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Part of Deformity Correction Of Lower Limb Bones
  • Malalignment: refers to loss of collinearity of the hip, knee & ankle in the frontal plane (MAD exceeds normal range)
  • Malalignment Test (MAT): Draw mechanical axes and knee joint lines. Measure the mechanical angular parameters - mLDFA and MPTA

Video Summary[edit | edit source]

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Annotations:
  • 00:08 Mechanical Axis Deviation (MAD)
  • 02:20 Varus and valgus limb alignment
  • 04:34 Malalignment Test and an example
  • 11:56 Tibial uniapical deformity example
  • 26:50 CORA

Malalignment tests[edit | edit source]

Fig. 7a. Malalignment test 1, with normal joint angle ranges.
MAT 1

If MAD exceeds normal range and (MPTA < 85° (tibial varus deformity) or mLDFA > 90° (femoral varus deformity) or both (tibia and femur varus deformity)), it is a varus malalignment of the limb (Fig. 7a)

Fig. 7b. Malalignment test 2, with normal joint angle ranges.
MAT 2

If MAD exceeds normal range and (MPTA > 90° (tibial valgus deformity) or mLDFA < 85° (femoral valgus deformity) or both (tibia and femur valgus deformity)), it is a valgus malalignment of the limb (Fig. 7b)

Fig. 7c. Malalignment test 3, with normal joint angle ranges.
MAT 3

If MAD exceeds normal range and  varus JLCA > 2°, it is varus malalignment due to deformity in knee joint. If MAD exceeds normal range and  valgus JLCA > 2°, it is valgus malalignment due to deformity in knee joint (Fig. 7c)

Malorientation test[edit | edit source]

Fig. 7d
Malorientation Test (MOT)

Draw mechanical axes and draw proximal femur joint lines and distal tibia joint lines. Measure the LPFA and LDTA angles. If they are not in normal range, there is malorientation in the hip joint or ankle joint or both (Fig. 7d).

Malalignment (MAT) is Malorientation (MOT) for the knee joints.

Malorientation of the ankle or hip joints usually leads to minimal or no MAD because the deformity apex is at or near the ends of the mechanical axis of the lower limb (refer Fig. 7d)

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