Medical knowledge page data
Required time hours
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Part of Deformity Correction Of Lower Limb Bones
Type Medical knowledge page
Keywords Orthopedic Surgery, Complex Bone Deformity, Lower-limb, Surgical Training, Surgical Simulation, X-ray planning, 3D Printing, Cloud software
SDG Sustainable Development Goals SDG03 Good health and well-being
Authors Amit Dinanath Maurya
Published 2021
License CC-BY-SA-4.0
Affiliations AlgoSurg Inc
Mangal Anand Hospital (Mumbai)
Global Surgical Training Challenge
Impact Number of views to this page. Views by admins and bots are not counted. Multiple views during the same session are counted as one. 119

Video Summary[edit | edit source]

  • 0:14 Mechanical Axis of the leg
  • 1:15 Varus and Valgus
  • 1:40 Mechanical Axis Deviation (MAD)

Mechanical Axis Deviation (MAD)[edit | edit source]

The mechanical axis of the lower limb or the leg is different from the mechanical axis of femur and tibia bones. It is defined as a line drawn from femoral head center to the ankle center.

Fig. 6a. Mechanical Axis Deviation (MAD).
The distance between the leg mechanical axis line and the center of the knee in the frontal plane is called the Mechanical Axis Deviation (MAD). The normal range of MAD is 8+/-7 mm medially

Hip-Knee-Ankle angle (HKA)[edit | edit source]

Fig. 6b. Hip-Knee-Angle (HKA)

The MAD is described as either medial or lateral. Medial and lateral MADs are also referred to as varus or valgus malalignments, respectively (Fig. 6b)

The HKA angle is the medial angle between the mechanical axis line of femur and mechanical axis line of tibia in the frontal plane.

The normal range of HKA is 180 +/- 3°. If HKA < 177°, leg is known as to be in varus malalignment and if HKA > 183°, leg is in valgus malalignment (Fig. 6b)