Working Diagnosis:
Tibialis posterior tenosynovitis and longitudinal split tear secondary to medial retromalleolar osteophyte.

Treatment:
The case was discussed with Podiatry, and the patient initially opted for surgical management of the osteophyte. However, this was held due to the COVID-19 pandemic. During the interim, he was treated conservatively with supportive shoes and inserts after a diagnostic block was performed at the posterior tibialis tendon at the level of the osteophyte.

Outcome:
With the diagnostic block of the posterior tibialis tendon at the level of the osteophyte and conservative management, the pain improved. The patient decided to continue with conservative treatment with the option for potential surgical intervention if his pain would worsen in the future.

Author's Comments:
Ultimately, a comprehensive history and physical examination combined with point of care ultrasound provided an accurate diagnosis and prevented an unnecessary flexor hallucis longus tenosynovectomy and tarsal tunnel release. Point of care ultrasound is a cost-effective and efficient imaging modality that allows real-time visualization and dynamic scans to aid clinical findings.

Upon further review of the initial MRI of the patient, the malleolar osteophyte was visible but was not commented on. It was the ultrasound findings relayed to radiology prior to the new MRI that aided them in further characterizing his pathology.

Editor's Comments:
Given the complexity of medial ankle anatomy, accurately identifying the cause of medial ankle pain just by history and physical exam can be challenging in many cases.

Thickening of the posterior tibialis tendon and peritendinous fluid are ultrasonographic characteristics of tenosynovitis of posterior tibial tendon, which is often unrecognized form of posterior tibialis tendon dysfunction.

Ultrasound, as this case highlighted, is a relatively inexpensive and effective imaging modality when diagnosing pathologic conditions, leading to the medial ankle pain. It has been illustrated that ultrasound normally gives an accurate diagnosis of posterior tibialis tendon pathology and correlates well with the result of MRI. Ultrasound also has an advantage of being a dynamic study, allowing further assessment of the pathology and observation for pathological movement in real time as seen in this case.

References:
Ankle joint and forefoot: Anatomy and techniques. (2019, May 1). Radiology Key. Retrieved July 18, 2022, from https://radiologykey.com/ankle-joint-and-forefoot-anatomy-and-techniques-2/

Bare, A. A., & Haddad, S. L. (2001). Tenosynovitis of the posterior tibial tendon. Foot and ankle clinics, 6(1), 37-66.

Bellew, S. D., Colbenson, K. M., & Bellamkonda, V. R. (2017). Posterior tibial tendon tenosynovitis diagnosed by point-of-care ultrasound. Clinical Practice and Cases in Emergency Medicine, 1(4).

Lento, P. H., & Primack, S. (2008). Advances and utility of diagnostic ultrasound in musculoskeletal medicine. Current reviews in musculoskeletal medicine, 1(1), 24-31.

Kotnis, N., Harish, S., & Popowich, T. (2011, April). Medial ankle and heel: ultrasound evaluation and sonographic appearances of conditions causing symptoms. In Seminars in Ultrasound, CT and MRI (Vol. 32, No. 2, pp. 125-141). WB Saunders.

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