Prosthetic Joint Infection Trends at a Dedicated Orthopaedics Specialty Hospital

Research and Application of Chitosan Nanoparticles in Orthopedic Infections

Orthopedic infection is one of the most intractable orthopedic problems. Bacteria resistant to antibiotics also develop gradually. Chitosan is widely used in the Biomedical field because of its high biocompatibility, biodegradability, and antibacterial activity. Chitosan-based drug delivery systems are frequently utilized to produce controlled medication release. When combined with antibiotics, synergistic antibacterial effects can be achieved. Chitosan-based nanoparticles are one of the most widely used applications in drug delivery systems. The focus of this review is to provide information on new methods being developed for chitosan-based nanoparticles in the field of bone infection treatment, including chitosan nanoparticles for antibacterial purposes, Ch-loaded with antibiotics, Ch-loaded with metal, and used as immune adjuvants. It may Provide ideas for the fundamental research and the prospects of future clinical applications of orthopedic infections.

Reimbursement of Lumbar Fusion at an Orthopaedic Specialty Hospital Versus Tertiary Referral Center

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

To explore the differences in Medicare reimbursement for lumbar fusion performed at an orthopaedic specialty hospital (OSH) and a tertiary referral center and to elucidate drivers of Medicare reimbursement differences.

SUMMARY OF BACKGROUND DATA

To provide more cost-efficient care, appropriately selected patients are increasingly being transitioned to OSHs for lumbar fusion procedures. There are no studies directly comparing reimbursement of lumbar fusion between tertiary referral centers (TRC) and OSHs.

METHODS

Reimbursement data for a tertiary referral center and an orthopaedic specialty hospital were compiled through the Centers for Medicare and Medicaid Services. Any patient with lumbar fusions between January 2014 and December 2018 were identified. OSH patients were matched to TRC patients by demographic and surgical variables. Outcomes analyzed were reimbursement data, procedure data, 90-day complications and readmissions, operating room times, and length of stay (LOS).

RESULTS

A total of 114 patients were included in the final cohort. The tertiary referral center had higher post-trigger ($13,554 vs. $8,541, P <0.001) and total episode ($49,973 vs. $43,512, P <0.010) reimbursements. Lumbar fusion performed at an OSH was predictive of shorter OR time (β=0.77, P <0.001), shorter procedure time (β=0.71, P <0.001), and shorter LOS (β=0.53, P <0.001). There were no significant differences in complications (9.21% vs. 15.8%, P =0.353) or readmission rates (3.95% vs. 7.89%, P =0.374) between the 2 hospitals; however, our study is underpowered for complications and readmissions.

CONCLUSION

Lumbar fusion performed at an OSH, compared with a tertiary referral center, is associated with significant Medicare cost savings, shorter perioperative times, decreased LOS, and decreased utilization of post-acute resources.

LEVEL OF EVIDENCE

3.

Current Concepts on the Clinical and Economic Impact of Periprosthetic Joint Infections

Total joint arthroplasty (TJA) is a common procedure performed throughout the entire world in hopes of alleviating debilitating hip or knee pain. The projected number of TJAs performed in the United States alone is projected to exceed 1.9 million by 2030 and 5 million by 2040. With the significant increase in TJA performed, more periprosthetic joint infections (PJIs) are likely to be encountered. PJIs are a devastating complication of TJA. The economic and clinical burden must be understood and respected to minimize occurrence and allow optimal patient outcomes.

Intermittent alternating magnetic fields diminish metal-associated biofilm in vivo

Prosthetic joint infection (PJI) is a complication of arthroplasty that results in significant morbidity. The presence of biofilm makes treatment difficult, and removal of the prosthesis is frequently required. We have developed a non-invasive approach for biofilm eradication from metal implants using intermittent alternating magnetic fields (iAMF) to generate targeted heating at the implant surface. The goal of this study was to determine whether iAMF demonstrated efficacy in an in vivo implant biofilm infection model. iAMF combined with antibiotics led to enhanced reduction of biofilm on metallic implants in vivo compared to antibiotics or untreated control. iAMF-antibiotic combinations resulted in a > 1 - log further reduction in biofilm burden compared to antibiotics or iAMF alone. This combination effect was seen in both S. aureus and P. aeruginosa and seen with multiple antibiotics used to treat infections with these pathogens. In addition, efficacy was temperature dependent with increasing temperatures resulting in a greater reduction of biofilm. Tissue damage was limited (< 1 mm from implant-tissue interface). This non-invasive approach to eradicating biofilm could serve as a new paradigm in treating PJI.

