Kienböck's disease a tendency of the implant to smooth the edges of the surrounding bones, thus causing painful pinched nerves when the bones slip out of place. After the lunate is removed, another procedure, "ulnar shortening" can be performed. This relieves pressure on the newly formed wrist joint of the pisiform, hamate and capitate. Depending on the surgeon, the procedure may be performed the same way as the "radial shortening" where a small section is removed, or the entire top of the ulna may be excised. At Stage 4, the lunate has completely disintegrated and the other bones in the wrist have
Carpal bones with a total range of 170 degrees. During radial abduction the scaphoid is tilted towards the palmar side which allows the trapezium and trapezoid to approach the radius. Because the trapezoid is rigidly attached to the second metacarpal bone to which also the flexor carpi radialis and extensor carpi radialis are attached, radial abduction effectively pulls this combined structure towards the radius. During radial abduction the pisiform traverses the greatest path of all carpal bones. Radial abduction is produced by (in order of importance) extensor carpi radialis longus, abductor pollicis longus, extensor pollicis longus, flexor carpi radialis, and flexor pollicis