Conclusions1. The viscosity of normal human knee joint fluid is greater than thatof fluid found in most pathological conditions. 2. The decreased viscosity of joint fluids found in pathologiczl ytates may be clue to one of two factors or to both. (a) dilution with extracellular water. (b) depolymerization or dissociation of a highly polymerized hyaluronic acid by hyaluronidase.