Table of ContentsView AllTable of ContentsAnatomy of the AnkleCausesSymptoms of an Ankle FractureBimalleolar FracturesTrimalleolar FracturesTreatment
Table of ContentsView All
View All
Table of Contents
Anatomy of the Ankle
Causes
Symptoms of an Ankle Fracture
Bimalleolar Fractures
Trimalleolar Fractures
Treatment
Bimalleolarandtrimalleolarankle fracturesare specific types of injuries that commonly occur because of trauma, such as slips on the ice, a fall down stairs, sports injuries, and car crashes.
With a bimalleolar fracture, bones on both the inner and outer side of the ankle are injured. The same is true of a trimalleolar ankle fracture, but with a third injury to the back of thetibiabone at the ankle joint.
This article explains the anatomy, structure, and function of the bones involved in bimalleolar and trimalleolar ankle fractures. It discusses how these fractures occur, and why these more complex ankle fractures typically require surgery.
The ankle joint is where the bones ofthe leg(the tibia andfibula) meet with the bones on the hindfoot (talus) to form a joint that allows the foot to bend up and down. The ankle joint is susceptible to injury and one common type of injury is called anankle fracture.
Other bones around the ankle joint can be injured as well, but an ankle fracture usually involves the bones of the tibia and fibula.The ends of these bones, with the bony bumps you see on the inner and outer side of the ankle, are called themedial malleolus(tibia) and lateral malleolus (fibula).
Bimalleolar and trimalleolar ankle fractures are considered more serious, or complex, fractures because they involve the ends of both the tibia and fibula bones. This leads to increased instability that, in most cases, will need surgical repair.
What Is a Bimalleolar Fracture?A bimalleolar fracture is an ankle fracture that involves both the tibia and fibula, the lower leg bones that end on either side of the ankle. They form the small bumps on the inner side and the outer side of your ankle.
What Is a Bimalleolar Fracture?
A bimalleolar fracture is an ankle fracture that involves both the tibia and fibula, the lower leg bones that end on either side of the ankle. They form the small bumps on the inner side and the outer side of your ankle.
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Causes of Ankle Fractures
Most bimalleolar and trimalleolar ankle fractures are serious injuries. They often occur from high energy injuries such as falls and motor vehicle collisions.
In addition to the force of impact, there is often a significant force of rotation on the ankle seen in sports injuries and serious falls.
Sometimes these fractures can occur due to a weakening of the bone, most commonly in people with osteoporosis. In people with underlying conditions that weaken the bone, these bimalleolar and trimalleolar ankle fractures can occur with less force than in other people.
Common symptoms of an ankle fracture include pain and swelling.These symptoms may be just in the ankle itself, or they may be felt in other parts of the foot and up toward the knee.
Putting pressure on the injury can make pain worse if you have a trimalleolar or bimalleolar fracture.
Bimalleolar Ankle Fractures
When a bimalleolar ankle fracture occurs, there is an injury to both the medial malleolus (inner side of the ankle) and the lateral malleolus (outer side of the ankle). Because both sides are injured, the ankle joint becomes unstable.
This means that the fracture disrupts the structural integrity of the ankle (joint). Because the joint is unstable, it is susceptible to damage and early ankle arthritis if left untreated. Therefore, the typical treatment is to surgically repair the fracture to stabilize the ankle joint.
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Bimalleolar Equivalent Ankle Fractures
One special subset of these fractures is called a bimalleolar equivalent fracture. This typically occurs when there is a fracture of the lateral malleolus and a ligament injury on the inner side of the ankle (the deltoidligament).
While this particular injury does not involve a bone injury on the inner side of the ankle, the ligament injury that has occurred causes the ankle joint to become unstable and requires surgical treatment to stabilize the joint.
Bimalleolar equivalent fractures need to be considered any time a lateral malleolus fracture has occurred. If there is pain or swelling on the inner side of the ankle, a bimalleolar ankle fracture may be present.
Special x-rays, called stress x-rays, can be performed to look for signs of instability of the ankle joint.
Trimalleolar Ankle Fractures
Trimalleolar ankle fractures are another variant of this type of injury. The typical bimalleolar fracture involvesbone injuryto the inner and outer side of the ankle. People who sustain a trimalleolar ankle fracture also have a bone injury at the back of the tibia (posterior malleolus fracture) near the ankle joint.
Often, this does not change the treatment from that of a bimalleolar ankle fracture. However, if bone injury in the back of the tibia, called the posterior malleolus, causesinstability of the ankle joint, it may need to also be repaired at the time of surgery.
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Treatment of Complex Ankle Fractures
Treatment of all of these injuries is similar, and almost always requires surgery. The surgical procedure is performed to repair the bones, most often with metal plates and screws.These implants repair the bones to restore the stability of the ankle joint. It is very important to repair the bones with proper alignment. If not lined up perfectly there is a higher chance of developing early ankle arthritis.
