A balloon for use in compressing cancellous bone and marrow (also known as medullary bone or trabecular bone). The balloon comprises an inflatable balloon body for insertion into said bone. The body has a shape and size to compress at least a portion of the cancellous bone to form a cavity in the cancellous bone and/or to restore the original position of the outer cortical bone, if fractured or collapsed. The balloon desirably incorporates restraints which inhibit the balloon from applying excessive pressure to various regions of the cortical bone. The wall or walls of the balloon are such that proper inflation of the balloon body is achieved to provide for optimum compression of the bone marrow. The balloon can be inserted quickly into a bone. The balloon can be made to have a suction catheter. The balloon can be used to form and/or enlarge a cavity or passage in a bone, especially in, but not limited to, vertebral bodies. Various additional embodiments facilitate directionally biasing the inflation of the balloon.