The Graft/Femoral Tunnel Angles in Posterior Cruciate Ligament Reconstruction –A Comparison of 3 Techniques for Femoral Tunnel Placement

Abstract

This study compared the graft/femoral tunnel angle produced with the outside-in technique with the inside-out technique at 90° and 120° of flexion. Three femoral tunnels were marked with guidewires and measured radiographically in 8 fresh-frozen cadaveric knees using both techniques. Results were analyzed. The mean graft/femoral tunnel angle was 34.4°614.4° for the outside-in technique, 52.3°614.1° for the inside-out technique at 120° of flexion, and 74.4°611° for the inside-out technique at 90° of flexion. The angle was smaller for the outside-in technique versus the inside-out technique at both 120° (P = .019) and 90° of knee flexion (P , .001). The outside-in technique for femoral tunnel placement produces the lowest graft/femoral tunnel angle in cadavers. With the inside-out technique, 120º of flexion produces smaller angles than does 90º of flexion. The outside-in technique results in lower angles and perhaps lower graft failure rates. However, additional clinical studies are needed. [J Knee Surg. 2009;22:106-110.]

Optimal Femoral Tunnel Positioning in Posterior Cruciate Ligament Reconstruction Using Outside-in Drilling

“…We included the so-called "critical corner" as a variable in our regression models because sharp femoral graft/tunnel angles may contribute to attritional graft stress, ultimately resulting in graft failure. 13,[20][21][22] We chose a maximum acceptable graft/ OPTIMAL FEMORAL TUNNEL POSITIONING femoral tunnel angle of 50 in accordance with previously published studies that have quantitated the "critical corner" in outside-in PCL reconstruction. 13,21 In a cadaveric biomechanics study, Handy et al 21 found that the outside-in femoral drilling technique produces a significantly less acute angle at the femoral aperture relative to the inside-out technique (50 and 87 for the outside-in and inside-out drilling groups, respectively).…”

“…Similarly, a different cadaveric study also found reduced graft/ tunnel angles in a group that underwent outside-in drilling compared with a group that underwent inside-out drilling. 13 The authors of that study concluded that reduction of the "critical corner" might lower graft failure rates. However, the literature does not unanimously show the superiority of the outside-in drilling technique.…”

“…On the femoral side of arthroscopic PCL reconstruction, outside-in drilling has grown in favor as a means to avoid sharp graft angulation and potential graft abrasion or failure. 13 Some authors posit that the use of outside-in drilling can reduce the graft angle as it enters the femoral socket at the so-called "critical corner." 14 However, there exists a paucity of research investigating the optimal method for creating the femoral socket during outside-in PCL reconstruction.…”

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

“…A variety of surgical techniques and graft materials have been used for PCL reconstruction,1 but the procedure remains challenging. Several authors have reported that the grafted substances can become stretched due to the concentration of stress caused by the acute angle between the graft and the intra-articular apertures of the tunnels 2-7. In arthroscopic PCL reconstruction, femoral tunnels can be created with either the outside-in (two-incision) or inside-out (one-incision) techniques.…”

“…The inside-out technique makes the femoral socket through the anterolateral portal 8,9. Although the inside-out technique minimizes potential injury to the vastus medialis obliquus, several researchers have suggested that it sharpens the femoral graft-tunnel angle formed between the graft and the intra-articular aperture of the femoral tunnel, causing increased attritional stress 5-7. However, most studies for the femoral graft-tunnel angle have been performed in the context of two dimensions rather than three dimensions, and no studies have determined whether the results vary in relation to the flexion angle of the knee.…”