Collection: Achilles

The Achilles tendon is a thick and strong tendon that connects the gastrocnemius and soleus muscles of the leg to the heel bone. It is responsible for plantar flexion, which is the movement of the foot towards the ground. This movement is important for activities such as walking, running, and jumping. The Achilles tendon is able to withstand large forces and is the largest tendon in the human body. It provides both elasticity and shock-absorption to the foot. The tendon is capable of supporting tensional forces produced by movement of the lower limb.

The Achilles tendon can be damaged due to repetitive use or overloading, which is often the result of excessive exercise or training. These types of injuries are common among athletes, especially those who engage in sports or exercise activities and is linked to several factors, including overuse stresses, impaired vascularity, and inflexibility, among others. The main mechanism that is thought to contribute to the development of this condition is excessive loading during vigorous activities, such as running, without adequate rest periods. During activities issues with pronation and supination may effect the strain on the Achilles tendon. This can result in cumulative microtrauma to the tendon, as there is not enough time for the tendon to repair itself. Microtrauma occurs when there is non-uniform stress in the tendon, which is caused by different force contributions from the gastrocnemius and soleus muscles, creating frictional forces and localized collagen fibre damage.

The Achilles tendon has a limited blood supply throughout its length, as there are only a few blood vessels per cross-sectional area. The middle section of the tendon has even fewer blood vessels than other parts of the tendon, making it a common site for injuries. This lack of blood supply can make it difficult for the tendon to heal properly after an injury. Additionally, blood supply to the tendon decreases as a person ages.

Achilles Tendinopathy is a degenerative condition that affects the Achilles tendon. It is a non-inflammatory condition that often occurs as a result of overuse, particularly in athletes. The annual incidence rate of Achilles Tendinopathy is around 7-9% in elite runners. Tendinopathy is a general term used to describe clinical conditions of tendons that result from overuse. After a histopathological examination, the condition can be classified as either tendinosis or tendinitis depending on the pathology observed. Tendinosis is characterized by intra-tendinous degeneration, including collagen fibre disorientation and thinning, with no inflammation. In contrast, tendinitis is characterized by inflammation of the tendon.

People with Achilles Tendinopathy exhibit reduced and delayed muscular activity compared to those who are not affected. Specifically, there is a reduction in tibialis anterior activity before heel-strike and reduced activation of several muscles during weight acceptance after heel-strike, including rectus femoris, gluteus medius, peroneus longus, and medial gastrocnemius. Additionally, there is reduced activation of the gluteus maximus during the midstance phase, which can result in lower hip extensor moments. These reductions in muscle activity can impact biomechanical factors in gait, such as uneven ground reaction force, alterations in joint positions, and changes in temporospatial parameters. Lower hip extensor moments can result in increased joint moments and compensations down the kinetic chain, ultimately affecting the forces placed on the Achilles tendon.

Pronation issues may contribute to the development of Achilles Tendinopathy. Individuals who overpronate may experience a whipping action that can lead to microtears in the Achilles tendon. Normally, during the transition from heel-strike to midstance, the knee extends while the foot transitions to a supinated position, creating external rotation moments. However, in functional overpronation, the foot remains in a pronated position, creating opposing external and internal rotation moments. This produces a whipping effect that draws the Achilles tendon medially with greater ankle eversion, resulting in microtears. Additionally, people with poor flexibility of the triceps surae (the calf muscles) may use foot pronation as a compensation to gain range of motion during dorsiflexion.

Yes, orthotics can help alleviate the pain of Achilles tendinopathy and tendonitis. Effective orthotics such as Custom or Interpod orthotics use specific design features to reduce the forces involved during pronation. The most effective design feature being the rearfoot wedge to resist pronation. Orthotics can also support the foot and reduce the strain on the Achilles by assisting with supination, reducing the strain on the tendon and decreasing the likelihood of injury and inflammation. The best orthotics for Achilles tendonitis have design features including a rearfoot wedge, plantar fascia groove, and a cuboid notch to provide optimal support and pain relief.