The main purpose of the study is to compare the patient-reported outcomes and adverse events of two different rehabilitation regimes for patients undergoing non-surgical treatment of Achilles Tendon Rupture. Thus, using a pre-post study design we will compare whether patients participating in an 8-week liberal rehabilitation regime will achieve the same, or better, self- reported functional ability, without increased risk of adverse events, in the first two years following injury, compared to an 11 weeks more restrictive rehabilitation regime..

Background:

The Achilles tendon is the most commonly injured tendon in the lower extremity, and can be treated either surgical or non-surgical. Previous studies have investigated early controlled motion and weight-bearing for non-surgically treated Achilles Tendon Rupture (ATR). Early motion may cause tendon elongation, which leads to decrease in push off strength, and thus potentially a poorer functional outcome. Conversely, delayed initiation of mobilisation and weight-bearing may similarly hinder or delay optimal recovery of function and return to work and sports. The correct treatment and rehabilitation, including the timing of rehabilitation initiation, may therefore be crucial to ensure the patients functional ability.

Most hospitals in Denmark treating patients with ATR, provide a regime of 8-9 weeks of treatment for non-surgically treated patients. At Aarhus University Hospital (AUH), however, a more restrictive regime has been provided for these patients in the past 7 years, with a treatment period of 11 weeks after injury, and with no or limited weight-bearing or exercises.

A previous retrospective study at AUH including 100 patients undergoing non-surgical treatment and the restrictive 11 week rehabilitation regime was conducted in 2023. The results documented a re-rupture rate of 4 %, comparable to the rate reported at the Danish ATR Database, and similarly comparable results on patient-reported disability measured with the Achilles tendon Total Rupture Score (ATRS). The Danish ATR Database includes data from 11 different hospitals in Denmark, where the majority have implemented a more liberal rehabilitation regime of 8-9 weeks of treatment with early weight-bearing and exercises. As a result of this retrospective study, we are changing the rehabilitation protocol of ATR at AUH, from 11 weeks restrictive regime, to an 8 weeks liberal regime.

Purpose:

With this quality assurance study we aim to compare patient-reported outcomes and adverse events in patients participating in an 8-week liberal regime compared to an 11-week restrictive regime following non-surgically treated ATR

Study design and setting:

This is an observational cohort study with prospectively collected patient-reported outcomes, conducted at AUH. First, 110 consecutive patients will be included while the existing 11-week restrictive regime is standard care, then the 8-week liberal regime will be implemented, and subsequently another 110 patients will be consecutively included.

Data collection procedures and outcomes:

Patients will receive a digital letter with a link to an online questionnaire to be completed at 6 months, 12 months and 24 months from the date of the treatment start.

Patients are asked to fill out the ATRS on functional ability, as well as additional questions regarding job status, return to sport, incidence of deep venous thrombosis, whether they have sustained a re-rupture, and their satisfaction with treatment they received at the hospital.

The ATRS is a 10-item questionnaire, with a score of 0 to 10 (worst-best), which has been found valid, reliable and responsive in this population.

Statistical analysis:

The primary outcome is the difference in the self-reported ATRS score at 12 months in patients participating in the 8-weeks regime compared to the 11-week regime.

The sample size needed to detect a minimal clinical important difference of 10 points (SD 18) between the two groups is 102, with a significance level of 5% and a power of 80%. To allow for subgroup analysis and with an estimated rate of drop-out of 20%, a minimum of 200 patients will be included.

Inclusion criteria:

• Patients with an acute achilles tendon rupture treated non-surgically at AUH
• Treatment start maximum 14 days after time of rupture
• ≥18 years
• Understand and read Danish

Exclusion criteria:

• Patients who have not followed the regime at AUH (e.g. terminated use of the ROM- walker prematurely or similar)
• Bilateral ATR or rupture of the opposite in the treatmentperiod

The study population consists of approx. 220 consecutive acute achilles tendon rupture patients, treated non-surgically at Aarhus University Hospital from 2022 to approximately 2028.