Using a sharp knife cut off some of the important fat layer from the outside of the lamb leg. Sprint the knife around the curved hipbone that protrudes from the sirloin end of the lamb leg. Cut close to the bone to free the bone from the meat and connective tissues attached to it, which will permit the bone to be dragged out. On the shank end of the lamb leg, run the knife around the shank bone to release the meat and tendons from the bone. Bend and drag the bone from the flesh. Follow the same procedure for removal of the upper lamb leg bone in the sirloin end. Put in a knife into the cavity created by the removal of the hipbone and cut closely around the upper lamb leg bone. When the meat and connective tissue are complimentary from the bone, the bone can be removed from the flesh of the upper lamb leg. A lamb leg that has been de boned is often cut in half to separate the sirloin and shank ends of the leg. The halves can be rolled and attached and sold as dense roasts.