A device for endoscopically delivering at least one therapeutic substance into a small articular cavity, said device comprising: - a cannula defining at least one extrusion channel and comprising: - a proximal portion; - a flexible distal portion having an extrusion mouth and - a substantially rigid intermediate portion between said flexible distal portion and said proximal portion, wherein said proximal portion is configured to feed and push a therapeutic substance into said extrusion channel, so that said therapeutic substance can pass through said extrusion channel flowing through said intermediate portion and through said flexible distal portion, and can then exit from said extrusion mouth, further comprising: - at least one actuation cable (50,50',50") having: - a proximal end operable at said proximal portion of said cannula; - a distal end connected to said flexible distal portion of said cannula at said extrusion mouth, and configured to pull said flexible distal portion with a force transversal to said extrusion channel, bringing said flexible distal portion from an undeformed conformation to a deformed conformation (B,B',B") characterized in that said substantially rigid intermediate portion (17,57) has a distal rigid edge from which said flexible distal portion protrudes, and wherein said distal rigid edge has a passageway exit of a passageway for said actuation cable (50,50',50"), said distal rigid edge and said passageway exit of said passageway arranged in such a way that only said flexible distal portion of said cannula can be brought, by said actuation cable (50,50',50"), from said undeformed conformation to said deformed conformation (B,B',B"), in order to reach said small articular cavity, while said intermediate portion is always undeformed. - a cannula defining at least one extrusion channel and comprising: - a proximal portion; - a flexible distal portion having an extrusion mouth and - a substantially rigid intermediate portion between said flexible distal portion and said proximal portion, - a proximal portion; - a flexible distal portion having an extrusion mouth and - a substantially rigid intermediate portion between said flexible distal portion and said proximal portion, wherein said proximal portion is configured to feed and push a therapeutic substance into said extrusion channel, so that said therapeutic substance can pass through said extrusion channel flowing through said intermediate portion and through said flexible distal portion, and can then exit from said extrusion mouth, further comprising: - at least one actuation cable (50,50',50") having: - a proximal end operable at said proximal portion of said cannula; - a distal end connected to said flexible distal portion of said cannula at said extrusion mouth, and configured to pull said flexible distal portion with a force transversal to said extrusion channel, bringing said flexible distal portion from an undeformed conformation to a deformed conformation (B,B',B") - at least one actuation cable (50,50',50") having: - a proximal end operable at said proximal portion of said cannula; - a distal end connected to said flexible distal portion of said cannula at said extrusion mouth, and configured to pull said flexible distal portion with a force transversal to said extrusion channel, bringing said flexible distal portion from an undeformed conformation to a deformed conformation (B,B',B") - a proximal end operable at said proximal portion of said cannula; - a distal end connected to said flexible distal portion of said cannula at said extrusion mouth, and configured to pull said flexible distal portion with a force transversal to said extrusion channel, bringing said flexible distal portion from an undeformed conformation to a deformed conformation (B,B',B") characterized in that said substantially rigid intermediate portion (17,57) has a distal rigid edge from which said flexible distal portion protrudes, and wherein said distal rigid edge has a passageway exit of a passageway for said actuation cable (50,50',50"), said distal rigid edge and said passageway exit of said passageway arranged in such a way that only said flexible distal portion of said cannula can be brought, by said actuation cable (50,50',50"), from said undeformed conformation to said deformed conformation (B,B',B"), in order to reach said small articular cavity, while said intermediate portion is always undeformed.