Mathematical Morphology Based Volumetric Analysis of Bone Density Around Implant in Post-Operational Follow-up of Per-Trochanteric Fractures

Abstract

Per trochanteric fractures are common in an ageing population with osteoporosis and account for about half of all hip fractures. Treatment of per trochanteric fractures with extramedullary or intramedullary implants is challenging especially in unstable fractures. In order to improve the mechanical anchorage of the screw and prevent re-operations, various attempts have been made to reinforce the fragile bone with polymer based injectable materials. However, volumetric control of delivered material and/or measurement of bone density in post-operative follow-up remains challenging. This study presents the basic principles of a new algorithm for CT based volumetric analysis of the bone density in the region adjacent to the implant in the femoral head in comparison to the non-operated hip. The method was also used to track long term bone density changes at3 to 6 months of follow up. Introduction. Per trochanteric fractures are common in elderly, and account for about half of all hip fractures (Hermann et al. 2012). Treatment of per trochanteric fractures with extramedullary or intramedullary implants is challenging because of poor bone quality, which eventually leads to reoperations in up to 5% of the cases mainly in unstable fractures. Special mechanical solutions are proposed to cope with the problem of implant anchorage (Aros et al. 2008). In order to improve the mechanical anchorage of the screw and prevent re-operations, various attempt shave been made to reinforce the fragile bone with polymer based injectable materials, such as polymethyl methacrylate (PMMA) (Stoffel et al., 2008; Gupta et al., 2012) or Calcium phosphate (CaP) (Mattsson and Larsson, 2004; Fuchs et al., 2019).Bioresorbable calcium sulphate/hydroxyapatite (CaS/HA) is reported as a promising solution of implant anchoring problem. The compressives trength of the material is higher than the cancellous. [...].