The Association Between Concomitant Meniscal Tear, Tibial Slope, Static Knee Position, and Anterior Knee Laxity in ACL-Deficient Patients.

Abstract

Background: Whether the tibial slope or the concomitant meniscal tear is related to static knee position or anterior knee laxity remains controversial.

Purpose: To investigate the association between medial and lateral posterior tibial slope, concomitant meniscal tear, static knee position using magnetic resonance imaging (MRI), and anterior knee laxity measured with the GNRB arthrometer.

Study design: Cross-sectional study; Level of evidence, 3.

Methods: A total of 60 patients who underwent anterior cruciate ligament (ACL) reconstructions were retrospectively enrolled from May 2020 to October 2022. All patients underwent both MRI and GNRB arthrometry after the injury. The static knee position and medial and lateral tibial slopes were measured using MRI. The meniscal tear type was confirmed during arthroscopic surgery. Descriptive data were retrospectively reviewed from the medical records.

Results: The side-to-side differences of anterior tibial translation at 134 N in the intact meniscus, isolated lateral meniscal tear, isolated medial meniscal tear, and both meniscal tear groups were 3.63 ± 1.4 mm, 4.61 ± 1.5 mm, 2.85 ± 1.5 mm, and 4.85 ± 1.6 mm, respectively (P = .003). The slopes of the force-displacement curve in the GNRB arthrometer were 6.55 ± 4.8 mm/N, 16.99 ± 5.6 mm/N, 9.69 ± 10.8 mm/N, and 10.89 ± 7.4 mm/N in the intact meniscus, lateral meniscal tear, medial meniscal tear, and both meniscal tear groups, respectively (P = .001). Subgroup analysis showed that patients with lateral meniscal tears tended to have greater anterior knee laxity based on the GNRB arthrometer tests. The medial and lateral tibial slopes were not correlated with static knee position or anterior knee laxity.

Conclusion: Patients with ACL deficiency and concomitant lateral meniscal tears are more likely to exhibit greater anterior knee laxity, as measured using the GNRB. Clinicians should consider the concomitant lateral meniscal tear when planning surgery and arranging postoperative care. Tibial slopes were not found to be correlated with static knee position or anterior knee laxity.