An in vitro analysis of wrist motion: the effect of limited intercarpal arthrodesis and the contributions of the radiocarpal and midcarpal joints.

Radiocarpal and intercarpal arthrodeses were simulated in 12 fresh cadaver wrists by means of external fixation. Range-of-motion measurements were made before and after simulated arthrodesis and used to calculate the contribution of the midcarpal and radiocarpal joints to wrist motion, as well as the residual wrist motion after limited intercarpal arthrodeses. Relative contributions to wrist motion were as follows: wrist flexion: radiocarpal (RC) joint 63%, midcarpal (MC) joint 36%; wrist extension: RC joint 53%, MC joint 46%. The wrist motion remaining after simulated arthrodeses was as follows: capitate-hamate: flexion (Flx) 98%, extension (Ext) 92%, ulnar deviation (UD) 96%, radial deviation (RD) 90%; scaphoid-lunate: Flx 97%, Ext 91%, UD 90%, RD 91%; scaphoid-trapezium-trapezoid: Flx 86%, Ext 88%, UD 67%, RD 69%; scaphoid-lunate-triquetrum: Flx 91%, Ext 82%, UD 86%, RD 70%; capitate-lunate: Flx 70%, Ext 59%, UD 89%, RD 79%; capitate-hamate-triquetrum: Flx 88%, Ext 79%, UD 88%, RD 81%; hamate-triquetrum: Flx 90%, Ext 85%, UD 89%, RD 94%; scaphoid-trapezium-trapezoid-capitate: Flx 85%, Ext 77%, UD 64%, RD 57%.