Practical Artificial Intelligence: Realistic Ways It Can Help Orthopaedic Surgeons and the Challenges It Will Face.

Artificial intelligence can improve various orthopaedic subspecialties in the next 5 to 10 years. There are several image recognition applications particularly in orthopedic trauma and orthopedic spine. Specifically, convolutional neural networks have been shown to work well for making diagnoses and recreating more advanced imaging form radiographs. There are many applications of artificial intelligence with predictive in total joint arthroplasty, particularly with shared decision making. And there are many day-to-day applications that can be improved with natural language processing, particularly administrative tasks. This includes several applications in billing and charting. When investigating the landscape of artificial intelligence in healthcare, there are many barriers to their adoption. This includes overcoming bias, incorporating new applications into clinical workflow, regulatory approval, and billing.

No Correlation Between Clinical Outcomes and Changes in the Tibia-Metaphyseal Angle Following Total Knee Arthroplasty: A Retrospective Study.

BACKGROUND: Despite numerous advances in the implant design and surgical technique, improvement in patient satisfaction following total knee arthroplasty (TKA) has plateaued. Various TKA alignment strategies have been introduced that impact the coronal positioning of the tibial component relative to the native joint line. This study aims to analyze if postoperative variance of the joint line from preoperative native alignment is correlated with changes in patient-reported outcomes following primary TKA. METHODS: A retrospective review of an academic center's patient population identified all primary TKAs between 2013 and 2021 with full-length, standing radiographs and patient-reported outcome measures (PROMs) data. These measures included the Knee injury and Osteoarthritis Outcome Score for Joint Replacement, Patient-Reported Outcome Measurement Information System, and Veterans RAND 12 scores. Preoperative and postoperative radiographic measurements for hip-knee angle, tibia-metaphyseal angle, tibial-axis orientation angle, and joint-line obliquity angle were recorded. Three-month, 1-year, and 2-year PROM scores were correlated with the change in degrees for each of the angles using a Spearman's correlation. A Mann-Whitney U-test was used to compare angular changes with a change in PROM scores. RESULTS: One hundred and ninety nine patients (204 knees) with a mean age of 67 years were included. Average follow-up was 23 months. Three-month, 1-year, and 2-year follow-up rates were 93%, 64%, and 34%, respectively. Improvements were seen across all PROMs regardless of an angular change. CONCLUSION: There were no clear correlations between PROMs and variation in joint line obliquity in the coronal plane. These data suggest that the magnitude of the variation in coronal tibial alignment from native alignment does not impact PROMs. Further study is indicated to correlate an angular change with functional measures.

Impact of fatty degeneration on the functional outcomes of 38 patients undergoing surgical repair of gluteal tendon tears.

BACKGROUND: Gluteal tendon tears (GTT) can cause pain and weakness of the hip. We analyze the impact of gluteal muscle fatty degeneration, atrophy and tear morphology on clinical outcomes of surgical repair. METHODS: All sequential patients receiving surgical repair of GTTs via anchor sutures between 1/2015 and 11/2018 were retrospectively identified. MRIs were reviewed by a radiologist for tendon retraction, muscle atrophy and tear size. The Goutallier-Fuchs Classification (GFC) was used to quantify fatty degeneration as < 2° or ≥ 2°. Demographic and clinical variables were abstracted from the electronic records. The surveys HHS Section 1 and HOOS Jr. were obtained at last follow-up. The Pearson correlation and one-way ANOVA tests served for statistical analysis of clinical variance. RESULTS: 38 patients were identified, 29 (76.3%) were female. The average age was 67. Of the 11 (28.9%) patients with a prior hip arthroplasty 87.5% of primary THAs had a direct lateral approach. 29 (76.3%) patients were treated open and 9 (23.7%) arthroscopically. At an average follow-up of 20.9 months, patients reported a significant improvement in pain (97%), analgesic use (85.7%), limp (52.6%) and abduction strength (54.2%) (all: P ≤ 0.01). GFC ≥ 2° were associated with significantly worse outcomes in terms of limp (0.19/3 vs. 1.2/3, P = 0.05), HHS-S1 (58.19 vs. 71.68, P = 0.04) and complication rates (37.5% vs. 0%, P = 0.02). There was a strong correlation between tear retraction (P = 0.005), tear size (P = 0.009) and muscle atrophy (P = 0.001) with GFC ≥ 2° but not with clinical outcomes. GFC ≥ 2° was strongly related to lateral THA exposures (P < 0.001). Surgical approach had no impact on clinical outcomes. CONCLUSION: While fatty degeneration can negatively impact functional outcomes, pain relief is reliably achieved. Tear morphology and muscle atrophy did not correlate with outcomes in this patient cohort. Patients should be counseled to expect a residual limp after surgery if they have GFC ≥ 2° on MRI.

