Similar Efficacy and Lower Cost Associated With Ceftazidime Compared to Tobramycin Coupled With Vancomycin in Antibiotic Spacers in the Treatment of Periprosthetic Joint Infection.

BACKGROUND: Vancomycin and tobramycin have traditionally been used in antibiotic spacers. In 2020, our institution replaced tobramycin with ceftazidime. We hypothesized that the use of ceftazidime/vancomycin (CV) in antibiotic spacers would not lead to an increase in treatment failure compared to tobramycin/vancomycin (TV). METHODS: From 2014 to 2022, we identified 243 patients who underwent a stage I revision for periprosthetic joint infection. The primary outcome was a recurrent infection requiring antibiotic spacer exchange. We were adequately powered to detect a 10% difference in recurrent infection. Patients who had a prior failed stage I or two-stage revision for infection, acute kidney injury prior to surgery, or end-stage renal disease were excluded. Given no other changes to our spacer constructs, we estimated cost differences attributable to the antibiotic change. Chi-square and t-tests were used to compare the two groups. Multivariable logistic regressions were utilized for the outcomes. RESULTS: The combination of TV was used in 127 patients; CV was used in 116 patients. Within one year of stage I, 9.8% of the TV group had a recurrence of infection versus 7.8% of the CV group (P = .60). By final follow-up, results were similar (12.6 versus 8.6%, respectively, P = .32). Adjusting for potential risk factors did not alter the results. Cost savings for ceftazidime versus tobramycin are estimated to be $68,550 per one hundred patients treated. CONCLUSIONS: Replacing tobramycin with ceftazidime in antibiotic spacers yielded similar periprosthetic joint infection eradication success at a lower cost. While larger studies are warranted to confirm these efficacy and cost-saving results, our data justifies the continued investigation and use of ceftazidime as an alternative to tobramycin in antibiotic spacers.

Decreased Patellar Fractures and Subluxation With Patellar Component Replacement at Stage-One Spacer.

BACKGROUND: Periprosthetic joint infection is a devastating complication of total knee arthroplasty and is often treated with 2-stage revision. We retrospectively assessed whether replacing the patellar component with articulating stage-one spacers was associated with improved outcomes compared to spacers without patellar component replacement. METHODS: A total of 139 patients from a single academic institution were identified who underwent an articulating stage-one revision total knee arthroplasty and had at least 1-year follow-up. Of the 139 patients, 91 underwent patellar component removal without replacement, while 48 had a patellar component replaced at stage-one revision. Patellar fracture and reinfection at any point after stage-one were recorded. Knee range of motion (ROM), patellar thickness, lateral tilt, and lateral displacement were measured at 6-weeks post stage-one. Chi-square, Fisher's exact, and t-tests were utilized for comparisons. There were no significant demographic differences between groups. RESULTS: Patellar component replacement at stage-one revision was associated with fewer patellar fractures (2.1 versus 12.1%, P = .046), less lateral patellar displacement (1.7 versus 16.0 mm, P < .01), and improved pre to postoperative knee ROM 6 weeks after stage-one (+5.9 versus -11.4°, P = .03). There was no difference in reinfections after stage-2 revision for the replaced or unreplaced patellar groups (15.4 versus 15%, P = 1.000). While the mean time between stage-one and stage-2 was not different (5.2 versus 4.5 months, P = .50), at one-year follow-up, significantly more patients in the patellar component replacement group were satisfied and refused stage-2 revision (45.8 versus 3.3%, P < .001). CONCLUSIONS: Replacing the patellar component at stage-one revision is associated with a decreased rate of patellar fracture and lateral patellar subluxation, improved ROM, and possible increased patient satisfaction, as reflected by nearly half of these patients electing to keep their spacer. There was no difference in reinfection rates between the cohorts.

Delayed Diagnosis of Mycobacteriumbovisbacillus Calmette-Guérin Periprosthetic Joint Infection Following Total Knee Arthroplasty.

