title: Low range of ankle dorsiflexion predisposes for patellar tendinopathy in junior elite basketball players: a 1-year prospective study.
abstract: BACKGROUND
  Patellar tendinopathy (PT) is one of the most common reasons for sport-induced pain of the knee. Low ankle dorsiflexion range might predispose for PT because of load-bearing compensation in the patellar tendon.
  
  
  OBJECTIVE
  The purpose of this 1-year prospective study was to analyze if a low ankle dorsiflexion range increases the risk of developing PT for basketball players.
  
  
  METHODS
  Cohort study (prognosis); Level of evidence, 2.
  
  
  METHODS
  Ninety junior elite basketball players were examined for different characteristics and potential risk factors for PT, including ankle dorsiflexion range in the dominant and nondominant leg. Data were collected over a 1-year period and follow-up, including reexamination, was made at the end of the year.
  
  
  RESULTS
  Seventy-five players met the inclusion criteria. At the follow-up, 12 players (16.0%) had developed unilateral PT. These players were found to have had a significantly lower mean ankle dorsiflexion range at baseline than the healthy players, with a mean difference of -4.7° (P = .038) for the dominant limb and -5.1° (P = .024) for the nondominant limb. Complementary statistical analysis showed that players with dorsiflexion range less than 36.5° had a risk of 18.5% to 29.4% of developing PT within a year, as compared with 1.8% to 2.1% for players with dorsiflexion range greater than 36.5°. Limbs with a history of 2 or more ankle sprains had a slightly less mean ankle dorsiflexion range compared to those with 0 or 1 sprain (mean difference, -1.5° to -2.5°), although this was only statistically significant for nondominant legs.
  
  
  CONCLUSIONS
  This study clearly shows that low ankle dorsiflexion range is a risk factor for developing PT in basketball players. In the studied material, an ankle dorsiflexion range of 36.5° was found to be the most appropriate cutoff point for prognostic screening. This might be useful information in identifying at-risk individuals in basketball teams and enabling preventive actions. A history of ankle sprains might contribute to reduced ankle dorsiflexion range.
authors.affiliation: Department of Integrative Medical Biology, Anatomy, Umeå University, Sweden. ludvig.backman@anatomy.umu.se
authors.forename: Ludvig J
authors.initials: LJ
authors.lastname: Backman
authors.forename: Patrik
authors.initials: P
authors.lastname: Danielson
mesh_terms: D000293:Adolescent; D000843:Ankle Joint / Q000502:physiology*; D001490:Basketball / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D017847:Patellar Ligament / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors; D013180:Sprains and Strains / Q000150:complications / Q000503:physiopathology; D052256:Tendinopathy / Q000209:etiology*; D055815:Young Adult