Causes / typical injury mechanism:

• The Achilles tendon connects the muscles of the posterior calf, plantaris, gastrocnemius, and soleus to the calcaneus heel bone. One of the largest tendons in the human body, the Achilles tendon translates force from the posterior calf muscles and enables plantar flexion, a key movement in locomotion and actions such as running and jumping.
• A key structure located on the anteroinferior wall of the Achilles tendon is the retrocalcaneal bursa, a fluid-filled cushion that helps to facilitate movement by reducing friction of the Achilles tendon with the surrounding tissue.
• Insertional Achilles tendonitis (IAT) and retrocalcaneal bursitis (RB) are 2 common presenting symptoms related to posterior heel pain. Achilles tendonitis is an overuse injury that is caused by excessive mechanical overloading of the gastrocnemius or soleus muscles.
• As the name suggests, IAT is differentiated from midportion Achilles tendonitis as IAT is localized from the tendon insertion to 2 cm upwards. RB is inflammation of the retrocalcaneal bursa that can be caused by ill-fitting footwear or overuse of the heel and ankle. It is commonly seen in dancers and ice skaters.

Classic history and presentation: Patients with IAT present with a sharp, achy pain in the posterior heel directly at the insertion of the Achilles tendon. Pain typically worsens with load-bearing activities and especially during the onset of exercise. IAT is not uncommon in recreational athletes who have recently increased their intensity and duration of exercise. Although IAT can be seen in sedentary patients, it is especially prevalent in recreational runners and athletes involved in sports requiring repeated running and jumping movements.

Patients with RB often display a slightly different presentation. They typically have erythema and swelling near the retrocalcaneal bursa, which is often tender to direct palpation. Activities that force the ankle to undergo dorsiflexion, such as uphill running, can further intensify the pain and cause compression of the inflamed bursa. RB is often associated with a variety of other foot and ankle disorders, such as Haglund deformities, rheumatoid arthritis, gout, reactive arthritis (Reiter syndrome), and psoriatic arthritis.

Prevalence: Posterior heel pain is a common injury that is prevalent in the general population.

• In fact, 1 in 8 patients over the age of 50 years report some type of heel pain.
• Injury to the Achilles tendon is often seen in clinical settings and is one of the of the most frequently reported overuse injuries in medical literature.
• Research indicates that males are slightly more affected than females.
• Estimates of annual incidence of general Achilles tendonitis in runners range between 7% and 9%.

Like IAT, RB is commonly seen in recreational athletes.

• Although the prevalence of RB has not been well documented, it is particularly common in ice skaters.
• In a study that examined approximately 100 ice skaters, researchers reported that nearly 34% were dealing with RB injuries. Both males and females seem to be affected.

Risk factors: There are a multitude of risk factors associated with IAT and RB. These include:

• Decreased plantar-flexor strength.
• Reduced subtalar joint range of motion.
• Increased foot pronation.
• Increased body mass.
• Advanced age.
• Other risk factors include systemic disease, genetic variants, and a family history of tendinopathy.

Pathophysiology: Researchers hypothesize multiple different mechanisms of injury for IAT, including overuse, decreased blood supply, reduced tensile strength, insufficient flexibility, and microtrauma of the tendon. These factors can cause irritation of the tendon and cause continued discomfort and pain.

Like IAT, RB can be caused by overuse injuries. Repetitive motions, such as running, can irritate the bursa and cause inflammation. When this occurs, patients can experience severe pain and discomfort in the posterior heel.