Fretting and Tribocorrosion of Modular Dual Mobility Liners: Role of Design, Microstructure, and Malseating.

BACKGROUND: Modular dual mobility (DM) bearings have a junction between a cobalt chrome alloy (CoCrMo) liner and titanium shell, and the risk of tribocorrosion at this interface remains a concern. The purpose of this study was to determine whether liner malseating and liner designs are associated with taper tribocorrosion. METHODS: We evaluated 28 retrieved modular DM implants with a mean in situ duration of 14.6 months (range, 1 to 83). There were 2 manufacturers included (12 and 16 liners, respectively). Liners were considered malseated if a distinct divergence between the liner and shell was present on postoperative radiographs. Tribocorrosion was analyzed qualitatively with the modified Goldberg Score and quantitatively with an optical coordinate-measuring machine. An acetabular shell per manufacturer was sectioned for metallographic analysis. RESULTS: There were 6 implants (22%) that had severe grade 4 corrosion, 6 (22%) had moderate grade 3, 11 (41%) had mild grade 2, and 5 (18.5%) had grade 1 or no visible corrosion. The average volumetric material loss at the taper was 0.086 ± 0.19 mm3. There were 7 liners (25%) that had radiographic evidence of malseating, and all were of a single design (P = .01). The 2 liner designs were fundamentally different from one another with respect to the cobalt chrome alloy type, taper surface finish, and shape deviations. Malseating was an independent risk factor for increased volumetric material loss (P = .017). CONCLUSIONS: DM tribocorrosion with quantifiable material loss occurred more commonly in malseated liners. Specific design characteristics may make liners more prone to malseating, and the interplay between seating mechanics, liner characteristics, and patient factors likely contributes to the shell/liner tribocorrosion environment. LEVEL OF EVIDENCE: Level III.

The Ideal Timing of Bilateral Total Knee Arthroplasty: Simultaneous Versus Staged.

Objectives: The ideal timing for patients undergoing bilateral total knee arthroplasty (TKA) remains unknown. The purpose of this study was to compare 90-day outcomes between unilateral, simultaneous bilateral, and staged bilateral TKA. Methods: The PearlDiver database was used to retrospectively identify 231,119 patients undergoing primary TKA during 2015-2020, of which 67,956 (29.4%) were bilateral. Bilateral TKA patients were divided into cohorts of simultaneous bilateral TKA and staged bilateral TKA at 1-14 days, 15-30 days, 31-90 days, and 91-365 days. Each bilateral TKA cohort underwent one-to-one matching with unilateral TKA patients based on age, gender, year, Elixhauser Comorbidity Index (ECI), and a history of obesity, diabetes, and tobacco use. Ninety-day outcomes were compared between matched groups via univariate and multivariate analysis. In staged bilateral TKA groups, outcomes were collected beginning after the second TKA. Results: Compared to unilateral TKA, simultaneous bilateral TKA was associated with higher rates of venous thromboembolism (VTE; odds ratio [OR] 1.28, 95% confidence interval [CI] 1.07-1.54, p=0.007), acute kidney injury (AKI; OR 1.47, CI 1.17-1.84, p=0.001), blood transfusion (OR 6.81, CI 5.43-8.65, p<0.001), and any complication (OR 1.63, CI 1.49-1.78, p<0.001). Staged bilateral TKA at any time interval studied was associated with a similar or decreased risk of individual complications, emergency department visits, readmissions, reoperations, and any complication relative to unilateral TKA. Conclusion: Simultaneous bilateral TKA is associated with an increased risk of adverse events compared to unilateral TKA. However, bilateral TKA staged at a short interval appears safe in appropriately selected patients.

Body Mass Index Does Not Drive the Risk for Early Postoperative Instability After Total Hip Arthroplasty: A Matched Cohort Analysis.