Patient "No-Show" Increases the Risk of 90-Day Complications Following Primary Total Knee Arthroplasty: A Retrospective Cohort Study of 6,776 Patients

BACKGROUND

Patients who "no-show" (NS) clinical appointments are at a high risk of adverse health outcomes. The objective of this study was to evaluate and characterize the relationship between NS visits prior to primary total knee arthroplasty (TKA) and 90-day complications after TKA.

METHODS

We retrospectively reviewed 6,776 consecutive patients undergoing primary TKA. Study groups were separated based on whether patients who NS versus always attended their appointment. A NS was defined as an intended appointment that was not canceled or rescheduled ≤2 hours before the appointment in which the patient did not show. Data collected included total number of follow-up appointments prior to surgery, patient demographics, comorbidities, and 90-day postoperative complications.

RESULTS

Patients who have ≥3 NS appointments had 1.5 times increased odds of a surgical site infection (odds ratio (OR) 1.54, P = .002) compared to always attended patients. Patients who were ≤65 years old (OR: 1.41, P < .001), smokers (OR: 2.01, P < .001), and had a Charlson comorbidity index ≥3 (OR: 4.48, P < .001) were more likely to miss clinical appointments.

CONCLUSION

Patients who have ≥3 NS appointments prior to TKA had an increased risk for surgical site infection. Sociodemographic factors were associated with higher odds of missing a scheduled clinical appointment. These data suggest that orthopaedic surgeons should consider NS data as an important clinical decision-making tool to assess risk for postoperative complications to minimize complications following TKA.

Metagenomic Next-Generation Sequencing for Periprosthetic Joint Infections

Periprosthetic joint infection (PJI) after arthroplasty is a major complication, which requires significant resources, resulting in high costs for the medical system. In recent years, significant progress has been made in the diagnosis and treatment of periprosthetic infections, the identification of the pathogen being the central element in the establishment of targeted antibiotic therapy. Next-generation sequencing (NGS) or metagenomic NGS (mNGS) represents a promising, fast alternative, with increased specificity and sensitivity compared to identification methods using conventional culture media, thus enabling an increased rate of identification of pathogenic microorganisms and antibiotic resistance genes (ARG). The purpose of this article was to highlight new molecular diagnostic methods for periprosthetic joint infections and their involvement in treatment efficiency. NGS technologies are cutting-edge techniques that may challenge the PJI diagnostic model.

Emerging Technologies in Diagnosing Periprosthetic Joint Infections

Periprosthetic joint infection (PJI) is a well-known serious complication following joint replacement surgeries and is responsible for high failure rates of implanted devices. Any delay in the diagnosis can compromise treatment success, putting a huge burden on the patients' wellness and healthcare systems. Diagnosing PJIs is quite complex as there is still no gold standard test to reach the definitive diagnosis in a timely manner. A number of laboratory tests and radiological imaging inventions have evolved in the past few years, requiring consistent updates of the available guidelines to keep up with the latest advances in the field. This article highlights the recent advances in diagnosing PJIs and discusses their validity for use in clinical practice.

Articulating spacers: what are available and how to utilize them?

