title: Time to return to full training is delayed and recurrence rate is higher in intratendinous ('c') acute hamstring injury in elite track and field athletes: clinical application of the British Athletics Muscle Injury Classification.
abstract: BACKGROUND
  The British Athletics Muscle Injury Classification describes acute muscle injuries and their anatomical site within muscle based on MRI parameters of injury extent. It grades injuries from 0 to 4 and classifies location based on a myofascial (a), musculotendinous (b) or intratendinous (c) description. This is a retrospective cohort study that assessed time to return to full training (TRFT) and injury recurrence in the different British Athletics classifications for hamstring injuries sustained by elite track and field (T&F) athletes over a 4-year period.
  
  
  METHODS
  The electronic medical records (EMRs) of 230 elite British T&F athletes were reviewed. Athletes who sustained an acute hamstring injury, with MRI investigation within 7 days of injury, were included. MRI were graded by two musculoskeletal radiologists using the British Athletics Muscle Injury Classification. The EMRs were reviewed by 2 sports physicians, blinded to the new classification; TRFT and injury recurrence were recorded.
  
  
  RESULTS
  There were 65 hamstring injuries in 44 athletes (24±4.4 years; 28 male, 16 female). TRFT differed among grades (p<0.001). Grade 3 injuries and 'c' injuries took significantly longer and grade 0 injuries took less TRFT. There were 12 re-injuries; the injury recurrence rate was significantly higher in intratendinous (c) injuries (p<0.001). There was no difference in re-injury rate between number grades 1-3, hamstring muscle affected, location (proximal vs central vs distal), age or sex.
  
  
  CONCLUSIONS
  This study describes the clinical application of the British Athletics Muscle Injury Classification. Different categories of hamstring injuries had different TRFT and recurrence rate. Hamstring injuries that extend into the tendon ('c') are more prone to re-injury and delay TRFT.
authors.affiliation: British Athletics Medical Team, Hospital of St John & St Elizabeth, London, UK.
authors.forename: Noel
authors.initials: N
authors.lastname: Pollock
authors.affiliation: Radiology Department, Royal Orthopaedic Hospital, Birmingham, UK.
authors.forename: Anish
authors.initials: A
authors.lastname: Patel
authors.affiliation: Bristol Royal Infirmary, University Hospitals of Bristol, UK.
authors.forename: Julian
authors.initials: J
authors.lastname: Chakraverty
authors.affiliation: Research and Development Department, Royal Orthopaedic Hospital Foundation Trust, Birmingham, UK.
authors.forename: Anu
authors.initials: A
authors.lastname: Suokas
authors.affiliation: Radiology Department, Royal Orthopaedic Hospital, Birmingham, UK.
authors.forename: Stephen L J
authors.initials: SL
authors.lastname: James
authors.affiliation: British Athletics Medical Team, Loughborough National Performance Institute, Loughborough, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Chakraverty
mesh_terms: D000293:Adolescent; D000328:Adult; D056352:Athletes; D001265:Athletic Injuries / Q000145:classification*; D005260:Female; D006801:Humans; D007869:Leg Injuries / Q000145:classification*; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries*; D020127:Recovery of Function; D012008:Recurrence; D012189:Retrospective Studies; D000068958:Return to Sport; D017695:Soft Tissue Injuries / Q000145:classification* / Q000175:diagnosis; D013997:Time Factors; D014142:Track and Field; D006113:United Kingdom; D055815:Young Adult
keywords: Hamstring; Injury; Muscle; Tendon