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 or "distal surfaces" are articular, the superior generally convex, the inferior concave; the "medial" and "lateral surfaces" are also articular where they are in contact with contiguous bones, otherwise they are rough and tuberculated. The structure in all is similar: cancellous tissue enclosed in a layer of compact bone. Occasionally accessory bones are found in the carpus, but of more than 20 such described bones, only four (the central, styloid, secondary trapezoid, and secondary pisiform bones) are considered to be proven accessory bones. Sometimes the scaphoid, triquetrum, and pisiform bones are divided into two. The carpal bones are ossified endochondrally