Ankle Instability 

What is an ankle sprain?

Ligaments are strong, fibrous tissues that connect bones to other bones throughout the body. Numerous ligaments in the ankle help to keep the bones in proper position and stabilize the joint. Joint stability is important for all types of activities, including standing, walking, and running.

  • Around 90% of ankle sprains involve an inversion injury (the foot turns inward) to the anterior talofibular (ATFL) and calcaneofibular (CFL) ligaments — the lateral ligaments on the outside of the ankle. 
  • The less common medial ankle sprain is caused by an eversion injury (the foot turns out) to the deltoid ligament on the inside of the ankle. 

Sprains can range from tiny tears in the fibers that make up the ligament to complete tears.

If there is a complete tear of the ligaments, the ankle may become unstable after the initial injury phase passes. Over time, this instability can result in damage to the bones and cartilage, the smooth lining of the joint.

What are the symptoms of an ankle sprain?

The types and severity of symptoms for a sprained ankle vary widely depending on the degree of the injury. Symptoms may include:

  • Pain, both at rest and with weightbearing or activity
  • Swelling
  • Bruising
  • Tenderness to touch
  • Instability of the ankle, or feeling that your ankle is giving out

Symptoms of a severe sprain are similar to those of an ankle fracture (broken bone) and warrant X-Ray evaluation.

Do I need imaging?

An ankle sprain is largely a clinical diagnosis based on how the injury happened, symptoms, and examination by a medical professional. Occasionally, imaging studies, such as X-rays and magnetic resonance imaging (MRI) scans, are obtained to rule out a fracture or other injury to the nearby tendons and cartilage. 

X-rays. X-rays provide images of dense structures, such as bone. Depending on your symptoms and examination, your doctor may order X-rays to evaluate the bones in your ankle and foot. Severe ankle sprains can have a similar degree of pain, bruising, and swelling as a fracture, making it difficult to distinguish between the two. 

Stress X-rays. In addition to plain X-rays, your doctor may also order stress X-rays. These images are taken while the ankle is being pushed in different directions in a controlled manner. Stress X-rays help to show whether the ankle is unstable because of injured ligaments.

Magnetic resonance imaging (MRI) scan. An MRI scan is not required to diagnose ankle sprains. Your doctor may obtain an MRI:

  • To evaluate other structures, such as cartilage and tendons, around the ankle
  • If you exhibit signs of a high ankle sprain — an injury to the ligaments and structures connecting the bones of the lower leg (tibia and fibula)
  • If your symptoms persist beyond 6 to 8 weeks after the injury despite conservative treatment

How do I treat an ankle sprain?

Nonsurgical Treatment

Nearly all isolated low ankle sprains can be treated without surgery. Even a complete ligament tear (Grade 3) will heal without surgical repair if it is immobilized and rehabilitated appropriately.

A three-phase program guides treatment for all ankle sprains — from mild to severe:

Phase 1

  • Includes a short period of immobilization, rest, and ice to reduce the swelling.
  • Early weight bearing as tolerated is typically recommended during this phase.
  • For a Grade 2 sprain, a removable plastic device, such as a walking boot or aircast brace, can provide support.
  • Grade 3 sprains may require a short leg cast or cast-brace for 10 to 14 days.
  • In most cases, swelling and pain will last 2 to 3 days. Walking may be difficult during this time, and your doctor may recommend that you use crutches as needed.

Phase 2

  • Is typically initiated early and includes functional rehabilitation that focuses on:
    • Range of motion exercises
    • Isometric strengthening
    • Proprioception (balance) retraining exercises
  • It is important to discontinue ankle immobilization during this phase to avoid stiffness. 

Phase 3

  • Includes advancement of strengthening and proprioception exercises and the gradual return to pre-injury activities. This begins with activities that do not require turning or twisting the ankle, followed later by activities that require sharp, sudden turns (cutting activities), such as tennis, basketball, or football.
  • Early return to sporting and work activities may require ankle taping or bracing. 

This three-phase treatment program may take just 2 weeks to complete for minor sprains, or up to 6 to 12 weeks for more severe injuries.

The RICE protocol. Follow the RICE protocol as soon as possible after your injury:

  • Rest your ankle by not walking on it or returning to sport. 
  • Ice should be immediately applied to keep the swelling down. It can be used for 20 to 30 minutes, 3 or 4 times daily. Do not apply ice directly to your skin.
  • Compression dressings, bandages, or ace-wraps will immobilize and support your injured ankle. The compression may also help with swelling.
  • Elevate your ankle above the level of your heart as often as possible during the first 48 hours. Elevation also helps control the swelling.

Physical therapy. Rehabilitation exercises during phase 2 and 3 of recovery are used to improve flexibility, strength, and proprioception (balance).

  • Early motion. To prevent stiffness, your doctor or physical therapist will provide you with exercises that involve range-of-motion or controlled movements of your ankle without resistance.
  • Strengthening exercises. Once the swelling and pain have improved, exercises to strengthen the dynamic stabilizers (muscles and tendons) in the front and back of your leg and ankle will be added to your treatment plan. Water exercises may be used if weightbearing strengthening exercises, such as toe-raising, are too painful. Exercises with resistance are added as tolerated.
  • Proprioception (balance) training. Poor balance often leads to repeat sprains and ankle instability. A good example of a balance exercise is standing on the affected foot with the opposite foot raised and eyes closed. Balance boards are often used in this stage of rehabilitation.
  • Endurance and agility exercises. Once you are pain-free, other exercises, such as agility drills, may be added gradually. Running in progressively smaller figures-of-8 is excellent for agility and calf and ankle strength. The goal is to increase strength and range of motion as balance improves over time.

Surgical treatment for ankle sprains is rare.

  • Surgery is reserved for injuries that fail to respond to nonsurgical treatment, and for patients who experience persistent ankle instability and pain  after months of rehabilitation and nonsurgical treatment.
  • Surgery may also be indicated for some high ankle sprains with instability of the ankle syndesmosis.
  • Sometimes surgery is recommended if a severe ankle sprain is associated with additional injuries, such as an ankle cartilage injury or tendon rupture.