The use of bone cement as a fixation agent has ensured the long-term functionality of THA implants 1. However, some studies have shown the undesirable effect of wear of stem-cement interface, due to the release of metals and polymeric debris lead to implant failure 2,3. Debris is generated by the micromotion together with a severely corrosive medium present in the crevice of stem-cement interface 3,4. FEA studies showed that micromotion can affect osseointegration and fretting wear 5,6. The aim of this research is to investigate if the micromotions measures from The For the computational analysis, the same testing configurations were modeled on software ANSYS. The analysis was performed using linear isotropic elasticity for both stem (E=193GPa; ⱱ=0.27; σy=400MPa) and PMMA cement (E=2.7GPa; ⱱ=0.35; σu=76MPa)7,8. A second-order tetrahedral element was used to mesh all components with a size of 0.5 mm in the stem-cement contact area, increasing until 1.0 mm outside from them. A frictional contact (µ=0.25) with an augmented Lagrange formulation was used. The third cycle of loading was evaluated and a variation of sliding distance less than 10% was set as convergence criteria. The micromotion was measured as the sliding distance on the stem-cement interface.Introduction
Methods
Antibiotic loaded spacers are often used during a two-stage exchange for periprosthetic joint infections (PJI) both for its mechanical properties and as a means for local antibiotic delivery. The main goal of this study is to compare the rate of positive cultures during reimplantation with the use of different antibiotic loaded spacers: aminoglycoside only vs. combined glycopeptide/aminoglycoside vs. combined glycopeptide/carbapenem/aminoglycoside. We retrospectively evaluated every two-stage exchange procedures for infected hip/knee arthroplasty between 2012–2018. Microbiological findings in the first and second stage were registered as well as the type of spacer and antibiotic(s) used. Cases in whom no cultures were obtained during reimplantation and cases without sufficient data on antibiotic(s) used in cement spacers were excluded.Aim
Method
Infection is a complication in hip arthroplasty. It increases mortality and morbidity and is a cause for patient's dissatisfaction. Previous Works report an infection rate between 0,4% e 1,5% in primary hip replacement and between 3,2% in revision hip replacement. The aim of this work was to access the infection rates in one hospital, compare them with the reported rates and investigate possible risk factors for infection. Electronic clinical records were consulted. Patients who underwent total hip arthroplasty (primary or revision) or hemiarthroplasty in one hospital, between the 1st February 2011 and 31st February 2013, were included. Two hundred and sixty one patients (267 surgeries) were included. Demographically, 57,5% were female patients and 42,5% were male patients with an average age of 77,1 years (± 12,3 years). Infection rate for hemiarthroplasty 3,1%, for primary total hip arthroplasty was 1,4% and for revision procedures 4,8%. A statistically significant relation was found between arthroplasty infection and superficial wound infection (p<0,001), wound dehiscence (p<0,001), and surgery performed during summer months (p<0,05) No relation was found with duration of the surgery or the hospital stay or the patient's comorbidities. The infection rate is similar to the rate reported in other clinical centres. Superficial wound complications are a good predictor for arthroplasty infection, so it is important to diagnose and start prompt appropriate management and vigilance. The increase in infection rates in summer months may be related to higher operating room temperature or less routined personal. We concluded, therefore, that infection is a complication in hip arthroplasty being prevention is a key feature when arthroplasty is performed, as well as clinical vigilance for infection signs.
