Tibial subchondral trabecular volumetric bone density in medial knee joint osteoarthritis using peripheral quantitative computed tomography technology.

OBJECTIVE Knee osteoarthritis (OA) is an organ-level failure of the joint involving pathologic changes in articular cartilage and bone. This cross-sectional study compared apparent volumetric bone mineral density (vBMD) of proximal tibial subchondral trabecular bone in people with and without knee OA, using peripheral quantitative computed tomography (pQCT). METHODS Seventy-five individuals with mild or moderate medial compartment knee OA and 41 asymptomatic controls were recruited. Peripheral QCT was used to measure vBMD of trabecular bone beneath medial and lateral tibiofemoral compartments at levels of 2% and 4% of tibial length, distal to the tibial plateau. RESULTS There was no significant difference in vBMD beneath the overall medial and lateral compartments between the 3 groups. However, in the affected medial compartment of those with moderate OA, lower vBMD was seen in the 2 posterior subregions compared with controls and those with mild knee OA, while higher vBMD was seen in the anteromedial subregion. Beneath the unaffected or lesser affected lateral compartment, significantly lower vBMD was seen at the 2% level in the anterior and lateral subregions of those with moderate disease. Volumetric BMD ratios showed relatively higher vBMD in the medial compartment compared with the lateral compartment, but these ratios were not influenced by disease status. CONCLUSION Subregional vBMD changes were evident beneath the medial and lateral compartments of those with moderate medial knee OA. Of import, the posterior subchondral trabecular regions of the medial tibial plateau have markedly lower vBMD.