Periprosthetic joint infection (PJI) is the most devastating complication following total joint arthroplasty (TJA) and is posing a global healthcare challenge as the demand for TJA mounts. Two-stage exchange arthroplasty with the placement of antibiotic-loaded spacers has been shown to be efficacious against chronic PJI. This study aimed to review the key concepts, types, and outcome evaluations of articulating spacers in the two-stage exchange for PJI. Previous studies indicated that articulating spacers have been widely used due to better functional improvement and a comparable infection control rate relative to static spacers. Several types of articulating spacers are reportedly available, including hand-made spacers, spacers fashioned from molds, commercially preformed spacers, spacers with additional metal or polyethylene elements, new or autoclaved prosthesis, custom-made articulating spacers, and 3D printing-assisted spacers. However, limited evidence suggested no significant difference in clinical outcomes among the different subtypes of articulating spacers. Surgeons should be familiar with different treatment strategies when using various spacers to know which is the most appropriate.

Cartilage-inspired surface textures for improved tribological performance of orthopedic implants

Joint replacements have become one of the most common orthopedic procedures due to the significant demands of retaining functional mobility. While these procedures are of great value to patients, there are some limitations. Durability is the most important limitation associated with joint replacement that needs to be addressed due to the increasing number of younger patients. Titanium is a commonly used implant material which has high biocompatibility, high strength-to-density ratio, and high corrosion resistance. However, current titanium implants have poor wear resistance which shortens their lifespan. In this study, microscale dimples with four different dimple shapes (circular, triangular, square, and star) of similar sizes to the pores found in natural articular cartilage were fabricated on titanium disks to improve implant lubrication and reduce wear. Biotribology tests were performed on dimpled and non-dimpled titanium disks in a condition similar to that inside of a patient's body. It was shown that dimpling the titanium disks optimized the lubricant film formation and decreased the wear rate significantly while also reducing the coefficient of friction (COF). The star-shaped dimples had the lowest COF and almost no detectable wear after 8 h of testing. To investigate whether dimpling increased bacterial colonization due to increased surface area, and to determine whether any increase could be limited by coating with antibacterial materials, bacterial colonization with Staphylococcus aureus was tested with non-dimpled and star-shaped dimpled titanium disks with and without coating with polydopamine (PDA), silver (Ag) nanoparticles (NPs), and PDA + Ag NPs. It was found that dimpling did not increase bacterial colonization, and that coating with PDA, Ag NPs, or PDA + Ag NPs did not decrease bacterial colonization. Nevertheless, we conclude that star-shaped dimpled titanium surfaces have potential utility as more durable orthopedic implants.

"Recommendations for periprosthetic joint infections (PJI) prevention: the European Knee Associates (EKA)-International Committee American Association of Hip and Knee Surgeons (AAHKS)-Arthroplasty Society in Asia (ASIA) survey of members"

PURPOSE

Periprosthetic joint infections (PJIs) represent a devastating consequence of total joint arthroplasty. The European Knee Associates (EKA), the American Association of Hip and Knee Surgeons (AAHKS) International Committee, and the Arthroplasty Society in Asia (ASIA) board members were interested in quantifying differences in arthroplasty surgeons' use of various PJI prevention measures to provide clinical recommendations to reduce PJI incidence.

METHODS

A prospective Microsoft Forms online survey was distributed among EKA, AAHKS International Committee, and ASIA members and their affiliated arthroplasty surgeons. The survey consisted of 20 single and multiple response questions focused on PJI prevention strategies at three perioperative periods: preoperatively, intraoperatively, and postoperatively.

