Table 2 Different HTO implants considered in the study (Groups IV to VII)

TomoFix sm (Group IV)

Titanium

Same fixation principle with the TomoFix std. Geometry adapted from the TomoFix std. to patient with small stature

ContourLock (Group V)

Titanium

Short spacer plate with large proximal part and angle stable multidirectional screws.

The proximal screws are monocortical and fixed in the cancellous bone and the distal screws are bicortical.

Activmotion (Group VI)

Titanium alloy

Internal fixator with eight monoaxial locking screws. The diaphyseal screws are bicortical while the epiphyseal are monocortical

FlexitSystem (Group VII)

Titanium alloy

T-shaped internal fixator, shorter than the TomoFix plates, with angle stable unidirectional screws. The proximal screws are monocortical and fixed in the cancellous bone and the distal screws are bicortical.