Posterior tibial tendon insertion pain -15 yo male
Clinical History
A 15 year old male left ankle eversion injury while playing soccer 2 months ago – he stepped in a hole. Tender on palpation on the medial arch and navicular. Poor response to physiotherapy. Query posterior tibialis or plantar ligament injury.
Ultrasound Findings
The posterior tibial tendon navicular insertion contains a focal calcification (5mm long) with a cartilaginous connection to the navicular. The navicular has bone irregularity with increased echogenic maternal filling the gap between the focal area of the bone. There is increased vascularity within the tendon insertional part with the patient reporting this is the region of pain. Comparison with the right side shows a 10mm long irregular shaped bony area within the tibialis posterior tendon insertional part at the navicular. There is also mild vascularity with mild tenderness present.
Figure 1: Posterior tibial tendon insertion calcification less than 3 mm from navicular
Figure 2: Power Doppler shows vascularity in the posterior tibial tendon.
Opinion
Bilateral posterior tibial tendon insertions accessory navicular Type II, with increased vascularity and focal tenderness on the left indicating injury to the synchondrosis.
Figure 3a: Left foot showing accessory navicular Type II
Figure 4. Diagram of posterior tibial tendon accessory navicular.
Figure 3b: Bilateral accessory navicular Type II
Figure 5: Type I ossicle/sesamoid within tendon > 3mm from navicular; Type II ossicle cartilage connection (synchondrosis); Type III enlarged medial horn of the navicular
Follow up
Rest and ice on the foot without any intensive treatment “feels almost normal now”.
Discussion
Accessory navicular aka os navicularum or os tibiale externum.