The femoral posterior fan-like extension of the ACL insertion increases the failure load

  • Soheil Sabzevari
  • Humza Shaikh
  • Brandon Marshall
  • Junjun Zhu
  • Monica A. Linde
  • Patrick Smolinski
  • Freddie H. FuEmail author



To examine the role of the posterior fan-like extension of the ACL’s femoral footprint on the ACL failure load.


Sixteen (n = 16) fresh frozen, mature porcine knees were used in this study and randomized into two groups (n = 8): intact femoral ACL insertion (ACL intact group) and cut posterior fan-like extension of the ACL (ACL cut group). In the ACL cut group, flexing the knees to 90°, created a folded border between the posterior fan-like extension and the midsubstance insertion of the femoral ACL footprint and the posterior fan-like extension was dissected and both areas were measured. Specimens were placed in a testing machine at 30° of flexion and subjected to anterior tibial loading (60 mm/min) until ACL failure.


The intact ACL group had a femoral insertion area of 182.1 ± 17.1 mm2. In the ACL cut group, the midsubstance insertion area was 113.3 ± 16.6 mm2, and the cut posterior fan-like extension portion area was 67.1 ± 8.3 mm2. The failure load of the ACL intact group was 3599 ± 457 N and was significantly higher (p < 0.001) than the failure load of the ACL cut group 392 ± 83 N.


Transection of the posterior fan-like extension of the ACL femoral footprint has a significant effect on the failure load of the ligament during anterior loading at full extension. Regarding clinical relevance, this study suggests the importance of the posterior fan-like extension of the ACL footprint which potentially may be retained with remnant preservation during ACL reconstruction. Femoral insertion remnant preservation may allow incorporation of the fan-like structure into the graft increasing graft strength.


ACL Midsubstance Posterior fan-like extension Femoral footprint Failure load Morphology 



This study was funded by the Department of Orthopaedic Surgery at the University of Pittsburgh.

Compliance with ethical standards

Conflict of interest

Authors have no conflicts to disclose.

Ethical approval

No ethical approval was required from IACUC.

Informed consent

Not applicable to this study.


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Copyright information

© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2019

Authors and Affiliations

  1. 1.Department of Orthopaedic SurgeryUniversity of Pittsburgh Medical CenterPittsburghUSA
  2. 2.Department of Orthopaedic SurgeryRazavi Hospital, Imam Reza International UniversityMeshhadIran
  3. 3.Deptartment of Mechanical Engineering and Materials ScienceUniversity of PittsburghPittsburghUSA

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