MRI NEWSLETTER: The Spring Ligament, PTT Tear and Adult Acquired Flatfoot Deformity on MRI

The posterior tibial tendon is the primary stabilizer of the foot. Other stabilizers include the spring ligament, the tarsal sinus ligaments and plantar fascia. The spring ligament complex consists of the tibio-spring component of the deltoid ligament and the calcaneonavicular ligament , which limits plantar flexion of the talus and stabilizes the talocalcaneal navicular joint. The tarsal sinus ligaments (cervical and interosseous ligaments) limit medial deviation of the talar head. To surgically correct flatfoot deformity both PTT and Spring Ligament injuries must be addressed. Frequently there is a combination of posterior tibial tendon injury, spring ligament injury and tarsal sinus ligament injury that leads to flatfoot deformity in adults and results in hindfoot valgus deformity.

The tibio-spring ligament is a portion of the deltoid ligament and has a wide attachment to the SM-CNL. The spring ligament (navicular calcaneal ligament) has 3 components that extend from the calcaneus to the navicular. The superior medial (SM-CNL) band is the most important portion of the ligament. Inferior to the SM-CNL band is the medioplantar oblique ligament and most inferior is the inferoplantar ligament. The SM-CNL is the strongest component and should be emphasized when reading MR exams. The SM-CNL extends from the sustentaculum tali to the dorsal aspect of the medial navicular. Immediately superior to the SM-CNL is the posterior tibial tendon. A thin synovial layer separates the spring ligament and the posterior tibial tendon and this is called the glide zone.

When the surgeons are discussing the spring ligament they are frequently referring to the tibio-spring ligament and the SM-CNL, which I call the spring ligament complex. In fact, a tear at the junction of the tibio-spring ligament and the SM-CNL is one of the more common tears and is called the “spring ligament tear” by the surgeons.

Read the full article here: The Spring Ligament, PTT Tear and Adult Acquired Flatfoot Deformity on MRI
By Dr William Renner