The Role of the Posterolateral Tibial Slope in the Rotational Instability of the Knee in Patients Affected by a Complete Isolated Anterior Cruciate Ligament Injury: Its Value in the Decision-Making Process during the Anterolateral Ligament Reconstruction

Abstract

Purpose The aim of this retrospective, multicenter study was to investigate the correlation between a high degree of rotatory instability, posterolateral tibial slope (PLTS), and anterolateral ligament (ALL) injury. Methods The study population consisted of 76 adults with isolated, complete noncontact anterior cruciate ligament (ACL) tear. The sample was divided into two groups according to the preoperative degree of rotator instability (group A: pivot-shift test grades 2 and 3; group B: pivot-shift test grade 1). Preoperative magnetic resonance imaging (MRI) assessment included angle of PLTS, posterior shift of the lateral femoral condyle (16 mm) on the tibial plateau, and the presence/absence of ALL injury. The two groups were compared for differences. Results There was a statistically significant association between pivot-shift test grades 2 and 3 (group A), PLTS slope angle > 9 degrees, and ALL injury (p < 0.05). Group A also demonstrated a greater posterior shift of lateral femoral condyle (>11 mm), which was, however, not statistically significant when evaluated as an isolated variable. Conclusion Our study indicates that an increased PLTS is associated with an increased incidence of ALL injury and an increased grade of pivot shift in patients with ACL tear. Assessment of posterolateral tibial slope on MRI can therefore play a key adjunct role in the surgical planning of ALL reconstruction, especially in cases when ALL damage is radiologically difficult to detect or doubtful. Level of Evidence This is a retrospective comparative level III study.

Posterior Tibial Slope in Patients Undergoing Bilateral Versus Unilateral ACL Reconstruction: MRI and Radiographic Analyses

“…An important finding in the current study is that while the PTS on radiography and the LPTS on MRI were significantly greater in patients with bilateral ACLR, this result was not reflected in the MPTS compared between the bilateral and unilateral groups. Interestingly, Bargagliotti et al 1 also observed a higher LPTS (measured on MRI) when comparing patients who sustained noncontact ACL ruptures based on high-degree (grade 2 and 3 pivot shift) or low-degree (grade 1 pivot shift) rotatory instability. They found a significant association between the high-grade instability group with anterolateral ligament injuries and an LPTS >9°, suggesting that bony morphology in the lateral compartment may have an important relationship with rotational instability.…”

Steeper lateral posterior tibial slope and greater lateral-medial slope asymmetry correlate with greater preoperative pivot-shift in anterior cruciate ligament injury

“…Some previous studies have shown that a steeper PTS is a risk factor for a high-grade pivot-shift test [ 3 , 4 , 27 ]. Batty et al analyzed 618 ACL-injured patients and found that PTS > 9°, measured by lateral plain radiograph, was one of the six factors associated with high-grade pivot-shift [ 4 ].…”

“…Another study has shown that lateral PTS measured by MRI was significantly greater in a “high-grade rotatory laxity” group (9.3° ± 3.4°) compared to a “low-grade rotatory laxity” group (6.1° ± 3.7°) based on quantitatively assessed pivot-shift test with the image analysis using an iPad [ 27 ]. A significant association has also been reported between lateral PTS > 9° and high-grade pivot-shift, and anterolateral ligament injury, while medial PTS was not significantly different between low-grade and high-grade groups [ 3 ]. However, as limitations of the previous studies, the association between medial–lateral PTS asymmetry and the pivot-shift was not assessed, and only one study [ 27 ] quantitatively assessed pivot-shift test by using iPad image analysis [ 10 ] among the three studies [ 3 , 4 , 27 ].…”

“…A significant association has also been reported between lateral PTS > 9° and high-grade pivot-shift, and anterolateral ligament injury, while medial PTS was not significantly different between low-grade and high-grade groups [ 3 ]. However, as limitations of the previous studies, the association between medial–lateral PTS asymmetry and the pivot-shift was not assessed, and only one study [ 27 ] quantitatively assessed pivot-shift test by using iPad image analysis [ 10 ] among the three studies [ 3 , 4 , 27 ]. The present study found that not only lateral PTS but also medial–lateral PTS asymmetry were significantly correlated with tibial acceleration during the pivot-shift test, which is a novel finding compared to the previous studies [ 3 , 4 , 27 ].…”

“…Especially, steeper posterior tibial slope (PTS) has been recognised as a potential risk factor for ACL injury [ 7 ], ACL graft failure [ 29 ], and post-operative static anterior tibial translation [ 19 ]. In terms of anterolateral rotatory knee laxity, several studies have shown that steeper PTS is associated with a high-grade pivot-shift which was evaluated by subjective grading [ 3 , 4 , 31 ]. Another study has shown that not only lateral PTS but also lateral-medial slope asymmetry were risk factors for concomitant posterolateral meniscal root tears in ACL injuries, suggesting lateral-medial slope asymmetry causes tibiofemoral rotation and increases the load on the posterolateral meniscus root [ 17 ].…”