Aim

A growing number of recent investigations on the human genome, gut microbiome, and proteomics suggests that the loss of mucosal barrier function, particularly in the gastrointestinal tract, may substantially affect antigen trafficking, ultimately influencing the close bidirectional interaction between the gut microbiome and the immune system. This cross-talk is highly influential in shaping the host immune system function and ultimately shifting genetic predisposition to clinical outcome. Therefore, we hypothesized that a similar interaction could affect the occurrence of acute and chronic periprosthetic joint infections (PJI).

Aim

The efficacy of various irrigation solutions in removing microbial contamination of a surgical wound and reducing the rate of subsequent surgical site infection (SSI), has been demonstrated extensively. However, it is not known if irrigation solutions have any activity against established biofilm. This issue is pertinent as successful management of patients with periprosthetic joint infection (PJI) includes the ability to remove biofilm established on the surface of implants and necrotic tissues. The purpose of this study was to evaluate the efficacy of various irrigation solutions in eradicating established biofilm, as opposed to planktonic bacteria, in a validated in vitro model.

Aim

Surgical management of PJI remains challenging with patients failing treatment despite the best efforts. An important question is whether these later failures reflect reinfection or the persistence of infection. Proponents of reinfection believe hosts are vulnerable to developing infection and new organisms emerge. The alternative hypothesis is that later failure is a result of an organism that was present in the joint but was not picked up by initial culture or was not a pathogen initially but became so under antibiotic pressure. This multicenter study explores the above dilemma. Utilizing next-generation sequencing (NGS), we hypothesize that failures after two-stage exchange arthroplasty can be caused by an organism that was present at the time of initial surgery but not isolated by culture.

Aim

While metagenomic (microbial DNA) sequencing technologies can detect the presence of microbes in a clinical sample, it is unknown whether this signal represents dead or live organisms. Metatranscriptomics (sequencing of RNA) offers the potential to detect transcriptionally “active” organisms within a microbial community, and map expressed genes to functional pathways of interest (e.g. antibiotic resistance). We used this approach to evaluate the utility of metatrancriptomics to diagnose PJI and predict antibiotic resistance.

Aim

The clinical relevance of microbial DNA detected via next-generation sequencing (NGS) remains unknown. This multicenter study was conceived to: 1) identify species on NGS that may predict periprosthetic joint infection (PJI), then 2) build a predictive model for PJI in a developmental cohort, and 3) validate predictive utility of the model in a separate multi-institutional cohort.

Aim

Microbial identification in the setting of periprosthetic joint infections (PJI) is crucial to tailor the best combination of surgical and medical treatment. Given the high cost, low sensitivity and slow results associated with traditional cultures, s synovial fluid antibody assay was developed. We asked whether antibody testing may be used as a proxy to traditional culture in the setting of PJI.

Aim

A large body of evidence is emerging to implicate that dysregulation of the gut microbiome (dysbiosis) increases the risk of surgical site infections. Gut dysbiosis is known to occur in patients with inflammatory bowel disease (IBD), allowing for translocation of bacteria across the inflamed and highly permeable intestinal mucosal wall. The null hypothesis was that IBD was not associated with increased risk of periprosthetic joint infection (PJI) after primary total hip and knee arthroplasty. Our aim was to investigate whether a prior diagnosis of IBD was associated with a higher risk of PJI following primary total hip and knee arthroplasty.

Aim

It is traditionally stated that around 80% of all periprosthetic joint infections (PJI) are caused by well-known gram-positive organisms such as Staphylococcus aureus. With the advances in diagnostic modalities and improved abilities to isolate infective organisms, we believe the organism profile causing PJI has changed over time and includes numerous other organisms that were either not recognized as pathogens and/or considered as contaminants.

Aim

D-dimer is a widely available serum test that detects fibrinolytic activities that occur during infection. Prior studies have explored its utility for diagnosis of chronic periprosthetic joint infections (PJI), but not explored its prognostic value for prediction of subsequent treatment failure. The purpose of this study was to: (1) assess the ability of serum D-dimer and other standard-of-care serum biomarkers to predict failure following reimplantation, and (2) establish a new cutoff value for serum D-dimer for prognostic use prior to reimplantation.

Aim

Whether laminar airflow (LAF) in the operating room (OR) is effective for decreasing periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) remains a clinically significant yet controversial issue. This study investigated the association between operating room ventilation systems and the risk of PJI in TJA patients.

Aim

Rifampin is considered as the antibiotic corner stone in the treatment of acute staphylococcal periprosthetic joint infections (PJI). However, if, when, and how to use rifampin has been questioned. We evaluated the outcome of patients treated with and without rifampin, and analysed the influence of timing, dose and co-antibiotic.

A growing number of recent investigations on the human genome, gut microbiome, and proteomics suggests that the loss of mucosal barrier function, particularly in the gastrointestinal tract, may substantially affect antigen trafficking, ultimately influencing the close bidirectional interaction between the gut microbiome and the immune system. This cross-talk is highly influential in shaping the host immune system and ultimately clinical infections. The hypothesis of the current study was that a change in microbiome and/or breach in GI epithelial barrier could be partially responsible for development of periprosthetic joint infections (PJI).

