Improving the Endoprosthesis Design and the Postoperative Therapy as a Means of Reducing Complications Risks after Total Hip Arthroplasty

Prognostic Value of C-Reactive Protein in Primary Total Hip Arthroplasty

Background/Objectives: Periprosthetic joint infections (PJIs) are feared complications in arthroplasty and are associated with an increased mortality rate. PJI prevention is of paramount importance since treatment is difficult. In case of an infection, it is crucial to diagnose it at an early stage in order to initiate adequate therapy. The Musculoskeletal Infection Society (MSIS) proposed a catalog of different major and minor diagnostic criteria in 2011 to define a PJI. They were adapted in the following years. One of these criteria is the blood level of C-reactive protein (CRP). CRP is a non-specific acute-phase protein that also increases in response to various non-infectious inflammatory responses. CRP is also routinely obtained prior to total hip arthroplasty (THA) to screen for possible contraindications for arthroplasty such as an acute infection. The validity of this approach has rarely been investigated. The aim of this study was to evaluate the diagnostic value of perioperative CRP in patients receiving a THA. Methods: A total of 239 patients were included in this study and retrospectively analyzed. CRP values were obtained preoperatively and three values postoperatively. Sensitivity, specificity, area under the curve (AUC) and optimal thresholds were calculated. Results: In the whole group, 10 patients developed a PJI. No significance was demonstrated between patients without and with later PJI in terms of preoperative CRP (p = 0.182), postoperative CRP (p = 0.167), relative CRP increase (p = 0.684) and respective CRP differences (p = 0.456). We were not able to find cut-off values with adequate sensitivity and specificity. Conclusions: Perioperative CRP values do not seem to be helpful in predicting further PJI. Rather, they should be used as a screening tool to detect ongoing infections in the individual patient prior to THA. This trial should encourage studies with more statistical power due to the small effect sizes.

Performance of textured dual mobility total hip prosthesis with a concave dimple during Muslim prayer movements

The single mobility bearing as a previous bearing design of total hip prosthesis has severe mobility constraints that can result in dislocation during Muslim (people who follow the Islam as religion) prayer movements, specifically shalat that requires intense movement. There are five intense movements (i.e., bowing, prostration, sitting, transition from standing to prostration, and final sitting) during Muslim prayer that may generate an impingement problem for patients with total hip prosthesis. In this work, textured dual mobility total hip prosthesis with two textured cases (i.e., textured femoral head and textured inner liner) are presented and their performances are numerically evaluated against untextured surface model during Muslim prayer movement. The concave dimple design is chosen for surface texturing, while for simulating femoral head materials, SS 316L and CoCrMo is choosen. To represent the real condition, three-dimensional computational fluid dynamics (CFD) coupled with two-way fluid-structure interaction (FSI) methods are employed to analyze elastohydrodynamic lubrication problem with non-Newtonian synovial fluid model. The main aim of the present study is to investigate the tribological performance on dual mobility total hip prosthesis with applied textured surface with concave dimple in femoral head and inner liner surface under Muslim prayer movements. It is found that applying surface texturing has a beneficial effect on the lubrication performance for some intense movements. The textured femoral head model performs better than textured inner liner model and untextured model (both femoral head and inner liner). The numerical results also indicate superior performance of CoCrMo femoral head compared to SS 316L femoral head. These findings can be used as a reference for biomedical engineers and orthopedic surgeons in designing and choosing suitable total hip prosthesis for Muslims makes they can carry out Muslim prayer movements like humans in general who have normal hip joints.