What is the recommended placement for ACL (Anterior Cruciate Ligament) tibial tunnel?

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ACL Tibial Tunnel Placement: Anatomic Positioning for Optimal Outcomes

The optimal ACL tibial tunnel placement should be at approximately 31% from the anterior edge of the tibia for the anteromedial (AM) bundle and 50% for the posterolateral (PL) bundle in anatomic reconstruction, with the overall tibial footprint positioned close to the center of the tibia and oriented sagittally. 1

Anatomic Considerations for Tibial Tunnel Placement

Optimal Positioning

  • The tibial tunnel should be placed within the native ACL footprint to restore normal knee biomechanics
  • For single-bundle reconstruction:
    • Aim for placement between the AM and PL bundle positions (approximately 45% from the anterior margin of the tibia) 2
    • Target 47-48% from the medial tibial articular margin 2
  • For double-bundle reconstruction:
    • AM bundle: 33-34% from the anterior margin, 45-46% from the medial margin
    • PL bundle: 53% from the anterior margin, 46% from the medial margin 2

Tunnel Size Considerations

  • A minimum 9mm tibial tunnel diameter is necessary when using a transtibial technique to achieve proper femoral tunnel placement 3
  • Smaller tibial tunnel sizes (6-7mm) result in non-anatomic femoral tunnel placement with significant positioning errors (4.6mm and 2.9mm respectively) 3

Surgical Technique Impact on Tibial Tunnel Placement

Drilling Technique Comparison

  • Independent femoral (IF) drilling techniques result in more accurate tibial tunnel placement compared to transtibial (TT) techniques:

    • IF technique: 71.6% of tibial tunnel aperture contained within native footprint
    • TT technique: only 52.1% of tibial tunnel aperture within native footprint 4

  • Transtibial drilling tends to place tunnels more posteriorly:

    • 6 of 10 tunnels placed posterior to footprint center with TT technique
    • 3 of 10 tunnels placed posterior to footprint center with IF technique 4

Recommended Approaches

  • Anteromedial portal (AMP) or outside-in (OI) techniques are superior to transtibial (TT) techniques for achieving anatomic tunnel placement 5
  • OI surgical technique produces more oblique and anatomically correct femoral tunnel apertures compared to other techniques 5

Clinical Recommendations for Surgical Implementation

Preoperative Planning

  • Use CT or MRI imaging optimized for ligament evaluation to identify the native ACL footprint
  • Plan for tibial tunnel placement that will allow access to the center of the femoral footprint

Intraoperative Guidance

  1. Identify and preserve ACL tibial footprint remnants when possible
  2. Use anatomic landmarks to guide placement:
    • Position the tibial guide at the center of the native ACL footprint
    • For single-bundle reconstruction, aim between the AM and PL bundle positions
  3. Avoid common pitfalls:
    • Too anterior placement can cause graft impingement
    • Too posterior placement can compromise graft function
    • Too medial placement risks PCL impingement

Tunnel Preparation

  • Use appropriate tunnel diameter (minimum 9mm for transtibial technique) 3
  • Ensure adequate tunnel length (average tibial tunnel length of 32mm) 3
  • Consider independent drilling techniques (AMP or OI) for more accurate placement 5

Postoperative Rehabilitation Considerations

  • Begin with closed kinetic chain (CKC) exercises from week 2 postoperative 6
  • Progress to open kinetic chain (OKC) exercises from week 4 in a restricted range of motion (90-45°) 6
  • Gradually increase ROM: 90-30° in week 5,90-20° in week 6,90-10° in week 7, and full ROM in week 8 6
  • Add neuromuscular training to strength training to optimize outcomes and prevent reinjuries 6

Evaluation of Tunnel Placement

  • Postoperative CT scans can evaluate tunnel position relative to anatomic landmarks
  • Use established measurement systems (Bernard and Hertel's technique for femoral side, Staubli's technique for tibial side) 1
  • Assess percentage of tunnel aperture within native footprint and distance from tunnel center to footprint center 4

By focusing on anatomic tibial tunnel placement that respects the native ACL footprint, surgeons can optimize outcomes following ACL reconstruction, reducing the risk of graft failure and improving knee stability and function.

References

1
Research

Evaluation of the tunnel placement in the anatomical double-bundle ACL reconstruction: a cadaver study.

Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 2010

3
Research

Effect of tibial tunnel diameter on femoral tunnel placement in transtibial single bundle ACL reconstruction.

Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 2016

4
Research

Tibial tunnel placement accuracy during anterior cruciate ligament reconstruction: independent femoral versus transtibial femoral tunnel drilling techniques.

Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association, 2014

6
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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