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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.
Methods
A total of 185 patients undergoing a two-stage revision in seven different centres were prospectively enrolled. Of these patients, 93 were randomized to receive microorganism-directed oral antibiotics for three months following reimplantation; 88 were randomized to receive no antibiotics, and four were withdrawn before randomization. Of the 181 randomized patients, 28 were lost to follow-up, six died before two years follow-up, and five with culture negative infections were excluded. The remaining 142 patients were followed for a mean of 3.3 years (2.0 to 7.6) with failure due to a further infection as the primary endpoint. Patients who were treated with antibiotics were also assessed for their adherence to the medication regime and for side effects to antibiotics.
Aims
The aim of this study was to assess the effectiveness of perioperative essential amino acid (EAA) supplementation to prevent rectus femoris muscle atrophy and facilitate early recovery of function after total knee arthroplasty (TKA).
Methods
The study involved 60 patients who underwent unilateral TKA for primary knee osteo-arthritis (OA). This was a double-blind, placebo-controlled, randomized control trial with patients randomly allocated to two groups, 30 patients each: the essential amino acid supplementation (9 g daily) and placebo (lactose powder, 9 g daily) groups. Supplementation and placebo were provided from one week before to two weeks after surgery. The area of the rectus femoris muscle were measured by ultrasound imaging one month before surgery and one, two, three, and four weeks postoperatively. The serum albumin level, a visual analogue knee pain score, and mobility were also measured at each time point. The time to recovery of activities of daily living (ADLs) was recorded. Postoperative nutrition and physiotherapy were identical in both groups.
Aims
The purpose of this study was to determine the impact of the removal of total knee arthroplasty (TKA) from the Medicare Inpatient Only (IPO) list on our Bundled Payments for Care Improvement (BPCI) Initiative in 2018.
Methods
We examined our institutional database to identify all Medicare patients who underwent primary TKA from 2017 to 2018. Hospital inpatient or outpatient status was cross-referenced with Centers for Medicare & Medicaid Services (CMS) claims data. Demographics, comorbidities, and outcomes were compared between patients classified as ‘outpatient’ and ‘inpatient’ TKA. Episode-of-care BPCI costs were then compared from 2017 to 2018.
Aims
A significant percentage of patients remain dissatisfied after total knee arthroplasty (TKA). The aim of this study was to determine whether the sequential addition of accelerometer-based navigation for femoral component preparation and sensor-guided ligament balancing improved complication rates, radiological alignment, or patient-reported outcomes (PROMs) compared with a historical control group using conventional instrumentation.
Methods
This retrospective cohort study included 371 TKAs performed by a single surgeon sequentially. A historical control group, with the use of intramedullary guides for distal femoral resection and surgeon-guided ligament balancing, was compared with a group using accelerometer-based navigation for distal femoral resection and surgeon-guided balancing (group 1), and one using navigated femoral resection and sensor-guided balancing (group 2). Primary outcome measures were Patient-Reported Outcomes Measurement Information System (PROMIS) and Knee injury and Osteoarthritis Outcome (KOOS) scores measured preoperatively and at six weeks and 12 months postoperatively. The position of the components and the mechanical axis of the limb were measured postoperatively. The postoperative range of motion (ROM), haematocrit change, and complications were also recorded.
Aims
Rates of readmission and reoperation following primary total knee arthroplasty (TKA) are under scrutiny due to new payment models, which penalize these negative outcomes. Some risk factors are more modifiable than others, and some conditions considered modifiable such as obesity may not be as modifiable in the setting of advanced arthritis as many propose. We sought to determine whether controlling for hypoalbuminaemia would mitigate the effect that prior authors had identified in patients with obesity.
Methods
We reviewed the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database for the period of January 2008 to December 2016 to evaluate the rates of reoperation and readmission within 30 days following primary TKA. Multivariate logistic regression modelling controlled for preoperative albumin, age, sex, and comorbidity status.
Aims
This study aimed to evaluate the association between the sagittal alignment of the femoral component in total knee arthroplasty (TKA) and new Knee Society Score (2011KSS), under the hypothesis that outliers such as the excessive extended or flexed femoral component were related to worse clinical outcomes.
