Introduction

A displaced intracapsular fracture of the femur in an eldery patient is a potential life-threathening injury, and is usually treated with a partial or total arthroplasty\cite{van2013}.
The ideal mode of fixation of the implant is still under debate. Registry data shows an increased mortality risk for cemented fixation on the first 24h after surgery \cite{Kristensen_2020} , but the difference ceased to exist at the 30-day and 1 year evaluations \cite{Talsnes_2013}\cite{Parker2020}. Other review  \cite{Nantha2020}  found that cemented implants are associated with a lower risk of periprosthetic fractures. A pooled analisys of recent randomized trials found no significant difference in the number of general and local complications, when comparing methods of femoral stem fixation \cite{Veldman2017}.
Other authors argue that perioperative deaths were associated with advanced age and comorbidities, not with the type of fixation \cite{Hossain_2012} \cite{Dale_2019}.
To complement the evidence avaliable on this topic, we conducted a prospective evaluation of patients operated in our centre with a partial or total hip arthroplasty for a displaced femoral neck fracture.
The purpose of this study was to evaluate the effect of the femoral stem fixation (cemented versus uncemented) on mortality and complications rate. 

Patients and Methods

Since June 2015 we maintain a prospective database of all the patients operated at our institution for proximal femoral fractures. From this database we collected all the cases of total hip replacement and hemiartroplasty for femoral neck fractures operated between June 2015 and June 2019.
Patients with fractures secondary to malignancy, high energy trauma or cases in which a monobloc stem was used were excluded. Patients treated with fracture fixation were also excluded from this study.
The study outcomes were identified using information from the department database, from patient's hospital records, from the nationwide Health Data Platform (Plataforma de Dados da Saúde, PDS) and from the nationwide System for Electronic Notification of Deaths (Sistema Informático de Comunicação de Óbitos, SICO). Using these overlapping sources is possible to evaluate outcomes even if the patient received further treatment at other institutions and to know the date of death even if the patient was deceased outside our institution.
For each patient we collected information on demographical data (gender, date of birth, Body Mass Index) clinical data ( date of surgery, delay from admission to surgery, Charlston Comorbidity Index, type of femoral fixation and implant used)  and follow-up data ( mortality during inpatient stay, at 30, 90 and 365 days, implant-related complications to date, patient-related complications at 30 days).
In each case the method of femoral fixation was decided at the time of surgery, by the senior attending surgeon. The cemented implant used was the stainless steel, polished CORAIL stem (Depuy Synthes, Leeds, UK) with a contemporary cementation technique, the uncemented implant used was the titanium alloy, hydroxyapatite-coated CORAIL stem (Depuy Synthes, Leeds, UK).
Using a recent multicentric study \cite{Richardson_2020} as reference for one-year mortality for different types of fixation, we calculated that a total sample size of 408 patients is required, in order to have an 80% power at  a significance level of 0.05
Using a recent randomized controlled trial \cite{Inngul2015} as a reference for complication rates, we calculated that a minimum of 121 patients per group is required, in order to have an 80% power at  a significance level of 0.05 
Quantitative variables were evaluated for skewness and distribution and qualitative variables were grouped according to clinical relevance.
Univariate and multivariate logistic regression was used to test for associations between procedure and studied outcomes. Chi-squared test and Student's t-test were used to assess confounding variables.
Patients with incomplete data were excluded from the analysis.

Results

A total of 543 patients were operated in our institution for fractures of the femoral neck during the study period. we excluded Y patients for the reasons stated above (35 fracture fixation, 2 femoral head resection, 44 monobloc implant). The final number of patients with complete data was 462, from these U had cemented fixation and Y uncemented fixation.
 

Discussion

Patients with a fracture of the femoral neck following low-energy trauma have an increased risk for mortality when compared to the general population \cite{Abrahamsen_2009}.