The medial malleolus is the bump on the inner side of the ankle joint. This is the end of the shin bone (tibia), and forms the support for the inner side of the ankle joint. The medial malleolus is also the attachment of the major ligament on the inner side of the ankle, called the deltoid ligament.
Fractures of the medial malleolus are relatively uncommon, and usually occur as part of a more complex pattern of ankle fractures, including bimalleolar and trimalleolar fractures. That said, isolated fractures of the medial malleolus do occur, though they are relatively uncommon.
Medial Malleolus Fractures
An isolated fracture of the medial malleolus generally occurs when the foot is forcefully rolled inwards or outwards. When the foot rolls inwards, this causes a compression of the medial malleolus on the inner side of the ankle. When the foot rolls out, this pulls tension on the medial malleolus, which can also cause a fracture.
Medial malleolus fractures can also occur as a stress fracture. In these cases, there is no forceful injury, but rather the repetitive stress of an activity causes the bone to weaken. Stress fractures of the ankle are most often seen in endurance athletes or military recruits.
Signs of a Medial Malleolus Fracture
Fractures of the medial malleolus cause symptoms including:
- Pain on the inner side of the ankle
- Swelling and bruising of the foot and ankle
- Difficulty walking
If these symptoms occur, you should be seen by a physician to determine if you have a fracture of the bone. There are well established criteria to determine if an x-ray is necessary. If an x-ray is done, the fracture should be easily detected; there is seldom a need for any other tests to be done.
As stated, whenever a medial malleolus fracture is seen, there are concerns about other damage to the bone and ligaments that may cause a more complex ankle injury. Any patient with a medial malleolus fracture should be carefully examined to ensure there is no other fracture or ligament damage surrounding the joint.
Treatment of a Medial Malleolus Fracture
There are options to treat medial malleolus fractures both non-surgically and surgically. In general, most doctors recommend surgery for fractures that are displaced (not well aligned) or those that occur in very active patients.
There have been several studies that have documented good healing of medial malleolus fractures treated without surgery. Most often these fractures are not out of position, and these patients are relatively lower demand (more sedentary). Non-surgical treatment is also often preferred if the fragment of bone is too small to be effectively repaired.
For fractures that are not well positioned, or in very active patients, a surgical procedure to line up and stabilize the bone is often recommended. The bone is usually held in position with metal screws, although there are several other options that can be considered if screws are not going to work for the particular fracture pattern.
Complications of Treatment
If surgery is performed, the greatest concerns are infection and healing problems. The ankle joint is especially prone to these problems after surgery because there is little to protect the bone, with just a layer of skin covering the surgical repair. Infection of the surgical site is a significant concern. Because of this, most doctors either perform surgery immediately (before any swelling of the soft-tissues has developed), or wait days or even weeks to allow the swelling to subside.
The other major concern with any ankle fracture injury is that while the bone tends to heal very well, there is often cartilage damage inside the ankle joint. This cartilage damage can lead to early ankle arthritis. Depending on the type of fracture, your surgeon may be able to visually inspect the cartilage, and some surgeons may opt to perform an ankle arthroscopy at the time of repair to better see the cartilage. It is very important that the bone be lined up perfectly to minimize the chance of developing arthritis later in life.
Michelson JD "Ankle Fractures Resulting From Rotational Injuries" J Am Acad Orthop Surg November/December 2003; 11:403-412.