BACKGROUND: Instability remains the leading cause of revision following total hip arthroplasty (THA). The objective of the present investigation was to determine whether an elevated body mass index (BMI) is associated with an increased risk of instability after primary THA. METHODS: An administrative claims database was queried for patients undergoing elective, primary THA for osteoarthritis between 2010 and 2022. Patients who underwent THA for a femoral neck fracture were excluded. Patients who had an elevated BMI were grouped into the following cohorts: 25 to 29.9 (n = 2,313), 30 to 34.9 (n = 2,230), 35 to 39.9 (n = 1,852), 40 to 44.9 (n = 1,450), 45 to 49.9 (n = 752), and 50 to 59.9 (n = 334). Patients were matched 1:1 based on age, sex, and Elixhauser Comorbidity Index, as well as a history of spinal fusion, neurodegenerative disorders, and alcohol abuse, to controls with a normal BMI (20 to 24.9). A multivariate logistic regression controlling for age, sex, Elixhauser Comorbidity Index, and additional risk factors for dislocation was used to evaluate dislocation rates at 30 days, 90 days, 6 months, 1 year, and 2 years. Rates of revision for instability were similarly compared at 1 year and 2 years postoperatively. RESULTS: No significant differences in dislocation rate were observed between control patients and each of the evaluated BMI classes at all evaluated postoperative intervals (all P values > .05). Similarly, the risk of revision for instability was comparable between the normal weight cohort and each evaluated BMI class at 1 year and 2 years postoperatively (all P values > .05). CONCLUSIONS: Controlling for comorbidities and known risk factors for instability, the present analysis demonstrated no difference in rates of dislocation or revision for instability between normal-weight patients and those in higher BMI classes.

Three Differing Methods of Treating Intraoperative Nondisplaced Calcar Fractures Demonstrate Similar Radiographic Stem Subsidence.

BACKGROUND: Several management strategies have been described to treat intraoperative calcar fractures during total hip arthroplasty (THA), including retaining the primary implant and utilizing cerclage cables (CCs) or switching the implant to one that bypasses the fracture and achieves diaphyseal fixation. However, the radiographic and clinical outcomes of these differing strategies have never been described and compared. METHODS: We retrospectively identified 50 patients who sustained an intraoperative calcar fracture out of 9,129 primary total hip arthroplasties (0.55%) performed by one of three surgeons between 2008 and 2022. Each of the three surgeons consistently employed a distinct strategy for the management of these fractures: retention of the primary metaphyseal-engaging implant and placement of CCs; exchange to a modular, tapered-fluted stem (MTF); or exchange to a fully-coated, diaphyseal-engaging stem (FC). Stem subsidence was then evaluated on standing anteroposterior pelvis radiographs at three months and one year postoperatively. Postoperative medical and surgical complication rates were evaluated. RESULTS: A total of fifteen patients were treated with CC, 15 with MTF, and 20 with FC. At three-month follow-up, mean stem subsidence was 0.43 ± 0.08 mm, 1.47 ± 0.36 mm, and 0.68 ± 0.39 mm for CC, MTF, and FC cohorts, respectively (P = .323). At one-year, mean stem subsidence was 0.70 ± 0.08 mm, 1.74 ± 0.69 mm, and 1.88 ± 0.90 mm for the CC, MTF, and FC cohorts, respectively (P = .485). Medical complications included 2 venous thromboembolic events (4%) within 90 days of surgery. There were 6 reoperations (12%); 3 (6%) for acute periprosthetic joint infection (all within the FC cohort); 2 (4%) for postoperative periprosthetic fractures (one fracture distal to the stem in the FC cohort and one fracture at the level of the stem in the MTF cohort), and 1 (2%) closed reduction for instability (within the CC cohort). CONCLUSIONS: The three described methods of managing intraoperative nondisplaced calcar fractures demonstrated little radiographic stem subsidence; however, the risk of reoperation was much higher than expected.

Advanced Concepts in Outpatient Joint Arthroplasty.

