Infrapatellar fat pad size, but not patellar alignment, is associated with patellar tendinopathy

Authors

  • A. G. Culvenor,

    1. School of Physiotherapy, Faculty of Health Sciences, La Trobe University, Melbourne, Victoria, Australia
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  • J. L. Cook,

    1. Department of Physiotherapy, School of Primary Health Care, Monash University, Melbourne, Victoria, Australia
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  • S. J. Warden,

    1. Center for Translational Musculoskeletal Research, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, Indiana, USA
    2. Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, Indiana, USA
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  • K. M. Crossley

    1. Department of Mechanical Engineering, Melbourne School of Engineering, The University of Melbourne, Parkville, Victoria, Australia
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Corresponding author: Kay M. Crossley, PhD, Post Grad Dip (Research), BAppSc (Physio), Department of Mechanical Engineering, Melbourne School of Engineering, The University of Melbourne, Parkville 3010, Victoria, Australia. Tel: +61 3 8344 8646, Fax: +61 3 8344 4290, E-mail: k.crossley@unimelb.edu.au

Abstract

Patellar tendinopathy (PT) is one of the most common overuse injuries of the knee. Recent reports indicate that increased body mass is frequently associated with tendinopathy, not only biomechanically but biochemically. Abnormalities of other structures within the knee extensor mechanism [patellofemoral joint (PFJ) alignment and patellar tendon length] that can directly influence the strain distribution of the patellar tendon are inconsistently implicated in PT. The aim of this study was to compare the infrapatellar fat pad volume, patellar tendon length and PFJ alignment in people with chronic PT and a group of age-, gender-, height-, and activity-matched controls with normal tendons. Axial magnetic resonance (MR) images, from 26 participants with PT and 28 control participants were obtained. Fat pad size, patellar tendon length and PFJ alignment were measured digitally from the MR images, using measurement software, and the results compared between the PT group and control group. People with PT had a significantly larger fat pad than healthy controls when controlled for height (P=0.04). Patellar tendon length was not significantly different between groups (P=0.16), nor were there between-group differences for the measures of PFJ alignment (P=0.07–0.76). Thus, the infrapatellar fat pad may play an important role in PT.

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