Balloon catheter for compressing spongy bone material, said balloon catheter comprising - an elongated flexible catheter body having a proximal end and a distal end, a longitudinal axis extending between the proximal end and the distal end, and a distal end portion and a proximal end portion; - a connecting element which is firmly connected to the proximal end portion of the catheter body and which has at least two or more further connecting ports (19, 20); - a first inflatable and deflatable balloon member inflatable to a first diameter to an inflated state, and which is arranged coaxially around the catheter body at its distal end, and wherein the first balloon member is inflatable via a first lumen via a fluid conducted therein, the first lumen extending from the distal end portion along the longitudinal axis of the catheter body and to the proximal end into a first connecting port, the first lumen having an opening opening into the interior of the first balloon member; and further wherein the first balloon member has a first distal balloon portion, a first proximal balloon portion and a first central balloon portion therebetween, the first balloon member being fixed to the catheter body via the first distal balloon portion and the first proximal balloon portion, and wherein the first balloon element has a first constriction in the first central balloon portion which reduces the balloon element circumference in the inflated state in comparison with the portions of the central balloon portion lying immediately to the right and left of the constriction; - a second inflatable and deflatable balloon member inflatable to a second diameter to an inflated state, said second balloon member being arranged coaxially around the catheter body immediately adjacent and proximal to the first balloon member, and said second balloon member being inflatable via a second lumen via a fluid carried therein, the second lumen extending from the distal end portion along the longitudinal axis of the catheter body and to the proximal end into a second connecting port, the second lumen having an opening opening into the interior of the second balloon member; and further wherein the second balloon member has a second distal balloon portion, a second proximal balloon portion and a second central balloon portion therebetween, the second balloon member being fixed to the catheter body via the second distal balloon portion and second proximal balloon portion, and wherein the second balloon element has a first constriction in the second central balloon portion, which reduces the balloon element circumference in the inflated state in comparison with the portions immediately to the right and left of the constriction, wherein the first proximal balloon portion of the first balloon element and the second distal balloon portion of the second balloon element directly and flush with each other, or overlap or are configured in one piece. - an elongated flexible catheter body having a proximal end and a distal end, a longitudinal axis extending between the proximal end and the distal end, and a distal end portion and a proximal end portion; - a connecting element which is firmly connected to the proximal end portion of the catheter body and which has at least two or more further connecting ports (19, 20); - a first inflatable and deflatable balloon member inflatable to a first diameter to an inflated state, and which is arranged coaxially around the catheter body at its distal end, and wherein the first balloon member is inflatable via a first lumen via a fluid conducted therein, the first lumen extending from the distal end portion along the longitudinal axis of the catheter body and to the proximal end into a first connecting port, the first lumen having an opening opening into the interior of the first balloon member; and further wherein the first balloon member has a first distal balloon portion, a first proximal balloon portion and a first central balloon portion therebetween, the first balloon member being fixed to the catheter body via the first distal balloon portion and the first proximal balloon portion, and wherein the first balloon element has a first constriction in the first central balloon portion which reduces the balloon element circumference in the inflated state in comparison with the portions of the central balloon portion lying immediately to the right and left of the constriction; - a second inflatable and deflatable balloon member inflatable to a second diameter to an inflated state, said second balloon member being arranged coaxially around the catheter body immediately adjacent and proximal to the first balloon member, and said second balloon member being inflatable via a second lumen via a fluid carried therein, the second lumen extending from the distal end portion along the longitudinal axis of the catheter body and to the proximal end into a second connecting port, the second lumen having an opening opening into the interior of the second balloon member; and further wherein the second balloon member has a second distal balloon portion, a second proximal balloon portion and a second central balloon portion therebetween, the second balloon member being fixed to the catheter body via the second distal balloon portion and second proximal balloon portion, and wherein the second balloon element has a first constriction in the second central balloon portion, which reduces the balloon element circumference in the inflated state in comparison with the portions immediately to the right and left of the constriction,