As the adoption and utilization of outpatient total joint arthroplasty continues to grow, key developments have enabled surgeons to safely and effectively perform these surgeries while increasing patient satisfaction and operating room efficiency. Here, the authors will discuss the evidence-based principles that have guided this paradigm shift in joint arthroplasty surgery, as well as practical methods for selecting appropriate candidates and optimizing perioperative care. There will be 5 core efficiency principles reviewed that can be used to improve organizational management, streamline workflow, and overcome barriers in the ambulatory surgery center. Finally, future directions in outpatient surgery at the ASC, including the merits of implementing robot assistance and computer navigation, as well as expanding indications for revision surgeries, will be debated.

The Chitranjan S. Ranawat Award: Manipulation Under Anesthesia to Treat Postoperative Stiffness After Total Knee Arthroplasty: A Multicenter Randomized Clinical Trial.

BACKGROUND: Manipulation under anesthesia (MUA) occurs in 4% of patients after total knee arthroplasty (TKA). Anti-inflammatory medications may target arthrofibrosis pathogenesis, but the data are limited. This multicenter randomized clinical trial investigated the effect of adjuvant anti-inflammatory medications with MUA and physical therapy on range of motion (ROM) and outcomes. METHODS: There were 124 patients (124 TKAs) who developed stiffness after primary TKA for osteoarthritis enrolled across 15 institutions. All received MUA when ROM was < 90° at 4 to 12 weeks postoperatively. Randomization proceeded via a permuted block design. Controls received MUA and physical therapy, while the treatment group also received one dose of pre-MUA intravenous dexamethasone (8 mg) and 14 days of oral celecoxib (200 mg). The ROM and clinical outcomes were assessed at 6 weeks and 1 year. This trial was registered with ClinicalTrials.gov. RESULTS: The ROM significantly improved a mean of 46° from a pre-MUA ROM of 72 to 118° immediately after MUA (P < .001). The ROM was similar between the treatment and control groups at 6 weeks following MUA (101 versus 99°, respectively; P = .35) and at one year following MUA (108 versus 108°, respectively; P = .98). Clinical outcomes were similar at both end points. CONCLUSIONS: In this multicenter randomized clinical trial, the addition of intravenous dexamethasone and a short course of oral celecoxib after MUA did not improve ROM or outcomes. However, MUA provided a mean ROM improvement of 46° immediately, 28° at 6 weeks, and 37° at 1 year. Further investigation in regards to dosing, duration, and route of administration of anti-inflammatory medications remains warranted. LEVEL OF EVIDENCE: Level 1, RCT.

Chat Generative Pretrained Transformer (ChatGPT) and Bard: Artificial Intelligence Does not yet Provide Clinically Supported Answers for Hip and Knee Osteoarthritis.

BACKGROUND: Advancements in artificial intelligence (AI) have led to the creation of large language models (LLMs), such as Chat Generative Pretrained Transformer (ChatGPT) and Bard, that analyze online resources to synthesize responses to user queries. Despite their popularity, the accuracy of LLM responses to medical questions remains unknown. This study aimed to compare the responses of ChatGPT and Bard regarding treatments for hip and knee osteoarthritis with the American Academy of Orthopaedic Surgeons (AAOS) Evidence-Based Clinical Practice Guidelines (CPGs) recommendations. METHODS: Both ChatGPT (Open AI) and Bard (Google) were queried regarding 20 treatments (10 for hip and 10 for knee osteoarthritis) from the AAOS CPGs. Responses were classified by 2 reviewers as being in "Concordance," "Discordance," or "No Concordance" with AAOS CPGs. A Cohen's Kappa coefficient was used to assess inter-rater reliability, and Chi-squared analyses were used to compare responses between LLMs. RESULTS: Overall, ChatGPT and Bard provided responses that were concordant with the AAOS CPGs for 16 (80%) and 12 (60%) treatments, respectively. Notably, ChatGPT and Bard encouraged the use of non-recommended treatments in 30% and 60% of queries, respectively. There were no differences in performance when evaluating by joint or by recommended versus non-recommended treatments. Studies were referenced in 6 (30%) of the Bard responses and none (0%) of the ChatGPT responses. Of the 6 Bard responses, studies could only be identified for 1 (16.7%). Of the remaining, 2 (33.3%) responses cited studies in journals that did not exist, 2 (33.3%) cited studies that could not be found with the information given, and 1 (16.7%) provided links to unrelated studies. CONCLUSIONS: Both ChatGPT and Bard do not consistently provide responses that align with the AAOS CPGs. Consequently, physicians and patients should temper expectations on the guidance AI platforms can currently provide.

