Optimization of Insertion Holes and Anchor Design for Cylinder Shaped Toggle Type Suture Anchors
Master of Science (MS)
Semester of Degree Completion
This research was performed to optimize insertion holes and anchor design for cylinder shaped toggle type suture anchors. Four types of anchors were investigated in terms of pull strength and design in acrylic plate and pig bone. They included small type A and B anchors and large type A and B anchors.
Pull strength trends suggest that the small type anchors behave similarly since their external dimensions are identical, with the exception of type A anchor having a hole running from one end of the cylinder to the other like a pipe. It was found that the suture would fail primarily at the anchor for both small anchors. SEM analysis provided a clear image of what was occurring to the suture/anchor in tension. The 0.889 mm suture hole in the anchor did not allow enough clearance for the USP #2 suture under applied load. As a result, the anchor design limits the anchor from achieving a maximum strength.
Based upon the observations on implementation, an insertion hole diameter between 2.3 and 2.4 mm would be desirable for the small anchors. Nonetheless, the 2.4 mm hole diameter was close to the 2.5 mm hole in which all tests failed upon toggle. It was recommended that a hole size of 2.3 mm be used because of easy implementation, consistently high pull strengths and relatively low standard deviations in pull strength testing.
Large anchor type A and B showed a different pull strength trend. Large anchor A demonstrated characteristics similar to the smaller anchors. The suture/anchor system failed due to suture fracture near the hole of the anchor. It was noticed that the small type anchors and large type A anchor had the same suture hole diameters of 0.889 mm, which limited the suture to reach its potential strength.
Large anchor type B failed predominantly at the knot. It demonstrated a pull strength and standard deviation closer to that of USP #2 suture. The suture hole diameter of 1.17 mm shifted the failure point away from the anchor to the knot. Given the observations on implementation and pull strength, it was recommended that an insertion hole of 3.3 mm be used because of its impressive pull strength and relatively low standard deviation.
Fedenia, Adam, "Optimization of Insertion Holes and Anchor Design for Cylinder Shaped Toggle Type Suture Anchors" (1999). Masters Theses. 1690.