RESULTS

Three hundred and ninety-four arthroplasty surgeons from 6 different continents completed the survey. Preoperative: (A) PJI Risk Stratification: 40.6% routinely set thresholds (e.g., BMI, HgbA1C) to be met to qualify for surgery, 36.5% only review past medical history; 9.1% use machine learning to personalize PJI risk; (B) BMI limit: 36% no limit; 15.4% BMI < 35; 30.9% BMI < 40; 17.2% BMI < 45; (C) Nutritional status: 55.3% do not screen; among those who screen their patients (44.7%), albumin is the single most used marker (86.3%); (D) Hyperglycemia/Diabetes: 83.3% check this comorbidity; 88.1% use HgbA1C as single best screening test; (E) MRSA nasal colonization: 63.7% do not test; 28.9% test all patients; 7.4% test selectively. Intraoperative: (A) Antibiotic prophylaxis in high-risk patients: 43.4% use single antibiotic for 24 h; 21.3% use double antibiotic for 24 h; 14.2% use single/double antibiotic for 7 days postoperatively; (B) Skin-cleansing: 68.7% at home (45.6% chlorhexidine sponge; 11.9% clippers); (C) Intraoperative skin disinfection: 46.9% single chlorhexidine; 25% double chlorhexidine-povidone-iodine;15.4% single povidone-iodine; (D) Tranexamic acid (TXA) to reduce bleeding/SSI: 96% yes (51% double IV dose, 35.2% single IV dose, 23.6% intra-articular injection); (E) Surgical suction drain: 52% do not use drains; 19.7% use a drain < 24 h; (F) Intra-articular lavage: 64.9% use only saline; 28.1% use dilute povidone-iodine; (G) Antibiotic local delivery to prevent PJI: 82.4% use antibiotic-added cement. Postoperative: (A) Routine monitoring of PJI serologic markers: 42% only in symptomatic patients; 34.2% do not; 20.8% in all patients; (B) Serologic markers to rule in/out PJI: 95.9% CRP; 71% SEDRATE; 60.6% WBC; (C) Synovial fluid test to rule in/out PJI: 79.6% culture/sensitivity; 69.5% WBC count; 31.4% CRP.

CONCLUSIONS

This survey demonstrated that notable differences still exist in the application of PJI preventive measures across different geographic areas: Optimizing the patient preoperatively and applying multimodal intraoperative strategies represent newer, clinically relevant steps in the effort to reduce the burden of PJI. More uniform guidelines still need to be produced from international scientific societies in order facilitate a more comprehensive approach to this devastating complication.

LEVEL OF EVIDENCE

IV.

Cumulative Intraarticular Injections Are Not a Risk Factor for Periprosthetic Joint Infection Following total Knee Arthroplasty

BACKGROUND

While injections within 90 days prior to total knee arthroplasty (TKA) are associated with an increased risk of periprosthetic joint infection (PJI), there is a paucity of literature regarding the impact of cumulative injections on PJI risk. This study was conducted to assess the association between cumulative corticosteroid and hyaluronic acid (HA) injections and PJI risk following TKA.

METHODS

This retrospective study using an injection database included patients undergoing TKA with a minimum 1-year follow-up from 2015 to 2020. Patients with injections within 90 days prior to surgery were excluded. The sum of corticosteroid and HA injections within five years prior to TKA was recorded. The primary outcome was PJI within 90 days following TKA. Area under the curve (AUC) values were calculated for a cumulative number of injections.

RESULTS

648 knees with no injections and 672 knees with injections prior to TKA were included, among whom 243 received corticosteroids, 151 received HA, and 278 received both. No significant differences in early PJI rates existed between patients who received injections (0.60%) or not (0.93%) (P = .541). No significant differences existed in early PJI rates between patients injected with corticosteroids (0.82%), HA (0.66%), or both (0.36%) (P = .832). No cutoff number of injections was predictive for PJI.

DISCUSSION

A cumulative amount of steroid or HA injections, if given more than 90 days prior to TKA, does not appear to increase the risk of PJI within 90 days postoperatively. Multiple intraarticular corticosteroid injections and HA injections may be safely administered before TKA, without increased risk for early PJI.

Antibiotics- and Heavy Metals-Based Titanium Alloy Surface Modifications for Local Prosthetic Joint Infections

Prosthetic joint infection (PJI) is the second most common cause of arthroplasty failure. Though infrequent, it is one of the most devastating complications since it is associated with great personal cost for the patient and a high economic burden for health systems. Due to the high number of patients that will eventually receive a prosthesis, PJI incidence is increasing exponentially. As these infections are provoked by microorganisms, mainly bacteria, and as such can develop a biofilm, which is in turn resistant to both antibiotics and the immune system, prevention is the ideal approach. However, conventional preventative strategies seem to have reached their limit. Novel prevention strategies fall within two broad categories: (1) antibiotic- and (2) heavy metal-based surface modifications of titanium alloy prostheses. This review examines research on the most relevant titanium alloy surface modifications that use antibiotics to locally prevent primary PJI.

