Acute hamstring injuries : diagnosis and prognosis

Abstract

Introduction: Acute hamstring injury is one of the most common non-contact muscle injuries in sports. The incidence remains high, causing a significant loss of time from training and competition, and a substantial risk of sustaining a reinjury. However, there is still a lack of knowledge and consensus regarding the diagnosis and prognosis for time to return to sport (RTS). The overall aim of this thesis was therefore to investigate aspects related to diagnosis and prognosis of acute hamstring injuries in male athletes, based on baseline clinical examinations and magnetic resonance imaging (MRI).

Methods: This thesis is based on two separate study projects. Male athletes (18-50 years) with acute hamstring injury were recruited in the outpatient department at the study center and underwent standardised baseline clinical and MRI examinations. The MRIs were scored by one or two experienced radiologists using standardised scoring forms. In the first project (Paper I), athletes with positive MRI ≤1 day after injury were prospectively included (between January 2014 and December 2015), and consecutive MRIs were then obtained daily throughout the subsequent week. One radiologist scored the MRIs in order to describe the day-to-day changes in the extent of the oedema, and to investigate the optimal timing for fiber disruption. The second project (Papers II-V) is a prospective cohort with pooled data from 180 athletes included in a previous randomised controlled trial or an ongoing prospective case series (between January 2011 and June 2014). Clinical examinations and MRI were obtained ≤5 days and the athletes were followed up until RTS. In Paper II, two multiple regression models were created to analyse the predictive value of clinical examinations alone, and the additional value of MRI, for time to RTS (in days). To examine the prognostic value of three different MRI grading and classification systems, the intra- and interrater reliability of the modified Peetrons grading system, the Chan acute muscle injury classification (Chan) and the British Athletics Muscle Injury Classification (BAMIC) was first assessed in 40 selected athletes (Paper III). Then, agreement between each of the MRI systems and their associations with RTS were analysed (Paper IV). In Paper V, athletes with MRI confirmed reinjury ≤365 days after RTS were included. The MRIs of the reinjury were compared with the MRIs of the index injury, to describe and analyse reinjury characteristics.

Main results: For the 12 athletes included, there were no significant day-to-day changes in the extent of oedema for any of the oedema measures. Fibre disruption (tear) present in 5 of the athletes, was detectable from day 1, with small and insignificant changes (Paper I). In the first regression model including only patient history and clinical examination, the final model explained 29% of the total variance in time to RTS. By adding MRI variables, the second final model increased the adjusted R2 values from 0.290 to 0.318. Thus, the additional MRI explained only 2.8 % of the variance in RTS (Paper II). For the grading and classification systems, we observed ‘substantial’ to ‘almost perfect’ intra- and interrater reliability for severity gradings, overall anatomical sites and overall classifications for the three MRI systems (Paper III). Among all athletes included in paper IV (n=176), there was for the MRI-positive injuries moderate agreement between the severity gradings. Substantial variance in RTS within and overlap between the MRI categories was demonstrated. Mean differences showed overall main effect for severity gradings, but varied for anatomical sites for Chan and BAMIC. The total variance in RTS explained varied from 7.6% - 11.9% for severity gradings and BAMIC anatomical site. In the 19 athletes included with a reinjury (Paper V), 79% of these reinjuries occurred in the same location within the muscle as the index injury. More than 50% of the reinjuries occurred within 25 days after RTS from the index injury and 50% occurred within 50 days after the index injury. All reinjuries with more severe radiological grading occurred in the same location as the index injury.

Conclusions: Based on the findings, MRI can be performed on any day during the first week following acute hamstring muscle injury with equivalent findings. Regarding prognosis, there were wide individual variations in RTS. The additional predictive value of MRI for time to RTS was negligible compared to baseline patient history taking and clinical examinations alone, and the MRI systems poorly explained the large variance in RTS for MRI-positive injuries. Thus, our findings suggest that baseline clinical or MRI examinations cannot be used to predict RTS just after an acute hamstring injury, and provides no rationale for routine MRI. If used, the specific MRI system should be reported, to avoid miscommunication or misinterpretation in daily clinical practice. The majority of the reinjuries occurred in the same location as the index injury, relatively early after RTS and with a radiologically greater extent. Specific exercise programs focusing on reinjury prevention initiated after RTS from the index injury are therefore highly recommended.

Paper I: Wangensteen A, Bahr R, Van Linschoten R, Almusa E, Whiteley R, Witvrouw E, Tol JL. MRI appearance does not change in the first 7 days after acute hamstring injury - a prospective study. 2017 Jul;51(14):1087-1092. doi: 10.1136/bjsports-2016-096881. Epub 2016 Dec 28.

Paper II: 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.

Paper III: 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: 0.1016/j.ejrad.2017.02.010. Epub 2017 Feb 11.

Paper IV: Wangensteen A, Guermazi A, Tol JL, Roemer FW, Hamilton B, Alonso JM, Whiteley R, Bahr R. New MRI muscle classification systems and associations with return to sport after acute hamstring injuries. European Radiol. 2018. Published online 19 February 2018.

Paper V: Wangensteen A, Tol JL, Witvrouw E, Van Linschoten R, Almusa E, Hamilton B, Bahr R. Hamstring Reinjuries Occur at the Same Location and Early After Return to Sport: A Descriptive Study of MRI-Confirmed Reinjuries. Am J Sports Med. 2016 Aug;44(8):2112-21. doi: 10.1177/0363546516646086. Epub 2016 May 16.