Periprosthetic joint infection (PJI) can present challenges in diagnosis and treatment, particularly in the setting of atypical causative organisms such as fungi and mycobacteria. Herein, we present a case and provide a review of the diagnosis and treatment of an unusual PJI caused by bacillus Calmette-Guérin, administered during the treatment of bladder cancer 3 years prior to total knee arthroplasty and subsequent PJI. Although the patient's history of bladder cancer was known, neither his Bacillus Calmette-Guérin treatment nor its potential for distant site spread that could lead to PJI were appreciated, leading to a prolonged diagnostic evaluation and treatment course.

Risk Factors for Return to the Emergency Department and Readmission After Same-Day Discharge Total Joint Arthroplasty.

BACKGROUND: Same-day discharge (SDD) after total joint arthroplasty (TJA) is safe and cost effective. However, benefits may be offset by the potential cost of emergency department (ED) visits and readmissions. We identified risk factors for return to the ED and readmission in patients who underwent SDD and inpatient (IP) stays after TJA. METHODS: We performed a retrospective review of patients who underwent primary TJA at an academic institution over the course of one year. There were 1,708 consecutive TJAs (721 THA [total hip arthroplasty] and 987 TKA [total knee arthroplasty]) included. A SDD occurred after 1,199 (70%) TJAs, 523 THAs, and 676 TKAs. We compared the demographics and comorbidities of patients who have SDD or IP who stayed following TJA. We documented rates of return to the ED or readmission within 90 days of surgery. Cohorts were compared using the Student's t-test or Chi-square test. Significant findings were those with P value < .05. RESULTS: The SDD cohort had a significantly higher rate of young, non-White men who had a lower body mass index and fewer comorbidities than the IP cohort. Rates of return to ED and readmission were similar between SDD and IP cohorts after TJA and similar between THA and TKA. Factors that significantly influenced return to ED included a higher American Society of Anaesthesiologists score (SDD, IP), a higher Charlson Comorbidity Index score (SDD, IP), a lower body mass index (IP), and a psychological diagnosis (SDD, IP). Factors that significantly influenced readmission rates included a higher American Society of Anaesthesiologists score (SDD), older age (SDD), and psychological diagnosis (SDD, IP). CONCLUSIONS: Patients who discharged the same day after primary TJA have similar rates of return to the ED and readmission as those admitted as an IP. Patients who had a psychological diagnosis, and particularly a diagnosis of depression, are at higher risk for return to the ED and readmission after primary TJA, regardless of discharge the same-day or IP admission. Improved measures that attempt to further treat and optimize this patient population could reduce unnecessary postoperative ED visits.

Outpatient Total Joint Arthroplasty at a High-Volume Academic Center: An Analysis of Failure to Launch.

BACKGROUND: Unanticipated failure to discharge home (failure to launch, FTL) following scheduled same-day discharge (SDD) total joint arthroplasty (TJA) is problematic for the surgical facility with respect to staffing, care coordination, and reimbursement concerns. The aim of this study was to review rates, etiologies, and contributing factors for FTL in SDD TJA at an inpatient academic medical center. METHODS: All patients who underwent primary TJA between February 2021 and February 2023 were retrospectively reviewed. Of those scheduled for SDD, risk factors for FTL were compared with successful SDD. Readmission and emergency department (ED) visits were compared with historical cohorts. There were 3,093 consecutive primary joint arthroplasties performed, of which 2,411 (78%) were scheduled for SDD. RESULTS: Overall, SDD was successful in 94.2% (n = 2,272) of patients who had an FTL rate of 5.8%. Specifically, SDD was successful in 91.4% with total hip arthroplasty, 96.0% with total knee arthroplasty, and 98.6% with unicompartmental knee arthroplasty. Factors that significantly increased the risk of FTL included general anesthesia versus spinal anesthesia (P < .0001), later surgery start time (P < .0001), longer surgical time (P = .0043), higher estimated blood loss (P < .0001), women (P = .0102), younger age (P = .0079), and lower preoperative mental health patient-reported outcomes scores (P = .0039). Readmission and ED visit rates were not higher in the SDD group when compared to historical controls (P = .6830). CONCLUSIONS: With a comprehensive multidisciplinary approach dedicated to improving SDDs at an academic medical center, we have seen successful SDD in nearly 80% of primary TJA, with an FTL rate of 5.8%, and no increased risk of readmission or ED visits. Without adding many personnel, hospital recovery units, or other resources, simple interventions to help decrease FTL have included enhanced preoperative education and expectation settings, improved perioperative communications, reallocating personnel from the inpatient to the outpatient setting, the use of short-acting spinal anesthetics, and earlier scheduled surgery times.

