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.
Study Type
OBSERVATIONAL
Enrollment
115
Participants previously received standard non-surgical treatment for Achilles tendon rupture following the SMART (Swansea Morriston Achilles Rupture Treatment) functional rehabilitation protocol as part of routine NHS care. No interventions are assigned as part of this study; all data are collected at a single follow-up visit.
Broadgreen Hospital Physiotherapy department
Liverpool, Merseyside, United Kingdom
RECRUITINGAintree University Hospital Therapies department
Liverpool, Merseyside, United Kingdom
RECRUITINGIsokinetic plantarflexor strength - Peak Torque
Peak plantarflexion torque will be measured using isokinetic dynamometry. Peak torque (Newton metres \[Nm\]) represents the maximum force generated by the plantarflexor muscles during a maximal voluntary contraction. Unit of Measure: Newton metres (Nm) Minimum value: 0 Nm Maximum value: No fixed maximum value Higher values indicate: Greater plantarflexor muscle strength (better outcome)
Time frame: 12-15 months post-injury (single study visit)
Isokinetic Plantarflexion Strength Normalised to Body Weight
Peak plantarflexion torque normalised to body weight, measured using isokinetic dynamometry. Results are expressed as Newton metres per kilogram (Nm/kg) to facilitate comparison of plantarflexor muscle strength between individuals of different body sizes. Unit of Measure: Newton metres per kilogram (Nm/kg) Minimum Value: 0 Nm/kg Maximum Value: No fixed maximum value Higher values indicate: Greater plantarflexor muscle strength relative to body weight (better outcome)
Time frame: 12-15 months post injury
Isokinetic Plantarflexion Strength Limb Symmetry Index (LSI)
Limb Symmetry Index (LSI) for isokinetic plantarflexion strength. LSI is calculated as the peak torque of the injured limb divided by the peak torque of the uninjured limb and expressed as a percentage. An LSI of 100% indicates equal strength between limbs, while values below 100% indicate a strength deficit in the injured limb. Unit of Measure: Percent (%) Minimum Value: 0% Maximum Value: No fixed maximum value Higher values indicate: Greater symmetry between injured and uninjured limbs and therefore a better outcome.
Time frame: 12-15 months post injury
Achilles Tendon Total Rupture Score
The Achilles Tendon Total Rupture Score (ATRS) is a validated patient-reported outcome measure assessing symptoms, physical activity, and functional limitations following Achilles tendon rupture. Scores range from 0 to 100, with higher scores indicating better perceived recovery and fewer symptoms. Time Frame: 12-15 months post-injury (single study visit) Unit of Measure: Points Minimum Value: 0 Maximum Value: 100 Higher scores indicate: Better outcome (fewer symptoms and greater function) Lower scores indicate: Worse outcome (more symptoms and greater functional limitation)
Time frame: 12-15 months post-injury (single study visit)
Correlation Between Achilles Tendon Total Rupture Score and Peak Plantarflexion Torque
Correlation between subjective recovery measured by the Achilles Tendon Total Rupture Score (ATRS) and objective plantarflexor muscle strength measured as peak plantarflexion torque during isokinetic dynamometry. Unit of Measure: Correlation coefficient (r) Minimum Value: -1 Maximum Value: 1 Interpretation: Values closer to ±1 indicate a stronger relationship between ATRS and peak plantarflexion torque. Values closer to 0 indicate a weaker relationship.
Time frame: 12-15 months post injury
Correlation Between Achilles Tendon Total Rupture Score and Plantarflexion Strength Limb Symmetry Index
Correlation between subjective recovery measured by the Achilles Tendon Total Rupture Score (ATRS) and objective plantarflexion strength symmetry measured using the Limb Symmetry Index (LSI). Time Frame: 12-15 months post-injury (single study visit) Unit of Measure: Correlation coefficient (r) Minimum Value: -1 Maximum Value: 1 Interpretation: Values closer to ±1 indicate a stronger relationship between ATRS and Limb Symmetry Index. Values closer to 0 indicate a weaker relationship.
Time frame: 12-15 months post injury
Health-related quality of life - EuroQol Five-Dimension Five-Level Questionnaire (EQ-5D-5L) Summed Dimension Score
Health-related quality of life will be assessed using the EuroQol 5-Dimension, 5-Level (EQ-5D-5L) Questionnaire. The EuroQol Five-Dimension Five-Level Questionnaire (EQ-5D-5L) is a patient-reported measure of health-related quality of life consisting of five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is rated on a five-level scale from no problems to extreme problems. Minimum value: 5 Maximum value: 25 Direction of scale: Lower scores indicate a better outcome (fewer health problems); higher scores indicate a worse outcome (more severe health problems).
Time frame: 12-15 months post injury
Health related quality of life - EuroQol Visual Analogue Scale
The EuroQol Visual Analogue Scale (EQ VAS) is a self-reported measure of overall health status. Participants rate their current health on a vertical visual analogue scale ranging from 0 ("the worst health you can imagine") to 100 ("the best health you can imagine"). Minimum value: 0 Maximum value: 100 Higher scores indicate: Better self-rated health status Lower scores indicate: Worse self-rated health status
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Time frame: 12-15 months post injury
Achilles Tendon Resting Angle (ATRA)
The Achilles Tendon Resting Angle (ATRA) is a goniometric measure used as an indirect assessment of Achilles tendon elongation. Side-to-side difference in ATRA between the injured and uninjured limbs will be measured in degrees. ATRA does not have fixed minimum or maximum possible values. Higher values indicate less tendon elongation (better outcome), while lower values indicate greater tendon elongation (worse outcome). Time Frame: 12-15 months post-injury (single study visit) Unit of Measure: Degrees (°) Minimum Value: No fixed minimum value Maximum Value: No fixed maximum value Higher values indicate: Less tendon elongation (better outcome) Lower values indicate: Greater tendon elongation (worse outcome)
Time frame: 12-15 months post injury
Return to sport/activity status
Return to sport/activity status assessed at follow-up. Participants will be categorised according to their highest level of return to pre-injury sport or physical activity: Return to same level and frequency Return to same level at reduced frequency Return to a lower level No return to sport/activity Time Frame: 12-15 months post-injury (single study visit) Unit of Measure: Category Minimum Value: No return to sport/activity Maximum Value: Return to same level and frequency Higher categories indicate: Greater return to pre-injury sport/activity participation (better outcome)
Time frame: 12-15 months post injury
Presence of Pre-Injury Achilles Tendon Symptoms
Description: Presence of Achilles tendon pain or symptoms prior to tendon rupture, assessed by participant self-report. Participants will be classified according to whether Achilles tendon symptoms were present before the rupture. Time Frame: Assessed at 12-15 months post-injury (single study visit; recall of pre-injury symptoms) Unit of Measure: Category Categories: No pre-injury Achilles symptoms Pre-injury Achilles symptoms present Interpretation: Presence of pre-injury symptoms may indicate preceding Achilles tendon pathology.
Time frame: 12-15 months post injury