The D.H.R.S.T. needle can be used to take small samples of the synovial fluid in the knee socket. This type of needle allows diagnosis and identification of particular pathologies of the knee-joint, for example, synovitis, an algetic inflammation associated whit particolar infections. The needle has a Losanga tip and a cavità on the level of the stylet which allows taking samples of the synovial fluid. The grip interlocking system allows easily introducing the needle in the socket and subsequent easy sampling of synovial tissue. This occurs by blocking the advance of the stylet through the cannula sampling and a secure closure of the cannula once the tissue has been collected.