Revision Knee Arthroplasty Research Articles

Knee joint dislocations-Current epidemiology and treatment in Germany.

Knee joint dislocations, though rare, present significant challenges due to potential complications like vascular and nerve damage, and are known to be often linked to sports injuries, accidents and obesity. This study aims to analyse the epidemiology, incidence and treatment approaches for knee dislocations in Germany from 2019 to 2022. This retrospective cohort study utilized data from the German Institute for the Hospital Remuneration System to examine knee dislocation cases across German medical institutions. Patient data coded under International Statistical Classification of Diseases and Related Health Problems 10 for 'knee dislocation' enabled detailed analysis by age, sex and surgical procedures categorized by operation and procedure codes. The Patient Clinical Complexity Level (PCCL) assessed complication severity. Analysis of 1643 knee dislocation cases revealed an incidence rate of 0.44-0.54 per 100,000 inhabitants annually. During the years 2020 and 2021, there were fewer cases of knee dislocations. Male patients comprised 50%-56% of cases, with an average hospital stay of 11 days. Most cases were PCCL 0 (62%-72%) and predominantly affected patients aged 18-29 years. Anterior tibial dislocations were common among classified cases. Injuries included ligament ruptures, meniscus lesions and grade I soft-tissue injuries. Patients with pre-existing knee prostheses constituted 0%-16% annually. Treatment involved closed reduction, external fixation and surgeries like capsuloligamentous reconstructions and arthroscopic procedures. Revision knee arthroplasty was required in 2%-9% of cases, with obesity rates up to 7%. This study provides valuable insights into the epidemiology, incidence and treatment of knee dislocations in Germany, with a focus on demographic risk factors, treatment complexities and the impact of obesity and knee prostheses. The findings emphasize the importance of specialized care in larger hospitals, comprehensive management of concomitant injuries and the need for improved coding accuracy. Future research should aim to refine treatment protocols. Level III.

Study of neuromuscular activity in preparation for revision knee arthroplasty

The results of an electromyographic study of 13 patients, aged 50–87 years, with aseptic instability of the components of a knee joint endoprosthesis at the stage of preparation for revision arthroplasty, who were treated at the Republican Scientific and Practical Center of Trauma tology and Orthopedics in the period from 2013 to 2020, were analyzed. To assess the orthopedic status, we used: clinical examination, radiography of the knee joint in 2 standard and axial projections, topogram and CT scan. lectrophysiological studies provide important information for elucidating the etiopathogenesis of knee joint endoprosthesis instability. One of the causes of instability may be an imbalance in the activity of the flexor and extensor muscles that develops during walking, subsequently leading to periprosthetic osteolysis, which occurs as a response to the formation of wear and tear products of the components of the endoprosthesis.

Construction and evaluation of a combined diagnostic model for chronic periprosthetic joint infection based on serological tests

BackgroundEarly diagnosis of chronic periprosthetic joint infection (CPJI) is crucial for ensuring effective treatment and improving patient outcomes. However, many auxiliary diagnostic tests are challenging to implement on a large scale due to economic and technical constraints, making CPJI diagnosis difficult. This study aims to design and validate a combined diagnostic model based on commonly used serological tests to evaluate its diagnostic value for CPJI and develop a diagnostic nomogram.MethodsA retrospective study from January 2019 to February 2024 involving 170 patients undergoing knee and hip arthroplasty revision for CPJI and aseptic loosening (AL) was conducted across two medical centers. These patients were divided into the training set and validation set. Patients were categorized into CPJI and AL groups based on infection status. Serological tests conducted upon admission were collected, and single-factor and multi-factor logistic regression analyses were used to identify independent diagnostic factors for early infection. These factors were integrated to construct a nomogram model. The model's performance was evaluated using the receiver operating characteristic area under the curve (AUC), Hosmer–Lemeshow test, decision curve analysis (DCA), and calibration curve, with external validation conducted on the validation set.ResultsMultivariate logistic regression analysis showed that C-reactive protein (CRP), procalcitonin (PCT), and Platelet count/mean platelet volume ratio (PVR) were independent diagnostic factors for CPJI (p < 0.05). The AUCs for diagnosing CPJI using these individual factors were 0.806, 0.616, and 0.700 (p < 0.05), respectively, while their combined detection achieved an AUC of 0.861 (p < 0.05). The DCA clinical impact curve shows the combined model has good clinical utility when the threshold probability of infection presence is between 0.16 and 0.95. Similar results were obtained in the external validation cohort, with the combined detection having an AUC of 0.893.ConclusionThe combined diagnostic model of CRP, PCT, and PVR significantly improves the The combined diagnostic model of CRP, PCT, and PVR significantly improves the diagnostic performance for CPJI compared to individual serum biomarkers. It exhibits good sensitivity, specificity, and clinical applicability, providing valuable references for CPJI diagnosis.