Risk-Adjusted Cost Performance for 90-Day Total Hip Arthroplasty Episodes: Comparing US Hospitals Nationwide Before CJR.

BACKGROUND: We characterize variation in total hip arthroplasty (THA) episode payments in the United States. Medicare population immediately preceding implementation of the comprehensive care for joint replacement (CJR) bundled care model and propose a model for ongoing evaluation of hospital performance. METHODS: We identified THA episodes in Medicare part A 2014-2016 (n = 366,380) and compared 90-day episode payments across years and geographic regions. We fit hierarchical models that regressed episode payments on patient-level fixed and region-level and hospital-level random effects. Random effects estimates were used to characterize risk-adjusted hospital cost performance. We ranked hospitals (n = 3218) in each region by their cost performance estimate and constructed 95% confidence intervals to visualize high-performing and low-performing hospitals. RESULTS: Mean part A episode payments declined from 2014 to 2016 throughout the United States ($19,925-$17,775; P < .001), primarily attributable to decreased postacute care payments. Ninety-day readmission rates fell by a percentage point (from 7.9% to 6.8%; P < .001). We found significant variation in risk-adjusted episode payments, postacute care utilization, and readmission rates across regions, and ever greater variation at the hospital level. CONCLUSION: Medicare part A payments decreased for THA episodes between 2014 and 2016. The time frame for this decrease is notable for preceding full implementation of CJR, thus suggesting a more universal embrace of value-based care principles before the start date of CJR. These decreases were primarily because of decreased postacute care utilization and possibly related to falling readmission rates. Yet, significant variation in hospital cost performance remains, even after risk adjustment.

Equivalent Mid-Term Results of Open vs Endoscopic Gluteal Tendon Tear Repair Using Suture Anchors in Forty-Five Patients.

BACKGROUND: Little is known about the relative efficacy of open (OGR) vs endoscopic (EGR) gluteal tendon repair of gluteal tendon tears in minimizing pain and restoring function. Our aim is to compare these 2 surgical techniques and quantify their impact on clinical outcomes. METHODS: All patients undergoing gluteal tendon tear repair at our institution between 2015 and 2018 were retrospectively reviewed. Pain scores, limp, hip abduction strength, and the use of analgesics were recorded preoperatively and at last follow-up. The Hip disability and Osteoarthritis Outcome Score Junior and Harris Hip Score Section1 were obtained at last follow-up. Fatty degeneration was quantified using the Goutallier-Fuchs Classification (GFC). Statistical analysis was conducted using one-way analysis of variance and t-tests. RESULTS: Forty-five patients (mean age 66, 87% females) met inclusion criteria. Average follow-up was 20.3 months. None of the 10 patients (22%) undergoing EGR had prior surgery. Of 35 patients (78%) undergoing OGR, 12 (27%) had prior hip replacement (75% via lateral approach). The OGRs had more patients with GFC ≥2 (50% vs 11%, P = .02) and used more anchors (P = .03). Both groups showed statistical improvement (P ≤ .01) for all outcomes measured. GFC >2 was independently associated with a worst limp and Harris Hip Score Section 1 score (P = .05). EGR had a statistically higher opioid use reduction (P < .05) than OGR. Other comparisons between EGR and OGR did not reach statistical significance. CONCLUSION: In this series, open vs endoscopic operative approach did not impact clinical outcomes. More complex tears were treated open and with more anchors. Fatty degeneration adversely impacted outcomes. Although further evaluation of the efficacy of EGR in complex tears is indicated, both approaches can be used successfully.

