Ultracongruent Versus Posterior-Stabilized Polyethylene: No Difference in Anterior Knee Pain but Decreased Noise Generation.

BACKGROUND: Noise generation and anterior knee pain can occur after primary total knee arthroplasty (TKA) and may affect patient satisfaction. Polyethylene design in cruciate-sacrificing implants could be a variable influencing these complications. The purpose of this study was to analyze the effect of polyethylene design on noise generation and anterior knee pain. METHODS: We prospectively reviewed a cohort of patients who underwent primary TKA between 2014 and 2022 by a single surgeon using either a posterior-stabilized (PS) or ultracongruent (UC) polyethylene of the same implant design. The primary outcomes were measured through a noise generation questionnaire and the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score. RESULTS: A total of 409 TKA procedures were included, 153 (37.4%) PS and 256 (62.6%) UC. No difference was noted in the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score between PS and UC designs (71.7 ± 26 versus 74.2 ± 23.2, P = 0.313). A higher percentage of patients in the PS cohort reported hearing (32.7% versus 22.3%, P = 0.020) or feeling noise (28.8 versus 20.3, P = 0.051) coming from their implant. No notable difference was observed in noise-related satisfaction rates. Independent risk factors of noise generation were age (OR, 0.96; P = 0.006) and PS polyethylene (OR, 1.61; P = 0.043). Noise generation was associated with decreased patient-reported outcome measure scores (P < 0.001). CONCLUSION: While there was no difference in anterior knee pain between PS and UC polyethylene designs, PS inserts exhibit higher rates of noise generation compared with UC. Noise generation had comparable satisfaction but was associated with decreased patient-reported outcome measure scores.

In Vivo Intra-Articular Antibiotic Concentrations at 24 Hours After TKA Fall Below the Minimum Inhibitory Concentration for Most Bacteria: A Randomized Study of Commercially Available Bone Cement.

BACKGROUND: The use of antibiotic-loaded bone cement (ALBC) to help reduce the risk of infection after primary total knee arthroplasty (TKA) is controversial. There is a paucity of in vivo data on the elution characteristics of ALBC. We aimed to determine whether the antibiotic concentrations of 2 commercially available ALBCs met the minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) for common infecting organisms. METHODS: Forty-five patients undergoing TKA were randomized to receive 1 of the following: bone cement without antibiotic (the negative control; n = 5), a commercially available formulation containing 1 g of tobramycin (n = 20), or a commercially available formulation containing 0.5 g of gentamicin (n = 20). Intra-articular drains were placed, and fluid was collected at 4 and 24 hours postoperatively. An automated immunoassay measuring antibiotic concentration was performed, and the results were compared against published MIC and MBEC thresholds. RESULTS: The ALBC treatment groups were predominantly of White (65%) or Black (32.5%) race and were 57.5% female and 42.4% male. The mean age (and standard deviation) was 72.6 ± 7.2 years in the gentamicin group and 67.6 ± 7.4 years in the tobramycin group. The mean antibiotic concentration in the tobramycin group was 55.1 ± 37.7 µg/mL at 4 hours and 19.5 ± 13.0 µg/mL at 24 hours, and the mean concentration in the gentamicin group was 38.4 ± 25.4 µg/mL at 4 hours and 17.7 ± 15.4 µg/mL at 24 hours. Time and antibiotic concentration had a negative linear correlation coefficient (r = -0.501). Most of the reference MIC levels were reached at 4 hours. However, at 24 hours, a considerable percentage of patients had concentrations below the MIC for many common pathogens, including Staphylococcus epidermidis (gentamicin: 65% to 100% of patients; tobramycin: 50% to 85%), methicillin-sensitive Staphylococcus aureus (gentamicin: 5% to 90%; tobramycin: 5% to 50%), methicillin-resistant S. aureus (gentamicin: 5% to 65%; tobramycin: 50%), Streptococcus species (gentamicin: 10% to 100%), and Cutibacterium acnes (gentamicin: 10% to 65%; tobramycin: 100%). The aforementioned ranges reflect variation in the MIC among different strains of each organism. Gentamicin concentrations reached MBEC threshold values at 4 hours only for the least virulent strains of S. aureus and Escherichia coli. Tobramycin concentrations did not reach the MBEC threshold for any of the bacteria at either time point. CONCLUSIONS: The elution of antibiotics from commercially available ALBC decreased rapidly following TKA, and only at 4 hours postoperatively did the mean antibiotic concentrations exceed the MIC for most of the pathogens. Use of commercially available ALBC may not provide substantial antimicrobial coverage following TKA. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Comparable Results of Single and Two-Stage Exchange for Select Periprosthetic Hip and Knee Infection.

