[Minimizing risk: evaluation of the relationship between femoral stem loosening and the risk of presenting with peri-prosthetic hip fracture].

Abstract

Introduction: evaluation of predictors of periprosthetic fracture in loosened femoral stems.

Material and methods: retrospective case-control study comparing aseptic loosened stems in two groups: cases: patients who experienced periprosthetic femoral fracture before replacement could be performed (n = 9). Controls: experienced prosthetic replacement without fracture (n = 19).

Results: pain intensity (VAS) was the most important aspect (p = 0.01), predominating in the controls. The simple radiological parameters did not show statistically significant findings predictive of peri-prosthetic fracture (number of Gruen zones, sum of them in mm, stress shielding, pedestal, polyethylene wear, stem subsidence). The role of complementary tests (CT and scintigraphy) for the definitive diagnosis of loosening was relevant, but not significant. The type of implant showed no differences. Overall implant survival was higher in cases than in controls (p = 0.016). This difference continues when comparing each loosened stem until fracture or replacement (p = 0.024).

Conclusion: the main factor protecting against fracture is the replacement of a stem with clinical and radiological diagnosis of loosening. Adequate follow-up of the patient plays a determining role in this, especially when considering the greater intensity of pain in the controls, which used to guide surgeons to perform replacements before the fracture occurred. This is reinforced if we take into account that up to one third of the cases did not have regular check-ups, and therefore did not have the opportunity for replacement prior to the fracture. The role of complementary tests (CT and scintigraphy) is also very important, taking into account the low diagnostic yield obtained from simple X-rays.