Do knees survive the Comrades Marathon? An MRI Study

Abstract

Objective: To detect by MRI imaging the presence and type of knee injuries in non-professional runners after running an ultra-marathon. To determine whether ultra-marathon running exacerbates pre-existing knee injuries or results in new permanent injuries.

Design: A prospective MR study of randomly selected knees of ten participants who completed the Comrades Marathon in the period between 1997 and 2002. Knees were scanned 48 hours before the race, and 48 hours and one month following the race.

Setting: All scans were performed at the Radiology Department, Wentworth Hospital, Durban and the University of KwaZulu Natal.

Main Outcome Measures: Scores of all knee injuries detected on magnetic resonance scans immediately before the race which were compared with the scores after the race.

Results: All knees scanned demonstrated an abnormal amount of joint fluid before the race that had increased immediately after the race in 5 runners and remained unchanged in the other five. One month later, 5 runners showed decreased joint fluid and 5 remained unchanged, but these were not the same as in the post-race groups. Increased signal intensity in the distal patellar and quadriceps tendons was observed in 4 runners before the race and this increased or remained the same on post-race scans in 6. There was a decrease in signal intensity on scans taken one month later in 3 with complete resolution in 2 and unchanged in 1. Old injuries to ligaments, tendons or other knee structures were unaffected by the race. No bone bruising, cartilage defects or meniscal abnormalities were observed. There was no significant difference in the pre- and post-race scan scores or the one-month follow-up scan score.

Conclusions: The race appears to have a detrimental effect on runners who start the ultra-marathon with tendinopathy, which worsens post-race by MRI criteria. One month after the race, the scan appearance of the overuse injury has either improved or has resolved completely. Bone bruising or meniscal damage does not appear to occur and the presence of increased joint fluid probably relates to stress or injury.