Kinematic analysis with the use of 3D-CT/scan-reconstruction and covariant analysis gives the ability to have a detail kinematic prescription of the Scaphoid and Lunate bones and further of the Scapholunate joint when the wrist gets the extreme positions. This analysis can be used in the design criteria for the development of a new type screw FlexyScrew. Data obtained from the 3D-CT/scan-reconstruction and the use of covariant analysis give a detail kinematic analysis of the Scaphoid and lunate

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... bones. This data was used as the technical guidelines for constructing the FlexyScrew. Further a 3D-printed model of the Scapholunate joint which is based on the above analysis simulate the conditions in which the FlexyScrew can operate. It was verified, that insertion of the FlexyScrew in the appropriate position does not disturb the 3D joint movement between the Scaphoid and Lunate bones. Moreover the spring of the Flexyscrew allows the relative motion, translation and rotation, of Scaphoid and Lunate bones and generally can follow in a satisfactory way the movements of the joint. The insertion of the FlexyScrew seems to offer a good alternative method for the difficult and problematic carpal Scapholunate surgeries. This simple kinesiological method of analysis with the appropriate flexible screw can be applied also to other unstable joints, caused by ligamentous injuries, for example replacing the torn Anterior Cruciate Ligament in the knee joint.