Bisphosphonate Use May be Associated With an Increased Risk of Periprosthetic Hip Fracture.

BACKGROUND: Osteoporosis is common among patients undergoing primary total hip arthroplasty (THA). This study aimed to evaluate the effect of bisphosphonate treatment on osteoporotic patients undergoing primary THA. METHODS: Using a national database, 30,137 patients who had osteoporosis before primary elective THA were identified during 2010 to 2020. Patients undergoing nonelective THA and those using corticosteroids or other medications for osteoporosis were excluded. Bisphosphonate users and bisphosphonate naïve patients were matched 1:1 based on age, sex, Elixhauser comorbidity index, and a history of obesity, rheumatoid arthritis, tobacco use, and alcohol abuse. Kaplan-Meier and multivariate analyses were used to compare 2-year outcomes between groups. RESULTS: Among matched cohorts of 9,844 patients undergoing primary THA, bisphosphonate use was associated with a significantly higher 2-year rate of periprosthetic fracture (odds ratio 1.29, 95% confidence interval 1.04 to 1.61, P = .022). There was a trend toward increased risk of any revision with bisphosphonate use (odds ratio 1.19, confidence interval 1.00 to 1.41, P = .056). Rates of infection, aseptic loosening, dislocation, and mortality were not statistically different between bisphosphonate users and bisphosphonate-naïve patients. CONCLUSION: In osteoporotic patients, bisphosphonate use before primary THA is an independent risk factor for periprosthetic fracture. Additional longer-term data are needed to determine the underlying mechanism for this association and identify preventative measures.

Strikingly High Rates of Periprosthetic Joint Infection Following Revision Surgery for Periprosthetic Fractures Regardless of Surgery Timing.

BACKGROUND: Periprosthetic fractures following total hip arthroplasty (THA) often occur in the early postoperative period. Recent data has indicated that early revisions are associated with higher complication rates, particularly periprosthetic joint infection (PJI). The purpose of this study was to assess the effect of timing of periprosthetic fracture surgery on complication rates. We hypothesized that complication rates would be significantly higher in revision surgeries performed within 3 months of the index THA. METHODS: The Medicare Part A claims database was queried from 2010 to 2017 to identify patients who underwent surgery for a periprosthetic fracture following primary THA. Patients were divided based on time between index and revision surgeries: <1, 1 to 2, 2 to 3, 3 to 6, 6 to 9, 9 to 12, and >12 months. Complication rates were compared between groups using multivariate analyses to adjust for demographics, comorbidities, and types of revision surgery. RESULTS: Of 492,340 THAs identified, 4,368 (0.9%) had a subsequent periprosthetic fracture requiring surgery: 1,725 (39.4%) at <1 month, 693 (15.9%) at 1 to 2 months, 202 (4.6%) at 2 to 3 months, 250 (5.7%) at 3 to 6 months, 134 (3.1%) at 6 to 9 months, 85 (19.4%) at 9 to12 months, and 1,279 (29.3%) at >12 months. The risk of PJI was 11.0% in the <1 month group, 11.1% at 1 to 2 months, 7.9% at 2 to 3 months, 6.8% at 3 to 6 months, 8.2% at 6 to 9 months, 9.4% at 9 to 12 months, and 8.5% at >12 months (P = .12). Adjusting for confounding factors, risk of PJI following periprosthetic fracture surgery was similar regardless of timing (P > .05). Rates of subsequent dislocation and aseptic loosening were also similar regardless of timing. CONCLUSIONS: The risk of PJI following repeat surgery for a periprosthetic fracture was strikingly high regardless of timing (6.8 to 11.1%), underscoring the high-risk of complications.

