Diagnostic instrument

An instrument for measurement of the deformation resistance of cartilaginous tissue, such as the articular surface of the cartilage of the patella comprising, in combination, a cannula having a bore, said cannula having a first end portion defining a blunt stop surface, a carrier member movably mounted in said bore and including a sensing end portion and a manipulation end portion, complemental limit stop means formed on said cannula and carrier member positioned to engage at a limiting inserted position of said sensing end portion of said carrier member into said cannula and to block further relative movements of said parts in the direction of insertion of said carrier member, a pressure sensing transducer mounted in said carrier member adjacent said sensing end portion, said transducer including a pressure sensing surface at a lead portion thereof, said pressure sensing surface, at said limiting inserted position of said carrier member being disposed within said cannula in proximate spaced relation to said stop surface, and a resilient, compressible pressure transmission member mounted on said pressure sensing surface of said transducer, said transmission member, in said limiting inserted position, projecting a predetermined distance beyond said stop surface.