The Locking Cage is utilised for clinical cases with severe acetabulum deficiency, to reconstruct the acetabular structure before the joint prosthesis is mounted on. The Locking cage consists of a locking cage main body (diameters in 50~70 mm) and required bone screws (lengths in 15~75 mm) for basic fixation. The hook (3 sizes) and ischial flange (1 size) are modular designs for optional use when demand for extra stability exists. The auto break-off locking nut is the key item to complete the locking mechanism, converting the bone screws from its original compressive function to a locking type function.