Risk Adjustment in the California Joint Replacement Registry: Is Patient Complexity Accurately Assessed in Academic Versus Nonacademic Hospitals?

BACKGROUND: We sought to report on the differences in observed versus expected arthroplasty outcomes between academic and nonacademic hospitals in a large joint registry. We utilized the California Joint Replacement Registry's data and risk adjustment model. METHODS: Observed versus expected hip and knee arthroplasty complications were utilized to assess hospital and surgeon risk-adjusted complication rates (RACRs). Based on a hospital and surgeon RACR, each was assigned a performance rating ("worse," "expected," "better"). Associations between academic status and performance ratings, rates of individual complications, prevalence of risk factors associated with increased complication rates, and differences in complication rates were calculated. RESULTS: A higher percentage of academic providers had "worse" than expected ratings, whereas a higher percentage of nonacademic providers had "expected" and "better" than expected ratings (P = .011) based on the observed versus expected complication rates. There was a higher incidence of patients with congestive heart failure and an elevated American Society of Anesthesiologists classification in academic institutions (P = .0001). The complication rate was higher in academic institutions for all total knee arthroplasties (P < .0016). CONCLUSIONS: We identified disparities in RACRs between nonacademic and academic institutions. This may reflect the difficulty of fully adjusting for medical risk and surgical complexity in a large arthroplasty database.

Digital Orthopaedics: A Glimpse Into the Future in the Midst of a Pandemic.

BACKGROUND: The response to COVID-19 catalyzed the adoption and integration of digital health tools into the health care delivery model for musculoskeletal patients. The change, suspension, or relaxation of Medicare and federal guidelines enabled the rapid implementation of these technologies. The expansion of payment models for virtual care facilitated its rapid adoption. The authors aim to provide several examples of digital health solutions utilized to manage orthopedic patients during the pandemic and discuss what features of these technologies are likely to continue to provide value to patients and clinicians following its resolution. CONCLUSION: The widespread adoption of new technologies enabling providers to care for patients remotely has the potential to permanently change the expectations of all stakeholders about the way care is provided in orthopedics. The new era of Digital Orthopaedics will see a gradual and nondisruptive integration of technologies that support the patient's journey through the successful management of their musculoskeletal disease.

Machine Learning Algorithms Can Use Wearable Sensor Data to Accurately Predict Six-Week Patient-Reported Outcome Scores Following Joint Replacement in a Prospective Trial.

BACKGROUND: Tracking patient-generated health data (PGHD) following total joint arthroplasty (TJA) may enable data-driven early intervention to improve clinical results. We aim to demonstrate the feasibility of combining machine learning (ML) with PGHD in TJA to predict patient-reported outcome measures (PROMs). METHODS: Twenty-two TJA patients were recruited for this pilot study. Three activity trackers collected 35 features from 4 weeks before to 6 weeks following surgery. PROMs were collected at both endpoints (Hip and Knee Disability and Osteoarthritis Outcome Score, Knee Osteoarthritis Outcome Score, and Veterans RAND 12-Item Health Survey Physical Component Score). We used ML to identify features with the highest correlation with PROMs. The algorithm trained on a subset of patients and used 3 feature sets (A, B, and C) to group the rest into one of the 3 PROM clusters. RESULTS: Fifteen patients completed the study and collected 3 million data points. Three sets of features with the highest R2 values relative to PROMs were selected (A, B and C). Data collected through the 11th day had the highest predictive value. The ML algorithm grouped patients into 3 clusters predictive of 6-week PROM results, yielding total sum of squares values ranging from 3.86 (A) to 1.86 (C). CONCLUSION: This small but critical proof-of-concept study demonstrates that ML can be used in combination with PGHD to predict 6-week PROM data as early as 11 days following TJA surgery. Further study is needed to confirm these findings and their clinical value.

