Feasibility of an Early Progressive Strength Exercise Programme for Acute Achilles Tendon Rupture
Phase: NA
Conditions: Achilles Tendon Rupture
Sponsor: Aalborg University Hospital

Protocol_Feasibility_ver 1.0 
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The Achilles tendon back on track. 
Feasibility of an early progressive strength 
exercise programme for acute Achilles 
tendon rupture. 
 
 
 
Protocol version 1.0 
29.Sept 2019 
 
 

Protocol_Feasibility_ver 1.0 
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Protocol  
Administrative information  
1.Title  
Feasibility of an early progressive strength exercise programme for acute Achilles tendon rupture. 
 
2.Trial registration  
2a The study will be registered at ClinicalTrials.gov: nr and date 
2b WHO Trial Registration Data Set 
Data category 
Information 
Primary registry and trial identifying number 
Clinical Trials 
Date of registration in primary registry 
19.Sept 2019 
Secondary identifying numbers 
Ethics Committee N-20180072 
Source(s) of monetary or material support 
Physiotherapy and Occupational therapy, Aalborg 
University Hospital 
Primary sponsor 
Physiotherapy and Occupational therapy, Aalborg 
University Hospital 
Secondary sponsor(s) 
Orthopaedic department, Aalborg University Hospital 
Contact for public queries 
mc@rn.dk 
Contact for scientific queries 
mc@rn.dk  
Public title 
The Achilles tendon back on track. Feasibility of an early 
progressive strength exercise programme for acute 
Achilles tendon rupture. 
Scientific title 
Feasibility of an early progressive strength exercise 
programme for acute Achilles tendon rupture. 
Countries of recruitment 
Denmark 
Health condition(s) or problem(s) studied 
Achilles tendon rupture 
Intervention(s) 
Early progressive strength exercise programme 
Key inclusion and exclusion criteria 
Inclusion criteria: Patients with acute Achilles tendon 
rupture treated non-surgically. Diagnosed and treatment 
initiated within 3 days (of their injury). Age 18 - 65, able 
and willing to participate in the intervention. Able to 
speak and understand Danish 
Exclusion criteria: Insertional Achilles tendon rupture on 
calcaneus or rupture in the musculo-tendinous junction 
of the triceps surae. Previous Achilles tendon rupture or 
other conditions in either leg causing lower leg disability 
(pain, deficits in strength or range of movement). Treated 
with Fluorquinolons or Corticosteroids within the last 6 
months. Diabetes. Severe medical illness: ASA score 
higher than or equal to 3 
Study type 
Interventional, feasibility 
Date of first enrollment 
October 2019 
Target sample size 
16 
Recruitment status 
Not yet recruiting 
Primary outcome(s) 
Feasibility: Acceptability and compliance 
Key secondary outcomes 
Fear of re-rupture, ATRS, IPAQ short form, ATRA, 
Achilles tendon properties, delay in start of exercises, 
adverse events, muscle endurance 

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3. Protocol version 
Version 1.0 
 
4. Funding 
The Physiotherapy and Occupational therapy department and Orthopaedic Surgery department at 
Aalborg University Hospital has guaranteed for the funding of the PhD study. This work was also 
supported by the Danish Physiotherapist Research Foundation, North Denmark Region Research 
foundation and AP Møller Lægefonden. 
 
5. Roles and responsibilities. 
5a Names, affiliations, and roles of protocol contributors 
 
Marianne Christensen (MC) 
 
Physiotherapy and Occupational Therapy, Aalborg University Hospital, Hobrovej 18-22, 9000 
Aalborg, Denmark, mc@rn.dk , Phone: +45 97662530 
 
Orthopaedic Research Unit, Aalborg University Hospital, Aalborg, Denmark 
 
Department of Clinical Medicine, Aalborg University, Aalborg, Denmark  
 
Karin Grävare Silbernagel (KGS), Department of Physical Therapy, University of Delaware, DE, USA, 
kgs@udel.edu 
 
Jennifer A. Zellers (JAZ), Program in Physical Therapy, Washington University School of Medicine in 
St. Louis, USA, jzellers@wustl.edu 
 
Michael Skovdal Rathleff (MSR), Physiotherapy and Occupational Therapy, Aalborg University 
Hospital, Hobrovej 18-22, 9000 Aalborg, Denmark, misr@hst.aau.dk 
 
Inge Lunding Kjær (ILK), Orthopaedic Research Unit, Aalborg University Hospital, Hobrovej 18-22, 
9000 Aalborg, Denmark.  i.kjaer@rn.dk 
 
The project will be conducted with MC as primary investigator as part of her Ph.D.-studies. MC and 
MSR wrote the first draft of the protocol. ILK and KGS both made valuable scientific additions to 
the draft. ILK is chief orthopaedic foot surgeon and has the clinical responsibility for the study. 
MSR and KGS provided contribution to the study design, contents of the intervention and the 
evaluation methods. All authors approved the study protocol. 
 
5b Name and contact information for the trial sponsor 
Physiotherapy and Occupational Therapy department, Orthopaedic department,  
Clinic Head- and Orto, 
Aalborg University Hospital 
Hobrovej 18-22 
9000 Aalborg 
Denmark 

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5c Role of study sponsor and funders 
Sponsor is a part of the study, but is not involved in design, planning and analysis of the study. 
Sponsor will collaborate to ensure the right conditions for planning and conduct of the study and the 
publication of the results. Sponsor is non-commercial and declares no conflict of interest. 
The funding sources will have no influence in the design of this study and will not have any role 
during the study execution, interpretation of the data or dissemination of results. 
 
5d Composition, roles, and responsibilities of the coordinating centre, steering committee, 
endpoint adjudication committee, data management team, and other individuals or groups 
overseeing the trial, if applicable (see Item 21a for data monitoring committee) 
N/A 
 
Introduction 
6. Background and rationale 
6a Descriptions of research question 
Acute Achilles tendon rupture is a common injury and in Denmark the incidence has increased in 
recent years from 18.2/100.000 in 1984 and up to 31.17/100.000 in 2013.1,2 Achilles tendon rupture 
usually occurs at age 30-50 with a male to female ratio 3-5:1.1-3 The Achilles tendon is the largest 
and strongest tendon in the human body and is crucial for normal gait and running.4  
Regardless of choice of either surgical or non-surgical treatment, long-term muscular deficits and a 
decreased function after Achilles tendon rupture is found up to 7 and 10 years later.5-7 The majority 
of the patients are of working age and a deficit in physical performance will have impact on 
returning to work and sports.8-10 The risk of not being able to return to work or sport has potential 
influence on patients quality of life, risk of lifestyle diseases and healthcare economics. 
 
