[Minimally invasive distraction arthrodesis of the ankle joint using threaded titanium cages]

We present the theoretical principles and the results of a new kind of minimal invasive distraction arthrodesis of the ankle joint using threaded titanium cages.

Experimental operation was done on eight cadavers using a anterio-medial and lateral approach. Threaded titanium cages (12 mm diameter), known from spine surgery, were implanted under distraction. Four operations were done without and four with radiologic control.

The samples demonstrated a high primary stability. After dissection of the ligaments a good position of the implants, with one exception, which was implanted without radiological control, was found. Cages, which were implanted under radiological control, were nearly parallel in sagittal direction, divergence ranged from 1 degree to 3 degrees (mean 2 degrees). Operation time was always shorter than 20 minutes.

As indication for using this experimental operation in patients a primary osteoarthritis with intact ligaments and without severe malposition can be regarded. From the theoretical view advantages of this technique can be seen in the minimal invasive approach, the short duration of the operation and the high primary stability.