Five Surgical Techniques For Carpal Collapse: A Biomechanical Comparison

Objective To investigate the biomechanical changes after different operations for carpal collapse. Methods On six fresh cadaver adult specimens of wrist were simulated five different operations for carpal collapse. The pressure sensitive films were inserted into the wrists and loaded on the material testing system. The same testing procedure were repeated under every functional motion (the neutral position, flexion 5?, extension 30?, radial deviation 10?, ulnar deviation 15 0 ). The information on the films was studied. Results Under the neutral position, the average wrist pressure intensity was 22.9?.3 N/cm2. The value had no statistical changes after the excision of the distal segment of the scaphoid and arthrodesis of the proximal segment, the capitate and the lunate, after scaphoid excision with capitolunate artrodesis and after four-corner arthrodesis with scaphoid excision. The value of the capitolunate fusion with scaphoid and triquetrum excision and of proximal row carpectomy were 103. 2 + 37. 2N/cm2 and 136. 4 ?0. 7N/cm2 respectively. Under the five wrist positions within functional range, the 30?extension postion of all the limited wrist arthrodesis had the highest pressure intensity. In proximal row carpectomy, it was found in the neutral position. Conclusions Under neutral position, the pressure distribution of normal wrists was extremely even. There were no obvious biomechanical changes after excision of the distal segment of scaphoid with arthrodesis of the proximal segment, the capitate and the lunate and after scaphoid excision with capitolunate arthrodesis. The general wrist pressure intensity of the four-corner arthrodesis was higher. The highest general wrist pressure intensity was found in the groups of proximal row carpectomy and capitoulunate arthrodesis with scaphoid and triquetrum excision. The pseudo radiocapitate joint after proximal row carpectomy boasted certain abnormal biomechanics.