Experimental shortening of the radius in the treatment of Kienböck's disease.

Aim: The aim of the research was to determine the smallest amount of loading on the lunate bone obtained by gradually shortening the radius in different ulnar variants as the potential treatment of Kienböck's disease.

Methods: The research was conducted on anatomic preparations of 20 upper extremities using only the distal part of the forearm and hand, placing them in exactly defined positions. A Fuji Prescale film was inserted in the open radiocarpal joint to measure pressure after compressing axially by changing the length of forearm in four stages by the gradual shortening of the radius.

Results: The greatest reduction of average pressure on the lunatum achieved by shortening the radius depended on ulnar variant. In ulnar variant 0, the greatest reduction of average pressure on lunatum was achieved by shortening the radius for 3 mm (24% reduction). For ulnar variant -1, the greatest reduction of average pressure on lunatum was achieved by shortening the radius for 2 mm (37% reduction). For ulnar variants -2, -3 and +1, the greatest reduction of average pressure on lunatum was achieved by shortening the radius for 3 mm (5%, 75% and 9% respectively).

Conclusions: The pressure distribution in the distal radiocarpal joint is vital for healing, and shortening of the radius relieves the pressure on the lunate bone. The exact type of surgery and the amount of radial osteotomy depends on preoperative ulnar variant.