In a recent article, we discussed the general pathology surrounding medial ankle sprains, including mechanisms of injury, structures involved, and common approaches to treatment. As such, we touched on the main ligament involved in medial ankle sprains, which is the deltoid ligament.
Given the complexity of the deltoid ligament, we decided to discuss this structure in more detail in this article, ultimately allowing for a comprehensive understanding of its structure, function, and involvement in ankle injuries.
What is the deltoid ligament?
The deltoid ligament is a group of ligaments on the medial aspect of the ankle, which is the inside part of the ankle. When these ligaments are pictured together, it’s very wide and fan-shaped complex, and it can be hard to distinguish the individual ligaments that make up the deltoid ligament complex.
Anatomy of the Deltoid Ligament
All the ligaments that form the deltoid ligament complex provide passive support to the inside of the ankle, which you may also hear called the medial aspect of the ankle (medial = inside, lateral = outside).
Passive support means the ligaments cannot be actively contracted like muscles, so you can almost picture a thick elastic band, but this thick fibrous ligament tissue can still provide ample support, especially in combination with surrounding musculature.
When we look at the ligament in more detail, it’s actually surprisingly complex, and can be categorized into two layers: the superficial layer, and the deep layer, with multiple bands in each layer. We will discuss these layers in detail, which will involve diving into the nitty-gritty of the medial ankle bone and ligament anatomy.
Therefore, we will first take a look at the bones in the medial ankle and foot region, as these will be the attachment sites for the different bands of the deltoid ligament.
Medial Ankle and Foot Bones
Before diving into the specifics about the deltoid ligament complex itself, it can often help to have a sense of the associated skeletal anatomy as well. After all, ligaments serve to connect bone to bone, ultimately stabilizing that articulation and forming a well-supported joint.
Having a sense of the attachment sites can make understanding the function of the deltoid ligament a little easier.
Superficial and Deep Layers of the Deltoid Ligament
Superficial Layer of the Deltoid Ligament
Tibiocalcaneal Ligament
Origin: Medial malleolus of the tibia
Insertion: Sustentaculum tali of the calcaneus
Function: Resists forced ankle eversion especially in dorsiflexed positions
Tibionavicular Ligament
*** Some recent literature, for example Gregerson et al (2022), suggest the tibionavicular ligament not be considered a completely distinct ligament of the deltoid complex given the difficulty in distinguishing its fibers from the joint capsule in cadaveric studies.
Origin: Medial malleolus of the tibia
Insertion: Navicular tuberosity
Function: Resists forced eversion, helps to suspend the spring ligament, and assists in stabilizing the head of the talus
Posterior Superficial Tibiotalar Ligament
Origin: Medial malleolus of the tibia
Insertion: Posterior process (medial tubercle) of the talus
Function: Resists forced eversion and excessive valgus movement of the ankle
Tibiospring Ligament
*** The tibiospring ligament is somewhat controversial in that it’s not always considered to be a part of the deltoid ligament specifically.
Origin: Medial malleolus of the tibia
Insertion: Spring ligament
Function: Resists forced eversion, particularly in a plantarflexed position, and provides support to the spring ligament, the latter of which helps to stabilize the medial longitudinal arch of the foot.
Deep Layer of the Deltoid Ligament
Anterior Tibiotalar Ligament
Origin: Medial malleolus of the tibia
Insertion: Proximal medial body of the talus
Function: Resists forced ankle eversion and rotation, particularly in a plantarflexed position.
Posterior Deep Tibiotalar Ligaments
*** In some resources, this ligament is not denoted to a specific compartment, as it can be considered part of the Posterior Superficial Tibiotalar Ligament.
Origin: Medial malleolus of the tibia
Insertion: Superior/posterior/medial aspect of the talus
Function: Provides medial ankle stability in dorsiflexed positions
Function of the Deltoid Ligament
As we eluded to previously, the deltoid ligament is meant to provide stability to the medial aspect of the foot and ankle. An easy way to think about it is a layering of tight and thick elastic bands covering the inside of the ankle.
This will make it more difficult to open up the joints on the medial aspect of the foot and ankle, thus allowing the foot and ankle to maintain a solid functional position.
Without the deltoid ligament, the inside of the ankle would be much less stable, which would make the ankle much more prone to injury, and even in the absence of injury, would reduce overall function especially in the sense of balance and coordination.
This would lead to an increased and disproportionate distribution of pressure to the joints of the medial foot and ankle.
How do you injure the deltoid ligament?
The mechanism of injury for a deltoid ligament sprain is typically forced ankle eversion, which is the opposite of the classic inversion ankle sprain. This is a fairly awkward movement, and generally speaking, occurs less, and therefore these medial ligaments are injured less than the lateral ankle ligaments. Nonetheless, deltoid ligament injuries still happen, especially in field sports or contact sports.
Forced eversion means the inside of the ankle is stretched out, or “opens up”, beyond the capabiltiies that this medial ankle ligament complex can resist.
Fortunately, there are muscles that span over the medial aspect of the foot and ankle, and other muscles that indirectly provide support to the ankle as a whole, and as such, the ligament really represents the last line of defence for the medial ankle.
Examples of situations that can lead to a deltoid ligament sprain include slipping on a step or curb where the inside of the foot rapidly drops down with the outside of the foot still planted. Another example could include jumping or running forwards and planting the foot with the inside of the ankle facing forwards.
Abrupt contact or trauma can also injure the deltoid ligament, such as sustaining an impact to the outside of the ankle with the foot planted (e.g. a slide tackle in soccer), or another player landing on the outside of the ankle while the foot is planted.