Multiple biomarkers of gut barrier disruption were tested in parallel in plasma samples collected as part of a prospective cohort study of patients undergoing revision arthroplasty for aseptic failures or PJI (As defined by the 2018 ICM criteria). All blood samples were collected before any antibiotic was administered. Samples were tested for Zonulin, soluble CD14 (sCD14), and lipopolysaccharide (LPS) using commercially available enzyme-linked immunosorbent assays. Statistical analysis consisted of descriptive statistics, Mann-Whitney t-test, and Kruskal-Wallis test.

A total of 134 patients were consented and included in the study. 44 were classified as PJI (30 chronic and 14 acute), and 90 as aseptic failures (26 primaries and 64 aseptic revisions). Both Zonulin and sCD14, but not LPS, were found to be significantly increased in the PJI group compared to non-infected cases (p<0.001; p=0.003). Higher levels of Zonulin were found in acute infections compared to chronic PJI (p=0.005

This prospective ongoing study reveals a possible link between gut permeability and the ‘gut-immune-joint axis’ in PJI. If this association continues to be born out with larger cohort recruitment and more in-depth analysis, it would have an immense implication in managing patients with PJI. In addition to administering antimicrobials, patients with PJI and other orthopedic infections may require gastrointestinal modulators such as pro and prebiotics.

Aims

The optimal management of an infrapopliteal deep venous thrombosis (IDVT) following total knee arthroplasty (TKA) remains unknown. The risk of DVT propagation and symptom progression must be balanced against potential haemorrhagic complications associated with administration of anticoagulation therapy. The current study reports on a cohort of patients diagnosed with IDVT following TKA who were treated with aspirin, followed closely for development of symptoms, and scanned with ultrasound to determine resolution of IDVT.

Introduction

Surgical management of PJI remains challenging with patients failing treatment despite the best efforts. An important question is whether these later failures reflect reinfection or the persistence of infection. Proponents of reinfection believe hosts are vulnerable to developing infection and new organisms emerge. The alternative hypothesis is that later failure is a result of an organism that was present in the joint but was not picked up by initial culture or was not a pathogen initially but became so under antibiotic pressure. This multicenter study explores the above dilemma. Utilizing next-generation sequencing (NGS), we hypothesize that failures after two stage exchange arthroplasty can be caused by an organism that was present at the time of initial surgery but not isolated by culture.

Aims

Failure of irrigation and debridement (I&D) for prosthetic joint infection (PJI) is influenced by numerous host, surgical, and pathogen-related factors. We aimed to develop and validate a practical, easy-to-use tool based on machine learning that may accurately predict outcome following I&D surgery taking into account the influence of numerous factors.

Aims

The aim of this study was to determine if a three-month course of microorganism-directed oral antibiotics reduces the rate of failure due to further infection following two-stage revision for chronic prosthetic joint infection (PJI) of the hip and knee.

Aim

Treatment success of debridement, antibiotics and implant retention (DAIR) is in early periprosthetic joint infection (PJI) is largely dependent on the presence or absence of a mature biofilm. In what time interval a mature biofilm develops is still unclear, and therefore, the time point at which DAIR should be disrecommended remains to be established. This large multicenter trial evaluated the failure rates of DAIR for different time intervals from index arthroplasty to DAIR in early PJI.

Background

The purpose of this multi-center, randomized clinical trial was to compare static and articulating spacers in the treatment of PJI complicating total knee arthroplasty TKA.

Introduction

Next generation sequencing (NGS) has been shown to facilitate detection of microbes in a clinical sample, particularly in the setting of culture-negative periprosthetic joint infection (PJI). However, it is unknown whether every microbial DNA signal detected by NGS is clinically relevant. This multi-institutional study was conceived to 1) identify species detected by NGS that may predict PJI, then 2) build a predictive model for PJI in a developmental cohort; and 3) validate the predictive utility of the model in a separate multi-institutional cohort.

Introduction

Femoroacetabular impingement(FAI) is a relatively common cause causes of hip pain and dysfunction in active young adults. The concept of FAI was popularized by Ganz et al in early 2000s. Surgical treatment for FAI has been widely employed over the last two decades. The long term outcome of femoroacetabular osteoplasty (FAO) and risk factors for long-term failure of FAO is less studied. The goal of this single surgeon series is to identify the long term outcome of FAO (minimum 10-year follow-up) and risk factors for surgical treatment failure in these patients.

Aims

The best marker for assessing glycaemic control prior to total knee arthroplasty (TKA) remains unknown. The purpose of this study was to assess the utility of fructosamine compared with glycated haemoglobin (HbA1c) in predicting early complications following TKA, and to determine the threshold above which the risk of complications increased markedly.

Introduction

Despite recent advances in the diagnosis of periprosthetic joint infection(PJI), identifying the infecting organism continues to be a challenge, with up to a third of PJIs reported to have negative cultures. Current molecular techniques have thus far been unable to replace culture as the gold standard for isolation of the infecting pathogen. Next- generation sequencing(NGS) is a well-established technique for comprehensively sequencing the entire pathogen DNA in a given sample and has recently gained much attention in many fields of medicine. Our aim was to evaluate the ability of NGS in identifying the causative organism(s) in patients with PJI.

