Ankle and Foot Pain: Plantar Fasciitis and Achilles Tendinopathy

Heel pain that is at its worst in your first few steps in the morning, eases as you walk, then returns after a long day is almost always plantar fasciitis. Pain behind the ankle in the Achilles tendon is the other common presentation. Both are loading problems, and both are treated on the same principle.

Pathophysiology: plantar fasciitis

The plantar fascia is a thick band of connective tissue running from the heel bone to the base of the toes. It supports the arch and acts as a spring during walking and running. When the foot loads, the fascia stretches; when the toes extend at push-off, it tightens and stiffens the arch — the windlass mechanism.

Under repeated excessive load, the fascia at its attachment to the heel develops microscopic tearing and, as with other overloaded connective tissue, a degenerative rather than an inflammatory response: disorganised collagen, increased ground substance and vascular ingrowth. The name is a misnomer for the same reason tendonitis was — fasciosis would be more accurate.

The characteristic first-step pain has a mechanical explanation. Overnight the fascia shortens and the microscopic damage begins to knit in a shortened position. The first weight-bearing steps disrupt that, which is why the pain is worst then and settles as the tissue is loaded and lengthens.

Heel spurs are frequently seen on X-ray and are frequently blamed. They are better understood as a consequence of long-standing traction at the attachment than as the cause of the pain, and plenty of people have them without symptoms.

Pathophysiology: Achilles tendinopathy

The Achilles is the strongest tendon in the body and transmits very high loads. Tendinopathy occurs in two distinct locations, and the distinction changes treatment:

• Mid-portion, roughly 2–6 cm above the heel — a relatively poorly vascularised zone, and the more common site
• Insertional, where the tendon meets the heel bone — compression of the tendon against the bone plays a larger role here, which is why exercises that take the ankle into full dorsiflexion can aggravate it

The tissue changes mirror those in other tendinopathies: collagen disorganisation, matrix change, neovascularisation with accompanying nerve ingrowth. It is a failed adaptation to load, not an infection or an inflammation.

First-line treatment

For plantar fasciitis: calf and plantar fascia stretching done consistently, supportive footwear, avoiding barefoot walking on hard floors while it settles, and load management — reducing time on your feet rather than eliminating it. Shockwave therapy is a reasonable next step where symptoms persist beyond a few months.

For Achilles tendinopathy: progressive loading is the treatment, and the programme differs between mid-portion and insertional disease. Insertional problems generally need the loading kept out of end-range dorsiflexion initially.

Injection options

Injections are not a treatment on their own. Used well, they reduce pain enough that you can do the rehabilitation that actually changes the outcome. Used as a substitute for that work, they buy time and little else. These are the options we discuss.

Corticosteroid

A strong anti-inflammatory placed directly into the painful structure. Onset is fast — usually within days — and for someone who cannot sleep or cannot work, that speed matters.

The limitation is duration. The effect fades over weeks to months, and repeated injections into the same tendon carry a real risk of weakening the tissue. In tendon problems specifically, the evidence is uncomfortable: corticosteroid outperforms doing nothing in the short term but does worse over a year. We use it deliberately and sparingly, and we will tell you if we think it is the wrong choice for your problem.

Platelet-rich plasma (PRP)

A sample of your own blood is spun in a centrifuge to concentrate the platelets, which carry the growth factors involved in tissue repair. The concentrate is injected into the injured tissue.

PRP works in the opposite direction to corticosteroid: onset is slower, often several weeks, but the effect tends to last longer. Preparation matters — leukocyte-poor systems, which remove most white cells, have performed better than leukocyte-rich ones in comparative studies. We use a leukocyte-reduced system.

PRP is a genuinely promising option and we are honest about where the evidence sits: the trials are smaller and less consistent than we would like, and some professional bodies still recommend against it on those grounds. We think it is reasonable for selected patients, and we will say so if we do not think you are one.

How the injection is given

Accuracy matters more than most people expect. Injections placed by landmark alone miss the intended target a meaningful proportion of the time, particularly in deep joints like the hip and in the small spaces around the shoulder and wrist. Ultrasound guidance lets us see the needle reach the structure we are aiming at, which improves both accuracy and safety.

The injection itself takes a few minutes. Most people feel some soreness for a day or two afterwards. We usually ask you to avoid heavy loading of the area for a short period, then start or resume the rehabilitation programme.

A specific caution in the foot

Corticosteroid into the plantar fascia deserves particular care. It can give useful relief, but repeated injection into the fascia is associated with a risk of rupture, and with atrophy of the fat pad that cushions the heel — a problem that is difficult to reverse and can leave someone worse off than the original condition.

Corticosteroid is not injected into the Achilles tendon itself, because of the risk of tendon rupture. Where injection around the Achilles is considered, it is placed with care and under guidance.

PRP is used in both plantar fasciitis and Achilles tendinopathy, on the reasoning that the underlying problem is failed tissue repair. As elsewhere, the trial evidence is mixed and we will give you a straight account of it rather than overselling.

When to see a doctor

See someone if heel pain has not improved after a few weeks, if it is changing how you walk, or if it is stopping you exercising. Seek same-day assessment for a sudden sharp pain in the back of the ankle with difficulty pushing off — often described as feeling kicked in the leg — which may be an Achilles rupture.

Part of the other joints we treat. See also hip pain, elbow pain.

Written by Dr Gerard Ee. Last medically reviewed and updated: September 2026.