Statistical analysis The data will be analysed according to the intention-to-treat principle. Standard statistical techniques will be used to describe characteristics of patients in both groups. We will compare baseline characteristics in the two treatment groups and if incomparability appears, we will in secondary analysis adjust for differences. The primary outcome, significant pain relief will be compared with the analysis of variance for repeated measures. If adjustment for possible baseline incomparability is needed, analysis of covariance will be done. Since we expect the difference between the two groups will particularly become evident at 3, 6 and 12 months, the analysis will also be performed at these time points.