Effusion Flashcards
Clinical Aspect
When we palpate the level of the medial and lateral condyles about 2 cm posterior to the medial and lateral edges of the patella, the synovium is superficial and is only covered by skin and subcutaneous fat. If there is a synovial thickening, a dense structure is felt. Swelling can be intra-articular or extra-articular.
If there is effusion associated with patellofemoral pathology, there is the possibility of moderate-to-severe patellofemoral arthrosis, severe Plical inflammation, chrondral loose bodies and osteochrondral damage.
The intraarticular swelling is often due to a synovitis and it feels soft and does not elicit a fluid wave. A clear effusion flows like a liquid, whereas blood feels like a jelly mass. Extra-articular swelling is not movable and feels like a thick, soft tissue
Patellar tap test
The patient is lying in supine with the leg extended. The physiotherapist puts pressure on the proximal side of the knee in an effort to squeeze the fluid out of the suprapatellar pouch. The fluid can be moved under the patella while maintaining the pressure on the suprapatellar pouch; the therapist uses his/her other hand to press up on the medial and lateral recesses forcing the fluid under the patella . Tapping down the patella with the index to create an upward and downward movement and a palpable ‘click’ as the patella hits the underlying femur.
If the test is negative the femur and the patella are already in contact.
A positive test is when the patella can be felt to move down through the fluid and rebounds on the patella. The test can be false positive, therefore we must always test both sides to compare.
Bulge, wipe or stroke test / Fluid displacement test
The patient in supine, with the knee in an extended position. The physiotherapist strokes upwards with the edge of the hand on the medial side of the knee to milk the fluid 10 cm proximal of the patella into the lateral compartment, and continues pushing the fluid downwards on the lateral side.
The test is positive if the physiotherapist sees fluid moving towards the medial side of the knee.
