Leg Deformity Correction: How to perform

Last updated on July 6 2022

Description

Leg deformity is an abnormal size, shape, position or composition of a limb, which may be congenital and inherited or an acquired defect. This procedure can be used to correct limb alignment. To perform a limb alignment, it is necessary to have knowledge of certain anatomical measurements and provide the anatomical and mechanical axes of deformed limbs, which are compared to standard values, to later simulate corrective procedures.

This procedure is intended to provide information that enables the healthcare professional to select a plane that describes the point where the bone should be cut and the angle which has to rotate around a marked center of rotation, in order to restore the length and the correct axis for load transfer. 

Measurements

The measurements made by the procedure are displayed in the image:

• Mechanical Lateral Proximal Femoral Angle (mLPFA): the angle between the line starting in the center of the femoral head and ending in the greater trochanter, and the femoral mechanical axis, measured on the lateral side;
• Mechanical Lateral Distal Femoral Angle (mLDFA): the angle between the femoral distal articular surface and the femoral mechanical axis, measured on the lateral side;
• Mechanical Tibiofemoral Angle (mTFA): the angle between the line from the center of the femoral head to the center of the femoral articular surface and the line from the center of the tibial plateau to the center of the tibial distal articular surface;
• Joint Line Congruence Angle (JLCA): the angle between the lines of the femur and tibia plateau;
• Mechanical Medial Proximal Tibial Angle (mMPTA): the angle between the tibial plateau and the tibial mechanical axis, measured on the medial side;
• Mechanical Lateral Distal Tibial Angle (mLDTA): the angle between the tangent line of the tibial distal articular surface and the tibial mechanical axis, measured on the lateral side;
• Mechanical Axis Deviation (MAD): perpendicular distance from the center of the knee to the mechanical axis, i.e. the length between the midpoint of the tibial surface and the mechanical axis;
• Mechanical Axis of the Femur (MAF): is the femur length, i. e., the length between the center of the femoral head and the midpoint of the femur plateau;
• Mechanical Axis of the Tibia (MAT): is the tibial length, i. e., the length between the tangent line of the tibial distal articular surface and the midpoint of the tibial plateau;
• Mechanical Axis (MA): is the total leg length, i. e., the length between the center of the femoral head and the tangent line of the tibial distal articular surface;
  
• Anatomical Femoral Axis to Mechanical Tibial Axis Angle (aFA - mTA): the angle between the anatomical axis of the femur and the mechanical axis of the tibia;
• Anatomical Medial Proximal Femoral Angle (aMPFA): the medial angle formed between the anatomical axis of the femur and a line connecting the center of the femoral head and the tip of the greater trochanter;
• Anatomical Lateral Distal Femoral Angle (aLDFA): the lateral angle formed between the anatomical axis of the femur and the knee joint line of the femur in the frontal plane.