Optimal Sampling Frequency for Wearable Sensor Data in Arthroplasty Outcomes Research. A Prospective Observational Cohort Trial.

BACKGROUND: Wearable sensors can track patient activity after surgery. The optimal data sampling frequency to identify an association between patient-reported outcome measures (PROMs) and sensor data is unknown. Most commercial grade sensors report 24-hour average data. We hypothesize that increasing the frequency of data collection may improve the correlation with PROM data. METHODS: Twenty-two total joint arthroplasty (TJA) patients were prospectively recruited and provided wearable sensors. Second-by-second (Raw) and 24-hour average data (24Hr) were collected on 7 gait metrics on the 1st, 7th, 14th, 21st, and 42nd days postoperatively. The average for each metric as well as the slope of a linear regression for 24Hr data (24HrLR) was calculated. The R2 associations were calculated using machine learning algorithms against individual PROM results at 6 weeks. The resulting R2 values were defined having a mild, moderate, or strong fit (R2 ≥ 0.2, ≥0.3, and ≥0.6, respectively) with PROM results. The difference in frequency of fit was analyzed with the McNemar's test. RESULTS: The frequency of at least a mild fit (R2 ≥ 0.2) for any data point at any time frame relative to either of the PROMs measured was higher for Raw data (42%) than 24Hr data (32%; P = .041). There was no difference in frequency of fit for 24hrLR data (32%) and 24Hr data values (32%; P > .05). Longer data collection improved frequency of fit. CONCLUSION: In this prospective trial, increasing sampling frequency above the standard 24Hr average provided by consumer grade activity sensors improves the ability of machine learning algorithms to predict 6-week PROMs in our total joint arthroplasty cohort.

Variation in the Thickness of Knee Cartilage. The Use of a Novel Machine Learning Algorithm for Cartilage Segmentation of Magnetic Resonance Images.

BACKGROUND: The variation in articular cartilage thickness (ACT) in healthy knees is difficult to quantify and therefore poorly documented. Our aims are to (1) define how machine learning (ML) algorithms can automate the segmentation and measurement of ACT on magnetic resonance imaging (MRI) (2) use ML to provide reference data on ACT in healthy knees, and (3) identify whether demographic variables impact these results. METHODS: Patients recruited into the Osteoarthritis Initiative with a radiographic Kellgren-Lawrence grade of 0 or 1 with 3D double-echo steady-state MRIs were included and their gender, age, and body mass index were collected. Using a validated ML algorithm, 2 orthogonal points on each femoral condyle were identified (distal and posterior) and ACT was measured on each MRI. Site-specific ACT was compared using paired t-tests, and multivariate regression was used to investigate the risk-adjusted effect of each demographic variable on ACT. RESULTS: A total of 3910 MRI were included. The average femoral ACT was 2.34 mm (standard deviation, 0.71; 95% confidence interval, 0.95-3.73). In multivariate analysis, distal-medial (-0.17 mm) and distal-lateral cartilage (-0.32 mm) were found to be thinner than posterior-lateral cartilage, while posterior-medial cartilage was found to be thicker (0.21 mm). In addition, female sex was found to negatively impact cartilage thickness (OR, -0.36; all values: P < .001). CONCLUSION: ML was effectively used to automate the segmentation and measurement of cartilage thickness on a large number of MRIs of healthy knees to provide normative data on the variation in ACT in this population. We further report patient variables that can influence ACT. Further validation will determine whether this technique represents a powerful new tool for tracking the impact of medical intervention on the progression of articular cartilage degeneration.

Artificial Intelligence, Machine Learning, Deep Learning, and Cognitive Computing: What Do These Terms Mean and How Will They Impact Health Care?

