Limb Alignment Images

Mechanical axis of Lower extremity

• line drawn from center of femoral head to center of ankle joint,
• should pass through center of knee. 

°

Mechanical Axis Measurements

• LDFA = lateral distal-femoral angle
  -angle between mechanical axis of femur and the articular surface of the distal femure
  -Normal 87°
• MPTA = medial proximal tibial angle
  -angle between tibial mechanical axis and the articular surface of the proximal tibia
  -Normal = 87°
• LDTA = lateral distal tibial angle
  -angle between tibial mechanical axis and the distal tibial articular surface
  -Normal =90°

1. Femoral mechanical axis
2. Tibial mechanical axis

• Proximal femoral angle = 84°
• Lateral distal femoral anatomic angle = 81°
• Medial proximal tibial anatomic angle = 87°
• Distal tibial anatomic angle = 90°

(Price CT, Orthopaedics 2005;28:20)