The Role of Ultrasound Versus Radiography in Knee Osteoarthritis: A Bilateral Comparative Study

Knee osteoarthritis (OA) is traditionally evaluated using conventional radiography (Rx), which is limited to assessing structural bone changes and provides only an indirect measure of cartilage status through joint space width (JSW). Musculoskeletal ultrasonography (US) allows direct visualization of cartilage, marginal osteophytes, meniscal extrusion, and joint effusion, but its added value over standard radiography in bilateral knee assessment remains incompletely characterized. This observational, cross-sectional study prospectively included 30 symptomatic patients (60 knees; 24 women; median age 69 years, range 56-85) with clinically diagnosed knee OA, all evaluated by bilateral weight-bearing radiography and standardized US. Non-parametric tests were used (p < 0.05). Ultrasound detected marginal osteophytes more frequently than radiography in both knees (86.7% versus 56.7% on the left, p = 0.003; 83.3% versus 63.3% on the right, p = 0.014), with no osteophyte identified by radiography alone. Anterior femoral US cartilage thickness did not correlate with radiographic tibiofemoral medial JSW. Meniscal extrusion was associated with medial JSW narrowing in the right knee (p = 0.024), and joint effusion occurred only in knees with ultrasound-detected osteophytes (p = 0.003 both knees). Ultrasonography provides complementary structural and mechano-inflammatory information beyond radiography and may support a multiparametric characterization of knee OA.