VOL. 98-B, No. 12, DECEMBER 2016 1635  FOOT AND ANKLE Ageing, deep vein thrombosis and male gender predict poor outcome after acute Achilles tendon rupture E. Domeij-Arverud, P. Anundsson, E. Hardell, G. Barreng, G. Edman, A. Latifi, F. Labruto, P. W. Ackermann From Karolinska Institutet, Stockholm, Sweden  E. Domeij-Arverud, MD, PhD, Orthopaedic Surgeon, Institution of Molecular Medicine and Surgery Karolinska Institutet, Department of Orthopaedics, Danderyd Hospital, Stockholm, Sweden.  P. Anundsson, MD, House Officer, Institution of Molecular Medicine and Surgery Karolinska Institutet, Department of Orthopaedics, Stockholm, Sweden.  E. Hardell, Physiotherapist, Institution of Molecular Medicine and Surgery  G. Barreng, Physiotherapist, Institution of Molecular Medicine and Surgery Karolinska Institutet, Capio Artro Clinic, Stockholm, Sweden.  G. Edman, PhD, Psychiatrist, Department of Psychiatry Karolinska Institutet, Tiohunder Hospital, Norrtälje, Sweden.  A. Latifi, PhD, Ultrasonographer, Institution of Molecular Medicine and Surgery  F. Labruto, MD, PhD, Radiologist, Institution of Molecular Medicine and Surgery Karolinska Institutet, Section of Diagnostic Imaging, Karolinska University Hospital, Stockholm, Sweden.  P. W. Ackermann, Senior Lecturer, Associate Professor , Orthopaedic Surgeon, Institution of Molecular Medicine and Surgery Karolinska Institutet, Department of Orthopaedics, Karolinska University Hospital, Stockholm, Sweden. Correspondence should be sent to E. Domeij-Arverud; email: Erica.domeij-arverud@ds.se ©2016 The British Editorial Society of Bone & Joint Surgery doi:10.1302/0301-620X.98B12. BJJ-2016-0008.R1 $2.00 Bone Joint J 2016;98-B:1635–41. Received 23 August 2016; Accepted after revision 11 March 2016 Aims Patients with an acute Achilles tendon rupture (ATR) take a long time to heal, have a high incidence of deep vein thrombosis (DVT) and widely variable functional outcomes. This variation in outcome may be explained by a lack of knowledge of adverse factors, and a subsequent shortage of appropriate interventions. Patients and Methods A total of 111 patients (95 men, 16 women; mean age 40.3, standard deviation 8.4) with an acute total ATR were prospectively assessed. At one year post-operatively a uniform outcome score, Achilles Combined Outcome Score (ACOS), was obtained by combining three validated, independent, outcome measures: Achilles tendon Total Rupture Score, heel- rise height test, and limb symmetry heel-rise height. Predictors of ACOS included treatment; gender; age; smoking; body mass index; time to surgery; physical activity level pre- and post-injury; symptoms; quality of life and incidence of DVT. Results There were three independent variables that correlated significantly with the dichotomised outcome score (ACOS), while there was no correlation with other factors. An age of less than 40 years old was the strongest independent predictor of a good outcome one year after ATR (odds ratio (OR) 0.20, 95% confidence interval (CI) 0.08 to 0.51), followed by female gender (OR) 4.18, 95% CI 1.01 to 17.24). Notably, patients who did not have a DVT while immobilised post-operatively had a better outcome (OR 0.31, 95% CI 0.12 to 0.80). Conclusion Over the age of 40 years, male gender and having a DVT while immobilised are independent negative predictors of outcome in patients with an acute ATR. Cite this article: Bone Joint J 2016;98-B:1635–41. Healing of an acute Achilles tendon rupture (ATR) is a prolonged process. There is a wide variation in outcome between patients: some may have major functional deficits. 1-5 Current meta-analyses of the outcome of ATR have compared operative and non- operative treatment, and have not shown that one method is better than the other when the patient is mobilised early. 6 There is a lack of information about other factors which affect outcome. In 2014, Olsson et al 7 described how patient characteristics affected the outcome in men and found that older age was a strong predictor of reduced function. In an earlier paper they had reported substantially impaired function one year after surgery, add- ing that gender, pain, and physical activity during rehabilitation were important factors that contributed to the outcome. 8 However, under-representation of female patients made it difficult to evaluate the importance of gen- der on outcome. The reason for the variability in outcome is still unknown. A rate of deep vein thrombosis (DVT) of between 36% and 50%, irrespective of operative or non-operative treatment, has been reported in patients after ATR. 9-11 For this study, we hypothesised that DVT and gender, as well as multiple variables including age, body mass index (BMI), treat- ment, physical activity score and smoking, would influence the outcome of ATR. The aim of this observational cohort study was to assess the intrinsic and extrinsic fac- tors which could predict the combined objec- tive and subjective outcome one year after ATR.