This article was presented at the 2017 annual meeting of the American Association of Hip and Knee Surgeons to introduce the members gathered as the audience to the concepts behind artificial intelligence (AI) and the applications that AI can have in the world of health care today. We discuss the origin of AI, progress to machine learning, and then discuss how the limits of machine learning lead data scientists to develop artificial neural networks and deep learning algorithms through biomimicry. We will place all these technologies in the context of practical clinical examples and show how AI can act as a tool to support and amplify human cognitive functions for physicians delivering care to increasingly complex patients. The aim of this article is to provide the reader with a basic understanding of the fundamentals of AI. Its purpose is to demystify this technology for practicing surgeons so they can better understand how and where to apply it.

Risk Factors for Reaching the Post-Operative Transfusion Trigger in a Community Primary Total Knee Arthroplasty Population.

BACKGROUND: Little data exist to evaluate an individual's pre-operative risk of blood transfusion following total knee arthroplasty (TKA). Our aim is to identify the risk factors associated with reaching the transfusion trigger of Hb <8 g/dL (TT8) following surgery and how perioperative tranexamic acid (TXA) affects that outcome. METHODS: Using a retrospective cohort study design, routine, unilateral TKAs performed between 2011 and 2013 in 19 hospitals were reviewed. Patients hospitalized ≤1 day or ≥4 days were excluded. Demographic data, clinical characteristics, and potential confounders were included in statistical models. Data were abstracted from electronic clinical and utilization databases. The main outcome was the risk of reaching the TT8. The primary exposure was use of single dose intravenous TXA. Logistic regression was used to model the adjusted association between TXA usage and post-operative risk of reaching TT8. RESULTS: A total of 10,518 TKAs met criteria; 2566 (24.3%) received TXA (+TXA). The proportion that reached the TT8 was 2.1% for + TXA and 5.3% for -TXA (P < .0001). Pre-operative Hb levels were associated with increasing odds of reaching the TT8. Increasing age was weakly associated with this outcome. The odds of reaching the TT8 were lower for patients who had received TXA, had increasing body mass index, and surgical duration in the third quartile. CONCLUSION: Not receiving TXA within 24 hours of TKA and pre-operative Hb levels <13 g/dL were independently associated with the odds of reaching the post-operative TT8 following a primary TKA.

The Efficacy of Tranexamic Acid in Total Hip Arthroplasty: A Network Meta-analysis.

BACKGROUND: Tranexamic acid (TXA) is an antifibrinolytic agent commonly used to reduce blood loss in total hip arthroplasty (THA). The purpose of our study was to evaluate the efficacy of TXA in primary THA to support the combined clinical practice guidelines of the American Association of Hip and Knee Surgeons, American Academy of Orthopaedic Surgeons, Hip Society, Knee Society, and American Society of Regional Anesthesia and Pain Medicine on the use of TXA in primary total joint arthroplasty. METHODS: A search was performed using Ovid-MEDLINE, Embase, Cochrane Reviews, Scopus, and Web of Science databases to identify all publications before July 2017 on TXA in primary THA. We completed qualitative and quantitative homogeneity testing of all included studies. Direct and indirect comparisons were analyzed using a network meta-analysis followed by consistency testing of the results. RESULTS: Two thousand one hundred thirteen publications underwent critical appraisal with 34 publications identified as representing the best available evidence for inclusion in the analysis. Topical, intravenous, and oral TXA formulations provided reduced blood loss and risk of transfusion compared to placebo, but no formulation was clearly superior. Use of repeat doses, higher doses, or variation in timing of administration did not significantly reduce blood loss or risk of transfusion. CONCLUSIONS: Strong evidence supports the use of TXA to reduce blood loss and risk of transfusion after primary THA. No specific routes of administration, dosage, dosing regimen, or time of administration provides clearly superior blood-sparing properties.

The Efficacy of Tranexamic Acid in Total Knee Arthroplasty: A Network Meta-Analysis.

