Analysis of Bone Microarchitectural Changes and Structural Damage in Sickle Cell Disease-Induced Avascular Necrosis Using Raman Spectroscopy: Is there potential for medical management?

Abstract

Objectives: Bone failure due to avascular necrosis (AVN) is a complex pathological phenomenon. Analysis of molecular changes in the bone matrix may help to shed light on the disease process and guide management. This study aimed to explore changes in bone quality and structural damage caused by sickle cell disease (SCD)-induced AVN using Raman spectroscopy.

Methods: A total of 10 necrotic femoral heads were obtained from seven SCD patients who underwent total hip replacements. The femoral heads were cut in half and scanned using Raman spectroscopy in correlation with preoperative magnetic resonance imaging to identify necrotic and healthy control areas. Subsequently, samples were examined to determine changes in bone mineralisation, crystallinity, carbonate content, collagen cross-linking and mineral and collagen fibril orientation.

Results: Significant changes were observed in bone mineral content, mineral-to-organic content and collagen fibril orientation in necrotic compared to control areas (P ≤0.050).

Conclusion: The necrotic samples displayed severe structural damage and loss of mineral and organic contents. Similar Raman signals have been reported in other metabolic bone diseases such as osteoporosis, thereby potentially supporting the use of medical treatment in AVN to promote bone quality.

Keywords: Bone Density; Bone Mineralization; Bone Remodeling; Extracellular Matrix; Femur Head Necrosis; Osteonecrosis; Raman Spectroscopy; Sickle Cell Disease.

Figure 1

A: Photograph of the bisected femoral head of a patient with sickle cell disease-induced avascular necrosis showing necrosis in the subchondral area (arrow). B: Preoperative magnetic resonance imaging showing the same necrotic area as a hypointense signal (arrowhead).

Figure 2

Graphs comparing the acquired Raman spectra of (A) normal bone and (B) bone collected from femoral heads affected by sickle cell disease-induced avascular necrosis (N = 10). The normal bone shows peaks at 958 cm⁻¹ for phosphate, 1,070 cm⁻¹ for carbonate, 1,660 cm⁻¹ for amide I and 1,684 cm⁻¹ for amide II. It demonstrates the overall drop in spectra of necrotised bone.

Figure 3

Charts showing the average acquired Raman spectra from bone samples collected from femoral heads affected by sickle cell disease-induced avascular necrosis (N = 10). In comparison to healthy control areas, the necrotic areas showed (A) an increased carbonate-to-phosphate ratio, indicating a difference in bone crystallinity and transformation to a brittle matrix, (B & C) reduced phosphate-to-amide and carbonate-to-amide ratios, indicating a reduction in mineral relative to organic material, and (D) a reduced collagen crosslinking ratio, indicating increased collagen cross-linkage disruption. AVN = avascular necrosis.