The blocking hook is part of a prosthesis system. The blocking plate and blocking hook are assembled together in the knee joint as a unit.
They are used to prevent accidental variable knee flexion as a protection of the knee joint. In this case the blocking hook, which is rotatable, snaps in on the blocking plate in the extended position and blocks the flexion of the prosthesis.
When the blocking hook is lifted in the extended position of the prosthesis from a lifting device, the flexion of the knee prosthesis is activated and the patient can sit down, for example.