title: Changes in morphological and elastic properties of patellar tendon in athletes with unilateral patellar tendinopathy and their relationships with pain and functional disability.
abstract: Patellar tendinopathy (PT) is one of the most common knee disorders among athletes. Changes in morphology and elasticity of the painful tendon and how these relate to the self-perceived pain and dysfunction remain unclear.
  
  
  
  To compare the morphology and elastic properties of patellar tendons between athlete with and without unilateral PT and to examine its association with self-perceived pain and dysfunction.
  
  
  
  In this cross-sectional study, 33 male athletes (20 healthy and 13 with unilateral PT) were enrolled. The morphology and elastic properties of the patellar tendon were assessed by the grey and elastography mode of supersonic shear imaging (SSI) technique while the intensity of pressure pain, self-perceived pain and dysfunction were quantified with a 10-lb force to the most painful site and the Victorian Institute of Sport Assessment-patella (VISA-P) questionnaire, respectively.
  
  
  
  In athletes with unilateral PT, the painful tendons had higher shear elastic modulus (SEM) and larger tendon than the non-painful side (p<0.05) or the dominant side of the healthy athletes (p<0.05). Significant correlations were found between tendon SEM ratio (SEM of painful over non-painful tendon) and the intensity of pressure pain (rho  = 0.62; p = 0.024), VISA-P scores (rho  = -0.61; p = 0.026), and the sub-scores of the VISA-P scores on going down stairs, lunge, single leg hopping and squatting (rho ranged from -0.63 to -0.67; p<0.05).
  
  
  
  Athletes with unilateral PT had stiffer and larger tendon on the painful side than the non-painful side and the dominant side of healthy athletes. No significant differences on the patellar tendon morphology and elastic properties were detected between the dominant and non-dominant knees of the healthy control. The ratio of the SEM of painful to non-painful sides was associated with pain and dysfunction among athletes with unilateral PT.
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong; Guangdong-Hongkong Joint Sports Rehabilitation and Research Center, Guangdong Provincial Work Injury Rehabilitation Hospital, Guangzhou, China.
authors.forename: Zhi Jie
authors.initials: ZJ
authors.lastname: Zhang
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Gabriel Yin-fat
authors.initials: GY
authors.lastname: Ng
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Wai Chun
authors.initials: WC
authors.lastname: Lee
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Siu Ngor
authors.initials: SN
authors.lastname: Fu
mesh_terms: D000293:Adolescent; D000328:Adult; D056352:Athletes; D003430:Cross-Sectional Studies; D006801:Humans; D008297:Male; D010146:Pain / Q000150:complications; D017847:Patellar Ligament / Q000473:pathology* / Q000503:physiopathology; D052256:Tendinopathy / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D055815:Young Adult