Background/Purpose: to date diagnosis of knee osteoarthritis (OA) is based on clinical examination and radiological features. Our objetive was to evaluate the diagnostic test properties of ultrasound (US) for the detection of radiographic knee OA.

Methods: consecutive patients complaining of knee pain were included. Exclusion criteria were: younger than 18 years old, history of knee surgery or trauma, severe knee deformities and corticosteroid injection within the last 2 months. US examinations were performed by an experienced rheumatologist, blinded to clinical and radiological data, using a MyLab 70 machine (Esaote) provided with a multi-frequency linear transducer (4-13 MHz). Standardized scanning method was adopted in order to evaluate the following US abnormal findings: osteophytes (protrusions at the joint margin seen in two planes and visualized as either proximal or distal to the joint) and degenerative femoral hyaline cartilage involvement (presence of at least two of the following: loss of sharpness of the cartilage margins, loss of homogeneity of the cartilage layer and cartilage thinning focal or extend to the entire cartilaginous layer). Weight-bearing anteroposterior (AP) and lateral knee radiographs were read by an experienced rheumatologist, blinded to the clinical and US data, who determine the presence or absence of radiological degenerative changes and classified the severity of knee OA using Kellgren-Lawrence (KL) grading scale.

Results: 281 patients (mean age 64 ± 17 years, 173 (61,6%) female) were included for a total of 322 knees evaluated (41complained of bilateral knee pain). Both the presence of osteophytes and/or femoral hyaline cartilage involvement detected by US were more frequent in those knees with radiographic changes indicative of OA regardless severity acording KL grading scale (Table 1). Table 2 shows the diagnostic test properties of the US abnormal findings for the detection of knee OA using radiological data as reference method.

Conclusion: US demonstrate an excellent sensitivity with an adequate specificity for the detection of radiographic knee OA. US femoral hyaline cartilage involvement and/or US osteophytes showed the best sensitivity while isolated US osteophytes showed the best specificity. US could be used in patients with knee pain when OA is suspected. Table 1. Frequency of the US abnormal findings according radiographic features of knee OA.

Table 2. Diagnostic test properties of the US abnormal findings for the detection of knee OA using radiological data as reference method.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/radiographic-knee-osteoarthritis-in-patients-complaining-of-knee-pain-ultrasound-features/