The Empty Ischial Fossa Sign: A Visual Representation of Relative Inadequate Anteversion in the Posteriorly Tilted Pelvis.

Background: Instability is a known complication following total hip arthroplasty (THA) and is influenced by spinopelvic alignment. Radiographic markers have been investigated to optimize the acetabular cup position. This study evaluated if the empty ischial fossa (EIF) sign and the position of the trans-teardrop line were predictive of postoperative instability. Methods: All patients who underwent THA from 2011 to 2018 at a single institution were retrospectively reviewed. Pelvic tilt was measured using a trans-teardrop line compared to the superior aspect of the pubic symphysis on standing anteroposterior pelvis radiographs. Postoperative dislocations were identified through chart review and radiographic review. The EIF sign was determined by the presence of uncovered bone below the posterior inferior edge of the acetabular component at the level of the native ischium and posterior wall on standing postoperative anteroposterior radiographs. Results: One thousand seven hundred fifty patients (952 anterior approach and 798 posterior approach) were included. The EIF sign was present in 458 patients (26.2%) and associated with an increased dislocation rate (3.9% vs 0.9%, P < .0001). Patients with spondylosis/instrumented fusion, and positive EIF sign had a dislocation risk of 5.1% vs 1.3% (P = .001). A postoperative outlet pelvis was not significant for increased dislocation risk (odds ratio 2.16, P = .058). Patients with combined spondylosis/fusion, posterior approach, outlet pelvis, and EIF sign had a dislocation rate of 14.5%. Conclusions: The EIF sign was an independent risk factor for postoperative instability and may represent failure to account for pelvic tilt. Avoidance of the EIF sign during cup positioning may help reduce dislocations following THA.

Impact of Demographic Variables on Recovery After Total Hip Arthroplasty.

BACKGROUND: Several patient factors affect recovery after total hip arthroplasty (THA). However, the impact of these variables on patient-reported outcome measure recovery curves following THA has not been defined. Our goal was to quantify the influence of multiple variables on recovery after primary THA. METHODS: There were 1,724 patients in a multicenter study included. Variables included sex, race/ethnicity, anxiety/depression, body mass index, tobacco, and preoperative opioid use. The Hip disability and Osteoarthritis Score for Joint Replacement (HOOS JR) was recorded at multiple time points. Recovery curves were created using longitudinal estimating equations. RESULTS: Patients who were women, obese, or smokers demonstrated lower HOOS JR scores at all time points. Preoperative opioid use was also correlated with lower HOOS JR scores, but this difference diminished after 6 months. Black patients demonstrated lower HOOS JR scores compared to Caucasians, and this relative difference increased out to 1-year postoperatively (P = .018). Hispanics also had lower HOOS JR scores, but scores recovered at similar rates compared to non-Hispanics. Patients who had only anxiety or depression had similar HOOS JR scores compared to patients who did not have anxiety or depression. However, patients who had both anxiety and depression had lower HOOS JR scores compared to patients who had neither (P = .049), and this relative difference became greater at 1-year postoperatively (P = .002). CONCLUSIONS: Several factors including race/ethnicity, opioid use, and mental health influence recovery trajectory following THA. This information helps provide more individualized counseling about expectations after THA and focus targeted interventions to improve outcomes in at-risk groups.

