1. Anatomy and Physiology of Tibia and FibulaTIBIA
The inner and thicker of the two lower leg bones. It is the supporting bone of the lower
leg andruns parallel to the narrower lower leg bone, thefibula,to which it is attached
byligaments.The tibia, or shinbone, articulates with thecondylesof thefemur , or upper leg
bone, and the head of the fibula above, and with the talus and the distal end of the fibula
below. It has an expandedupper end, a smaller lower end, and a shaft.At the upper end are
the lateral and medial condyles (sometimes called medial and lateral tibialplateaus),
which articulate with the lateral and medial condyles of the femur, the lateral andmedial
semilunar cartilages intervening. Separating the upper articular surfaces of the
tibialcondyles are anterior and posterior intercondylar areas; lying between these areas is
theintercondylar eminence.The lateral condyle possesses on its lateral aspect a circular
articular facet for the head of thefibula. The medial condyle shows a groove on its
posterior aspect for the insertion of thesemimembranosus muscle.The shaft of the tibia is
triangular in cross section, presenting three borders and three surfaces.Its anterior and
medial borders, with the medial surface between them, are subcutaneous. Theanterior
border is prominent and forms the shin. At the junction of the anterior body with the
upper end of the tibia is the tuberosity, which receives the attachment of the ligamentum
patellae. Theanterior border becomes rounded below, where it becomes continuous with
the medial malleolus.The lateral and interosseous border gives attachment to the
interosseous membrane.The posterior surface of the shaft shows an oblique line, the
soleal line. Below the soleal line avertical ridge passes downward, dividing the posterior
surface into medial and lateral areas.The lower end of the tibia is slightly expanded and
on its inferior aspect show a a saddle-shapedarticular surface for the talus. The lower end
of the tibia shows a wide, rough depression on itslateral surface for articulation with the
fibula.
Fracture of the tibia
The tibia is one of the most commonlyfracturedbones. It may break across the shaft as a
resultof a direct blow to the front of the leg, or at the upper end from a blow to the
outside of the legbelow the knee. Fracture of the lower edge of the tibia may accompany
dislocation of the ankleand fracture of the fibula in a Pott's fracture, caused by violent

2. twisting of the ankle. Prolongedrunning or walking on hard ground may cause a stress
fracture of the tibia.Some fractures of the shaft heal satisfactorily if the leg is
immobilized in a plaster cast, usually for about six to eight weeks. If the bone ends are
displaced or unstable, an operation may be neededto fasten them together with a nail or
screw.