Achilles tendonitis is a common condition characterized by pain and stiffness in the tendon connecting the calf muscle to the heel bone. This injury, often linked to overuse, typically results in localized pain that worsens with activity. Heel inserts, also known as heel lifts or heel cups, are frequently recommended as a straightforward, non-invasive method for managing the discomfort associated with this condition and are often part of a larger recovery strategy.
The Biomechanical Function of Heel Inserts
The primary way heel inserts provide relief is by altering the mechanics of the ankle joint during walking and standing. By raising the heel inside the shoe, the insert effectively shortens the distance between the calf muscle and the heel bone, the attachment point of the Achilles tendon. This mechanical shortening immediately reduces the tensile strain placed on the tendon.
During the normal walking cycle, the ankle moves into dorsiflexion (foot toward the shin), which stretches the Achilles tendon. A heel lift limits the total amount of dorsiflexion the ankle can achieve, protecting the tendon from excessive stretching. This also reduces compressive forces at the insertion site, particularly in cases of insertional tendinopathy. This offloading effect decreases the overall load on the tendon, helping to calm the pain response and allowing the inflamed tendon to rest.
Selecting the Appropriate Insert Materials and Height
Choosing the correct heel insert involves considering both the material composition and the required height of the lift. Inserts are generally made from soft, cushioned materials (like silicone) or firmer materials (like dense rubber). Soft materials provide shock absorption, but firmer materials are often preferred because they maintain their structural height under the body’s weight, providing a consistent reduction in tendon strain. If a material is too soft, compression may negate the intended elevation effect.
The height of the lift is important, with recommendations suggesting a minimum of 8 to 12 millimeters to achieve a meaningful biomechanical change.
Inserts must be used bilaterally (in both shoes), even if only one tendon is affected. Using a lift in just one shoe can create a functional leg length discrepancy, potentially leading to discomfort in the hips and lower back. Once symptoms resolve, reliance on the heel lift should be reduced gradually through a tapering process. This involves slowly decreasing the height over several weeks, encouraging the tendon to adapt to a normal, unassisted length.
Integrating Inserts into a Comprehensive Treatment Plan
While heel inserts provide temporary relief and offloading, they should not be viewed as a standalone cure for Achilles tendonitis. The inserts address mechanical strain but do not restore the strength and capacity of the damaged tendon, which is essential for long-term recovery. Therefore, they are best utilized as a supportive measure within a broader rehabilitation protocol.
Activity modification (reducing activities that aggravate pain) is a necessary first step. Physical therapy is fundamental, particularly focusing on eccentric exercises. These exercises, which involve lengthening the calf muscle while contracting it under load, are the standard for rebuilding the tendon’s strength and load tolerance.
Stretching protocols for the calf muscles are often included, though caution is advised in the early stages. Aggressive stretching can increase compressive forces, especially for pain at the tendon’s insertion point. Pain management techniques, such as applying ice and using non-steroidal anti-inflammatory drugs (NSAIDs) under guidance, help control inflammation and discomfort. The inserts minimize pain, allowing the patient to engage in the necessary long-term strengthening and rehabilitation that addresses the root cause of the injury.