Introduction

The use of irrigation solution during surgical procedures is a common and effective practice in reduction of bioburden and the risk of subsequent infection. The optimal irrigation solution to accomplish this feat remains unknown. Many surgeons commonly add topical antibiotics to irrigation solutions assuming this has topical effect and eliminates bacteria. The latter reasoning has never been proven. In fact a few prior studies suggest addition of antibiotics to irrigation solution confers no added benefit. Furthermore, this practice adds to cost, has the potential for anaphylactic reactions, and may also contribute to the emergence of antimicrobial resistance. We therefore sought to compare the antimicrobial efficacy and cytotoxicity of irrigation solution containing polymyxin-bacitracin versus other commonly used irrigation solutions.

Background

Recent reports demonstrate that Next Generation Sequencing (NGS) facilitates pathogen identification in the context of culture-negative PJI; however the clinical relevance of the polymicrobial genomic signal often generated remains unknown. This study was conceived to explore: (1) the ability of NGS to identify pathogens in culture-negative PJI; and (2) determine whether organisms detected by NGS, as part of a prospective observational study, had any role in later failure of patients undergoing surgical treatment for PJI.

Aim

Late acute prosthetic joint infections (PJI) treated with surgical debridement and implant retention (DAIR) have a high failure rate. The aim of our study was to evaluate treatment outcome in late acute PJIs treated with DAIR versus implant removal.

Aim

A two-stage exchange of an infected prosthetic joint (PJI) is considered the most effective surgical treatment of chronic PJIs, particularly in North America. However, reinfection rates are unacceptably high (10–20%). This could be the consequence of a persistent infection or a new infection introduced during the first or second stage of the exchange arthroplasty. We aimed to determine: i) the prevalence of positive cultures at reimplantation, ii) whether there is an association between positive cultures at reimplantation and reinfection during follow-up, and iii) if there is a microbiological correlation between primary infections, reimplantations and reinfections.

Aim

Debridement, antibiotics and implant retention (DAIR) is the recommended treatment for all acute prosthetic joint infections (PJI). However, the efficacy of DAIR and identification of risk factors for failure in patients with late acute PJI, is not well described.

Aims

The aim of this study was to examine the association between postoperative glycaemic variability and adverse outcomes following orthopaedic surgery.

Periprosthetic joint infection (PJI) is a devastating complication of total hip arthroplasty (THA). According to registry-based studies, some bearing couples are associated with an increased risk of PJI. The recent International Consensus on Periprosthetic Joint Infection stated that metal-on-metal (MOM) bearing surface appeared to be associated with a higher incidence of PJI. Based on emerging reports, the incidence of PJI appears to be different among different bearing surfaces. We conducted a multi-institutional study attempting to study this exact issue. The purpose of the study was to determine whether there was any difference in the incidence of PJI in two commonly used bearing couples (metal- on-polyethylene versus ceramic-on-polyethylene).

Based on a retrospective multi-institutional query all patients who received primary THA with MOP or COP bearing surfaces performed during 2005–2009 in two high-volume arthroplasty centers were identified. Demographic factors, comorbidities, length of hospital stay, complications and other relevant information were extracted. PJI was defined based on the MSIS (International Consensus) criteria. Multivariate analysis was performed to determine whether bearing coupling was independently correlated with PJI.

In our data, 25/2,921 (0.9%) patients with MOP and 11/2,643 (0.4%) patients with COP developed PJI. This difference was statistically significant (p=0.01). After the multivariate analysis, controlling for potential confounders (age, body mass index and length of hospital stay, Charlson comorbidity index), MOP bearing surface was found to be an independent factor correlating with higher incidence of PJI (odds ratio: 2.6, 95% confidence interval: 1.02–6.54, p=0.04).

The finding of this study, and others from centers in Europe, suggest that the bearing surface may have an influence on the incidence of PJI. Although, we had originally thought that ceramic bearing surfaces may be used in younger and healthier patients, the multivariate analyses that controlled for all these variables confirms that use of metal femoral head is an independent risk factor for development of PJI. The finding of this study is compelling and begs for future basic science mechanistic investigations.

Historical perspective: Irrigation and debridement (I&D) with modular exchange has historically been the recommended treatment for acute post-operative periprosthetic joint infection (PJI), and acute hematogenous PJI. The theory supporting this practice was that because the bacterial glycocalyx had not yet formed by these early time points, by simply debriding the intra-articular bacterial load and exchanging the modular parts, one could potentially eradicate the infection, retain the prior components, and minimise morbidity to the patient. More recently, literature is coming out suggesting that this may not necessarily be the case.

The vast majority of published research on the outcomes following I&D for treatment of PJI has focused on either cohorts of total knee arthroplasty patients or combined cohorts of total hip and knee patients. For this reason, it is difficult to tease out the differential success rate of periprosthetic hip vs. knee infections. Sherrell et al. performed a systematic review of the existing literature and created a table detailing the failure rates for various published articles on I&D for periprosthetic TKA infection.

Since it is the glycocalyx that has been thought to be the reason for treatment failure of many cases of PJI treated with I&D, many authors have implicated staphylococcal species as a predictor of a negative outcome with failure rates ranging from 30–35%. Methicillin resistant organisms have been shown to be particularly difficult to eradicate with an isolated I&D, with a 72–84% failure rate at 2 year follow-up. Interestingly, a recent study by Odum et al. suggests that neither the infecting microbe, nor the antibiotic resistance profile of the organism, as has been classically thought, actually predicts success of I&D.