Epidemiology, Classification and Treatment of Femur and Tibia Fractures around Total Knee Arthroplasty (Literature Review)

Summary. Periprosthetic fractures around total knee arthroplasty (TKA) are difficult to treat due to complex fracture morphology, high proportions of injuries associated with osteopenia, and the variability of injury patterns. Periprosthetic fractures associated with TKA are defined as fractures around the knee joint (femur, tibia, or patella) occurring within 5 cm of the intramedullary stem of the prosthesis or 15 cm of the joint. The incidence is estimated to be between 0.3% and 2.5% after primary TKA and up to 28% after revision TKA. There are several surgical and nonsurgical risk factors associated with postoperative periprosthetic fractures. Distal femoral periprosthetic fractures following TKA are the most common and reported to occur in 0.2–1.8% of patients after primary TKA. Tibial periprosthetic fractures have a reported prevalence of 0.07–0.1% in primary and 0.36% in revision knee arthroplasties. Patella fractures are the second most common periprosthetic fractures following TKA, with prevalence ranging from 0.68% to 1.19%, and are usually associated with a resurfaced patella. Several classification systems of periprosthetic fractures around TKA have been published and some treatment recommendations have been provided. However, most systems are subject to criticism and use different classification systems for the tibia, patella, and the femur.A variety of treatment methods are available for periprosthetic fractures. Conservative treatment can include protected weight bearing, splinting, or traction. Surgical treatment commonly involves closed intramedullary nailing or open reduction and internal fixation by plates. In cases of significant bone loss, a revision TKA may be indicated. In general, treatment must be guided based on the stability of the implant and the remaining bone quality, as determined by the presence of osteolysis and the location of the fracture.

Unexpected positive cultures in aseptic revision hip and knee arthroplasty.

The outcomes of patients with unexpected positive cultures (UPCs) during revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) remain unknown. The objectives of this study were to establish the prevalence and infection-free implant survival in UPCs during presumed aseptic single-stage revision THA and TKA at mid-term follow-up. This study included 297 patients undergoing presumed aseptic single-stage revision THA or TKA at a single treatment centre. All patients with at least three UPCs obtained during revision surgery were treated with minimum three months of oral antibiotics following revision surgery. The prevalence of UPCs and causative microorganisms, the recurrence of periprosthetic joint infections (PJIs), and the infection-free implant survival were established at minimum five years' follow-up (5.1 to 12.3). Of the 297 patients undergoing aseptic revisions, 37 (12.5%) had at least three UPCs obtained during surgery. The UPC cohort included 23 males (62.2%) and 14 females (37.8%), with a mean age of 71.2 years (47 to 82). Comorbidities included smoking (56.8%), hypertension (48.6%), diabetes mellitus (27.0%), and chronic renal impairment (13.5%). The causative microorganisms included Staphylococcus epidermidis (49.6%), Bacillus species (18.9%), Micrococcus species (16.2%), and Cutibacterium acnes (16.2%). None of the study patients with UPCs developed further PJIs or required further surgical intervention during follow-up. The prevalence of UPCs during presumed aseptic revision THA and TKA was 12.5%. The most common causative microorganisms were of low virulence, and included S. epidermidis, Bacillus species, Micrococcus species, and C. acnes. Microorganism-specific antibiotic treatment for minimum three months' duration of UPCs in presumed aseptic revision arthroplasty was associated with excellent infection-free implant survival at mid-term follow-up.

