Distribution of effusion in knee arthritis as measured by high-resolution ultrasound

Abstract

Information about the distribution of effusion within the arthritic knee joint should be considered in selecting an anatomical approach for arthrocentesis. We recorded ultrasound measurements of fluid distribution in the knees of patients attending our clinic for knee injections under ultrasound guidance. In a cross-sectional observational study, we used high-resolution ultrasound (US) to record measurements of maximum fluid depth in the medial, midline and lateral regions of the suprapatellar pouch (SPP) in 46 patients with arthritis attending for routine US-guided injection of the knee. Mean fluid depth [in millimetres, (SD)] was significantly greater in the lateral SPP [9.2 (5.1)] than in the medial [6.5 (4.6)] or the midline [5.9 (3.7)] regions with the knee in relaxed full extension (p < 0.001 for comparison of lateral SPP with both midline and medial SPP). Small effusions were more commonly detected in the lateral SPP than elsewhere. In patients with painful knee arthritis, fluid distributes maximally to the lateral SPP in the extended knee. This has implications regarding the anatomical approach to arthrocentesis that clinicians should choose to perform and teach.

The Source of Fluid Deep to the Iliotibial Band: Documentation of a Potential Intra‐Articular Source

“…This observation suggests that the fluid seen in our asymptomatic runners was likely from the intra‐articular space [12]. When clinically indicated, the presence of fluid deep to the ITB should precipitate further evaluation of the knee joint [17]. Third, our results that the lateral synovial recess extends deep to the ITB are in line with the hypothesis of Nemeth and Sanders that irritation or inflammation of the lateral synovial recess may be pathoetiologic in some cases of ITBS [15,16].…”

Ultrasound of knee osteoarthritis: interobserver agreement and correlation with Western Ontario and McMaster Universities Osteoarthritis

“…The osteophytes are early signs of osteoarthritis and small osteophytes not detected on computed radiography may be diagnosed with high-resolution [30]. Ultrasound may allow visualization of small synovial effusion that more commonly detected in the lateral suprapatellar pouch with extended knee in patients with knee osteoarthritis [31]. Presence of hypertrophied synovium in patients with osteoarthritis is sign of disease activity [32,33].…”

Ultrasonographic Findings in a Large Series of Patients with Knee Pain

“…Knee effusion is mostly seen at the suprapatellar pouch in the supine position, especially at the anterior side. [15] Also, 30° flexion position of the knee is the most sensitive position for the detection of knee fluid. [16]…”