Metallosis and Corrosion Associated With Revision Total Knee Arthroplasties With Metaphyseal Sleeves.

Metallosis and corrosion have been associated with metal-on-metal and modular total hip arthroplasty but are rarely described in the setting of primary or revision total knee arthroplasty (TKA). In this series, we report on cases of metallosis due to mechanically assisted crevice corrosion at modular junctions of machined trunnion-bore tapers in a revision TKA system with metaphyseal sleeves. The unique design of metal modular junctions used in sleeve-based revision TKA, along with potential patient and surgical factors, may predispose these designs to fretting, corrosion, and adverse reaction to metal debris. We now consider metallosis and corrosion in the workup of painful or failed revision TKAs with sleeves. Future studies that investigate the incidence of this phenomenon may be warranted.

A Novel Method to Calculate Functional Pelvic Tilt Using a Standing Anteroposterior Pelvis Radiograph.

Background: Functional patient-specific acetabular component positioning is important in total hip arthroplasty. We preoperatively evaluate the pelvic tilt (PT) on standing anteroposterior (AP) pelvis radiographs using a novel measurement and then recreate this intraoperatively using imaging. The purpose of this study was to determine if there is a linear correlation between this novel measurement and the actual PT. Methods: A retrospective study of 200 patients was performed, measuring PT on standing lateral radiographs as the angle between the anterior superior iliac spines and the pubic symphysis. On the AP pelvis radiographs, the trans-teardrop (TT) line was drawn between the teardrops. The vertical distance between the TT line and the top of the pubic symphysis (TTPS) was then measured. A ratio was made between the lengths of both lines to account for the overall size of the pelvis (TTPS/TT). Linear regression analysis was then performed between PT and TTPS/TT. Results: There was a strong linear correlation between the TTPS/TT ratio on AP pelvis radiographs and PT on lateral radiographs (r = 0.785, r2 = 0.616, P < .001). On subanalysis of the female cohort, the correlation became even stronger (r = 0.864, r2 = 0.747, P < .001). Using regression analysis, a linear equation was created (PT = 97.32 [TTPS/TT] - 5.51), to calculate the PT using the TTPS/TT ratio. Conclusions: There is a strong linear correlation between the TTPS/TT ratio and PT. Using this information, a surgeon can reliably use the distance between the TT line and the superior pubic symphysis on an AP radiograph to recreate the patient's functional PT intraoperatively, allowing for a more accurate patient-specific placement of the acetabular component.

Association of Acute Kidney Injury With Antibiotic Loaded Cement Used for Treatment of Periprosthetic Joint Infection.

BACKGROUND: Antibiotic-loaded bone cement (ALBC) is commonly used in the treatment of periprosthetic joint infections (PJIs) to increase the local concentration of antibiotic at the site of infection. Use of ALBC has been associated with rare instances of acute kidney injury (AKI) despite low systemic absorption of the nephrotoxic antibiotics; however, the incidence of AKI is unknown. The purpose of this study was to determine the incidence of and risk factors for AKI associated with ALBC. METHODS: This single-site, retrospective cohort study compared 162 PJI patients who underwent Stage 1 revision to a spacer with ALBC to 115 PJI patients who underwent debridement, antibiotics, and implant retention (DAIR) without the use of ALBC. Both groups received similar systemic antibiotics postoperatively. Descriptive statistics and multivariable logistic regressions were used to analyze risk factors for AKI. RESULTS: There was no statistically significant difference in the rate of AKI: 29 patients (17.9%) in the ALBC group and 17 (14.7%) in DAIR group developed AKI (odds ratio 1.43; 95% CI 0.70 to 2.93). There was a trend toward increased severity of AKI in the ALBC group. Chronic kidney disease, systemic vancomycin, and diuretic use were independent factors associated with the risk of AKI. CONCLUSION: An AKI occurred in 17% of PJI patients receiving either a spacer with ALBC or a DAIR. The use of ALBC was not associated with a significant increased risk of AKI. However, the use of systemic vancomycin and diuretic use were independent predictors of AKI in this patient population.