Hypoalbuminemia Increases Mortality after Two-Stage Revision Total Joint Arthroplasty.

Objectives: This study aimed to evaluate the effect of hypoalbuminemia on failure rates and mortality after a two-stage revision for PJI. Methods: 199 Patients (130 knees and 69 hips) with a mean age of 64.7 ± 10.7 years who underwent a two-stage exchange were retrospectively reviewed at a mean of 51.2 ± 39.7 months. Failure of treatment was defined as any revision within the follow-up period, failure to undergo reimplantation, or death within one year of initiating treatment. Results: There were 71 failures (35.7%), including 38 septic failures (19.1%). We found no differences between successful revisions and failures regarding hypoalbuminemia (43% vs. 42% prior to stage 1, P=1 and 32% vs. 29% prior to stage 2, P=0.856). There were also no differences in hypoalbuminemia rates between septic failures and the rest of the cohort (42% vs. 43% prior to stage 1, P=1.0 and 34% vs. 30% prior to stage 2, P=0.674). Hypoalbuminemia prior to stage 2 was a significant predictor of mortality based on multivariate analysis (odds ratio 5.40, CI 1.19-24.54, P=0.029). Hypoalbuminemia was independently associated with a greater length of stay by 2.2 days after stage 1 (P=0.002) and by 1.0 days after the second stage reimplantation (P=0.004). Conclusion: Preoperative hypoalbuminemia is a significant predictor of mortality and increased length of stay following two-stage revision but is not a predictor of failure of PJI treatment. Further study is required to understand if hypoalbuminemia is a modifiable risk factor or a marker for poor outcomes.

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.

Dual-Mobility versus Large Femoral Heads in Revision Total Hip Arthroplasty: Interim Analysis of a Randomized Controlled Trial.

BACKGROUND: This multicenter randomized controlled trial evaluated if dual-mobility bearings (DM) lower the risk of dislocation compared to large femoral heads (≥36 mm) for patients undergoing revision total hip arthroplasty (THA) via a posterior approach. METHODS: A total of 146 patients were randomized to a DM (n = 76; 46 mm median effective head size, range 36 to 59 mm) or a large femoral head (n = 70; twenty-five 36 mm heads [35.7%], forty-one 40 mm heads [58.6%], and four 44 mm heads [5.7%]). There were 71 single-component revisions (48.6%), 39 both-component revisions (26.7%), 24 reimplantations of THA after 2-stage revision (16.4%), seven isolated head and liner exchanges (4.8%), four conversions of hemiarthroplasty (2.7%), and 1 revision of a hip resurfacing (0.7%). Power analysis determined that 161 patients were required in each group to lower the dislocation rate from 8.4 to 2.2% (power = 0.8, alpha = 0.05). RESULTS: At a mean of 18.2 months (range, 1.4 to 48.2), there were three dislocations in the large femoral head group compared to two in the DM cohort (4.3 versus 2.6%; P = .67). One patient in the large head group and none in the DM group were successfully treated with closed reduction without subsequent revision. CONCLUSION: Interim analysis of this randomized controlled trial found no difference in the risk of dislocation between DM and large femoral heads in revision THA, although the rate of dislocation was lower than anticipated and continued follow-up is needed.

High rate of failure after revision extensor mechanism allograft reconstruction.