Perioperative Glycemic Variability Influences Infection Rates Differently Following Revision Hip and Knee Arthroplasty

IntroductionRecent investigations have determined that abnormal postoperative glycemia following primary total joint arthroplasty is associated with adverse events. Our study aimed to determine if hyperglycemia and glycemic variability following aseptic revision total joint arthroplasty (rTJA) were associated with periprosthetic joint infection (PJI) within two years postoperatively. MethodsA retrospective review was performed of 2,208 patients within a single institution undergoing aseptic rTJA from 2012 to 2019. Postoperative glucose values were recorded. Glycemic variability was measured via three parameters: coefficient of variation (%CV), mean amplitude of glycemic excursions (MAGE), and J-index. Logistic regression analyses were performed to examine associations with PJI at 90-day, 1-, and 2-year follow-up. ResultsIn revision hips, all glycemic measures were not associated with PJI at any timepoint in logistic regression analyses, except for MAGE, which predicted PJI at one year (P = 0.045); body mass index (BMI) was the only factor associated with PJI at all timepoints in all models. In revision knees, all glycemic measures were not associated with PJI at any timepoint in logistic regression analyses; however, PJI rates differed between diabetics and non-diabetics at all time-points (P < 0.05). ConclusionsOur findings illustrate that decreasing preoperative BMI and postoperative glycemic variability may be critical in reducing PJI rates in revision hips. Furthermore, patients who have diabetes should be counseled that they remain at higher risk of PJI regardless of perioperative glucose control after revision knee surgery.

Staged revision of the infected knee arthroplasty and endoprosthesis.

Periprosthetic joint infection (PJI) is a challenging complication of any arthroplasty procedure. We reviewed our use of static antibiotic-loaded cement spacers (ABLCSs) for staged management of PJI where segmental bone loss, ligamentous instability, or soft-tissue defects necessitate a static construct. We reviewed factors contributing to their failure and techniques to avoid these complications when using ABLCSs in this context. A retrospective analysis was conducted of 94 patients undergoing first-stage revision of an infected knee prosthesis between September 2007 and January 2020 at a single institution. Radiographs and clinical records were used to assess and classify the incidence and causes of static spacer failure. Of the 94 cases, there were 19 primary total knee arthroplasties (TKAs), ten revision TKAs (varus-valgus constraint), 20 hinged TKAs, one arthrodesis (nail), one failed spacer (performed elsewhere), 21 distal femoral endoprosthetic arthroplasties, and 22 proximal tibial arthroplasties. A total of 35/94 patients (37.2%) had spacer-related complications, of which 26/35 complications (74.3%) were because of mechanical failure of the spacer construct, while 9/35 (25.7%) were due to recurrence of infection. Risk factors for internal failure were a construct where the total intramedullary spacer length was less than twice the length of the central osseous defect (p = 0.009), where proximal or distal intraosseous spacer contact was < 10%, and after tibial tubercle osteotomy (p = 0.005). The incidence of spacer complications significantly increased the time to second stage: mean 157 days (42 to 458) in those without complications versus 227 days (11 to 528) with complications (p = 0.014). The failure rate of static antibiotic-loaded cement spacers is much higher than anticipated. Complications of the spacer significantly increased the time to second-stage revision. The risk of mechanical failure is significantly increased if the spacer is less than double the size of the segmental defect, or if inadequate reinforcement is inserted into the residual bone. These findings serve as a guide for surgeons to avoid mechanical complications with static spacers.

The push-through total femoral prosthesis for revision of a total hip or knee replacement with extreme bone loss.

The aim of the present study was to assess outcomes of using the push-through total femoral prothesis (PTTF) for revision total hip replacement with extreme bone loss. 10 consecutive patients who received PTTF between 2012 and 2018 for revision hip arthroplasty were included in the study. Primary functional outcomes were assessed using Harris Hip Score (HHS), Toronto Extremity Salvage Score (TESS) and Musculoskeletal Tumor Society (MSTS) scores. Range of motion, complications, and ambulatory status were also recorded to assess secondary outcomes. 2 of 10 patients underwent surgery with PTTF for both knee and hip arthroplasty revision. The mean time between index surgery and PTTF was 15 years (3-32 yrs). Acetabular components were revised in 6 of 10 patients during PTTF application. After a mean follow-up of 5.9 years, hip dislocations occurred in 3 patients. All of the dislocated hips were ones with retained conventional non-constrained acetabular bearings. Patient satisfaction was high (MSTS: 67%, HHS: 61.2%, TESS 64.6%) despite high re-operation rate (40%) and minor postoperative problems. PTTF should be considered for hip and knee arthroplasty revision procedures in patients with an extreme bone defect. Consistent usage of constrained liners should be considered to avoid hip dislocation, which was our main problem following the procedure.

