Design and Kinematic Study of a Wrist External Fixator with Arthrodiatasis

• Main Authors: Chang Tien Hao, 張天豪
• Other Authors: 趙振綱
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/85341867388576962594

碩士 === 國立臺灣科技大學 === 機械工程系 === 93 === Abstract Distal radius fracture is one of the common fractures. Recently some specially designed external fixators have been widely used for the treatment of such fracture and surgically related complications. There are two kinds of wrist external fixator: non-briding fixator and briding fixator. Non-briding fixator can fix on the radius directly; there is no mechanical restriction of wrist movement with a non-bridging fixator after treatment. It has widely ROM and better reduction of distal radius fractures. But it can’t be used in the fracture with articular surfaces or comminuted fracture. Briding fixator has first insert pins to the radius and second metacarpal individually, when set fixator to the pin. Because those fixators have set across the axis of wrist, it’s usually designed as a device composed of hinge or ball joint, the main purpose of this design is in line with the axis of wrist, it can supply to the range of motion of the wrist and avoid the squeal of the wrist joint stiffness. Besides, the continuously passive motion can be done by detraction device. However, there have been some commercial wrist fixators which are often bulky and design complicated, inducing inconvenience during the rehabilitation. In this study, we firstly improved now commercial fixators and designed a new wrist fixator. Assuming a new wrist fixator and the associated radius and second metacarpal bone as a close chain system, the principle of homogeneous transformation matrix of robotics is applied in the kinematic analysis of such a chain system. Consequently, the pin placements are parameterized and their kinematic influences on the adjustability, which are in line with wrist axis of the new fixators, are analyzed. The numerical results of the current study are validated by the trigonometric model and computerized simulation. In addition, the contribution for each design parameter of external fixator was thus investigated by the Taguchi method In conclusion, the current study has designed a newly wrist external fixator. Furthermore, the new fixator is validated by the homogeneous transformation matrix and Taguchi method. The results of this study can help orthopedic surgeons take insight into the operation restraints of such a new technique. In the future, the same concept can be clinically applied to the treatment of the hinged knee and ankle joints.