title: Scheuermann kyphosis: the importance of tight hamstrings in the surgical correction.
abstract: METHODS
  A historic cohort study of the sagittal alignment in 33 consecutive patients with surgically corrected thoracic Scheuermann kyphosis.
  
  
  OBJECTIVE
  To determine if postsurgical imbalance, sagittal malalignment, and decreased lumbar-pelvic range of motion in patients with thoracic Scheuermann kyphosis is related to tight hamstrings.
  
  
  BACKGROUND
  Tight hamstrings are a frequent sign in Scheuermann kyphosis. The importance of tight hamstrings in the surgical management of Scheuermann kyphosis has not yet been studied.
  
  
  METHODS
  Thirty-three patients with Scheuermann kyphosis were managed by surgical correction and fusion. Tight hamstrings, lumbar-pelvic range of motion, and sagittal balance were evaluated. Sixteen patients had tight hamstrings, and 17 patients had nontight hamstrings. Hamstrings were considered tight if the popliteal angle was >30 degrees.
  
  
  RESULTS
  Patients with tight hamstrings have a significantly greater risk of postoperative imbalance (P = 0.05), and these patients can only compensate for this risk by reducing their lumbar lordosis (P = 0.0227). Furthermore, the limitations in the lumbar and pelvic range of motion are predicted by tight hamstrings (P <or= 0.005).
  
  
  CONCLUSIONS
  Tight hamstrings can be considered as an important factor in the surgical management of thoracic Scheuermann kyphosis. Tight hamstring patients can be classified as "lumbar compensators" and as such are prone to overcorrection and imbalance. Preoperative assessment of the lumbar-pelvic range of motion and tight hamstrings should therefore be advised. Extensive fusion of the lumbar segments might compromise the lumbar compensation mechanism and induces further risk of imbalance.
authors.affiliation: Department of Orthopedics, Sint Maartenskliniek, Nijmegen, The Netherlands. ajfhosman@planet.nl
authors.forename: Allard J
authors.initials: AJ
authors.lastname: Hosman
authors.forename: Marinus
authors.initials: M
authors.lastname: de Kleuver
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Anderson
authors.forename: Jacques
authors.initials: J
authors.lastname: van Limbeek
authors.forename: Danielle D
authors.initials: DD
authors.lastname: Langeloo
authors.forename: René P
authors.initials: RP
authors.lastname: Veth
authors.forename: Gerard H
authors.initials: GH
authors.lastname: Slot
mesh_terms: D000328:Adult; D015331:Cohort Studies; D006801:Humans; D007717:Knee; D007738:Kyphosis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008297:Male; D009068:Movement; D010388:Pelvis / Q000503:physiopathology; D011859:Radiography; D013710:Tendons / Q000503:physiopathology*