Tibia

one of the long tubular bones of the lower leg, which articulates with the femur and head of the fibula at its proximal end and with the talus at its distal end. Also, se tibia.

2. Pathology

The tibia may be involved in innumerable musculoskeletal disorders (Fig.1) (Fig.2).

Agenesis or aplasia of the tibia may occur alone or in combination with distal focal femoral deficiency or fibular hypoplasia and hemimelia. Associated abnormalities may include flexion contracture of the knee, inversion and adduction of the foot, and other anomalies.

Congenital or infantile pseudarthrosis occurs most commonly in the tibia. Radiographic features include anterior bowing of the lower half of the tibia, which may or may not be associated with abnormality of the adjacent fibula. Sclerosis, narrowing of the medullary canal and cystic abnormality may indicate impending fracture of the tibia and pseudarthrosis. The relationships, if any, among congenital pseudarthrosis, neurofibromatosis and fibrous dysplasia remain unclear.

Bowing of the tibia also may occur in Melnick Needles syndrome, in Weismann Netter Stuhl syndrome and in association with fibular aplasia or hypoplasia.

Single or multiple radiolucent Brodies abscesses can be evident during subacute or chronic stages of osteomyelitis, usually of staphylococcal origin. These abscesses appear as circumscribed lesions showing predilection for (but not confinement to) the ends of tubular bones, especially in the metaphysis of the tibia in children.

In Pagets disease, involvement of the tibia is characterized by epiphyseal or sometimes diaphyseal changes, an advancing wedge of radiolucency on radiographs, periosteal apposition of new bone, deformity and fracture.

Deformities such as tibia vara, torsion and sabre shin deformity also involve the tibia. In tibial torsion, the distal end of the bone is rotated toward either the medial malleolus or the lateral malleolus. Sabre shin deformity is an abnormality of the tibia characterized by marked anterior bowing of the lower leg. This defect may be seen in some children with congenital syphilis and in patients with yaws, osteitis deformans and Pagets disease. A similar deformity may occur as manifestation of rickets caused by bowing and a strong posterior pull of the Achilles tendon on the weakened growth plate of the calcaneus.

Fracture of the tibia is common and may occur at various portions of the bone. Stress fracture of the proximal diaphysis of the tibia can occur during running, and stress fracture of the middle and distal tibial diaphysis can take place during long-distance running, marching and ballet dancing. Stress fractures involving the medial malleolus may also be encountered in young athletes. The proximal metaphysis or diaphysis of the tibia is a typical location for a mortise.

In patients with pain in the knee from osteoarthritis, a surgical procedure termed high tibial osteotomy may be performed in more active patients. The Coventry operation involves resection of a wedge of bone from the tibial metaphysis between the joint and the tibial tubercle. The barrel vault osteotomy is a curved osteotomy performed proximal to the tibial tubercle, with rotation of the fragment to the desired position.

DR

DR/RB