Surgically oriented measurements for three-dimensional characterization of tunnel placement in anterior cruciate ligament reconstruction.
OBJECTIVE
To develop and evaluate the feasibility and reliability of an alternative three-dimensional (3D) measurement system capable of characterizing tunnel position and orientation in ACL reconstructed knees.


METHODS
We developed a surgically oriented 3D measurement system for characterizing femoral and tibial drill tunnels from ACL reconstructions. This is accomplished by simulating the positioning of the drill bit originally used to create the tunnels within the bone, which allows for angular and spatial descriptions along defined axes that are established with respect to previously described anatomic landmarks and radiographic views. Computer-generated digital phantoms composed of simplified geometries were used to verify proper calculation of angular and spatial measurements. We also evaluated the inter-observer reliability of the measurements using 10 surfaces generated from cadaveric knees in which ACL tunnels were drilled. The reliability of the measurements was evaluated by intraclass correlation coefficients.


RESULTS
The digital phantom evaluation verified the measurement methods by computing angular and spatial values that matched the known values in all cases. The intraclass correlation coefficient was calculated for four users and was found to range from 0.95 to 0.99 for the femoral and tibial measurements, demonstrating near-perfect agreement.


CONCLUSIONS
The characterization of ACL tunnels has historically concentrated on two-dimensional (2D) measurements; however, it can be difficult to define ACL tunnel placement using 2D methods. We have presented novel techniques for defining graft tunnel placement from 3D surface representations of the ACL reconstructed knee. These measurements provide exact tunnel location spatially and along axes that offer the potential to comparatively analyze ACL reconstructions post-operatively using advanced imaging. These methods are reliable, and have been demonstrated to be applicable to multiple single-bundle techniques for ACL reconstruction.
Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.
Austin J
AJ
Ramme
Brian R
BR
Wolf
Bryan A
BA
Warme
Kiran H
KH
Shivanna
Michael C
MC
Willey
Carla L
CL
Britton
Vincent A
VA
Magnotta
Nicole M
NM
Grosland
D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D002102:Cadaver; D003198:Computer Simulation; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007719:Knee Joint / Q000601:surgery*; D015203:Reproducibility of Results; D014584:User-Computer Interface