Achilles tendon rupture is a common injury that can significantly impact strength, function, and quality of life. While non-surgical management using structured rehabilitation protocols such as the Swansea Morriston Achilles Rupture Treatment (SMART) protocol is increasingly adopted, there is limited evidence on long-term recovery outcomes, particularly beyond six months.

This study aims to evaluate recovery at 12-15 months following non-surgical management of Achilles tendon rupture in an NHS population. Participants will attend a single study visit during which plantarflexor muscle strength will be assessed using isokinetic dynamometry, and patient-reported outcomes will be collected using the Achilles Tendon Total Rupture Score (ATRS) and EQ-5D-5L questionnaire. Achilles Tendon Resting Angle (ATRA) will also be measured to provide an estimate of tendon elongation.

The primary objectives are to quantify plantarflexor strength recovery and self-reported functional outcomes. Secondary analyses will explore associations between strength, tendon elongation, quality of life, return to sport, and pre-injury symptoms.

This cross-sectional observational study will recruit adult patients managed non-surgically with the SMART protocol from Liverpool University Hospitals NHS Foundation Trust. Findings will provide clinically relevant data on long-term recovery following conservative treatment and may inform rehabilitation strategies and return-to-activity decision-making.

This study is a cross-sectional observational investigation designed to evaluate objective and patient-reported recovery outcomes following non-surgical management of Achilles tendon rupture using the Swansea Morriston Achilles Rupture Treatment (SMART) rehabilitation protocol. The study is conducted within a National Health Service (NHS) setting at Liverpool University Hospitals NHS Foundation Trust.

Participants will be identified from an established clinical database of patients who have sustained an Achilles tendon rupture and completed non-operative rehabilitation. Eligible individuals will be invited to attend a single assessment session at 12-15 months post-injury. This time point has been selected to reflect longer-term recovery, as previous literature has predominantly focused on early and mid-term outcomes.

Study Procedures and Data Collection During the study visit, participants will undergo a comprehensive assessment including objective, clinical, and patient-reported measures. Isokinetic dynamometry will be used to quantify plantarflexor muscle performance under controlled conditions. Testing will be standardised, including participant positioning, joint alignment, range of motion, and angular velocities. Outcome variables will include peak torque and torque relative to body mass, allowing both within-participant and between-participant comparisons.

Achilles tendon structural characteristics will be assessed indirectly using the Achilles Tendon Resting Angle (ATRA), a clinically applicable proxy for tendon elongation. Measurements will be taken bilaterally using a standardised protocol with repeated trials to improve reliability, and side-to-side differences will be calculated.

Participants will also complete validated patient-reported outcome measures to capture functional status and general health. Additional contextual variables, including return-to-sport status and pre-injury Achilles symptoms, will be recorded to enable exploratory subgroup analyses.

Data Management and Quality Assurance All study data will be recorded using a structured case report form and stored within a secure, NHS-hosted electronic data capture system (REDCap). Data will be pseudonymised at the point of entry, with each participant assigned a unique study identifier. Identifiable information will be stored separately from research data and accessible only to authorised study personnel.

Data quality will be maintained through predefined validation rules within the data capture system, including range checks and logical consistency checks across related variables. Regular data monitoring will be conducted by the research team to ensure completeness and accuracy. Source data verification may be undertaken by comparing selected data fields against original clinical records where necessary.

A data dictionary will be maintained to define all study variables, including measurement units, coding structures, and allowable ranges. Standard Operating Procedures (SOPs) will guide all aspects of study conduct, including participant identification, data collection, data entry, and data storage, ensuring consistency across sites.

Sample Size Justification The sample size has been determined based on statistical considerations for detecting meaningful differences in strength between limbs as well as associations between objective and patient-reported outcomes. Allowance has been made for incomplete data to ensure adequate statistical power for primary analyses.

Statistical Analysis Plan Data analysis will be conducted using established statistical software. Continuous variables will be assessed for normality and summarised using appropriate descriptive statistics. Associations between variables will be explored using correlation analyses, with parametric or non-parametric methods applied as appropriate. Comparative analyses may be performed for exploratory subgroup comparisons (e.g., return to sport categories or presence of pre-injury symptoms).

All analyses will be interpreted within the context of an observational study design, and findings will be considered hypothesis-generating.

Handling of Missing Data Missing data will be assessed to determine patterns and potential sources (e.g., non-response, incomplete testing). Where feasible, analyses will be conducted using available data without imputation. The extent and impact of missing data will be reported transparently, and sensitivity analyses may be undertaken if appropriate.

Study Oversight and Governance The study is conducted in accordance with Good Clinical Practice (GCP), the Declaration of Helsinki, and NHS research governance frameworks. All study personnel are trained in study procedures to ensure standardisation. Data handling complies with the UK General Data Protection Regulation (GDPR) and Data Protection Act 2018.

Inclusion Criteria:

Aged 18 years or older at the time of recruitment

• Have a confirmed diagnosis of Achilles tendon rupture, diagnosed clinically and recorded within the NHS clinical database
• Have been managed non-surgically using the SMART (Swansea Morriston Achilles Rupture Treatment) rehabilitation protocol
• Be between 12 and 15 months post-injury at the time of study assessment
• Be able and willing to provide written informed consent to participate in the study

Exclusion Criteria:

• Unable to provide informed consent
• Have previously undergone surgical repair of the Achilles tendon or experienced a re-rupture
• Have a neuromuscular or neurological condition that could affect lower limb strength or function
• Did not follow the SMART rehabilitation protocol for non-surgical management
• Have a history of Achilles tendinopathy or rupture in the contralateral (uninjured) limb
• Are unable to tolerate isokinetic strength testing due to pain, discomfort, or other medical reasons

Adults who previously sustained an Achilles tendon rupture and were treated non-surgically using the SMART rehabilitation protocol within Liverpool University Hospitals NHS Foundation Trust. Eligible participants are identified from an existing clinical database and represent patients 12-15 months post-injury who completed standard physiotherapy rehabilitation. All participants are drawn from routine NHS orthopaedic and physiotherapy services at Aintree and Broadgreen Hospitals.

Individual participant data will not be shared. Only aggregated, anonymised results will be published. This is consistent with participant consent and NHS data governance requirements