Previous reports have indicated that the ability of I&D to control infection is related to the duration of symptoms and its timing relative to the index surgery. However, more recent literature is coming out to support the contrary. Koyonos et al. reviewed the outcomes of a series of 138 cases of PJI treated with I&D based on acuity of infection and concluded that an I&D has a limited role in controlling PJI regardless of acuity.

Intuitively, the physical health of the host/patient should influence the success of I&D for treatment of PJI. Several authors have shown that an immunocompromised state is a predictor of treatment failure. Furthermore, Azzam et al. reported that patients with a higher American Society of Anesthesia (ASA) score, a proxy of severity of medical comorbidities, had a significantly higher failure rate.

Although potentially appealing due to relative ease of execution and minimal surgical morbidity, the ability to successfully eradicate infection with an arthroscopic procedure may be compromised. Given the inability to perform a radical surgical debridement, nor exchange modular components, arthroscopic debridement should be used with extreme reservation in any case of PJI, regardless of the host, nature of the infecting organism, or acuity of infection.

I&D as a conservative, less morbid alternative to two-stage exchange - There is a growing body of literature to suggest that an I&D with modular component exchange may not be the benign, less morbid alternative to the ‘gold standard’ two-stage exchange arthroplasty. In fact, Fehring et al. has reported that the success of a two-stage antibiotic spacer exchange arthroplasty may be compromised by an initial I&D. They found that patients who were initially treated with an I&D only had a 66% chance of eradicating infection following a two-stage exchange arthroplasty, in contrast to historical reports of 80–90% success.

Aims

The diagnosis of periprosthetic joint infection can be difficult due to the high rate of culture-negative infections. The aim of this study was to assess the use of next-generation sequencing for detecting organisms in synovial fluid.

Next-generation sequencing (NGS) is a well-established technique for amplification and sequencing of DNA and has recently gained much attention in many fields of medicine. Our aim was to evaluate the ability of NGS in identifying the causative organism(s) in patients with periprosthetic joint infection (PJI).

In this prospective study samples were collected from 78 revision total hip arthroplasties. Synovial fluid, deep tissue and swabs were obtained at the time of surgery and shipped to the laboratory for NGS analysis. Deep tissue specimens were also sent to the institutional lab for culture. PJI was diagnosed using the Musculoskeletal infection society (MSIS) definition of PJI.

Thirty-four revisions were considered infected; culture was positive in 25 of these (25/34, 73.5%), while NGS was positive in 26 (26/34, 76.4%). Among the positive cultures, complete concordance between NGS and culture in 21 cases (21/25, 84.0%). 4 cases were discordant. Among these cases, 3 cases were culture-positive and NGS-negative, while 1 was both positive on NGS and culture for disparate organisms. Among the 9 cases of culture-negative PJI(CN-PJI), NGS was able to identify an organism in 4 cases (4/9, 44.4%). The remaining 5 cases were negative on both NGS and culture (5/9, 55.6%). Forty-four revisions were considered to be aseptic; NGS exclusively identified microbes in 7 of 44 “aseptic” revisions (15.9%) and culture exclusively isolated an organism in 3 of 44 cases (6.8%). Both NGS and culture were positive in 1 of case however the result was discordant. The remaining cases (33/44, 75.0%) were both NGS and culture negative. NGS detected several organisms in most positive samples, with a greater number of organisms detected in aseptic compared to septic cases (7 vs. 3.7, respectively).

NGS may be a promising technique for identifying the infecting organism in PJI. Our findings suggest that some cases of PJI may be polymicrobial that escape detection using conventional culture.

Aims

The aims of this study were to compare the efficacy of two agents, aspirin and warfarin, for the prevention of venous thromboembolism (VTE) after simultaneous bilateral total knee arthroplasty (SBTKA), and to elucidate the risk of VTE conferred by this procedure compared with unilateral TKA (UTKA).

Aim

Diagnosis of periprosthetic joint infection (PJI) presents a real challenge in some patients. Batteries of tests are available to reach this diagnosis. It is unknown if blood cultures have any role in diagnosis of PJI. The objective of this study was to evaluate whether blood cultures, taken in a group of patients with PJI, was useful in identifying the infecting pathogen.

The number of arthroplasties being performed increases each year. Patients undergoing an arthroplasty are at risk of venous thromboembolism (VTE) and appropriate prophylaxis has been recommended. However, the optimal protocol and the best agent to minimise VTE under these circumstances are not known. Although many agents may be used, there is a difference in their efficacy and the risk of bleeding. Thus, the selection of a particular agent relies on the balance between the desire to minimise VTE and the attempt to reduce the risk of bleeding, with its undesirable, and occasionally fatal, consequences.

Acetylsalicylic acid (aspirin) is an agent for VTE prophylaxis following arthroplasty. Many studies have shown its efficacy in minimising VTE under these circumstances. It is inexpensive and well-tolerated, and its use does not require routine blood tests. It is also a ‘milder’ agent and unlikely to result in haematoma formation, which may increase both the risk of infection and the need for further surgery. Aspirin is also unlikely to result in persistent wound drainage, which has been shown to be associated with the use of agents such as low-molecular-weight heparin (LMWH) and other more aggressive agents.

