Chronic Ankle Instability (CAI)

As previously discussed in this article on Lateral Ankle Sprain (LAS), Chronic Ankle Instability (CAI) is something we need to guard ourselves against after an injury to the ligaments in our ankle complex. Few injuries are more frustrating than repetitive ankle sprains, and many athletes are losing vital training and match time, or perform below par due to heavy strappings and lack of “trust” with fear of the leg giving way. This article will discuss CAI, how to identify and to prevent it to give you the best chance of returning to an optimal, pain free level of function after complications in rehabilitation of a LAS.

What is Chronic Ankle Instability?

CAI is defined as a condition where the symptoms of ankle sprains persists for over 6 months after the initial injury. These symptoms are swelling, reduced strength, feeling of the leg giving away and reduced balance. Evidence suggest that up to 72% of people diagnosed with CAI were unable to return to their original level of function, and 85% developed symptoms in the non-affected leg. This highlights the importance of an early identification and risk prevention, especially in the high performing athlete group of patients.

Subgroups of Chronic Ankle Instability

There are 2 widely accepted subgroups of CAI, namely Functional Instability and Mechanical Instability. Individuals in the Functional Instability group typically present with recurrent ankle sprains and frequent sensations of instability, but tests negatively to changes in range of motion or ligament laxity. This diagnosis is based on the individual’s own, self-reported feeling of reduced function and instability. The other group, Mechanical Instability, presents with laxity in the ligaments around the ankle joint leading to vulnerability of recurring injuries.

How to identify Chronic Ankle Instability

Star Excursion Balance Test

In order to identify the risk of developing CAI, there are 3 factors commonly suggested to be of importance. First we will look at the jumping and landing strategies. Inability to preform jumping and landing tasks from as early as 2 weeks after sprains could indicate an increased risk of CAI. Poor performance in single leg balance tasks is the second sign we look for. This could be tested during the Star Excursion Balance Test or by measuring the time standing on a single leg without wobbling. The last factor is subjective, self-reported functions on the Foot and Ankle Ability Measure or on the Cumberland Instability Tool.

When assessing the possibility of developing CAI, like any other musceloskeletal or soft tissue injury, we have to look at a series of intrinsic and extrinsic risk factors. Advanced age, poor neuromuscular control and history of similar injury are intrinsic factors to take into consideration. These factors are for the most part hard to do anything about. The extrinsic factors such as specific sporting- or day to day activities could be avoided or amended to reduce the risk of recurrent injury.

How to prevent Chronic Ankle Instability

So from what we have learnt about CAI, there are a few prevention strategies to implement to avoid, or reduce, the long term effects after an ankle sprain. These are individual on a case to case basis, but in general aims to do the following.

• Strategies to avoid hypo- or hypermobility in the ankle joint
• Protecting the healing structures to prevent reoccurring, traumatic injury
• Correcting sensorimotor deficits and joint instability in lower limbs

Preventing either excessive or reduced ankle ranges are self-explanatory. You want a range in the ankle joints that is similar to the non-affected leg. Correction of hypomobility have some evidence of success through joint mobilisation. Hypermobility is corrected by an evaluation of the affected joints (ankle, knee and hip) and ties mostly in with protecting the structures in the healing phase, making sure the ligament is not losing its tensile strength during the repair. This is done through either bracing or strapping to mechanically reduce movements in the unfavourable directions (sole turning inwards and toes pointing down). Correction of the sensorimotor deficits and joint stability could only be done through a thorough examination of landing strategies, balance and proprioceptive control and muscle recruitment and is highly individual. It is also important to keep in mind that compensatory mechanisms could be present in hip, knee and in the non-affected leg and is not only found in the side of the ankle sprain.

Importance of early identification of intervention

So the conclusion is that early recognition of risk factors for developing CAI is crucial. Signs of CAI could be found as early as 2 weeks post ankle sprain and strategies should be put in place at this stage to prevent long term negative effects. Balance control and correct landing, running and jumping strategies are also useful tools in order to prevent recurrence of injuries.

Chris Smetana, MISCP