Ankle Instability

Do you suffer from chronic ankle sprains or “Weak Ankles”? In this section, Cypress Foot and Ankle specialist Dr. Christopher Correa discusses ankle instability, which is a common cause of repeated ankle sprains. “Weak ankles” is a colloquial term for ankle instability. Ankle instability is the incompetence of the medial and lateral supporting ligaments and tendons. This leads to a failure to maintain proper joint alignment when challenged with an external force. Instability can occur on either side of the ankle, though medial ankle instability occurs far less commonly than lateral ankle instability. While lasting instability does not occur after most ankle sprains, there is a 10-15% chance after each ankle sprain that a ligamentous incompetency or a functional deficiency will persist. The more frequent and severe an ankle sprain is, the more likely there will be a lasting issue. While the vast majority of ankle sprains heal with no need for advanced medical evaluation or treatment, any ankle problem that persists 4-6 weeks after the injury should be evaluated by a professional.

Ankle rehabilitation

Patients with instability often complain of generalized ankle pain with activity, frequent ankle sprains, ankle swelling, weakness, and pain with wearing heels or heeled shoes. They often report difficulty walking on uneven ground such as grass, gravel, parking lots, or hiking trails, pain with cutting or quick changes in direction, or when walking down stairs or a decline. One may also report “painless ankle sprains,” where an ankle is twisted so frequently that the ligaments are replaced with scar tissue. The tearing of scar tissue during these events, if it occurs at all, causes minimal new damage and inflammation. With no lasting pain or inflammation, the event is viewed more as “missing a step” or “tweaking” instead of a full-blown sprain. It should be noted that this sort of chronic instability can lead to long-term attenuation and damage to tendons and joint capsules. This low-level damage can accumulate over time, leading to persistent swelling, pain, and disability. Furthermore, a "misstep" can be the inciting incident that leads to a fall, causing a broken ankle, wrist, elbow, or other body part.

Types of Lateral Ankle Instability

There are two categories of lateral ankle instability: structural and functional. Functional ankle instability occurs when the ligaments and support structures are not actually damaged and can still maintain normal alignment of the ankle. The instability usually comes from weakness and damage to the tendons or a delayed neuromuscular response to a stretch stimulus due to a non-functioning neurofeedback loop. Within the ligaments, there are nerve cells that function as stretch receptors. When these stretch receptors are activated, it triggers a neuro reflex that tells the body to compensate by firing the necessary muscles to counteract the stress. If these cells are damaged, the signal is either sent late or never sent. As a result, the ankle continues fall into a position of mechanical disadvantage until the motion can simply not be stopped, regardless of how hard the muscle pulls. If the compensating muscle pulls hard enough, it can lead to an avulsion fracture where the tendon pulls so hard it tears off the insertion, taking some bone with it. If the supporting ligaments are intact, then often strengthening, balance, and neuro-muscular re-education by a physical therapist can help improve symptoms.

Structural instability occurs when the supporting ligaments are damaged and no longer prevent the ankle bones from falling out of alignment when stressed. Ligaments can be partially or completely torn and typically occur after a single severe sprain that leads to swelling and bruising around the anterior lateral ankle. While the instability may not be apparent initially, as the swelling diminishes, lasting “weakness” and instability may show weeks later. While structural instability can be managed with bracing and physical therapy, it oftentimes requires operative intervention to repair and reinforce the damaged structures. Due to the compensation of the surrounding structures to counteract the instability, long-term untreated lateral ankle instability can lead to attenuation and tearing of the peroneal tendons, worsening overall pain and disability. Distinguishing between the two types of instability requires a manual examination by a trained practitioner and ideally a series of stress x-rays to see if any joint subluxation occurs. If left untreated, both forms of instability can lead to long-term damage to the peroneal tendons, contributing to continuous worsening pain as time goes on.

Normal ankle X- Ray

Unstable ankle

Treatments for Lateral Ankle Instability

Treatments for lateral ankle instability include physical therapy, bracing, NSAIDs, and sometimes surgical reconstruction of damaged ligaments. The success of conservative therapy depends on the type of lateral ankle instability and whether or not the patient is still participating in the types of activity that aggravate the ankle. If you are no longer participating in athletics or hiking, an underlying instability may not be severe enough to cause symptoms very often when compared to someone who participates in sports regularly. If you suffer from chronic ankle pain or frequent ankle sprains, consider having the professionals at Select Foot and Ankle Specialists evaluate your ankle for instability and take the first step towards recovery today.