title: Ultrasound strain mapping of Achilles tendon compressive strain patterns during dorsiflexion.
abstract: Heel lifts are commonly prescribed to patients with Achilles tendinopathy, yet little is known about the effect on tendon compressive strain. The purposes of the current study were to (1) develop a valid and reliable ultrasound elastography technique and algorithm to measure compressive strain of human Achilles tendon in vivo, (2) examine the effects of ankle dorsiflexion (lowering via controlled removal of a heel lift and partial squat) on compressive strain of the Achilles tendon insertion and (3) examine the relative compressive strain between the deep and superficial regions of the Achilles tendon insertion. All tasks started in a position equivalent to standing with a 30mm heel lift. An ultrasound transducer positioned over the Achilles tendon insertion was used to capture radiofrequency images. A non-rigid image registration-based algorithm was used to estimate compressive strain of the tendon, which was divided into 2 regions (superficial, deep). The bland-Altman test and intraclass correlation coefficient were used to test validity and reliability. One-way repeated measures ANOVA was used to compare compressive strain between regions and across tasks. Compressive strain was accurately and reliably (ICC>0.75) quantified. There was greater compressive strain during the combined task of lowering and partial squat compared to the lowering (P=.001) and partial squat (P<.001) tasks separately. There was greater compressive strain in the deep region of the tendon compared to the superficial for all tasks (P=.001). While these findings need to be examined in a pathological population, heel lifts may reduce tendon compressive strain during daily activities.
authors.affiliation: University of Iowa, Department of Physical Therapy and Rehabilitation Science, United States. Electronic address: ruthchimenti@gmail.com.
authors.forename: Ruth L
authors.initials: RL
authors.lastname: Chimenti
authors.affiliation: University of Rochester, Department of Orthopaedic Surgery, United States.
authors.forename: A Samuel
authors.initials: AS
authors.lastname: Flemister
authors.affiliation: University of Rochester, Department of Orthopaedic Surgery, United States.
authors.forename: John
authors.initials: J
authors.lastname: Ketz
authors.affiliation: University of Rochester, Department of Biomedical Engineering, United States.
authors.forename: Mary
authors.initials: M
authors.lastname: Bucklin
authors.affiliation: University of Rochester, Department of Biomedical Engineering, United States.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Buckley
authors.affiliation: University of Rochester, Department of Surgery, United States.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Richards
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D019245:Compressive Strength; D054459:Elasticity Imaging Techniques; D005260:Female; D006365:Heel; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011187:Posture; D015203:Reproducibility of Results; D013180:Sprains and Strains / Q000473:pathology; D013708:Tendon Injuries / Q000473:pathology; D013710:Tendons / Q000502:physiology; D055815:Young Adult
keywords: Achilles tendinopathy; Heel lift; Tendon strain; Ultrasound elastography