Achilles Tendon Pain: Do You Need an Ultrasound or an MRI Scan?

A sore Achilles has a particular rhythm: stiff and tender first thing, easier once you are moving, back again after you sit down. Runners know it as the injury that arrives a few weeks after a new hill session or a longer run. The natural question is whether a scan would show what is going on and, if so, which one.

For most people the honest answer from NHS physiotherapy teams is that a scan is not needed at the start. This guide explains why, when ultrasound or MRI does come into it, and the one symptom, a sudden snap at the back of the ankle, that is an urgent care problem rather than a scan problem.

What Achilles tendinopathy is

The Achilles is the thick tendon joining your calf muscles to your heel bone. Midlands Partnership NHS Foundation Trust's musculoskeletal service describes Achilles tendinopathy as one of the most frequent ankle and foot injuries, which can occur when the tendon is overworked, and lists a sudden change in your usual activity, weaker muscles, reduced ankle movement, being overweight and diabetes among the risk factors.

Wrightington, Wigan and Leigh NHS Foundation Trust's physiotherapy leaflet adds that the problem is usually not inflammation: the tendon becomes irritated when asked to do more than it can cope with. It is common in runners but also affects less active people, with standing jobs listed as a risk factor and a typical age range of 30 to 60. The MPFT page describes the symptoms as stiffness and soreness that is worst in the morning and eases after a few minutes of activity, pain made worse by activity that involves long periods on your feet, and sometimes a lump on the tendon.

Why a scan is usually not the first step

The MPFT page says diagnosis is usually made from a consultation with your health care professional, covering how the symptoms started, their pattern and what you can and cannot do, and it states plainly that images or scans are generally not needed to confirm Achilles tendinopathy. The WWL leaflet says the same: in most cases no scans are needed, and the diagnosis is made from your symptoms, your history and an examination.

Both NHS sources put the work into load management and strengthening, none of which depends on a scan: reduce the activities that hurt without stopping completely, wear supportive shoes, consider a temporary heel raise, and build calf strength through staged exercises.

There is also a time rule. The NHS tendonitis page says a mild tendon injury should feel better within 2 to 3 weeks, and the MPFT page says to see a health professional if the pain shows no sign of improvement within a couple of weeks of self-help, or suddenly worsens.

Ultrasound or MRI: when each is used

If the picture is not clear, or the pain does not settle with the right treatment, a scan earns its place. Norfolk and Norwich University Hospitals' leaflet says an ultrasound scan or MRI scan may be requested to confirm the diagnosis and assess the severity, and the WWL leaflet describes ultrasound or MRI being used to rule out other causes when symptoms do not settle. The MPFT page says an ultrasound may be used if more information is needed.

Ultrasound is often the first choice because the tendon lies just under the skin. The NHS says an ultrasound scan is used to see images of the inside of your body, such as muscles and organs; for a tendon that means the sonographer can look at its thickness and structure, compare it with the other side and watch it move. The NHS says an MRI scan takes detailed pictures of the inside of your body and is used to help find the cause of symptoms and plan treatment; a clinician may choose it to see the heel bone and the tissues around the tendon in one examination, or when ultrasound has not answered the question. The choice is the clinician's, and neither scan is a treatment: a report of thickening or small tears usually confirms the examination and the loading programme continues. Our ultrasound vs MRI and what ultrasound can detect guides explain the trade-offs.

The snap that needs urgent care, not a private scan

There is one Achilles problem where the advice is completely different. The WWL leaflet lists a sudden pop at the back of the ankle, sudden severe pain, difficulty walking and being unable to rise onto your toes as possible signs of a rupture, and the MPFT page lists a snap or pop at the back of the lower leg, being unable to point your toes, dragging your foot and severe bruising. The NHS tendonitis page says to call 111 or use 111 online if you think you have ruptured a tendon or are in a lot of pain.

A rupture is diagnosed in person. Hull University Teaching Hospitals' patient information says a clinician examines you in a minor injury unit or emergency department and, if a rupture is suspected, puts your leg in a cast with the foot pointing down. An ultrasound scan, which Hull aims to carry out within 2 weeks, then confirms the rupture; X-rays, it notes, are not useful because there is no bone involvement. Hull says it can take 12 to 18 months to regain normal function. If that snap happens mid-race, the right place is urgent care that day.

How long recovery takes

Tendons heal slowly. The NNUH leaflet says the symptoms of Achilles tendinopathy usually become manageable within 6 to 12 months. The WWL leaflet says most people improve within 3 to 6 months with consistent management, that full recovery can take up to 12 months, and that strengthening should continue after symptoms improve. If you are weeks into a sensible programme and not improving, go back to your physiotherapist or GP, who may be the one to suggest imaging. Our guide to MRI of the leg and thigh covers other soft-tissue questions runners ask.

Having a private ultrasound or MRI

If a physiotherapist or GP has suggested a scan and the NHS wait is long, a private ultrasound or MRI is an option. Both can be self-referred at many clinics because neither uses ionising radiation, although the clinic will ask what the scan is for and a sonographer or radiologist decides whether it is the right test. You can compare ultrasound clinics near you or foot and ankle MRI clinics on FindScan and send an enquiry; the clinic contacts you to confirm whether it needs a referral and the next steps.

FindScan is a directory of independent, regulated imaging clinics: you compare clinics and send an enquiry, and the clinic contacts you. We are not a healthcare provider and nothing here replaces an examination by a physiotherapist or GP. If your Achilles pain started with a snap, or you cannot push up onto your toes, contact NHS 111 today rather than arranging a scan.