The aim of this study is to establish the efficacy and duration of effect of intra-articular (IA) infliximab vs intravenous infliximab vs current standard care (IA steroid injections) in seronegative oligoarthritis. All patients will have seronegative arthritis affecting less than 5 joints but including at least one knee. 10 patients will receive IA infliximab injections to the affected knee, 10 will receive IA steroid injections to the affected knee and 10 will receive a course of intravenous infliximab. Patients will not be aware of their group as this is a placebo-controlled study.