Assessment of the effects of core decompression on the patho-biomechanics of the femoral head in avascular necrosis: A biomechanical perspective

Background

Avascular necrosis (AVN) of the femur head (FH) is an incapacitating disease caused by chronic overconsumption of alcohol and corticosteroids. AVN impairs blood circulation to the FH, causing varying degrees of cell death. AVN progressively reduces the macroscopic mechanical strength of the bone's necrotic area, leading to FH collapse.

Material and method

This study aims to comprehend the efficacy of core decompression (CD) on biomechanical, microstructural, and compositional determinants of bone quality. In this work, 30 FH are taken of the patients who underwent total hip replacement due to AVN. These 30 samples are categorized into two groups (15 each), i.e. with CD (individuals who underwent core decompression treatment at the early stages of AVN) or without CD (individuals who did not receive any invasive therapy in the past following a hip fracture due to AVN). Bone morphometry, biomechanical, material, and nano-level properties are analyzed across necrotic and sclerotic zones of FH through micro-CT scanning, histo-pathology, Uni-axial compression, and Nano-indentation tests.

Results

The obtained results demonstrated a notable increment in bone volume fraction, ultimate strength, and osteocytes of the sclerotic zone of both groups compared to the necrotic region. A significant improvement was observed in the quality of trabecular bone at multiple scales of human bone tissue including higher bone volume fraction (22.87 %, P < 0.05), increased Young’s modulus (28.80 %, P = 0.0183) and increment in Mineral/Matrix ratio (53.20 %, P = 0.0429) and reduction in % of empty lacunae (22.39 %, P < 0.01) in the necrotic region of patients with core decompression compared to patients without any invasive treatment.

Conclusion

The optimum core decompression enhances the stability of the femur head by increasing the macroscopic mechanical strength of necrotic bone and decreasing the strength of sclerotic bone. This brings the strength of both bones nearly equal, further reducing the stress gradient and probability of collapse of the AVN femur head.