Aims. The management of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is challenging. The correct antibiotic management remains elusive due to differences in epidemiology and resistance between countries, and reports in the literature. Before the efficacy of surgical treatment is investigated, it is crucial to analyze the bacterial strains causing PJI, especially for patients in whom no organisms are grown. Methods. A review of all revision TKAs which were undertaken between 2006 and 2018 in a tertiary referral centre was performed, including all those meeting the consensus criteria for PJI, in which organisms were identified. Using a cluster analysis, three chronological time periods were created. We then evaluated the antibiotic resistance of the identified bacteria between these three clusters and the effectiveness of our antibiotic regime. Results. We identified 129 PJIs with 161 culture identified bacteria in 97 patients. Coagulase-negative staphylococci (CNS) were identified in 46.6% cultures, followed by Staphylococcus aureus in 19.8%. The overall resistance to antibiotics did not increase significantly during the study period (p = 0.454). However, CNS resistance to teicoplanin (p < 0.001), fosfomycin (p = 0.016), and tetracycline (p = 0.014) increased significantly. Vancomycin had an 84.4% overall sensitivity and 100% CNS sensitivity and was the most effective agent. Conclusion. Although we were unable to show an overall increase in antibiotic resistance in organisms that cause PJI after TKA during the study period, this was not true for CNS. It is concerning that resistance of CNS to new antibiotics, but not vancomycin, has increased in a little more than a decade. Our findings suggest that referral centres should continuously monitor their bacteriological analyses, as these have significant implications for prophylactic treatment in both primary arthroplasty and revision arthroplasty for PJI. Cite this article: Bone Joint J 2021;103-B(6 Supple A):171–176

Introduction. Management of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is a challenging task. Antibiotic management remains elusive due to differences in epidemiology and resistance between countries and reports. Increasing resistance of bacteria is a concern. The aim of this study was to investigate the development of antibiotic resistance of main causative bacteria in a single center. Methods. A retrospective review of all revision TKA between 2006 and 2018 in a tertiary referral center was performed. Included were cases meeting the consensus criteria for PJI with at least two positive cultures. Three chronological groups were created using a two-step cluster analysis. Results. In 129 cases of PJI there were 161 different bacteria identified by growth in culture. Of all bacteria 76.4% were gram positive, 23.6% were gram negative. Coagulase-negative Staphylococci (CNS) were diagnosed in 46.6% cultures, followed by Staphylococcus aureus in 19.8% of cultures. Overall antibiotic resistance (p=0.454) and Staphylococcus aureus resistance (p=0.788) have not increased during the study period. CNS resistance to teicoplanin (4% to 44%; p<0.001), fosfomycin (16% to 44%, p=0.016) and tetracycline (0% to 28%, p=0.014) increased significantly. Vancomycin had an 84.4% overall sensitivity and 100% CNS sensitivity and remained the most effective agent. Conclusion. The increasing resistance to several antibiotics over a little more than a decade is concerning. This study suggests that referral centres should continuously monitor obtained cultures as this has significant implications for both prophylactic treatment in primary as well as empirical antibiotic treatment in PJI. Resistance profiles may differ between centres and are subject to dynamic changes

Aims. The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach. Methods. A total of 60 surgeons from 11 countries were invited to develop consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest within patellar instability. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered to be unanimous. Results. Of 27 questions and statements on patellar instability, three achieved unanimous consensus, 14 achieved strong consensus, five achieved consensus, and five did not achieve consensus. Conclusion. The statements that reached unanimous consensus were that an assessment of physeal status is critical for paediatric patients with patellar instability. There was also unanimous consensus on early mobilization and resistance training following nonoperative management once there is no apprehension. The statements that did not achieve consensus were on the importance of immobilization of the knee, the use of orthobiologics in nonoperative management, the indications for MPFC repair, and whether a vastus medialis oblique advancement should be performed. Cite this article: Bone Joint J 2023;105-B(12):1259–1264

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The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes.

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The antidiabetic agent metformin inhibits fibrosis in various organs. This study aims to elucidate the effects of hyperglycaemia and metformin on knee joint capsule fibrosis in mice.

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The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross-linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient-reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients.

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The primary objective of this study was to compare the five-year tibial component migration and wear between highly crosslinked polyethylene (HXLPE) inserts and conventional polyethylene (PE) inserts of the uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary objectives included clinical outcomes and patient-reported outcome measures (PROMs).

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Aseptic loosening is the most common cause of failure following cemented total knee arthroplasty (TKA), and has been linked to poor cementation technique. We aimed to develop a consensus on the optimal technique for component cementation in TKA.

