Guided growth for correction of rotational deformities has been reported in several preclinical and clinical studies. Different adverse effects, like growth retardation, articular deformities, and rebound effect have been reported. We have tested a novel plate concept (RotOs PlateTM) intended for the correction of rotational deformities of long bones by guided growth in a porcine model. The plate has sliding screw holes intended to allow for longitudinal growth. Fourteen skeletally immature female pigs were included in the study in a paired design. Mean duration of intervention was 88 days (83–98). CTscans and X-rays were performed at plate insertion and removal. From the CTscans, 3D-models of the left and right femora were made and used for measuring the achieved rotation. Three pigs were excluded for reasons not related to the plate design. The plates rotated as intended in all pigs. In two pigs, there was a cut-out of the proximal screw on the lateral side. Data from these two pigs were included in the results. We observed a mean difference in rotation between the left and right femur of 5.7° in the external direction (CI:​ 3.7°−7.7°). No statistically significant deformities in the coronal and sagittal plane were observed. The plate worked as intended, that is, the intended rotation was achieved.

Clinical Significance:​ This large animal study shows promising results for the feasibility of the method. It is an important first step in validating the technique and detecting possible adverse effects before clinical studies.