No shortening of the patellar tendon during two-stage total knee arthroplasty revision using articulating spacers.

Surgical techniques in two-stage revision total knee arthroplasty(rTKA) include the use of articulating spacers and static spacers. Shortening of the patellar tendon could be a reason for inferior functional outcomes in two-stage septic rTKA. The aim of this study was to determine if articulating spacers also have negative effects on the extensor mechanism in rTKA. This retrospective study includes 65 consecutive patients (23 women, 42 men, age 71.3 ± 1.2; range, 51.2-88.6 years) undergoing septic two-stage rTKA using an articulating spacer between 2014 and 2021 in a single orthopedic center. For all patients, calibrated true lateral radiographs before total knee arthroplasty (TKA) explantation (T0), directly after TKA explantation (T1), shortly before TKA reimplantation (T2) and 6-8 days after TKA reimplantation (T3) were used to calculate the modified Insall Salvati ratio (mISR). Overall, the mISR decreased significantly immediately after explantation (T0 vs. T1, p = 0.002) from 1.43 ± 0.03 to 1.36 ± 0.03 and remained stable until T2 (1.37 ± 0.02, p = 0.74). Following TKA reimplantation, the mISR increased again to 1.43 ± 0.03 (T3). There were no significant differences between T0 and T3 (p = 0.88). Six out of 65 patients (9%) experienced patellar tendon shortening > 10% at T3. Septic two-stage revision TKA using an articulating spacer does not lead to patellar tendon shortening in the majority of cases. This study suggests that one reason for the improved range of motion after reimplantation may be the use of articulating spacers compared to static spacers.

Comparison of Externally Transferred and Self-Recruited Patients with Hip and Knee Revision Arthroplasty at a Certified Maximum-Care Arthroplasty Center (ACmax).

According to the guidelines of the EndoCert initiative, certified maximum-care arthroplasty centers (ACmax) are obliged to admit patients from certified arthroplasty centers (AC) if these patients need to be transferred to the more specialized ACmax due to difficult replacement and revision procedures as well as after complications in primary care that are beyond the expertise of the smaller centers. This study investigated whether the cohort of transferred patients differed from the patients directly recruited at the ACmax for factors such as severity of diagnosis, comorbidities or outcome. The aim was to determine whether transferred patients increased the resource requirements for the ACmax. A total of 136 patients were included in the retrospective study and analyzed in terms of case severity, length of hospital stays (LOS), Diagnosis-Related Group charges, readmission rate and concomitant diseases. All patients were followed for up to 12 months after the initial hospital stay. There were significant differences between the groups of transferred and self-recruited patients. For example, transferred patients had a higher Patient Clinical Complexity Level (PCCL). Similarly, the increased Case Mix Index (CMI) of transferred patients indicated more intensive care during the inpatient stay. The higher values for the comorbidity indices also supported these results. This had an impact on the LOS and overall costs, too. The differences between the groups were also reflected by adverse events during the one-year follow-up. The higher percentage of patients with septic revisions, whose treatment is especially demanding, among transferred patients aggravated the differences even further. Thus, transferred patients were associated with increased resource requirements for the ACmax. While it serves patients' safety to transfer them to an ACmax with specialized expertise and greater structural quality, the care of transferred patients ties up considerable resources at the ACmax that might only be insufficiently reimbursed by the generalized tariffs.

Revision Knee Arthroplasties Done at Muhimbili Orthopaedic Institute, Tanzania, between 2007 and 2018

Revision Knee Arthroplasties Done at Muhimbili Orthopaedic Institute, Tanzania, between 2007 and 2018

Genetically predicted effects of 10 sleep phenotypes on revision of knee arthroplasty: a mendelian randomization study

