Summary

Lateral compartment geometry, especially increased lateral plateau width, lateral plateau length, lateral condyle width and lateral tibial slope, seem to be a risk factor for concomitant medial meniscus injury in patients with an ACL injury.

Abstract

Introduction

Bony anatomy of the knee has recently been recognized as an important factor in knee stability and for its role in the ACL injury mechanism. Decreased plateau sizes and increased tibial plateau slope have been identified as predisposing conditions for ACL injury and ACL reconstruction failure [1]. However, the influence of bony morphology on the integrity of the menisci after ACL injury has not yet been thoroughly investigated. The purpose of this study was to determine whether tibial and femoral bony anatomy is associated with concomitant meniscus injury in patients with ACL injury.

Methods

The Magnetic Resonance Imaging (MRI) of N=112 ACL injured patients (mean age: 28.4 ± 9.9 years) undergoing primary ACL reconstruction were examined for bony morphology parameters. Meniscal injury was determined by operative note.
Blinded to the meniscus status of the patients, the bony morphology characteristics were evaluated by two independent observers in preoperative T1 coronal and sagittal MRI sequences. Measurements included medial-lateral (ML) diameter of the medial tibial plateau (MTP), lateral tibial plateau (LTP), medial femoral condyle (MFC), lateral femoral condyle (LFC), notch width (NW), and bicondylar width (BW). Medial tibial posterior slope (MTPS) and lateral tibial posterior slope (LTPS) were determined by established methods [2]. Data were collected in Excel (Microsoft Corp.) and analyzed in SPSS (version 22.0, SPSS Inc., Chicago, USA) using logistic regression and t-test.

Results

Of the 112 ACL injured patients enrolled, 38 had lateral meniscus injury and 46 had medical meniscus injury. Although lateral meniscus injury was not significantly associated with any bone morphology parameter, patients with medial meniscus injury had increased LFC width, LTP width, LTP length, and LTPS (Table 1). Logistic regression analysis revealed that, independently, every 1mm increase in lateral femoral condyle width (p=0.046) and lateral tibial plateau width (p=0.04) increased the odds for medial meniscus tears by 13%. Every 1mm increase in lateral plateau length (p=0.013) increased the odds by 10%, and each 1° increase in lateral posterior tibial slope (p=0.048) increased the odds by 13% (Table 2).

Discussion

The most significant finding of this study is that bone morphology of the lateral compartment was significantly associated with medial meniscal injury in ACL injured patients. Although it is known that LTP size and LTPS are influencing variables for the magnitude of pivot shift and predispose patients to ACL injury [3,4], the role of tibial and femoral bone anatomy in concomitant meniscus injuries is not well understood. This study indicates that similar morphological parameters also act a role in meniscal injury. Given the geometry of the lateral compartment, especially the convexity of the lateral tibial plateau, an influence on the rotatory stability and envelope of motion can be associated. Identifying risk factors and understanding the biomechanical consequences could help identifying patients at increased risk for osteoarthritis that accompanies meniscal lesions and potentially prevent these degenerative processes.

[1] Musahl, KSSTA 2010
[2] Hudeck, Orthop Relat Res 2009
[3] Brandon, Arthroscopy 2006
[4] Kujala, Arch Orthop Trauma Surg 1992