BACKGROUND: Patients who fail initial extensor mechanism allograft (EMA) reconstruction for extensor mechanism disruption after total knee arthroplasty (TKA) are left with few options. This study evaluated outcomes in patients that underwent revision EMA reconstruction following a failed EMA. METHOD: Ten patients that underwent revision EMA for failed index EMA with minimum 1-year follow-up were retrospectively reviewed. Patients receiving fresh-frozen EMA (quadriceps tendon, patella, patellar tendon, and tibial tubercle) at index and revision EMA were included. The primary outcome was EMA failure defined as revision surgery, extensor lag > 30°, or Knee Society Score (KSS) < 60 at last follow-up. Descriptive statistics were performed, with p < 0.05. RESULTS: Mean extensor lag improved from 55.6°±26.7° pre-revision to 32.8°±29.6° (p = 0.13) at mean follow-up of 43.8 months (range, 12-124 months). Mean KSS improved from 41.0 ±â€¯9.5 pre-revision to 73.4 ±â€¯14.5 at last follow-up (p < 0.001). All patients required assistive devices for ambulation at final follow-up: one (10.0%) required a wheelchair, five (50.0%) required a walker, and four (40.0%) required a cane. Seven (70.0%) patients experienced EMA failure at a mean of 33.6 months (range, 2-124) following revision EMA: three (30.0%) were revised for periprosthetic joint infection (one of which also had extensor lag > 30°), three (30.0%) additional patients had extensor lag > 30°, and one (10.0%) patient had KSS < 60 (this patient developed PJI and was treated nonoperatively with chronic antibiotic suppression). CONCLUSIONS: Revision EMA reconstruction fails at a high rate despite leading to improvements in KSS. Further research is needed to develop effective prevention and treatment strategies for failure after initial EMA reconstruction.

Invasive Gastrointestinal Endoscopy Following Total Joint Arthroplasty Increases the Risk for Periprosthetic Joint Infection.

BACKGROUND: The safety of postoperative colonoscopy and endoscopy following total joint arthroplasty (TJA) remains largely unknown. The objective of this study was to characterize the effect of gastrointestinal endoscopic procedures after TJA on the risk of postoperative periprosthetic joint infection (PJI). METHODS: Using a large national database, patients who underwent an endoscopic procedure (colonoscopy or esophagogastroduodenoscopy (EGD)) within 12 months after primary TJA were identified and matched in a 1:1 fashion based on procedure (primary total knee arthroplasty (TKA) versus total hip arthroplasty (THA)), age, sex, Charlson Comorbidity Index (CCI), and smoking status with patients who did not undergo endoscopy. A total of 142,055 patients who underwent endoscopy within 12 months following TJA (96,804 TKAs and 45,251 THAs) were identified and matched. The impact of timing of endoscopy relative to TJA on postoperative outcomes was assessed. Preoperative comorbidity profiles and 1-year complications were compared. Statistical analyses included Chi-squared tests and multivariate logistic regressions with outcomes considered significant at P < .05. RESULTS: Multivariate analyses revealed that endoscopy within 2 months following TKA and 1 month of THA was associated with a significantly increased odds of periprosthetic joint infection (odds ratio (OR): 1.29 [1.08-1.53]; P = .004; OR: 1.41 [1.01-1.90]; P = .033, respectively). Patients who underwent endoscopy greater than 2 months from the timing of their TKA and 1 month from THA were not at significantly greater risk of developing PJI. CONCLUSION: These data suggest that invasive endoscopic procedures should be delayed if possible by at least 2 months following TKA and 1 month following THA to minimize the risk of PJI.

Cementless Total Knee Arthroplasty is Associated With Early Aseptic Loosening in a Large National Database.

BACKGROUND: Despite excellent longevity demonstrated in institutional studies, outcomes after cementless total knee arthroplasty (TKA) on a population level remain unknown. This study compares 2-year outcomes between cemented and cementless TKA using a large national database. METHODS: A large national database was used to identify 294,485 patients undergoing primary TKA from January 2015 to December 2018. Patients who had osteoporosis or inflammatory arthritis were excluded. Cementless and cemented TKA patients were matched one-to-one based on age, Elixhauser Comorbidity Index, sex, and year yielding matched cohorts of 10,580 patients. Outcomes at 90 days, 1 year, and 2 years postoperatively were compared between groups, and Kaplan-Meier analysis was used to evaluate implant survival rates. RESULTS: At 1 year postoperatively, cementless TKA was associated with an increased rate of any reoperation (odds ratio [OR] 1.47, 95% confidence interval [CI] 1.12-1.92, P = .005) compared to cemented TKA. At 2 years postoperatively, there was an increased risk of revision for aseptic loosening (OR 2.34, CI 1.47-3.85, P < .001) and any reoperation (OR 1.29, CI 1.04-1.59, P = .019) after cementless TKA. Two-year revision rates for infection, fracture, and patella resurfacing were similar between cohorts. CONCLUSION: In this large national database, cementless fixation is an independent risk factor for aseptic loosening requiring revision and any reoperation within 2 years after primary TKA.

