Tibia
The proximal tibia is expanded to receive the condyles of the femur. The shaft of the bone flares out into lateral or medial buttresses which form the medial and lateral condyles. The tibia is the weight bearing bone of the leg whereas the fibula serves the muscular attachments and for completion of the ankle joint. The superior articular surface of the tibia presents two facets. The larger medial facet is oval in shape and has a slight concavity. The lateral facet is nearly round and although concave from side to side, it is convex in front. The rims of the facets are in contact with the medial and lateral menisci but the central portions receive the condyles of the femur. Both tibial facets have a posterior inclination with respect of the shaft of the tibia of approximately 10°. On inspection of the tibial plateau, it would appear as though the femoral and tibial surfaces do not conform. However, this is more apparent than real. In the intact knee the menisci enlarge the contact area considerably and increase conformity of the joint surfaces.
The medial portion of the tibia between the articular facets is occupied by an intercondylar eminence with two tubercles. The articular surface of the tibia continues onto the adjacent sides of the medial and lateral intercondylar eminences. Anterior to the intercondylar eminence is a depression, the anterior intercondylar fossa to which, from anterior to posterior, the anterior horn of the medial meniscus, the ACL and the anterior horn of the lateral meniscus are attached. Behind this region are two elevations, the medial and lateral tubercles. They are divided by a gutter-like depression, the intertubecular sulcus. On an antero-posterior radiograph the medial tubercle usually projects more superior than the lateral tubercle. On the lateral radiograph the medial tubercle is located anterior to the lateral tubercle. The tubercles do not function as attachment sites for the cruciate ligaments or the menisci but may act as side to side stabilisers by projecting towards the inner sides of the femoral condyles. In the posterior intercondylar fossa, behind the tubercles, the lateral then the medial menisci are attached anterior to posterior. Most posterior, the posterior cruciate ligaments inserts on the margin of the tibia between the condyles. From its origin, the posterior cruciate ligament travels anterior and slightly medial where it is joined by one or two cords from the lateral meniscus (the anterior and posterior menisco-femoral ligaments (or the ligament of Humphrey and the ligament of Riesburg respectively)) to attach the medial condyle of the femur in the intercondylar notch.
On the anterior aspect of the proximal tibia, the tibial tuberosity is the most prominent feature and is the attachment site of the patellar tendon. Approximately 2 to 3 cm lateral to the tibial tubercle is Gurdy's tubercle, which is the insertion site of the ilio-tibial band (ITB). Posterior to Gurdy's tubercle, the lateral condyle has a nearly circular facet on its postero-inferior surface for articulation with the head of the fibula.
At its upper medial portion the tibia provides the attachment for the medial collateral ligament, both the deep and superficial bands of the medial collateral ligament. The medial surface of the body of the tibia is smooth and convex. Its upper one third receives the insertion of the sartorius, gracilis and semitendinosus tendons (medial hamstrings).
Last Updated (Thursday, 10 February 2011 12:48)
