The tibia: location, structure and function

The legs are one of the most weight-bearing areas of the body. To perform that function, the leg has a very strong structure of muscles, bones and joints. In this article, we learn about the tibia – one of the two bones of the lower leg.

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• 1. Location 
• 2. Structure of the tibia
• 3. Function of tibia
• 4. Fracture of tibia

1. Location 

• The tibia is located in the medial front of the lower leg and is a large bone. It has a very important role in the functioning of the entire lower extremities. This bone is responsible for regulating activities in the knee and ankle joints. At the same time, it also bears the main compressive force of the body, allowing flexible movement.
• The tibia at the top fuses with the femur, below with the tarsal bones.
• The tibia of the Vietnamese is about 33.6 cm long, very flat. In addition, due to the habit of squatting or crossing the legs, it is bent more backward at the upper end.
• If the bone is placed upright:
  • Small head downwards.
  • The tip of the small head is inward.
  • Edges sharp, clear front.

Leg bones

2. Structure of the tibia

Close

The tibia is slightly curved in the shape of an S, the upper half is slightly curved outward and the lower half is slightly curved inward. The body of the bone is triangular prismatic in shape, getting bigger and smaller at the bottom. By the lower third of the leg, it turns into a round prismatic shape. So this is the weak point that is prone to fracture.

Sides

• The inner surface is flat, lying just below the skin.
• The outside is concave. When reaching the lower end, the outer face loops forward to become the front face.
• The back has a slipper muscle line.

The shores

• The anterior margin is located just below the skin. Therefore, it is very susceptible to injury if hit hard.
• The interosseous margin is thin, opposite the fibula.
• The inner margin is usually not very clear.

Description of structure and relation

• The proximal head is a large bony mass formed by the medial and lateral condyle. The superior surface of each condyle concave into the superior articular surface abut a femoral condyle. On the dorsal-subcondylar medial condyle, the fibular facet articulates with the tip of the fibula. The superior articular surfaces of the two condyle are separated by the intercondylar region. This region includes the intercondylar convex located between the anterior and posterior intercondylar areas.
• The bony stem has tibial tubercles located anteriorly, below, and between the two condyles. The upper part of the back of the body has a ridge running downward and into the muscle line of the sole.
• The distal end is smaller than the proximal end, with the inferior articular surface facing the talus and the fibula defect pointing outwards to the inferior tip of the fibula. The lower head extends down into a process in the talus to form the medial ankle.

Close-up of tibia

The tibia and fibula are linked together as follows:

The upper ends of the two bones are connected by the superior tibial-fibula joint. This is a synovial joint of the flat type. In which, the medial fibular articular surface fuses with the fibula articular surface of the lateral tibial condyle. This joint is supported by the posterior and anterior fibula ligaments.

The interosseous border of the two bony bodies is connected by the interosseous membrane of the lower leg. The lower ends of the two bones are connected by the tibial-fibula joint. Fibrous tissue connects the medial surface of the lateral ankle (lower end of the fibula) to the fibula defect of the inferior tibia.

Joints with the femur

The tibia is the part of the head bone above the tibia. This bony side joins the condyle of the femur to form the knee joint. This joint area is very flexible, helping to move the knee joint smoothly in normal daily activities such as bending the knee when sitting, stretching the knee when walking. The tibial plateau has a spongy structure with a cartilaginous surface. The specific location of the tibial plateau is the fusion of the medial and lateral condyle depending on the medial and lateral tibial plateau. The structure between the tibial plateau includes the tibial plateau spines. This spike acts as an attachment point for the different types of ligaments here (Anterior cruciate ligament and Posterior cruciate ligament).

Structure of the knee joint

Ankle joint

• The inner part of the head below the lower bone forms the medial ankle, which is located just below the skin. The medial ankle lateral surface has an ankle joint that is in contact with the medial ankle surface of the talus pulley. The facet of the ankle joint is perpendicular to the mandibular aspect at the tip of the tibia. The lower facet joint abuts the upper facet of the talus pulley.
• The outer surface of the lower head is triangular in shape with a defect. This is where the tibia makes contact with the lower end of the fibula.

Blood vessel

The blood vessels that nourish the tibia include three sources:

• Bone feeding arteries. Enter the bony feeding hole posterior to the junction of the medial 13th and the superior 1/3 of the tibia.
• The cephalic and periosteal arteries originate from the muscular arteries.

The blood vessels supplying the tibia are very poor and the further down there is, the less connection there is. Therefore, fractures of the tibia are difficult to heal, especially the lower leg.