BACKGROUND: A growing body of published research on tranexamic acid (TXA) suggests that it is effective in reducing blood loss and the risk for transfusion in total knee arthroplasty (TKA). The purpose of this network meta-analysis was to evaluate TXA in primary TKA as the basis for the efficacy recommendations of the combined clinical practice guidelines of the American Association of Hip and Knee Surgeons, American Academy of Orthopaedic Surgeons, Hip Society, Knee Society, and American Society of Regional Anesthesia and Pain Medicine on the use of TXA in primary total joint arthroplasty. METHODS: We searched Ovid MEDLINE, Embase, Cochrane Reviews, Scopus, and Web of Science databases for publications before July 2017 on TXA in primary total joint arthroplasty. All included studies underwent qualitative and quantitative homogeneity testing. Direct and indirect comparisons were performed as a network meta-analysis, and results were tested for consistency. RESULTS: After critical appraisal of the available 2113 publications, 67 articles were identified as representing the best available evidence. Topical, intravenous (IV), and oral TXA formulations were all superior to placebo in terms of decreasing blood loss and risk of transfusion, while no formulation was clearly superior. Use of repeat IV and oral TXA dosing and higher doses of IV and topical TXA did not significantly reduce blood loss or risk of transfusion. Preincision administration of IV TXA had inconsistent findings with a reduced risk of transfusion but no effect on volume of blood loss. CONCLUSIONS: Strong evidence supports the efficacy of TXA to decrease blood loss and the risk of transfusion after primary TKA. No TXA formulation, dosage, or number of doses provided clearly improved blood-sparing properties for TKA. Moderate evidence supports preincision administration of IV TXA to improve efficacy.

The Safety of Tranexamic Acid in Total Joint Arthroplasty: A Direct Meta-Analysis.

BACKGROUND: Tranexamic acid (TXA) is effective in reducing blood loss in total joint arthroplasty (TJA), but concerns still remain regarding the drug's safety. The purpose of this direct meta-analysis was to evaluate and establish a basis for the safety recommendations of the combined clinical practice guidelines on the use of TXA in primary TJA. METHODS: A search was completed for studies published before July 2017 on TXA in primary TJA. We performed qualitative and quantitative homogeneity testing and a direct comparison meta-analysis. We used the American Society of Anesthesiologists (ASA) score of 3 or greater as a proxy for patients at higher risk for complications in general and performed a meta-regression analysis to investigate the influence of comorbidity burden on the risk of arterial thromboembolic event and venous thromboembolic event (VTE). RESULTS: Topical, intravenous, and oral TXA were not associated with an increased risk of VTE after TJA. In addition, meta-regression demonstrated that TXA use in patients with an ASA status of 3 or greater was not associated with an increased risk of VTE after total knee arthroplasty. CONCLUSION: Although most studies included in our analysis excluded patients with a history of prior thromboembolic events, our findings support the lack of evidence of harm from TXA administration in patients undergoing TJA. Moderate evidence supports the safety of TXA in patients undergoing total knee arthroplasty with an ASA score of 3 or greater. The benefits of using TXA appear to outweigh the potential risks of thromboembolic events even in patients with a higher comorbidity.

Is There a Difference in Revision Risk Between Metal and Ceramic Heads on Highly Crosslinked Polyethylene Liners?

