The spring ligament (plantar calcaneonavicular) complex has two main components: the superomedial (SMCNL — the clinically important one) and the inferior (ICNL). The SMCNL supports the talar head medially and connects to the tibiospring component of the deltoid, forming the complete medial column ligamentous support. Spring ligament insufficiency is central to adult-acquired flatfoot deformity pathomechanics.
| Origin | Sustentaculum tali of the calcaneus (superomedial and inferior components) |
|---|---|
| Insertion | Medial and plantar navicular (superomedial component to the navicular beak; inferior component to the plantar navicular) |
| Actions | Primary static support for the talar head — prevents medial longitudinal arch collapse and talar head medial deviation in flatfoot |
|---|
Spring ligament tears are identified on MRI as discontinuity or signal change in the SMCNL on coronal views. In PTTD flatfoot, spring ligament insufficiency is present in 70-80% of cases and must be addressed at surgery (spring ligament repair or reconstruction alongside medializing calcaneal osteotomy and FDL tendon transfer) for optimal outcomes.
Superomedial calcaneonavicular ligament tear producing talar head medial deviation in adult flatfoot managed with ligament repair as part of reconstructive flatfoot surgery.
