The Alpha-Defensin Prosthetic Joint Infection Test Has Poor Validity for Native Knee Joint Infection

BackgroundThe alpha-defensin test known as Synovaure has been very effective in diagnosis of prosthetic joint infections (PJIs). Being able to easily and accurately differentiate septic and inflammatory arthropathies in native joints would improve diagnostic workup and management. We tested the ability of an alpha-defensin test to distinguish septic from inflammatory or crystalline arthropathy in the native knee.Methods40 native knee joint fluid specimens were tested with cell count, fluid analysis, and culture and alpha-defensin testing. We determined the sensitivity and specificity of the alpha-defensin test using culture-positive fluid as the gold standard for septic arthropathy and positive crystals as the gold standard for crystalline arthropathy.ResultsThe Synovasure PJI test had 100% specificity for septic arthritis coupled with a 28% false-positive rate when applied to native knee aspirations. False-positive rate was 5.3 times higher in patients with crystals found in the joint fluid.ConclusionAlpha-defensin testing, in the form of the Synovasure PJI test, has a high-false-positive rate when used to distinguish septic and inflammatory arthritis in the native knee joint. Future work will need to determine the sensitivity and specificity of the newer native joint panel. Clinicians should be cognizant of the specific alpha-defensin test used when sampling native knee synovial fluid.     

Risk Factors and Effect of Acute Kidney Injury on Outcomes Following Total Hip and Knee Arthroplasty

BackgroundDevelopment of acute kidney injury (AKI) following primary total joint arthroplasty (TJA) is a potentially avoidable complication associated with negative outcomes including discharge to facilities and mortality. Few studies have identified modifiable risk factors or strategies that the surgeon may use to reduce this risk.MethodsWe identified all patients undergoing primary TJA at a single hospital from 2005 to 2017, and collected patient demographics, comorbidities, short-term outcomes, as well as perioperative laboratory results. We defined AKI as an increase in creatinine levels by 50% or 0.3 points. We compared demographics, comorbidities, and outcomes between patients who developed AKI and those who did not. Multivariate regressions identified the independent effect of AKI on outcomes. A stochastic gradient boosting model was constructed to predict AKI.ResultsIn total, 814 (3.9%) of 20,800 patients developed AKI. AKI independently increased length of stay by 0.26 days (95% confidence interval [CI] 0.14-0.38, P < .001), in-hospital complication risk (odds ratio = 1.73, 95% CI 1.45-2.07, P < .001), and discharge to facility risk (odds ratio = 1.26, 95% CI 1.05-1.53, P = .012). Forty-one predictive variables were included in the predictive model, with important potentially modifiable variables including body mass index, perioperative hemoglobin levels, surgery duration, and operative fluids administered. The final predictive model demonstrated excellent performance with a c-statistic of 0.967.ConclusionOur results confirm that AKI has adverse effects on outcome metrics including length of stay, discharge, and complications. Although many risk factors are nonmodifiable, maintaining adequate renal perfusion through optimizing preoperative hemoglobin, sufficient fluid resuscitation, and reducing blood loss, such as through the use of tranexamic acid, may aid in mitigating this risk.     

Is Preoperative Staphylococcus aureus Screening and Decolonization Effective at Reducing Surgical Site Infection in Patients Undergoing Orthopedic Surgery? A Systematic Review and Meta-Analysis With a Special Focus on Elective Total Joint Arthroplasty

BackgroundStaphylococcus aureus is a major pathogen implicated in orthopedic infections worldwide. Preoperative decolonization has been promoted but different strategies present mixed results. Thus, the goals of this study are to determine (1) whether S aureus screening and/or decolonization is effective at reducing surgical site infection in orthopedic surgery, (2) with a special focus on elective total joint arthroplasty (TJA), and (3) which preoperative S aureus screening/treatment strategy is most cost-effective for TJA.MethodsPubMed, Ovid MEDLINE, and Cochrane databases were searched on January 1, 2020, using a systematic strategy. We included papers with data comparing surgical site infection and periprosthetic joint infection rate in orthopedic surgery and/or elective total hip and knee arthroplasty patients before/after S aureus screening and/or decolonization protocol and papers evaluating the cost-effectiveness of different S aureus screening/treatment strategies.ResultsA total of 1260 papers were screened, and 32 papers were ultimately included. Results showed an increased risk of developing any infection (relative risk [RR] = 1.71 ± 0.16) and S aureus infection (RR = 2.79 ± 0.45) after orthopedic surgery without previous nares and whole-body decolonization. Focusing exclusively on elective TJA, there was an increased risk of developing any infection (RR = 1.70 ± 0.17) and S aureus infection (RR = 2.18 ± 0.41) if no decolonization is performed. All strategies appeared to be cost-effective, although universal decolonization without screening seemed to be the most advantageous.ConclusionPreoperative S aureus screening/decolonization protocol lowered the risk of infection after elective orthopedic and TJA surgeries. However, further studies are needed to determine optimal clinical and cost-effective methodologies.     