BACKGROUND: The most common bearing surface used among primary THAs worldwide is a metal or ceramic femoral head that articulates against a highly crosslinked ultrahigh-molecular-weight polyethylene (HXLPE) acetabular liner. Despite their widespread use, relatively little is known about the comparative effectiveness of ceramic versus metal femoral heads with respect to risk of revision and dislocation as well as the role of head size in this relationship. QUESTIONS/PURPOSES: The purpose of this study was to evaluate the risk of (1) all-cause revision in metal versus ceramic femoral heads when used with an HXLPE liner, including an evaluation of the effect of head size; and (2) dislocation in metal versus ceramic femoral heads when used with an HXLPE liner as well as an assessment of the effect of head size. METHODS: Data were collected as part of the Kaiser Permanente Total Joint Replacement Registry between 2001 and 2013. Patients in this study were on average overweight (body mass index = 29 kg/m2), 67 years old, mostly female (57%), and had osteoarthritis (93%) as the primary indication for surgery. The material of the femoral head (metal, ceramic) was crossed with head size (< 32, 32, 36, > 36 mm), yielding eight device groupings. Only uncemented devices were evaluated. The primary outcome was all-cause revision (n = 28,772) and the secondary outcome was dislocation within 1 year (n = 19,623). Propensity scores were used to adjust for potential confounding at the implant/patient level using between-within semiparametric survival models that control for surgeon and hospital confounding and adjust estimates for the within-cluster correlation among observations on the response. RESULTS: For all-cause revision, there was no difference between ceramic versus metal (reference) heads in combination with an HXLPE liner (hazard ratio [HR] = 0.82 [0.65-1.04], p = 0.099). Smaller metal head sizes of < 32 mm were associated with increased risk of revision relative to 36 mm (HR = 1.66 [1.20-2.31], p = 0.002, adjusted p = 0.025). For dislocation, ceramic heads increased risk relative to metal at < 32 mm only (HR = 4.39 [1.72-11.19], p = 0.002, adjusted p = 0.020). Head sizes < 32 mm were associated with increased risk of dislocation relative to 36 mm for metal (HR = 2.99 [1.40-6.39], p = 0.005, adjusted p = 0.047) and ceramic heads (HR = 15.69 [6.07-40.55], p < 0.001, adjusted p < 0.001). CONCLUSIONS: The results did not provide evidence for use of one femoral head material over another when used with HXLPE liners for the outcome of revision, but for dislocation, metal performed better than ceramic with < 32-mm heads. Overall, the findings suggest increased risk of revision/dislocation with head sizes < 32 mm. LEVEL OF EVIDENCE: Level III, therapeutic study.

Midterm-Adjusted Survival Comparing the Best Performing Unicompartmental and Total Knee Arthroplasties in a Registry.

BACKGROUND: Recent literature suggests that the difference in revision risk between unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) can be influenced by surgeon volume and other confounders. We hypothesized that implant selection might decrease the relative risk of revision in an adjusted model. METHODS: We selected the best performing (BP) primary UKAs and TKAs performed for osteoarthritis between January 2001 and December 2012 collected through a joint replacement registry. We compared aseptic and all-cause risk of revision using a surgeon-stratified Cox regression model with propensity score adjustment. RESULTS: One thousand fifty-four UKAs were compared with 74,185 TKAs. The rate for all-cause revision was lower for UKAs (2.1%) than for TKAs (2.4%), whereas the rate for aseptic revision was higher for UKAs (2.0%) than TKAs (1.4%). The adjusted risk of aseptic revision was not significantly higher for UKA than TKA (hazard ratio = 2.02 [0.68, 5.96], P = .203) or all-cause revision (hazard ratio = 1.24 [0.52, 2.98], P = .603). CONCLUSION: When comparing the survivorship of the BP UKAs to the BP TKAs in our registry, the adjusted risk of revision remained higher for UKAs than for TKAs, although the difference did not reach statistical significance.

Comparative Effectiveness and Safety of Drug Prophylaxis for Prevention of Venous Thromboembolism After Total Knee Arthroplasty.