BackgroundAccumulating evidence has suggested that sleep disturbances and disorders are common in patients who undergo knee arthroplasty. Revision surgery represents one of the most catastrophic outcomes of knee arthroplasty. However, it remains unclear whether sleep traits are the causes or consequences of knee arthroplasty revision. This study aimed to genetically examine the relationships between sleep traits and knee arthroplasty revision.MethodsTo determine the causal relationship between sleep traits and knee arthroplasty revision, we employed two-sample Mendelian randomization (MR) using summary statistics from the largest publicly available genome-wide association studies (GWASs). The MR design uses genetic variants as instrumental variables to help separate causal relationships from non-causal associations. The main analyses included an inverse variance weighted (IVW) meta-analysis to obtain primary effect estimates. Sensitivity analyses involving the weighted median approach and MR-Egger regression were also conducted to check for potential pleiotropic biases. Numerous complementary sensitivity analyses were also performed to identify statistically significant causal correlations when there were horizontal pleiotropy and heterogeneity across variants. Finally, a reverse MR analysis was performed to evaluate the possibility of reverse causation.ResultsIn the absence of heterogeneity and horizontal pleiotropy, the IVW method revealed that genetically-predicted short sleep duration short sleep duration (average sleep duration of 24 h is 6 h or less) was positively correlated with the risk of knee arthroplasty revision (odds ratio = 1.03, 95% confidence interval = 1.01–1.05, and P = 0.003), while the association between genetically-predicted long sleep duration and knee arthroplasty was negative. The reverse MR analysis did not yield evidence supporting reverse causality relation between knee arthroplasty revision and sleep phenotypes.ConclusionThis research indicated that, of the 10 sleep phenotypes we analyzed, only sleep duration was causally associated with knee arthroplasty revision. These discoveries added to the understanding of the role of sleep traits in the etiology of knee arthroplasty revision, which might further expand our insights into the prevention of knee arthroplasty revision.

Survivorship of Primary NexGen Knee Replacement: Comparing Cementless Trabecular Metal to Other Designs of Tibial Component.

The impact of cementless trabecular metal (TM) implants on implant survivorship are not well delineated. This study compares primary total knee arthroplasty (TKA) revision rates of cemented knee replacements with two cementless knee replacement designs-cementless TM and a non-TM cementless design. Data from a national registry queried TKA procedures performed for osteoarthritis from 1999 to 2020. The risk of revision of Zimmer NexGen TKA using cementless TM, cementless non-TM, and cemented non-TM were compared. Analyses included Kaplan-Meier estimates of survivorship and Cox hazard ratios (HR), stratified by age and gender. Cementless TM components had higher risks of revision compared with cementless non-TM implants (HR = 1.49; p ≤ 0.001). Cementless TM implants showed higher risks of revision compared with cemented non-TM prostheses for the first 2 years (HR = 1.75, p < 0.001). Non-TM prostheses posed equal risk of revision for cementless and cemented fixations (HR = 0.95, p = 0.522). Patients aged 55 to 64 years and 65 to 74 years had a higher risk of revision for cementless TM compared with cementless non-TM (HR = 1.40, p = 0.033 and HR = 1.79, p < 0.001, respectively) and cemented non-TM implants (HR = 1.51, p < 0.001 and HR = 1.54, p < 0.001, respectively). The study shows there is an increased risk of revision with TM cementless implants for patients aged 55 to 74 years. These results do not support the use of TM tibial implants for patients of this age group for primary TKA.

Reduced Knee Flexion Strength 18 Years After ACL Reconstruction With Hamstring Tendon Versus Patellar Tendon