High Rates of Spacer Fracture in the Setting of Extended Trochanteric Osteotomy With a Specific Thin-Core Articulating Antibiotic Hip Spacer

BackgroundTwo-stage revision remains the standard of care for prosthetic joint infection after total hip arthroplasty. However, there are substantial complications associated with articulating antibiotic hip spacers. Handmade and molded spacers have been shown to have higher rates of spacer fracture than antibiotic-coated prostheses (ACPs). The aim of this study is to review outcomes with an implant that is often categorized as an ACP spacer, the Zimmer-Biomet StageOne Select Femoral Spacer (ZBSO).MethodsA retrospective review was performed of 63 patients who underwent placement of a ZBSO. Patients were compared based on whether or not an extended trochanteric osteotomy (ETO) was performed using Fisher’s exact and t-tests.ResultsFive patients were excluded due to lack of follow-up or death shortly after stage 1 surgery, leaving 58 patients. Spacer fracture was noted in 5 of 58 patients (8.6%). Sixteen patients underwent ETO and 25.0% suffered a spacer fracture compared to 2.3% without ETO (odds ratio 13.7, P = .0248). There was no association between patient demographics or ETO length and spacer fracture. Two patients had periprosthetic fractures (3.4%) and 4 had dislocations (6.9%). Forty-nine patients (84.4%) went on to second-stage revision; of those 26.5% failed to clear the infection and required an average of 2.2 additional surgeries.ConclusionThe ZBSO spacer has overall complication rates similar to previously reported spacer series. Although the ZBSO looks like an ACP spacer, in the setting of ETO, it behaves like a molded or handmade spacer with a high rate of spacer fracture (25%) due to the small diameter of the core. This implant should be used with caution in combination with an ETO.     

Neglected medial swivel dislocation of talonavicular joint with calcaneus,cuboid and 5th metatarsal fractures – A case report

Talonavicular dislocation is a rare injury. Isolated medial or lateral talonavicular dislocations without disruption of subtalar joint are known as medial or lateral swivel dislocations respectively, both being extremely rare. We describe a rare case of neglected medial swivel dislocation with concomitant calcaneus, cuboid and 5th metatarsal fracture, which was managed with open reduction and fixation of talonavicular joint with k-wires and an external distractor. At 1 year follow up the patient was mobilizing full weight bearing without any pain or deformity, the radiographs showing well located talonavicular joint and healed calcaneus, cuboid and 5th metatarsal fractures. This is the first reported case of medial swivel talonavicular dislocation with associated calcaneum, cuboid and 5th metatarsal fracture to the best of our knowledge. This case report highlights the importance of maintaining high level of suspicion for diagnosing midfoot injuries in a polytraumatized patient as well as need of accurate and timely reduction of dislocation for good functional outcome.Level of clinical evidenceLevel 4.     

Adverse events involving hallux metatarsophalangeal joint implants: Analysis of the United States Food and Drug Administration data from 2010 to 2018

BackgroundThe prevalence of osteoarthritis of the hallux metatarsophalangeal joint (MTPJ) is 1 in 40 people over the age of 50. Surgical treatment options for MTPJ arthritis include joint preservation, joint resurfacing, and arthrodesis. Hallux MTPJ implants have evolved over the past several decades, but are associated with various complications. The aim of this study was to examine the MAUDE database to determine reported adverse events for hallux MTPJ implants.Materials and methodsThe US Food and Drug Administration’s (FDA) Manufacturer and User Facility Device Experience (MAUDE) database was reviewed from 2010 to 2018 to review voluntary reported adverse event reports for approved implants within the United States. We recorded the type of adverse event and excluded duplicate reports and those extracted from already published literature.ResultsAmong 64 reported hallux MTPJ implant adverse events, the most common modes of adverse events were component loosening (34%), infection (14.1%), component fracture (9.4%), inflammation (9.4%), and allergic reaction (7.8%). Regarding implant type, Cartiva SCI had the highest percentage of adverse events (23.4%), followed by Arthrosurface ToeMotion (20.3%), Ascension MGT (12.5%), Arthrosurface HemiCAP® (10.9%), Futura primus (9.4%), and Osteomed Reflexion (6.3%). There was an increase in reported adverse events after 2016. The MAUDE database does not report the total incidence of implant insertion.ConclusionOur study of the MAUDE database demonstrated that component loosening and infection are the most common modes of adverse events for hallux MTPJ implants. Cartiva accounted for one-fourth of the implant-related adverse events during our study period, followed by ToeMotion, and Ascension MGT implants. Continued reporting of adverse events will improve our understanding on short and long-term complications of various hallux MTPJ implants.Level of evidenceLevel IV; Case Series from Large Database Analysis; Treatment Study.