Who is at risk of a deltoid ligament sprain?
Given the awkward and/or traumatic nature of deltoid ligament sprains, these types of injuries are more likely to occur in the athletic population. According to a study conducted by Kopec et al (2013), the highest rates of deltoid ligament sprains occurred in women’s gymnastics, men’s and women’s soccer, and men’s football.
These represent high-impact, change of direction, and sometimes contact sports, which is consistent with what we would expect for these injuries. The authors also pointed out that physical contact with an opponent was the most common mechanism for the deltoid ligament sprains that they examined.
While this study did examine 380 different instances of deltoid ligament sprains, it’s worth keeping in mind that this is one single study investigating a focused population of collegiate athletes. Nevertheless, this provides some insight into the rate and common settings for deltoid ligament injuries.
Treatment for a Deltoid Ligament Sprain
The general approach to treatment for a deltoid ligament injury has been discussed more comprehensively in our medial ankle sprain article, so we will cover the basics here, highlighting how a deltoid ligament injury may differ from a lateral ankle sprain, which is the more common type of low ankle sprain.
First, if the deltoid ligament or any medial ankle ligaments become structurally damaged, the body will initiate the inflammatory phase of healing. Inflammation is often considered a bad thing, but in reality, this is a necessary phase of healing and is required to provide a clean slate for the deposition and subsequent remodelling of new healthy ligament tissue.
During the inflammatory phase of healing after a deltoid ligament sprain, it’s important to protect all of these medial ankle ligaments, which can range from general caution with movement to immobilization in a lace-up ankle brace or walking boot.
The R.I.C.E. principle is often applied here as well, whereby rest, ice, compression, and elevation can all help reduce symptoms, provide an optimal environment for healing, and prevent secondary tissue damage from excessive swelling.
After ~ 1-2 weeks, these ligaments will start transitioning into the proliferative phase of healing, which in the simplest terms, involves the deposition of new healthy tissue to repair the damaged ligaments.
During this phase, your physiotherapist may recommend more range of motion and basic strengthening exercises depending on the extent of your injury and recovery thus far.
In terms of range of motion, one movement that is typically avoided, or at least not forced, is ankle eversion. An easy way to remember this is that it’s the same movement that likely contributed to the damage of the medial ankle ligaments.
While it’s a normal movement that a healthy ankle should be able to perform, stretching into this motion too soon can potentially prevent the ligaments from healing in a taut manner. The more laxity in the ligaments (laxity = “looseness”), the less stability they will provide to the ankle joint.
When it comes to strengthening, all muscles around the foot and ankle will require improving or maintaining strength. There may be a particular focus on muscle that help prevent excessive eversion of the ankle, such as tibialis posterior, which plays a crucial roll in foot and ankle stability, but has the ability to actively invert the ankle, thus resisting forced eversion.
Other assisting muscles that help stabilize the medial aspect of the foot and ankle, such as flexor digitorum longus and tibialis anterior, may also be prioritized for strengthening. Flexor digitorum longus helps provide support to the medial aspect of the ankle and sole of the foot, and when contracted, will serve to flex the big toe.
The main action of tibialis anterior is ankle dorsiflexion (bringing your foot up, or “toes to nose”), whereas tibialis posterior will help with plantarflexion (pointing the toes down, or “pressing the gas peddle”).
However, they are similar in the sense that they both assist with ankle inversion and they both insert on the medial aspect of the foot, thus helping prevent excessive ankle eversion and providing protection to the deltoid ligament complex.
Finally, the advanced phase of rehab usually occurs during the remodelling phase of tissue healing, which can start as early as 2-3 weeks post-injury, and may last as long as 2 years.
In this phase, the healed ligament is progressively stressed so that it continues to remodel itself according to the demands on the ankle.
Another way to look at this is the ligament is trying to figure out how to organize itself on a micro-scale in order to be the strongest it can be based on the forces that are most commonly placed on it.
For both recreational and competitive athletes, return-to-sport rehab is often recommended before going back into a game 100%.
Your physiotherapist will be an expert in guiding this stage of rehab as well, as they can provide clever exercises that facilitate gameplay while keep a specific focus on treating the deltoid ligament.
These exercises may require fast movements (reaction time), jumping or other impact loading (high rate of loading), and multi-joint dynamic exercises to further challenge proprioception and coordination.
Summary
The deltoid ligament complex is a group of medial ankle ligaments found on the inside of the ankle. These ligaments can be injured through forced excessive ankle eversion, which can occur in day-to-day setting, as well as high level sports.
Rehab for a medial ankle sprain is very similar to that of a lateral ankle sprain, just with some key considerations that will help provide safe and effective rehab.
In order to confidently rehab a deltoid ligament sprain, it’s important to consult with a physiotherapist, as they will be able to guide you through the subtleties of a deltoid ligament sprain, allowing you to manage your own injury in a safe, effective, and confident manner.
References
Gregersen MG, Fagerhaug Dalen A, Nilsen F, Molund M. The Anatomy and Function of the Individual Bands of the Deltoid Ligament—and Implications for Stability Assessment of SER Ankle Fractures. Foot & Ankle Orthopaedics. 2022;7(2). doi:10.1177/24730114221104078.
McCollum, G. A., van den Bekerom, M. P., Kerkhoffs, G. M., Calder, J. D., & van Dijk, C. N. (2013). Syndesmosis and deltoid ligament injuries in the athlete. Knee Surgery, Sports Traumatology, Arthroscopy, 21, 1328-1337.
Disclaimer:
The content here is designed for information & education purposes only and is not intended for medical advice.
