Frontman Vince Neil recently said one of the reasons Crue were aiming to bow out after one more album, a world tour and a movie was that Mars was too ill to deal with the trauma of constant travel.

The guitarist said that wasn't true � but now drummer Tommy Lee has repeated the suggestion, telling Dedmau5: "Mick has a spinal disease that's slowly fusing his vertebrae together. It's treatable but not curable. It's progressively getting worse and it's painful for him, so he doesn't want to tour much longer."