Blood Flow Restriction Exercise in Patients With an Achilles Tendon Rupture

The Effectiveness of Low-load Blood Flow Restriction Exercise in Patients With an Acute Achilles Tendon Rupture Treated Non-surgically

The goal of this clinical trial is to gain insights into the effects of Blood Flow Restriction Exercise (BFRE) in patients with an acute Achilles tendon Rupture. The main questions it aims to answer are:

Is BFRE an effective adjunct to usual care when compared with only usual care? When is the optimal timing for initiating BFRE: In the early treatment stage or at the later stage after hospital treatment? Participants will receive an intervention comprising 12 weeks of BFRE as an adjunct to usual care.

• Either in the initial 1-12 weeks after Achilles tendon rupture, or
• In the following 13-24 weeks after Achilles tendon rupture

Researchers will compare the two groups at 13 weeks (3 months) to compare BFRE to usual care, and at 25 weeks (6 months) to compare the two time points for initiating BFRE (early vs. late).

This is an assessor-blinded, randomized, controlled multicenter trial with patients allocated 1:1 to one of two parallel groups, with follow-up times at weeks 13 and 25 after allocation.

Patients with an acute Achilles tendon rupture treated non-surgically are eligible for inclusion. All patients will receive a 12-week BFRE program, either in weeks 1-12 or 13-24 post allocation, as an add-on to usual care.

The BFRE program is performed three times weekly on the injured leg at 80% of the limb occlusion pressure required to restrict the arterial blood flow fully.

Outcome measures are assessed at baseline, week 13, and week 25 after allocation. The primary outcome at the week 13 follow-up is the Single-Leg Heel-Raise test which assesses the patient's ability to raise the heel of the injured leg a minimum of 2 cm. The primary outcome at the week 25 follow-up is the Achilles Total Tendon Rupture Score which assesses the patient's self-reported symptoms and physical activity.

During most of the initial trial phase (weeks 1-12), patients are treated at local hospitals, where recruitment, assessment, and randomization occur. Usual care at the hospitals consists of ankle immobilization with a gradual return to weight-bearing in the following weeks. In the latter half of the trial phase (weeks 13-24), patients have transitioned to municipal care, where usual care includes diverse exercises performed at home or training facilities.

Inclusion Criteria:

• aged 18 years or older
• have started initial treatment within 72 hours of Achilles tendon rupture
• understand written and spoken Danish

Exclusion Criteria:

• bilateral Achilles tendon rupture
• previous Achilles tendon rupture in either leg
• decreased lower extremity function, caused by conditions other than Achilles tendon rupture
• treated with fluoroquinolones within the last six months
• treated with corticosteroid injection(s) in the area near the Achilles tendon within the last six months.
• diabetes
• previous diagnosed thrombosis
• Known atherosclerosis in the peripheral arteries of the lower limb
• other reasons for exclusion (cognitive deficits, inability to provide informed consent, requiring cast-treatment due to low compliance regarding gradual wedge removal, etc.)