This paper deals with solution methods of optimal synthesis of planar mechanisms. A searching procedure is defined which applies genetic algorithms based on evolutionary techniques and the type of goal function. Problems of synthesis of four-bar planar mechanisms are used to test the method, showing that solutions are accurate and valid for all cases. The possibility of extending the method to other mechanism type is outlined. The main advantages of the method are its simplicity of implementation and its fast convergence to optimal solution, with no need of deep knowledge of the searching space.
Purpose
In anterior cruciate ligament reconstruction with looped soft‐tissue grafts, an interference screw is frequently used for tibial fixation. This study compared three alternatives thought to improve the initial mechanical properties of direct bioabsorbable interference screw fixation: suturing the graft to close the loop, adding a supplementary staple, or increasing the oversize of the screw diameter relative to the bone tunnel from 1 to 2 mm.
Methods
Twenty‐eight porcine tibiae and porcine flexor digitorum profundus tendons were randomized into four testing groups: a base fixation using 10‐mm‐diameter screw with open‐looped graft, base fixation supplemented by an extracortical staple, base fixation but closing the looped graft by suturing its ends, and base fixation but using an 11‐mm screw. Graft and bone tunnel diameters were 9 mm in all specimens. Constructs were subjected to cyclic tensile load and finally pulled to failure to determine their structural properties.
Results
The main mode of failure in all groups was pull‐out of tendon strands after slippage past the screw. The sutured graft group displayed significantly lower residual displacement (mean value reduction: 47–67 %) and higher yield load (mean value increase: 38–54 %) than any alternative tested. No other statistical differences were found.
Conclusions
Suturing a soft‐tissue graft to form a closed loop enhanced the initial mechanical properties of tibial fixation with a bioabsorbable interference screw in anterior cruciate ligament reconstructions using a porcine model, and thus, this may be an efficient means to help in reducing post‐operative laxity and early clinical failure. No mechanical improvement was observed for an open‐looped tendon graft by adding an extracortical staple to supplement the screw fixation or by increasing the oversize of the screw to tunnel diameter from 1 to 2 mm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.