Stiffness of the healing human Achilles tendon

57 Pages·2013·3.26 MB·English

by  Thorsten Schepull

Linköping University Medical Dissertations
No. 1356

Stiffness of the healing human Achilles tendon

Thorsten Schepull

Orthopaedic Surgery
Department of Clinical and Experimental Medicine
Faculty of Health Sciences
Linköping University
Sweden

Linköping 2013
© Thorsten Schepull 2013
Cover picture by Per Aspenberg.

Published papers are reprinted with permission of the publisher.

Printed by LIU-Tryck, Linköping, Sweden 2013

ISBN 978-91-7519-674-9
ISSN 0345-0082
Für Susanne

Table of Contents

1 List of studies…………………………………………………………………………… 9
2 Abstract…………………………………………………………………………………. 11
3 Populärvetenskaplig sammanfattning (summary in Swedish)………………………...... 13
4 Introduction……………………………………………………………………………... 15
4.1 Review of the literature…………………………………………………………… 15
4.1.1 Surgical or non-surgical treatment………………………………………….. 15
4.1.2 Tendon healing and platelet-rich plasma…………………………………… 18
4.1.3 Early loading………………………………………………………………... 19
4.2 Mechanical properties…………………………………………………………….. 22
4.2.1 Deformation………………………………………………………………… 22
4.2.2 Stiffness……………………………………………………………………... 22
4.2.3 Strain………………………………………………………………………... 22
4.2.4 Modulus of elasticity………………………………………………………... 22
4.3 Radiologic evaluation…………………………………………………………….. 22
4.3.1 Radiostereophotogrammetric Analysis (RSA)……………………………... 22
4.3.2 Computed tomography (CT)……………………………………………...… 23
5 Aims, with background in brief………………………………………………………… 24
6 Methods…………………………………………………………………………………. 25
6.1 Surgical and non-surgical treatment……………………………………………… 25
6.1.1 Surgical treatment…………………………………………………..………. 25
6.1.2 Non-surgical treatment…………………...…………………………………. 26
6.1.3 Platelet-rich plasma – preparation and injection……………………………. 27
6.2 Postoperative treatment…………………………………………………………… 28
6.3 Rehabilitation……………………………………………………………………... 30
6.4 Radiologic measurements………………………………………………………… 30
6.4.1 Radiostereophotogrammetric Analysis…….……………………………… 30
6.4.2 CT and Ultrasound………………………………………………………….. 32
6.5 Functional outcome……………………………………………………………….. 35
6.5.1 Heel-Raise index……………………………………………………………. 36
6.5.2 Achilles tendon Total Rupture Score……………………………………….. 36
7 Results in brief………………………………………………………………………….. 38
A pilot study to find a method to measure mechanical properties of the healing
human Achilles tendon…
….showing no difference between surgical and conservative treatment, but a greater
variation in conservative treatment results…
….and platelet injection did not improve mechanical properties….
….but tensile loading did improve…
….and radiodensity reflected the mechanical properties.
8 Discussion………………………………………………………………………………. 40
9 Conclusions……………………………………………………………………………... 48
10 Future research………………………………………………………………………… 49
11 Acknowledgements……………………………………………………………………. 50
12 References……………………………………………………………………………... 52
13 Appendix...…………………………………………………………………………….. 59
14 Papers I-V……………………………………………………………………………... 61

1 List of studies

I
Mechanical properties during healing of Achilles tendon ruptures to predict final outcome: a
pilot Roentgen stereophotogrammetric analysis in 10 patients.
Schepull T, Kvist J, Andersson C, Aspenberg P.
BMC Musculoskelet Disord. 2007 Nov 26;8:116.

II
Early E-modulus of healing Achilles tendons correlates with late function: similar results with
or without surgery.
Schepull T, Kvist J, Aspenberg P.
Scand J Med Sci Sports. 2012 Feb;22(1):18-23

III
Autologous platelets have no effect on the healing of human Achilles tendon ruptures: a
randomized single-blind study.
Schepull T, Kvist J, Norrman H, Trinks M, Berlin G, Aspenberg P.
Am J Sports Med. 2011 Jan;39(1):38-47

IV
Early, controlled tension improves the material properties of healing human Achilles tendons
after rupture: a randomized trial.
Schepull T, Aspenberg P
Submitted manuscript

V
Healing of human Achilles tendon rupture: Radiodensity reflects mechanical properties.
Schepull T, Aspenberg P
Submitted manuscript
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2 Abstract

Achilles tendon ruptures in humans are followed by a long period of immobilisation,
rehabilitation and limitations of physical activity and sometimes work also. This prolonged
period probably leaves a marginal for improvement in the management of this injury. Animal
studies have shown that there are several possibilities to influence and improve tendon
healing.

The aim of this thesis was to find a way to examine the mechanical properties of the healing
human Achilles tendon and, by using that method, to gain a better understanding of the tissue
properties and healing process in these tendons. It was also our aim to use our knowledge
from animal studies in an attempt to improve tendon healing in humans.

We developed a radiological method using radiostereophotogrammetric analysis (RSA) and
computed tomography (CT), which enabled us to measure the stiffness of the healing Achilles
tendon. The results of these measurements, as early as 7 weeks after injury correlated with the
late clinical results in all studies. Clinical results were measured using a heel-raise test
comparing the injured with the non-injured tendon. We could not find a significant difference
in stiffness between patients treated surgically or non-surgically. Neither could we
demonstrate that platelet-rich plasma improved the mechanical properties of the healing
tendon or the clinical outcome, within the limits of the statistical power. In contrast, patients
following a specific training programme with early tension loading of the tendon twice a day
developed stiffer tendon tissue later in the healing process.

Since RSA is unsuitable for routine clinical use, we evaluated the possibility to use
radiodensity findings from CT as a proxy for healing and its correlation to mechanical and
clinical results. Density and mechanical properties correlated strongly when analysing all time
points together, but only weakly at each particular point in time. Density may still be useful in
describing mechanical properties at a later stage of repair, but this remains to be seen.

In conclusion, these studies show that early mechanical properties correlate to late clinical
outcome and that the early use of daily tension loading sessions leads to an improvement in
the mechanical properties of the tendon tissue.

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