Historically surgical treatment has been favoured mainly because the re-rupture rates are lower 
compared to non-surgical treatment (3 vs 13%, respectively).11,12 However, there is a risk of wound 
infection in surgical treatment compared to non-surgical and the results after a deep infection are 
often devastating.13,14  
There has been promising results in treatments using early functional rehabilitation (EFR) during 
the first eight weeks of treatment after both surgical and non-surgical treatment. The re-rupture rate 
after EFR is reported similar to those of surgery, which gives EFR an advantage to the former non-
surgical treatment with immobilisation.13,15-18 The early functional rehabilitation aims at minimizing 
the loss of muscle strength that is inevitable in the immobilizing period. Laboratory studies have 
also indicated that early loading of the ruptured tendon will improve the tendon healing in 
animals19,20 and clinical studies have confirmed this21. 
  
 

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Several studies have reported use of controlled ankle/foot exercises, but few studies examined the 
effect of the exercises on its own and primarily after surgery.22-25 We recently conducted a 
systematic review investigating the EFR used in the first 8 weeks of treatment and it showed very 
heterogeneus intervention protocols. (Zellers et al, accepted)(Christensen et al, in review) The 
components used in the EFR ranges from early weight-bearing and controlled range of motion 
ankle/foot exercises to strength exercises. Also the type of immobilisation varies from using a rigid 
cast to specially designed shoes to mobile walker orthosis. The timing of initiating exercises, 
weight-bearing and changing foot position from equinus to neutral also varies. The majority of the 
published protocols mainly focused on mobilisation of the patient and not including exercises for 
the foot/ankle that would load the Achilles tendon. 
The general descriptions of the exercise programs were lacking important information such as type, 
time of application, frequency, intensity and progression of the exercises. This emphasises the 
problem that exists with the heterogeneous EFR and lack of systematic reviews and clinical 
guidelines that translate result into reproducible exercise protocols.  
 
It is time for optimizing the exercises to address the need for improvement of the muscle strength 
and function, and ensuring that the exercises are well described. 
In the long term the optimal goal is to present a well described new exercise intervention and 
investigate the effect compared to the present treatment in a RCT. When developing a new 
treatment, essential questions about the feasibility of the intervention are not known. It is important 
to know this before embarking on a large scale trial. Even though the RCT has advantages, it often 
demands a lengthy time perspective to include sufficient number of participants and it will all be 
wasted if you in retrospect discover that there are feasibility issues of the intervention.26,27 
Consequently it is reasonable to do a feasibility study of how the patients tolerate a new exercise 
program regarding adherence and willingness to the exercise program. 
 
6b Explanation for choice of comparators 
The purpose of this study is to test the feasibility of the exercise program and it is not the intention 
to replicate the future RCT with both intervention and a comparator. Therefore comparators will not 
be included in the feasibility study. 
 
7. Objectives 
The primary aim is to test the feasibility of an early progressive exercise program for patients with 
Achilles tendon rupture treated non-surgically. Feasibility in this study will be defined as successful 
patient acceptability and compliance of the exercise intervention. It will not include feasibility of 
physiotherapist prescription of the exercises or the feasibility in a health care system perspective. 
Definition of feasibility is described further in section 12. Outcome. 
 
 

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8. Trial design 
This study is designed as a single group, interventional feasibility study. Follow-up after 9 and 13 
weeks. The protocol will follow the SPIRIT statement and the reporting of the study will follow the 
CONSORT 2010 statement, extension to randomised pilot and feasibility trials.28,29 
Week 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
Emergency  department 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Diagnostic and treatment 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Inclusion 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Outpatient Clinic            
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Immobilisation in equinus 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Orthosis + wedges 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Exercise intervention 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Follow-up 
  
  
F 
F 
F 
F 
F 
F 
F 
F 
F 
  
  
  
F 
  
Risk assessment 
  
  
! 
! 
! 
! 
! 
! 
! 
! 
  
  
  
  
  
  
Data analysis 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
D 
 
  
Ordinary patient visits to hospital 
  
Treatment 
  
Feasibility study  
F 
Follow-up 
! 
Risk assessment 
D Data analysis 
 
Methods: Participants, interventions, and outcomes 
9. Study setting 
Participants will be recruited from the emergency Department at Aalborg University Hospital 
Denmark and followed at the Orthopaedic Outpatient Clinic. The intervention will take place at the 
Physiotherapy and Occupational Therapy Department. 
The primary investigator (MC) will be responsible for screening for eligibility, exercise 
intervention, data collection and prevention of adverse events. The primary investigator has more 
than 20 years of experience as a physiotherapist and currently holds a position with diagnostic 
responsibility at the Foot and ankle outpatient clinic. The chief orthopaedic foot surgeon (ILK) has 
the overall responsibility for the clinical treatment and safety. At the joint weekly meeting the 
progression of the study inclusion and treatment is evaluated. 
 
10. Eligibility criteria 
Inclusion criteria: 
- 
Patients with acute total Achilles tendon rupture treated non-surgically 
- 
Diagnosed and treatment initiated within 3 days (of their injury) 

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- 
Age 18 - 65, able and willing to participate in the intervention 
- 
Able to speak and understand Danish 
Exclusion criteria:  
- 
Insertional Achilles tendon rupture on calcaneus or rupture in the musculo-tendinous 
junction of the triceps surae 
- 
Previous Achilles tendon rupture or other conditions in either leg causing lower leg 
disability (pain, deficits in strength or range of movement) 
- 
Treated with Fluorquinolons or Corticosteroids within the last 6 months 
- 
Diabetes  
- 
Severe medical illness: ASA score higher than or equal to 3.30 
Excluded patients and patients not willing to participate will follow the usual program of 
rehabilitation for non-surgical treatment at Aalborg University Hospital. 
 
