부산대학교 도서관

A hollow lumen coil for a surgical instrument is made from a continuous helically wound filament which is wound with different preload tension at different portions of the coil. When a relatively high preload tension is applied to the filament as the coil is wound, the coil will be relatively stiff. When a relatively low preload tension is applied to the filament as the coil is wound, the coil will be relatively flexible. By varying the preload tension applied to the filament while winding the coil, the coil is provided with areas of different stiffness and flexibility. The preload tension may be varied gradually or abruptly and may be varied several times along the length of the coil. Surgical instruments incorporating the coil are also disclosed. The coil is preferably made from stainless steel Type 304 wire having a diameter of approximately 0.021 inches and is wound with tensions ranging from nil to several pounds.