objective To evaluate the biomechanical characteristics of Ni-ti barb wrist prosthesis.

Six cases of normal human fresh forearm were collected (provided by department of anatomy, Southern Medical University). Inclusion criteria: fresh frozen adult forearm; the wrists were free to move. Exclusion criteria: fracture, joint dislocation or bone tumor on the adult forears. In the Cortex motion capture system, the range of motion (ROM) of wrist prosthesis was compared in flexion, extension, ulnar deviation, and radial deviation before and after total wrist arthroplasty (TWA). The data were analysed by paired t test. In the Elector Force high precision biological material test system, the prostheses were loaded with an increasing pull-out force 2 N per second, until the prosthesis displacement was more than 2 mm. The prosthesis loosening pull-out force at the moment was recorded. Independent sample t test was used to compare the pull-out force of the radial component and wrist component .

ROM of wrist prosthesis in extension, ulnar deviation, and radial deviation showed no statistical difference (P>0.05) before and after TWA. For preoperative maximum flexion was (75.0±3.5) °, postoperative maximum flexion was (52.6±3.2) °, which showed significant difference (t=14.69, P<0.05). The pull-out force of radius prosthesis was (164±15) N, and the pull-out force of metacarpal prosthesis was (512±38) N, which was statistically different( t=-20.859, P< 0.05) .

Ni-ti barb wrist prosthesis can basically meet ROM and pull-out resistance of the daily biomechanics demands, which has some potential value of clinical application.