Validity and Reliability of Measuring Femoral Anteversion and Neck-Shaft Angle in Patients with Cerebral Palsy

The aim of this study was to provide a preliminary evaluation of the possible effect that femoral version may have on the bearing equilibrium conditions developed on the medial tibiofemoral compartment. A digital 3D solid model of the left physiological adult femur was used to create morphological variations of different neck-shaft angles (varus 115, normal 125, and valgus 135 degrees) and version angles (−10, 0, and +10 degrees). By means of finite element modeling and analysis techniques (FEM-FEA), a virtual experiment was executed with the femoral models aligned in a neutral upright position, distally supported on a fully congruent tibial tray and proximally loaded with a vertical only hip joint load of 2800 N. Equivalent stresses and their distribution on the medial compartment were computed and comparatively evaluated. Within our context, the neck-shaft angle proved to be of rather indifferent influence. Reduction of femoral version, however, appeared as the most influencing parameter regarding the tendency of the medial compartment to establish its bearing equilibrium towards posteromedial directions, as a consequence of the corresponding anteroposterior changes of the hip centre over the horizontal tibiofemoral plane. We found a correlation between femoral anteversion and medial tibiofemoral compartment contact pressure. Our findings will be further elucidated by more sophisticated FEM-FEA and by clinical studies that are currently planned.

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The effect of valgus and varus femoral osteotomies on measures of anteversion in the dog

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.3415/vcot-16-09-0138 ◽

2017 ◽

Vol 30 (03) ◽

pp. 184-190 ◽

Cited By ~ 3

Author(s):

Rachel Adams ◽

Brad Gilleland ◽

Farrah Monibi ◽

Samuel Franklin

Keyword(s):

Repeated Measures ◽

Three Dimensional ◽

Frontal Plane ◽

Femoral Anteversion ◽

Coxa Vara ◽

Neck Shaft Angle ◽

Repeated Measures Analysis ◽

Shaft Angle ◽

Coxa Valga ◽

Head Neck

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.

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