Failed hip replacement. Axial magnetic resonance imaging (MRI) scan through a hip replacement (dark area, centre left) that has failed after less than two years. An ALVAL (aseptic lymphocytic vasculitis associated lesion) cavity (grey cloudy area) has formed in the soft tissue beneath the hip joint. The cavity is a result of excessive wear on the replacement hip components releasing metal ions that cause inflammation and tissue destruction. ALVAL reactions are most common in females, most probably due to the smaller size of their prosthesis leading to more wear. Treatment is with removal of the metal prosthesis.