2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


Patients with Medial Meniscus Posterior Root Tear Have Larger Medial Femoral Condyle Angle

Kensuke Hotta, MD, Hamamatsu, Shizuoka JAPAN
Mitsuru Hanada, MD, PhD, Hamamatsu, Shizuoka JAPAN
Yukihiro Matsuyama, MD, PhD, Hamamatsu, Shizuoka JAPAN

Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, JAPAN

FDA Status Not Applicable

Summary

This study examines the relationship between medial meniscus posterior root tear (MMPRT) and bone morphology. Among 103 patients, significant differences were observed in medial proximal tibial angle, medial femoral condyle angle, condylar twist angle, and notch width/intercondylar distance between MMPRT and non-MMPRT groups, highlighting distinct bone features in MMPRT patients.

Abstract

Introduction

Early repair of medial meniscus posterior root tear (MMPRT) is crucial due to its potential to cause progressive knee osteoarthritis. While risk factors such as advanced age, female gender, squatting movements, high BMI, and varus knee have been identified, the specific bone morphology associated with MMPRT remains unclear. This study aims to evaluate differences in bone morphology between patients with and without MMPRT.

Methods

• Patient Selection: Patients diagnosed with MMPRT, spontaneous osteonecrosis of the knee (SONK), or early osteoarthritis (EOA) at our institution between 2016 and 2023 were included. MRI images were used to measure the posterior tibial slope (PTS) in the sagittal plane, medial proximal tibial angle (MPTA) in the coronal plane, notch width (NW)/intercondylar distance (ICD), condylar twist angle (CTA), and medial femoral condyle angle (MFCA) in the horizontal plane. MMPRT was defined by the presence of a vertical linear sign on the coronal plane or a white meniscus sign on the sagittal plane. Patients were divided into two groups: Group M (with MMPRT) and Group N (without MMPRT). Parameters were compared between the two groups.
• MRI Parameters:
o PTS: In the sagittal plane, the angle between the proximal tibial articular surface and a line perpendicular to the line connecting the anteroposterior center of the tibia, measured at a level 5 cm distal and 1 cm proximal to the proximal tibial articular surface.
o MPTA: In the coronal plane, the angle formed between a line connecting the medial and lateral central points at two distinct levels (5 cm distal and 1 cm proximal from the most distal part of the imaging range) and the proximal articular surface of the tibia.
o MFCA: The angle between the lines connecting the centers of two circles tangent to the anterior and posterior parts of the medial femoral condyle in the horizontal plane.
o CTA: The angle formed between the surgical epicondylar axis (SEA) and the posterior condylar angle (PCA), with positive values indicating external rotation of the SEA relative to the PCA.
o NW: The posterior-most distance of the femoral intercondylar notch.
o ICD: The distance between the medial and lateral femoral epicondyles.
• Statistical Analysis: Comparisons of patient demographics and MRI parameters were conducted using t-tests, with categorical variables such as sex compared via chi-square tests. All statistical analyses were performed using SPSS version 29 (IBM Corporation, Armonk, New York, USA). A p-value of less than 0.05 was considered statistically significant.

Results

A total of 103 patients were included, with 55 in Group M and 48 in Group N. Group M exhibited a significantly smaller MPTA (86.8° vs. 87.8°, p<0.001), a significantly larger MFCA (48.2° vs. 43.6°, p<0.001), a significantly larger CTA (3.9° vs. 3.1°, p=0.024), and a significantly smaller NW/ICD (0.249 vs. 0.263, p=0.01) compared to Group N.

Discussion

This study found that patients with MMPRT had a smaller MPTA, a larger MFCA, a larger CTA, and a smaller NW/ICD. The smaller MPTA likely reflects an increased medial sliding force of the femur, while the larger MFCA and CTA may be linked to increased rotational forces at the MMPR site. Additionally, the smaller NW/ICD may result from increased load on the MMPR site due to the medial overhang between the condyles.

Conclusion

A narrow intercondylar notch, larger medial femoral condyle angle, larger condylar twist angle, and smaller medial proximal tibial angle are associated with MMPRT.