Tunnel position and graft orientation in failed anterior cruciate ligament reconstruction: a clinical and imaging analysis

Abstract

Purpose: It has been reported that technical error in positioning the graft tunnel is the most common problem in anterior cruciate ligament (ACL) reconstruction. The objective of this study was to quantitatively evaluate femoral and tibial tunnel positions and intra-articular graft orientation of primary ACL reconstruction in patients who had undergone revision ACL reconstruction. We postulated that this patient cohort had a nonanatomically positioned tunnel and graft orientation.

Methods: Twenty-six patients who had undergone a revision ACL were investigated. Clinical magnetic resonance (MR) images prior to revision were analysed. Three-dimensional models of bones and tunnels on the femur and tibia were created. Intra-articular graft orientation was measured in axial, sagittal and coronal planes. Graft positions were measured on the tibial plateau as a percentage from anterior to posterior and medial to lateral; graft positions on the femur were measured using the quadrant method.

Results: Sagittal elevation angle for failed ACL reconstruction graft (69.6° ± 13.4°) was significantly greater (p < 0.05) than that of the native anteromedial (AM) and posterolateral (PL) bundles of the ACL (AM 56.2° ± 6.1°, PL 55.5° ± 8.1°). In the transverse plane, the deviation angle of the failed graft (37.3° ± 21.0°) was significantly greater than native ACL bundles. The tibial tunnel in this patient cohort was placed posteromedially and medially to the anatomical AM and PL bundles, respectively. The femoral tunnel was placed anteriorly to the anatomical AM and PL bundles.

Conclusions: This study reveals that both the tibial and femoral tunnel positions and consequently the intra-articular graft orientation in this patient group with failed ACL reconstruction were nonanatomical when compared with native ACL values. The results can be used to improve tunnel placement in ACL reconstruction.

Figures

Fig. 1

Series of magnetic resonance images (MRI) of failed anterior cruciate ligament (ACL) reconstructed knee was used to build the three dimensional (3D) models of a the tibia and b the femur. A cylinder was fitted through the contours of the bone tunnels and its centre was regarded as the centre of the graft

Fig. 2

Definition of the a tibial and b femoral coordinate systems for tunnel position measurement; (t) direction parallel to the Blumensaat line, (h) direction perpendicular to the Blumensaat line. The position of normal anteromedial (AM) and posterolateral (PL) bundles are shown and compared with the position of the tunnel in failed anterior cruciate ligament (ACL) reconstruction. Black dots position of individual tunnels. Red circle average position of tunnels. Blue square position of AM bundle in normal knees. Green triangle position of PL bundle in normal knees

Fig. 3

a Coronal elevation angles of the anteromedial bundle (AMB), posterolateral bundle (PLB) and average of that in failed anterior cruciate ligament (ACL) graft. b Sagittal elevation angles of the AMB, PLB and average of that in failed ACL graft. c Deviation angles of the AMB, PLB and average of that in failed ACL graft

Fig. 4

Comparison of sagittal elevation, coronal elevation and deviation angles in failed anterior cruciate ligament (ACL) graft, normal anteromedial (AM) and posteromedial (PL) bundles. Sagittal elevation angle was significantly greater (vertical) in failed ACL reconstruction compared with normal ACL bundles, whereas the coronal elevation angle was not significantly different. Deviation angle of the ACL graft in the transverse plane was also significantly greater than that in the normal ACL bundles. (Data compared with [24])

Fig. 5

a Sagittal elevation angle of the failed anterior cruciate ligament (ACL) graft versus the position of its tibial tunnel in the anterior–posterior direction. b Coronal elevation angle of the failed ACL graft versus the position of its tibial tunnel in the medial–lateral direction