Histologic, biomechanical, and biological evaluation of fan-folded iliotibial band allografts for anterior cruciate ligament reconstruction

Purpose: The purpose of this study was to thoroughly characterize the fan-folded iliotibial band (FITB) allograft and compare it with anterior tibialis tendons (ATs) and native anterior cruciate ligaments (ACLs) to determine whether it measures up to those tissues. Methods: We compared the histologic structure, tensile strength to failure, creep, and stress-relaxation properties of FITBs with those of ATs and ACLs. In vitro cytotoxicity and biocompatibility of FITBs were also compared with ATs. Results: No structural difference was observed between the tissues studied. FITB ultimate tensile strength (3,459 ± 939 N) was not significantly different (P >.9999) from ultimate tensile strength of ATs (3,357 ± 111 N) and was significantly greater (P =.0005) than that of ACLs (886 ± 254 N). No significant difference (P >.9999) was observed in the increase in length resulting from creep testing between FITBs (9.5 ± 3.0 mm) and ATs (9.7 ± 4.0 mm). During stress-relaxation testing, FITBs reached 181 ± 46 N, which was not significantly different (P >.9999) from ATs (166 ± 40 N). Finally, we showed that cytotoxicity of FITBs and ATs was negligible. In vitro biocompatibility of FITBs and ATs was very good, whereas FITBs had a higher propensity to favor the attachment and infiltration of cells that proliferated for at least 4 weeks on their contact. Conclusions: We found that FITBs, ACLs, and ATs shared a similar structure made of aligned collagen fibers. No significant difference was observed between FITB and AT ultimate tensile strength, creep, and stress-relaxation viscoelastic properties. Ultimate tensile strength to failure of ACLs was lower than that of FITBs and ATs, whereas ACLs were superior to both FITBs and ATs during creep and stress-relaxation testing. FITBs and ATs showed low cytotoxicity and excellent biocompatibility in vitro, with a somewhat higher propensity of FITBs to favor cell attachment and infiltration over time. Clinical Relevance: This study suggests that FITBs have the potential to perform as well as ATs for ACL reconstruction.