Outpatient Total Knee Arthroplasty Shows Decreasing Complication Burden From 2010 to 2020.

BACKGROUND: The number of total knee arthroplasties (TKAs) performed on an outpatient basis continues to increase. The purpose of this study was to compare complication rates over the last decade to evaluate trends in the safety of outpatient TKA. METHODS: Patients who underwent TKA from 2010 to 2020 from a large administrative claims database were retrospectively identified and stratified based on the year of surgery. Propensity-score matching was performed to match patients who were discharged within 24 hours of surgery to inpatients based on age, sex, comorbidity index, and year of surgery. Linear regression analyses were used to compare trends from 2010 to 2020. The 90-day adverse events in the early cohort (2010-2012) were compared to those in the late cohort (2018-2020) using multivariable regression analyses. Of the 547,137 patients in the sample, 28,951 outpatients (5.3%) were propensity matched to inpatients. RESULTS: The incidence of outpatient TKA increased from 2010 to 2018 (1.9 versus 13.8%, P < .001). Despite a similar complication rate early (24.1 versus 22.6%, P = .164), outpatient TKA had fewer complications at the end of the study period (13.7 versus 16.7%, P < .001). Multivariate analyses demonstrated that the risk of any complication after outpatient TKA was lower than inpatient from 2018 to 2020 (odds ratio, 0.78; 95% confidence interval, 0.71-0.84). CONCLUSIONS: Complications in both cohorts declined dramatically suggesting improvements in quality of care over time, with the greatest decline in patients undergoing outpatient surgery. These results suggest that outpatient TKA today is not higher risk for the patient than inpatient TKA. LEVEL OF EVIDENCE: Level III.

Elective Joint Arthroplasty Should be Delayed by One Month After COVID-19 Infection to Prevent Postoperative Complications.

BACKGROUND: It remains unclear whether a history of recent COVID-19 infection affects the outcomes and risks of complications of total joint arthroplasty (TJA). The purpose of this study was to compare the outcomes of TJA in patients who have and have not had a recent COVID-19 infection. METHODS: A large national database was queried for patients undergoing total hip and total knee arthroplasty. Patients who had a diagnosis of COVID-19 within 90-days preoperatively were matched to patients who did not have a history of COVID-19 based on age, sex, Charlson Comorbidity Index, and procedure. A total of 31,453 patients undergoing TJA were identified, of which 616 (2.0%) had a preoperative diagnosis of COVID-19. Of these, 281 COVID-19 positive patients were matched with 281 patients who did not have COVID-19. The 90-day complications were compared between patients who did and did not have a diagnosis of COVID-19 at 1, 2, and 3 months preoperatively. Multivariate analyses were used to further control for potential confounders. RESULTS: Multivariate analysis of the matched cohorts showed that COVID-19 infection within 1 month prior to TJA was associated with an increased rate of postoperative deep vein thrombosis (odds ratio [OR]: 6.50, 95% confidence interval: 1.48-28.45, P = .010) and venous thromboembolic events (odds ratio: 8.32, confidence interval: 2.12-34.84, P = .002). COVID-19 infection within 2 and 3 months prior to TJA did not significantly affect outcomes. CONCLUSION: COVID-19 infection within 1 month prior to TJA significantly increases the risk of postoperative thromboembolic events; however, complication rates returned to baseline after that time point. Surgeons should consider delaying elective total hip arthroplasty and total knee arthroplasty until 1 month after a COVID-19 infection.

Short-Term Indwelling Foley Catheters Do Not Reduce the Risk of Postoperative Urinary Retention in Uncomplicated Primary THA and TKA: A Randomized Controlled Trial.

