BIOMECHANICS Axes of the lower limb

BIOMECHANICS Axes of the lower limb

The anatomical axes of the femur and tibia are defined by their medullary canal. The mechanical axis of the lower limb runs from the centre of the femoral head, through the inter condylar notch of the knee to the centre of the ankle joint. The angle between the anatomical and mechanical axes of the femur is usually between 5° and 7° (often called the valgus cut angle in arthroplasty) ( Figure 40.2 ). A total knee replacement - components using cuts perpendicular to the mechanical axis. Knees with malalignment are more prone to injury or degener - ation in the loaded compartment. Realignment surgery (tibial or femoral osteotomy) can o ffl oad the damaged compartment to reduce symptoms and slow progression to arthritis.

Femoral anatomical– mechanical angle A natomical Anatomical axis tibia axis femur Mechanical Mechanical axis femur axis tibia Figure 40.2 Axes of the lower limb. Anatomical and mechanical axes are coincident in the tibia but not the femur. (Adapted from Miller M. Review of orthopaedics , 4th edn. Philadelphia: Elsevier, 2004. By kind permission of the publishers.)

BIOMECHANICS Axes of the lower limb

The anatomical axes of the femur and tibia are defined by their medullary canal. The mechanical axis of the lower limb runs from the centre of the femoral head, through the inter condylar notch of the knee to the centre of the ankle joint. The angle between the anatomical and mechanical axes of the femur is usually between 5° and 7° (often called the valgus cut angle in arthroplasty) ( Figure 40.2 ). A total knee replacement - components using cuts perpendicular to the mechanical axis. Knees with malalignment are more prone to injury or degener - ation in the loaded compartment. Realignment surgery (tibial or femoral osteotomy) can o ffl oad the damaged compartment to reduce symptoms and slow progression to arthritis.

Femoral anatomical– mechanical angle A natomical Anatomical axis tibia axis femur Mechanical Mechanical axis femur axis tibia Figure 40.2 Axes of the lower limb. Anatomical and mechanical axes are coincident in the tibia but not the femur. (Adapted from Miller M. Review of orthopaedics , 4th edn. Philadelphia: Elsevier, 2004. By kind permission of the publishers.)

BIOMECHANICS Axes of the lower limb

The anatomical axes of the femur and tibia are defined by their medullary canal. The mechanical axis of the lower limb runs from the centre of the femoral head, through the inter condylar notch of the knee to the centre of the ankle joint. The angle between the anatomical and mechanical axes of the femur is usually between 5° and 7° (often called the valgus cut angle in arthroplasty) ( Figure 40.2 ). A total knee replacement - components using cuts perpendicular to the mechanical axis. Knees with malalignment are more prone to injury or degener - ation in the loaded compartment. Realignment surgery (tibial or femoral osteotomy) can o ffl oad the damaged compartment to reduce symptoms and slow progression to arthritis.

Femoral anatomical– mechanical angle A natomical Anatomical axis tibia axis femur Mechanical Mechanical axis femur axis tibia Figure 40.2 Axes of the lower limb. Anatomical and mechanical axes are coincident in the tibia but not the femur. (Adapted from Miller M. Review of orthopaedics , 4th edn. Philadelphia: Elsevier, 2004. By kind permission of the publishers.)