The Microbiome of Osteoarthritic Hip and Knee Joints: A Prospective Multicenter Investigation.

BACKGROUND: Recent advances in high-throughput DNA sequencing technologies have made it possible to characterize the microbial profile in anatomical sites previously assumed to be sterile. We used this approach to explore the microbial composition within joints of osteoarthritic patients. METHODS: This prospective multicenter study recruited 113 patients undergoing hip or knee arthroplasty between 2017 and 2019. Demographics and prior intra-articular injections were noted. Matched synovial fluid, tissue, and swab specimens were obtained and shipped to a centralized laboratory for testing. Following DNA extraction, microbial 16S-rRNA sequencing was performed. RESULTS: Comparisons of paired specimens indicated that each was a comparable measure for microbiological sampling of the joint. Swab specimens were modestly different in bacterial composition from synovial fluid and tissue. The 5 most abundant genera were Escherichia, Cutibacterium, Staphylococcus, Acinetobacter, and Pseudomonas. Although sample size varied, the hospital of origin explained a significant portion (18.5%) of the variance in the microbial composition of the joint, and corticosteroid injection within 6 months before arthroplasty was associated with elevated abundance of several lineages. CONCLUSIONS: The findings revealed that prior intra-articular injection and the operative hospital environment may influence the microbial composition of the joint. Furthermore, the most common species observed in this study were not among the most common in previous skin microbiome studies, suggesting that the microbial profiles detected are not likely explained solely by skin contamination. Further research is needed to determine the relationship between the hospital and a "closed" microbiome environment. These findings contribute to establishing the baseline microbial signal and identifying contributing variables in the osteoarthritic joint, which will be valuable as a comparator in the contexts of infection and long-term arthroplasty success. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Recovery Curves for Patient Reported Outcomes and Physical Function After Total Hip Arthroplasty.

BACKGROUND: Patient-reported outcome measures (PROMs) are frequently used for evaluating patient satisfaction and function following total hip arthroplasty (THA). Functional measures along with chronologic modeling may help set expectations perioperatively. Our goal was to define the trajectory of recovery and function in the first year following THA. METHODS: Prospective data from 1,898 patients in a multicenter study was analyzed. The PROMs included the Hip disability and Osteoarthritis Score for Joint Replacement and EuroQol-5 dimension. Physical activity was recorded on a wearable technology. Data was collected preoperatively and at 1, 3, 6, and 12 months postoperatively. Generalized estimating equations were used to evaluate outcomes over time. RESULTS: Significant improvement occurred between preoperative and postoperative time points for all PROMs. The PROMs showed the greatest proportional recovery within the first month postoperatively, each improving by at least 1 minimal clinically important difference (MCID). Daily steps and flights of stairs took longer to reach at least 1 MCID (3 months and 1 year, respectively). Gait speed and walking asymmetry returned to baseline by 3 months, but did not reach a MCID of improvement by 1 year. CONCLUSION: Patients can be counseled that the greatest proportional improvement in PROMs is within 1 month after THA, while function surpasses preoperative baselines by 3 months, and gait quality may not improve until after 1 year. This can help set realistic expectations and target interventions toward patients deviating from the norm.

Outcomes are Compromised When Revising Patellofemoral Arthroplasties for Patellar Component Failures.