The main objective of this review was to summarise the current evidence relating to the efficacy of aspirin as a VTE prophylaxis following arthroplasty, and to address some of the common questions about its use.

There is convincing evidence that, taking all factors into account, aspirin is an effective, inexpensive, and safe form of VTE following arthroplasty in patients without a major risk factor for VTE, such as previous VTE.

Cite this article: Bone Joint J 2017;99-B:1420–30.

Revision of total hip arthroplasty (THA) is being performed with increasing frequency. However, outcomes of repeated revisions have been rarely reported in the literature, especially for severe defects. Cup revision can be a highly complex operation depending on the bone defect. In acetabular defects like Paprosky types 1 and 2 porous cementless cups maybe fixed with screws give good results. Modern trabecular metal designs improve these good results. Allografts are useful for filling cavitary defects. In acetabular defects Paprosky types 3A and 3B, impacted morselised allografts with a cemented cup technique produce good results. Difficult cases with pelvic discontinuity require reconstruction of the acetabulum with acetabular plates or large cup-cages to solve these difficult problems. However, there is still no consensus regarding the best option for reconstructing hips with bone loss. Although the introduction of ultraporous metals has significantly increased the surgeon's ability to reconstruct severely compromised hips, there remain some that cannot be managed readily using cups, augments, or cages. In such situations custom acetabular components may be required. Individual implants represent yet another tool for the reconstructive surgeon. These devices can be helpful in situations of catastrophic bone loss. Ensuring long-term outcome mechanical stability has a greater impact than restoring an ideal center of rotation.

We have done so far 15 3D Printed Individual Implants. All of them where Paprosky Type 3B defects, 10 with a additional pelvis discontinuity. The mean follow-up is 18 months. All implanted devices are still in place, no infection, no loosening.

However, despite our consecutive case series, there are no mid- to long-term results available so far. Re-revision for failed revision THA acetabular components is a technically very challenging condition.

The 3D Printed Individual Implants have a lot of advantages, like excellent surgical planning and a very simple technique (operative time, blood loss, instruments). They are a very stable construct for extensive acetabular defects and pelvic discontinuity.

The burden of periprosthetic joint infection (PJI) continues to rise and the management of this dreaded complication continues to pose challenges to the orthopaedic community. Dr Buchholz from the Endo Klinik has been credited for reporting the initial observation that addition of antibiotic to polymethylmethacrylate (PMMA) cement lead to better ability to deliver higher concentrations of antibiotic to the joint milieu and avoid administration of high doses of systemic antibiotics with potential for systemic toxicity.

Addition of antibiotics to PMMA cement has continued to be an important aspect of managing patients with chronic PJI. The rationale for this practice is that higher doses of local antibiotics can be reached without placing the patients at risk of systemic toxicity. Whether a one-stage or a two-stage exchange arthroplasty is being performed, antibiotics that can withstand the exothermic reaction of PMMA and are able to elude from cement are added at various doses to the PMMA for later delivery. Although this practice continues to be almost universal, there are a few unknowns. First of all, a recent study raised a valid question regarding this practice. Though intuitively logical, addition of antibiotics to PMMA spacers has not been scrutinised by any level 1 study and hence one is not able to prove that this practice does indeed accomplish its intended objectives of reducing recurrence or persistence of infection. Orthopaedic community is advised to seek avenues to generate this much-needed evidence. The other main unknown is how much, and in some instances which antibiotic, needs to be added to the PMMA cement. Some authorities have declared that antibiotics can be added at high doses, with an average total dose of 10.5 g of vancomycin (range, 3–16 g) and 12.5 g of gentamicin (range, 3.6–19.2 g) in one study, to PMMA cement without the fear of systemic toxicity.

In recent years, renal toxicity and other systemic adverse effects have been attributed to addition of high doses of antibiotics to cement. I have personally witnessed such adverse reactions in a few patients. Although initially I was inclined to “blame” the concurrent administration of systemic antibiotics for the renal toxicity that patients developed following insertion of spacer, selective nephrotoxicity (i.e. reaction to aminoglycoside that was only present in the spacer and not systemically administered) and resolution of the nephrotoxicity upon removal of antibiotic spacer, convinced me that our nephrology colleagues have a valid reason to be concerned about addition of high doses of antibiotics to PMMA spacers.

What has become clear is that high viscosity cements containing MA-MMA copolymers have been shown to have better antibiotic elution profiles than other PMMA formulations. So when fashioning a spacer in the operating room the surgeon needs to be aware of the differences in elution profile of antibiotics from PMMA and individualise the dose of antibiotics being added to spacer based on the type and viscosity of cement being used and the renal status of the patient. Thus, systemic toxicity caused by addition of antibiotics to cement spacer appears to be a real issue in some circumstances and this needs to be born in mind when managing patients with PJI.

There are numerous other issues related to the use of antibiotic cement spacers. In the hip, the lack of adequate offset and limited portfolio of products result in laxity in the soft tissue and subsequent dislocation of the hip. In addition, the dose and type of antibiotic in the premanufactured spacers, at least in the US, are inadequate to lead to a substantial delivery of antibiotics in the local tissues. Because of these issues, I prefer to fabricate “customised” spacers for each patient that I operate on.

