A 71-year-old female with a history of rheumatoid arthritis, macular degeneration, and malignant melanoma presents to the ED after tripping over her robe, causing her right ankle to invert, and leading to a ground-level fall.
Written by Kareem Shahin | Sports Medicine Review | Category: Case Report
A trimalleolar fracture is a type of ankle fracture that occurs when you fracture three different areas in your ankle called the malleoli: the medial malleolus, lateral malleolus, and posterior malleolus. This type of fracture is usually sustained after high-impact injuries, including falls, car accidents, or sports injuries. It is universally unstable, commonly presenting with dislocation and radiographically occult lesions to ligaments and cartilage. Most ankle fractures are malleolar fractures with 60-70% occurring as unimalleolar (one-part) fractures, 15-20% as bimalleolar (two-part) fractures, and 7- 12% as trimalleolar fractures (three-part). The incidence of ankle fractures is about 187 fractures per 100,000 people per year and this rate continues to increase in many industrialized countries. Risk factors include cigarette smoking, high body mass index, and the incidence is bimodal; higher in younger men (15-25 years) and in older women (50-70 years).
The ankle joint is a hinged synovial joint that is composed of three bones: the talus, the tibia, and the fibula. The articulation of these three bones creates three smaller joints within the ankle: the talocrural joint (also called talotibial joint, tibiotalar joint, talar mortise, talar joint), the subtalar joint (also called talocalcaneal), and the inferior tibiofibular joint. These bones are held together by three sets of ligaments: the medial/deltoid ligaments that start at the medial malleolus and fan out to connect to the talus, calcaneus, and navicular bones, the lateral ligaments that start at the lateral malleolus and fan out to connect to the talus and calcaneus, and the syndesmotic ligaments that connect the tibia and fibula. These ligaments are responsible for anchoring the bones of the ankle with each other, maintaining structural and biomechanical stability, , preventing excessive twisting and folding.
The initial imaging modality of choice for diagnosis for ankle injuries, including a trimalleolar fracture, is plain radiography. Three views are typically obtained: the AP view is used to evaluate the ankle mortise (the articular surface formed by the horizontal portion of the distal tibia and the dome of the talus), the lateral process of the talus, and swelling about the medial or lateral malleoli. The mortise view is used to evaluate the talus and the margins of the joint space. Typically, all portions of the mortise should be symmetric and less than 4mm in width. The lateral view is used to evaluate for effusions and the posterior tibia. A stress x-ray is a modified x-ray in which pressure is applied on the injured ankle that may uncover instability not seen on regular imaging. CT is not typically required in the initial evaluation, however it can be obtained for suspicion of occult fractures or pre-operative planning.
The ankle exam should begin with inspection: evaluation for bruising, gross deformities, swelling, etc. Following inspection, palpate along the entire tibia and fibula (especially the proximal fibula to assess for a Maisonneuve fracture) until you reach the malleoli. The posterior tips of the lateral/medial malleoli, the base of the fifth metatarsal, and the navicular (Ottowa Ankle Rules) should also be palpated. The ankle range of motion primarily occurs in the sagittal plane with 10-20° of dorsiflexion and 40-55° of plantar flexion. The ankle can also invert up to 30° and evert up to 20°. Once the range of motion is assessed, evaluate strength in plantar flexion and dorsiflexion. Lastly, perform special tests of the ankle if the patient tolerates the maneuvers (unlikely in the case of a trimalleolar fracture).
In a trimalleolar fracture, the ankle will appear swollen and possibly bruised if there is a hematoma, which will limit both the range of motion and strength of the ankle, however, it is important to confirm that plantar and dorsiflexion are intact to assess the peroneal and posterior tibial nerves. Similarly, most patients will not tolerate maneuvers of the ankle for special testing. Sensation and pulses (dorsalis pedis and pretibial pulses) should also be assessed to ensure vascular integrity.
Trimalleolar fractures are universally surgical unless the patient has a contraindication to surgery. Dislocated trimalleolar ankle fractures should be reduced immediately to reestablish joint congruity and reduce concomitant soft tissue injury. If the closed reduction is unsatisfactory, an immediate open reduction should be performed in the operating room. Other emergency indications for immediate intervention include severe soft tissue injury, compartment syndrome, and open fracture with or without concomitant vascular/nerve injury. If non-emergent, surgery may be delayed to ensure reduced soft tissue swelling. A retrospective cohort study in Norway showed no difference in postoperative length of stay, complications, and functional outcomes in those with closed ankle fractures treated with ORIF during the first 8 hours, 8 hours to 6 days, and greater than 6 days. Following surgery, active mobilization with physical therapy is essential and has shown an earlier return to work. Exercises should focus on stability, dorsiflexion, and plantar flexion range of motion and strength.
Upon evaluation, this patient’s physical showed ecchymoses along the medial and lateral malleoli. Sensation was intact to light touch in the tibial, sural, saphenous, deep, and superficial peroneal nerve distributions. Her foot and toes were warm and well perfused with a brisk cap refill and 3+ dorsalis pedis pulse. She underwent an open reduction internal fixation of the right trimalleolar fracture dislocation with arthroscopically assisted right distal tibiofibular syndesmosis. She was healing well at 3 weeks of follow up.