BACKGROUND: Outcomes of patellofemoral arthroplasty (PFA) to total knee arthroplasty (TKA) conversion are reported to be similar to primary cases. The purpose of this study was to determine whether the cause for conversion from PFA to TKA correlated to outcomes when compared to a matched cohort. METHODS: A retrospective chart review was performed to identify aseptic PFA to TKA conversions between 2000 and 2021. A cohort of primary TKAs was matched by patient sex, body mass index, and American Society of Anesthesiology score. Clinical outcomes, including range of motion, complication rates, and patient reported outcomes measurement information systems scores, were compared. Chi-squared, Fisher's Exact, and t-tests were performed. There were 20 PFA to TKA conversions that met inclusion criteria and were matched to 60 primary cases. RESULTS: There were 7 cases revised for arthritis progression, 5 for femoral component failure, 5 for patellar component failure, and 3 for patellar maltracking. PFA to TKA conversions for patellar failure (fracture, component loosening) had worse postoperative flexion (115 versus 127°, P = .023) and more complications of stiffness (40 versus 0%, P = .046) than primary TKAs. Conversions for failed patellar components had worse patient reported outcomes measurement information systems physical function (32 versus 45, P = .0046), physical health (42 versus 49, P = .0258), and pain scores (45 versus 24, P = .0465). No differences were found in rates of infection, manipulations under anesthesia, or reoperations. CONCLUSION: PFA to TKA conversion outcomes were similar to primary TKA, except in patients who had failed patellar components and demonstrated worse postoperative range of motion and patient-reported outcomes. Surgeons should avoid thin patellar resections and extensive lateral releases to minimize patellar failures.

Recovery Curve for Patient Reported Outcomes and Objective Physical Activity After Primary Total Knee Arthroplasty-A Multicenter Study Using Wearable Technology.

BACKGROUND: This study aimed to describe the trajectory of recovery based on patient-reported outcomes (PROs) and objective metrics of physical activity measures over the first 12 months post-total knee arthroplasty (TKA). METHODS: In total, 1,005 participants who underwent a primary unilateral TKA surgery between November 2018 and September 2021 from a multisite prospective study were analyzed. Generalized estimating equations were used to evaluate PROs and objective physical activity measures over time. RESULTS: All Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), EuroQol-5D (EQ-5D), and steps per day scores were greater than preoperative scores (P < .05). The flights of stairs per day, gait speed, and walking asymmetry all declined at 1 month (all, P < .001). However, all subsequent scores improved by 6 months (all, P < .01). The greatest clinically important differences from previous visit in KOOS JR (ß = 18.1; 95% Confidence Interval (CI) = 17.2, 19.0), EQ-5D (ß = 0.11; 95% CI = 0.10, 0.12), steps per day (ß = 1,169.3; 95% CI = 1,012.7, 1,325.9), gait speed (ß = -0.05; 95% CI = -0.06, -0.03), and walking asymmetry (ß = 0.00; 95% CI = -0.03, 0.03) were observed at 3 months. CONCLUSION: The KOOS JR, EQ-5D, and steps per day measures showed earlier improvements than other physical activity metrics, with the greatest magnitude of improvement within the first 3 months post-TKA. The greatest magnitude of improvement in walking asymmetry was not observed until 6 months, while gait speed and flights of stairs per day were not observed until 12 months. This data may further help provide expectation setting information to patients before surgery, and may aid in identifying outliers to the normal recovery curve who may benefit from targeted interventions.

Extensor Mechanism Disruption Remains a Challenging Problem.

BACKGROUND: Extensor mechanism disruption (EMD) following total knee arthroplasty (TKA) is a devastating problem commonly treated with allograft or synthetic reconstruction. Understanding of reconstruction success rates and patient recorded outcomes is lacking. METHODS: Patients who have an EMD after TKA undergoing mesh or whole-extensor allograft reconstruction between 2011 and 2019, with minimum 2-year follow-up were reviewed at two tertiary care centers. Functional failure was defined as extensor lag >30 degrees, amputation, or fusion, as well as revision extensor mechanism reconstruction (EMR). Survivorship was assessed using Kaplan-Meier curves, and factors for success were determined with logistic regressions. RESULTS: Of fifty-six EMRs (49 patients), 50.0% (28/56) were functionally successful at 3.2 years of mean follow-up (range, 0.2 to 7.4). In situ survivorship of the reconstructions at 36 months was 75.0% (42 of 58). There were 50.0% (14 of 28) of functionally failed EMRs that retained their reconstruction at last follow-up. Mean extensor lag among successes and failures was 5.4 and 71.0° (P = .01), respectively. Mean Knee Injury and Osteoarthritis Outcome Score, Joint Replacement scores were 67.1 and 48.8 among successes and failures (P = .01). There were 64.0% (16 of 25) of successes and 1 of 19 failures that obtained a Knee Injury and Osteoarthritis Outcome Score, Joint Replacement score above the minimum patient-acceptable symptom state for TKA. Survivorship and success rates were similar between reconstruction methods (P = .86; P = .76). All-cause mortality was 8.2% (4 of 49), each with EMR failure prior to death. All-cause reoperation rate was 42.9% (24 of 56), with a 14.3% (8 of 56) rate of revision EMR and 10.7% (6 of 56) rate of above-knee-amputation or modular fusion. CONCLUSIONS: This multicenter investigation of mesh or allograft EMR demonstrated modest functional success at 3.2 years. Complication and reoperation rates were high, regardless of EMR technique. Therefore, EMD after TKA remains problematic.

