What is the Medial Malleolus?

Meg Higa

The medial malleolus is the spherical bony protrusion on the inner side of the leg, just above the ankle joint. A similar protrusion on the outer side, called the lateral malleolus, is attached to the fibula bone of the lower leg. The former bulge is the terminal end of the tibia, or shin bone; both serve as anchor point for the ligaments and tendons that secure the foot to the leg. Although the medial malleolus is in a protected location and not particularly prone to traumatic injury, stress fractures that are sometimes overlooked can occur. Orthopedic doctors strongly recommend treatment of such micro-fractures.

Fractures of the medial malleolus may occur as a result of playing sports.
Fractures of the medial malleolus may occur as a result of playing sports.

In the leg, the medial malleolus begins flush with the tibia and tapers down and outward into a pyramid shape. The outer surface of the bone just beneath the skin is slightly convex; correspondingly, the inner surface in contact with both the tibia and the talus bone of the foot is concave. Attached to the coarsened — and slightly depressed — base of the pyramid is the deltoid ligament, which holds the ankle joint in place. The lateral malleolus is similar in shape and nearly identical in function.

Wearing supportive footwear may help prevent many medial malleolus injuries.
Wearing supportive footwear may help prevent many medial malleolus injuries.

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The two bones of the lower leg are the fibula and tibia. The latter, the larger of the two, connects the femur bone of the upper thigh at the knee with the talus bone of the foot at the ankle. On the lower back side of the fibula is the lateral malleolar sulcus, and on the back side of the tibia is the medial malleolar sulcus — vertical grooves along which a twin set of tendons nestles and extends to connect the foot. These critical tendons are partially covered and protected by the two malleoli.

Fractures may occur as a result of running.
Fractures may occur as a result of running.

Fracture of the medial malleolus is uncommon. The tibia is a necessarily strong bone, but excess stress from compression or torsion, such as landing from a jump or rolling an ankle, can cause trauma. Likewise, the bones of the foot are not immune to trauma. When such leg injuries occur, the likelihood that the medial malleolus also will have sustained a fracture is increased. It will vary in severity and type, the most common being a clean avulsion or a hairline stress fracture.

Fracture of the medial malleolus is uncommon, but may occur in seniors or other people with weakened bones.
Fracture of the medial malleolus is uncommon, but may occur in seniors or other people with weakened bones.

Of course, blunt force can cause the bone to chip. Fractures can sometimes result from running, jumping, sports that involve sudden change of direction or weight being repeatedly exerted on the ankle joint. Often, the pain, bruise and swelling of a micro-fracture dissipates relatively quickly, leaving a dull ache, sometimes also felt in the Achilles tendon. Tenderness might persist, "pins and needles" or numbness might be prominent, or pain might be felt only during certain types of movements by the ankle.

Running for long distances may cause stress fractures.
Running for long distances may cause stress fractures.

Treatment for a medial malleolus fracture is determined by it severity. A displaced fracture might require a prosthetic plate and cortical screws, and an undisplaced break might require only immobilization for several weeks. A stress fracture of the medial malleolus, if ignored, usually will worsen and require reconstructive surgery. If diagnosed and treated early, the prognosis for full recovery from most fractures is exceptionally good.

The tibia, or shin bone, is one of the strongest weight-bearing bones in the body.
The tibia, or shin bone, is one of the strongest weight-bearing bones in the body.
Ignoring a stress fracture of the medial malleolus will eventually require surgery.
Ignoring a stress fracture of the medial malleolus will eventually require surgery.
The inner surface of the medial malleolus in contact with both the tibia and the talus bone of the foot is concave.
The inner surface of the medial malleolus in contact with both the tibia and the talus bone of the foot is concave.

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