Summary

Combined ACL and ALL reconstruction significantly improves rotational knee laxity in patients with high-grade pivot shift, offering crucial stabilization in severe cases and preventing residual instability after isolated ACL reconstruction.

Abstract

Background

Anterolateral ligament (ALL) reconstruction combined with anterior cruciate ligament (ACL) reconstruction is being recognized for its ability to enhance rotational knee stability, particularly in patients presenting with a high-grade pivot shift, which is often associated with severe knee laxity. This study aims to assess the effectiveness of combined ACL and ALL reconstruction in improving intraoperative knee laxity in patients with a high-grade pivot shift, utilizing quantitative evaluation under anesthesia.

Methods

Patients who underwent primary ACL and ALL reconstruction between June 2016 and July 2024 were retrospectively included. Exclusion criteria were concomitant ligament reconstruction, other ligament injuries, and no quantitative measurement data. Patients were divided into two groups based on the preoperative pivot shift test IKDC Grade: The Severe Group (S group, Grade 3) and the Mild/Moderate Group (M group, Grades 0-2). Knee laxity was measured under anesthesia at preoperatively, ACL reconstruction, and ALL reconstruction. The side-to-side difference in anterior tibial translation (ATT), and side-to-side ratio of tibial acceleration and external rotational angular velocity (ERAV) during the pivot-shift test were recorded in each group. Statistical analysis was performed using the Mann-Whitney U test, with significance set at 5%.

Results

Of 120 primary ACL and ALL reconstructions performed, 82 patients met inclusion criteria and were analyzed, with 46 classified into the S group and 36 into the M group. Preoperative knee laxity was significantly greater in the S group for ATT, acceleration, and ERAV (all p <0.001). During ACL reconstruction, acceleration and ERAV were higher in the S group compared to the M group (acceleration: 1.4 vs. 1.2, p=0.098; ERAV: 1.4 vs. 1.1, p=0.046). However, during ALL reconstruction, these differences decreased, with no significant differences between the groups in ATT (p=0.539), acceleration (p=0.638), or ERAV (p=0.533). The difference in ERAV between ACL and ALL reconstruction was significantly greater in the S group compared to the M group (0.4 vs 0.2, p=0.044).

Discussion

The findings suggest that combined ACL and ALL reconstruction is highly effective for patients with severe knee laxity, particularly those with a high-grade pivot shift. This approach significantly improves rotational laxity, a key factor in knee stability. The reduction in preoperative laxity observed during ALL reconstruction underscores its crucial role in addressing rotational laxity, which isolated ACL reconstruction may not fully correct, especially in severe cases. ALL reconstruction enhances ACL reconstruction's stabilizing effects, making it a valuable technique for managing severe knee laxity. This procedure not only improves stability but also leads to better outcomes for patients with high-grade knee laxity. Integrating ALL reconstruction is essential for achieving comprehensive knee stability and preventing long-term complications in patients with severe instability.

Conclusion

Combined ACL and ALL reconstruction significantly improve rotational laxity in patients with high-grade pivot shift, as shown by quantitative evaluation under anesthesia. This approach not only addresses anterior instability typically managed by ACL reconstruction but also effectively rotational laxity, crucial in severe cases. Therefore, this procedure should be considered essential in managing severe knee laxity, particularly in patients at risk of residual instability after isolated ACL reconstruction.