Cross-sectional DXA and MR measures of tibial periarticular bone associate with radiographic knee osteoarthritis severity

SummaryObjectiveWe evaluated the relationship of medial proximal tibial periarticular areal bone mineral density (paBMD) and trabecular morphometry and determined whether these bone measures differed across radiographic medial joint space narrowing (JSN) scores.Methods482 participants of the Osteoarthritis Initiative (OAI) Bone Ancillary Study had knee dual X-ray absorptiometry (DXA) and trabecular bone 3T magnetic resonance imaging (MRI) exams assessed at the same visit. Medial proximal tibial paBMD was measured on DXA and apparent trabecular bone volume fraction (aBV/TV), thickness (aTb.Th), number (aTb.N), and spacing (aTb.Sp) were determined from MR images. Radiographs were assessed for medial JSN scores (0–3). We evaluated associations between medial paBMD and trabecular morphometry. Whisker plots with notches of these measures versus medial JSN scores were generated and presented.ResultsMean age was 63.9 (9.2) years, BMI 29.6 (4.8) kg/m2, and 53% were male. The Spearman correlation coefficients between DXA-measured medial paBMD and aBV/TV was 0.61 [95% confidence interval (CI) 0.55–0.66]; between paBMD and aTb.Th was 0.38 (95%CI 0.30–0.46); paBMD and aTb.N was 0.65 (95%CI 0.60–0.70); paBMD and aTb.Sp was −0.65 (95%CI −0.70 to −0.59). paBMD and the trabecular metrics were associated with medial JSN scores.ConclusionThe moderate associations between periarticular trabecular bone density and morphometry and their relationship with greater severity of knee OA support hypotheses of remodeling and/or microscopic compression fractures in the natural history of OA. Longitudinal studies are needed to assess whether knee DXA will be a predictor of OA progression. Further characterization of the periarticular bone in OA utilizing complementary imaging modalities will help clarify OA pathophysiology

Risk of knee osteoarthritis over 24 months in individuals who decrease walking speed during a 12-month period: Data from the osteoarthritis initiative

Objective. To assess the association between change in walking speed over a 12-month period and risk of developing radiographic knee osteoarthritis (rKOA) over a 24-month period. Methods.We included participants without rKOA from the Osteoarthritis Initiative. Change in walking speed was determined from a 20-m walk assessment, calculated using walking speed at 12-month followup minus baseline speed and/or 24-month followup walking speed minus 12-month speed. Incident rKOA was defined as progressing to Kellgren-Lawrence arthritis grading scale ≥ 2 within 24 months (i.e., incidence between 12 and 36 mos or 24 and 48 mos). Self-reported significant knee injury during the exposure period, age, body mass index (BMI), and Physical Activity Scale for the Elderly (PASE) score were adjusted for analytically. Results. We included 2638 observations among 1460 unique participants (58% women; aged 59 ± 9 yrs, range 45-79). The mean change in walking speed over 12 months was 0.001 ± 0.13 m/s (range -0.6271 to 1.4968). About 5% of the sample (n = 122) developed rKOA over a 24-month period. After controlling for significant knee injury, age, BMI, and PASE score, we found an 8% relative increase in risk of developing rKOA for every 0.1 m/s decrease in walking speed over a 12-month period (risk ratio 1.08, 95% CI 1.00-1.15, p = 0.05). Conclusion. Evaluating change in speed over a 12-month period using a 20-m walk test may be useful in identifying individuals at increased risk of developing rKOA over the subsequent 24 months. Identification of patients at high risk for developing rKOA would allow medical providers to implement early interventions to maximize joint health