BACKGROUND: Rates of venous thromboembolism in contemporary studies of primary total knee arthroplasty (TKA) have been reported to be as high as 3.5%. Although drug prophylaxis is effective, the best option among these regimens is not well established. The purpose of this study was to evaluate the comparative effectiveness and safety of aspirin, low-molecular-weight heparin, synthetic pentasaccharide factor Xa inhibitors, and vitamin K antagonist. METHODS: Data were from a US total joint replacement registry, with 30,499 patients receiving unilateral TKA from May 16, 2006, to December 31, 2013. Patients received either aspirin (324-325 mg daily), enoxaparin (40-60 mg daily), fondaparinux (2.5 mg daily), or warfarin (all doses) and were followed up 90 days postoperatively on several outcomes: deep vein thrombosis, pulmonary embolism, major bleeding, wound complications, infection, and death. RESULTS: There was no evidence that fondaparinux, enoxaparin, or warfarin were superior to aspirin in the prevention of pulmonary embolism, deep vein thrombosis, or venous thromboembolism or that aspirin was safer than these alternatives. However, enoxaparin was found to be as safe as aspirin with respect to bleeding, and fondaparinux was as safe as aspirin for risk of wound complications. CONCLUSION: Among TKA patients, we did not find evidence for decreased effectiveness or increased safety with use of aspirin, but enoxaparin had comparable safety to aspirin for bleeding and fondaparinux had comparable safety to aspirin for wound complications.

Achieving 90% Adoption of Clinical Practice Guidelines Using the Delphi Consensus Method in a Large Orthopedic Group.

BACKGROUND: Little is known about the implementation rate of clinical practice guidelines (CPGs). Our purpose was to report on the adoption rate of CPGs created and implemented by a large orthopedic group using the Delphi consensus method. METHODS: The draft CPGs were created before the group's annual meeting by 5 teams each assigned a subset of topics. The draft guidelines included a statement and a summary of the available evidence. Each guideline was debated in both small-group and plenary sessions. Voting was anonymous and a 75% supermajority was required for passage. A Likert scale was used to survey the patient's experience with the process at 1 week, and the Kirkpatrick evaluation model was used to gauge the efficacy of the process over a 6-month time frame. RESULTS: Eighty-five orthopedic surgeons attended the meeting. Fifteen guidelines grouped into 5 topics were created. All passed. Eighty-six percent of attendees found the process effective and 84% felt that participating in the process made it more likely that they would adopt the guidelines. At 1 week, an average of 62% of attendees stated they were practicing the guideline as written (range: 35%-72%), and at 6 months, 96% stated they were practicing them (range: 82%-100%). CONCLUSION: We have demonstrated that a modified Delphi method for reaching consensus can be very effective in both creating CPGs and leading to their adoption. Further we have shown that the process is well received by participants and that an inclusionary approach can be highly successful.

Antibiotic cement was associated with half the risk of re-revision in 1,154 aseptic revision total knee arthroplasties.

BACKGROUND AND PURPOSE: Aseptic revisions comprise 80% of revision total knee arthroplasties (TKAs). We determined the incidence of re-revision TKA, the reasons for re-revision, and risk factors associated with these procedures. PATIENTS AND METHODS: We conducted a retrospective cohort study of 1,154 patients who underwent aseptic revision TKA between 2002 and 2013 and were followed prospectively by a total joint replacement registry in the USA. Revision was defined as any operation in which an implanted component was replaced. Patient-, surgeon-, and procedure-related risk factors were evaluated. Survival analyses were conducted. RESULTS: There were 114 re-revisions (10%) with a median time to reoperation of 3.6 years (interquartile range (IQR): 2.6-5.2). The infection rate was 2.9% (34/1,154) and accounted for 30% of re-revisions (34 of 114). In adjusted models, use of antibiotic-loaded cement was associated with a 50% lower risk of all-cause re-revision surgery (hazard ratio (HR) = 0.5, 95% CI: 0.3-0.9), age with a 20% lower risk for every 10-year increase (HR = 0.8, CI: 0.7-1.0), body mass index (BMI) with a 20% lower risk for every 5-unit increase (HR = 0.8, CI: 0.7-1.0), and a surgeon's greater cumulative experience (≥ 20 cases vs. < 20 cases) with a 3 times higher risk of re-revision (HR = 2.8, CI: 1.5-5). INTERPRETATION: Revised TKAs were at high risk of subsequent failure. The use of antibiotic-loaded cement, higher age, and higher BMI were associated with lower risk of further revision whereas a higher degree of surgeon experience was associated with higher risk.