Palpation of the proximal interphalangeal (PIP) joint

The examiner places two fingers of one hand on the lateral joint lines and two fingers from the opposite hand on the top and bottom of the joint. Pressure is applied from the top and bottom while simultaneously feeling for the distensibility of synovial thickening, excessive joint fluid, or both. The maneuver can be enhanced by alternating the pressure from one set of fingers to the other. The synovial lining of the small joints extends 5 to 6 mm above and below the joint line. An excessive amount of fluid causes the characteristic fusiform shape.