Unstable Ankle Fracture
Edited by Michael Castro, DO
An unstable ankle fracture can occur when an injury compromises the integrity or stability of the ankle joint. The fracture may involve the ligaments that hold the joint together, the joint surfaces themselves or a combination of both. In an unstable ankle fracture, the joint will not support weight-bearing without displacing. These injuries can result from any number of traumatic causes from a twisting injury to a car accident. Immediate medical attention is necessary to assess the extent of the injuries including any associated skin wounds, the extent of any deformity, and the impairment of sensation and circulation. Most commonly, unstable fractures of the ankle require surgery to restore the anatomy and stabilize the injury
The mechanism of injury varies, although it often involves some type of twisting injury to the ankle. This type of injury may occur by stepping awkwardly and twisting when walking down steps or stepping off of a curb. These injuries may also occur while participating in sports and recreational activities. Higher energy injuries such as falling from a height or being involved in a motor vehicle accidents are also common causes of unstable ankle fractures. These injuries result in marked pain and almost immediate swelling of the ankle. There may be an obvious deformity present regardless of the mechanism. A deformity may just as likely occur in association with a motor vehicle as with a misstep off a curb. With few exceptions, bearing weight on the limb is not possible due to pain. An attempt to weight-bear should be avoided if at all possible. In extreme cases there may be an associated skin wound caused by tension or the underlying bone. This type of wound often represents an open fracture as the fracture communicates with the outside world thereby increasing the chance of infection and demanding urgent treatment. Patients may also experience numbness or tingling in the case of nerve injury. There may also be discoloration of the foot if blood flow is interrupted. As a rule, this type of injury requires immediate care and medical attention. It is important to identify any associated skin wounds, the extent of any deformity and any impairment of sensation and circulation.
Initial management of the fracture begins at the scene of the injury. The leg should be immobilized, usually with some type of splint. Immobilizing the leg, ankle and foot can provide comfort and prevent further injury. The immediate application of ice can also help with pain and slow swelling. Transport to a hospital emergency room should be done quickly and safely. If safe transport is unavailable, emergency medical services should be contacted. Emergency Medical Technicians (EMT’s) are experts in the initial assessment and stabilization of these injuries.
Upon arrival to the emergency department, the injury is again assessed. The condition of the skin, nerve function and circulation are evaluated. X-rays will be obtained to appreciate the bony detail of the injury. However, for grossly displaced fractures it is often beneficial for the ankle joint to be repositioned (reduced) before the x-rays are taken. Following x-rays, a decision point is reached. Once the ankle is aligned and stabilized, or in the absence of deformity or “open” injury, the patient is immobilized. A well-padded splint is applied. A splint is preferred to a cast as a splint allows for swelling where a cast does not. Swelling with a cast in place may cause problems with circulation. Crutches are provided to help avoid weight bearing on the injured limb. Arrangements can be made for a knee scooter, walker or wheelchair if necessary. The patient may be discharged home with pain medications and instructions for elevating and icing. Follow up with an orthopedic surgeon should be arranged in the near future. It is important for the patient to be evaluated sooner rather than later to determine if surgery is necessary and when it should be scheduled. In addition, the orthopedic surgeon may recommend further imaging if not already performed at the time of the emergency room visit,
There may be occasions where patients medical conditions prevent the individual from having surgery. In some instances, it may be necessary to treat an unstable ankle fracture non-operatively. However, this situation is rare and must be evaluated on an individual basis.
Dislocation of the Ankle
If the ankle is dislocated it will be necessary for a physician to realign or reduce the deformity. Dislocation is the dissociation or separation of the bones that make up the joint where they are no longer in contact as a result of the injury. Reduction of a dislocated ankle joint is an urgent priority and usually performed in the emergency department. Reducing a dislocated ankle fracture is performed using some combination of sedation, pain medication, muscle relaxers, and local anesthetics depending on the emergency room physician’s assessment of the patient. Once the patient is comfortable, gentle traction is applied and the joint is realigned.
