Peroneus longus tendon strain

Case contributed by Walid Al-Deeb


Pain right navicular area. Injury 2 weeks ago. Difficulty weight bearing.

Patient Data

Age: 50 years
Gender: Male

Soft tissue swelling noted over both malleoli, anterior and posterior aspect of ankle joint and lateral aspect of foot. No fracture is seen. Possible accessory ossification adjacent to the tip pf the lateral malleolus or site of old fracture.



The ankle and subtalar joints appear normal. Very subtle areas of minor subchondral edema are noted at the hallux and 2nd TMTJ. The cartilage here is preserved and elsewhere the visualized joints appear normal. There is no evidence of any dislocation.

There is a large sized corticated bone fragment lying at the distal aspect of the lateral malleolus. This incorporates the ATFL and partially the PTFL and CFL. It is difficult to be certain whether this represents an old avulsion injury or an accessory ossicle (sub fibulare). There is certainly some minor intraosseous cystic change at the interface with the lateral malleolus.

The lateral ligaments are intact as are the deep and superficial deltoid ligaments and spring ligament.

However moderate thickening to the anterior aspect of the superficial deltoid ligament is in keeping with a previous injury. There is a small amount of fluid within the tibialis posterior tendon sheath but the tendon itself appears normal.

At the peroneal groove of the plantar aspect of the cuboid, there is slight hyperintense thickening to peroneus longus tendon extending from this point up to and including its insertion at the plantar aspect of the base of the hallux metatarsal. This is in keeping with a severe strain and probable partial thickness avulsion injury.

The remaining medial and lateral tendons are intact and normal as is the Achilles tendon.

There is some minor hyperintense thickening to the plantar fascia in keeping with fasciitis with some entheseal edematous changes within the calcaneal tuberosity.

Marrow elsewhere returns a normal signal. In particular, there is no evidence of a fracture.

Annotated image

Single slice axial PD fat saturated sequence at the level of peroneus longus tendon insertion comparing two different patients.

Note the abnormal and normal appearances of the peroneus longus tendon at the insertion.

Annotated image

Arrows point to the peroneus longus tendon in the same plane.

This image is to demonstrate the level of the peroneal groove of the plantar aspect of the cuboid.

Note the signal changes demonstrated on the axial PD fat sat sequence (yellow arrow).

Case Discussion

Peroneus longus muscle originates from the fibula and superior tibiofibular joint and inserts into the plantar aspect of base 1st metatarsal and medial cuneiform, passing deep to long plantar ligament.

Its function is t plantar flex and evert the foot. To support the lateral longitudinal and transverse arches.

Nerve supply is via the superficial peroneal nerve.

This patient presented with pain in the plantar aspect of her foot. This case demonstrates the necessity of ensuring a good review of the tendon along its entirety. 

I'd like to thank Dr H Patel for supervising, contributing and assisting me with this case.

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.