Medial meniscus extrusion increases with age and BMI and is depending on different loading conditions
Author(s):
Achtnich Andrea (Germany)
Achtnich Andrea (Germany)
Affiliations:
ESSKA Academy. Achtnich A. 05/09/18; 209724; P14-295 Topic: C3 - Meniscal root repair
Dr. Andrea Achtnich
Dr. Andrea Achtnich
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Abstract
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Objectives: Meniscus extrusion has always been described as an indirect sign of meniscus pathology and is associated with a loss of function of the affected meniscus. The current cut-off value of 3mm displacement is considered as abnormal and has been determined on magnet resonance images (MRI). However, it has to be considered that there is no description of the physiological meniscus extrusion in healthy knees depending on age and different weight bearing conditions. Therefore, it was hypothesized that in healthy knees there is a physiological age- and BMI- dependent meniscal extrusion, and meniscus extrusion depends on different loading conditions.

Methods: Healthy volunteers with non-symptomatic knee, and no history of knee injuries or operations were included in this prospective cross-sectional study. Exclusion criteria were age< 18years, subjective or objective instability, malalignment and positive meniscus test. Secondary exclusion criteria were osteoarthritis grade 3-4 and meniscus tear on MRI. Every patient underwent standard knee examination following measurement of medial meniscus extrusion (MME) using ultrasound (US). Extrusion was determined in supine position (unloaded) and under in standing position with full weight bearing and 20° of flexion (loaded). MRI was performed to compare ultrasound measurements with the current gold standard.

Results: 75 patients met the inclusion criteria. The mean US MME was 1.1 mm ± 0.5 mm in supine position and 1.9 mm ± 0.9 mm under full weight bearing. The mean US delta-extrusion was 0.8 mm ± 0,6 mm. All measurements of MME demonstrated a significant positive correlation for age. Furthermore BMI was significant correlated to US MME under full weight bearing (p = 0.002) and to US delta-extrusion (p = 0.003). In contrast, sex was not significant correlated to MME (NS). Results of MRI and US measurements in unloaded condition were comparable.

Conclusions: The present study demonstrates a significant correlation of MME with age and BMI in healthy volunteers. Furthermore MME was statistically significant correlated to axial loading conditions. Therefore, medial meniscus extrusion is an age-depending phenomenon in healthy knees and depends on various loadbearing conditions. Ultrasound examination of the MME might be favorable compared to MRI due to the ability of dynamic evaluation. As a consequence, the current cut-off value of 3mm for meniscus pathologies should be reconsidered.

Keywords:
Meniscal extrusion - ultrasound - MRI- weight bearing- healthy knee - dynamic extrusion
Objectives: Meniscus extrusion has always been described as an indirect sign of meniscus pathology and is associated with a loss of function of the affected meniscus. The current cut-off value of 3mm displacement is considered as abnormal and has been determined on magnet resonance images (MRI). However, it has to be considered that there is no description of the physiological meniscus extrusion in healthy knees depending on age and different weight bearing conditions. Therefore, it was hypothesized that in healthy knees there is a physiological age- and BMI- dependent meniscal extrusion, and meniscus extrusion depends on different loading conditions.

Methods: Healthy volunteers with non-symptomatic knee, and no history of knee injuries or operations were included in this prospective cross-sectional study. Exclusion criteria were age< 18years, subjective or objective instability, malalignment and positive meniscus test. Secondary exclusion criteria were osteoarthritis grade 3-4 and meniscus tear on MRI. Every patient underwent standard knee examination following measurement of medial meniscus extrusion (MME) using ultrasound (US). Extrusion was determined in supine position (unloaded) and under in standing position with full weight bearing and 20° of flexion (loaded). MRI was performed to compare ultrasound measurements with the current gold standard.

Results: 75 patients met the inclusion criteria. The mean US MME was 1.1 mm ± 0.5 mm in supine position and 1.9 mm ± 0.9 mm under full weight bearing. The mean US delta-extrusion was 0.8 mm ± 0,6 mm. All measurements of MME demonstrated a significant positive correlation for age. Furthermore BMI was significant correlated to US MME under full weight bearing (p = 0.002) and to US delta-extrusion (p = 0.003). In contrast, sex was not significant correlated to MME (NS). Results of MRI and US measurements in unloaded condition were comparable.

Conclusions: The present study demonstrates a significant correlation of MME with age and BMI in healthy volunteers. Furthermore MME was statistically significant correlated to axial loading conditions. Therefore, medial meniscus extrusion is an age-depending phenomenon in healthy knees and depends on various loadbearing conditions. Ultrasound examination of the MME might be favorable compared to MRI due to the ability of dynamic evaluation. As a consequence, the current cut-off value of 3mm for meniscus pathologies should be reconsidered.

Keywords:
Meniscal extrusion - ultrasound - MRI- weight bearing- healthy knee - dynamic extrusion
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