If the deformity cannot be corrected by these means, the patient may require urgent surgery to reduce the joint or realign the limb. If the fracture and/or dislocation is grossly unstable, an external fixator may need to be applied. External fixation is a means of rigidly stabilizing an unstable fracture and/or dislocation. External fixation consists of placing pins into the bone above and below the fracture of unstable joint. The pins are placed through small incisions, they protrude from the skin and are spanned by a bar.
Open Ankle Fracture
Another reason for urgent operative treatment is in the event that a fracture fragment has broken through the skin, referred to as an “open fracture.” Open fractures require urgent surgery to washout the wound and minimize the chance of infection. The size and location of the wound will determine the next step. If the wound is small, simply washing is out, dressing it and applying a splint may be appropriate. If, in addition to being open there is gross instability an external fixator may be applied. In the case of a large wound that can be adequately washed out, the fracture may be stabilized with plates and screws at that time. If the wound is a result of a high energy mechanism (car accident, fall from height, etc.) or is badly contaminated, meaning dirt or other material from the environment ended up in the wound a second look at the wound and wash out may be necessary before fixation is finalized. This usually requires the patient to stay in the hospital returning to the operating room 48 hours later.
The focus of surgical management of unstable ankle fractures is restoring the relationship of the joint surfaces, correcting alignment and stabilizing the fracture, usually with plates and screws, referred to as rigid internal fixation. The goal of rigid internal fixation is to stabilize the fracture allowing early motion of the involved joint(s). Early motion, usually after the incision(s) is/are healed (~2 weeks) can avoid the joint stiffness, muscle atrophy (shrinkage), nerve and skin changes that can result from long-term immobilization referred to as “fracture disease.” Avoiding or minimizing these changes can streamline the rehab process and restore normal function more efficiently.
Follow up with an orthopedic surgeon should be scheduled for within 2 to 3 days of the injury to address timing of surgery and any specific patient needs. The timing of surgical treatment is very important and depends on a number of factors, the most important of which is swelling. Unstable ankle fractures tend to swell quite a bit. It is important to think of the focus of the initial phase of treatment as the control of swelling. This is best accomplished by avoiding weight-bearing and keeping the injured foot/ankle elevated above the level of the heart with the exception of getting up to eat or use the bathroom. Surgery is usually delayed until swelling resolves sufficiently to perform surgery safely. Operating before swelling resolves sufficiently can increase the risk of wound problems leading to infection.
Patients undergoing surgical management of an unstable ankle fracture usually require a minimum of 6 weeks non-weight-bearing in some form of immobilization. This may be a cast, a splint, or removable boot. Depending on physical examination and x-ray findings at 6 to 8 weeks, progressive weight-bearing may begin. Weight starts in a boot and transitions to an athletic-type brace, allowing more normal-appearing walking. Once crutches are no longer needed, more aggressive therapy begins in the “rehabilitation phase”. Physical therapy focuses on restoring ankle motion, strength and balance, or the bodies protective reflexes referred to as proprioception. Use of the brace continues until strength and balance improve. It is common for it to take six months (or more) for patients to feel comfortable performing basic everyday activities (walking a number of blocks, standing for prolonged periods, basic sporting activities, etc.) It can be a total of 12-18 months for complete recovery.
The main potential complication that is specific to an unstable ankle fracture is the potential for traumatic ankle arthritis. A previous ankle fracture may increase the risk of ankle arthritis. However, the key determinants influencing arthritis are cartilage damage occurring at the time of the original injury, the accuracy with which the joint surface was restored at surgery and the restoration of joint motion, muscle strength and proprioception during therapy.
Other potential complications involving this type of surgery:
- Wound healing problems
- Nerve injury
- Deep Vein Thrombosis (DVT)
- Pulmonary Embolism
Edited May 31, 2020
Previously edited by Michael Shereff, MD