# Fixation Stability and Stiffness of Two Implant Systems for Proximal Femoral Variation Osteotomy
## 4 Discussion
One further limitation of the study is the simplification of the loads that actually affect the musculoskeletal system. No combined load scenarios were applied, which do not fully correspond to reality, but facilitates the interpretation and comprehensibility of the results. However, the simulation of a sideways fall on the greater trochanter region is a frequently used method to examine the load capacity in the area of the osteotomy gap [14; 15]. The results of this study showed that it is not possible to make a statement about possible intra- and postoperative complications. Blood loss, operation time, delayed union, implant loosening, and wound infections are typical parameters that should be evaluated in further comparative in vivo studies. Radiographic analyses of changes in containment should also be evaluated. In regard to existing studies, we expect comparable good results for these parameters [9; 11; 12]. Implant-related fractures along the two different implant systems (blade plate versus screw side plate) have been evaluated [11]. A previous study showed that no observed significant differences [11] may support our results on stiffness and stability. Therefore, differences in the design of the plates do not necessarily lead to significant differences in stability, even if we must await further studies with our two implant systems in vivo before making a definitive statement. The correlation between surgeon experience and operative results is well explored [12]. All osteectomies in this study were performed by a well-experienced senior surgeon to prevent learning curve effects. In a study analyzing CBP versus fixed angled blade plate, trainee surgeons were found to have preference for CBP when learning proximal femoral osteotomy [11]. In the present study, we decided to use the CBP for our trainee surgeons in their first year. Severe cases, such as osteopororotic bones and the use of PL, are reserved to senior surgeons in our department. In conclusion, the average torsional stiffness of the locking plate group was higher than for the cannulated blade plate group. Differences in internal and external rotations were seen between the two groups, but they were not significant. Using the tested implants in severe osteopororotic bones might show other results. Therefore, it might be helpful to use the locking plate system in osteopororotic bones and in cases of revision operations where stability is of critical focus. Conceptualization, K.R. and F.G.; methodology, K.R., F.G., B.W., and M.E. ; software, M.S. and B.W. ; validation M.S. and B.W. ; operation/implantation, F.G. and P.P. ; biomechanical testing, M.S. and B.W. ; data curation, B.W. and M.S. ; writing--original draft preparation, K.R., B.W., and M.S. ; writing--review and editing, K.R., B.W., and M.S. ; visualization, B.W. and M.S. ; supervision, B.W. ; funding acquisition, F.G. All authors have read and agreed to the published version of the manuscript. This research received no external funding. We thank [PERSON] from OrthoPediatrics (now NuVasive Germany GmbH, Bremen, Germany) for supporting our study with the used implants and sawbones. We acknowledge support by the German Research Foundation (DFG) and the Open Access Publication Fund of Hannover Medical School (MHH). All authors declare that we received implants and sawbones from [PERSON], OrthoPediatrics, Warsaw, IN, USA, for this study. The sponsors had no role in the design, execution, interpretation, or writing of the study.