All-Epiphyseal Anterior Cruciate Ligament Femoral Tunnel Drilling: Avoiding Injury to the Physis, Lateral Collateral Ligament, Anterolateral Ligament, and Popliteus-A 3-Dimensional Computed Tomography Study

Arthroscopy. 2018 May;34(5):1570-1578. doi: 10.1016/j.arthro.2017.12.007. Epub 2018 Feb 1.


Purpose: To investigate the relation of the at-risk structures (distal femoral physis, lateral collateral ligament, anterolateral ligament, popliteus, and articular cartilage) during all-epiphyseal femoral tunnel drilling. A second purpose was 2-fold: (1) to develop recommendations for tunnel placement and orientation that anatomically reconstruct the anterior cruciate ligament (ACL) while minimizing the risk of injury to these at-risk structures, and (2) to allow for maximal tunnel length to increase the amount of graft in the socket to facilitate healing.

Methods: Three-dimensional models of 6 skeletally immature knees (aged 7-11 years) were reconstructed from computed tomography and used to simulate all-epiphyseal femoral tunnels. Tunnels began within the ACL footprint and were directed laterally or anterolaterally, with the goal of avoiding injury to at-risk structures. The spatial relation between the ideal tunnel and these structures was evaluated. Full-length tunnels and partial length condyle sockets were simulated in the models using the same trajectories.

Results: An anterolateral tunnel could be placed to avoid direct injury to lateral structures. The safe zone on the anterolateral aspect of the femur was larger than that of a tunnel with a direct lateral trajectory (median 127 mm2 vs 83 mm2, P = .028). Anterolateral tunnels were longer than direct lateral tunnels (median 30 mm vs 24 mm, P = .041). Safe angles for anterolateral tunnels were 34° to 40° from the posterior condylar axis; direct lateral tunnels were drilled 4° to 9° from the posterior condylar axis. Sockets could be placed without direct injury to structures at risk with either orientation.

Conclusions: An all-epiphyseal ACL femoral tunnel can be placed without causing direct injury to at-risk structures. A tunnel angled anterolaterally from the ACL origin is longer and has a larger safe zone compared with the direct lateral tunnel.

Clinical relevance: The largest safe zone for femoral all-epiphyseal ACL drilling was (1) anterior to the lateral collateral ligament origin, (2) distal to the femoral physis, and (3) proximal to the popliteus tendon origin. A direct lateral tunnel may also be used, but has a smaller safe zone. Sockets or partial length tunnels may have a lower risk of injury to at-risk structures.

MeSH terms

  • Anterior Cruciate Ligament / diagnostic imaging
  • Anterior Cruciate Ligament / surgery*
  • Anterior Cruciate Ligament Injuries / diagnosis
  • Anterior Cruciate Ligament Injuries / surgery*
  • Anterior Cruciate Ligament Reconstruction / methods*
  • Cadaver
  • Child
  • Epiphyses / diagnostic imaging*
  • Epiphyses / surgery
  • Female
  • Femur / diagnostic imaging
  • Femur / surgery*
  • Humans
  • Imaging, Three-Dimensional*
  • Knee Joint / diagnostic imaging
  • Knee Joint / surgery
  • Lateral Ligament, Ankle / diagnostic imaging
  • Male
  • Tomography, X-Ray Computed / methods*