INTRODUCTION: Although two-stage exchange has been the standard of care for periprosthetic joint infection (PJI) in the United States, single-stage exchange is emerging as an option in select patients. The purpose of this study was to compare outcomes of patients undergoing single-stage and two-stage exchange using strict surgical indications. METHODS: We reviewed a consecutive series of 196 patients with diagnosed PJI undergoing revision total knee and hip arthroplasty from 2017 to 2021. Patients were excluded if they had PJI history, plastic surgery coverage, or extensive bone loss requiring endoprosthesis. We compared the number of patients PJI-free at 1-year follow-up using MusculoSkeletal Infection Society criteria and patients requiring re-revision between the single-stage and two-stage groups. RESULTS: In total, 126 patients met inclusion criteria. Of 61 knee patients (48.4%), 22 underwent single-stage (36%) and 39 underwent two-stage (63.9%). Of 65 hip patients (51.6%), 38 underwent single-stage (58.5%) and 27 underwent two-stage (41.5%). At a mean follow-up of 1.95 ± 0.88 years, a higher rate of knee patients were classified as having treatment success in the single-stage group (77.3% versus 69.2%, P = 0.501), however with comparable septic failure rates (18.1% single-stage versus 17.9% two-stage; P = 0.982). At a mean follow-up of 1.81 ± 0.9 years, a higher rate of hip patients were classified as having treatment success in the single-stage group (94.7% versus 81.5%, P = 0.089), and more patients had septic failures in the two-stage group (18.5% versus 5.3%; P = 0.089). No differences were observed in the microorganism profile. More total complications (P = 0.021) and mortalities were found in the single-stage knee cohort than in the two-stage cohort (22.7% versus 2.6%; P = 0.011). CONCLUSION: Single-stage arthroplasty is a viable alternative to standard two-stage exchange in patients with PJI without a history of infection and with no bone or soft-tissue compromise. Additional studies with longer term follow-up are needed to evaluate its efficacy.

Porous Metal Augments Have Comparable Outcomes to Other Constructs for Severe Acetabular Bone Loss at Mid-Term Follow-up.

BACKGROUND: Acetabular reconstruction options in the setting of severe bone loss remain limited, with few comparative studies published to date. The purpose of this study was to compare the outcomes of revision total hip arthroplasty (THA) for severe bone loss using porous metal augments to cup cage and triflange prostheses. METHODS: We reviewed a consecutive series of 180 patients who had Paprosky 3A or 3B acetabular defects and underwent revision THA. Patients treated with porous augments (n = 141) were compared with those who received cup cages or triflange constructs (n = 39). Failure of the acetabular construct was defined as undergoing acetabular revision surgery or radiographic evidence of loosening. RESULTS: There was no difference in acetabular component survivorship in patients undergoing revision THA with porous augments or a cage or triflange prosthesis (92.2 versus 87.2%, P = .470) at a mean follow-up of 6.6 ± 3.4 years. Overall, survivorship free from any revision surgery was comparable between the 2 groups (78.7 versus 79.5%, P = .720). There was also no difference in dislocation (5.7 versus 10.3%, P = .309) or periprosthetic joint infection rates (7.8 versus 10.3%, P = .623). In a subgroup analysis of patients who had pelvic discontinuity (n = 47), survivorship free from any revision surgery was comparable between the 2 groups (79.5 versus 72.2%, P = .543). CONCLUSIONS: Porous metal augments in the setting of severe acetabular bone loss demonstrated excellent survivorship at intermediate-term (mean 6.6 years follow-up, even in cases of pelvic discontinuity, with comparable outcomes to cup cages and triflanges. Instability and infection remain major causes of failure in this patient population, and long-term follow-up is needed.

Serum and Synovial Markers in the Diagnosis of Periprosthetic Joint Infection of the Hip, Knee, and Shoulder: An Algorithmic Approach.

➤ No single test has demonstrated absolute accuracy for the diagnosis of periprosthetic joint infection (PJI).➤ Physicians rely on a combination of serological tests, synovial markers, and clinical findings plus clinical judgment to help to guide preoperative decision-making.➤ Several organizations have proposed criteria for the diagnosis of hip or knee PJI on which we now rely.➤ Given that shoulder arthroplasty has only recently become popular, it is possible that a shoulder-specific definition of PJI will be introduced in the coming years.➤ Although a number of serum and synovial markers have demonstrated high accuracy for the diagnosis of PJI of the hip and knee, further research is needed in order to identify markers that may be more suitable for the diagnosis of shoulder PJI and for the potential development and identification of specific serological tests as screening tools for PJI.

Prior Authorization Leads to Administrative Burden and Delays in Treatment in Primary Total Joint Arthroplasty Patients.

