title: Hamstring Reinjuries Occur at the Same Location and Early After Return to Sport: A Descriptive Study of MRI-Confirmed Reinjuries.
abstract: Despite relatively high reinjury rates after acute hamstring injuries, there is a lack of detailed knowledge about where and when hamstring reinjuries occur, and studies including imaging-confirmed reinjuries are scarce.
  
  
  
  To investigate the location, radiological severity, and timing of reinjuries on magnetic resonance imaging (MRI) compared with the index injury.
  
  
  
  Case series; Level of evidence, 4.
  
  
  
  A MRI scan was obtained ≤5 days after an acute hamstring index injury in 180 athletes, and time to return to sport (RTS) was registered. Athletes with an MRI-confirmed reinjury in the same leg ≤365 days after RTS were included. Categorical grading and standardized MRI parameters of the index injury and reinjury were scored by a single radiologist (with excellent intraobserver reliability). To determine the location of the reinjury, axial and coronal views of the index injury and reinjury were directly compared on proton density-weighted fat-suppressed images.
  
  
  
  In the 19 athletes included with reinjury, 79% of these reinjuries occurred in the same location within the muscle as the index injury. The median time to RTS after the index injury was 19 days (range, 5-37 days; interquartile range [IQR], 15 days). The median time between the index injury and reinjury was 60 days (range, 20-316 days; IQR, 131 days) and the median time between RTS after the index injury and the reinjury was 24 days (range, 4-311 days; IQR, 140 days). More than 50% of reinjuries occurred within 25 days (4 weeks) 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.
  
  
  
  The majority of the hamstring reinjuries occurred in the same location as the index injury, early after RTS and with a radiologically greater extent, suggesting incomplete biological and/or functional healing of the index injury. Specific exercise programs focusing on reinjury prevention initiated after RTS from the index injury are highly recommended.
authors.affiliation: Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar Oslo Sports Trauma Research Center, Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway arnlaug.wangensteen@aspetar.com.
authors.forename: Arnlaug
authors.initials: A
authors.lastname: Wangensteen
authors.affiliation: Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar Amsterdam Center for Evidence Based Medicine, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Tol
authors.affiliation: Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar Department Rehabilitation Science and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Witvrouw
authors.affiliation: Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Robbart
authors.initials: R
authors.lastname: Van Linschoten
authors.affiliation: Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Emad
authors.initials: E
authors.lastname: Almusa
authors.affiliation: Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar High Performance Sport NZ, Sport Research Institute of New Zealand, Millennium Institute of Sport and Health, Mairangi Bay, Auckland, New Zealand.
authors.forename: Bruce
authors.initials: B
authors.lastname: Hamilton
authors.affiliation: Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar Oslo Sports Trauma Research Center, Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Roald
authors.initials: R
authors.lastname: Bahr
mesh_terms: D000293:Adolescent; D000328:Adult; D001265:Athletic Injuries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000070633:Hamstring Muscles / Q000000981:diagnostic imaging* / Q000293:injuries*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D015203:Reproducibility of Results; D000068958:Return to Sport; D013997:Time Factors; D014945:Wound Healing; D055815:Young Adult
keywords: hamstring injury; location; magnetic resonance imaging; reinjury; return to sport