Differences in risk factors exist for the occurrence of bilateral versus unilateral distal biceps tendon ruptures: a systematic review

Importance Distal biceps rupture is a debilitating injury that is increasing in incidence. A subset of patient experiences this injury on both sides, simultaneously or at separated times. Previous studies have evaluated the incidence and risk factors of unilateral distal biceps rupture. However, little is known about the risk factors for bilateral distal biceps rupture. Aims This aims of this study were to determine risk factors for bilateral distal biceps rupture and to compare these to the known risk factors for unilateral rupture. Evidence review A systematic review of literature was conducted using five databases, producing a total of 1183 papers. After the review process, 31 papers with data bilateral distal biceps tendon ruptures were included. Findings The 31 papers included a total of 2234 patients with 2366 ruptures. Patients with a bilateral rupture were younger than patients with unilateral ruptures (45.8 vs 48.8 years old). Women made up a larger percentage of patients with bilateral ruptures (6.8% vs 4.0%). Bilateral injuries occurred most commonly during heavy lifting or falls, whereas forced extension of the arm was the most frequently reported injury mechanism reported with unilateral ruptures. Tobacco used was more common in patients with bilateral ruptures (24.4% vs 6.8%). Labour-intensive occupations and anabolic steroid use did not appear to increase the risk of a bilateral rupture. Pooling of the data was not possible due to heterogeneity of the included studies. Conclusions While differences in risk factors between patients with unilateral and bilateral ruptures were observed, there was too great of a degree of heterogeneity among the studies to perform a meta-analysis of the data. Level of evidence Systematic review; level III evidence.