In vivo evaluation of patellar tendon stiffness in individuals with patellofemoral pain syndrome

Article type: Research Article

Authors: Liu, Hsin-Yi^{; ;} | Boling, Michelle | Padua, Darin | Creighton, R. Alexander | Weinhold, Paul^;

Affiliations: Department of Orthopaedics, University of North Carolina, Chapel Hill, NC 27599, USA | Sports Medicine Laboratory, University of North Carolina, Chapel Hill, NC 27599, USA | Department of Physical Education and Recreation, North Carolina Central University, Durham, NC27707, USA

Note: [] Corresponding author. Email: hliu@nccu.edu

Abstract: The objective of this study was to utilise an ultrasonic technique to assess the effect of patellofemoral pain syndrome (PFPS) on the mechanical properties of the patellar tendon. Seven subjects with PFPS and seven matched control subjects volunteered to participate in this study. Subjects were asked to perform isometric maximal voluntary contractions of the knee extensors while their knee extension torque was monitored and the displacement of the patellar tendon was recorded with an ultrasonic system. Our results showed significantly lower tendon stiffness (by ˜30%) in the PFPS subjects. Although tendon secant modulus was lower by 34% in the PFPS subjects, the difference was not statistically significant. Therefore, we conclude that the ultrasonic technique was able to detect a decrease in the structural stiffness of the patellar tendon associated with PFPS. The decrease in tendon stiffness was moderately correlated with the length of symptoms in these individuals.

Keywords: tendon mechanical properties, ultrasound measurement, anterior knee pain, tendon elastic modulus, chondromalacia patella, knee joint loading

DOI: 10.1080/11762320802604741

Journal: Applied Bionics and Biomechanics, vol. 5, no. 2, pp. 59-63, 2008