Effects of Direct Functional Mobilization After Achilles Tendon Rupture on Healing and Outcome
Phase: NA
Conditions: Achilles Tendon Rupture, Deep Venous Thrombosis
Sponsor: Karolinska University Hospital

Study protocol – Functional Mobilization and DVT – Final version  
 
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Early Functional Mobilization Prevents Immobilization-Induced Deep 
Venous Thrombosis  
 
Introduction 
Modern orthopedic surgery care aims at restoring musculoskeletal function of the patient as 
soon as possible without inflicting complications related to operation or to post-operative 
immobilization. Immobilization causes venous thromboembolism (VTE) resulting in deep 
venous thrombosis (DVT) and pulmonary embolism. 1 2  
 
Complications related to musculoskeletal trauma, operations and lower limb immobilization 
such as VTE and delayed healing represent increasing problems. The NHS, UK, has identified 
prevention of VTE as the number one prioritized intervention. 3 4 Each year 25,000 people in 
the UK die from VTE. This is a larger number than deaths attributable to breast cancer, AIDS 
and road traffic accidents combined. 3 4  
 
In some patient-groups with acute trauma, pharmacological prophylaxis of VTE (LMWH) is 
contraindicated, due to eg. high bleeding risk. Moreover, LMWH has been shown to have 
adverse effects on the healing process 5 and even delays fracture repair in animals. 6 Thus, 
there is a need of developing alternative treatment methods. Moreover, in patients with lower-
leg immobilization after injuries LMWH has shown low- or non-effectiveness. 7 8  
 
Current trends in orthopedic surgery must take account of well-informed patients with high 
demands on the orthopedic care including minimal risks associated with the surgical 
procedures, and short rehabilitation times. Early mobilization post-operatively has been a 
milestone in reducing the risk for DVT as well as to enhance healing. 9 However, some 
operative procedures still demand stabilization, i.e. plaster immobilization, to protect the 
healing tissue. Recently the detrimental effects of immobilization on tissue repair as well as the 
increased risk of DVT have been reported. 9-12 
 
So how do we counteract the effects of immobilisation in order to minimize post-operative 
complications and to expedite recovery? We hypothesize that one crucial principle is early 
mobilization with loading and activation of the calf muscles. Early mobilization with muscle 
activation can be achieved by dynamic orthosis treatment, which can gradually increase the 
range of motion.  
 
Patients immobilized in plaster cast after Achilles tendon rupture (ATR) are at especially high 
risk; the VTE incidence being 36-50%, irrespective of operation or conservative treatment. 7 13 
14 Hence, DVT preventive interventions during lower limb immobilization are often 
recommended. 2 Pharmacological prophylaxis has after ATR, however, shown not to effective 
in reducing the risk of DVT. 7 Whether early mobilization with dynamization could reduce the 
risk of DVT after ATR as compared to treatment-as-usual with plaster cast is yet unknown.    
 
Hypotheses 
 
1. Early functional mobilization after ATR compared to treatment-as-usual with plaster 
cast followed by orthosis treatment results in decreased incidence of DVT. 
2. The amount of weightbearing and the number of daily steps will influence the risk of 
DVT.  
 
Aims 

Study protocol – Functional Mobilization and DVT – Final version  
 
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In a prospective multicenter randomized double blind controlled study we will determine the 
effect of early mobilization with dynamization compared to plaster cast treatment and 
subsequent orthosis treatment during six post-operative weeks after Achilles tendon surgery 
with regards to: 
1. Incidence of DVT. 
2. Risk factors including the amount of weightbearing and number of daily steps on the 
risk of sustaining a DVT 
 
 
 
Primary Inclusion Criteria 
 
1. Acute Achilles tendon rupture accepted for surgery within 7 days. 
2. Age 18-75 years. 
 
Exclusion Criteria 
 
1. Inability or refusal to give informed consent for participation in the study 
2. Ongoing treatment with anticoagulant therapy 
3. Inability to comply with the study instructions 
4. Known kidney disorder 
5. Heart failure with pitting oedema 
6. Thrombophlebitis 
7. Recent thromboembolic event (during the preceding 3 months) 
8. Recent surgery (during the preceding month) 
9. Presence of known malignancy 
10. Current bleeding disorder 
11. Pregnancy 
12. Wound in the area of operation 
 
