Short proximal components in modular revision stems carry a higher risk for stem fractures

Abstract

Introduction: Fractures of modular hip revision stems are not uncommon. The current study examined implant-related factors on stem fracture. We hypothesised that in a modular stem the fracture risk is increased with the use of a short proximal implant component. Materials and methods: Anonymised data of all 32 patients in Switzerland with a Revitan modular hip system who had a stem fracture were obtained from the manufacturer. Implant and patient data were compared with all components implanted in Switzerland during the same time interval. Results: Between 2002 and 2017, 4834 Revitan stems were implanted, of which 32 fractured. A smaller size of the proximal stem component was significantly associated with a higher fracture risk ( p < 0.001). Compared with the control group, the proportion of male patients was higher among the fracture cases, patients were younger, and they had a higher body weight ( p < 0.001, respectively). Conclusions: The present study suggests that small proximal stem components increase the load at the modular junction due to size and lack of bony support. Surgeons should therefore avoid short proximal components so that the mid-stem junction lies as distally as possible and the risk of fracture is minimised.