Region specific Raman spectroscopy analysis of the femoral head reveals that trabecular bone is unlikely to contribute to non-traumatic osteonecrosis

Abstract

Non-traumatic osteonecrosis (ON) of the femoral head is a common disease affecting a young population as the peak age of diagnosis is in the 40 s. The natural history of non-traumatic ON leads to a collapse of the femoral head requiring prosthetic replacement in a 60% of cases. Although trabecular bone involvement in the collapse is suspected, the underlying modifications induced at a molecular level have not been explored in humans. Here, we examine changes in the molecular composition and structure of bone as evaluated by Raman spectroscopy in human end-stage ON. Comparing samples from femoral heads harvested from 11 patients and 11 cadaveric controls, we show that the mineral and organic chemical composition of trabecular bone in ON is not modified apart from age-related differences. We also show that the molecular composition in the necrotic part of the femoral head is not different from the composition of the remaining ‘healthy’ trabecular bone of the femoral head. These findings support that quality of trabecular bone is not modified during ON despite extensive bone marrow necrosis and osteocyte death observed even in the ‘healthy’ zones on histological examination.

Bone Microarchitecture and Biomechanics of the Necrotic Femoral Head

“…Pascart T et al . 22 detected a decrease in proteoglycan content in the sclerotic region, which was linked to an increase in bone remodelling. In addition, their histological examination showed the presence of woven bone corresponding to rapid disorganised new bone apposition.…”

Effects of sclerotic changes on stress concentration in early‐stage osteonecrosis: A patient‐specific, 3D finite element analysis

“…Several authors have conducted experiments using resected femoral heads with end‐stage ONFH to explore the mechanism of femoral head collapse. Wang et al showed that the micromechanical properties of bone trabeculae in collapsed femoral heads with ONFH did not differ significantly between the necrotic zone and the healthy zone.…”

“…Wang et al showed that the micromechanical properties of bone trabeculae in collapsed femoral heads with ONFH did not differ significantly between the necrotic zone and the healthy zone. Using Raman spectroscopy analyses, Pascart et al also demonstrated that the molecular composition and structure of the trabecular bone were not modified in end‐stage ONFH. Although clarifying the mechanism of collapse would ideally involve a variety of experiments, it is impossible to obtain a whole femoral head before collapse.…”

“…The elastic modulus of bone in collapsed ONFH has been reported to be markedly lower (72%) than in samples from normal femoral heads . However, the biomechanical properties of femoral heads with osteonecrosis have been reported to be similar in the necrotic and viable zones in both nanoindentation testing and Raman spectroscopy analyses . Since this study used CT data from cases of early‐stage osteonecrosis, the elastic moduli of both the necrotic and viable zones were determined based on CT density values.…”

“…First, the apparent bone mineral density (p in g/cm 3 ) of each element was determined using Hounsfield units. The elastic modulus (E [MPa]) of each element was then determined from the apparent bone density value using the equations proposed by Keyak et al Since the biomechanical properties of ONFH have been reported to be similar in necrotic and viable zones, the elastic modulus of necrotic zones was also determined from CT density values. The Poisson's ratio of the pelvis, the femur, and necrotic zones was 0.40 .…”