gms | German Medical Science

Objectives: Meniscus extrusion has 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). The aim of the present study was to evaluate the influence of mountain ultramarathon running on the medial meniscus extrusion (MME) in healthy athletes. We hypothesized that such an extreme athletic activity would result in a reversible meniscal extrusion of more than 3 mm.

Methods: Healthy athletes of the 2017 Gore - Tex ® Transalpine run (7 stages with in total 267.4 km and 15 556 m altitude gain) with non-symptomatic knee, and no history of knee injuries or surgeries were included. Before the competition all athletes underwent standard knee examination, following MRI to exclude further knee pathologies and ultrasound (US) for measurement of MME. Extrusion in US was determined in supine position (unloaded) and in standing position with full weight bearing and 20° of flexion (loaded). After the 1st, 3rd, 5th and 7th stage ultrasound measurements were repeated. For evaluation of recovery function of the meniscus ultrasound measurements were also performed two weeks after the race.

Results and conclusions: 18 athletes (mean age 37,1 ± 8,1 years, 5 females, 13 males) met the inclusion criteria. The mean US MME before the race was 1.1 mm ± 0.4 mm in supine position (USE) and 2.0 mm ± 0.4 mm (USW) under full weight bearing. During the race the mean MME increased and at the final examination after 7th stage the mean MME in USE was 3.5 mm ± 0.8 mm and USW 3.6 mm ± 0.7 mm. However, preliminary results demonstrate a complete reversibility of the extrusion to normal.

The extreme loads generated by a mountain ultramarathon result in a reversible MME >3 mm even in healthy and asymptomatic knees. This shows, that the meniscus has elastic capacities and shows short term adaptions to high loads, which are probable reversible. Therefore meniscus extrusion should not only be defined as indirect static sign in MRI, but rather as an adaption reaction of the meniscus regarding full weight bearing and supine position.