Functional and Cost Audit of Primary Total Knee Arthroplasty in Public vs Private Hospitals: A Retrospective Cohort Study

BACKGROUND

Government funded hospitals are believed to be stigmatised with 'substandard care' and constant fear of infection. The aim of this study is to compare the results and direct expenditure incurred for total knee arthroplasty (TKA) done at a government funded public teaching hospital with an economy packaged private hospital in India.

MATERIALS AND METHODS

A review of electronic and physical records of the patients operated by the senior author for primary TKA at a government funded hospital and a private hospital spanning 2007 to 2019 was done. A retrospective cohort study was designed matching the implant design and the ASA grade of the patients. Knee injury and Osteoarthritis Outcome Score (KOOS), Hospital for Special Surgery score (HSS), Knee Society Score (KSS) at 2 years follow-up were the primary outcome parameters. The retrieved data describing the cost of surgery and perioperative complications were analyzed. The confounders were minimized by including only the surgeries performed by the author, using the same instruments and implants in similar operating theatre environments.

RESULTS

This study involved two cohorts comprising 280 patients each, with no differences in gender, ASA grade and primary diagnosis. There was no significant difference in the 2-year HSS, KSS and KOOS score between the two groups. The 2-year cumulative incidence of major and minor complications in both the study cohorts showed no significant difference. The mean cost of an uncomplicated primary TKA (2019) in government hospital was INR. 85,927; 39.476% of that required in a private setup (INR. 2,17,667).

CONCLUSION

Affordable TKA package in a government funded hospital can produce results comparable to that in a private hospital setup at a reasonably lower cost without increasing the complication rates.

The utility of dithiothreitol treatment of periprosthetic tissues and explanted implants in the diagnosis of prosthetic joint infection

PURPOSE

The methods used for the processing of periprosthetic tissues and explanted implants to improve culture outcome especially in biofilm mediated prosthetic joint infections (PJIs) are still debated upon. Studies have reported that Dithiothreitol (DTT) pretreatment of infected devices gives similar results as sonication. However, none of them evaluated the DTT treatment of periprosthetic tissues and explanted implants in the same cohort. We evaluated the diagnostic utility of DTT treatment of periprosthetic tissue and explanted implants, as compared to the normal saline treatment of periprosthetic tissues and sonication of explanted implants for the diagnosis of PJI.

METHODS

Seventy-three revision arthroplasty cases were prospectively included in this study. Three to five tissue specimens and the explanted implants were collected from each patient. Periprosthetic tissue samples were processed by both normal saline and DTT treatments. Explanted implants were subjected to both DTT treatment and sonication. Musculoskeletal Infection Society (MSIS) PJI criteria was used as the reference standard for the diagnosis of PJI.

RESULTS

Of the 73 cases enrolled, 34 had PJI and 39 were aseptic failures. The sensitivity of DTT treated periprosthetic tissue culture (PTC) and saline treated PTC was similar (66.6% vs 58.8%, P = 0.25). The specificity of both was 100%. Sonication and DTT treatment of explanted implants showed comparable sensitivity (85.3% vs 82.4%) and specificity (100% vs 97.4%), P > 0.99. Compared to DTT treated PTC, culture of DTT treated explanted implants significantly improved the diagnosis of PJI (P = 0.03).

CONCLUSIONS

We could verify that DTT can be used to improve culture outcome in laboratories where biofilm detaching sonication techniques are not available for infected implants. In addition, we showed that it is possible to use DTT for treating tissue biopsies, but larger studies are required to confirm our findings.

Is There a Role for Spacer Exchange in Two-Stage Exchange Arthroplasty for Periprosthetic Joint Infection?

Periprosthetic joint infection (PJI) continues to be one of the most serious complications after hip and knee arthroplasty. The choice of surgical treatment depends on a multitude of factors like chronicity of infection, host factors, and institutional or surgeon experience. Two-stage exchange remains one of the most commonly used technique for chronic PJI in the United States of America. The intended two-stage revision may involve an additional interim procedure where the initial antibiotic cement spacer is removed and a new spacer is inserted. Mostly, the rationale behind spacer exchange is an additional load of local antibiotics before proceeding to reimplantation. There is no conclusive evidence whether a spacer exchange confers additional benefits, yet it delays reimplantation and exposes already fragile patients to the risks and morbidity of an additional surgery.

