The tibia is the main bone of the lower leg, more commonly known as the shin. It is the second largest bone in the body and provides important weight-bearing support. This article looks at the anatomy, articulation, and clinical correlations of the tibia.
The proximal end of the tibia is widened by two condyles, the medial and lateral condyles. These condyles form a flat surface known as the tibial plateau, which articulates with the femoral condyles to form the knee joint. Between the condyles is a region called the intercondylar eminence. This projects upwards on either side as the medial and lateral intercondylar tubercles. The intercondylar tubercles articulate with the intercondylar fossa of the femur. This area is the main site of attachment for the knee's ligaments and menisci.
The shaft of the tibia is prism-shaped and has three borders and three surfaces, the anterior, posterior, and lateral.The anterior border is marked by the tibial tuberosity and is palpable subcutaneously down the anterior surface of the leg as the shin. On the posterior surface is a ridge of bone known as the soleal line, the site of origin for part of the soleus muscle. The soleal line extends inferomedially, eventually blending with the medial border of the tibia. Near the soleal line is usually a nutrient artery. On the lateral border is the interosseous border, which gives attachment to the interosseous membrane that binds the tibia and the fibula together.
Intraosseous access is a form of vascular access used in emergency situations. It allows for the administration of fluids, blood products, and medications directly into the bone marrow. IO access is typically used when intravenous access is not available. There are two main sites in the tibia suitable for IO access, anteromedial surface, 2-3cm below the tibial tuberosity, and proximal to the medial malleolus. Potential complications of IO access include osteomyelitis, iatrogenic fracture, and compartment syndrome. Once IV access is achieved, IO infusions should be discontinued.
At the distal end of the tibia, the bone widens to provide weight-bearing support. The medial malleolus is a bony projection continuing inferiorly on the medial aspect of the tibia. It articulates with the tarsal bones to form part of the ankle joint. On the posterior surface of the tibia is a groove through which the tendon of tibialis posterior passes. The lateral aspect has the fibular notch, where the fibula is bound to the tibia to form the distal tibiofibular joint.
Fractures of the tibia are relatively common, and can be split into two main types. High energy trauma is more common in the younger population, while low energy trauma or insufficiency fractures are more common for the elderly. Fractures of the tibia most commonly occur at its shaft, often accompanied by fibula fractures. Fractures of the proximal tibia, also known as tibial plateau fractures, may break the condyles and may also damage the menisci and ligaments of the knee. These fractures are classified using the Schatzker classification and may require surgical management if very displaced.
The tibia is a long bone of the leg located between the knee and the ankle joints. It is cylindrical in shape, with a shaft and two distal ends that articulate with other bones. The shaft of the tibia is prism-shaped, with three borders and three surfaces. The anterior border, for instance, is palpable subcutaneously down the anterior surface of the leg as the shin. The posterior surface is marked by a ridge of bone known as the soleal line. The lateral border is referred to as the interosseous border. Meanwhile, the distal end of the tibia widens to assist with weight-bearing. The medial malleolus is a bony projection continuing inferiorly on the medial aspect of the tibia, which articulates with the tarsal bones to form part of the ankle joint.
Located between the condyles is a region called the intercondylar eminence. This area projects upwards on either side as the medial and lateral intercondylar tubercles, and is the main site of attachment for the ligaments and the menisci of the knee joint. The intercondylar tubercles of the tibia articulate with the intercondylar fossa of the femur.
Intraosseous access is a form of vascular access used in the emergency setting, allowing the administration of fluids, blood products and medications directly into the bone marrow. It is typically used in an emergency when intravenous access is not obtainable. There are two main sites in the tibia that are suitable for IO access:
Complications of IO access include osteomyelitis, iatrogenic fracture and compartment syndrome. It is important to discontinue IO infusions when IV access has been achieved.
Fractures of the tibia are relatively common. The two main types are high energy trauma, which is more common in the younger population, and low energy trauma or insufficiency fractures, which is more common in the elderly. The most common type of fracture is at the shaft of the tibia, which is typically associated with fibula fractures. Proximal tibia fractures, known as tibial plateau fractures, can involve injury to the menisci and ligaments of the knee; these fractures are classified using the Schatzker classification and may require operative management. Complications of tibial fractures include compartment syndrome, which should be monitored for in the pre and post-operative phases. At the ankle, the medial malleolus can be fractured.
Medial malleolus fractures are caused by the ankle being twisted inwards (over-inversion), where the talus of the foot is forced against the medial malleolus, producing a spiral fracture. These types of fractures rarely happen in isolation and the lateral malleolus is usually fractured as well; these types of fractures may require operative management to be stabilized.
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