Sonographic evaluation of hip joint effusion in osteoarthritis with correlation to radiographic findings.

Purpose: Hip joint effusion is expected in rapidly destructive osteoarthritis, a diagnosis often only made retrospectively at the end stage of the disease. This study assesses whether the presence of an effusion identified during routine ultrasound-guided hip injection may suggest a more aggressive process such as rapidly destructive osteoarthritis.

Methods: After the observation of 10 index cases of rapidly destructive osteoarthritis in patients who presented with a joint effusion on ultrasound, we retrospectively reviewed 94 hips from 89 patients who underwent ultrasound-guided hip injection for pain. Preinjection longitudinal ultrasound images of the anterior capsule adjacent to the femoral neck and inferior to the femoral head were reviewed to determine if a joint effusion was present and the size of the effusion if one was there. Comparison of effusion size was then made between those hips that had a clinical and radiographic diagnosis of osteoarthritis and those who had rapidly destructive osteoarthritis by comparing the severity of joint effusion, if one was present.

Results: Patients with rapidly destructive osteoarthritis were more likely to have a large joint effusion 60% (3/5) than were those with osteoarthritis 6.7% (6/89) (p = 0.013).

Conclusions: Large joint effusions identified sonographically correlate well with radiographic findings of rapidly destructive osteoarthritis. Given rapid onset and severity of the disease, when a large joint effusion is identified on routine hip intervention, patients should be forewarned of the potential for this disease process.