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The tibial component of total knee arthroplasty can either be an all-polyethylene (AP) implant or a metal-backed (MB) implant. This study aims to compare the five-year functional outcomes of AP tibial components to MB components in patients aged over 70 years. Secondary aims are to compare quality of life, implant survivorship, and cost-effectiveness.

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The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery.

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This multicentre retrospective observational study’s aims were to investigate whether there are differences in the occurrence of radiolucent lines (RLLs) following total knee arthroplasty (TKA) between the conventional Attune baseplate and its successor, the novel Attune S+, independent from other potentially influencing factors; and whether tibial baseplate design and presence of RLLs are associated with differing risk of revision.

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The primary aim of this study was to compare the migration of the femoral and tibial components of the cementless rotating platform Attune and Low Contact Stress (LCS) total knee arthroplasty (TKA) designs, two years postoperatively, using radiostereometric analysis (RSA) in order to assess the risk of the development of aseptic loosening. A secondary aim was to compare clinical and patient-reported outcome measures (PROMs) between the designs.

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The purpose of this study was to compare reoperation and revision rates of double plating (DP), single plating using a lateral locking plate (SP), or distal femoral arthroplasty (DFA) for the treatment of periprosthetic distal femur fractures (PDFFs).

Introduction. The association between CoCr joint replacements and adverse tissue reactions has led to increased interest in alternative materials that are both biocompatible and wear-resistant. One approach is to manufacture components from titanium alloys with a hardened articulating surface to increase resistance to scratching and surface damage caused by third-body particles. In this study we investigate methods for characterizing the performance of retrieved TiAlV components with nitrogen-hardened bearing surfaces. Methods. Surface-hardened titanium knee implants (TiNidium) were retrieved from 18 patients (7.7 ±6.8 years) at revision surgery. After processing, the bearing surface of each component was characterized by stereomicroscopy, SEM, optical profilometry, and incremental nano-indentation hardness testing. A case-matched set of 18 CoCr components (6.7 ±5.6 years) were characterized for comparison. Results. Each bearing surface was graded for microscopic damage classified as pitting, abrasion, scratching, and burnishing using an Injury Severity Score. The components were divided into slight, average, and severe damage groups based on the resulting ISS scores. Representative specimens from each group were then subjected to SEM imaging, 12 roughness measurements, and 3 incremental nano-indentation hardness tests. Conclusion. There was no difference between the severity of surface damage of the hardened and CoCr components ((p=0.67); Table 1). The rate of surface damage was greatest in the first 2 years then decreased exponentially (Figure 1). Surface roughness (Ra) values were similar for both groups (TiAlV: 0.771um; CoCr: 0.884um) but decreased with the severity of visual damage in the TiNidium implants due to secondary burnishing of scratches. The hardness of the TiNidium implants varied with depth below the bearing surface in contrast to the CoCr controls in which hardness did not vary with depth (Figure 2). Our findings show that multiple complementary methods of are needed to adequately characterize the performance of surface hardened implants. For figures, tables, or references, please contact authors directly

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The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

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The aim of this study was to evaluate medium-term outcomes and complications of the S-ROM NOILES Rotating Hinge Knee System (DePuy, USA) in revision total knee arthroplasty (rTKA) at a tertiary unit.

Introduction. Antibiotic-impregnated bone cement (AIBC) has been used for decades to treat and prevent post-operative infections in joint arthroplasty. Local delivery of antibiotics may theoretically have a bactericidal effect, however evidence supporting this is controversial and literature suggests its prophylactic use in primary total knee arthroplasty (TKA) is seldom justified. With evolving standards of care, historical data is no longer relevant in addressing the efficacy of AIBC in the contemporary TKA. The purpose of this study was to evaluate outcomes following primary TKA using AIBC and regular non-AIBC by comparing rates of surgical site infection (SSI) and prosthetic joint infection (PJI). Methods. A retrospective review was conducted of all cemented primary TKA procedures from a large institutional database between January 1, 2015 and December 31st, 2016. This identified 6,073 cases, n=2,613 in which AIBC was used and n=3,460 cases using bone cement without antibiotics. Patients were stratified into low risk and high-risk groups based on age (>65 years), BMI (>40), and Charlson Comorbidity Index (CCI; >3). Medical records were reviewed for diagnoses of SSI (skin and superficial wound infections) and PJI (deep joint infections requiring surgery) over a 2-year postoperative period. Univariate analysis and multivariate regression models were used to ascertain the effects of cement type, patient factors (age, gender, BMI, CCI), operative time, and length of stay on infection rates. Additionally, mixed models (adjusted for gender, age, race, BMI, and CCI) were built to account for surgeon variability. Results. The use of AIBC and risk group distributions were equal across the study period and no collinearity was found between the study variables. The SSI rate was 3.0% and the PJI rate was 0.8% in the total study population. Univariate analysis showed there was no significant difference in SSI rates with AIBC compared to non-AIBC (3.3% vs. 2.8%, p=0.278) or in PJI rates (1.0% vs. 0.7%, p=0.203). Multivariate logistic regression analysis adjusted for patient factors, operative time, and length of stay showed no significant difference in SSI rates with a procedure using AIBC compared to non-AIBC (OR=0.90; 95% CI, 0.66–1.23; p=0.515) and no significant difference in PJI rates (OR=1.01; 95% CI, 0.55–1.84; p=0.984). Mixed models also showed no difference in PJI rates with AIBC use after adjusting for surgeon variability as well as patient factors (gender, race, age, BMI, and CCI). Discussion. Prophylactic use of AIBC in primary TKA is not without consequence when considering the significant increase in cost and its potential side effects, namely organism specific antibiotic resistance and mechanical loosening. This study shows that even when adjusted for patient factors, procedure-related factors, and length of stay, there is no clinically significant decrease in infection rates with the use of AIBC in primary TKAs