Trends in Total Knee Arthroplasty Cementing Technique Among Arthroplasty Surgeons-A Survey of the American Association of Hip and Knee Surgeons Members.

BACKGROUND: Aseptic loosening persists as one of the leading causes of failure following cemented primary total knee arthroplasty (TKA). Cement technique may impact implant fixation. We hypothesized that there is variability in TKA cement technique among arthroplasty surgeons. METHODS: A 28-question survey regarding variables in surgeons' preferred TKA cementation technique was distributed to 2,791 current American Association of Hip and Knee Surgeons (AAHKS) members with a response rate of 30.8% (903 respondents). Patterns of responses were analyzed by grouping respondents by their answers to certain questions including cementing technique, tibial cement location, and femoral cement location. RESULTS: A total of 73.5% reported performing at least 7 of 8 of the highest consensus techniques, including vacuum mixing (79.9%), using two bags (76.1%), tibial implant first (95.2%), single-stage cementing (96.9%), compression of the implants in extension (91.7%), and use of a tourniquet (84.3%). Medium and high viscosity cement was most commonly used (37.9 and 37.8%, respectively). Finger pressurization was most common (76.1%) compared to a gun (29.8%). There were 26.5% of respondents performing 6 or fewer of the most common majority techniques and seemed to perform other less common techniques (eg, use of a single bag of cement, trialing or closure prior to cement curing, and heating to accelerate cement curing). Cement was most commonly applied to the entire bone and implant surface on both the tibia (46.4%) and femur (47.7%), leaving much variation in the remaining cement application location responses. DISCUSSION: There appears to be variability in cemented TKA technique among arthroplasty surgeons. There were 26.5% of respondents performing less of the majority techniques and also performed other additional low-response rate techniques. Further studies that look at the impacts of variation in techniques on outcomes may be warranted. Our study demonstrates the need for defining best practices for cement technique given the substantial variability identified.

The James A. Rand Young Investigator's Award: Increased Revision Risk With Mobile Bearings in Total Knee Arthroplasty: An Analysis of the American Joint Replacement Registry.

BACKGROUND: Mobile-bearing (MB) total knee arthroplasty (TKA) may reduce wear and improve patellar tracking but may increase revision risk due to tibial component design, balance complexity, and bearing dislocation. We utilized the American Joint Replacement Registry to examine risk of revision with MB compared to fixed-bearing (FB) designs. METHODS: An analysis of primary TKA in patients over 65 years was performed with American Joint Replacement Registry data linked to Centers for Medicare and Medicaid Services data from 2012 to 2019. Analyses compared MB to FB designs with a subanalysis of implants from a single company. We identified 485,024 TKAs, with 452,199 (93.2%) FB-TKAs and 32,825 (6.8%) MB-TKAs. Cox proportional hazards regression modeling was used for all-cause revision and revision for infection, adjusting for sex, age, and competing risk of mortality. Event-free survival curves evaluated time to all-cause revision and revision for infection. RESULTS: MB-TKAs were at an increased risk for all-cause revision: hazard ratio (HR) 1.36 ([95% confidence interval (CI) 1.24-1.49], P < .0001) but not revision for infection: HR 1.06 ([95% CI 0.90-1.25], P = .52). When comparing implants within a single company, MB-TKAs were at an increased risk of all-cause revision: HR 1.55 ([95% CI 1.38-1.73], P < .0001). Event-free survival curves demonstrated increased risk for all-cause revision for MB-TKA across all time points, with a greater magnitude of risk up to 8 years. CONCLUSION: Although survivorship of both designs was outstanding, MB-TKA designs demonstrated increased risk for all-cause revision. Additional investigation is needed to determine if this is related to patient selection factors, surgical technique, bearing, or implant design.

