| 摘要 |
The invention concerns a bone screw having a distal end and a proximal end, which has the distinguishing features a shaft with a core diameter“k”and having an external thread with an external diameter“d”. The external diameter“d”of the thread or the core diameter“k”of the shaft tapers in a middle region of the shaft from a larger dimension“d2”or“k2”respectively towards the proximal end to a smaller dimension“d1”or“k1”, respectively, where“d1”and“k1”do not equal zero. Further, the shaft is provided with a concentrically disposed, radially expandable sleeve, and the sleeve being positioned on the part of the shaft which has the smaller external diameter“d1”. The bone screw may be introduced into a transverse borehole of a medullary pin. The medullary pin is provided with a continuous cannulation, which extends coaxially with the longitudinal axis of the medullary pin and has an external diameter DN and a wall thickness WN. The transverse borehole may have a diameter DB, which is larger than d2 as well as larger than dB-L5. In one embodiment, diameter DB may be approximately 90% of the diameter dB-L3 of the sleeve. The sleeve may be inserted completely into the transverse borehole and, with the flange, is in contact with the wall of a facet of the transverse borehole. |
