June 21, 2011 The MedUni Vienna's University Department of Trauma Surgery at Vienna General Hospital is developing new treatments for traumatic bone defects caused by accidents. A severely shortened thighbone as the result of an accident has now been extended by using the innovative nail after lengthening (NAL) method, creating an increase of 26 centimetres in only eight months.
Broken and severely damaged bones are the frequent and well-known consequence of an accident. A less well-known bone defect which can result following an accident is the shortening of the long bones (for example the thighbone or the shinbone). The so-called callus distraction (bone extension) is an effective and safe treatment in these cases. This entails the bone being divided before an artificial growth cartilage is inserted. With the controlled enlargement of this growth cartilage, the bone can be extended, even in adults. A ring-shaped external frame (external fixator) is used for the expansion, which is attached to the divided bone and gradually moves apart.
Conventional callus distraction: one centimetre of bone extension per month
After extension the bone still has to set. During conventional callus distraction the external frame remains attached to the affected limb for this to take place. Prof. Dr. Gerald E. Wozasek from MedUni Vienna's University Department of Trauma Surgery at Vienna General Hospital adds: "In the ideal case the bone can be extended by one millimetre per day. A further two days per millimetre are necessary for the bone to set. The rule of thumb is that this corresponds in conventional callus distraction to one centimetre of bone extension per month of the wearing of the external frame. Especially for large expansions, the callus distraction can therefore be time-consuming and uncomfortable. There is also a general risk of infection as the insertion points of the external frame being used are contaminated with bacteria."
As an alternative there is the innovative NAL method (NAL / Nailing after Lengthening). Wozasek has already been able to successfully implement this method on several occasions in which following the end of bone expansion, the external system (external frame) is changed to an internal stabilisation system (intramedullary nail). The greatest advantage is in the time saved as the patient only has to wear the cumbersome, bulky external frame for one third as long as otherwise, as the bone can be exerted fully and immediately after the implementation of a stabilising intramedullary nail.
26 centimetres of severely damaged thighbone
The largest callus distraction using the NAL method to date has recently been successfully concluded by Wozasek. In July 2010 a 15-year-old called Patrick severely injured his left thigh. The thighbone was severed over a length of 26 centimetres above the knee and a large piece of the thigh has been removed. The leg was still attached only by a few muscles, nerves and an artery. The knee joint was completely destroyed. The popliteal vein was also severed and the tissue severely contaminated.
Urgent measures to stabilise the severely damaged thigh
The accident victim was taken on by Wozasek at MedUni Vienna's University Department of Trauma Surgery at the Vienna General Hospital. "The wound looked as if the bone had been torn out. During my 30 years of work as a trauma surgeon I had never seen anything like this." In order to stabilise the injured leg, and following suturing of the injured vein by Wozasek, an external frame was mounted, the leg shortened and at this point a construction composed of intramedullary wires and bone cement as a placeholder was implemented. The success of the measures was quickly seen.
Amputation or bone extension? During this time Wozasek discussed with Patrick and his parents the possibility of amputation. "As the knee had been destroyed, Patrick had to be clear that his leg would remain stiff. After an amputation he would have been able to go home within three weeks." This was no option for the young man from Lower Austria. He immediately wanted the alternative of callus distraction as offered by Wozasek. 26 centimetres of bone should be reconstructed, and this was an extraordinary undertaking not only due to the length but also due to the severe thigh injury. Wozasek adds: "Patrick took this decision even though he knew that he would have several difficult years ahead of him as a result." At the beginning of September 2010 reconstruction began at the General Hospital. This entailed Wozasek sawing up the bone into two areas and implementing an external frame. Then the extension of Patrick's thighbone and shinbones started.
Eight months later: the bone has been extended by 26 centimetres and can bear full weight
This was achieved by May 2011. Patrick's bone had been extended by 26 centimetres in only eight months through callus distraction. To set the bone he would have now had to wear the bulky frame for almost another two years. Wozasek could spare the now 16-year-old Patrick from this through the NAL method. A few days ago Wozasek removed the external frame in a four-hour operation. The great challenge was the implementation of an 80-centimetre long intramedullary nail, which connects the shinbone with the thighbone and thereby supports the leg. Wozasek said shortly after the operation: "Patrick shall soon be fully mobile again. He even thanked me for the operation whilst he was still in the post-anesthesia recovery room. That was the nicest moment for me."
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