Relationship of subchondral bone mineral density to progression of knee osteoarthritis

Abstract

Purpose: to assess the relationship of bone mineral density (BMD) of the subchondral femoral and tibial bones with the progression of knee osteoarthritis (OA) during 1 year of follow-up. Methods: the prospective study included 185 women (40-75 y.o) with Kellgren-Lawrence stage II-III knee OA (ACR). The average age was 59.2±7.4 y.o, body mass index (BMI) 27.7±4.4 kg/m2, and disease duration 12±8.1 years. An individual map was filled out for each patient, including anthropometric indicators, anamnesis and clinical examination data, assessment of knee pain by VAS, concomitant diseases and therapy during the follow-up period. All patients underwent standard radiography of the knee joints, two-energy x-ray densitometry of the lumbar spine (L1-L4), femoral neck, and subchondral femoral and tibial bones. The method described by E. Murphy and C. Hulet was used to assess the BMD of the subchondral bone. Results: During the year of follow-up, the progression of knee OA was noted in 15 patients (group 1), in 170 - the stage of the disease remained the same (group 2). There were no differences in age, age of onset, and duration of the disease, when comparing the groups. However, group 1 had a higher BMI (31.9±5.8 and 27.3±4.1 kg/m2, p < 0.0001) and walking pain intensity (VAS) of 65.8±11.8 and 47.5±18.7 mm (p < 0.0003). More women from group 1 had concomitant diseases: arterial hypertension (93.3% and 71.8%, respectively, RR=1.3, 95% CI 1.1-1.53, p=0.05) and type 2 diabetes (33.3% and 12.9%, RR=2.57, 95% CI 1.14-5.82, p=0.04); they were more likely to receive intra-articular injections of glucocorticoids in the knee joints (57.1% and 30.8%, RR=1.85, 95% CI 1.09-3.14, p=0.05). There were no intergroup differences in absolute values of the axial skeleton BMD: in L1-L4 (0.95 [0.92;1.25] and 0.93 [0.81;1.03], p > 0.05) and in the femoral neck (0.83 [0.69;1.2] and 0.78 [0.71;0.89], p > 0.05). When assessing the BMD of the subchondral divisions of the lateral (0.79 [0.54;0.93] and 0.75 [0.64;0.88], p > 0,05) and medial (0.89 [0.76;1.01] and 0.82 [0.68;0.96], p > 0,05) tibial condyles, comparable data were also obtained, with a tendency to higher indicators in patients with progression of knee OA (group 1). Statistically significant higher BMD values of the subchondral femur were found in group 1. The BMD of the lateral femoral condyle in group 1 was 1.09 [0.74;1.26] and in group 2 - 0.87 [0.75;1.0], p=0.04. The BMD of the medial femoral condyle in group 1 was 1.03 [0.96;1.13] and in group 2 - 0.86 [0.73;1.07], p=0.03. Correlation analysis confirmed the relationship between radiological progression of OA and BMD in the subchondral bone of the lateral (r = 0.32 and p=0.002) and medial condyles of the femur (r = 0.28 and p=0.02). Conclusions: higher BMD values in the subchondral femur can be considered as predictors of rapid radiological progression of OA. However, further study of this issue is required in multicenter long-term prospective studies.