| 摘要 |
A medical instrument includes a shaft having an outer surface defining an outer diameter, a tube having an inner surface defining an inner diameter and extending over a portion of the shaft, at least one coil wound in a first rotational direction and provided between the shaft and the tube, the at least one coil having a first portion defining an inner surface interfering with an outer surface of the shaft such that the at least one coil grips the shaft, and a second portion coupled to the inner surface of the tube. The tube is movable longitudinally relative to the shaft in a first longitudinal direction when subject to force in the first longitudinal direction, and the tube is substantially immovable longitudinally relative to the shaft in a second longitudinal direction opposite the first longitudinal direction when subject to force in the second longitudinal direction only. When the tube is subject to rotational force in a second rotational direction opposite the first rotational direction, movement of the tube in the second longitudinal direction relative to the shaft is permitted. Other embodiments are also provided.
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