2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


Serial Magnetic Resonance Imaging Studies of Arthroscopic Reshaping for Symptomatic Discoid Lateral Meniscus in Childeren and Adolescents

Sang Hak Lee, MD, PhD, Seoul KOREA, REPUBLIC OF
Jun-Ho Kim, MD, Anyang-Si, KOREA, REPUBLIC OF
Sunin Yoo, MD, Seoul KOREA, REPUBLIC OF

kyunghee university hospital at gangdong, seoul, KOREA, REPUBLIC OF

FDA Status Not Applicable

Summary

Arthroscopic surgery can benefit children and adolescents with DLM, as it improves meniscus intensity, morphology, and diastasis, despite reductions in coronal width, and posterior horn thickness and width.

Abstract

Introduction

No consensus has been reached with regard to the status of the articular cartilage, as well as of the meniscus after arthroscopic surgery for symptomatic discoid lateral meniscus (DLM). The aim of this study was to analyze the status of remaining meniscus and articular cartilage of lateral compartment in patients with arthroscopic reshaping for symptomatic DLM in children and adolescents who underwent serial postoperative magnetic resonance imaging (MRI).

Material

This study included 51 knees with 42 patients who underwent arthroscopic partial meniscectomy with or without repair for symptomatic DLM and had at least 2 postoperative MRI studies. The mean age at the time of surgery was 11.1±3.9 years (range, 3 to 20). Mean interval between first and second imaging studies was 30.34±24.9 months. Radiological parameters were analyzed using MRI, specifically the mid coronal and sagittal views, focusing on (1) meniscus size, (2) meniscus signal intensity, morphology and diastasis, and (3) cartilage condition. Meniscus size was assessed in terms of width and thickness in both the coronal and sagittal views. The signal intensity, diastasis, and morphology were each classified as high(2), intermediate(1), or low based(0) on their respective criteria. The degree of extrusion of the lateral meniscus (LM) was calculated as the Relative Percentage of Extrusion (RPE). Clinical outcomes were evaluated at the final follow up according to Tegner activity level, Lysholm score, and Hospital for Special Surgery (HSS) scores. Wilcoxon sign rank test, paired t-test, Pearson's chi-squared test, Fisher's exact test were performed statistically using SPSS version 25.0 statistical software.

Results

When comparing MRI results, the relative coronal LM width and thickness significantly decreased from 12.67% to 11.02% and from 10.87% to 9.97%, respectively (P<0.05), while no significant change was observed in the RPE (Relative Percentage of Extrusion). Similarly, in the relative sagittal LM, the posterior horn showed a significant reduction in both width, from 23.35% to 22.88%, and thickness, from 20.54% to 18.51% (P<0.05). This pattern was also evident in the anterior horn, where the width decreased significantly from 29.65% to 26.73%, and the thickness decreased from 15.63% to 14.53% (P<0.05).
Signal intensity improved in all regions: from 1.2 ± 0.7 to 0.3 ± 0.5 in the AH (anterior horn), from 1.5 ± 0.6 to 0.4 ± 0.5 in the MB(midbody), and from 1.0 ± 0.6 to 0.16 ± 0.37 in the PH (posterior horn). (<0.001) Morphology improved across all regions: from 0.94 ± 0.68 to 0.23 ± 0.42 in the AH, from 1.19 ± 0.7 to 0.2 ± 0.4 in the MB, and from 0.52 ± 0.5 to 0.2 ± 0.4 in the PH. (<0.001) Diastasis improved from 0.90 ± 0.70 to 0.45 ± 0.67 in the MB and from 0.55 ± 0.6 to 0.16 ± 0.3 in the PH (P<0.001), but there was no significant difference in the AH.
In terms of cartilage condition, there was a statistically significant deterioration only in the F2 area (P<0.05), while no differences were observed in other regions. Additionally, a comparison of clinical scoring pre-operation and at the final follow-up showed significant improvement in all three measures (P<0.05).
To analyze the risk factors associated with a decrease in relative coronal LM width, participants were divided into two groups based on a 15% threshold: a conserved group and a decreased group. There were no significant differences between the groups in terms of age, sex, BMI, or type of shift. However, when the LM extrusion measured in the first MRI was ≥3 mm, a statistically significant decrease in the coronal size of the LM was observed in the second MRI (P<0.05).

Results

Mild changes were observed in the cartilage, and the overall size of the meniscus appeared to decrease after surgery. However, the remaining meniscus showed significant improvements in intensity, morphology, and diastasis, except for anterior horn diastasis. Additionally, all clinical symptoms improved.Subgroup analysis revealed that when LM extrusion measured ≥3 mm on the first postoperative MRI, there was a higher likelihood of poor outcomes, suggesting it may serve as an indicator of the severity of the tear before surgery. Nevertheless, in most cases, arthroscopic surgery is considered an effective treatment for children and adolescents with DLM.