Methods
A group of 156 knees (134 F:22 M) in 133 patients with a mean age 75.8 years (SD 6.4) who underwent TKA with the cruciate-substituting Bi-Surface Knee prosthesis were retrospectively enrolled. On lateral radiographs, γ angle (the angle between the distal femoral axis and the line perpendicular to the distal rear surface of the femoral component) was measured, and the patients were divided into four groups according to the γ angle. The 2011KSSs among groups were compared using the Kruskal-Wallis test. A secondary regression analysis was used to investigate the association between the 2011KSS and γ angle.
Aims
The extensive variation in axial rotation of tibial components can lead to coronal plane malalignment. We analyzed the change in coronal alignment induced by tray malrotation.
Methods
We constructed a computer model of knee arthroplasty and used a virtual cutting guide to cut the tibia at 90° to the coronal plane. The virtual guide was rotated axially (15° medial to 15° lateral) and with posterior slopes (0° to 7°). To assess the effect of axial malrotation, we measured the coronal plane alignment of a tibial tray that was axially rotated (25° internal to 15° external), as viewed on a standard anteroposterior (AP) radiograph.
Aims
The aims of this study were to determine the effect of osteophyte excision on deformity correction and soft tissue gap balance in varus knees undergoing computer-assisted total knee arthroplasty (TKA).
Methods
A total of 492 consecutive, cemented, cruciate-substituting TKAs performed for varus osteoarthritis were studied. After exposure and excision of both cruciates and menisci, it was noted from operative records the corrective interventions performed in each case. Knees in which no releases after the initial exposure, those which had only osteophyte excision, and those in which further interventions were performed were identified. From recorded navigation data, coronal and sagittal limb alignment, knee flexion range, and medial and lateral gap distances in maximum knee extension and 90° knee flexion with maximal varus and valgus stresses, were established, initially after exposure and excision of both cruciate ligaments, and then also at trialling. Knees were defined as ‘aligned’ if the hip-knee-ankle axis was between 177° and 180°, (0° to 3° varus) and ‘balanced’ if medial and lateral gaps in extension and at 90° flexion were within 2 mm of each other.
Aims
The removal of the cruciate ligaments in total knee arthroplasty (TKA) has been suggested as a potential contributing factor to patient dissatisfaction, due to alteration of the in vivo biomechanics of the knee. Bicruciate retaining (BCR) TKA allows the preservation of the cruciate ligaments, thus offering the potential to reproduce healthy kinematics. The aim of this study was to compare in vivo kinematics between the operated and contralateral knee in patients who have undergone TKA with a contemporary BCR design.
Methods
A total of 29 patients who underwent unilateral BCR TKA were evaluated during single-leg deep lunges and sit-to-stand tests using a validated computer tomography and fluoroscopic imaging system. In vivo six-degrees of freedom (6DOF) kinematics were compared between the BCR TKA and the contralateral knee.
Aims
Postoperative range of movement (ROM) is an important measure of successful and satisfying total knee arthroplasty (TKA). Reduced postoperative ROM may be evident in up to 20% of all TKAs and negatively affects satisfaction. To improve ROM, manipulation under anaesthesia (MUA) may be performed. Historically, a limited ROM preoperatively was used as the key harbinger of the postoperative ROM. However, comorbidities may also be useful in predicting postoperative stiffness. The goal was to assess preoperative comorbidities in patients undergoing TKA relative to incidence of postoperative MUA. The hope is to forecast those who may be at increased risk and determine if MUA is an effective form of treatment.
Methods
Prospectively collected data of TKAs performed at our institution’s two hospitals from August 2014 to August 2018 were evaluated for incidence of MUA. Comorbid conditions, risk factors, implant component design and fixation method (cemented vs cementless), and discharge disposition were analyzed. Overall, 3,556 TKAs met the inclusion criteria. Of those, 164 underwent MUA.
Aims
The purpose of this study was to use pharmacogenetics to determine the frequency of genetic variants in our total knee arthroplasty (TKA) patients that could affect postoperative pain medications. Pharmacogenetic testing evaluates patient DNA to determine if a drug is expected to have a normal clinical effect, heightened effect, or no effect at all on the patient. It also predicts whether patients are likely to experience side effects from medicine. We further sought to determine if changing the multimodal programme based on these results would improve pain control or reduce side effects.