Could Novel Radiographic Findings Help Identify Aseptic Tibial Loosening?

BACKGROUND: Aseptic loosening following total knee arthroplasty remains one of the leading causes of long-term failure. Radiographic identification of loose implants can be challenging with standard views. The purpose of this study was to compare the incidence of novel radiographic findings of anterior heterotopic bone formation and medial or lateral cyst formation in patients who have aseptic loosening to patients who have well-fixed implants. METHODS: A retrospective radiographic review was performed on 48 patients' revised secondary to aseptic tibial loosening. This cohort was compared to two additional cohorts; 48 patients returning for routine postoperative follow-up (control 1), and 48 patients revised secondary to infection or instability who had well-fixed implants (control 2). RESULTS: There were 41 of 48 (85%) patients who had implant loosening and were noted to have anterior heterotopic bone formation compared to 1 of 48 (2%) patients in control 1 and 3 of 48 (6%) patients in control 2 (P ≤ .0001). There were 43 of 48 (90%) patients who had implant loosening and had medial cyst formation compared to 3 of 48 (6%) patients in control 1 and 5 of 48 (10%) in control 2 (P ≤ .0001). There were 42 of 48 (88%) patients who had implant loosening and had lateral cyst formation compared to 2 of 48 (4%) patients in control 1 and 4 of 48 (8%) in control 2 (P ≤ .0001). CONCLUSION: In this study, we describe novel radiographic findings of anterior heterotopic bone formation and cysts that develop in patients who have aseptic loosening following primary total knee arthroplasty. We believe that these radiographic features may lead to easier identification of aseptic loosening.

How Does the Effect of the Comprehensive Care for Joint Replacement Model Vary Based on Surgical Volume and Costs of Care?

BACKGROUND: The Center for Medicare and Medicaid Innovation revised the comprehensive Care for Joint Replacement (CJR) program, a mandatory 90-day bundled payment for lower extremity joint replacement, in December 2017, retaining 34 of the original 67 metropolitan statistical areas with higher volume and historic episode payments. OBJECTIVES: We describe differences in costs, quality, and patient selection between hospitals that continued to participate compared with those that withdrew from CJR before and after the implementation of CJR. RESEARCH DESIGN: We used a triple difference approach to compare the magnitude of the policy effect for elective admissions between hospitals that were retained in the CJR revision or not, before and after the implementation of CJR, and compared with hospitals in nonparticipant metropolitan statistical areas. SUBJECTS: 694,275 Medicare beneficiaries undergoing elective lower extremity joint replacement from January 1, 2013 to August 31, 2017. MEASURES: The treatment effect heterogeneity of CJR. RESULTS: Hospitals retained in the CJR policy revision had a greater reduction in 90-day episode-of-care cost compared with those that were allowed to discontinue (-$846, 95% CI: -$1,338, -$435) and had greater cost reductions in the more recent year (2017). We also found evidence that retained CJR hospitals disproportionately reduced treating patients who were older than 85 years. CONCLUSIONS: Hospitals that continued to participate in CJR after the policy revision achieved a greater cost reduction. However, the cost reductions were partly attributed to avoiding potential higher - cost patients, suggesting that a bundled payment policy might induce disparities in care delivery.