BACKGROUND: The purpose of this randomized controlled trial was to determine whether a short-term Foley catheter (inserted in the operating room and removed upon arrival to the orthopaedic floor) would reduce the risk of postoperative urinary retention (POUR) in patients undergoing primary total hip (THA) and total knee arthroplasty (TKA). METHODS: Three hundred and eighty-eight patients undergoing inpatient primary TKA (n = 228) or THA (n = 160) with spinal anesthesia were randomized to receive a short-term Foley catheter (n = 194) or no Foley (n = 194). There were 143 male and 245 female patients. The primary outcome was POUR, defined as requiring ≥2 straight catheterizations or the placement of an indwelling urinary catheter when indicated by retention of ≥450 mL on bladder scans. Secondary outcomes included urinary tract infections (UTIs) within 3 weeks and the need for ≥1 straight catheterization. A power analysis determined that 194 patients per group were required to detect a 7% minimal clinically important difference in POUR rates at 80% power and alpha of 0.05. Intention-to-treat and as-treated analyses were performed (2 patients received the non-allocated treatment). Outcomes were compared between the groups using univariate and multivariate analyses, with alpha < 0.05. RESULTS: Nine patients developed POUR: 4 in the short-term Foley group and 5 in the control group (2.1% versus 2.6%; p = 1.00). Of those who developed POUR, 8 were male and 1 was female (88.9% versus 11.1%; p = 0.002). Twenty-four patients required ≥1 straight catheterization: 10 in the Foley group and 14 in the control group (5.2% versus 7.2%; p = 0.40). Four patients developed UTIs: 3 in the Foley group and 1 in the control group (1.5% versus 0.5%; p = 0.62) on intention-to-treat analysis, and 4 in the Foley group and none in the control group (2.1% versus 0.0%; p = 0.12) on as-treated analysis. CONCLUSIONS: The use of a short-term Foley catheter inserted in the operating room and removed on arrival to the orthopaedic floor does not decrease the rate of POUR. LEVEL OF EVIDENCE: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Complications and costs of patellofemoral arthroplasty versus total knee arthroplasty.

BACKGROUND: Patellofemoral arthroplasty (PFA) is an alternative to total knee arthroplasty (TKA) for the treatment of patellofemoral arthritis. Although PFA may preserve native kinematics and accelerate recovery, it has been associated with higher revision rates. The purpose of this study is to compare complication rates and costs between PFA and TKA. METHODS: Using the PearlDiver database, 6,179 patients with isolated patellofemoral arthritis treated with PFA or TKA from 2010-2015 were retrospectively reviewed with 5-year follow up. PFA and TKA patients were matched by age, sex, and Elixhauser Comorbidity Index via a 1:1 stepwise algorithm. Five-year costs and complications were compared between matched cohorts. The lifetime costs of PFA and TKA were evaluated with Markov decision modeling. RESULTS: Compared to TKA, PFA was associated with fewer Emergency Department (ED) visits (6.1% vs 3.9%, p = 0.004) but a higher 5-year revision rate (9.9% vs 4.2%, p < 0.001). After multivariate regression, PFA was independently more likely to require revision (odds ratio 2.60, 95% confidence interval 1.32-4.71, p = 0.003). PFA was associated with lower total healthcare costs at every time point between 3 months ($18,014 vs $26,473, p < 0.001) and 5 years ($20,837 vs $27,942, p < 0.001). On average, the lifetime cost of PFA per patient was $5,235 less than for TKA ($26,343 vs $31,578). CONCLUSIONS: PFA is a less expensive alternative to TKA with a similar risk of medical complications but is associated with a significantly higher 5-year revision rate. Future studies should examine the reasons for PFA failure and methods to mitigate this risk.

Hot Topics and Current Controversies in Total Knee Arthroplasty.

Total knee arthroplasty continues to evolve. It is important to review some of the current controversies and hot topics in arthroplasty. Optimal knee alignment strategy is now just a matter of debate. Mechanical, kinematic, and functional alignment and the role of robotics in achieving optimum alignment are important topics, along with fixation and outpatient knee arthroplasty.