The epidemiology of Achilles tendon re-rupture and associated risk factors: male gender, younger age and traditional immobilising rehabilitation are risk factors.

purposeThe aim of this study was to describe the epidemiology of Achilles tendon re-rupture. Secondary aims were to identify factors predisposing to increased Achilles tendon re-rupture risk, at the time of primary Achilles tendon rupture.

methodsA retrospective review of all patients with primary Achilles tendon rupture and Achilles tendon re-rupture was undertaken. Two separate databases were compiled: the first included all Achilles tendon re-ruptures presenting during the study period and described epidemiology, mechanisms and nature of the re-rupture; the second was a case-control study analysing differences between patients with primary Achilles tendon rupture during the study period, who did, or did not, go on to develop re-rupture, with minimum review period of 1.5 years.

resultsSeven hundred and eighty-three patients (567 males, 216 females) attended with primary Achilles tendon rupture and 48 patients (41 males, 7 females) with Achilles tendon re-rupture. Median time to re-rupture was 98.5 days (IQR 82-122.5), but 8/48 re-ruptures occurred late (range 3 to 50 years) after primary Achilles tendon rupture. Males were affected more commonly (OR = 7.40, 95% CI 0.91-60.15; p = 0.034). Mean Achilles tendon re-rupture incidence was 0.94/100,000/year for all ages and 1.16/100,000/year for adults (≥ 18 years). Age distribution was bimodal for both primary Achilles tendon rupture and re-rupture, peaking in the fifth decade, with secondary peaks in older age. Incidence of re-rupture was higher in less socioeconomically deprived sub-populations (OR = 2.01, 95%CI 1.01-3.97, p = 0.04). The majority of re-ruptures were low-energy injuries. Greater risk of re-rupture was noted for patients with primary rupture aged < 45 years [adjusted odds ratio (aOR) 1.96; p = 0.037] and those treated with traditional cast immobilisation (aOR 2.20; p = 0.050).

conclusionThe epidemiology of Achilles tendon re-rupture is described and known trends (e.g. male predilection) are confirmed, while other novel findings are described, including incidence of a small but significant number of late re-ruptures, occurring years after the primary injury and an increased incidence of re-rupture in less socioeconomically deprived patients. Younger age and traditional immobilising cast treatment of primary Achilles tendon rupture were independently associated with Achilles tendon re-rupture. LEVEL OF EVIDENCE: III.