No Difference in Conversion Rate to Hip Arthroplasty After Intramedullary Nail or Sliding Hip Screw for Extracapsular Hip Fractures: An Observational Cohort Study of 19,604 Individuals

BACKGROUND: The widespread use of intramedullary nails (IMNs) compared with sliding hip screws (SHSs) in extracapsular hip fractures (AO/OTA 31-A1, 31-A2, 31-A3) has been questioned because of a higher complication rate, although the outcome might have improved through more recent implant designs and the learning curve. This study aimed to investigate if there is a difference with regard to the cumulative incidence of conversion to arthroplasty or any reoperation during the first 5 years after IMN or SHS fixation of extracapsular hip fractures.

METHODS: In this nationwide, observational cohort study, individuals who were ≥60 years of age and were registered in the Swedish Fracture Register (SFR) from 2012 to 2018 due to extracapsular fracture and were primarily treated with an IMN or SHS were followed in the SFR and the Swedish Arthroplasty Register (SAR) for a minimum of 1 year. The primary outcome was the cumulative incidence of conversion to arthroplasty (conversion rate). The secondary outcome was the cumulative incidence of all reoperations (reoperation rate). Both were calculated in a competing risk analysis during the first 5 years.

RESULTS: We included 19,604 individuals (70% women), with a median age of 85 years (range, 60 to 107 years). The 31-A2 fracture was most prevalent (52%), followed by the 31-A1 fracture (28%). No significant differences were seen in the 1-year conversion rate after IMN or SHS use (1.0% compared with 0.9% in the 31-A1 fractures, 1.7% compared with 1.3% in the 31-A2 fractures, and 1.3% compared with 1.5% in the 31-A3 fractures) or in the 1-year reoperation rate (1.9% compared with 1.9% in the type-A1 fractures, 3.4% compared with 2.5% in the type-A2 fractures, and 4.0% compared with 5.2% in the type-A3 fractures). Only in 31-A2 fractures were more reoperations seen after IMN use at 2 and 5 years (p < 0.05). The crude 1-year-mortality was 26.4% (5,178 of 19,604), without significant differences between implants.

CONCLUSIONS: Considering conversion arthroplasty, IMNs and SHSs performed equally well in general. IMN use was associated with more reoperations than SHS use in 31-A2 fractures at 2 years. However, from a clinical perspective, the differences between the implants were small, in particular when considering the competing risk of dying.

LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.