Presentation
Swelling and pain on the posterior inferior aspect of right ankle medial malleolus for 8 years. No trauma.
Patient Data
There is swelling on the posterior inferior aspect of the right medial malleolus.
There is hypertrophic bony prominence involving talocalcaneal joint in AP view. There is a continuous C-shaped arc on a lateral ankle radiograph.
Talo-calcaneal joint
- joint space reduction (compare with the asymptomatic side)
- joint is bridged by soft tissue showing fibrillary echo pattern
- a cystic lesion (4 x 3 x 2 mm) is seen abutting joint line
- the neck of this lesion is seen extending into the talocalcaneal joint. The defect is seen in bridging fibrillary soft tissue.
Talus
- bony hypertrophic prominence on medial aspect abutting talocalcaneal joint
- it increases the distance between flexure digitorum tendon and neurovascular bundle in comparison to asymptomatic side
Posterior tibial nerve
- edema of medial branch of nerve at and just proximal to the talus
- this branch shows elevated course due to the hypertrophic bone of talus
- cross sectional area of the nerve is double (6 mm2) as compared to asymptomatic left side (3 mm2) at the same level
- lateral branch and calcaneal branch show normal echo pattern
Medial tendons
- normal echopattern
Vessels
- patent
Case Discussion
Young female presented with medial ankle region swelling which she noticed a few years back. Plain radiograph shows findings of the talocalcaneal joint coalition.
Ultrasound shows fibrillary soft tissue bridging two bones. There is no ultrasound signature of either echogenic bone or anechoic cartilage. There is a ganglion sitting on this coalition with its neck extending into the joint. The ganglion abuts one of the veins but not the nerve. The altered contour of talus results in elevation of medial branch of tibial nerve; along with nerve edema.
The coalition is a developmental condition. The coalition can be of three different types: bony, cartilaginous, fibrous. Comparision with the asymptomatic normal side is helpful.