Biomechanical analysis of knee hyperextension and of the impingement of the anterior cruciate ligament: a cinematographic MRI study with impact on tibial tunnel positioning in anterior cruciate ligament reconstruction

Abstract

This study analyzed the interaction between the anterior cruciate ligament (ACL) and the intercondylar notch roof (INR) in hyperextension of the knee using magnetic resonance cinematography. Cinematographic image series of 15 knees were investigated. Two independent observers identified the image that displayed the beginning of contact between the ACL and the INR. They determined knee extension on this image and on the image that displayed maximum hyperextension of the knee. Correlations between a variable representing impingement and the inclination angle of the INR, the anterior laxity of the knee, and full hyperextension were examined. Theoretical, impingement-free tibial tunnel positions for the knees were calculated as a percentage of the anteroposterior tibial width. All ACLs of the knees in this study made contact with the INR. The average extension angle at the beginning of impingement was -6.3 +/- 3.8 degrees. There were significant correlations between impingement and maximum manual displacement as measured with the arthrometer (r = 0.77; P < 0.001), maximum hyperextension (r = 0. 67; P = 0.007), and notch roof angle (r = -0.73; P = 0.002). There were biomechanically acceptable tunnel positions for all knees but one. Hyperextension is physiologically associated with impingement of the ACL. In uninjured knees there was a correlation between ACL impingement and hyperextension, inclination of the INR, and maximum manual displacement of the tibia. Impingement free tibial tunnel positioning is possible in most knees without notchplasty.

Intercondylar roof impingement pressure after anterior cruciate ligament reconstruction in a porcine model

“…One of the most serious concerns after ACL reconstruction is impingement of the graft against the intercondylar roof [6,[11][12][13][16][17][18]. To avoid this, many surgeons place the tibial tunnel in the posterior part of the ACL insertion site (PL insertion site) [4,14,24,26].…”

Anterior Cruciate Ligament Reconstruction Using Navigation

“…Following Julliard's philosophy, the software is used to optimize 2 criteria: identification of a minimal anisometry profile that is favorable (graft loosening in flexion) in the anatomical area of ACL insertion 26 and prevention of any conflict between the graft and the femoral notch. 13,14,17,18 Surgical Technique A standard surgical protocol was followed for both conventional and navigated procedures. All procedures were performed with the patient under general anesthesia and supine, and a tourniquet was placed above the knee.…”

“…There is an extensive debate on notch impingement in the literature, which is beyond the scope of this discussion, but we consider in this study that it must be avoided to prevent postoperative rupture of the graft in full extension. [16][17][18] It was interesting to note when looking at the tibial tunnels that the value CTT/STD (which characterizes the anterior positioning of the tibial tunnel with respect to the most anterior and posterior points of the tibial plateau measured on sagittal radiographs) was lower in the navigated group (31.4; range, 18.2-40) than in the conventional group (34.4; range, 22.2-43.4). Therefore, although the positioning was globally more anterior in the navigated group, the risk of notch impingement has been reduced.…”

Anterior Cruciate Ligament Reconstruction in Patients with Generalized Joint Laxity

“…In addition, there can be increased impingement of the reconstructed graft against the intercondylar roof in knees with excessive hyperextension, which in turn results in graft deterioration or re-rupture. Jagodzinski et al,66) in a cinematographic magnetic resonance imaging study, reported that impingement between the ACL and the intercondylar roof occurred at 6.3° hyperextension. They emphasized the importance of posterior placement of the tibial tunnel to avoid impingement in knees with increased hyperextension.…”