Femoral Graft-Tunnel Angles in Posterior Cruciate Ligament Reconstruction: Analysis with 3-Dimensional Models and Cadaveric Experiments

Abstract

PurposeThe purpose of this study was to compare four graft-tunnel angles (GTA), the femoral GTA formed by three different femoral tunneling techniques (the outside-in, a modified inside-out technique in the posterior sag position with knee hyperflexion, and the conventional inside-out technique) and the tibia GTA in 3-dimensional (3D) knee flexion models, as well as to examine the influence of femoral tunneling techniques on the contact pressure between the intra-articular aperture of the femoral tunnel and the graft.Materials and MethodsTwelve cadaveric knees were tested. Computed tomography scans were performed at different knee flexion angles (0°, 45°, 90°, and 120°). Femoral and tibial GTAs were measured at different knee flexion angles on the 3D knee models. Using pressure sensitive films, stress on the graft of the angulation of the femoral tunnel aperture was measured in posterior cruciate ligament reconstructed cadaveric knees.ResultsBetween 45° and 120° of knee flexion, there were no significant differences between the outside-in and modified inside-out techniques. However, the femoral GTA for the conventional inside-out technique was significantly less than that for the other two techniques (p<0.001). In cadaveric experiments using pressure-sensitive film, the maximum contact pressure for the modified inside-out and outside-in technique was significantly lower than that for the conventional inside-out technique (p=0.024 and p=0.017).ConclusionThe conventional inside-out technique results in a significantly lesser GTA and higher stress at the intra-articular aperture of the femoral tunnel than the outside-in technique. However, the results for the modified inside-out technique are similar to those for the outside-in technique.

Lower Tibial Tunnel Placement in Isolated Posterior Cruciate Ligament Reconstruction: Clinical Outcomes and Quantitative Radiological Analysis of the Killer Turn

“…Several studies have evaluated graft tunnel angles using 3D CT. 15 , 18 , 20 , 27 , 28 , 34 However, those measurements considered the angles on only 2-dimensional planes (ie, sagittal or coronal projections) rather than in 3D space, and it is difficult to evaluate the true angle of the killer turn with such data. Our assessment method, by which we measured the killer turn in 3D space using 3D coordinates, provides a more reliable means of evaluating and comparing the angles created by different techniques.…”

“…However, to the best of our knowledge, the clinical outcomes of this technique using a lower tibial tunnel have not been reported. Furthermore, although quantitative radiological assessments of the killer turn 15 , 18 , 20 , 27 , 28 , 34 have been reported, the angles were measured on 2-dimensional coronal, sagittal, or axial projections, which yield different results from the true angles in 3-dimensional (3D) space.…”

Tunnel Enlargement Correlates With Postoperative Posterior Laxity After Double-Bundle Posterior Cruciate Ligament Reconstruction

“…11,22 Moreover, there will likely be high mechanical stress between the PCL graft and the tunnel wall at the tunnel aperture such as killer turn for the tibia 6,19,21 and the critical bending angle for the femur. 8,16 These mechanical factors cause significant tunnel enlargement at the aperture in each tunnel in the early postoperative term.…”

A Prospective Assessment of an Adjustable, Immediate Fit, Transtibial Prosthesis

“…This film is quite thin (4 to 8 mils), which enables it to conform to curved surfaces and is useful for intrasocket interfaces. It has been used in studies to evaluate joint contact pressures in cadaveric knees . For this study, the Fujifilm paper was taped to five different sites on the silicone liner: anterior tibia, medial limb, lateral limb, posterior, and bottom.…”

“…It has been used in studies to evaluate joint contact pressures in cadaveric knees. 13,14 For this study, the Fujifilm paper was taped to five different sites on the silicone liner: anterior tibia, medial limb, lateral limb, posterior, and bottom. Color changes were rated for each participant at each site within the socket by a single research coordinator.…”