Midbody Achilles Tendinopathy (MPAT)
MIDBODY ACHILLES TENDINOPATHY
The Achilles tendon is made up of the soleus and gastrocnemius muscles and connects these muscles to the back of the heel. Mid-portion Achilles tendinopathy (MPAT) is a common painful acute or chronic disorder involving the mid-portion of the Achilles tendon.
Pathology
Chronic MPAT is associated with degenerative changes in the tendon. The disease is therefore characterised as a tendinopathy rather than tendinitis or tendinosis. The Achilles tendon is (together with the plantaris tendon) surrounded by a paratenon. In many cases of Achilles tendinopathy, the condition is accompanied by paratendinopathy.
MIDBODY ACHILLES TENDINOPATHY DIAGNOSIS
Diagnosis is based on the clinical features, along with location of the pain. The spot of maximum pain and painful swelling in MPAT is located 2 to 6 cm proximal to the insertion, whereas in case of insertional Achilles tendinopathy, the spot of maximum pain is at the tendon-bone junction. Symptoms can be exacerbated when getting up after a period of rest.
Diagnostic imaging such as ultrasound may be considered to rule out other causes of Achilles tendon pain or to establish the diagnosis of MPAT when in doubt.
The cause of MPAT is likely to be multifactorial and may include (but not limited to) advanced age, obesity, hypertension, diabetes, and steroid us. The onset of MPAT in athletes may also be influenced by poor training habits including excessive training, training on hard or sloping surfaces, and abrupt changes in routine.
It has been hypothesised that the healing of injuries of the Achilles tendon as a result of overuse involves the penetration of small blood vessels from the paratenon into the tendon in order to increase healing by providing improved blood flow. However, these small blood vessels are accompanied by small nerve fibres with high concentrations of nociceptive substances including glutamate, substance P, and calcitonin gene-related peptide (CGRP). Those small nerve fibres are considered the cause of pain in chronic MPAT.
‘In elite long-distance runners, the lifetime risk of Achilles tendon injury is approximately 50%. However, individuals of all activity levels and all ages may present with similar complaints. Approximately 30% of all of these patients tend to have a sedentary lifestyle’
Patients not responding to conservative treatment for >6 months may be referred for shockwave therapy.
