Predictors of Clinical Outcome After Acute Achilles Tendon Ruptures

Background: In patients with an acute Achilles tendon rupture, it has not been possible to determine the superiority of a single specific treatment modality over other treatments with respect to symptoms and function. When several pertinent treatment protocols are available for an injury, it is of interest to understand how other variables, such as age, sex, or physical activity level, affect outcome to better individualize the treatment. Purpose: To investigate predictors of both symptomatic and functional outcomes after an acute Achilles tendon rupture. Study Design: Cohort study (Prognosis); Level of evidence, 2. Methods: Ninety-three patients (79 men and 14 women; mean age, 40 years) were evaluated prospectively at 3, 6, and 12 months. The main outcome measures in this study were the Achilles tendon Total Rupture Score (ATRS) for symptoms and maximum heel-rise height for function. The independent variables evaluated as possible predictors of outcome included treatment, sex, age, body mass index (BMI), physical activity level, symptoms, and quality of life. Results: Treatment, age, BMI, physical activity level, heel-rise height at 6 months, and the ATRS at 3 months were eligible for further analysis. Only male sex was included for the prediction models. The 4 different multiple linear regression models (predicting the ATRS at 6 and 12 months and heel-rise height at 6 and 12 months) were significant (P < .001-.002), and the R-2 values for the models were 0.222 to 0.409. Surgical or nonsurgical treatment is a moderate predictor of symptoms and a weak predictor of heel-rise height after an acute Achilles tendon rupture. At the 6-month follow-up, surgical treatment was associated with a larger heel-rise height, but the opposite was seen at 12 months. Surgical treatment resulted in a lower degree of symptoms. Increasing age was a strong predictor of reduced heel-rise height, and an increase in age of 10 years reduced the expected heel-rise height by approximately 8%. A higher BMI was also a strong predictor of a greater degree of symptoms, and a 5-unit higher BMI predicted a reduction of approximately 10 points in the ATRS. Conclusion: The present study identified important possible predictors of outcome. Despite having a wide range of clinically relevant variables, the models had a limited ability to predict the final individual outcome. In general, the models appear to be better at predicting function than symptoms.