Objective To determine if clinical correlates of knee osteoarthritis(OA) affect likelihood of outcome to intra-articular steroid injections(IASI) in symptomatic knee OA.
Methods Men and women aged≥40 years with painful knee OA who participated in an open label trial of IASI completed questionnaires and clinical examination. OMERACT-OARSI criteria were used to assess response to therapy in the short-term(within 2-weeks). Among those who initially responded, those whose pain had not returned to within 20% of the baseline KOOS-pain score at 6-months were characterised as longer-term responders. Log binomial regression was used to examine factors associated with outcome.
Results 199 participants were included, of whom 146(73.4%) were short-term and 40(20.1%) longer-term responders. Compared to short-term non-responders, participants with medial joint-line tenderness(RR=1.42;1.10-1.82), medial & lateral joint-line tenderness(RR=1.38;1.03-1.84), patellofemoral tenderness(RR=1.27;1.04-1.55), anserine tenderness(RR=1.27;1.06-1.52) and a belief that treatment would be effective(RR/unit increase, [range 0-10]=1.05;1.01-1.09), were more likely to be short-term responders. Aspiration of joint fluid(RR=0.79;0.66-0.95) and previous ligament/meniscus injury(RR=0.63;0.44-0.91) were associated with a reduced risk of being a short-term responder. Compared to initial non-responders and those whose pain recurred within 6-months, participants with higher number of pain sites(RR/unit increase, [range 0-10]=0.83;0.72-0.97), chronic widespread pain(RR=0.32;0.10-0.98), perceived chronicity of disease(RR/unit increase, [range 0-10]=0.86;0.78-0.94) and a higher depression score(RR/unit increase, [range 0-21]=0.89;0.81-0.99) were less likely to be longer-term responders.
Conclusion Among patients with symptomatic knee OA, tenderness around the knee was associated with better short-term outcome to IASI. However, clinical-related factors did not predict longer-term response while those with chronic widespread pain and depressive symptoms were less likely to obtain longer-term benefit.