When you sprain your ankle, most people assume they’ve just torn some ligaments. But there’s so much more that can go wrong and delay your recovery. Read on to understand why your ankle sprain may not be getting better…
WHAT HAPPENS WHEN YOU SPRAIN YOUR ANKLE?
THE ANATOMY OF THE ANKLE
Firstly you’ll need to visualise the design of the ankle joint. It’s essentially a square-shaped bone (the Talus) sitting in a square-shaped space (formed by the Tibia and Fibula).
The main function of this joint is forward/backward movement (known as Plantarflexion and Dorsiflexion). There’s a little bit of room on either side of the joint which accommodates some sideways tilting as well.
Where the bones touch, they have a smooth surface (joint cartilage) designed to allow easy movement under load.
Holding all that together is a wall of connective tissue surrounding the whole joint (the joint capsule). That capsule has a sensitive, water-tight lining (known as the synovium).
Bracing that capsule is a number of ligaments, strong bands of connective tissue that connect bone to bone and restrain movement.
THE ACTION OF SPRAINING AN ANKLE
When the ankle rolls, the square bone rotates inside the square joint space. That potentially causes bones to bump into each other. As it rolls, it rapidly stretches the joint capsule, its sensitive lining and the bracing ligaments.
The most commonly known injury from an ankle sprain is a torn ligament. This usually involves ATFL (Anterior Talofibular Ligament) and CFL (Calcaneofibular Ligament) on the outside of the ankle. They are the primary restraints of that movement and the first to go.
After each sprain, the ligaments recover but they don’t heal back to 100% capacity. You’ll likely get about 50-70% of their pre-injury function.
So with each subsequent sprain, the primary restraints are less capable and the rest of the joint structures may take some of the sudden overload. This can also happen in a first time sprain but it takes a lot more force.
If the primary ligaments don’t effectively restrain the joint, the bones bump into each other. This creates a bone oedema (aka. bone bruise), much like a kick in the shin. This causes swelling inside the joint and a constant dull ache with prolonged activity.
The joint capsule will also overstretch, along with its sensitive joint lining. The capsule is typically undamaged but the lining reacts, creating an inflammatory response (known as synovitis) that is painful to stretch or compress.
As the joint surfaces moved rapidly off alignment, the smooth cartilage can be bruised or gouged. This creates bone bruising and swelling inside the joint, which further stretches and aggravates the joint lining.
Joint cartilage damage occurs in around 7%, or 1 in 14, ankle sprains.
With strong force of the bones that form the square space over the ankle, the bones can get forced apart, damaging the ligaments above the ankle. If the ligaments hold, the bone on the outside of the ankle may fracture.
Here’s a list of injuries that can occur with an ankle sprain.
|Simple ligament damage after rolling an ankle, causes bruising and swelling||Ankle ligament injury|
|Cartilage damage inside the ankle causing recurrent swelling and a deep ache on weight bearing||Talar dome lesion|
|A reaction around the joint, it causes sharp pain and ongoing ache. It doesn’t like stretching or compression||Joint capsule reaction|
|Impact to the bones inside the ankle, this is felt as a deep ache and some swelling||Bone oedema (aka “kissing lesion”)|
|Damage to the ligament/s above the ankle joint, this causes pain with dorsiflexion (knee moving forwards)||Syndesmosis injury|
|A complication of a sprain, the bone on the outside of the ankle can fracture||Fibula fracture|
|The soft tissue or bones around the joint can pinch together on movement, causing a sharp pain and residual ache||Talocrural (ankle) impingement|
|The joint below the main ankle joint, it’s often strained in the same incident and causes pain on impact or uneven ground||Subtalar joint irritation|