3. Function of tibia

• Bear the force directly from the entire body weight. Its special construction and joint facets help maintain a straight leg position. Thereby helping to straighten the posture and gait of the body.
• Creates knee and ankle joints to help the body work flexibly.

This part helps us to have a straight gait

4. Fracture of tibia

The tibia is one of the most commonly broken bones in the body. Depending on the extent of the injury, symptoms of a tibia fracture can range from bruising to severe pain in the lower leg.

>> Learn more: Fracture: Recognizing signs and how to handle it properly?

Classification of tibial fractures

To classify and diagnose the type of injury, your doctor will perform a physical exam and recommend some tests to check for a tibia fracture.

Head fracture above tibia

• Fracture or fracture of the head above the tibia is often the result of a fall from a height or a traffic accident. Soft tissues can be severely affected at the time of fracture. It can be important parts such as ligaments, skin, muscles, nerves , blood vessels, etc. Therefore, your doctor will check and evaluate for any signs of soft tissue damage. This greatly affects the treatment plan for the fracture.

Fracture of the lower head of the tibia (pilon fracture)

• A fracture of the lower tibia is a serious injury with the fracture entering the ankle joint. This type of fracture usually occurs after the foot is subjected to a strong impact. For example, a fall from a height or a traffic accident.
• Fractures of the head below the tibia often cause painful swelling with great swelling, marked pain, swelling of the ankle, and deformity of the ankle structure. Some cases of Pilon fractures with bone fragments sprouting through the skin (open fractures) require prompt surgical treatment to reduce the risk of infection.

Reason

The most common causes of tibia fractures are:

• Due to a fall from a great height or to a hard surface. Usually occurs in the elderly, unsteady walkers and athletes.
• Perform twisting movements such as spinning. Usually occurs due to sports such as skating, skiing, fighting.
• Due to strong impact. Caused by motorcycle accidents, cars can lead to the most serious tibial fracture injuries.
• A person's medical condition can also affect a tibia fracture. Examples include type 2 diabetes and pre-existing bone conditions such as osteoarthritis.

Falling can lead to tibia injury

Signs of a tibia fracture

Typical symptoms are:

• Severe pain in the lower leg.
• Numbness or tingling in the legs.
• The injured leg has no bearing capacity.
• Deformed injured area (leg, knee , ankle, shin...).
• Swelling and bruising around the injured area.
• See the bone shoot out of the skin tear (open fracture).
• Movement in and around the knee is limited.
• Limit movements in and around the knee.

If it is broken, the fibula is usually affected as well.

Diagnostic measures

To diagnose a tibia fracture, your doctor will ask about your health and look for typical signs such as:

• Deformations and deformities are easy to see.
• Skin condition (tearing or healing).
• Degree of bone protrusion (if present).
• Assess swelling and bruising.
• Feelings of instability, pain.
• Assess muscle strength.

Perform X-ray tests, CT scans to confirm the diagnosis of fracture. Imaging tests also help to see if the knee and ankle joints are affected by a tibia fracture.

Therapeutic measures

In fact, the recovery time for a tibia fracture depends on the extent of the fracture. This part takes a long time to heal, which may take 4 to 6 months. To treat a tibia fracture, your doctor may consider medical treatments that include:

• Powder bundle.
• Immobilizes and limits leg muscle function but still allows some movement.
• Physical therapy.
• Exercise at home.
• Use crutches.

>> Casting treatments still account for a large portion of fractures. Read more: Casting after fracture: What to know .

In some cases where medical treatment does not work or the injury is too complicated such as open fracture, broken bone or weak leg bone… the doctor may suggest the patient to perform surgery. The following techniques may be used to treat a tibia fracture:

• Secure the broken tibia in place with screws, rods, or steel plates.
• External fixation, connect screws or broken bone pins with an outer metal rod to secure the locating pin.
• Combine physical therapy, functional exercise at home, and additional pain medication.

Use screws to fix the legs

Living with trauma

The recovery phase begins immediately after surgical or non-surgical treatment. During this period, the patient must follow the advice of the orthopedic surgeon. This is especially important because the patient needs to understand the surgeon's instructions regarding load bearing, knee mobility, and the use of external immobilizers (casts or splints). Your doctor will also talk about possible effects on daily living, life, work, family responsibilities, and recreational activities.

The tibia is the major weight-bearing bone in the lower leg. Due to the great pressure and close proximity to the skin, this part is often injured. Understanding the structure and function helps us to be proactive in the prevention and treatment of injuries to the tibia as well as the knee and ankle joints.

Doctor Luong Sy Bac