Load shaping for dynamic tensioning mechanisms and methods
A surgical tensioning device for dynamically holding two tissue portions in contact with one another comprises a resilient body having a plurality of spring elements, and a plurality of stop members for limiting travel of the spring elements in order to control energy stored or delivered by the spring elements. A length of suture is also provided, wherein a first end of the suture is connected to the resilient body at a first attachment point and a second end of the suture is connected to the resilient body at a second attachment point. In one embodiment, the stop members contact one another to limit compression of the spring elements. When the suture is placed in tension, the spring elements move to an extended configuration and the stop members move apart, creating gaps between ends of each of the stop members. When the gaps become sufficiently large, edges of the stop elements contact corresponding spring elements to impede further widening of the gaps and consequent further extension of the spring elements, thus protecting the springs.
1. A method for securing together two spaced bodily tissues using a cerclage procedure, comprising:
wrapping a length of suture about the tissue to be secured together, wherein first and second ends of the suture are connected to attachment points on a resilient body; and
limiting the extension of a spring element in the resilient body as the tissues begin to heal and tension is applied, as a result of the healing process, to the suture ends;
wherein the limiting step is performed by engaging a stop against the spring element after a predetermined extension travel of the spring element.
2. The method as recited in claim 1 , wherein the stop comprises a relatively rigid member which engages the spring element to inhibit further extension thereof.
3. The method as recited in claim 1 , wherein the stop comprises a strap which attains its full length when the spring element has traveled the predetermined extension distance, thereby preventing further extension of the spring element.
4. The method as recited in claim 1 , and further comprising a step of pre-compressing the resilient body to apply tension to the suture ends, so that the tissue portions to be secured together are compressed together.
5. The method as recited in claim 4 , and further comprising a step of limiting the compression travel of the resilient body to avoid tissue strangulation.