Methods
In this pilot study, buccal samples were collected from 31 primary TKA patients. Pharmacogenetics testing examined genetic variants in genes
Aims
The aim of this study was to analyze the true costs associated with preoperative CT scans performed for robotic-assisted total knee arthroplasty (RATKA) planning and to determine the value of a formal radiologist’s report of these studies.
Methods
We reviewed 194 CT reports of 176 sequential patients who underwent primary RATKA by a single surgeon at a suburban teaching hospital. CT radiology reports were reviewed for the presence of incidental findings that might change the management of the patient. Payments for the scans, including the technical and professional components, for 330 patients at two hospitals were also recorded and compared.
Aims
The purpose of this investigation was to determine the relationship between height, weight, and sex with implant size in total knee arthroplasty (TKA) using a multivariate linear regression model and a Bayesian model.
Methods
A retrospective review of an institutional registry was performed of primary TKAs performed between January 2005 and December 2016. Patient demographics including patient age, sex, height, weight, and body mass index (BMI) were obtained from registry and medical record review. In total, 8,100 primary TKAs were included. The mean age was 67.3 years (SD 9.5) with a mean BMI of 30.4 kg/m2 (SD 6.3). The TKAs were randomly split into a training cohort (n = 4,022) and a testing cohort (n = 4,078). A multivariate linear regression model was created on the training cohort and then applied to the testing cohort . A Bayesian model was created based on the frequencies of implant sizes in the training cohort. The model was then applied to the testing cohort to determine the accuracy of the model at 1%, 5%, and 10% tolerance of inaccuracy.
Aims
It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee arthroplasty (TKA) because conversion surgery to a primary TKA is a less complicated procedure. The purpose of this study was to determine if there is a lower threshold for revising a UKA compared with TKA based on Oxford Knee Scores (OKSs) and range of movement (ROM) at the time of revision.
Methods
We retrospectively reviewed 619 aseptic revision cases performed between December 1998 and October 2018. This included 138 UKAs that underwent conversion to TKA and 481 initial TKA revisions. Age, body mass index (BMI), time in situ, OKS, and ROM were available for all patients.
Aims
Enhanced perioperative protocols have significantly improved patient recovery following primary total knee arthroplasty (TKA). Little has been investigated the effectiveness of these protocols for revision TKA (RTKA). We report on a matched group of aseptic revision and primary TKA patients treated with an identical pain and rehabilitation programmes.
Methods
Overall, 40 aseptic full-component RTKA patients were matched (surgical date, age, sex, and body mass index (BMI)) to a group of primary cemented TKA patients. All RTKAs had new uncemented stemmed femoral and tibial components with metaphyseal sleeves. Both groups were treated with an identical postoperative pain protocol. Patients were followed for at least two years. Knee Society Scores (KSS) at six weeks and at final follow-up were recorded for both groups.
Aims
The aim of this study was to evaluate the ability of a machine-learning algorithm to diagnose prosthetic loosening from preoperative radiographs and to investigate the inputs that might improve its performance.
Methods
A group of 697 patients underwent a first-time revision of a total hip (THA) or total knee arthroplasty (TKA) at our institution between 2012 and 2018. Preoperative anteroposterior (AP) and lateral radiographs, and historical and comorbidity information were collected from their electronic records. Each patient was defined as having loose or fixed components based on the operation notes. We trained a series of convolutional neural network (CNN) models to predict a diagnosis of loosening at the time of surgery from the preoperative radiographs. We then added historical data about the patients to the best performing model to create a final model and tested it on an independent dataset.
Aims
Metaphyseal fixation during revision total knee arthroplasty (TKA) is important, but potentially difficult when using historical designs of cone. Material and manufacturing innovations have improved the size and shape of the cones which are available, and simplified the required bone preparation. In a large series, we assessed the implant survivorship, radiological results, and clinical outcomes of new porous 3D-printed titanium metaphyseal cones featuring a reamer-based system.
