typically involves consistent adherence to stretching and orthotic use, with gradual improvement over weeks to months. Surgical recovery often requires a period of immobilization in a cast or boot, followed by physical therapy to regain strength and range of motion, with full recovery potentially taking several months.
Preventing Achilles Tendon Shortening
Preventing Achilles tendon shortening largely involves maintaining the flexibility and health of the calf muscles and Achilles tendon. Regular stretching exercises are highly recommended, specifically targeting the calf muscles and the tendon itself. Performing these stretches consistently, ideally daily, can help maintain or improve ankle dorsiflexion. Simple stretches, like leaning against a wall with one leg back and the heel on the ground, can be very effective.
Consideration of appropriate footwear also plays a significant role in prevention. Limiting the prolonged use of high-heeled shoes can prevent the calf muscles from adapting to a shortened position. Opting for shoes with a lower heel height and good arch support promotes a more natural foot and ankle alignment. Maintaining an active lifestyle, which includes activities that encourage a full range of motion in the ankle, helps prevent muscle stiffness and shortening. Addressing any underlying medical conditions, such as neurological disorders, with appropriate medical management can also help mitigate their contribution to tendon shortening.