Background The clavicle presents a large variability in its characterizing sigmoid shape. Prominent and nonproperly fitting fixation plates (FP) cause soft tissue irritation and lead to hardware removal. It is therefore key in FP design to account for shape variations. Statistical shape models (SSMs) have been built to analyze a cluster of complex shapes. The goal of this study was to describe the anatomical variation of the clavicle using SSMs. Methods Two different SSMs of the clavicle were created and their modes of variation were described. One model contained 120 left male and female clavicles. The other model consisted of 76 left and corresponding right clavicles, 41 originating from men and 35 from women. Results The model of 120 left clavicles showed that 10 modes of variation are necessary to explain 95% of the variation. The most important modes of variation are the clavicle length, inferior-superior bow, and medial and lateral curvature. Statistically significant differences between male and female clavicles were seen in length, sigmoid shape, and medial curvature. Comparison in men between left and right revealed significant differences in length and medial curvature. For women, a statistically significant difference between left and right was only seen in the length. Conclusion Although the operative treatment of displaced midshaft clavicular fractures has clear benefits, the variable anatomy of the clavicle often makes it challenging for the surgeon to make the plate fit adequately. Based on the identified variability in the clavicle's anatomy, it seems unlikely that a clavicle plating system can fit the entire population.

Conventional anatomically contoured plates do not adequately fit most tibiae. This emphasizes the need for a more thorough morphological study. Statistical shape models are promising tools to display anatomical variations within a population. Herein, we aim to provide a better insight into the anatomical variations of the tibia and tibia plateau. Seventy-nine CT scans of tibiae were segmented, and a principal component analysis was performed. Five morphologically important parameters were measured on the 3D models of the mean tibial shapes as well as the −3SD and +3 SD tibial shapes of the first five components. Longer, wider tibiae are related to a more rounded course of the posterior column, a less prominent tip of the medial malleolus, and a more posteriorly directed fibular notch. Varus/valgus deformations and the angulation of the posterior tibia plateau represent only a small percentage of the total variation. Right and left tibiae are not always perfectly symmetrical, especially not at the level of the tibia plateau. The largest degree of anatomical variation of the tibia is found in its length and around the tibia plateau. Because of the large variation in the anatomy, a more patient-specific approach could improve implant fit, anatomical reduction, biomechanical stability and hardware-related complications.

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