Impact of systematic ultrasound of the knee on the rheumatologist’s clinical decision in patients consulting for knee pain

This clinical practice study aimed to determine whether the results of systematic US in patients with knee pain modified the rheumatologist’s choices concerning diagnostic management and therapy. Patients consulting for non-traumatic knee pain, with recent radiography of the knee, were consecutively included over 9 months. After the radio-clinical assessment, the rheumatologist made a principal diagnosis concerning the knee pain and defined the therapeutic management and a complementary imaging strategy if necessary. US of the painful knee was then done in accordance with the reference protocol with the operators blinded to the clinical results. After reading the US report, the rheumatologist re-evaluated his/her diagnostic and therapeutic approach and the complementary exploration strategy. In the 100 patients included (mean age = 62.9 ± 18.5 years, duration of knee pain = 14.4 ± 8.1 months) with a majority of knee osteoarthritis (61 %), the diagnosis was clarified or modified after the US in 31 % of cases (calcium pyrophosphate deposition arthropathy and tendinitis principally), which led to an intensification of therapy in 15 % of cases and a de-escalation in 5 % of cases. These changes mainly concerned injectable treatments. The US of the painful knee resulted in few changes in imaging prescriptions (6 %), and this was not significant for the number of MRIs requested. In real-life practice in rheumatology, systematic US of the knee clarified the initial clinical diagnosis in almost one-third of cases, but did not significantly modify the therapeutic management, which remained symptomatic, and did not reduce the number of other imaging examinations after the initial radio-clinical assessment.