Achilles tendonitis implies an inflammatory response, but this is very limited because there is little blood supply to the Achilles tendon. More appropriate descriptions are inflammation of the surrounding sheath (paratenonitis), degeneration within the substance of the tendon (tendinosis) or a combination of the two.
Symptoms and Clinical Presentation
Paratenonitis presents in younger people. Symptoms start gradually and spontaneously. Aching and burning pain is noted especially with morning activity. It may improve slightly with initial activity, but becomes worse with further activity. It is aggravated by exercise. Over time less exercise is required to cause the pain.
The Achilles tendon is often enlarged, warm, and tender approximately 1 to 4 inches above its heel insertion. Sometimes, friction is noted with gentle palpation of the tendon during ankle motion.
Tendinosis presents similarly but typically in middle-aged people. If severe pain and limited walking ability are present, it may indicate a partial tear of the tendon.
Cause (including risk factors)
The cause of paratenonitis is not well understood although there is a correlation with a recent increase in the intensity of running or jumping workouts. It can be associated with repetitive activities which overload the tendon structure, postural problems, such as flat foot or high-arched foot, or footwear and training issues, such as running on uneven or excessively hard ground or running on slanted surfaces. Tendinosis is also associated with the aging process.
The Achilles tendon is the largest tendon in the body. It is formed by the merging together of the upper calf muscles and inserts into the back of the heel bone. Its blood supply comes from the muscles above and the bony attachment below. The blood supply is limited at the “watershed” zone approximately 1 to 4 inches above the insertion into the heel bone. Paratendonitis and tendinosis develop in the same area.
There is enlargement and warmth of the tendon 1 to 4 inches above its heel insertion. Pain and sometimes a scratching feeling may be created by gently squeezing the tendon between the thumb and forefinger during ankle motion. There may be weakness in push-off strength with walking. Magnetic resonance imaging (MRI) can define the extent of degeneration, the degree to which the tendon sheath is involved and the presence of other problems in this area, but the diagnosis is mostly clinical.
*Source: American Orthopaedic Foot & Ankle Society® http://www.aofas.org