Femoral revision in cemented THA might include some technical difficulties, based on loss of bone stock and cement removal, which might lead to further loss of bone stock, inadequate fixation, cortical perforation or consequent fractures. Femoral impaction grafting, in combination with a primary cemented stem, allows for femoral bone restoration due to incorporation and remodelling of the allograft bone by the host skeleton. Historically it has been first performed and described in Exeter in 1987, utilizing a cemented tapered polished stem in combination with morselised fresh frozen bone grafts. The technique was refined by the development of designated instruments, which have been implemented by the Nijmegen group from Holland. Indications might include all femoral revisions with bone stock loss, while the Endo-Clinic experience is mainly based on revision of cemented stems. Cavitary bone defects affecting meta- and diaphysis leading to a wide or so called “drain pipe” femora, are optimal indications for this technique, especially in young patients. Contraindications are mainly: septical revisions, extensive circumferential cortical bone loss and noncompliance of the patient.

Generally, the technique creates a new endosteal surface to host the cemented stem by reconstruction of the cavitary defects with impacted morselised bone graft. This achieves primary stability and restoration of the bone stock. It has been shown, that fresh frozen allograft shows superior mechanical stability than freeze-dried allografts. Incorporation of these grafts has been described in 89%. Technical steps include: removal of failed stem and all cement, reconstruction of segmental bone defects with metal mesh (if necessary), preparation of fresh frozen femoral head allografts with bone mill, optimal bone chip diameter 2–5 mm, larger chips for the calcar area (6–8 mm), insertion of an intramedullary plug including central wire, 2 cm distal the stem tip, introduction of bone chips from proximal to distal, impaction started by distal impactors over central wire, then progressive larger impactors proximal, insertion of a stem “dummy” as proximal impactor and space filler, removal of central wire, retrograde insertion of low viscosity cement (0.5 Gentamycin) with small nozzle syringe, including pressurization, and insertion of standard cemented stem. The cement mantle is of importance, as it acts as the distributor of force between the stem and bone graft and seals the stem. A cement mantle of at least 2 mm has shown favorable results. Post-operative care includes usually touch down weightbearing for 6–8 weeks, followed by 4–6 weeks of gradually increased weightbearing with a total of 12 weeks on crutches.

Relevant complications include mainly femoral fractures due to the hardly impacted allograft bone. Subsidence of tapered polished implants might be related to cold flow within the cement mantle, however, could also be related to micro cement mantle fractures, leading to early failure. Subsidence should be less than 5 mm. Survivorship with a defined endpoint as any femoral revision after 10-year follow up has been reported by the Exeter group being over 90%, while survivorship for revision as aseptic loosening being above 98%. Within the last years various other authors and institutions reported about similar excellent survivorships, above 90%. In addition, a long-term follow up by the Swedish arthroplasty registry in more than 1180 patients reported a cumulative survival rate of 94% after 15 years.

Impaction grafting might technically be more challenging and more time consuming than cement-free distal fixation techniques. It, however, enables a reliable restoration of bone stock which might especially become important in further revision scenarios in younger patients.

Venous thromboembolism (VTE) prophylaxis following total joint arthroplasty (TJA) should be individualised in order to maximise the efficacy of prophylactic measures while avoiding the adverse events associated with the use of anticoagulants. At our institution, we have developed a scoring model using the Nationwide Inpatient Sample (NIS) database, which is validated against our institutional data, to stratify patients into low- and high-risk groups for VTE. Low-risk patients are placed on aspirin 81 mg twice daily for four weeks post-operatively, and high-risk patients are placed on either a Vitamin K antagonist (warfarin), low molecular weight heparin, or other oral anticoagulants for four weeks post-operatively. All patients receive sequential pneumatic compression devices post-operatively, and patients are mobilised with physical therapy on the day of surgery. Patients who have a history of peptic ulcer disease or allergy to aspirin are also considered for other types of anticoagulation following surgery.

Risk Stratification Criteria

Major comorbid risk factors utilised in our risk stratification model include history of hypercoagulability or previous VTE, active cancer or history of non-cutaneous malignancy, history of stroke, and pulmonary hypertension. We consider patients with any of these risk factors at elevated risk of VTE and therefore candidates for formal anticoagulation.

Other minor risk factors include older age, bilateral surgery compared with unilateral, inflammatory bowel disease, varicose veins, obstructive sleep apnea, and history of myocardial infarction, myeloproliferative disorders, and congestive heart failure. Each minor criterion is associated with a score. The cumulative score is compared with a defined threshold and the score that surpasses the threshold indicates that the patient should receive post-operative anticoagulation. To facilitate the use of this scoring system, an iOS mobile application (VTEstimator) has been developed and can be downloaded from the app store.

The World Health Organization (WHO) and the Centre for Disease Control and Prevention (CDC) recently published guidelines for the prevention of surgical site infection. The WHO guidelines, if implemented worldwide, could have an immense impact on our practices and those of the CDC have implications for healthcare policy in the United States.

Our aim was to review the strategies for prevention of periprosthetic joint infection in light of these and other recent guidelines.

Cite this article: Bone Joint J 2017;99-B(4 Supple B):3–10.

