Ankle equinus

What is ankle equinus, and how common is it?

Ankle equinus (also called equinus deformity) means less upward bending of the ankle (dorsiflexion), often from tight calf muscles¹. No agreed amount of lost movement defines it: cut-offs of under 10, under 5 and under 0 degrees are all used². In otherwise healthy people, the non-neuromuscular form is often called subtle or silent³. It is very common among people who go to a podiatric clinic with a new foot or ankle problem¹, but how common it is in the general population isn't known.

What causes ankle equinus, and who gets it?

Ankle equinus can come from tight or contracted calf muscles or surrounding soft tissues, bony restriction, or nerve and muscle conditions⁴. In children, cerebral palsy and idiopathic toe walking (no clear cause) are the most common causes⁴. In adults with diabetes, equinus goes with slightly higher foot pressure, a link rather than proof it causes ulcers⁵. With diabetes, mention reduced ankle movement at your regular foot check.

What does it feel like, and how is it diagnosed?

Ankle equinus can be diagnosed on a physical examination⁴; when idiopathic toe walking is suspected and there is no developmental delay or abnormal neurological finding, imaging is generally unnecessary⁴. A clinician measures how far your ankle bends upward with the knee straight, then bent, holding the foot neutral⁴. This helps tell a tight gastrocnemius (the main calf muscle) from a tight whole calf group⁴. The weight-bearing lunge test, where you lean forward over your foot, gives consistent results between clinicians⁶. In children with idiopathic toe walking, reduced ankle movement is linked with trouble keeping the heels down when squatting⁷. A podiatrist also checks other causes of a stiff ankle, such as posterior ankle impingement, rather than assuming simple calf tightness⁴.

What helps first?

A guided stretching and strengthening programme from a physiotherapist or podiatrist, with gait training and home exercises, is the usual first step⁴. When the ankle is still flexible, it's often all that's needed⁴. Stretching may help, though it isn't clear whether it helps adults with diabetes and equinus any more than usual activity³⁸. No set dose is given⁴. Avoid flat shoes; rocker-soled shoes may be suggested⁹. If you have diabetes and are at risk of foot ulcers, have both feet checked before you start exercising¹⁰.

What helps if that isn't enough?

If stretching and physiotherapy haven't helped, ask whether a tight gastrocnemius is the problem and whether referral to a foot and ankle surgeon is right. Calf-lengthening surgery (gastrocnemius recession) is most likely to help adults when the problem is chronic plantar fasciitis with a tight gastrocnemius¹¹; it is less clear whether it helps other adult foot problems¹². Calf-lengthening surgery is an established option that often helps children with cerebral palsy¹². Risks such as calf weakness and nerve injury are uncommon but real¹³, so ask about them. With diabetes, asthma or high blood pressure, expect a pre-operative assessment visit.

How long does it take to get better, and can it come back?

When the ankle is still flexible, guided stretching and home exercise often settle it⁴. Keep up the exercises your clinician sets, and ask for a review point; how long recovery takes isn't clear yet. Stretching isn't known to stop it coming back³. After calf-lengthening surgery it recurs in about 1 in 20 people, usually milder, and most return to usual activity within 3–4 months, building up gradually¹⁴. With diabetes, well-fitting protective footwear, and never walking without foot protection, help prevent ulcers¹⁵.

What can make it serious?

• You have new numbness, tingling, pins and needles or weakness in your foot that has come on gradually.
• Your child walks on tiptoe and also can't stand with heels down, has one side different from the other, has very bulky calves, or seems unusually stiff or unsteady.
• Your pain is getting worse, or doesn't settle with rest, less activity or pain relief.
• You have lost weight without trying.
• You have pain at night or at rest that doesn't settle.
• Your cast is loose, too tight, cracked, dented, soft, wet or smelly, is rubbing, or has discharge or blood coming through it.
• You have had foot surgery and the wound opens, keeps bleeding or starts to leak.
• You have diabetes, poor circulation or reduced feeling in your feet and notice a new wound, sore, blister or colour change on your foot, or a sore that isn't healing.
• You have diabetes or reduced feeling in your feet and one foot becomes red, hot or swollen, or suddenly changes shape, even if it doesn't hurt (possible Charcot foot).
• You feel a sudden snap or pop at the back of your ankle or calf, as if you were kicked, and then find it hard to push off or stand on tiptoe.