الظنبوب

The tibia is the larger and stronger of the two leg bones and bears approximately 85-90% of the body's weight transmitted from the femur through the knee joint down to the foot. Its broad proximal end—the tibial plateau—provides a wide, stable articular surface for the femoral condyles. The tibia transmits these forces to the ankle joint and through the talus to the foot.

A tibial plateau fracture involves the proximal articular surface of the tibia within the knee joint, usually caused by high-energy trauma (motor vehicle accidents) or axial loading combined with a valgus or varus force. Because it involves the joint surface, it can disrupt knee stability and articular cartilage, potentially causing long-term post-traumatic osteoarthritis. Treatment depends on fracture displacement and may require surgical fixation to restore joint congruence.

The tibia is the most frequently fractured long bone in the body for several reasons: it lies directly beneath the thin subcutaneous skin along its anteromedial surface with minimal muscle protection, making it vulnerable to direct blows; it bears full weight-bearing loads; and its blood supply is relatively sparse, making healing slower and open (compound) fractures common. The subcutaneous location also makes open fractures and wound complications more likely.

Tibial stress fractures are hairline cracks in the bone caused by repetitive mechanical loading that exceeds the bone's ability to remodel and repair itself. They are common in military recruits undergoing intensive training, long-distance runners, and ballet dancers. They typically present as a gradual onset of anterior shin pain that worsens with activity and improves with rest. Management involves relative rest and gradual return to activity; high-risk cortical fractures on the anterior tibia may require surgery.

Key tibial landmarks include: the tibial tuberosity (anterior prominence below the knee, where the patellar tendon inserts); the medial and lateral tibial condyles (forming the knee joint with the femur); the intercondylar eminence (housing the cruciate ligament attachments); the anterior border (sharp subcutaneous shin); the medial malleolus (inner ankle prominence, forming part of the ankle mortise); and Gerdy's tubercle (lateral condyle, where the iliotibial band inserts).