BACKGROUND: The prior authorization (PA) process is often criticized by physicians due to increased administrative burden and unnecessary delays in treatment. The effects of PA policies on total hip arthroplasty (THA) and total knee arthroplasty (TKA) have not been well described. The purpose of this study was to analyze the use of PA in a high-volume orthopaedic practice across 4 states. METHODS: We prospectively collected data on 28,725 primary THAs and TKAs performed at our institution between 2020 and 2023. Data collected included patient demographics, payer approval or denial, time to approval or denial, the number of initial denials, the number of peer-to-peer (P2P) or addenda, and the reasons for denial. RESULTS: Seven thousand five hundred twenty eight (56.4%) patients undergoing THA and 8,283 (54%) patients undergoing TKA required PA, with a mean time to approval of 26.3 ± 34.6 and 33.7 ± 41.5 days, respectively. Addenda were requested in 608 of 7,528 (4.6%) THA patients and 737 of 8,283 (8.9%) TKA patients. From a total of 312 (4.1%) THA patients who had an initial denial, a P2P was requested for 50 (0.7%) patients, and only 27 (0.4%) were upheld after the PA process. From a total of 509 (6.1%) TKA patients who had an initial denial, a P2P was requested for 55 (0.7%) patients, and only 26 (0.3%) were upheld after the PA process. The mean time to denial in the THA group was 64.7 ± 83.5, and the most common reasons for denial were poor clinical documentation (25.9%) and lack of coverage (25.9%). The mean time to denial in the TKA group was 63.4 ± 103.9 days, and the most common reason for denial was not specified by the payer (46.1%). CONCLUSIONS: The use of PA to approve elective THA and TKA led to increased surgical waiting times and a high administrative burden for surgeons and healthcare staff.

Finding the Optimal Screening Test for Periprosthetic Joint Infection: A Prospective Study.

BACKGROUND: No single test has demonstrated absolute accuracy in the diagnosis of periprosthetic joint infection (PJI). Serological markers are often used as screening tools to avoid unnecessary joint aspiration in cases with a low probability of infection. This study aimed to determine the utility of standard-of-care serological tests as a screening tool for PJI in patients undergoing revision arthroplasty. METHODS: This prospective study enrolled 502 patients undergoing revision hip or knee arthroplasty between May 2017 and August 2021. A PJI was defined using a modified definition of the 2018 International Consensus Meeting criteria. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. There were 82 patients undergoing reimplantation who were excluded. Additionally, 8 patients who had an inconclusive International Consensus Meeting score were also excluded. Of the 412 included patients, 317 (76.9%) underwent revision for aseptic failure, and 95 (23.1%) had PJI. Receiver operating characteristic curves were used to assess the diagnostic utility of each serological test. A pairwise comparison with Bonferroni correction was performed to determine whether the differences in areas under the curve (AUCs) between the tests were significant. Additional analyses were performed to find the threshold for each test that offered 100% sensitivity, allowing it to be the optimal screening test. RESULTS: All 4 serological markers, D-dimer (AUC 0.860, sensitivity 81.3%, specificity 81.7%), CRP (AUC 0.862, sensitivity 90.4%, specificity 70.0%), ESR (AUC 0.833, sensitivity 73.9%, specificity 85.2%), and fibrinogen (AUC 0.798, sensitivity 74.7%, specificity 75.4%), demonstrated comparable accuracy for the diagnosis of PJI (all P > .05). When maximizing sensitivity to 100%, D-dimer demonstrated the highest specificity (AUC 0.860, specificity 40.2%), outperforming ESR (AUC 0.833, specificity 3.3%), fibrinogen (AUC 0.798, specificity 2.3%), and CRP (AUC 0.862, specificity 0%). A plasma D-dimer level of ≥ 244 ng/mL was identified as the optimal cutoff for use as a screening test. CONCLUSIONS: Although plasma D-dimer demonstrated similar diagnostic accuracy as CRP, ESR, and fibrinogen, it outperformed all 3 aforementioned serological markers when used as a screening test for PJI. LEVEL OF EVIDENCE: Level II.

Outcomes of Metaphyseal Cones and Stem Fixation Following Rotating Hinge in Complex Primary and Revision Total Knee Arthroplasty.

