This is a randomised, double-blind, multicentre equivalence study with active comparator, parallel group, to evaluate the efficacy and safety of Norspan® patches versus Tramadol in subjects with OA pain in hip, knee and/or lumbar spine, currently receiving sub-optimal analgesic treatment (defined as BS-11 score > 4) when treated with paracetamol 4000 mg/day or another analgesic at least comparable to this.~The study consist of 4 phases:~Run-in, Wash-out, Double blind and Follow-up
The primary objective of this equivalence study is to evaluate the efficacy of Norspan® patches versus Tramadol in subjects with chronic, moderate to severe osteoarthritis pain of the hip, knee and/or lumbar spine.~The secondary objectives are to evaluate the safety and general satisfaction for the patients in the two treatment groups.