Background Choline-stabilized orthosilicic acid (ch-OSA) was previously found to stimulate bone collagen formation in osteopenic women (1).

Objectives The aim of the present study was to evaluate the effect of ch-OSA on symptoms of knee osteoarthritis (OA) in a multicenter, randomized, double-blind, placebo-controlled, single joint study.

Methods Over 12 weeks, 166 patients with documented knee OA (K&L grade II and III) and a baseline knee pain score of moderate or moderately severe on a 5-point Likert scale, completed the study. The patients received daily either ch-OSA (n=87) or placebo (n=79). The mean age of patients was 61.9 years and 72% were women of which 98% were post-menopausal. Patients were allowed to take rescue medication (paracetamol) up to 48 hours prior to each clinical investigation. Symptoms of OA were evaluated in the target knee with the WOMAC index and Patient Global Assessment was measured on a 100 mm VAS. Biochemical markers of cartilage degradation i.e. C-telopeptide fragments of type II collagen (CTX-II) and cartilage oligomeric matrix protein (COMP), were analyzed.

Results No significant different effect of ch-OSA treatment was found compared to placebo on symptoms of knee OA in the total study population but a significant (p<0.05) improvement was found after 12 weeks treatment in men taking ch-OSA compared to men in the placebo group, respectively for WOMAC (ch-OSA: -18.3 mm, -43% vs. placebo: -7.3 mm, -17%), WOMAC pain (ch-OSA: -19.7 mm, -48% vs. placebo: -9.5 mm, -22%), WOMAC stiffness (ch-OSA: -22.1 mm, -48% vs. placebo: -5.6 mm, -13%) and WOMAC physical function (ch-OSA: -17.4 mm, -41% vs. placebo: -6.8 mm, -16%). A similar trend was observed in global assessment (ch-OSA: -25.3 mm, -50% vs. placebo: -17.3 mm, -34%). The change in biochemical markers was also significantly different (p<0.05) in men for both CTX-II (ch-OSA: +73.4 ng/mmol, +20% vs. placebo: +175 ng/mmol, +45%) and COMP (ch-OSA: -0.24 ng/mmol, -2% vs. placebo: +1.83 ng/mmol, +17%). Baseline levels of CTX-II were higher (<0.01) in women compared to men. Patients (women and men) with moderate baseline knee pain and K&L grade II, showed a significant improvement in WOMAC after 6 weeks treatment (ch-OSA: -16.3 mm, -55% vs. placebo: -7.1 mm, -22%).

Conclusions This study demonstrates that ch-OSA reduces pain and stiffness and improves physical function already after 12 weeks of treatment in men with symptomatic knee OA and is associated with decreased cartilage degradation. The difference in response to ch-OSA treatment between men and women may be explained by reported gender differences in the incidence and severity of knee OA (2) including higher levels of cartilage degradation products (3) which is confirmed in the present study. Longer ch-OSA treatment may therefore be needed in women to result in a clinical benefit and should be further investigated.

References

1. Spector et al. BMC Musculoskeletal Dis, 2008, 9:85.

2. Karsdal et al. BMC Musculoskeletal Dis, 2010, 11:125.

3. Srikanth et al. Osteoarthritis Cartilage, 2005, 13: 769.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.2826