BACKGROUND: Although hinged prostheses have been used successfully in complex revision total knee arthroplasty (TKA), concerns exist regarding early failure due to aseptic loosening and other mechanical complications. The use of metaphyseal cones and hybrid cement fixation have been studied in unlinked constrained primary or revision TKA, but their impact on the survivorship of hinged prostheses has yet to be investigated. METHODS: We identified a consecutive series of 164 hinged prostheses and collected data on demographics, indications, complications, and re-revisions in patients who had fully cemented versus hybrid stems, with and without metaphyseal cones. A multivariate analysis was performed to identify independent variables associated with re-revision as the primary end point. RESULTS: In total, 84 patients (51.2%) had fully cemented stems, and 80 patients (48.8%) had hybrid stems. Cones were used in 73 patients (44.5%). At a mean follow-up of 3.4 ± 2.2 years, 42 patients underwent re-revision (25.8%), most commonly for infection (12.2%), followed by loosening (6.7%) and periprosthetic fracture (3.7%). Patients who had fully cemented stems had lower re-revision rates than hybrid fixation constructs (19 versus 26%, P = .043). Using multivariable regression, a construct with hybrid fixation with cones (odds ratio = 2.39; P = .037) was an independent risk factor for failure. Utilization of cones alone did not have an effect on re-revision rates at 3.4-year follow-up. CONCLUSIONS: While we found no difference with the use of cones, patients undergoing revision TKA with a hinge prosthesis and fully cemented stems had better overall survivorship than hybrid stems.

Determinants of High Facility Costs in Total Joint Arthroplasty Patients: A Time-driven Activity-based Costing Analysis.

INTRODUCTION: Although several studies identify risk factors for high-cost patients in an episode of care for total hip (THA) and knee arthroplasty (TKA), few have looked at cost outliers from a facility perspective. The purpose of this study was to use time-driven activity-based costing (TDABC) to identify characteristics of high-cost patients. METHODS: We reviewed a consecutive series of primary THA and TKA patients by 22 different surgeons at two hospitals between 2015 and 2020. Facility costs were calculated using a TDABC algorithm for their entire hospital stay. Patients in the top decile of costs were considered to be high-cost patients. Multivariate regression was done to identify independent patient factors that predicted high costs. RESULTS: Of the 8,647 patients we identified, 60.5% underwent THA and 39.5% underwent TKA. Implant purchase price accounted for 49.5% of total inpatient costs (mean $2,880), followed by intraoperative (15.9%, mean $925) and postoperative personnel costs (16.8%, mean $980). Implant price demonstrated the highest variation between high-cost and low-cost groups (4.4 times). Patient-related factors associated with high costs were female sex (OR = 1.332), Hispanic ethnicity (OR = 1.409), American Society of Anesthesiology score (OR = 1.658), need for transfusion (OR = 2.008), and lower preoperative HOOS/KOOS Jr (OR = 1.009). CONCLUSION: This study identifies several variables for patients at risk to have high facility costs after primary THA and TKA. From the hospital's perspective, efforts to reduce implant purchase prices may translate into substantial cost savings. At the patient level, multidisciplinary initiatives to optimize medical comorbidities, decrease transfusion risk, and control medication expenses in high-risk patients may narrow the existing variation in costs.

Plasma D-Dimer Is a Promising Marker to Guide Timing of Reimplantation: A Prospective Cohort Study.

BACKGROUND: Two-stage exchange arthroplasty remains the preferred surgical treatment for chronic periprosthetic joint infection. Currently, there is no single reliable marker to determine the optimal timing for reimplantation. The purpose of this prospective study was to assess the diagnostic utility of plasma D-dimer and other serological markers in predicting successful control of infection following reimplantation. METHODS: This study enrolled 136 patients undergoing reimplantation arthroplasty between November 2016 and December 2020. Strict inclusion criteria were applied including the need for a two-week "antibiotic holiday" prior to reimplantation. A total of 114 patients were included in the final analysis. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. Treatment success was defined using the Musculoskeletal Infection Society Outcome-Reporting Tool. Receiver operating characteristic curves were used to assess the prognostic accuracy of each biomarker in predicting failure following reimplantation at a minimum 1-year follow-up. RESULTS: Treatment failure occurred in 33 patients (28.9%) at a mean follow-up of 3.2 years (range, 1.0 to 5.7). Median plasma D-dimer was significantly higher in the treatment failure group (1,604 versus 631 ng/mL, P < .001), whereas median CRP, ESR, and fibrinogen were not significantly different between the success and failure groups. Plasma D-dimer demonstrated the best diagnostic utility (area under the curve [AUC] 0.724, sensitivity 51.5%, specificity 92.6%), outperforming ESR (AUC 0.565, sensitivity 93.3%, specificity 22.5%), CRP (AUC 0.541, sensitivity 87.5%, specificity 26.3%), and fibrinogen (AUC 0.485, sensitivity 30.4%, specificity 80.0%). Plasma D-dimer level of ≥1,604 ng/mL was identified as the optimal cutoff that predicted failure following reimplantation. CONCLUSION: Plasma D-dimer was superior to serum ESR, CRP, and fibrinogen in predicting failure after the second stage of a two-stage exchange arthroplasty for periprosthetic joint infection. Based on the findings of this prospective study, plasma D-dimer may be a promising marker in assessing the control of infection in patients undergoing reimplantation surgery. LEVEL OF EVIDENCE: Level II.