Methods
We reviewed 142 revision TKAs in 139 patients using 202 cones (134 tibial, 68 femoral) which were undertaken between 2015 and 2016. A total of 60 involved tibial and femoral cones. Most cones (149 of 202; 74%) were used for Type 2B or 3 bone loss. The mean age of the patients was 66 years (44 to 88), and 76 (55 %) were female. The mean body mass index (BMI) was 34 kg/m2 (18 to 60). The patients had a mean of 2.4 (1 to 8) previous operations on the knee, and 68 (48%) had a history of prosthetic infection. The mean follow-up was 2.4 years (2 to 3.6).
Aims
Metaphyseal cones with cemented stems are frequently used in revision total knee arthroplasty (TKA). However, if the diaphysis has been previously violated, the resultant sclerotic canal can impair cemented stem fixation, which is vital for bone ingrowth into the cone, and long-term fixation. We report the outcomes of our solution to this problem, in which impaction grafting and a cemented stem in the diaphysis is combined with an uncemented metaphyseal cone, for revision TKA in patients with severely compromised bone.
Methods
A metaphyseal cone was combined with diaphyseal impaction grafting and cemented stems for 35 revision TKAs. There were two patients with follow-up of less than two years who were excluded, leaving 33 procedures in 32 patients in the study. The mean age of the patients at the time of revision TKA was 67 years (32 to 87); 20 (60%) were male. Patients had undergone a mean of four (1 to 13) previous knee arthroplasty procedures. The indications for revision were aseptic loosening (80%) and two-stage reimplantation for prosthetic joint infection (PJI; 20%). The mean follow-up was four years (2 to 11).
Aims
Aseptic loosening of the tibial component is a frequent cause of failure in primary total knee arthroplasty (TKA). Management options include an isolated tibial revision or full component revision. A full component revision is frequently selected by surgeons unfamiliar with the existing implant or who simply wish to “start again”. This option adds morbidity compared with an isolated tibial revision. While isolated tibial revision has a lower morbidity, it is technically more challenging due to difficulties with exposure and maintaining prosthetic stability. This study was designed to compare these two reconstructive options.
Methods
Patients undergoing revision TKA for isolated aseptic tibial loosening between 2012 and 2017 were identified. Those with revision implants or revised for infection, instability, osteolysis, or femoral component loosening were excluded. A total of 164 patients were included; 88 had an isolated tibial revision and 76 had revision of both components despite only having a loose tibial component. The demographics and clinical and radiological outcomes were recorded.
Aims
A retrospective longitudinal study was conducted to compare directly volumetric wear of retrieved polyethylene inserts to predicted volumetric wear modelled from individual gait mechanics of total knee arthroplasty (TKA) patients.
Methods
In total, 11 retrieved polyethylene tibial inserts were matched with gait analysis testing performed on those patients. Volumetric wear on the articular surfaces was measured using a laser coordinate measure machine and autonomous reconstruction. Knee kinematics and kinetics from individual gait trials drove computational models to calculate medial and lateral tibiofemoral contact paths and forces. Sliding distance along the contact path, normal forces and implantation time were used as inputs to Archard’s equation of wear to predict volumetric wear from gait mechanics. Measured and modelled wear were compared for each component.
Aims
In patients with a “dry” aspiration during the investigation of prosthetic joint infection (PJI), saline lavage is commonly used to obtain a sample for analysis. The aim of this study was to investigate prospectively the impact of saline lavage on synovial fluid analysis in revision arthroplasty.
Methods
Patients undergoing revision hip (THA) or knee arthroplasty (TKA) for any septic or aseptic indication were enrolled. Intraoperatively, prior to arthrotomy, the maximum amount of fluid possible was aspirated to simulate a dry tap (pre-lavage) followed by the injection with 20 ml of normal saline and re-aspiration (post-lavage). Pre- and post-lavage synovial white blood cell (WBC) count, percent polymorphonuclear cells (%PMN), and cultures were compared.
Aims
Two-stage exchange arthroplasty is the most common definitive treatment for prosthetic joint infection (PJI) in the USA. Complications that occur during treatment are often not considered. The purpose of this study was to analyze complications in patients undergoing two-stage exchange for infected total knee arthroplasty (TKA) and determine when they occur.
