Background Osteoarthritis is the most common form of arthritis and a major socioeconomic burden. Our study is the first to explore the association between serum microRNA levels and the development of severe osteoarthritis of the knee and hip joint in the general population. Methods We followed 816 Caucasian individuals from 1995 to 2010 and assessed joint arthroplasty as a definitive outcome of severe osteoarthritis of the knee and hip. After a microarray screen, we validated 12 microRNAs by real-time PCR in the entire cohort at baseline. Results In Cox regression analysis, three microRNAs were associated with severe knee and hip osteoarthritis. let-7e was a negative predictor for total joint arthroplasty with an adjusted HR of 0.75 (95% CI 0.58 to 0.96; p=0.021) when normalised to U6, and 0.76 (95% CI 0.6 to 0.97; p=0.026) after normalisation to the Ct average. miRNA-454 was inversely correlated with severe knee or hip osteoarthritis with an adjusted HR of 0.77 (95% CI 0.61 to 0.97; p=0.028) when normalised to U6. This correlation was lost when data were normalised to Ct average (p=0.118). Finally, miRNA-885-5p showed a trend towards a positive relationship with arthroplasty when normalised to U6 (HR 1.24; 95% CI 0.95 to 1.62; p=0.107) or to Ct average (HR 1.30; 95% CI 0.99 to 1.70; p=0.056). Conclusions Our study is the first to identify differentially expressed circulating microRNAs in osteoarthritis patients necessitating arthroplasty in a large, population-based cohort. Among these microRNAs, let-7e emerged as potential predictor for severe knee or hip osteoarthritis.

In a previous radiostereometric analysis (RSA) of the Lubinus SP II (Link, Hamburg, Germany), which is one of the most often used cemented hip stems worldwide, our research group detected a very small but statistically significant distal migration of -0.03±0.17 mm 2 years after surgery compared to the postoperative radiograph. Maximum subsidence occurred between 6 and 12 months. The implant appeared to have stabilized after 2 years. The mean value of maximum total point motion (MTPM) was 0.99±0.69 mm, which was detected 2 years after surgery. The purpose of this study was to analyze the migration pattern and to verify the predictive value of short-term RSA of the Lubinus SP II stem after 10 years. After a follow-up of 5 and 10 years, 38 and 27 out of 100 patients remained available for further assessment, respectively. No statistically significant implant translation or rotation was found along or about the axes of the global coordinate system 5 and 10 years after surgery with respect to the postoperative radiograph. Furthermore, the MTPM was stable in both follow-up periods. The results suggest that the Lubinus SP II hip stem is still stable 10 years after surgery, supporting that determining prognosis by short-term RSA follow-up of 2 years could be an appropriate tool for appraisal of implant behavior 10 years after surgery.