Association between knee osteoarthritis and volumetric bone mineral density

Although patients with radiographic knee osteoarthritis (OA) have a higher areal bone mineral density (BMD) than non-OA individuals, their fracture risk was not significantly different. This study sought to define the association between radiographic knee OA and volumetric BMD.

We enrolled 944 men and 1506 women aged 40 years or older, selected randomly from Ho Chi Minh City, Vietnam. Knee radiographs were assessed using the Kellgren and Lawrence scale, with grades two or higher indicating knee osteoarthritis (OA). Areal bone mineral density (aBMD) at the femoral neck and lumbar spine was measured using DXA (Hologic Corp, USA). Trabecular and cortical volumetric bone density (vBMD) at the tibia bone were also measured using pQCT XCT2000 (Stratec, Germany). The difference in aBMD and vBMD between individuals with and without OA was quantified using effect size (ES) and 95 % confidence interval (CI).

The prevalence of radiographic knee OA in this cohort was approximately 31 % (n = 755), which increased with age. Compared to non-OA individuals, those with knee OA had higher femoral neck aBMD (ES = 0.04, 95 % CI: 0.02-0.05; P = 0.0002). However, knee OA patients had lower vBMD at the cortical tibia bone (ES = - 8.15, 95 % CI: -14.52 to -1.8; P = 0.01).

These data suggest that approximately a third of Vietnamese people aged 40 and over might have radiographic knee OA. The tibial cortical vBMD was significantly lower in persons with knee OA.