Location of Hamstring Injuries Based on Magnetic Resonance Imaging: A Systematic Review

Context: Hamstring muscle injury location using magnetic resonance imaging (MRI) is not so well described in the literature. Objective: To describe the location of hamstring injuries using MRI. Data Sources: PubMed, Web of Science, Scopus, SPORTDiscus, Cochrane Library. Study Selection: The full text of studies, in English, had to be available. Case reports and reviews were excluded. Included studies must report the location of hamstring injuries using MRI within 8 days of the acute injury. Study Design: Systematic review. Level of Evidence: Level 4. Data Extraction: A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria. Results: From the 2788 references initially found in 5 databases, we included 34 studies, reporting a total of 2761 acute hamstring injuries. The most frequent muscle head involved was the long head of the biceps femoris (BFLH) (70%), followed by the semitendinosus (ST) (15%), generally associated with BFLH. The most frequent tissue affected was the myotendinous junction (MTJ) accounting for half the cases (52%). Among all lesions, the distribution between proximal, central, and distal lesions looked homogenous, with 34.0%, 33.4% and 32.6%, respectively. The stretching mechanism, while only reported in 2 articles, represented 3% of all reported mechanisms, appears responsible for a specific lesion involving the proximal tendon of the semimembranosus (SM), and leading to a longer time out from sport. Conclusion: BFLH was the most often affected hamstring injuries and MTJ was the most affected tissue. In addition, the distal, central, and proximal locations were homogeneously distributed. We also noted that MRI descriptions of hamstring injuries are often poor and did not take full advantage of the MRI strengths. Systematic Review Registration: Before study initiation, the study was registered in the PROSPERO International prospective register of systematic reviews (registration number CRD42018107580).