Introduction and Background: There are an estimated 200,000 anterior cruciate ligament (ACL) ruptures yearly in the USA. Pretensioning allografts prior to anterior cruciate ligament reconstruction in order to minimize graft laxity is a common, but controversial practice.

The goal of this study is to determine if pretensioning anterior tibialis (ATs) and fan-folded iliotibial bands (FITBs) alters their creep and stress relaxation properties.

Materials and Methods: One of each matched pair of allografts was pretensioned under a load of 67 N (15 lbs) for 15 minutes. Each group (pretensioned and non-pretensioned) was then mounted in the tensile grips of the MTS machine. Creep was performed by loading in load control to 67 N for 30 seconds to mimic the load applied by the surgeon at the time of graft fixation onto the patient’s tibia. Stress relaxation testing was then performed to mimic the behavior of the graft early post-implantation. The grafts were cyclically extended (+1.5 mm) for 10 minutes at 1 Hz.

Results: We observed that pretensioned FITBs crept more than their non-pretensioned counterparts (3.5 mm additional creep, p =0.02). The increase in creep observed after pretensioning was not significant for the ATs. Pretensioned and non-pretensioned allografts, either ATs or FITBs, did not exhibit any significant difference during the stress relaxation test, which was designed to mimic the post-implantation graft behavior.

Discussion and Conclusions: Under these study parameters, pretensioning of ATs and FITBs appeared to have no obvious mechanical advantage, thereby questioning the utility of the clinical practice. Additional research will be needed to refine these findings as well as to understand the molecular basis for the observed graft behavior after pretensioning.