Background: The origin of femoral maltorsion is often unknown. However, defining the origin of the rotation of the femoral maltorsion can be useful for establishing the most suitable point to do an external derotational osteotomy. Previous studies have not considered the femoral diaphysis in their investigations of the origin of the deformity. The study of the whole morphology of the femur with 3D volumetric tools, including the femoral diaphysis can contribute to a better understanding of the behavior of femoral maltorsion. Methods: An atypical case of unilateral femoral anteversion was selected. Both femurs were used to obtain 3D bio-models. The mirror image of the asymptomatic side was obtained and overlapped with the symptomatic femur. The Hausdorff–Besicovitch method was used to evaluate the morphologic discrepancies (in mm) between the two femurs in three zones: (1) the femoral neck, (2) the proximal diaphysis, and (3) the distal diaphysis. The differences between the two femurs were analyzed and its correlation was statistically defined using a lineal regression model. Results: The deformity in the distal diaphysis increased from the supracondylar area until the apex of the antecurvatum angle (R2 = 0.91) and then decreased until the base of the femoral neck (R2 = (−0.83)), to finally increase significantly in the femoral neck area (R2 = 0.87). All of the correlations were statistically significant (p-value ˂ 0.001). Conclusion: The femoral maltorsion originates in the supracondylar area and its rotational axis is the longitudinal axis of the femoral diaphysis. Even though the deformity affects the femoral diaphysis, its clinical relevance is much higher in the femoral neck since the rotational axis passes through its base. Thus, the osteotomy can be conducted along all of the femoral diaphysis as long as it is done perpendicular to it.

Background: Mirroring the image of the affected side is a widely used technique for surgical planning in orthopedic surgery, especially for fractures and custom-made prostheses. Our objective is to evaluate the three-dimensional symmetry of the femurs using finite element analysis and manual alignment. Methods: Using the computed tomography of 15 patients without lower limb pathology, 30 3D biomodels of their femurs were obtained. The error obtained through image manipulation was calculated and broken down into a rendering error and a manual overlay error. The Hausdorff–Besicovitch method was applied to obtain the total asymmetry. The manipulation error was theb subtracted from it to obtain the intrapersonal asymmetry. Results: The mean intrapersonal asymmetry was 0.93 mm. It was obtained by subtracting the error derived from rendering and alignment of 0.59 mm (SD 0.17 mm) from the overall mean error of 1.52 mm (SD 1.45). Conclusions: Intrapersonal femoral asymmetry is low enough to use the mirror image of the healthy side as a reference for three-dimensional surgical planning. This type of planning is especially useful in deformity surgery when the objective of the surgery is not to restore only one specific parameter but to obtain a general functional morphology when a healthy contralateral femur is available.

Purpose To quantify the risk of perioperative and postoperative complications of derotational femoral and/or tibial osteotomies in patellofemoral disorders (anterior knee pain and patellar instability) in adolescents and active young patients. Methods MEDLINE, EMBASE, Cochrane and Scopus databases were used to identify studies published from database inception and June 30, 2021. Meta-analysis was performed to pool the rates of complications related to femur and tibia osteotomies. Values of proportion of complications were expressed as proportions and 95% conidence intervals (CI) and then transformed using a Freeman Tukey double arcsine transformation. Meta-regression was used to explore factors that potentially may inluence on heterogeneity such as year of publication, quality of the included studies and site of the osteotomy. ResultsThe 22 studies identiied included a total of 648 derotational osteotomies in 494 patients. Studies consisted of 20 case series (non-comparative) and 2 comparative observational non-randomized cohorts. Tibial osteotomies showed higher risk of complications than femoral osteotomies (random pooled prevalence 9%; 95% CI 4-15% versus 1%; 95% CI 0-5%, respectively, p < 0.01). The meta-regression analysis of the articles showed that the only parameters responsible of the variance in number of complications were the osteotomy site. Conclusions Derotational femoral and/or tibial osteotomy is a safe surgical procedure in the treatment of patellofemoral disorders (anterior knee pain and patellar instability) in adolescents and active young people. Level of evidence IV.

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