Ankle sprains account for 12% of sports injuries in schools and 11% of all football injuries. While the majority of ankle sprains recover without long-term implications, up to 30% give rise to residual pain, and 20% result in an unstable ankle.
The Anatomy and Mechanics of an Ankle Sprain
An inversion injury is the most common mechanism by which an ankle is sprained. In this situation, the ankle rolls inwards while the toes are pointed downwards towards the ground. In a mild injury, ligaments are stretched but not torn. In more severe inversion ankle sprain, the most commonly torn ligament is the anterior talofibular ligament or ATFL. In addition, the calcaneofibular ligament or CFL may also be torn.
The most commonly understood function of a ligament is to keep the joint stable (mechanical function). The ligament prevents the joint from moving in directions it is not designed to, and also keeps the range of motion of the joint within normal limits. What is less commonly appreciated is that the ligament also has a sensory function. In the example of an ankle, as the ankle starts to roll over, the ligament tightens and nerve signals are sent to the nervous system to alert it that an ankle sprain is about to occur. Nerve impulses are then sent to the appropriate muscles (peroneal muscles) to contract, in order to prevent an ankle sprain.
Unlike some ligaments of the knee which have no ability to heal, ankle ligament tears do routinely heal.
However, healing usually results in a ligament which is elongated and too lax to serve its mechanical function effectively.
The sensory function is also impaired resulting in disruption of the ligament.
Treatment for an Ankle Sprain
With an inversion as a mechanism of injury, besides an ankle ligament injury, fractures around the ankle or foot may also result. When a healthcare professional is consulted after an ankle sprain, he or she will assess for the likelihood of a fracture and if this is suspected, X-rays may be necessary.
Once it has been ascertained that the sprain has resulted only in a ligament injury, immediate treatment is with RICE therapy:
These measures reduce swelling and inflammation at the injury site. Early return to daily activity has been found to reduce the duration of rehabilitation necessary before resumption of sports. As such, unless pain and swelling preclude walking, immobilisation in a case and the use of crutches is usually avoided.
Once initial pain and swelling has been managed, rehabilitation with physiotherapy will begin. Bearing in mind the mechanical and sensory function of ankle ligaments, physiotherapy focuses on restoring these. For the mechanical function, strengthening of the peroneal muscles allows to compensate for lax ankle ligaments. In order to restore the sensory function, balance training is insituted.
Once satisfactory rehabilitation has been achieved, return to sports with a brace or ankle taping is allows. The function of the brace or tape is two-fold. Firstly, these devices prevent the ankle from excessive range of motion which may predispose to an ankle sprain. The second role is to augment the sensory function of the ankle ligaments. Information regarding the position of the ankle is transmitted to the nervous system through the skin as the brace or tape heightens the skin’s ability so sense ankle motion as different areas tighten with different ankle positions.
Approximately 80% of people who suffer ankle sprains return to their chosen sport at the preinjury level. The remaining 20% continue to have ankle instability and suffer frequent sprains despite adequate physiotherapy. This group would benefit from ankle ligament reconstruction (ankle stabilisation).
Ankle Ligament Reconstruction
Many different methods have been described for ankle ligament reconstruction. The method usually employed is termed an “anatomic reconstruction” as it recreates the position of the native ATFL and CFL, usually using the actual ligaments themselves. This method gives the best outcome in terms of ankle stability and ability to return to sports.
Recalling how ankle ligaments heal in an elongated fashion, surgery aims to shorten the ligaments to the original length.
The stretched-out ligament is divided in the mid-portion and stitched in a shortened position with the ends overlapping each other.
After surgery, the ankle is protected first in a plaster cast then a walking boot for a total of six weeks. This is the time it takes the shortened ligament to heal. Following this, physiotherapy is started with a protocol similar to that of an ankle sprain to restore the mechanical and sensory function of the ankle. Return to sports is expected, usually, in three months.
The majority of ankle sprains recover without long-term consequences. Some persist to give chronic ankle instability and recurrent sprains. For this group, ankle ligament reconstruction is an effective method of stabilising the ankle to allow return to sport.
- Tape or brace an ankle that has recovered from an ankle sprain or return to sport as this reduces the risk of further injuries.
- Seek medial attention for an ankle that is unstable or if you experience frequent ankle sprains. Recurrent ankle sprains may result in cartilage damage, which is a precursor to ankle arthritis.
- Ignore a severe ankle sprain especially if walking is difficult. It could be an indication of a problem more severe than a ligament tear, for example an ankle fracture.
- Resume sports without adequate recovery and rehabilitation following an ankle sprain. This could lead to long-term problems such as pain and recurrent sprains.