Fibrin clot prevents bone tunnel enlargement after ACL reconstruction with allograft

Knee Surg Sports Traumatol Arthrosc. 2017 May;25(5):1555-1560. doi: 10.1007/s00167-016-4109-y. Epub 2016 Apr 16.


Purpose: Bone tunnel enlargement is a feared complication after ACL reconstruction. The aim of this study was to evaluate whether adding a fibrin clot to the allograft for anatomic single-bundle ACL reconstruction would reduce tunnel widening.

Methods: Fifty patients who underwent anatomic single-bundle ACL reconstruction were included. Twenty-five patients received an allograft alone, and 25 patients received an allograft with fibrin clot. All patients underwent standard plain anteroposterior and lateral radiographs of the operated knee immediately after surgery and at 1-year follow-up. The size of the tunnels was measured at both time points to calculate tunnel widening. Tunnel widening at 1 year was compared between the allograft and the allograft + fibrin clot group.

Results: There was significantly less tunnel widening in the allograft + fibrin clot group for the femoral tunnel width in the middle and distal portion of the tunnel and for the tibial tunnel width in the proximal and distal portions, as compared to the allograft only group.

Conclusion: Adding a fibrin clot to the allograft in anatomic single-bundle ACL reconstruction reduces the amount of tunnel widening at 1-year follow-up. Reducing tunnel widening may positively affect outcomes after ACL surgery and may prevent inadequate bone stock during ACL revision procedures.

Level of evidence: Case-control study, Level III.

Keywords: ACL; Allograft; Fibrin clot; Radiographs; Tunnel widening.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Allografts
  • Anterior Cruciate Ligament / surgery
  • Anterior Cruciate Ligament Reconstruction / adverse effects
  • Anterior Cruciate Ligament Reconstruction / methods*
  • Case-Control Studies
  • Female
  • Femur / surgery
  • Fibrin / administration & dosage*
  • Humans
  • Male
  • Middle Aged
  • Orthopedic Procedures / methods
  • Postoperative Complications / prevention & control*
  • Retrospective Studies
  • Tibia / surgery
  • Transplantation, Homologous
  • Young Adult


  • Fibrin