Background

There are several surgical options available for patients with bilateral knee osteoarthritis including simultaneous bilateral TKA (BTKA) and staged approach. The appropriate and safe time interval between two stages is still controversial. The preset systematic review aims to determine the optimal time interval between two stages of BTKA.

Introduction

Reported data on impact of obesity on outcome of total joint arthroplasty (TJA) is mixed. The purpose of this systematic review was to evaluate the impact of obesity on surgical procedure and postoperative outcomes after total hip and knee arthroplasty.

There are a number of progressive conditions that afflict the hip and result in degenerative arthritis. Along the path of progression of the disease and prior to the development of arthritis, some of these conditions may be treatable by joint preservation procedures. Periacetabular osteotomy for developmental dysplasia of the hip (DDH), femoroacetabular osteoplasty for femoroacetabular impingement (FAI), and a variety of surgical procedures for management of early osteonecrosis of the femoral head are some examples of joint preservation of the hip. DDH is characterised by abnormal development of the acetabulum and the proximal femur that leads to suboptimal contact of the articular surfaces and the resultant increase in joint reaction forces. FAI is a condition characterised by an abnormal contact between the femoral neck and the acetabular rim. FAI is believed to exist when a triad of signs (abnormal alpha angle, labral tear, and chondral lesion) can be identified.

The question that remains is whether joint preservation procedures are able to avert the need for arthroplasty or just an intervention along the natural path of progression of the hip disease. There is an interesting study that followed 628 infants born in a Navajo reservation, including 8 infants with severe dysplasia, for 35 years. None of the children with DDH had surgical treatment and all had developed severe arthritis in the interim. The latter study and a few other natural history studies have shown that the lack of administration of surgical treatment to patients with symptomatic DDH results in accelerated arthritis. The situation is not so clear with FAI. Some believe that FAI is a pre-arthritic condition and surgical treatment is only effective in addressing the symptoms and does not delay or defer an arthroplasty. While others believe that restoration of the normal mechanical environment to the hip of FAI patients, by removing the abnormal contact and repair of the labrum, is likely to change the natural history of the disease and at minimum delay the need for an arthroplasty. There is a need for natural history studies or case series to settle the latter controversy.

Total hip arthroplasty continues to be one of the most effective procedures. Aseptic loosening compromises the long term outcome of this otherwise successful procedure. Large hemispherical cups may be used during revision surgery for patients with severe bone loss. Acetabular revision with cementless components has been remarkably successful with some series reporting no revisions for aseptic loosening at an average follow-up of 13.9 years. Another study on 186 patients (196 hips) receiving jumbo acetabular components, noted a survivorship of 98% at 4 years and 96% at 16 years. Cementless acetabular revision is now feasible for a wide range of revision situations, including some cases of pelvic discontinuity. The Paprosky classification is useful in predicting the reconstructive technique that will be required. Type I and many Type II defects may be reconstructed with standard cementless components. Many Type II and Type III defects, which involve the loss of additional structural bone, can be reconstructed with a jumbo cup. A jumbo cup is defined by Whaley et al. as a component that is >61 mm in women and >65 mm in men, a definition that is based on a shell that is >10 mm greater than the average diameter cup implanted in women and men. The jumbo cup has the advantage of an increased contact area between host bone and cup which maximises the surface area for ingrowth or ongrowth. The increased area of contact also prevents cup migration by allowing for force dissipation over a large area. Use of a jumbo cup may also decrease the need to use bone graft. In contrast to positioning the cup in the so-called high hip center, a jumbo cup can help to restore the hip center of rotation.

The disadvantages of this technique are that host bone may have to be removed to implant the cup, that bone stock is not restored by the reconstruction, and that hemispherical cups have limited applicability in situations of oblong bone stock deficiency.

Jumbo acetabular components can be used in combination with both structural and cancellous bone graft. In these cases, the cementless cup must achieve adequate contact with host bone in order to allow bone ingrowth to occur.

Aim

Different perioperative strategies have been implemented to reduce the devastating burden of infection following arthroplasty. The use of iodophor-impregnated adhesive incise drapes is one such strategy. Despite its wide adoption, there is little proof that this practice leads to a reduction of bacterial colonization. The aim of this randomized, prospective study was to evaluate the efficacy of iodophor-impregnated adhesive drapes for reducing bacterial count at the incision site.

There is no doubt that peri-prosthetic joint infection (PJI) is one the most terrible complications of joint arthroplasty. There has been a surge of interest in PJI in recent years as this problem moves to be the last frontier in joint arthroplasty.

There are a number of strategies employed for prevention of PJI. Irrigation of the surgical site with various irrigation solutions is one such strategy as it helps reduce bioburden in the wound and reduce the potential for subsequent infection.

Although the irrigation solution may work by dilution phenomenon alone, some believe that bactericidal or bacteriostatic agents may be added to the irrigation solution to increase its efficacy. Addition of antibiotics (Abx) to the irrigation solution stems from the same reasoning.

There are a number of serious issues related to the addition of Abx to the irrigation solution or in fact, for pouring into the wound (like the vancomycin powder).

Efficacy: There are no randomised prospective studies to demonstrate that addition of Abx to the irrigation solution improves “kill”. To do such a study would be logistically challenging. Basic science studies and other clinical studies with a small number of patients have failed to prove the efficacy of Abx in the irrigation solution. In fact, I would argue that the use of agents like dilute betadine is much more likely to be effective in reduction of bioburden without having many of the issues related to the use of Abx in irrigation solution.

