The Delta Band | Ligaments of the ankle joint

The Delta Band

The deltoid ligament (“Ligamentum deltoideum” or also Ligamentum collaterale mediale) is, as the name suggests, a triangular band which is located on the inside of the ankle joint. It consists of four parts: Pars tibiotalaris anterior, pars tibiotalaris posterior, pars tibionavicularis, pars tibiocalcanea. All four parts of the ligament originate together from the inner ankle, which belongs to the shin bone.

From there they stretch like a fan to their starting points, the tarsal bones. Two of the ligaments, Pars tibiotalaris anterior and Pars tibiotalaris posterior, extend to the talus and end at the front and the back of the talus. The pars tibionavicularis ends at the scaphoid (Os naviculare), whereas the pars tibiocalcanea ends at the calcaneus.

Due to the closely connected course of the individual ligament components, a taut plate of extremely stable collagen fibres is formed. The deltoid, which is located at the inner ankle, has the primary task of preventing the foot from bending outwards (pronation). It also prevents the valgus position of the joint (joint malposition, in which the joint axis has a kink inwards).

Due to its nature, the delta strap contributes enormously to the stability of the entire ankle joint. This stability comes into play, among other things, when the foot comes into toe position (plantar flexion), since the bone guidance of the ankle joint is more unstable in this case. An injury to the stable deltoid ligament occurs very rarely.

Usually, the deltoid ligament is overstretched when the foot is bent outwards, as it is very tear-resistant. Nevertheless, the stability can be affected. A tear of the ligament or a part of the ligament during such a movement is very rare compared to the other ankle ligaments and is associated with great force being applied to the injury. If such an injury does occur, the joint and thus the deltoid ligament should first be relieved, splinted and then the load should be slowly increased. If this is not successful, a surgical procedure in which the ligament is sutured can be used to remedy the injury.

The Syndesmosis Band

Syndesmosis is a connective tissue ligament structure that holds two bones together and thus forms a fake joint, i.e. without a joint gap. This means that the bones – in the case of the tibia and fibula – are not freely movable against each other, which contributes to a certain stability. In the human body, there is such a syndesmosis, the “syndesmosis tibiofibularis”, between the lower parts of the tibia and fibula.

Thanks to this syndesmosis, the inner and outer malleoli form the so-called ankle fork, also called malleolar fork, which surrounds the ankle bone and thus forms the upper ankle joint. The syndesmosis consists of two strong ligaments, the anterior and posterior syndesmosis ligament. These ligaments are counted among those of the upper ankle joint.

However, both ligaments have their own special features. The anterior ligament of the syndesmosis has a slightly oblique course and runs from the outer part of the shin bone to the front edge of the fibula. The posterior syndesmosis ligament runs more horizontally from the posterior part of the fibula to the posterior and lateral part of the tibia.

The purpose of this syndesmosis is to ensure a certain stability in connection with the remaining ligaments of the ankle joint. With each step, this ligament structure is heavily loaded by both the body weight and the forces occurring during movement. Nevertheless, compared to the other ligaments, it is not as susceptible to injuries.

The reason for this is a connective tissue plate, which is stretched between the shinbone and the calf bone and thus, in addition to the syndesmosis, provides a high degree of stability. In addition, the ligaments of the syndesmosis limit this degree of movement due to their tension, which arises when the foot is pulled towards the tip of the nose. If the syndesmosis or the bony structure in the immediate vicinity is nevertheless injured by strong force, specific treatment is necessary to restore the degrees of movement and stability, which are of great importance. In addition, an injury to the syndesmosis can lead to minimal divergence of the ankle bifurcation, which, without immediate treatment, will result in increased joint wear.