The Correlation of Tunnel Position, Orientation and Tunnel Enlargement in Outside-in Single-Bundle Anterior Cruciate Ligament Reconstruction

Abstract

PurposeTunnel widening after anterior cruciate ligament (ACL) reconstruction is a frequently described phenomenon. The possible etiology is multi-factorial with some mechanical and biological factors. Among those, we intended to determine the relation between the location and orientation of the femoral tunnel and the femoral tunnel enlargement after outside-in single-bundle ACL reconstruction.Materials and MethodsA retrospective study including 42 patients who received single-bundle ACL reconstruction with the outside-in technique was conducted. Femoral and tibial tunnel locations were evaluated with the quadrant method and bird's-eye view using volume-rendering computed tomography. The angle and diameter of bone tunnel and the degree of tunnel enlargement were evaluated using standard radiographs.ResultsThe degree of femoral tunnel enlargements were 42% and 36% on the anteroposterior (AP) and lateral radiographs, respectively, and the degree of tibial tunnel enlargements were 22% and 23%, respectively. Shallower location of the femoral tunnel was significantly correlated with greater femoral tunnel enlargement on the AP radiograph (r=0.998, p=0.004) and the lateral radiograph (r=0.72, p=0.005) as was the higher location of the femoral tunnel on the AP radiograph (r=-0.47, p=0.01) and the lateral radiograph (r=-0.36, p=0.009) at 12 months after surgery.ConclusionsThis study revealed that more anterior and higher location and more horizontal orientation of the femoral tunnel in coronal plane could result in widening of the femoral tunnel in outside-in single-bundle ACL reconstruction.

A steep coronal graft bending angle is associated with bone tunnel enlargement of the posterolateral bundle after anterior cruciate ligament reconstruction

“…Bone tunnel enlargement also depends on the positioning of the bone tunnel, 11,13 with a more anterior and higher femoral tunnel position associated with greater widening of the femoral tunnel. 11 In the present study, there were no significant differences in the tunnel positions of the two groups.…”

“…7,8 Tunnel widening likely occurs due to a complex interplay between mechanical and biological factors. The reported mechanical factors include the "bungee effect" due to extracortical femoral fixation 9,10 and bone tunnel positioning, [11][12][13] while the biological factors include synovial fluid-derived cytokines and inflammatory mediators, bone quality, graft choice, and cell necrosis from drilling. 4,12,[14][15][16][17][18] Significant postoperative bone tunnel widening occurs at all four bone tunnels, with the greatest amount of widening occurring in the PLB tunnel.…”

Correlation between fixation systems elasticity and bone tunnel widening after ACL reconstruction

“…Nowadays radiological imaging upgrade can combine morphology and metabolism of ligaments like in PET-MRI, and some studies suggest that biological rearrangement, after ACL reconstruction, continues up to 24 months postoperatively 30 . However, in literature there are many attempt in order to modify tunnel widening, either from biological side, with the controversial use of PRP 31,32 , preserving ACL remnant 33 , hybrid graft 34 , alendronate 35 , manual drilling to reduce termical stress on bone 36 ; either from biomechanical side, improving tunnel position 37 and fixation systems stiffness. All these studies are conducted on little patient cohorts or on animal model, therefore it is desirable our little clinical experience would continue to also understand biological factors combined with biomechanical element.…”

A Comparative Study of Clinical Outcomes and Second-Look Arthroscopic Findings between Remnant-Preserving Tibialis Tendon Allograft and Hamstring Tendon Autograft in Anterior Cruciate Ligament Reconstruction: Matched-Pair Design

“…From these 3D CT images, placements of femoral and tibial tunnels were assessed by determining centers of femoral and tibial tunnel apertures. 8) To evaluate femoral tunnel placement, the quadrant method described by Bernard et al 9) was used for a true medial view of the femur ( Fig. 5 ).…”