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The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs).

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Intra-articular administration of antibiotics during primary total knee arthroplasty (TKA) may represent a safe, cost-effective strategy to reduce the risk of acute periprosthetic joint infection (PJI). Vancomycin with an aminoglycoside provides antimicrobial cover for most organisms isolated from acute PJI after TKA. However, the intra-articular doses required to achieve sustained therapeutic intra-articular levels while remaining below toxic serum levels is unknown. The purpose of this study is to determine the intra-articular and serum levels of vancomycin and tobramycin over the first 24 hours postoperatively after intra-articular administration in primary cementless TKA.

Introduction. In major orthopaedic departments, typically several total knee systems are used. Each system requires several sets of instruments, each set with many trays of complicated and expensive parts. The logistics and costs of maintainance are considerable. Our overall goal is to investigate the feasibility of autoclavable single-use 3D printed instruments made from a polymeric material, used for any type of total knee design. The procedure will be standardized and adjustments easy to implement. Each set will be packaged individually, and used for a single case. There are many aspects to this study; in this part, the aims are to identify suitable materials for autoclavability and strength, and then to compare the accuracy of a novel design of 3D printed tibial cutting guide with a current metallic guide. Methods. Test samples were designed to simulate shapes in current instruments, such as mating pegs and holes, threaded screws, and slotted blocks. Each set was produced in biocompatible materials, ABS-M30i, VeroClear (MED610), Ultem1010, and Nylon 12. Each part was laser scanned, and then imaged virtually using a reverse engineering software (GeoMagic). Manual measurements of key dimensions were also made using calipers. The parts were autoclaved using a standardized protocol, 30 minutes at 250° F. All parts were re-scanned and measured to determine any changes in dimensions. To test for strength and abrasion resistance, the slotted blocks were pinned to sawbones model tibias, and an oscillating saw used to cut through the slot. A compact 3D printed tibial cutting guide was then designed which fitted to the proximal tibia and allowed varus-valgus, tibial slope and height adjustments. A small laser attached to the guide projected to a target at the ankle. Tests were made on 20 sawbones, and compared with 20 with a standard metal cutting guide. Digitization was used to measure the angles of the cuts. Results. Prior to autoclaving, the mating parts of all parts were congruent, except for Nylon 12 which had processing debris in slots and screw threads. The ABS-M30i shapes became grossly deformed after autoclaving. The other materials experienced only small changes in dimensions without loss of overall shape, but the slot of the Nylon 12 block was stenotic, 1.4 mm compared to 0.9 mm before autoclaving. In saw blade testing, the VeroClear block fractured through the corner of the slot, while the Nylon 12 block deformed due to heating. The Ultem1010 block produced a small amount of debris, but maintained its shape without any structural damage. In the tests of the tibial cutting guide the 3D printed laser-guided tibial cutting guide resulted in a mean absolute error of 1.72°±1.31° and 1.19°±0.93°, for the tibial slope and varus-valgus respectively. For the conventional guides, these values were 3.78°±1.98° and 2.33°±0.98°, respectively. These measurements were found to be statistically significant with p values of 0.004 and 0.001, respectively. Conclusions. Thus far, apart from patient specific cutting guides and trial components, 3D printing has had limited applications in total knee surgery. As cost containment remains prominent, the use of 3D printing to produce standardized instruments may become viable. These instruments would not require pre-op planning such as CT or MRI, yet allow patient-specific angular settings. Our results indicated that Ultem1010 is a promising material, while a novel tibial cutting guide showed higher accuracy than standard, as well as being quicker to use. These initial tests indicated the viability of 3D printed instruments, but further work will include design and evaluation of the other cutting guides, manufacturing logistics such as in-house or company- based, and economics