title: Normal clinical and ultrasound findings indicate a low risk to sustain jumper's knee patellar tendinopathy: a longitudinal study on Swedish elite junior volleyball players.
abstract: BACKGROUND
  Jumper's knee patellar tendinopathy is well known to be a common and difficult injury in volleyball. Knowledge about its aetiology and pathogenesis is sparse.
  
  
  OBJECTIVE
  To prospectively follow clinical status, tendon structure and vascularity in elite junior volleyball players.
  
  
  METHODS
  22 volleyball players (44 patellar tendons) beginning their first grade at the Swedish National Centre for high school volleyball were continuously evaluated clinically and by ultrasonography (US) and power Doppler (PD) over the 3 school years.
  
  
  RESULTS
  At inclusion, there were 44 tendons being assessed. Jumper's knee was diagnosed clinically in eight patellar tendons (seven of eight had structural changes and vascularity on US+PD). There were 27 normal (clinical and US+PD) tendons. At 3 years, there were 36 tendons still being assessed. Four individuals (eight tendons) had been excluded. Jumper's knee had developed in 2 of 25 (2 were excluded) tendons that were normal (clinical and US+PD) at inclusion. Jumper's knee (clinical and US+PD) was also present in six tendons.
  
  
  CONCLUSIONS
  Normal clinical tests and ultrasound findings at the start indicated a low risk for these elite junior volleyball players to sustain jumper's knee during three school years with intensive training and playing.
authors.affiliation: Department of Surgical and Perioperative Science, Sports Medicine, Umeå University, Umeå, Sweden. kalle.gisslen@vgregion.se
authors.forename: Karl
authors.initials: K
authors.lastname: Gisslén
authors.forename: Csaba
authors.initials: C
authors.lastname: Gyulai
authors.forename: Peter
authors.initials: P
authors.lastname: Nordström
authors.forename: Håkan
authors.initials: H
authors.lastname: Alfredson
mesh_terms: D000293:Adolescent; D000328:Adult; D001265:Athletic Injuries / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010329:Patella / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D012307:Risk Factors; D013177:Sports; D013548:Sweden; D052256:Tendinopathy / Q000000981:diagnostic imaging*; D014463:Ultrasonography