The heel is reported to be the most common site of enthesitis related foot pain [1, 2].

However there are other important "functional entheses" in the foot including where tendons wrap around bones that can also cause foot pain.

Heel and foot pain represent common reasons for referral into podiatry and physiotherapy services.

The diagnosis of spondyloarthropathy including Ankylosing Spondylitis, Psoriatic Arthritis and other Spondyloarthropathies may be missed if the symptoms are confined to the heel.

The failure to recognise inflammatory enthesitis may lead to a delay in diagnosis or even incorrect treatment including surgery.

Recognition of Achilles enthesitis

Achilles Enthesitis or primary inflammation of the insertion is associated with early morning stiffness of the insertion and pain.

This usually improves as the day goes on.

There are no obvious aggravating features such as sporting activity.

The role of injury or trauma as a trigger for enthesitis is still unclear.

Severe enthesitis may be painful and lead to limping throughout the day.

On clinical examination there may be tenderness and swelling at the insertion.

On clinical examination there may be tenderness only without swelling.

Some cases manifest as swelling of the retrocalcaneal bursa that is part of the Achilles tendon synovio-entheseal complex.

If enthesitis is severe there may also be swelling of the adjacent tendon.

X-rays may show new bone formation or erosion of the insertions.

Isolated enthesitis of the heel can be incredibly disabling.

Diagnosis of Achilles enthesitis

The diagnosis is based primarily on the history and physical findings.

X-rays may be normal in early disease.

Ultrasound may show inflammatory changes in the enthesis organ.

Magnetic Resonance Imaging may also show soft tissue changes and diffuse bone marrow involvement in the adjacent bone.

Key point - the imaging appearances of different pathologies that afflict the Achilles can look remarkably similar. Physicians need to carefully evaluate imaging reports in the context of the history and clinical findings.

Treatment of Achilles enthesitis

Correct foot malalignment where present

Heel supports to minimise trauma and to lessen stretch on Achilles may be tried.

Physiotherapy stretching exercises to loosen tight Achilles tendons to take strain of enthesis.

Anti-inflammatory drugs often work for milder or self-limiting disease.

The role of drugs such as methotrexate or sulphasalasine for isolated enthesitis is presently dubious

Resistant cases may respond well to anti-TNF [4].

As an alternative local injection of anti-TNF therapy may also work but the role of such strategies over cheaper options including steroids is unclear [5].

For really difficult cases there is evidence that switching to a second anti-TNF drug may help [6].

Other common causes of Achilles tendon region pain

Enthesitis may be misdiagnosed as the following conditions

Degenerative enthesopathy- This usually occurs in older subjects and tissue swelling is 2.5 cms away from the enthesis. Haglunds Deformity- This painful condition of the Achilles tendon synovio-entheseal complex region. Achilles tendonitis that typically occurs in active runners or sports activists. This represents a mixed bag of pathologies that includes: Achilles tendon thickening or degeneration

Inflammation of the tissue adjacent to the tendon or paratenon,

Over prominence of the tuberosity

Retrocalcanceal bursa and adjacent fat thickening or inflammation

New bone formation at the enthesis

For the most resistant cases there is evidence that surgery may help this group of cases [1, 2]. However it is essential to establish the correct diagnosis.

The MRI appearances of classical Achilles tendon injuries are shown below