The advanced practice registered nurse (APRN) assesses the knee of a patient who presents with swelling of their right knee. The APRN places their thumb and index finger of their right hand on each side of the patella; with the left hand the APRN compresses the suprapatellar recess against the femur (as shown in the figure below). The APRN is able to palpate ejected fluid or "ballooning" of fluid. The APRN documents a positive "balloon sign", which is associated with:

Knee joint swelling assessment helps determine the presence and severity of intra-articular fluid accumulation. The “balloon sign” (bulge sign) is a clinical maneuver used to detect effusion in the suprapatellar pouch by shifting synovial fluid within the joint space. The amount of fluid displaced and palpated helps distinguish between minor and significant joint effusions. A clearly palpable fluid wave or ballooning suggests a larger volume of intra-articular fluid. Rationale: A. Bursitis is inflammation of a bursa, typically presenting as localized swelling, warmth, and tenderness over a specific area such as the prepatellar or infrapatellar region. It does not involve free fluid within the joint space and therefore does not produce a positive balloon sign. The maneuver described assesses intra-articular effusion rather than bursal inflammation. B. Minor effusion may cause subtle swelling and may produce a weak or barely detectable bulge sign, but not a clearly palpable fluid wave or ballooning effect. In minor fluid accumulation, the amount of synovial fluid is insufficient to create a strong displacement response. Therefore, a definitive balloon sign indicates more than a minimal effusion. C. Rheumatoid arthritis is a chronic inflammatory joint disease that can lead to joint effusions, but it is not defined by the presence of a balloon sign. While RA may cause synovitis and swelling, the test result reflects the quantity of fluid rather than the underlying etiology. The balloon sign alone does not specifically indicate rheumatoid arthritis. D. Major knee effusion is correctly indicated by a positive balloon (bulge) sign with palpable fluid displacement. This finding suggests a significant accumulation of synovial fluid within the joint capsule, enough to be shifted and felt during examination. It is commonly associated with trauma, inflammatory arthritis, or infection, but the sign specifically reflects large-volume intra-articular fluid.Top of FormBottom of Form