11. Interventions 
11a Intervention for each group with sufficient detail to allow replication, including how and 
when they will be administered. 
The exercise intervention starts one week after diagnosis at the Emergency Department. There will 
be weekly exercise sessions and daily home program until removal of the walker after nine weeks. 
The exercise intervention aims at facilitating the muscle activity in the beginning of the 
immobilising period and subsequently progress the load to strengthen the muscles within the 
restrictions for the healing tendon. The strength exercises aims at loading the Achilles tendon-
muscle complex as opposed to more general exercises that involves the whole leg. 
To protect the tendon while doing range of motion of the foot, dorsiflexion is restricted beyond 
neutral (0 degrees of dorsiflexion). The load on the strength exercises will progress from isometric 
contraction without external load to strengthening exercises with 10-20 RM. Each strength exercise 
can progress with added weight or stronger elastic band. The Borg scale is used to guide the patient 
to progress or regress the load in each exercise. The recommended level being “easy” to “hard” (2-
5/10). It is emphasized that the exercises must not cause sudden or severe pain in the tendon, but 
muscle soreness is to be expected.  
Progression is performed individually and with a progression of 2-10%. This is generally accepted 
as a reasonable progression in resistance training and for exercise therapy for painful tendinopathy 
and even though specific research on Achilles tendon rupture is lacking is seems a safe precaution 
to prescribe in the early rehabilitation of Achilles tendon rupture.31  
 
New treatment - Strength exercises: 
- 
Isometric contraction of the leg muscles inside the immobilising orthosis. Short time under 
tension (TUT) and load in the beginning and then progression as the patient feels 
comfortable. Progression of load will be allowing to push the forefoot against the bottom of 

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the walker with more pressure. Position: can be seated, standing or lying down with bent or 
straight knee. 
- 
Seated heel-rise with heel on wedges in the walker boot and with open straps to allow 
movement. The wedges under the heel prevents excessive dorsiflexion of the foot. 
Progressing with external weight on the knee. To ensure contraction of the gastrocnemius 
and not just the flexor muscles to the toes, the contraction will be monitored with 
ultrasound. Position: seated with bent knee in 90 degrees and possibly a cushion on the chair 
to compensate for the higher heel in the walker with wedges. 
- 
Resistance strength exercise with elastic band. This exercise is part of the usual treatment, 
but will be started earlier and with progress to a stronger elastic band (from yellow to 
red/green/blue). The patient is instructed to do plantarflexion from neutral position. They are 
not allowed to pull the foot in dorsiflexion beyond neutral foot position. Position: seated 
with bend or straight knee. 
 
General information (as given with current treatment): 
All patients receive general information about Achilles tendon rupture, tendon healing, choice of 
treatment and risks. The long term prognosis of the Achilles tendon rupture is associated with lack 
of muscle strength and physical function and therefore forms the rationale for progressing the 
exercise therapy. 
- 
Circulatory exercises. The patients are instructed to do circulatory exercises to prevent 
edema and loss of muscle in the whole leg. The exercises are toe curls, flexion and extension 
for knee and hip. From week three Active range of motion (ROM) is allowed outside the 
walker boot, 3x10 rep 5 times per day. ROM for dorsiflexion is restricted beyond neutral 
position of the foot. Position: seated with bent or straight knee. It is important that the 
position is secure with no risk of sudden movement of the foot caused by externally forces 
(nearby persons, animals or other moving objects). 
 
Exercise descriptors 
Table of Toigo and Boutellier Exercise descriptors available in appendix A 
 
 
 
 
 

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Schedule of the exercise program: 
Exercises 
  
  
 
  
  
  
  
  
  
  
  
  
  
  
  
  
Elastic 2 
Elastic 2 
Elastic 2 
Elastic 1 
Heelrise 
Heelrise 
Heelrise 
Heelrise 
Heelrise  
Heelrise 
Heelrise 
Iso stand Iso stand 
Iso stand Iso stand 
Iso 
Iso 
Iso 
Elastic 1 
Elastic 1 
Elastic 1 
Elastic 1 
Iso 
ROM 
ROM 
ROM 
ROM 
ROM 
ROM 
ROM 
Weeks 
1 
2 
3 
4 
5 
6 
7 
8 
9 
Immobilizing Walker, 3 wedges 
Walker, 2 wedges 
Walker, 1 wedge 
Walker, no wedge 
Weight 
bearing 
Non WB 
  
P- WB, 2 crutches 
 
P-WB, 1-2 crutches 
 
Full WB, crutches for long walk 
 
Rationale 
 
 
 
A.  
Facilitation 
 
B.  
Initiation of load 
 
C. 
Progression to more load 
 
Total 
exercise 
dose (time 
under 
tension) 
 
 
Facilitation of 
muscle activity by 
isometric 
contraction without 
ROM 
Slow controlled movement to 
avoid peak forces on tendon 
while prioritizing long TUT to 
maintain/increase strength 
 
Improve strength (go to failure 
IF THEY ARE comfortable with it) 
 
 
 
Progression 
 
 
 
 
 
 
Progress from A to 
B: 
If patient feel 
comfortable doing 
facilitating exercises 
If clinical screening 
is OK at “2 week 
follow-up” (no 
tendon gap, equal 
ATRS, no pain 
during exercises). 
Progress from B to C: 
If patient feel comfortable doing 
“initiation of load” exercises. 
If exercises are managed well 
a. with regards to Toigo 
descriptors, 
b. without persistent pain or 
discomfort during and after 
exercises, c. no compensating 
movements while performing 
exercises. 
Progress from C to exercise and 
mobilize without walker: 
The decision to discontinue the 
walker is done at the Outpatient 
clinic. 
The exercises should provide the 
foundation for the patient to be 
confident in future decisions of 
choosing sufficient amount of 
load to improve the muscle 
performance while still avoiding 
too much strain on the healing 
tendon (i.e. avoid strenuous 
load, avoid stretching in 
dorsiflexion with load)  
 
Blue is usual treatment. Orange is the new additional treatment. Iso is isometric contractions. Elastic 1 is light 
load(yellow) and Elastic 2 is progression of load to stronger elastic band (red, blue, green). Heelrise is seated. ROM is 
unloaded range of movement. 
 
