Normal And Abnormal Functional Anatomy Of The Lower Limb

12.1.07

"Lower limb problems are the most commonly dealt with by physicians."

Physical stress - hip joint
• Trabecular structure of proximal femur generally well-adapted to cope with angle of inclination (normally ~1250 in adult) and bending moments it causes medially.
• However, significant deviations (coxa vara, coxa valga) can lead to reduced mobility and/or fractures of femoral neck.

Iliofemoral ligament prevents hyperextension of hip - strongest ligament in body.

Fracture of neck of femur
• Displacement of distal bone fragment caused by pull of powerful muscles.
• Note in particular: external rotation of leg with foot characteristically pointing laterally.
• Particularly in elderly women, mainly due to thinning of cortical and trabecular bone.
• Avascular necrosis of femoral head is a common complication.

Knee joint
• Articular surface involved in main movement of knee: flexion and extension.
• Articular surfaces of femur represent segment of pulley.
• Cruciate ligaments appear crossed in space.
• Situation important to remember during normal knee movement - also involves some gliding and rotation.
• Cruciate ligaments represented by crossed 4-bar linkage.
• Together with medial and collateral ligaments, intersect at same crossing point - can be maintained in extension and flexion.
• Note: extension in femoral condyles has much greater contact areas as in flexion thus significantly reducing pressure.
• Various structures (e.g. ligaments, menisci and tendons) help stabilise knee joint and dissipate pressure.