Diagnostic ultrasound of the foot and ankle: what can the examination show?

The examination uses sound waves to create real-time images of tissue. It is done together with a conversation and a clinical examination. The method is painless and without radiation, and it can be repeated when needed [6].

Ultrasound is particularly suited to structures close to the skin, and is often available faster than MRI [6]. The researchers behind a study of the plantar fascia describe it as an established and gentle method that gives real-time images [5].

Ultrasound can show inflammation-like changes, wear and tears in tendons, muscles, bursae and joints. The practitioner can compare with a healthy area and scan again to follow the healing [6]. For problems in the ankle and foot, plantar fasciitis, Achilles problems and ligament injuries are mentioned as relevant issues [6].

In plantar fasciitis, the plantar fascia is described as thickened and with a darker, less echogenic structure at its attachment on the heel bone [5]. The guideline mentions thickening above 4 millimetres and a darker appearance as findings that suggest the condition [1], while a review article uses more than 5 millimetres at the attachment as the limit [4]. The sources thus use different cut-off values.

Ultrasound can also help separate plantar fasciitis from other causes of heel pain. The review article mentions that ultrasound is better than MRI for showing a plantar fibroma, a small nodule in the fascia, and that Achilles tendinopathy should be considered as a possible cause of heel pain [4].

Sound waves do not penetrate bone. For deep structures in joints or suspicion of a larger fracture, MRI or X-ray is more often the right choice, and ultrasound and MRI complement each other [6].

The result also depends on the person performing the examination. Ultrasound is described as operator dependent, because the image is affected by how the probe is held, the machine settings and how the foot is positioned. Visual assessment of the images can give poor agreement between different examiners [5].

A finding in the image does not by itself say what causes the pain. The guideline points out that a thickened plantar fascia and a darker appearance can also be seen in people without symptoms [1]. In a study that the guideline refers to, there was no association between heel pain and the thickness of the plantar fascia. That is a correlation, not a causal explanation, and it shows that thickness alone cannot determine how severe the symptoms are [1].

In the same way, a heel spur cannot be used to confirm the diagnosis, because it is found both in people with and without plantar fasciitis [2]. Findings in the image must therefore always be assessed together with the history and clinical examination [1][6].

In plantar fasciitis, the diagnosis is most often made from the history and examination, and imaging is usually not necessary [1][2]. The same applies to Achilles tendon pain, where ultrasound or MRI can exceptionally be used to rule out other disease [3]. In plantar fasciitis, ultrasound or MRI can confirm the diagnosis, and X-ray is occasionally used to rule out, among other things, a stress fracture [2].

The guideline states that imaging is usually not relevant when the patient meets the clinical criteria, and becomes relevant only when conservative treatment gives no improvement [1].

The practitioner applies a water-based gel to the skin and gently moves a probe over the area. You feel mild pressure. The scan itself usually takes 10 to 15 minutes, and the rest of the appointment is used for the history, clinical examination and a plan for treatment and exercise [6]. You do not need a referral from a doctor [6].

A chiropractor can examine the foot and ankle, assess whether ultrasound is a useful addition to the examination and go through the findings with you. You can read more about diagnostic ultrasound. If you have heel pain, there is a separate page about plantar fasciitis.

What can ultrasound of the foot show?

Ultrasound can show changes in tendons, muscles, bursae and joints, for example a thickened plantar fascia in plantar fasciitis. The findings must be interpreted together with the symptoms [1][5][6].

Is ultrasound of the foot and ankle painful?

The examination is painless and without radiation. You feel mild pressure from the probe [6].

Do I need a referral for ultrasound?

No, at Dr.Dropin you do not need a referral from a doctor [6].

Is ultrasound better than MRI?

The methods have different strengths, and they complement each other [6]. When measuring the thickness of the plantar fascia, no significant differences have been found between ultrasound and MRI [1], while ultrasound is better than MRI for showing a plantar fibroma [4].

How long does the ultrasound examination take?

The scan itself usually takes 10 to 15 minutes. The rest of the appointment is used for the history, clinical examination and a plan for treatment and exercise [6].

The page about plantar fasciitis describes heel pain under the foot. If you wonder about insoles, you can read about insoles at Dr.Dropin. You can find more articles in the overview of articles.

This article was written by Dr.Dropin Fysikalske and is based on the sources listed below. It gives general information and does not replace an examination by a healthcare professional.

The websites were accessed and read on 22 October 2026.

1. Koc TA Jr, Bise CG, Neville C, Carreira D, Martin R, McDonough CM. Heel pain - plantar fasciitis: revision 2023. J Orthop Sports Phys Ther. 2023. doi:10.2519/jospt.2023.0303. Link

2. Plantar fasciitt (Plantar fasciitis). NHI.no. Last updated 22 September 2025. Link

3. Akillessenebetennelse (Achilles tendonitis). NHI.no. Last updated 15 October 2024. Link

4. Plantar fascia: imaging diagnosis and guided treatment. Semin Musculoskelet Radiol. 2010;14(3):334-343. doi:10.1055/s-0030-1254522. Link

5. Bisi-Balogun A, Cassel M, Mayer F. Reliability of various measurement stations for determining plantar fascia thickness and echogenicity. Diagnostics (Basel). 2016;6(2):15. doi:10.3390/diagnostics6020015. Link

6. Diagnostisk ultralyd hos fysioterapeut eller kiropraktor (Diagnostic ultrasound with a physiotherapist or chiropractor). Dr.Dropin, service page. Accessed 22 October 2026. Link