Study design, participants, and inclusion and exclusion criteria
The present study is a single-centred retrospective review that was approved by the Institutional Board Review (Protocol number ID 05-61-57). Hip fracture patients who underwent CHA during a 4-year period (between January 2015 and December 2018) were identified and reviewed from the hospital electronic records. The inclusion criteria were patients who had 1) sustained low energy trauma and been diagnosed with femoral neck fractures and 2) underwent cemented hip replacement. The exclusion criteria were patients who had 1) multiple fractures or poly traumatized injury, 2) revision surgery and 3) pathological fracture other than osteoporosis hip fracture, such as metastatic fracture.
Perioperative protocol, surgical procedure and implant selection
All patients had received the same preoperative protocol with routine deep vein thrombosis (DVT) screening with doppler ultrasonography (13). In cases where patients had unexplainable dyspnoea with hypoxemia that was clinically suspicious for pulmonary embolism (PE), computer tomography angiography (CTA) was performed. In case of positive DVT finding, the patient would receive anti-coagulant injection for 2 weeks prior to definitive operation and then continue as oral anti-coagulant for total 3-months duration. The anaesthetic technique, either general or regional anaesthesia, was based on the decision of the respective anaesthesiologists. The surgical approach was an anterolateral approach with anterior hemimyotomy of the gluteus medius, in the lateral decubitus position. The type of operation, either cemented bipolar hip arthroplasty (BHA) or hybrid total hip replacement (THA), and the type of femoral stem were selected according to the respective surgeons’ preferences. For THA, the patients all received cementless acetabulum cup combined with cemented femoral stem. The cemented femoral stem choices in our institution included cemented Corail stem (DePuy International, Leeds, UK), C-stem (DePuy International, Leeds, UK), CPT stem (Zimmer Biomet, Warsaw, IN) and Exeter stem (Stryker Howmedica Osteonics, Mahwah, NJ). All polymethylmethacrylate (PMMA) bone cement used in this study was high-viscosity PALACOSâ bone cement (Heraeus Medical LLC, Yardley, PA). Our routine cementing technique was done in the following steps: 1) inform the anaesthesiologist for the cementation during the brushing and drying of the femoral canal, 2) manually mix the cement according to the manufacturer’s instruction, 3) insert an intramedullary cement restrictor plug 2 cm below the tip of the femoral stem, 4) use the distal suction catheter on the top of the intramedullary plug and pull the catheter out as soon as it is blocked with cement, 5) insert cement with finger-packed technique, at 2 minutes after cement mixing, without proximal pressurization, and 6) insert femoral stem with distal centralizer (except for the cemented Corail stem which did not require distal centralizer) and wait for the hardening of cement.
Data collection and outcome measurement
The charts were reviewed, using the electronic hospital database, to obtain the required data, including demographic data, perioperative data and postoperative data. The following demographic data were collected: age, gender, body mass index (BMI), ASA physical status (14), comorbid disease, time to surgery, preinjury ambulatory status, anti-platelet and anti-coagulant medication use, and preoperative laboratory values, such as haemoglobin (Hb) level, platelet count, glomerular infiltration rate (GFR) and albumin level. The time to surgery defined as the duration between the day of injury (fracture occurred) and the operative day. Preinjury ambulatory status was classified into 3 groups: ambulatory, ambulatory with assistance and non-ambulatory. Ambulatory was defined as independent ambulation. Ambulatory with assistance was defined as requiring assistance, such as with a cane or walker, for ambulation. Non-ambulatory was defined as a composite of wheelchair and bedridden status (15).
Perioperative data—including type of anaesthesia, operative time, estimated blood loss, intraoperative findings related to BCIS and BCIS grading, and packed red cell (PRC) transfusion—were reviewed and recorded by one author (SP), an anaesthesiologist who was not involved in the data analysis. BCIS was defined as sudden hypoxia, hypotension, cardiac arrhythmia and sudden cardiac arrest at the time of the cement insertion. BCIS grading was classified according to the classification system proposed by Donaldson (1) (Table 1). Each patient was classified as having no BCIS (grade 0), or BCIS grade 1, 2 or 3, depending on the severity of hypotension, oxygen desaturation, degree of consciousness and cardiovascular collapse status. Femoral stem was classified in 2 types according to the classification proposed by Shen (16): shape-closed type (large stem geometry that fully occupies the medullary canal) and forced-closed type (small taper design that allows the subsidence of the femoral stem in the cement mantle). Therefore, in our study, the cemented Corail stem was classified as shape-closed type, while the C-stem, CPT stem and Exeter stem were all classified as force-closed type.
Postoperative data—including major perioperative complications, in-hospital death during admission, and the death within 1 year postoperatively—were collected via chart review and telephone interview. The major perioperative complications were defined as follows: 1) cardiac complication requiring inotropic drug and admittance into coronary care unit, 2) pulmonary complication requiring ventilator support, 3) renal complication requiring peritoneal or haemodialysis, 4) infection requiring intravenous antibiotic treatment, and 5) symptomatic thromboembolic complication (acute stroke, symptomatic DVT or symptomatic pulmonary embolism).
MedCalc software version 15.8 was used to analyse the data. Normally distributed continuous data were presented as mean and standard deviation and compared with Student t-test, while non-normally distributed continuous data were presented as median and interquartile range. Categorical data were presented as proportion of cases and compared with Fisher’s exact test or Chi-square test as appropriate. All patients were allocated into 2 groups based on BCIS grading: Group A (BCIS grade 0 or 1: BCIS-Gr0/1) and Group B (BCIS grade 2 or 3: BCIS-Gr2/3). Risk factors for BCIS-Gr2/3 were compared between both groups. Univariate logistic regression analysis was used to evaluate the association between risk factors and BCIS-Gr2/3, and the predictive factors with values of p£0.10 were calculated by multivariate logistic regression analysis. Significance was defined as values of p<0.05.