Automated analysis of morpho-functional interbone parameters of the knee based on three dimensional (3D) surface data

Interbone parameters of the knee are of relevance in clinical practice, e.g. for the assessment of the functional anatomy of the individual patient. However, respective landmark identification and parameter derivation is mostly done manually. An automated analysis could enable the processing of large datasets, which could again enable the derivation of reference ranges or safe zones for various populations. Hence, the aim of this study was to automate the derivation of interbone parameters from 3D surface data of the knee and to evaluate the method’s robustness against a large dataset.A dataset of 414 knees from patients scheduled for total knee arthroplasty (TKA) was available for the analysis. For each case, knee surface models derived from CT as well as coordinates of the hip and ankle joint centers were available. Eight interbone parameters of the knee were identified in a literature research and an existing framework for morphological analysis of the knee was extended, in order to automatically calculate those parameters.The interbone analysis succeeded for 405 (97.8%) cases. After the exclusion of implausible cases, 373 (90.1%) parameter sets remained for statistical analysis.Differences in methodology, populations, imaging technique etc. complicate the comparison with values from the literature. However, for similar studies a good agreement in parameter values was found.The workflow presented proved robust against a large dataset of knee surface models. In the future, information about the bones’ relative position in the active, weight-bearing situation should be incorporated, in order to assess the impact on knee interbone parameters.