Biomechanical evaluation of temporary epiphysiodesis at the femoral epiphysis using established devices from clinical practice.

The aim of this study is to compare biomechanical features of different devices used in clinical routine for temporary epiphysiodesis (eight-Plate® and FlexTackTM). The tested implants were divided into four different groups (eight-Plate® vs. FlexTackTM for lateral and anterior implantation) á 10 samples for testing implanted eight-Plate® vs. FlexTackTM in fresh frozen pig femora for maximum load forces (Fmax) and axial physis distance until implant failure (lmax). A servo hydraulic testing machine (858 Mini Bionix 2) was used to exert and measure reproducible forces. Statistical analyses tested for normal distribution and significant (p < 0.05) differences in primary outcome parameters. There were no significant differences between the eight-Plate® lateral group and the FlexTackTM lateral group for neither Fmax (p = 0.46) nor lmax (p = 0.65). There was a significant higher Fmax (p < 0.001) and lmax (p = 0.001) measured in the eight-Plate® group compared to the FlexTackTM group when implanted anteriorly. In anterior temporary ephiphysiodesis, eight-Plate® demonstrated superior biomechanical stability. At this stage of research, there is no clear advantage of either implant and the choice remains within the individual preference of the surgeon.