Summary
Objective: To determine whether femoral osteotomies that change frontal plane alignment without
affecting torsion influence anteversion and inclination.
Methods: Femurs without deformity were scanned to create three-dimensional reconstructions.
The femoral head-neck axis was identified by placement of a virtual intra-medullary
pin. A proximal osteotomy was simulated to create three conditions while keeping torsion
constant: Normal, Coxa Valga (neck-shaft angle increased by 12°), and Coxa Vara (neck-shaft
angle decreased by 12°). Femoral anteversion was measured from an axial image in all
three conditions. Femoral inclination was calculated for all conditions using the
neck-shaft and anteversion angles. Changes in anteversion and inclination were calculated
and compared using a one-way repeated measures analysis of variance. Distal femoral
osteotomies were then simulated with the native femurs, inducing 18° of distal varus
with no change to torsion. Changes in anteversion and inclination for the Normal and
Distal Varus conditions were calculated and compared by a paired t-test.
Results: Version changed by a mean of 13.9° (± 1.5; p <0.0001) from the Coxa Valga to Coxa
Vara conditions while inclination changed by a mean of 1.3° (± 0.39; p <0.01). Version
changed by a mean of 6.6° (± 0.7; p <0.0001) between the Distal Varus and Normal conditions
while inclination changed by a mean of –3.8° (± 0.75; p <0.001).
Clinical significance: Femoral version changes with changing frontal plane alignment even when torsion is
constant. This should be considered when correcting femoral deformities.
Keywords
Anteversion - osteotomy - angular limb deformity - femur - patellar luxation