PATELLAR TAP / BALLOTTEMENT TEST FOR INTRA-ARTICLAR SWELLING The Patellar Tap Test is a tool to assess for intra-articular swelling of the knee joint. Being able to assess what kind of swelling you are dealing with, gives you an idea about where the lesion could be located in the knee. With extra-articular swelling (like in prepatellar bursitis or patellar tendonitis) the test will be negative. According to Kastelein et al. (2009) this test has a sensitivity of 83% and a specificity of 49% for t