48 year old male came with history of redness and swelling in the posteromedial aspect of the right ankle. Ultrasonography showed mildly thickened tibialis posterior tendon with significant amount of fluid collection around the tendon. No effusion in the ankle joint/ No DVT / No varicose veins. Features are consistent with tibialis posterior tenosynovitis.
Discussion:
Tenosynovitis is inflammation of tendon sheath. It can be caused by trauma, pyogenic infection, tuberculosis, seronegative spondylarthropathies or rheumatoid arthritis.
USG features are:
- Thickened tendon.
- Fluid collection around the tendon.
- Mildly increased vascularity within the tendon.
MRI features: Usually acute presentation.
- Fluid collection around the tendon in its proximal aspect.
- Signal change within the tendon is usually not seen in the acute stage and will be seen in chronic stage.
We need to differentiate the tenosynovitis with the paratendonitis which occur more in the distal aspect of the tendon. paratendonitis seen on MR as partially circumferential high signal intensity located distally around the posterior tibialis tendon. This signal intensity is usually slightly hypointense to fluid.