Insertional Achilles tendonitis is a degeneration of the fibers of the Achilles tendon directly at its insertion into the heel bone. It may be associated with inflammation of a retrocalcaneal bursa or tendon sheath in the same area.
Symptoms and Clinical Presentation
Most patients report the gradual onset of pain and swelling at the Achilles tendon insertion into the back of the heel bone without specific injury. At first, the pain is noted after activity alone, but becomes more constant over time. The pain is made worse by jumping or running and especially with sports requiring short bursts of these activities. There is tenderness directly over the back of the heel bone, and often there is a bone prominence at this area. Positioning the ankle above a 90 degree position is limited by pain.
Cause (including risk factors)
The cause is primarily a degeneration of the tendon. The average patient is in their 40’s. Conditions associated with increased risk include psoriasis and Reiter’s syndrome, spondyloarthropathy, gout, familial hyperlipidemia, sarcoidosis, and diffuse idiopathic skeletal hyperostosis, as well as the use of medications such as steroids and fluoroquinolone antibiotics.
The Achilles tendon is the largest tendon in the body. It is formed by the merging together of the upper calf muscles and functions to bend the knee, point the toes down, as well as to slightly roll the heel to the big toe side of the foot. It inserts into the back of the heel bone. There may be a shelf extending off the back of the heel bone at the insertion site as well as a prominence of the heel bone in this area referred to as a Haglund's deformity, which can cause mechanical irritation of the Achilles tendon. Just as nose sizes and shapes vary, so there can be variations in the size and shape of these bone variations.
This remains primarily a clinical diagnosis. X-rays may show calcification deposits within the tendon at its insertion into the heel approximately 60% of the time, and their presence is associated with a more guarded success rate for nonsurgical treatment and a much longer recovery time if surgery is performed. X-rays may also demonstrate the Haglund's deformity.
Magnetic resonance imaging (MRI) remains the imaging modality of choice, because it can determine the extent of tendon degeneration as well as other factors, such as bursitis, which may contribute to posterior heel pain.
*Source: American Orthopaedic Foot & Ankle Society® http://www.aofas.org