Bimalleolar ankle fracture is a fracture that occurs in both the lateral and medial malleoli at the distal end of the tibia and fibula bones that articulate with talus bone to form the ankle joint or tibiotalar joint. This joint is in the mortise and tenon joint classification. It is supported by ligaments to stabilize the talus under the tibia and the tibia with the fibula. This type of fracture often affects these ligaments.
These crucial ligaments include the syndesmotic ligaments that stabilize the fibula within the incisura in the tibial bone, and another critical ligament is the deltoid complex ligament, which is a broad ligament with a fan-like structure that originates from the medial malleolar to insert in the talus bone; it also subdivides into two ligaments. The most common ligament injury or cut is the deltoid ligament (medial ligamentous) during the medial malleolar fracture, causing joint instability. Bimalleolar ankle fracture is caused by twisting with multiple force mechanisms, or supination injury.
The most common mechanism that cuts this ligament is foot eversion or external rotation force. Conversely, in the inversion mechanism, the primary ligament injured is the anterior talofibular ligament, and hyper-dorsiflexion trauma might cause syndesmotic ligament tears or sprains. According to the Lauge-Hansen and the Weber classifications, this fracture is unstable, and it classifies as Supination-External Rotation Injuries III, V (Weber Type B) that requires operative intervention. This fracture can lead to disabling long term sequelae following treatment, making this type of fracture have a poor prognosis.
According to the Lauge Hansen classification: supination and external rotation injury are the most common cause of bimalleolar fractures. Eversion is considered the most common reason which can cause all damage.
Ankle fractures account for 9% of all fractures. In the United States, ankle fractures are the most common lower limb fractures and are the most frequent fracture or injury in the emergency room. The bimalleolar fracture accounts for 60% of all ankle fractures, with an incidence of 187 fractures per 100,000 people. This fracture has a bimodal distribution and most commonly affects older women, young males. Ankle fracture is the third most common fracture overall, and in the athletes, it is the most frequently encountered fracture. Also, this is the third most frequent fracture in patients over 60 years of age.
The patient history should investigate multiple aspects of the injury, including pain location and the mechanism of injury. The patient must describe the injury's event and the force directed toward the ankle along with the intensity of this force. Higher levels of force should raise the suspicion of more complications. The foot and ankle position during injury also requires analysis because it will help to classify the fracture according to the Lauge-Hansen classification system. Past medical history, such as diabetes, peripheral vascular disease, and metabolic bone disease, may affect treatment plans. Chronic medications as corticosteroids can cause osteoporosis. So, it is necessary to ask about medication history.
On physical examination, it is essential to examine the normal ankle before the injured one to detect any differences between the two ankles and set a baseline to elucidate any deviation from the normal. It is also important to examine the knee, fibula, tibia, ankle, and foot and look for any signs of fracture like swelling, redness, hematoma formation, and lateral or medial tenderness malleolus or the proximal head of the fibula. The inability to bear weight on the injured foot is indicative of a fracture, and palpation can identify the fracture's exact location.
The clinician must ensure that the foot and ankle's neurovascular state is intact, including examining the sural artery, saphenous vein, and superficial peroneal nerve, and by assessing the motor function, sensation, capillary refill time, and pulses in the site of the injury. Examine both the active and passive range of motion of the joint, as well as weight-bearing status. Also, assess if there are any signs of open wounds or compartment syndrome.
According to the Ottawa Ankle Rules, the clinician should not order ankle radiographs unless there is pain or tenderness in the ankle malleoli along with one of the following:
Ankle X-ray is the best initial investigation, requiring three views:
Sometimes the tenderness is present in the proximal leg in addition to the widening of the syndesmosis, without obvious fracture in the ankle; however, there is a fracture in the proximal fibula. It provides a clue to the rupture of the syndesmosis. This presentation calls for an image for the tibia and fibula to diagnose this injury called Maisonneuve fracture, which is a spiral fracture in the proximal third of the fibula.
Usually, weight-bearing films, if possible, are the best option to diagnose syndesmotic injuries.
In treatment, assessment of the patient and the injury should proceed in a systematic approach according to ATLS guidelines. The primary survey should come first, ruling out any life-threatening injuries. Then, the examiner can manage the ankle fracture, first checking if there is any neurovascular damage that needs an urgent ankle reduction to regain the foot's vascularity and to avoid long-term sequence. A skin integrity examination is essential because open fractures could be treated primarily by external fixators. Open fractures can lead to delayed union, infection, and skin necrosis.
Most bimalleolar fractures are unstable fractures and require treatment with open reduction internal fixation (ORIF). The management plan can be for either operative or non-operative treatment.
Uses a below-knee cast for six weeks or a total contact cast for three months in patients with diabetes; indicated if the fracture is stable or when the patient cannot tolerate surgical fixation. It needs repeat ankle X-rays in a week to check for any displacement. Also, patients should be on thromboprophylaxis.
ORIF is indicated when the fracture is unstable, such as in a talar shift. The technique is by fibula fixation using plates and screws (lateral malleolus) and medial malleolus fixation using cannulated screws or tension band wiring or plate over medial malleolus in certain types of medial malleolus fractures (Lauge-Hansen supination-adduction fracture pattern). Also, if there is syndesmotic injury is, syndesmotic screws should be inserted (there are some intraoperative tests to check syndesmosis integrity, one of them called the Cotton test). If the posterior malleolus fracture is more than 25%, a CT scan is necessary, and it requires posterior fixation using cannulated screws or, in some situations, plating.
Previously, surgeons stated that a reduction of the lateral malleolus was the critical element in treating ankle fractures. Today it is accepted that the deep deltoid ligament is the primary ankle stabilizer preventing lateral talar shift and external rotation of the talus.
The bimalleolar fracture can have a poor prognosis, depending on the patient and operation, like the elderly, persons with diabetes, and especially those with comorbidities. In general, full weight-bearing takes time and is usually only possible at 12 to 16 weeks, but it generally takes up to 6 months to achieve full weight-bearing with final functional recovery. With operative intervention, the mortality at one year after the surgery is 12% in patients older than 65 years, increasing to 50% for patients over 95 years old.
The complication includes: wound infection, wound hematoma, delay of wound healing, dislocation, arthrosis, inadequate reduction, complex regional pain syndrome, compartment syndrome, impingement syndrome, limited range of motion, malunion, malunion, and Charcot arthropathy mainly in diabetic patients. The long-term complications include deformity, infection, ulceration, ankle osteoarthritis, and amputation. Until the patient reaches full weight-bearing, they must take thromboprophylaxis to prevent the development of DVT or pulmonary embolism.
In patients with bimalleolar ankle fractures, since many patients are under surgical management, it is essential to educate them about the importance of postoperative physiotherapy that results in significant differences in treatment and weight-bearing status. Any delay in the union or any struggle to achieve weight-bearing status rates as a red flag, and the patient must be aware of this point. Patients must closely adhere to postoperative instructions and therapy to achieve optimal outcomes.
Bimalleolar ankle fracture is considered an unstable fracture, and the orthopedic team should be responsible for its management. This fracture needs communication with the orthopedic surgeon to enhance and to improve patient outcomes. The physiotherapist's essential role is to help the patient physical health, muscle strength, and weight-bearing abilities after the surgery. The emergency team should perform emergency fracture reduction. After the surgery, all interprofessional team members should follow up with the patient to ensure a full recovery. This team includes:
At home, the patient must be given thromboprophylaxis prescriptions and equipment like (walker boots, crutches, canes, etc.), and ensure that there is someone at home to help the patient till full recovery.
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