11b Criteria for discontinuing or modifying allocated interventions 
Each exercise session begins with assessing the progression of the tendon healing. In the first weeks 
with immobilisation, where physical examination is not possible, the patient is asked if there has 
been any constant or sudden pain or swelling and if there has been any excessive load to the tendon. 
In the following six weeks with the removable walker boot, there will also be a physical 
examination (as procedure in the outpatient clinic) of the tendon and muscle structure, and a 
measure of the Achilles Tendon Resting Angle (ATRA).32 

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In case of deviation from the protocol or adverse events, the primary investigator MC and the chief 
orthopaedic foot surgeon ILK will decide to either continue with modifications or to withdraw the 
patient from the study. (Further description in section 21a and appendix B) 
 
11c Strategies to improve adherence 
During the first visits the patients are informed about the importance of adherence to the exercise 
intervention. At the sessions the primary investigator will motivate the patients to perform the 
exercises. To ensure adherence to the home exercise program there will be a pamphlet with detailed 
description of the exercises. At each session the primary investigator will ask about the home 
exercises and the patients can ask questions. 
 
11d Relevant concomitant care and intervention that are permitted or prohibited during the 
trial 
During the first nine weeks of treatment the patients are advised to avoid activities with high load 
on the foot, concentrate on oedema prophylaxis and training for a better overall result. Most 
activities of daily living will be possible, but is advisable to take sick leave from work in the first 
two to nine weeks or longer depending on the workload. 
 
12. Outcomes 
For this feasibility study there are several outcome of interest, but no predefined single primary 
outcome. The main focus will be to test the feasibility of the exercise intervention by setting values 
for fulfilment of a range of outcomes and process variables deemed of importance to patients and 
safety. The outcomes will concern the patient’s acceptability of the intervention, adherence to the 
intervention and safety of the healing tendon.  
The exercise program is considered feasible if: 
1. The acceptability of the exercise program is 80%  
a. Defined as: ≥13/16 patients will rate the acceptability of the intervention as 
“acceptable” 
2. The adherence to the exercise program is 50% 
a. Defined as: ≥13/16 patients will perform ≥ 50% of the exercise sessions possible 
from start to end of week 9 
 
Outcomes:  
Patient acceptability: The patients will rate their acceptability (willingness) to perform the 
exercises on a 7-point Likert scale ranging from “very unacceptable” to “very acceptable”. This is 
not a measure of whether the patient’s symptoms have improved to normal physical function or any 
other satisfactory level at the specific time, but if it matches, their expectations of the content of an 

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exercise program in this early phase and how they tolerate performing the exercises. The 
intervention program is categorised as “Unacceptable” if rated as the three lower scores (“very 
unacceptable” to ”slightly unacceptable”) and  categorised as “Acceptable” if rated as the four 
higher scores (“neither acceptable or unacceptable” to “very acceptable”) 
- 
Clinical relevance: When developing a new exercise program it is essential to investigate if 
the patients are willing to perform the exercise program. If the intervention is unacceptable 
to the patient it is not feasible to embark on a large scale RCT. To categorise the 
intervention program as “Acceptable”, it is considered important that the patients does not 
rate it as “unacceptable”. 
Compliance with the intervention: The patients will register the number of training sessions and 
exercises they perform each day in a training journal. The compliance is measured as the mean 
number of exercise sessions they perform. The timeframe will be from the day they start the 
exercises to the end of week 9. 
- 
Clinical relevance: the exercise program is based on home exercises which should be easy to 
understand and perform without the need for supervising of a physiotherapist, as this will be 
both time consuming and with much higher costs. Total compliance to the exercise program 
is not expected, but even then reporting concerning exercise compliance are very poor with 
compliance as low as 45% or less for chronic diseases.33-35 The magnitude of this exercise 
program should leave room for patients with higher physical level or motivation, but the 
success rate should reflect the reality of compliance for most patients. 
 
Secondary outcomes 
The fear of re-rupture. When asked, the patients mention the fear of re-rupture and feeling the 
“pop” of the tendon as the worst thing that could happen again. This could influence the willingness 
to participate in the early exercises. The Tampa scale of Kinesiophobia (TSK) is used and validated 
for backpain, but has previously been used for Achilles tendon rupture evaluation36 as the questions 
about kinesiophobia could have associations to how patients with Achilles tendon rupture manage 
rehabilitation and return to sports. The questionnaire consists of 17 items concerning pain and 
kinesiophobia and has 4 answers from “Strongly disagree” to “Strongly agree”. During the exercise 
intervention period and at 3 months follow-up the patients will fill out the score and subsequently 
they are asked to rate the appropriateness of the score on a 7 point Likert scale ranging from 
“strongly disagree” to “strongly agree”. Measured at 2 weeks, 10 weeks and 3 months. 
The most frequently used patient reported outcome for Achilles tendon rupture is the Achilles 
Tendon total Rupture Score (ATRS).37 It contains 10 questions about physical performance in an 
11-point Likert scale from zero to ten with a total sum score of maximally 100. The scale only has 
labels for 0 and 10 (“major limitations/symptoms” and “no limitations/symptoms”). The 
questionnaire will be filled out by the patients at baseline for a pre-rupture level and at the 3 months 
follow-up. 
International Physical Activity Questionnaire (IPAQ) short form Danish version. It consists of 7 
items concerning physical activity as time spent performing vigorous and moderate activities, the 
time spent walking and sitting during the past week. The IPAQ gives an estimate of the total weekly 