 
Study Design 
 
A prospective randomized multi-center study at the Karolinska University Hospital, Solna 
Huddinge, Södersjukhuset and Danderyds Hospital. We plan to include 150 patients between 
2013 and 2016. Consecutive patients will be randomized after acute Achilles tendon rupture 
surgery to treatment with either early mobilization with dynamization or standard plaster cast 
treatment for the first two weeks. From the second until the sixth postoperative week the early 
mobilization group will be treated with increased dynamization while the plaster cast group will 
be treated with a stable orthosis. The randomization will take place at the time of completion 
of surgery.  
 
The surgery will be carried out under local, spinal or general anesthesia without a use of 
tourniquet. The repair will consist of an end-to-end suture with modified Kessler technique. 
After surgery the control group patients will be immobilized in a standard below-knee plaster 
cast with the ankle in 30 degrees of equinus position. At the 2 weeks visit the control group will 
be immobilized in an orthosis until week 6 postoperatively.  
 
The patients in the early mobilization group will be immobilized in an orthosis (VACOped) 
which will allow mobility from 15 to 30 degrees of plantar flexion up to 2 weeks post-

Study protocol – Functional Mobilization and DVT – Final version  
 
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operatively. Week 2-6 postoperatively the orthosis will be dynamized to allow 25 degrees of 
mobility from 5 to 30 degrees of plantar flexion.  
 
 
Week 
Degrees° (ROM) 
Weight bearing 
 
Crutches 
0-2 
15°– 30 ° plantar flexion 
as tolerated within pain limit                Recommended 
2-6 
 5°– 30 ° plantar flexion 
full 
 
                Only if in pain  
 
 
Patients will be instructed to unload without the orthosis for one hour each day to let the ankle 
breathe. The mobilization of the patients will be recorded with a pedometer and with self rating 
scales. 
 
The study will be double blinded for the surgeon and for the assessor of DVT. 
 
End-points 
 
Incidence of VTE 
Assessment of DVT: At 2 and 6 weeks post-operatively, all patients will be screened for DVT 
in the operated leg by unilateral compression duplex ultrasound (CDU). Two experienced 
ultrasonographists, blinded to the treatment regimens, will perform all the CDU using a 
Philips CX 50 ultrasound machine (Philips Medical Systems, Andover, MA, USA). The 
standard procedure includes evaluation of all deep proximal and distal veins, including muscle 
veins, as well as vena saphena magna. The criteria for DVT diagnosis and the diagnostic 
procedure have been described earlier. 7 13 14 Proximal DVT will be defined as a thrombosis 
that involved the popliteal vein or any more proximal veins, with or without involvement of 
the calf veins. Briefly, the DVT diagnosis will be based on a transversal ultrasound 
compression test of the blood vessel, and assessment of blood flow in the veins by color 
Doppler flow.  
The compression duplex ultrasound scans that will be performed at two or six weeks will be 
re-evaluated after completion of the study, by analyzing the CDU film sequences. The second 
assessment will be performed by another ultrasonographist blinded to the treatment allocation. 
This post hoc examination will verify the first diagnosis and validate the methodology.  
Assessment of pulmonary embolism: Computer tomography will be used for diagnosis in 
patients with symptoms of pulmonary embolism. Assessors will be masked to the treatment 
allocation. 
 
Statistical Methods 
Sample size calculation is based on recent studies showing a 50% rate of CDU-verified DVT 
at 2 and 6 weeks after ATR. 13 15 Based on earlier studies and our own pilot study, we 
estimated early mobilization and IPC to confer a 50% risk reduction. 15 16 In each group, 63 
patients will be required to detect a difference of 25% in the incidence of DVT (two-sided 
type-I error rate = 5%; power = 80%). A 10% drop-out is accounted for, but our experience is 
less than that. On recommendations from the ethical committee, a ratio of 2:1 was chosen, 
since our hypothesis was that the early functional mobilization group would perform better. 
 
 
Separate protocols 
This is the protocol for assessment of the primary outcome of this study, i.e. DVT. Separate 
protocols are available for other outcome measures. 

Study protocol – Functional Mobilization and DVT – Final version  
 
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References 
 
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