Background: Bone–patellar tendon–bone (BPTB) and double-looped semitendinosus and gracilis (hamstring) grafts are commonly used for anterior cruciate ligament (ACL) reconstruction. Short-term and midterm studies show little or no differences between the 2 grafts; however, there are only a few long-term studies to compare results between the 2 grafts. Purpose: To compare the results after using either BPTB grafts or hamstring tendon grafts 18 years after ACL reconstruction. Study Design: Randomized controlled trial; Level of evidence 2. Methods: A total of 114 patients with ACL rupture between 2001 and 2004 were randomized to reconstruction with either a BPTB graft or a hamstring tendon graft. Patients were operated on at 4 major hospitals. The 18-year follow-up evaluation included anterior knee laxity measured with a KT-1000 arthrometer, defined as the primary outcome, while clinical examination (Lachman and pivot-shift tests), isokinetic testing of muscle strength, patient-reported outcome measures, and an assessment of radiographic osteoarthritis using the Kellgren-Lawrence classification were defined as secondary outcomes. Results: A total of 96 patients (84%, 47 BPTB and 49 hamstring grafts) were available for follow-up, 71 of these for clinical examination. Seven of 96 patients were excluded for ACL revision (n = 5) or knee replacement (n = 2) surgery. In total, 25 patients (10 BPTB and 15 hamstring grafts) had undergone additional surgery other than ACL revision or total knee arthroplasty. There were no significant differences between the groups in terms of anterior laxity test with KT-1000 arthrometer (primary outcome). In secondary outcomes, no significant differences between groups were reported regarding clinical examination, patient-reported outcome scores, or radiographic osteoarthritis (Kellgren-Lawrence grade 2-4 for patellofemoral joint [18 hamstring and 14 BPTB] or tibiofemoral joint [20 hamstring and 19 BPTB]), while isokinetic testing revealed that the hamstring group had a 10.7% reduction in mean peak flexion torque compared with the BPTB group at 60 deg/s (df = 59; P = .011). At 60 deg/s the mean total flexion work in the hamstring group was reduced by 17.2% compared with the BPTB group (df = 59; P = .002). Conclusion: The flexion strength in the hamstring group was significantly reduced in the operated knee after 18 years. There were no significant differences between the groups regarding subjective outcomes, patient-reported outcomes, range of motion, clinical and instrumented knee laxity, and the development of osteoarthritis. Registration: NCT05876013 (ClinicalTrials.gov identifier).

LEUKOCYTE ESTERASE IN THE DIAGNOSIS OF PERIPROSTHETIC JOINT INFECTION: A COMPREHENSIVE ANALYSIS

No single test has demonstrated absolute accuracy in the diagnosis of periprosthetic joint infection (PJI). Leukocyte esterase (LE) is a synovial marker that has proven utility in the diagnosis of PJI. The purpose of this prospective study was to (1) identify the optimal cutoff for the use of LE in the diagnosis of PJI and (2) determine whether performance of the LE strip test varied by infecting organism.This prospective study enrolled 1,015 patients undergoing hip or knee revision arthroplasty at a single institution from 2009 to September 2021. PJI was defined using a modified version of 2018 International Consensus Meeting (ICM) criteria that excluded LE when calculating the ICM score. Receiver operating characteristic curves were used to assess the utility of the LE strip test in the diagnosis of PJI.973 patients were included in the analyses. 246 (25.4%) were classified as ICM-positive and 727 (74.6%) were classified as ICM-negative. An LE cutoff of “1+” (AUC 0.819, sensitivity 73.2%, specificity 90.6%) had superior accuracy to an LE cutoff of “2+” (AUC 0.713, sensitivity 43.9%, specificity 98.8%) in the overall diagnosis of PJI (p&lt;0.001). When stratifying by organism type, an LE cutoff of “1+” had the best diagnostic utility for PJI caused by methicillin resistant Staphylococcus aureus (AUC 0.888, sensitivity 87.0%, n=23) followed by Streptococcus spp. (AUC 0.882, sensitivity 85.7%, n=28), coagulase negative Staphylococci (AUC 0.836, sensitivity 76.6%, n=47), methicillin sensitive Staphylococcus aureus (AUC 0.806, sensitivity 70.6%, n=34), culture negative (AUC 0.793, sensitivity 67.9%, n=56), and gram negative rods (AUC 0.763, sensitivity 61.9%, n=21).To our knowledge, this is the largest study evaluating the utility of the LE strip test in the diagnosis of PJI. Based on our findings, it appears that a “1+” cutoff has higher diagnostic utility than a cutoff of “2+”.

Prevalence, risk factors, microbiological results and clinical outcome in unexpected positive intraoperative cultures in unclear and presumed aseptic hip and knee revision arthroplasties – A ten-year retrospective analysis with a minimum follow up of 2 years