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physical activity measured in MET-minutes per week and total minutes spent sitting.38 The 
questionnaire will be filled out by the patients at baseline for a pre-rupture level and at the 3 months 
follow-up.  
Achilles tendon resting angle (ATRA) is validated as an indirect measure of the Achilles tendon 
length.32,39,40 It is measured in degrees between the axis of the fibula (from malleol to proximal 
head) and the line from the tip of the fibula to the head of the Fifth metatarsal bone. The ATRA will 
be measured at 10 weeks and at 3 months followup. 
Achilles tendon properties - length measured by ultrasound using Barfods Ultrasound length 
measure for tendon length41 will be performed at 10 weeks and 3 months. 
Achilles tendon properties – cross-sectional area measured by ultrasound at the rupture site42 will 
be performed at 10 weeks and 3 months. 
Delay in start of exercises. At the two week visit to the outpatient clinic all patients will be clinical 
assessed when the immobilising orthosis is removed. The progression of the treatment is based on a 
combination of clinical assessments of the tendon structure, no palpable gap at the rupture and a 
foot position in equinus. Delay in starting the exercise program is measured in days from start to 
end of week 9. 
Safety and Adverse events. The number of serious and minor adverse events is registered in a pre-
defined list based on Common Terminology Criteria for Adverse Events43 and the patients will be 
asked open questions at each session. Serious Achilles tendon injury adverse events are re-rupture, 
non-union of the tendon or deep vein thrombosis (DVT). Muscle soreness or mild pain is 
considered inevitable and normal when initiating exercises after a period of immobilisation. 
Measured at 10 weeks and 3 months follow-up. 
Muscle endurance is measured in the seated position with the MuscleLab measurement system 
(Ergotest Technology, Oslo, Norway).44 External weight load on the knee is calculated to 50% of 
the bodyweight. A linear encoder is attached to the heel of the patient’s shoe. When heel-rise is 
performed, the string is pulled and the sensor measures the muscle endurance. Measured at 3 
months follow-up. 
 
13. Participant timeline 
Time schedule of enrolment  
FEASIBILITY STUDY 
STUDY PERIOD 
 
Enrolment 
Post-allocation 
Close-
out 
TIMEPOINT 
Day 1-7 
Week 2 
Week 3-
4 
Week 5-
6 
Week 7-
8 
2 
months 
3 
months 
ENROLMENT: 
 
 
 
 
 
 
 
Eligibility screen 
X  
 
 
 
 
 
 
Informed consent  
X 
 
 
 
 
 
 

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INTERVENTIONS: 
 
 
 
 
 
 
 
Facilitation of muscle 
 
 
 
 
 
 
 
Resistance exercise 
 
 
 
 
 
 
 
ASSESSMENTS: 
 
 
 
 
 
 
 
Prescore ATRS, IPAQ 
X 
 
 
 
 
 
 
Demographics 
X 
 
 
 
 
  
 
FEASIBILITY OUTCOMES: 
 
 
 
 
 
 
 
Patient acceptability 
 
X  
X  
X  
X  
X  
X  
Compliance with the intervention 
 
X  
X  
X  
X  
X  
X  
SECONDARY OUTCOMES: 
 
 
 
 
 
 
 
Adverse events 
 
X  
X  
X  
X  
X  
X  
PROM: ATRS, IPAQ 
 
 
 
  
 
 
X  
Tampa scale of Kinesiophobia TSK 
 
X  
 
  
 
X 
X  
Agreement of TSK 
 
X  
 
 
 
X  
X  
Physical measures (ATRA, UL of 
tendon length and cross-sectional 
area) 
 
 
 
 
 
X 
X 
Seated heel-rise endurance test 
 
 
 
 
 
 
X 
Delay in intervention start 
 
 
 
 
 
X  
 
 
14. Sample size considerations 
Since this is a feasibility study and we are primarily interested in estimates of feasibility and 
acceptability, no formal sample size calculation will be performed. Estimated number of 
participants is 16, which seems appropriate compared to the estimations for the following RCT. The 
overall incidence of Achilles tendon ruptures presenting at our hospital is approximately 80 per 
year. 
 
15. Recruitment Strategies for achieving adequate participant enrolment to reach target sample size
 
 
The participants are recruited in the Emergency department at Aalborg University Hospital or at the 
Orthopaedic Outpatient Clinic. All relevant subjects in this region will pass through these 
departments.  
All medical and administrative staff involved in treating the patients will be informed of the project 
and notified of the inclusion/exclusion criteria. There will be written information for staff and 
patients.  

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On a daily basis, the referral lists will be searched to retrieve all incoming journals for new acute 
Achilles tendon ruptures. Patients potentially eligible for the project will be contacted by the 
Primary Investigator to explain the study. If the patient is potential eligible, an early appointment in 
the outpatient clinic is arranged, where the patient receive the oral information about the project. 
Final inclusion will take place at this meeting if the eligibility is confirmed.  
Patients will be given the possibility of contacting the project manager by phone or Email, if they 
have questions. The intervention will take place at the hospital and be coordinated with the usual 
appointments in the outpatient clinic.  
 
Methods: Assignment of interventions (for controlled trials) 
16-17 
N/A 
 
Methods: Data collection, management, and analysis 
18. Data collection methods 
18a Plans for assessment and collection of outcome. 
Baseline data will be collected at the first appointment in the outpatient clinic. During the 
intervention the patients will be followed closely and monitored on compliance to the exercise 
program, progression of tendon healing and adverse events. At every session there will be an 
assessment of the clinical measures and the patient’s evaluation of the intervention. Assessment of 
outcome takes place after three months and will include patient reported questionnaires and 
physical measurements of leg strength and tendon length. 
 
18b Plans to promote participant retention and complete follow-up, including list of any 
outcome data to be collected for participants who discontinue or deviate from intervention 
protocols. 
Each appointment will be registered in the hospitals booking system and this features a possibility 
of having text messages prior to the appointments. If the patients fail to attend an appointment, the 
study manager will call the patient and offer another appointment. If the patient decides to leave the 
study, the reason for leaving will be registered. 
 
19 Data management 
Data will be entered in REDCap hosted at Aalborg University Hospital. It is a secure web 
application for building and managing online surveys and databases. Some baseline data will be 
imported from the Danish Achilles tendon Database DADB. Both databases has secure logged 
entry. Any paper forms will be kept in a locked cabinet in the Physiotherapy at the study site. All 

Protocol_Feasibility_ver 1.0 
Side 15 af 24 
 
data will be kept for 10 years after completion of the study in accordance with The European Code 
of Conduct for Research Integrity. 
 
