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Background: The spring ligament has been reported to be composed of the inferior calcaneonavicular and supero-medial calcaneonavicular ligaments. We investigated the lower layer of the spring ligament fibrocartilage complex under the fibrocartilaginous surface, identified three distinct structures, and examined the morphology and running patterns of their fiber bundles.
Methods: Forty-eight cadaveric feet were examined. After ablation of the ankle joint and extirpation of the talus, the surface cartilage of the spring ligament fibrocartilage complex was carefully removed with forceps, and the length, width, and thickness of the three components of the complex were measured with calipers.
Results: The three components of the spring ligament complex are the superomedial calcaneonavicular ligament, the inferior calcaneonavicular ligament, and a structure that we termed the third ligament, which comprises fibers running from the notch between the calcaneal facets to the navicular tuberosity.
Conclusions: We demonstrated a third component of the spring ligament; this component runs from the notch between the anterior and middle calcaneal facets to the tubercle of the navicular in the lower layer of the spring ligament complex, lying beneath the cartilaginous surface of the complex.
Clinical Relevance: More accurate knowledge of the anatomy of the spring ligament complex will enhance our understanding of its role in the support of the head of the talus and, potentially, its critical interactions with the posterior tibial tendon in this regard.
The talocalcaneonavicular joint is a spheroid articulation comprising the head of the talus and the corresponding acetabulum pedis located at the distal end of the loading axis of the lower limb1. The acetabulum pedis is a complex joint consisting of the anterior and middle articular facets of the calcaneus, the talar articular surface of the navicular, and the spring ligament. The lateral and medial parts of the spring ligament are composed of the inferior calcaneonavicular ligament and the superomedial calcaneonavicular ligament, respectively2,3. The articular surface of the spring ligament is covered with fibrocartilage, creating an articular surface with the head of talus, termed the spring ligament fibrocartilage complex. There are no osseous supportive tissues in the calcaneonavicular region, so the talar head is supported by the spring ligament fibrocartilage complex and the posterior tibial tendon located beneath it.
When the spring ligament fibrocartilage complex ruptures, dysfunction of the...