A minimal invasive distraction arthrodesis of the ankle joint using threaded titanium cages

Objective: We present the theoretical principles and the results of a new k ind of minimal invasive distraction arthrodesis of the ankle joint using th readed titanium cages. Method: Experimental operation was done on eight cadavers using a anterio-m edial 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. Results: The samples demonstrated a high primary stability. After dissectio n of the ligaments a good position of the implants, with one exception, whi ch was implanted without radiological control, was found. Cages, which were implanted under radiological control, were nearly parallel in sagittal dir ection, divergence ranged from 1 degrees to 3 degrees (mean 2 degrees). Ope ration time was always shorter than 20 minutes. Conclusion: As indication for using this experimental operation in patients a primary osteoarthritis with intact ligaments and without severe malposit ion can be regarded. From the theoretical view advantages of this technique can be seen in the minimal invasive approach, the short duration of the op eration and the high primary stability.