New MRI muscle classification systems and associations with return to sport after acute hamstring injuries: a prospective study



To determine agreement between modified Peetrons, Chan acute muscle strain injury classification and British Athletics Muscle Injury Classification (BAMIC) and to investigate their associations and ability to predict time to return to sport (RTS).


Male athletes (n=176) with acute hamstring injury and MRI (1.5T) ≤5 days were followed until RTS. MRIs were scored using standardised forms.


For MRI-positive injuries there was moderate agreement in severity grading (κ = 0.50–0.56). Substantial variance in RTS was demonstrated within and between MRI categories. Mean differences showed an overall main effect for severity grading (p < 0.001), but post hoc pairwise comparisons for BAMIC (grade 0a/b vs. 1, p = 0.312; 1 vs 2, p = 0.054; 0a/b vs 2, p < 0.001; 1 vs 3, p < 0.001) and mean differences for anatomical sites (BAMIC a–c, p < 0.001 [a vs b, p = 0.974; a vs c, p = 0.065; b vs c, p = 0.007]; Chan anatomical sites 1–5, p < 0.077; 2A–C, p = 0.373; 2a–e, p = 0.008; combined BAMIC, p < 0.001) varied. For MRI-positive injuries, total explained RTS variance was 7.6–11.9% for severity grading and BAMIC anatomical sites.


There was wide overlap between/variation within the grading/classification categories. Therefore, none of the classification systems could be used to predict RTS in our sample of MRI-positive hamstring injuries.

Key points

Days to RTS varied greatly within the grading and classification categories.

Days to RTS varied greatly between the grading and classification categories.

Using MRI classification systems alone to predict RTS cannot be recommended.

The specific MRI classification used should be reported to avoid miscommunication.

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The authors would like to thank the staff of the Qatar National Sports Medicine Program (NSMP), the Sports Medicine Physicians and the staff in the Outpatient Department, and the staff of the Radiology Department, the Rehabilitation Department and the Surgery Department at Aspetar for their contribution to the study. Our sincere thanks are directed to Aziz Farooq for assisting with the statistical analysis.


The authors state that this work has not received any funding.

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Corresponding authors

Correspondence to Arnlaug Wangensteen or Johannes L. Tol.

Ethics declarations


The scientific guarantor of this publication is Arnlaug Wangensteen

Conflict of interest

The following authors of this manuscript declare relationships with the following companies:

Outside the submitted work, AG is a consultant to Pfizer, AstraZeneca, Merck Serono, Sanofi-Aventis, GE Healthcare, TissueGene and OrthoTrophix. AG is also president and a shareholder of Boston Imaging Core Lab, LLC (BICL), which provides image assessment services. FWR is a shareholder of BICL. JLT’s institutes have received funding from Arthrex and Biomet for conducting RCTs on the value of PRP in hamstring and Achilles tendon injuries. JLT received no personal compensation.

Statistics and biometry

Abdulaziz Farooq kindly provided statistical advice for this manuscript.

Ethical approval

Institutional Review Board approval was obtained.

Informed consent

Written informed consent was obtained from all subjects (patients) in this study.

Study subject or cohort overlap

Some study subjects have been previously reported in:

Wangensteen A, Tol JL, Roemer FW, Bahr R, Dijkstra HP, Crema MD, Farooq A, Guermazi A. Intra- and interrater reliability of three different MRI grading and classification systems after acute hamstring injuries. Eur J Radiol. 2017 Apr;89:182–190. doi: 10.1016/j.ejrad.2017.02.010. Epub 2017 Feb 11.

Wangensteen A, Almusa E, Boukarroum S, Farooq A, Hamilton B, Whiteley R, Bahr R, Tol JL. MRI does not add value over and above patient history and clinical examination in predicting time to return to sport after acute hamstring injuries: a prospective cohort of 180 male athletes. Br J Sports Med. 2015 Dec;49(24):1579–87. doi: 10.1136/bjsports-2015-094892. Epub 2015 Aug 24.


• prospective

• observational, prognostic

• performed at one institution

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Wangensteen, A., Guermazi, A., Tol, J.L. et al. New MRI muscle classification systems and associations with return to sport after acute hamstring injuries: a prospective study. Eur Radiol 28, 3532–3541 (2018).

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  • Hamstring injury
  • Magnetic resonance imaging
  • Radiological grading
  • Classification
  • Return to sport