The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI. A retrospective review was conducted to assess the accuracy of different marker combinations for diagnosing chronic PJI. A total of 573 patients were included in the study, of which 124 knees and 122 hips had a diagnosis of chronic PJI. Complete blood count and synovial fluid analysis were collected. Recently published blood cell ratio cut-off points were applied to receiver operating characteristic curves for all markers and combinations. The area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values were calculated.Aims
Methods
In England and Wales in 2012 over 160,000 primary total hip and knee replacements were performed with 57% of hip replacements utilising uncemented prostheses. The main cause of failure, affecting approximately 10% of patients, is aseptic loosening. Previous research has found that functionalising titanium with lysophosphatidic acid (LPA) induces an increase in human osteoblast maturation on the implant surface through co-operation with active metabolites of vitamin D3. This feature, the small size of the LPS molecule and its affinity to readily bind to titanium and hydroxylapatite makes it an especially desirable molecule for bone biomaterials. Nevertheless biomaterials that also demonstrate anti-microbial properties are highly desirable. To test the antimicrobial efficacy of the LPA-functionalised titanium, a clinical isolate of 500nM to 1μM LPA were the optimum concentrations to significantly inhibit bacterial adhesion (ANOVA, p<0.001). These concentrations also reduced biofilm mass on the surface of the titanium. Proteomic analysis highlighted an increase in low molecular weight proteins as a result of optimal LPA surface concentrations. Fatty acid chains as found in LPA have previously been associated with causing leakage of low molecular weight proteins through increased cell membrane permeability. LPA coatings have the potential to enhance implant osseointegration whilst simultaneously reducing bacterial attachment. This technology may reduce both septic and aseptic failure of cementless joint prostheses, ultimately prolonging implant longevity and patient quality of life.