BackgroundThe aim of this study was to assess the prevalence, microbiological spectrum, risk factors, and clinical outcomes of unexpected-positive-intraoperative-cultures (UPIC) in presumed aseptic and unclear revision-total-hip-/knee-arthroplasties (rTHA and rTKA) compared to culture-negative (CN) revisions. MethodsThis study reviewed all International-consensus-meeting-2018 (ICM 2018) negative or inconclusive rTHA (n = 751) and rTKA (n = 679) performed at our institution from 2011 to 2020 with a minimum follow-up of two years. A Kaplan-Meier-analysis was performed to determine the septic and aseptic-free implant survival in cases with UPIC's and matched culture-negative cases. Patient demographics, risk factors, microbiological spectrum and clinical outcomes were evaluated. ResultsThere were significantly more UPIC cases in rTHA 196/751 (26.1 %) compared to rTKA 113/679 (16.6 %); (p < 0.001). UPICs in rTKA and rTHA have a lower septic and aseptic implant-free-survival compared to CN revisions. Patients with a history of nickel allergy have a higher risk of an UPIC in rTHA and rTKA (p < 0.001). Septic re-revisions after UPIC had a significantly (H: p = 0.004; K: p = 0.030) shorter time period to the primary/previous surgery (H: 84 (IQR:41–797); K: 115 (IQR:55–446)) compared to patients with aseptic re-revisions after UPIC (H:1248 (IQR:178-3534); K: 827 (IQR:361-1183)). ConclusionUPICs have a higher rate of septic and aseptic failure than CN outcomes. UPICs are twice as common in rTHA compared to rTKA. Preoperative PJI workup reduces the UPIC rate. Nickel allergy is a risk factor for UPIC. Early revisions with UPICs after primary THA or TKA have a higher risk of septic failure. The translational potential of this articleThis article provides new information on revision rates for UPIC and potential risk factors for UPIC and its treatment failure.

A comparison between 3D printed models and standard 2D planning in the use of metal block augments in revision knee arthroplasty.

The study focused on the ability to predict the need and size of femoral and tibial augmentation using standard two-dimensional (2D) templates and models created with three-dimensional (3D) printing in surgical planning. This observational cohort study included 28 consecutive patients (22 females, 6 males; mean age: 71±7.3 years; range, 54 to 82 years) with periprosthetic joint infection recruited between March 2021 and September 2023 undergoing revision total knee arthroplasty revision (TKA). Standard planning was made using calibrated X-ray images. The 3D planning started with computed tomography scans to generate a 3D template of the distal femur and proximal tibia. The model was exported to a 3D printer to produce a patient-specific phantom. The surgery was then simulated on the 3D phantom using revision knee arthroplasty instrumentation to evaluate the appropriate augmentation to use until a correct alignment was obtained. Three-dimensional planning predicted the need for femoral and tibial augments in 22 (78.6%) cases at both the tibial and femoral components, while 2D planning correctly predicted the need for augmentation in 17 (60.7%) for the tibial side and 18 (64.3%) for the femoral side. The Cohen's kappa demonstrated a significant agreement between the 3D planning for the femoral metal block and the intraoperative requirement (kappa=0.553), whereas 2D planning showed only nonsignificant poor agreement (kappa=0.083). In contrast, the agreement between 2D or 3D preoperative planning for tibial augment and the intraoperative requirement was nonsignificant (kappa=0.130 and kappa=0.158, respectively). On the femoral side, 2D planning showed only a fair nonsignificant correlation (r=0.35, p=0.069), whereas 3D planning exhibited substantial agreement with the actual thickness of the implanted augment (r=0.65, p<0.001). On the tibial side, 3D and 2D planning showed substantial agreement with the actual size of implanted augments (3D planning, r=0.73, p<0.001; 2D planning, r=0.69, p<0.001). Prediction based on 3D computed tomography segmentation showed significant agreement with the intraoperative need for augmentations in revision TKA. The results suggest that planning with 3D printed models represents a stronger aid in this kind of surgery rather than standard 2D planning, providing greater accuracy in the prediction of the required augmentation in revision TKA.

Unexpected positive cultures in revision total knee arthroplasty after unicompartmental knee arthroplasty.