As mentioned, infection and wound complications are the most worrisome concerns associated with ankle fracture surgery. Other common complications include stiffness and long-term swelling. Many patients notice swelling after ankle fracture surgery for six months, and may always have some increased swelling. Another concern is that because the bone is directly under the skin, metal plates and screws aresometimes bothersome and require removal. Lastly, even with appropriate care, surgical repair, and proper rehabilitation, ankle arthritis can occur.
A Word From Verywell
5 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Orthopaedic Surgeons.Ankle fractures (broken ankle). March 2013Hospital for Special Surgery.Ankle Fractures (Broken Ankle): Anatomy, Symptoms, Treatment.Clements JR, Motley TA, Garrett A, Carpenter BB.Nonoperative treatment of bimalleolar equivalent ankle fractures: a retrospective review of 51 patients.J Foot Ankle Surg. 2008;47(1):40-5. doi:10.1053/j.jfas.2007.10.005Xing W, Wang Y, Sun L, et al.Ankle joint dislocation treating dislocated trimalleolar fractures accompanied with the complex posterior malleolus fracture without separation of the tibiofibular syndesmosis.Medicine(Baltimore). 2018;97(37):e12079. doi:10.1097/MD.0000000000012079Lampridis V, Gougoulias N, Sakellariou A.Stability in ankle fractures: Diagnosis and treatment.EFORT Open Rev. 2018;3(5):294-303. doi:10.1302/2058-5241.3.170057Additional ReadingAnderson RB, Hunt KJ, McCormick JJ. “Management of common sports-related injuries about the foot and ankle” J Am Acad Orthop Surg. 2010 Sep;18(9):546-56.
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Orthopaedic Surgeons.Ankle fractures (broken ankle). March 2013Hospital for Special Surgery.Ankle Fractures (Broken Ankle): Anatomy, Symptoms, Treatment.Clements JR, Motley TA, Garrett A, Carpenter BB.Nonoperative treatment of bimalleolar equivalent ankle fractures: a retrospective review of 51 patients.J Foot Ankle Surg. 2008;47(1):40-5. doi:10.1053/j.jfas.2007.10.005Xing W, Wang Y, Sun L, et al.Ankle joint dislocation treating dislocated trimalleolar fractures accompanied with the complex posterior malleolus fracture without separation of the tibiofibular syndesmosis.Medicine(Baltimore). 2018;97(37):e12079. doi:10.1097/MD.0000000000012079Lampridis V, Gougoulias N, Sakellariou A.Stability in ankle fractures: Diagnosis and treatment.EFORT Open Rev. 2018;3(5):294-303. doi:10.1302/2058-5241.3.170057Additional ReadingAnderson RB, Hunt KJ, McCormick JJ. “Management of common sports-related injuries about the foot and ankle” J Am Acad Orthop Surg. 2010 Sep;18(9):546-56.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American Academy of Orthopaedic Surgeons.Ankle fractures (broken ankle). March 2013Hospital for Special Surgery.Ankle Fractures (Broken Ankle): Anatomy, Symptoms, Treatment.Clements JR, Motley TA, Garrett A, Carpenter BB.Nonoperative treatment of bimalleolar equivalent ankle fractures: a retrospective review of 51 patients.J Foot Ankle Surg. 2008;47(1):40-5. doi:10.1053/j.jfas.2007.10.005Xing W, Wang Y, Sun L, et al.Ankle joint dislocation treating dislocated trimalleolar fractures accompanied with the complex posterior malleolus fracture without separation of the tibiofibular syndesmosis.Medicine(Baltimore). 2018;97(37):e12079. doi:10.1097/MD.0000000000012079Lampridis V, Gougoulias N, Sakellariou A.Stability in ankle fractures: Diagnosis and treatment.EFORT Open Rev. 2018;3(5):294-303. doi:10.1302/2058-5241.3.170057
American Academy of Orthopaedic Surgeons.Ankle fractures (broken ankle). March 2013
Hospital for Special Surgery.Ankle Fractures (Broken Ankle): Anatomy, Symptoms, Treatment.
Clements JR, Motley TA, Garrett A, Carpenter BB.Nonoperative treatment of bimalleolar equivalent ankle fractures: a retrospective review of 51 patients.J Foot Ankle Surg. 2008;47(1):40-5. doi:10.1053/j.jfas.2007.10.005
Xing W, Wang Y, Sun L, et al.Ankle joint dislocation treating dislocated trimalleolar fractures accompanied with the complex posterior malleolus fracture without separation of the tibiofibular syndesmosis.Medicine(Baltimore). 2018;97(37):e12079. doi:10.1097/MD.0000000000012079
Lampridis V, Gougoulias N, Sakellariou A.Stability in ankle fractures: Diagnosis and treatment.EFORT Open Rev. 2018;3(5):294-303. doi:10.1302/2058-5241.3.170057
Anderson RB, Hunt KJ, McCormick JJ. “Management of common sports-related injuries about the foot and ankle” J Am Acad Orthop Surg. 2010 Sep;18(9):546-56.
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