20. Statistical methods 
20a 
STATA ver. 15 will be used for the statistical analysis. 
The following criteria will have to be completed to conclude feasibility of the intervention: 
1. ≥13/16 patients will rate the acceptability of the intervention as “acceptable” 
2. ≥13/16 patients will perform ≥ 50% of the exercise sessions possible from start to end of 
week 9 
 
Feasibility will be presented as: 
Patients acceptability as median and quartiles. Criteria fulfilment of 80% as number and percentage 
of patients scoring “acceptable”. Adherence to the intervention(compliance) as number of fulfilled 
sessions and percentage. Criteria fulfilment of 50% as number and percentage of patients 
performing  ≥50% of the exercises. The feasibility of the main outcomes will be measured at 10 
weeks and the secondary outcomes at 3 months follow-up. Descriptive information will be 
registered at baseline: Age, sex, height, weight, IPAQ, ATRS. Baseline and follow-up data will be 
presented as means with standard deviations. 
Reasons for exclusion and for withdrawal will be summarised. Safety will be presented as number 
and percentage of patients reporting adverse events divided in major and minor events. Time from 
treatment start to beginning exercises as mean days and range.  
 
20b Methods for any additional analyses (eg, subgroup and adjusted analyses) 
N/A 
 
20c Definition of analysis population relating to protocol non-adherence (eg, as randomised 
analysis), and any statistical methods to handle missing data (eg, multiple imputation) 
The intention-to-treat principle is used for analyses and all participants are included in the analyses 
regardless of the acceptability or compliance to the intervention. 
 
Methods: Monitoring 
21. Data monitoring.  
21a Composition of data monitoring committee (DMC); 

Protocol_Feasibility_ver 1.0 
Side 16 af 24 
 
Safety of the tendon healing has great importance in this feasibility study. There will be a data 
monitoring committee(DMC) with the principal purpose of monitoring adverse events. The study 
setup will aim at preventing adverse events by monitoring the tendon healing and setting threshold 
values for initiation and progressing the exercises in the intervention. The DMC will be composed 
of the principal investigator (MC), the chief orthopaedic foot surgeon (ILK) and an orthopaedic 
surgeon not otherwise involved in the study. All symptoms and adverse events will be registered by 
the principal investigator (Appendix B). The DMC will assess and grade  symptoms that are not 
within normal trauma reactions or normal exercise reactions and especially events considered a 
serious or possible serious adverse event. DMC will decide, whether to delay the proceeding of the 
intervention or the patient should be withdrawn from the study due to the adverse event (See section 
11b). The adverse events will be graded 1 to 5 according to the Common Terminology Criteria for 
Adverse Events v4.03.43  
 
21b  
If the rate of re-rupture or other serious adverse events is noted to be exceptionally high or increases 
rapidly after the intervention has been implemented, the data monitoring committee can recommend 
and decide to terminate the trial. No formal stopping rules has been set, as this is a feasibility study. 
 
22. Harms. Plans for collecting, assessing, reporting, and managing solicited and 
spontaneously reported adverse events and other unintended effects of trial interventions or 
trial conduct 
All patients receive information about possible adverse events relative to the Achilles tendon 
rupture in general and to the specific intervention. In case of serious adverse events they are 
encouraged to seek immediate medical attention and for minor adverse events to contact the 
principal investigator by phone. At each session the patients will answer questions of possible 
adverse events during and between the sessions. The primary investigator will be monitoring a 
predetermined set of key points at each session.  
 
23. Auditing 
N/A 
 
Ethics and dissemination 
24. Research ethics approval 
Before initiation of the project the study protocol, informed consent and patient information will be 
approved by: 
 The Physiotherapy and Occupational therapy department and the Orthopaedic Surgery at 
Aalborg University Hospital 

Protocol_Feasibility_ver 1.0 
Side 17 af 24 
 
 The Ethics committee of North Denmark Region 
 
25. Protocol amendments 
 
26.ab Consent or assent 
The primary investigator will obtain informed consent by the participants. 
 
27. Confidentiality 
All personal data collected on potential and enrolled participants is collected by telephone screening 
or at the baseline appointment. Data will be kept secure and for 10 years. 
The GDPR – General Data Protection Regulation is followed. The study is registered at The Danish 
Data Protection Agency at Aalborg University Hospital. 
 
28. Declaration of interests 
All authors have no competing interests. 
 
29. Access to data 
All authors will have access to the full dataset before publication. The dataset will be stored at the 
sponsor site, Aalborg University hospital. 
 
30. Ancillary and post-trial care 
During and after completion of the study the included patients will be followed in the outpatient 
clinic and in The Danish Achilles tendon Database (DADB). Any serious adverse event occurrence 
will be reported and consulted with the Chief foot surgeon (ILK) the same day for re-ruptures or 
DVT and within 3 days for minor adverse events. 
 
31. Dissemination policy 
31a Plan for publication 
The results of the study will be published in an international peer-reviewed journal for example the 
Journal of Pilot and Feasibility Studies or the Journal of Orthopaedic & Sports Physical Therapy 
(JOSPT). The preliminary title is: Development and feasibility of an early progressive strength 
exercise programme for acute Achilles tendon rupture. 

Protocol_Feasibility_ver 1.0 
Side 18 af 24 
 
The results will also be presented at relevant physiotherapy and orthopaedic conferences. 
Guidelines and the exercise protocol will be made available for online download, to ensure 
translation of the research results into useful information for clinical practice.  
 
31b Authorship eligibility guidelines and any intended use of professional writers 
All co-authors are expected to make substantial scientific contributions that will qualify them as co-
authors according to the International Committee of Medical Journal Editors (ICMJE) 
recommendations for authorship45: 
 
Substantial contributions to the conception or design of the work; or the acquisition, analysis, or 
interpretation of data for the work; AND 
 
Drafting the work or revising it critically for important intellectual content; AND 
 
Final approval of the version to be published; AND 
 
Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy 
or integrity of any part of the work are appropriately investigated and resolved. 
 
MC will draft the manuscript with input from all the authors. MSR, ILK, JAZ and KGS will all 
participate with valuable scientific contributions to the manuscript. 
Expected author list: Christensen M, Silbernagel KG, Zellers JA, Rathleff MS, Kjær IL 
 
31c Plans for granting public access 
Data will be available upon reasonable request. 
 
Appendices 
32. Informed consent materials: 
 
33. Biological specimens: 
None 
 
 
 
 

Protocol_Feasibility_ver 1.0 
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December 2017. 
  