Emergence of Resistance: Some may argue what would one lose by adding Abx to the wound or the irrigation solution. The modern society is facing an emerging catastrophe. Antimicrobial Resistance (AMR), if it persists, will kill more people than cancer by the year 2050. Annually 1000s of patients die of ESKAPE or AMR related issues. A recent task force convened by the British government produced a report about AMR which is sobering. The main finding of the task force was that continued liberal use of Abx will lead to further escalation of the AMR crisis that threatens the modern society. The guidelines by the CDC, that are about to be published, will discourage clinicians from pouring Abx into wounds and asks clinicians to exercise Abx stewardship.

Expense: There are costs associated with the use of Abx in any circumstance including their addition to irrigation solution. With over 1 million joint arthroplasties being done in the US alone, this cost can be substantial.

Hypersensitivity reactions: The use of Abx is not without problems. There have been a few fatalities associated with the use of Abx in patients with recognised and possibly unrecognised hypersensitivity to antibiotics.

Peri-prosthetic joint infection (PJI) is one the most devastating complications of joint arthroplasty. Although PJI is an infrequent complication (the reported incidence is 1%-2% in the United States), it is the most common indication for revision total knee arthroplasty in the Medicare population and the third most frequent indication for revision total hip arthroplasty. Moreover, the prevalence of PJI appears to be on the rise, with a projected number exceeding 60,000 to 70,000 cases in the United States by 2020.

It is estimated that more than 25% of revision procedures annually are attributed to PJI and this number is expected to increase in the upcoming years. The increase in the prevalence of obesity, diabetes, and other comorbidities among the patient population and the emergence of resistant infecting organisms are some of the reasons for the expected rise in the number of infections that medical community will witness.

The challenges that PJI present to the orthopaedic community are on many fronts. Prevention of PJI has proven to be a difficult task indeed. Effective strategies for prevention of PJI are being refined. The Center for Disease Control will be publishing its updated Surgical Site Prevention Guidelines in the next few months that consists of specific recommendations for prevention of PJI. In recent years, strides are made in introducing novel molecular techniques for diagnosis of PJI, which may stand to change our practices. The current surgical technique for management of PJI, besides the immense cost, fall short of delivering high success to the patients. The major problem in eradication of infection relates to formation of biofilm on the implant surface and internalization of the organisms by affected cells. Biofilm is a sophisticated structure comprising of organisms embedded in multiple layers of glycoccalyx that allows the organisms to evade host immunity and is impenetrable to antibiotics. These organisms are capable of communicating through molecular mechanisms such as quorum sensing that affords them advantage for survival in the host environment. In recent years strategies to prevent colonization of the implant surface, an essential first step in formation of biofilm, or biofilm disruption techniques have been introduced. A recent International Consensus meeting on PJI that assembled more than 350 experts identified some of the best practices in this field and identified areas in need of future research. Moving into the future, the field of orthopaedics in general and PJI in particular stand to benefit from the discoveries in the field of molecular diagnostics, metabolomics and epigenetics.

Aims

We aimed to assess the influence of ethnicity on the incidence of heterotopic ossification (HO) after total hip arthroplasty (THA).

Computer-aided surgical systems commonly use preoperative CT scans when performing pelvic osteotomies for intraoperative navigation. These systems have the potential to improve the safety and accuracy of pelvic osteotomies, however, exposing the patient to radiation is a significant drawback. In order to reduce radiation exposure, we propose a new smooth extrapolation method leveraging a partial pelvis CT and a statistical shape model (SSM) of the full pelvis in order to estimate a patient's complete pelvis. A SSM of normal, complete, female pelvis anatomy was created and evaluated from 42 subjects. A leave-one-out test was performed to characterise the inherent generalisation capability of the SSM. An additional leave-one-out test was conducted to measure performance of the smooth extrapolation method and an existing “cut-and-paste” extrapolation method. Unknown anatomy was simulated by keeping the axial slices of the patient's acetabulum intact and varying the amount of the superior iliac crest retained; from 0% to 15% of the total pelvis extent. The smooth technique showed an average improvement over the cut-and-paste method of 1.31 mm and 3.61 mm, in RMS and maximum surface error, respectively. With 5% of the iliac crest retained, the smoothly estimated surface had an RMS surface error of 2.21 mm, an improvement of 1.25 mm when retaining none of the iliac crest. This anatomical estimation method creates the possibility of a patient and surgeon benefiting from the use of a CAS system and simultaneously reducing the patient's radiation exposure.

Introduction

First-generation annealed HXLPE has been clinically successful at reducing both clinical wear rates and the incidence of osteolysis in total hip arthroplasty. However, studies have observed oxidative and mechanical degradation occurring in annealed HXLPE. Thus, it is unclear whether the favorable clinical performance of 1st generation HXLPE is due to the preservation of bearing surface tribological properties or, at least partially, to the reduction in patient activity. The purpose of this study was to evaluate the in vitro wear performance (assessed using multidirectional pin-on-disk (POD) testing) of 1^st-generation annealed HXLPE with respect to in vivo duration, clinical wear rates, oxidation, and mechanical properties.