Unexpected positive cultures are defined as a single positive culture in intraoperative samples taken during revision surgery after prosthetic joint infection was preoperatively ruled out. This study aims to determine the prevalence of unexpected positive cultures (UPC) in revision total knee arthroplasty (TKA) after unicompartmental knee arthroplasty (UKA). As a secondary objective, this study aims to compare the re-intervention rate in this specific group, between UPC and non-UPC patients. The hypothesis is that the UPC prevalence in patients who undergo a revision TKA after UKA is not higher than in other TKA revision cases and this does not increase the risk of re-intervention. This is a retrospective study where all patients who underwent a UKA revision from January 2016 to February 2023 in a high-volume arthroplasty centre, were analyzed. Unexpected positive culture prevalence in this group of patients was obtained. During the included period, 270 UKA revision surgeries were performed. Eight cases had at least two positive cultures and were therefore excluded. The final analysis included 262 patients. Of these, 8 (3.05%) patients presented UPCs and the isolated microorganisms were low-virulence organisms. None of the UPC patients received any treatment. No statistical differences were found between UPC and non-UPC groups in the analyzed variables. The prevalence of unexpected positive cultures in patients following revision of unicompartmental knee arthroplasty is lower than in patients who undergo a revision of total knee arthroplasty. In UKA patients a UPC does not seem to increase the risk of a re-intervention, so it can be safely ignored if ICM criteria are not met.

Medicaid Reimbursement for Total Hip and Knee Arthroplasty: A State-by-State Analysis Compared With Medicare

BackgroundMedicare (MCR) reimbursement for arthroplasty procedures has been declining, but little has been reported on Medicaid (MCD) reimbursement. We sought to determine MCD reimbursement rates using state MCD data for nine arthroplasty procedure codes and compare them to MCR rates. MethodsThe Centers for Medicare & Medicaid Services physician fee schedule was used to collect MCR reimbursement rates, and state MCD fee schedules were accessed to collect MCD rates for nine procedures encompassing primary and revision hip and knee arthroplasty surgery. State MCR and MCD rates were compared to determine the mean dollar difference and dollar difference per relative value unit. A cost of living adjustment was performed using the Medicare Wage Index for each state. Coefficients of variation were calculated for each state to determine overall variability between the two systems. ResultsThe mean reimbursement rates for MCD were lower for eight of the nine codes used in the study. Medicaid reimbursed physicians an average of 11.3% less overall and 23.1% less when adjusted for cost of living. The amount of variability in the MCR rates was low with a consistent coefficient of variation of 0.06, but was higher in the MCD rates with a range of 0.26 to 0.29 in the unadjusted rates and 0.34 to 0.37 in the adjusted rates. There was a mean $6.73 decreased reimbursement per relative value unit for MCD procedures. ConclusionsFor the most common arthroplasty procedures, MCD reimbursed physicians less than MCR on average. MCD also demonstrated increased variability when compared to MCR rates between states.

Altered dynamic joint space in the lateral condyle compartment following medial unicompartmental knee arthroplasty

PurposeThe progression of osteoarthritis in lateral compartment has been identified as a primary complication in medial unicompartmental knee arthroplasty (UKA) revisions, irrespective of whether employing fixed bearing (FB) or mobile bearing (MB) designs. Compared to the previous contact point analyses, the tibiofemoral contacts during knee movements are comprehended by a more comprehensive understanding of joint spaces. This study aims to dynamically map the joint spaces in the lateral compartment during the single-leg lunge following FB and MB UKA procedures, and compare them with the respective contralateral native knees. It is hypothesized that the significant change in joint space for post-UKA compared to their native knees. MethodsTwelve patients with unilateral medial FB UKA and eleven patients with unilateral medial MB UKA were included and underwent computed tomography scans. The exclusion criteria included anterior cruciate ligament deficiency, postoperative knee pain, any postoperative complications, and musculoskeletal illnesses. A dual fluoroscopic imaging system was utilized to capture the single-leg lunge, and 2D-to-3D registration facilitated the visualization of knee motion. According to the knee motions, joint spaces on tibial and femoral surfaces in the lateral compartments of native, FB, and MB UKA knees were calculated and mapped. ResultsIn comparison to the native knees, FB UKA knees exhibited significant increases in medial, lateral, central, and posterior joint spaces in the lateral compartment (p < 0.05), while MB UKA knees showed significant increases only in central and posterior joint spaces (p < 0.05). Moreover, FB UKA demonstrated greater increases in medial, central, and posterior joint spaces compared to MB UKA. Tibial varus and valgus during lunges, as well as the Oxford Knee Score (OKS) and Hip-Knee-Ankle angle (HKA), correlated with joint spaces. ConclusionsDynamic joint space analysis provided a more comprehensive insight into contact dynamics. FB UKA led to an enlargement of joint spaces, whereas MB UKA resulted in joint spaces closer to native knees. These findings contribute to understanding potential postoperative complication in UKAs.