The effect of osteoarthritis on the regional anatomical variation of subchondral trabecular bone in the femoral head

Abstract

Background: The subchondral trabecular bone is located deep inside the articular cartilage, with the subcapital region carrying up to 70% of the diurnal loads occurring in the hip joint. This leads to severe regional anatomical variations of subchondral trabecular bone in the femoral head and the purpose of this study was to examine whether osteoarthritis affects these topographic characteristics.

Methods: 60 femoral heads were harvested during hip replacement and studied by osteopenetration at 8 pre-defined angles, at a penetration rate of 1mm/s. Twenty-eight of the donors underwent surgery due to osteoarthritis, whereas the remaining were trauma patients with hip fractures. To correlate these measurements to non-invasive data, all specimens were scanned by micro Computed Tomography (μCT) prior to experimentation. A cross-sectional area, perpendicular to the needle penetration pathway, was analyzed and the deviations compared to the recorded osteopenetration energy.

Findings: The experiments revealed significant topographical deviations in the trabeculae. These were more pronounced in the osteoarthritic samples which also required overall higher osteopenetration energy. A notable dependency of the directional bone strength to its cross-sectional characteristics was observed. Although the effect of "gender" on osteopenetration energy was proven to be significant, gender was not considered an independent variable in a regression model correlating osteopenetration energy to 2D trabecular bone density as this did not improve the value of the adjusted R(2).

Interpretation: The investigation provided refined insight into femoral head load-bearing capacity of patients suffering from osteoarthritis, as a comparison of osteoarthritic to healthy samples illustrated that subchondral trabecular bone in the femoral head region is subjected to increased remodeling and demineralization, reflected in higher osteopenetration values.

Keywords: Cancellous bone characteristics; Femoral head; Osteoarthritis; Osteopenetration.