Is a partial tear of the posterior flexor tendon located over the superior portion of the tibia?

Posterior Flexor Tendon Tears and Anatomical Location

The posterior flexor tendon (tibialis posterior tendon) is located along the medial aspect of the ankle and runs behind the medial malleolus, extending to its insertion at the navicular bone and other midfoot structures, not over the superior portion of the tibia.

Anatomical Location of the Posterior Tibial Tendon

• The tibialis posterior tendon originates from the posterior aspect of the tibia, interosseous membrane, and fibula, but its tendinous portion primarily courses behind the medial malleolus before inserting into the navicular tuberosity and other midfoot bones 1
• The tendon passes through a groove behind the medial malleolus, not over the superior portion of the tibia 1
• Anatomically, the tibialis posterior muscle is contained within the deep posterior compartment of the leg along with the flexor digitorum longus and flexor hallucis longus, not in a separate fifth compartment 2

Imaging Evaluation of Posterior Tibial Tendon Tears

• MRI is the reference standard for evaluating tibialis posterior tendon tears, with high sensitivity for detecting both partial and complete tears 1
• Ultrasound can also effectively evaluate the tibialis posterior tendon with reported sensitivity of 100% and accuracy of 93% compared with surgical findings when performed by experienced operators 1
• When comparing MRI and ultrasound for tibialis posterior tendon pathology, MRI is slightly more sensitive, though this difference typically does not significantly affect clinical management 1

Clinical Presentation and Associated Findings

• Tears of the tibialis posterior tendon can occur following ankle sprains, though this is relatively rare with an incidence of approximately 1.04% 3
• Patients with tibialis posterior tendon tears typically present with persistent medial-sided ankle pain and progressive flatfoot deformity 3, 4
• Common clinical findings include inability to invert the heel when standing on tiptoe and loss of inversion power 4
• Tibialis posterior tendon tears are frequently associated with other pathologies, including talar osteochondral defects and ligament instability, which can confound diagnosis 3

Diagnostic Challenges

• MRI findings of tibialis posterior tendon tears can be subtle and may be missed on initial radiologist review 3
• Ultrasound has the advantage of allowing dynamic assessment of the tendon, which can be particularly useful for evaluating tendon subluxation or dislocation 1
• When evaluating tendon tears, it's important to assess tendon thickness, as increased thickness often correlates with partial tears 5

Treatment Considerations

• Surgical treatment options for tibialis posterior tendon tears include tendon repair, tendon advancement, or transfer of the flexor digitorum longus tendon 4
• Outcomes following surgical treatment are generally good, with one study reporting excellent results in 12 of 17 patients 4
• Patients should be counseled that persistent pain and poor outcomes are possible, particularly when associated pathologies are present 3

The posterior tibial tendon is a critical structure for maintaining the medial longitudinal arch of the foot, and tears can lead to significant functional impairment. Accurate diagnosis through appropriate imaging is essential for guiding treatment decisions.