Methods
We analyzed all patients that underwent two-stage exchange arthroplasty for treatment of PJI of the knee from January 2010 to December 2018 at a single institution. We categorized complications as medical versus surgical. The intervals for complications were divided into: interstage; early post-reimplantation (three months); and late post-reimplantation (three months to minimum one year). Minimum follow-up was one year. In total, 134 patients underwent a first stage of a two-stage exchange. There were 69 males and 65 females with an mean age at first stage surgery of 67 years (37 to 89). Success was based on the new Musculoskeletal Infection Society (MSIS) definition of success reporting.
Aims
We propose a state-of-the-art temporary spacer, consisting of a cobalt-chrome (CoCr) femoral component and a gentamicin-eluting ultra-high molecular weight polyethylene (UHMWPE) tibial insert, which can provide therapeutic delivery of gentamicin, while retaining excellent mechanical properties. The proposed implant is designed to replace conventional spacers made from bone cement.
Methods
Gentamicin-loaded UHMWPE was prepared using phase-separated compression moulding, and its drug elution kinetics, antibacterial, mechanical, and wear properties were compared with those of conventional gentamicin-loaded bone cement.
Aims
The aim of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement, and smooth titanium alloy to inhibit staphylococci in an in vitro environment, based on the evaluation of the zone of inhibition (ZOI). The hypothesis was that there would be no significant difference in the inhibition of methicillin-sensitive or methicillin-resistant
Methods
A total of 30 beads made of three different materials (tantalum/3D porous titanium and smooth titanium alloy) were bathed for one hour in a solution of 1 g vancomycin in 20 ml of sterile water for injection (bath concentration: 50 mg/mL). Ten 1 cm3 cylinders of antibiotic-loaded cement were also created by mixing standard surgical cement with 1 g of vancomycin in standardized sterile moulds. The cylinders were then placed on agar plates inoculated with MSSA and MRSA. The ZOIs were measured each day and the cylinders were transferred onto a new inoculated plate.
Aims
The aim of this study was to determine if the local delivery of vancomycin and tobramycin in primary total knee arthroplasty (TKA) can achieve intra-articular concentrations exceeding the minimum inhibitory concentration thresholds for bacteria causing acute prosthetic joint infection (PJI).
Methods
Using a retrospective single-institution database of all primary TKAs performed between January 1 2014 and May 7 2019, we identified patients with acute PJI that were managed surgically within 90 days of the initial procedure. The organisms from positive cultures obtained at the time of revision were tested for susceptibility to gentamicin, tobramycin, and vancomycin. A prospective study was then performed to determine the intra-articular antibiotic concentration on postoperative day one after primary TKA using one of five local antibiotic delivery strategies with tobramycin and/or vancomycin mixed into the polymethylmethacrylate (PMMA) or vancomycin powder.
Aims
Arthrodesis is rarely used as a salvage procedure for patients with a chronically infected total knee arthroplasty (TKA), and little information is available about the outcome. The aim of this study was to assess the reliability, durability, and safety of this procedure as the definitive treatment for complex, chronically infected TKA, in a current series of patients.
Methods
We retrospectively identified 41 patients (41 TKAs) with a complex infected TKA, who were treated between 2002 and 2016 using a deliberate, two-stage knee arthrodesis. Their mean age was 64 years (34 to 88) and their mean body mass index (BMI) was 39 kg/m2 (25 to 79). The mean follow-up was four years (2 to 9). The extensor mechanism (EM) was deficient in 27 patients (66%) and flap cover was required in 14 (34%). Most patients were host grade B (56%) or C (29%), and limb grade 3 (71%), according to the classification of McPherson et al. A total of 12 patients (29%) had polymicrobial infections and 20 (49%) had multi-drug resistant organisms; fixation involved an intramedullary nail in 25 (61%), an external fixator in ten (24%), and dual plates in six (15%).
Aims
The integrity of the soft tissue envelope is crucial for successful treatment of infected total knee arthroplasty (TKA). The purpose of this study was to evaluate the rate of limb salvage, infection control, and clinical function following microvascular free flap coverage for salvage of the infected TKA.
Methods
We retrospectively reviewed 23 microvascular free tissue transfers for management of soft tissue defects in infected TKA. There were 16 men and seven women with a mean age of 61.2 years (39 to 81). The median number of procedures performed prior to soft tissue coverage was five (2 to 9) and all patients had failed at least one two-stage reimplantation procedure. Clinical outcomes were measured using the Knee Society Scoring system for pain and function.
