The knee joint is the articulation between the tibia (shinbone) and the talus. The main motion is flexion upwards (dorsiflexion) and downwards (plantarflexion). 
With weight-bearing approximately the ankle joint is exposed to forces equivalent to 5 times body weight. On the lateral aspect the primary ligaments for stabilization are the anterior and posterior talofibular (ATFL and PTFL) and calcaneofibular ligament (CFL).
The syndesmosis connects the fibula and tibia. The syndesmosis is an important structure and is responsible for the integrity of the ankle joint.
On the medial aspect the deltoid ligament and spring ligament stabilize the joint. The ATFL resists inversion in plantarflexion and is the weakest of the lateral ligaments. It is most commonly involved in ankle sprains. The CFL restricts inversion in the neutral or dorsiflexed position. The deltoid ligament restricts outward movement (valgus) of the ankle joint. It has a deep and superficial component; the deep component is the primary medial stabilizer. 
The spring ligament stabilizes the medial foot arch.
