Disclosures: Jalaluddin Baten, Medical Student: No financial relationships or conflicts of interest

Case Description: This patient had posterior right knee pain and left ankle pain that began 3 years ago following a reported growth spurt. She underwent a tarsal tunnel release to relieve the left ankle pain several years ago, but the right knee pain had persisted and remained undiagnosed despite an extensive work-up. Over the past 3 years, she had an inconclusive neurology evaluation, multiple EMGs, benign rheumatology evaluation, negative X-rays and MRI of the knee showing no structural abnormalities, several unsuccessful rounds of physical therapy, and orthopedic rule-out of intra-articular etiology. Physical examination was unremarkable on presentation. The patient was referred to a physiatrist, and ultrasound evaluation was done which revealed the popliteal vein directly deep to the tibial nerve about 2cm after branching from the sciatic nerve, as well as reproducible pain with sonopalpation and compression. An ultrasound-guided hydrodissection was performed to free the tibial nerve. The patient only developed partial relief as she could only tolerate 4cc of volume during the hydrodissection, but this prompted her to complete surgical decompression of the nerve. She is now 6 months post-surgery and remains symptom-free.

Setting: Outpatient sports-medicine clinic

Patient: A 13-year-old girl with undiagnosed right posterior knee pain. Assessment/

Results: The ultrasound evaluation and diagnostic block was able to diagnose this patient’s tibial nerve entrapment that was ultimately the cause of her symptoms. The hydrodissection was unsuccessful in providing permanent relief due to limited patient tolerance, but the ultrasound and injection were able to confirm her diagnosis which moved her towards the surgical route of treatment.

Discussion: This case presents the clinical and imaging findings seen in tibial nerve entrapment and emphasizes the strong diagnostic power of ultrasound in visualizing neuropathic causes of pain described in other literature.

Conclusion: Ultrasound imaging can be helpful in diagnosing the etiology of symptoms associated with tibial nerve compression in the posterior knee.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/ultrasound-diagnosis-of-an-entrapped-tibial-nerve-in-an-adolescent-a-case-report/