Knee Surgery, Sports Traumatology, Arthroscopy

, Volume 26, Issue 12, pp 3717–3723 | Cite as

Steeper posterior tibial slope correlates with greater tibial tunnel widening after anterior cruciate ligament reconstruction

  • Kanto Nagai
  • Yasutaka Tashiro
  • Elmar Herbst
  • Tom Gale
  • Joon Ho Wang
  • James J. Irrgang
  • William Anderst
  • Freddie H. FuEmail author



To investigate the correlation between posterior tibial slope (PTS) and tibial tunnel widening after anterior cruciate ligament reconstruction (ACL-R).


Twenty-five patients underwent anatomic single-bundle ACL-R using quadriceps tendon autograft. Six months after surgery, each patient underwent high-resolution computed tomography (CT). Tibial tunnel aperture location was evaluated using a grid method. Medial and lateral PTS (°) was measured based on a previously described method. To evaluate tibial tunnel widening, cross-sectional area (CSA) of the tibial tunnel beneath the aperture was measured using CT axial slice. Nominal elliptical area was calculated using the diameter of a dilator during the surgery and the angle between the axial slice and the tunnel axis. Percentage of tunnel widening (%) was determined by dividing the CSA by the nominal area. Pearson correlation coefficient was used to explore the association between medial/lateral PTS and tibial tunnel widening (P < 0.05).


Location of tibial tunnel aperture was 29.8 ± 6.3% in anterior–posterior direction, and 45.7 ± 2.1% in medial–lateral direction. Medial and lateral PTS were 3.7° ± 2.5° and 4.9° ± 2.4° respectively. Tibial tunnel widening was 97.2 ± 20.3%. Tibial tunnel widening was correlated with medial PTS (r = 0.558, P = 0.004) and lateral PTS (r = 0.431, P = 0.031).


Steeper medial and lateral PTS correlated with greater tibial tunnel widening. The clinical relevance is that surgeons should be aware that PTS may affect tibial tunnel widening after ACL-R. Thus, subjects with steeper PTS may need to be more carefully followed to see if there is greater tibial tunnel widening, which might be important especially in revision ACL-R.

Level of evidence



ACL Anterior cruciate ligament reconstruction Tunnel widening Cross-sectional area Posterior tibial slope Computed tomography Bony morphology Quadriceps tendon graft Tibial tunnel location 



Anterior cruciate ligament reconstruction


Posterior tibial slope


Magnetic resonance imaging






Computed tomography




Intraclass correlation coefficient


Cross-sectional area


Compliance with ethical standards

Conflict of interest

The authors declare no conflicts of interest in association with the present study.


This research was funded by NIH/NIAMS, Grant No. R01 AR 056630.

Ethical approval

The institutional review board (IRB) for human subject research in University of Pittsburgh approved all aspects of this study (ID: PRO09020493).

Informed consent

Informed consent was obtained from all patients before the enrollment.


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Copyright information

© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2018

Authors and Affiliations

  1. 1.Department of Orthopaedic SurgeryUniversity of PittsburghPittsburghUSA
  2. 2.Department of Orthopaedic SurgeryKobe University Graduate School of MedicineKobeJapan
  3. 3.Department of Orthopaedic Sports Medicine, Klinikum rechts der IsarTechnical University MunichMunichGermany

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