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bibliography*The PainScience Bibliography contains plain language summaries of thousands of scientific papers and others sources, like a specialized blog. This page is about a single scientific paper in the bibliography, Malliaropoulos 2010.

Moderate muscle strains reinjured more than twice as much as mild or severe


Tags: strain, counter-intuitive, etiology, injury, pain problems, muscle, pro

PainSci summary of Malliaropoulos 2010?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★☆☆?3-star ratings are for typical studies with no more (or less) than the usual common problems. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.

It is common for hamstring strains to recur. How common, and what is the effect of the severity of the injury? Counter-intuitively, this study of 165 elite athletes found that moderate strains (grade II) were reinjured at more than double the rate of mild and severe strains (grades I and III): about 24%, compared to 9% and 8%! That’s a substantial difference.

Off the top of my head, I have absolutely no idea why moderate strains would be more prone to re-injury. It’s intriguing.

original abstractAbstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: Hamstring muscle strains often recur. The authors studied the effect of the grade of initial injury on the subsequent risk of reinjury.

HYPOTHESIS: No difference in reinjury rate between acute low-grade (grades I and II) and high-grade (III and IV) hamstring muscle strains would be seen.

STUDY DESIGN: Cohort study (prognosis); Level of evidence, 1.

METHODS: Between 1999 and 2007, the authors managed 165 elite track and field athletes with acute, first-time unilateral hamstring muscle strains. Strains were classified into 4 grades (I, II, III, and IV) based on knee active range of motion deficit at 48 hours. The same rehabilitation protocol was prescribed, and the rate of reinjury was recorded during the following 24 months.

RESULTS: The average time to return to sport after initial injury was 7.4 days for grade I injuries, 12.9 days for grade II injuries, 29.5 days for grade III injuries, and 55.0 days for grade IV injuries. At follow-up, 23 of the 165 athletes (13.9%) had experienced a second hamstring muscle strain. Of the 75 athletes with a grade I injury, 7 (9.3%) had experienced a recurrence after 24 months. Of the 58 athletes with a grade II injury, 14 (24.1%) experienced a recurrence. Of the 26 athletes with a grade III injury, 2 (7.7%) experienced a recurrence, and of the 6 athletes with a grade IV injury, none had experienced a recurrence after 24 months.

CONCLUSION: Low-grade hamstring muscle lesions appear to lead to a higher risk of reinjury than high-grade hamstring muscle lesions. However, there were disproportionately fewer high-grade injuries than low-grade injuries. Objective clinical findings can accurately determine the risk of reinjury after acute hamstring muscle strains in elite track and field athletes.

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One article on cites Malliaropoulos 2010 as a source:

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