 

Exercise descriptors table_ver 1.0 
Appendix A. Table of the three exercises in the Feasibility study. 
Toigo & 
Boutellier 
exercise 
descriptors 
Isometric contraction
Seated heel-rise
Elastic band
X1 Load
magnitude 
15-20 RM
 
15-20 RM
Progress to 15RM week 6/7 
First step is to  increase 
repetitions and second step is 
to add more load 
 
15-20 RM
Progress to 15RM week 
6/7 
First step is to increase 
repetitions and second 
step is to add more load 
 
X2 number of 
repetitions 
5
10-15
10-15
X3 number of sets
5
3
3
X4 rest btw sets
5 sec
10 sec
10 sec
X5 number of 
exercise 
interventions 
Every hour (approx 15
hours per day) for 
week 2-3,  
then change to 5 times 
per day in week 4-9 as 
warm-up exercise.  
 
5 per day
5 per day
X6 duration of 
the experimental 
period 
Week 2 to 9
Week 3 to 9
From week 5 to 9
 
X7 Fractional and 
temporal 
distribution of the 
contraction 
modes per 
repetition and 
duration (s) of 
one repetition 
5 sec
3s shortening
2s isometric 
3s lengthening 
3s-2s-3s
(Focus is on the 
concentric phase. 
Important not to push 
beyond the neutral 
position in the eccentric 
phase) 
X8 Rest in-
between 
repetitions 
2
2
2
X9 Time under 
tension  
125 s per session
1875 s per day (hourly) 
 
625 s per day (5 times) 
 
240s per session
1200s per day 
240s per session
1200 s per day 
X10 Volitional 
muscular failure 
No
No
No
X11 Range of 
motion 
No range of motion. 
The foot is immobilized 
in equinus according to 
the number of wedges. 
From plantarflexed foot 
position on the wedges to 
more plantarflexed, when 
performing the heel-rise 
Dorsiflexion above 
neutral is not allowed. 
Full plantarflexion 
allowed. 
 
X12 Recovery 
time in-between 
exercise sessions 
1 hour
3 hours
3

Exercise descriptors table_ver 1.0 
X13 Anatomical 
definition of the 
exercise (exercise 
form) 
Isometric contraction 
is performed inside the 
walkerboot with the 
foot in equinus 
according to the 
weekplan.  
 
Push the forefoot 
against the bottom of 
the walker and feel the 
contraction of the leg 
muscles as if you are 
going to make a heel-
rise, but the walker 
boot restricts your 
motions. Extend the 
big toe to minimize the 
activity of the muscles 
for the big toe and 
increase activity of the 
leg muscles. 
 
Seated heel-rise with leg in 
walker with “the wedges of 
the week”. Open straps and 
liner of walker. Knee in 90 
degrees position. Hold one 
hand at the back of the walker 
to stabilize.  
 
Extend the big toe. Lift the 
heel up from the 
walker/wedges. Make sure 
that you are using the leg 
muscles and not pulling up 
the leg with your thigh 
muscles. Rest the foot on the 
forefoot pad rather than on 
the toes alone. 
Progression: add weight on 
knee (either sandbag/rice, 
water bottle, upper body. 
Performed seated with 
straight knee. Wrap the 
elastic band around the 
forefoot and hold both 
ends in the hand. Tighten 
the band, but make sure 
that the foot is not pulled 
beyond 90 degrees. 
 
Extend the big toe. Press 
the foot down against the 
tightened elastic band as 
far as you can move the 
foot. Hold the position 
and then slowly pull up 
the foot again, but still 
with a tightened band. 
Progression: Change 
elastic band to other 
color (more strength) 
 
Borgs scale – Perceived exertion during exercise (/10) is used to guide the patients to progress or regress 
the load in each exercise. The recommended level being “easy” to “hard” (2-5/10). It  is emphasized that 
the exercises must not cause sudden or severe pain in the tendon, but muscle soreness is to be expected. 
 
Progression: 
Progression of the exercises will be a continuous process. There are three main phases: facilitating, 
initiation of load, progression to more load. When progressing to the next phase or new type of exercise 
the following criteria has to be observed: 
The load magnitude of the present exercise should be accomplished with the patient feeling comfortable 
doing the exercises and without persistent pain or discomfort during and after exercises. 
 
 

Adverse events protocol ver 1.0 
1 
 
Appendix B. Adverse events / safety protocol 
Feasibility of an early progressive strength exercise program for acute Achilles tendon 
rupture.  
 
Collecting information about safety and adverse events.  
Questions of adverse events will be asked at each exercise session, before the intervention starts. 
 
Part 1.  
Open questions to the patient:  
Have you experienced any symptoms since the last time you were here?  
- 
Symptoms from your Achilles tendon, lower leg or foot? 
- 
Symptoms from other parts of the body? 
Have you experienced any new trauma or large load since last time you were here?  
- 
On your Achilles tendon? 
- 
To other parts of the body? 
The response is registered as formulated by the patient. 
 
Part 2.  
Specific questions. Have you experienced any of the listed symptoms?  
 
Symptoms
Yes /No
Comments.
Description, location, cause, time, 
other scores (eg VAS) 
Grade assessment. The
specific symptoms are rated 
on C1-C7 or other relevant – if 
not possible then on the 
general scale (“C general”) 
(C=CTCAE) 
Pain
 
Describe 
C1
- 
Pain on VAS 
scale 
If you have (or had) pain then place 
the marker at the scale 
corresponding to your pain. 
(Use A4 paper with precise 
measures or numeric scale in 
Redcap)  
Cramps 
 
Describe
C7 Myalgia 
Swelling/edema
 
Describe
C3 Localysed edema or
C4 Edema limbs 

Adverse events protocol ver 1.0 
2 
 
Discomfort, unease, 
itch, sleeping 
sensation 
 
Describe
C general
Breathing difficulties 
Describe
C5 Thromboembolic event
Exercise induced 
pain in leg muscles 
during or after the 
exercises. 
Describe
C7 Myalgia 
Other?
Describe nature of 
symptoms. 
Describe
C general is used if no specific
topic is applicable 
 
Part 3:  
Objective assessment by principal investigator. 
Symptoms
Yes /No
Comments.
Description, location, cause, time, 
other scores (eg VAS) 
Grade assessment. The
specific symptoms are rated 
on C1-C7 or other relevant – 
if not possible then on the 
general scale (“C general”) 
(C=CTCAE) 
Achilles tendon 
palpation – is there a 
gap? 
 
