Background The association between hand (HOA) and knee osteoarthritis (KOA) has been questioned. Current evidence is contradictory.

Objectives To study the prevalence of radiographic HOA in a large KOA population, and its cross-sectional association to knee OA radiographic severity.

Methods Baseline data were obtained from an international 3-year prospective, multicenter, randomized, controlled trial comparing the structural effect of strontium ranelate to placebo in KOA. Inclusion criteria were: a diagnosis of OA according to ACR criteria, knee pain >40mm on a visual analog scale, OA atmedial compartment witha Kellgren-Lawrence (KL) grade 2 or 3and a minimal joint space width (JSW) of 2.5 to 5mm. Fixed-flexion postero-anterior (PA) radiographs of both knees in standing position every year and PA radiographs of each hand at baseline and endpoint were performed. Minimal JSW was centrally measured using a semi-automated standardized method. Hand radiographs were graded by 2 readers using KL (range 0-128), Kallman (0-204) and Verbruggen scoring methods. Radiographic HOA was defined as 2 or more joints at a KL2 or more. Statistics: Student T test, and Pearson correlation coefficient.Only the 1371 patients having at least 2 knee radiographs were analyzed.

Results 1360 patients had hand radiographs at baseline. 999 (73%) had HOA (HOA+). In HOA+, the mean age was 64 years, 71% were female, mean body mass index 29.6. HOA+ were older (5yrs), with a higher percentage of female (p=0.04), with no difference on BMI compared to non HOA patients (p=0.12). Mean knee JSW was 3.44 versus 3.66mm (p<0.001), and there was slightly more KL3 knees (40% vs 34%; p=0.047) in HOA+ compared to non HOArespectively. Conversely, global hand KL and Kallman scores were higher in KL3 KOA patients (22.5 vs 20.2; p=0.01 and 27.0 vs 23.6; p=0.02respectively), compared to KL2 patients. There was no difference for the Verbruggen score (14.7 vs 13.6, p=0.32). Pearson analyses did not showed linear correlations between knee JSW and hand KL score (r=0.123) or between knee and hand KL scores (r=0.085).

Conclusions Our data indicates a very high prevalence of radiographic HOA in a symptomatic KOA population, much more than expected. KOA is radiographically more severe in case of HOA. Conversely, HOA is more severe in the more severe KOA patients (KL3).

Disclosure of Interest E. Maheu Grant/Research support from: from Institut de Recherche International Servier, C. Cadet Grant/Research support from: from Institut de Recherche International Servier, F. Berenbaum Grant/Research support from: From Institut de Recherche International Servier