Spine Infections Reduced at Dedicated Orthopaedics and Spine Hospital

Background

Previous studies stratified postoperative infection risk by patient comorbidities. However, it is unclear whether the incidence varies by surgical approach in a specialized orthopaedic setting. This study aims to compare infection rates and microbiologic characteristics of postoperative spine infections requiring return to the operating room for debridement by hospital setting: a dedicated orthopaedic and spine hospital versus a general hospital serving multiple surgical specialties.

Methods

The study is a retrospective review of prospectively collected data. Procedures performed between March 2006 and August 2008 at the multispecialty university hospital were compared with cases at an orthopaedic specialty hospital from September 2008 through August 2016. The surgeons, residents, and patients were similar, but the operative venue changed in 2008.

Results

The overall general university hospital infection rate was 2.03%, higher than the overall infection rate at the dedicated orthopaedic and spine hospital of 1.31% (P < .0104). The general university infection rate was 2.27% in the final years of practice, compared with 0.91% at the dedicated orthopaedic and spine hospital (P < .0001) during a recent 2-year time frame. Demographic variables did not significantly differ between the 2 settings. The overall proportion of Gram-negative infection rates was not statistically different (21.7% vs 18.6%), despite an increased proportion of Gram-negative infections at the general university hospital following surgery from an anterior approach. Most of the organisms isolated in both facilities were Staphylococcus species. There was no difference in the seasonality of postoperative spine infections in either setting.

Conclusions

In transitioning from a multispecialty university hospital to a dedicated orthopaedic hospital, the incidence of postoperative spine infections was significantly reduced to 0.91%. Despite the change in venue, the proportion of Gram-negative infections (∼20%) following spine surgery did not significantly change. These results suggest improved infection rates during the course of the last 10 years with consistent proportions of Gram-negative infections.

Level of Evidence

3.

Pathogenesis of Staphylococcus epidermidis in prosthetic joint infections: Can identification of virulence genes differentiate between infecting and commensal strains?

BACKGROUND

Staphylococcus epidermidis is a commensal of human skin flora and a frequent causative microorganism in prosthetic joint infections (PJIs). To date, no single marker has been identified to distinguish infecting strains from commensal S. epidermidis populations.

AIM

We aimed to find possible genetic markers to distinguish between the two populations.

METHODS

We analyzed 50 S. epidermidis strains from patients with PJIs, 50 from skin of healthy individuals (commensal strains) and 17 from the surgical field of patients undergoing primary arthroplasty. In these three groups we studied the antimicrobial susceptibility profile, sequence type, biofilm formation, and virulence factors. Strains from the surgical field have not been compared previously with strains from the other two groups.

FINDINGS

S. epidermidis strains from PJI patients were significantly more antibiotic resistant than commensal strains and surgical field strains. A wide variety of sequences types was found in commensal and surgical field strains. The predominant sequence type was ST2 and it was only present in PJI strains (44%). Differences in biofilm production did not differ between populations. Virulence genes sdrF and bhp, the complete ica operon, and the insertion sequence IS256 were significantly predominant in PJI strains. In contrast, embp and hld genes and the mobile element ACME were more prevalent in commensal strains. Surgical field strains could be a valid control group to discriminate between infecting and commensal strains.

CONCLUSION

A combination of characteristic features can differentiate between infecting and commensal S. epidermidis strains in PJI, while a single marker cannot.

Identifying Risk Factors Associated With Postoperative Infection Following Elective Lower-Extremity Total Joint Arthroplasty

This article addresses the importance of identifying risk factors associated with postoperative infection following elective lower-extremity total joint arthroplasty. Specifically, this review discusses risk factors recognized by the American Academy of Orthopaedic Surgeons that should be carefully considered and assessed by the orthopaedic team in collaboration with the primary care provider before proceeding with surgery.