C2 Muskuloskeletal 
deformity 
Achilles tendon pain 
at palpation 
 
C1 Pain
Achilles tendon 
length v ATRA 
 
C2 Muskuloskeletal 
deformity 
Muscle pain
 
C7 Myalgia
 
Local edema at 
Achilles tendon  
 
C3 Localised edema
Edema in foot-ankle 
or lower leg 
 
C4 Edema limbs
Redness or pressure 
marks  
 
C8 Skin Ulcerations
 
Signs of DVT – pain, 
edema, tension in 
musculature 
 
C5 Thromboembolic event
Other
Specify  
 
Cgeneral is used if no 
specific topic is applicable 
 
 
How to grade the severity of adverse events 
Grades (CTCAE) of the typical events. Consult CTCAE document if others are needed. 
 
 

Adverse events protocol ver 1.0 
3 
 
Cgenerel 
Grade refers to the severity of the AE. The CTCAE displays Grades 1 through 5 with unique clinical 
descriptions of severity for each AE based on this general guideline: 
Grade 1  
Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention 
not indicated. 
Grade 2  
Moderate; minimal, local or noninvasive intervention indicated; limiting age-appropriate 
instrumental ADL*. 
Grade 3  
Severe or medically significant but not immediately life-threatening; hospitalization or 
prolongation of hospitalization indicated; disabling; limiting self care ADL**. 
Grade 4  
Life-threatening consequences; urgent intervention indicated. 
Grade 5  
Death related to AE. 
 
C1: Pain (page 59) 
Definition: A disorder characterized by the sensation of marked discomfort, distress or agony. 
Grade 1 
Mild pain  
Grade 2 
Moderate pain; limiting instrumental ADL 
Grade 3 
Severe pain; limiting self care ADL 
Grade 4+5 
- - 
 
C2: Musculoskeletal deformity (Herunder re-ruptur og manglende heling) (page 124) 
Definition: A disorder characterized by of a malformation of the musculoskeletal system. 
Grade 1 
Cosmetically and functionally insignificant hypoplasia 
Grade 2 
Deformity, hypoplasia, or asymmetry able to be remediated by prosthesis e.g., shoe insert) 
or covered by clothing 
Grade 3 
Significant deformity, hypoplasia, or asymmetry, unable to be remediated by prosthesis or 
covered by clothing; disabling 
Grade 4+5 
- - 
 
C3:Localized edema (page 58)  
Definition: A disorder characterized by swelling due to excessive fluid accumulation at a specific anatomic 
site 
Grade 1 
Localized to dependent areas, no disability or functional impairment 
Grade 2 
Moderate localized edema and intervention indicated; limiting instrumental ADL 
Grade 3 
Severe localized edema and intervention indicated; limiting self care ADL 
Grade 4+5 
- - 
 
C4: Edema limbs (page 55) 
Definition: A disorder characterized by swelling due to excessive fluid accumulation in the upper or lower 
extremities. 
Grade 1 
5 - 10% inter-limb discrepancy in volume or circumference at point of greatest visible 
difference; swelling or obscuration of anatomic architecture on close inspection 
Grade 2 
>10 - 30% inter-limb discrepancy in volume or circumference at point of greatest visible 
difference; readily apparent obscuration of anatomic architecture; obliteration of skin folds; 
readily apparent deviation from normal anatomic contour; limiting instrumental ADL 
Grade 3 
>30% inter-limb discrepancy in volume; gross deviation from normal anatomic contour; 
limiting self care ADL 
Grade 4+5 
- - 

Adverse events protocol ver 1.0 
4 
 
 
C5: Thromboembolic event (page 193) 
Definition: A disorder characterized by occlusion of a vessel by a thrombus that has migrated from a distal 
site via the blood stream. 
Grade 1 
Venous thrombosis (e.g., superficial thrombosis) 
Grade 2 
Venous thrombosis (e.g., uncomplicated deep vein thrombosis), medical intervention 
indicated 
Grade 3 
Thrombosis (e.g., uncomplicated pulmonary embolism [venous], nonembolic cardiac mural 
[arterial] thrombus), medical intervention indicated 
Grade 4 
Life-threatening (e.g., pulmonary embolism, cerebrovascular event, arterial insufficiency); 
hemodynamic or neurologic instability; urgent intervention indicated 
Grade 5 
Death 
 
C6: Gait disturbance (page 57) 
Definition: A disorder characterized by walking difficulties. 
Grade 1 
Mild change in gait (e.g., wide-based, limping or hobbling)  
Grade 2 
Moderate change in gait (e.g., wide-based, limping or hobbling); assistive device indicated; 
limiting instrumental ADL 
Grade 3 
Disabling; limiting self care ADL 
Grade 4+5 
- - 
 
C7: Myalgia (page 124) 
Definition: A disorder characterized by marked discomfort sensation originating from a muscle or group of 
muscles. 
Grade 1 
Mild pain  
Grade 2 
Moderate pain; limiting instrumental ADL 
Grade 3 
Severe pain; limiting self care ADL 
Grade 4+5 
- - 
 
C8: Skin Ulcerations (page 186) 
Definition: A disorder characterized by circumscribed, inflammatory and necrotic erosive lesion on the skin. 
Grade 1 
Combined area of ulcers <1 cm; nonblanchable erythema of intact skin with associated 
warmth or edema 
Grade 2 
Combined area of ulcers 1 – 2 cm; partial thickness skin loss involving skin or subcutaneous 
fat 
Grade 3 
Combined area of ulcers >2 cm; full-thickness skin loss involving damage to or necrosis of 
subcutaneous tissue that may extend down to fascia 
Grade 4 
Any size ulcer with extensive destruction, tissue necrosis, or damage to muscle, bone, or 
supporting structures with or without full thickness skin loss 
Grade 5 
Death 
 
 
Other: 
Bruising: (page 88) 
Fall (page 89) 
Generalized muscle weakness (page 121)