Does non-contact or delayed contact of an adjustable-loop femoral button affect knee stability following anterior cruciate ligament reconstruction?

Background: The purpose of this study was to investigate whether cortical non-contact or delayed contact of an adjustable-loop button for femoral fixation could affect knee stability following anterior cruciate ligament (ACL) reconstruction. Methods: Eighty subjects who underwent single-bundle ACL reconstruction using an adjustable-loop femoral cortical button were retrospectively reviewed regarding patient demographics, graft size, combined surgery, and postoperative 2-year results of knee stability, functional scores, and radiographic tunnel widening. We compared the contact and the non-contact groups determined by position of the button observed in immediate postoperative radiographs. According to 2-year postoperative radiographs, the non-contact group was further divided into two subgroups (delayed contact and persisting non-contact subgroups) and results were compared. Results: The contact group had 46 patients and the non-contact group had 34 patients. The average gap distance in the non-contact group was 1.9 ± 0.6 (1.1–3.4) mm. There were no significant differences in KT-1000 arthrometric knee stability (p =.667) or Lysholm score (p =.198), or International Knee Documentation Committee (IKDC) score (p =.091) between the two groups. No significant differences in tunnel widening were found at femoral and tibial tunnels on anteroposterior and lateral radiographs (p >.1, all tunnels). In addition, delayed contact subgroup and persisting non-contact subgroup showed similar radiographic and clinical outcomes. Conclusion: Surgeons should strive to obtain cortical contact of the adjustable-loop femoral button. Nevertheless, cortical non-contact with less than 3 mm of gap distance did not affect knee stability, radiographic outcomes, or clinical outcomes. Level of evidence: Level III, retrospective comparative study.