The ankle is a hinge joint between the leg and the foot, and allows up and down movement. The bones of the leg (tibia and fibula) form a slot, and the talus bone of the foot fits between them. The talus is held to the tibia and fibula by strong bands of tissue called ligaments.
The ligament on the inside of the ankle (the deltoid ligament) has two layers; the deepest one is most important. The ligament on the outside of the ankle (lateral ligament) is made up of three separate bands: one at the front (anterior talo-fibular ligament), one in the middle (calcanei-fibular ligament) and one at the back (posterior talo-fibular ligament). The front and middle bands are the ligaments injured in a sprain.
The tibia and fibula form a joint between themselves just above the ankle. This also has strong ligaments, one at the front and one at the back (tibio-fibular ligaments).
The ligament at the front is involved in 10-20% of ankle sprains; this injury is important, as it takes a long time to heal, although it usually heals without the need for surgical treatment.
Most ankle ligament injuries are caused when the foot twists inwards. All of the body’s weight is then placed on the lateral ankle ligaments. The anterior and middle fibres of the ankle stretch or tear a in sprain or strain of the ankle. Occasionally small pieces of bone may be torn off with the ligaments.
In a few cases, a twisting force on the ankle may cause other damage. The bones around the ankle may be broken, a piece of the cartilage lining the ankle may be chipped off, ligaments connecting other bones in the foot may be sprained or torn, or the tendons around the ankle may be damaged.
Most ankle sprains are fairly minor injuries, which will get better with simple self-care treatment.
SYMPTOMS
Why Ankle Instability?
The majority of ankle injuries get better completely and cause no long-term problems. Unfortunately occasionally there is permanent damage to the ankle. The ligaments may fail to heal properly and become weak – leading to ankle instability, or there may be damage to the joint itself or some other structure nearby – leading to ankle pain and swelling.
Diagnosis of Ankle Instability
Doctor will listen to your complaints about your ankle and examine you. They will look for any sign that you have some other problem around your ankle, such as damage to the joint surface. They will stretch your ankle to see if the ligaments are abnormally weak. An X-ray will usually be taken to see if there is any damage to the bones of your ankle. Ligaments do not show on X-rays. Ligament damage can be shown by taking X-rays with your ankle stretched in various directions (“stress views”) or with a magnetic (MRI) scan.
MANAGEMENT
Most people with ankle ligament instability have damage to the ligaments, which can be overcome with appropriate physiotherapy rehabilitation. The rehabilitation concentrates on two main areas. Firstly strengthening the muscles around the outside of the ankle. Secondly, by improving your balance. This may require the use of specialized equipment such as a “wobble-board,” or a “trampette.”
If your ankle or Achilles tendon are stiff, you will also be shown exercises to stretch these. If your foot shape makes you prone to extra stress on the ankle ligaments, a moulded insole may be advised for your shoe to reduce these stresses.
Most people will find their ankle much more stable and comfortable after physiotherapy. However, in some people problems continue.
SURGERY
Most people with ankle instability will not need an operation. Even if your ankle still feels unstable after physiotherapy, you could try a brace rather than having an operation to tighten up or replace the ligaments.
However, if no other treatment makes your ankle comfortable and tests show that the ligaments are weak, an operation may help. There are two main types of operation:
Following surgery you will be in plaster for six weeks. After this you need to wear an ankle brace for a further 6 weeks. Physiotherapy treatment is usually required.
You can start light exercise at 3 months, but sport involving twisting are not allowed until 6 months after the surgery.