Impact of comorbidity on the short- and medium-term risk of revision in total hip and knee arthroplasty

Postoperative delirium following total joint arthroplasty: epidemiology, risk factors, and associated complications

INTRODUCTION

Postoperative delirium (POD) is a feared complication following major surgery in elderly patients. Further investigation of the risk factors and consequences of POD following total joint arthroplasty is warranted.

METHODS

Patients who underwent total knee arthroplasty (TKA) or total hip arthroplasty (THA) were identified using PearlDiver. Patients were filtered into 2 cohorts based on the presence or absence of POD within 7 days of surgery. Epidemiological analyses were performed to examine trends in POD following TKA and THA by age group and year. Comparative analyses were performed on patient demographics and baseline cognitive status. After matching by age, sex, and comorbidities, electrolyte disturbances and 90-day postoperative complications were analysed.

RESULTS

Among 2,518,918 (99.7%) no POD and 7240 (0.3%) POD patients who underwent total knee or hip arthroplasty, mean age was 65.58 years, 60.2% were female, and mean CCI was 1.50 for the whole cohort. POD patients frequently had baseline cognitive impairment (P < 0.001). Incidence of POD decreased from 0.54% in 2010 to 0.10% in 2022 (P < 0.001) and increased with age (P < 0.001). POD patients had higher 90-day costs (TKA = $19,572 vs. $10,397, P < 0.001; THA = $18,496 vs. $9,877 P < 0.001). After matching, POD TKA patients had higher rates of hypernatraemia (6.1% vs 4.5%, P = 0.001) and POD THA patients had higher rates of hyponatraemia (26.5% vs 23.1%, P = 0.008). POD patients had higher rates of 90-day postoperative medical and surgical complications (P < 0.05) than no POD patients.

CONCLUSIONS

Nearly 0.3% of patients who underwent either TKA or THA between 2010 and 2022 developed transient delirium. POD was most common in elderly patients with baseline cognitive impairment undergoing revision surgery. POD patients had higher rates of 90-day postoperative surgical and joint-related complications. While POD rates have decreased, continued initiative to prevent POD in total joint arthroplasty patients is imperative.

Does interaction occur between risk factors for revision total knee arthroplasty?

INTRODUCTION

Several risk factors for revision TKA have previously been identified, but interactions between risk factors may occur and affect risk of revision. To our knowledge, such interactions have not been previously studied. As patients often exhibit multiple risk factors for revision, knowledge of these interactions can help improve risk stratification and patient education prior to TKA.

MATERIALS AND METHODS

The State Inpatient Databases (SID), part of the Healthcare Cost and Utilization Project (HCUP), were queried to identify patients who underwent TKA between January 1, 2006 and December 31, 2015. Risk factors for revision TKA were identified, and interactions between indication for TKA and other risk factors were analyzed.

RESULTS

Of 958,944 patients who underwent TKA, 33,550 (3.5%) underwent revision. Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA were significantly associated with revision (p < 0.05). Age was the strongest predictor (p  < 0.0001), with younger patients exhibiting higher revision risk. Risks associated with age were modified by an interaction with indication for TKA (p < 0.0001). There was no significant interaction between sex and indication for TKA (p = 0.535) or race and indication for TKA (p = 0.187).

CONCLUSIONS

Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA are significantly associated with revision TKA. Interaction occurs between age and indication.

Total Hip Arthroplasty Patients Who Have Ostomies Have an Increased Risk of Revisions for Periprosthetic Joint Infection, but Total Knee Arthroplasty Patients Do Not

BACKGROUND

Patient comorbidities can lead to worse outcomes and increase the risk of revisions after total hip arthroplasty (THA) and total knee arthroplasty (TKA). Sparse research is available on the effects of ostomies on postoperative outcomes. Our study aimed to assess whether patients who have ostomies, who underwent TKA or THA, have worse outcomes and increased rates of all-cause and periprosthetic joint infection (PJI)-related revisions.

METHODS

We performed a retrospective cohort study comparing the outcomes of THA and TKA patients who have and do not have a history of ostomy using the Statewide Planning and Research Cooperative System. Patient demographics, ostomy diagnosis, 3-month emergency department visits and readmissions, and revisions were collected. A total of 126,414 THA and 216,037 TKA cases were included. Log-rank testing and a Cox proportional hazards model were used to account for covariates.

RESULTS

In total, 463 THA patients (0.4%) had ostomies. They had a longer length of stay (4.0 versus 3.1 days, P < 0.001) and were less likely to be discharged home (55.3 versus 62.2%, P = 0.01). They had higher rates of PJI-related revisions (1.9 versus 0.9%, P = 0.02) and had increased odds of PJI-related revision (OR [odds ratio] = 2.2, P = 0.02). Of TKA patients, 619 patients (0.3%) had an ostomy. They had a longer length of stay (3.6 versus 3.3 days, P = 0.02) and was less likely to be discharged home (49.4 versus 52.4%, P = 0.16). However, there was no difference in the rate (1.8 versus 1.4%, P = 0.49) or odds (OR = 1.2, P = 0.53) of PJI-related revision.

CONCLUSIONS

THA, but not TKA, patients who have ostomies have an increased risk of PJI-related revisions. The proximity of the surgical incision to the ostomy site may play a role in the risk of PJI in THA patients.

The Financial Burden of Patient Comorbidities on Total Hip Arthroplasties-A Matched Cohort Analysis of High Comorbidity Burden and Non-High Comorbidity Burden Patients

BACKGROUND

The impact of increased patient comorbidities on the cost-effectiveness of total hip arthroplasty (THAs) is lacking. This study aimed to compare revenue, costs, and short-term (90 days) surgical outcomes between patients who have and do not have a high comorbidity burden (HCB).

METHODS

We retrospectively reviewed 14,949 patients who underwent an elective, unilateral THA between 2012 and 2021. Patients were stratified into HCB (Charlson Comorbidity Index ≥ 5 and American Society of Anesthesiology scores of 3 or 4) and non-HCB groups, and were further 1:1 propensity matched based on baseline characteristics. Perioperative data, revenue, costs, and contribution margins (CMs) of the inpatient episode were compared between groups. Also, 90-day readmissions and revisions were compared between groups. Of the 11,717 patients who had available financial data (n = 1,017 HCB, n = 10,700 non-HCB), 1,914 patients were included in the final matched analyses (957 per group).

RESULTS

Total (P < .001) and direct (P < .001) costs were significantly higher for HCB patients. Comparable revenue between cohorts (P = .083) resulted in a significantly decreased CM in the HCB patient group (P < .001). The HCB patients were less likely to be discharged home (P < .001) and had significantly higher 90-day readmission rates (P = .049).

CONCLUSIONS

Increased THA costs for HCB patients were not matched by increased revenue, resulting in decreased CM. Higher rates of nonhome discharge and readmissions in the HCB population add to the additional financial burden. Adjustments to the current reimbursement models should better account for the increased financial burden of HCB patients undergoing THA and ensure access to care for all patient populations.

LEVEL OF EVIDENCE

III.

Comparative analysis of femoral bone loss: uncemented vs. cemented aseptic stem loosening in first-time revision surgery-a retrospective evaluation of 215 patients

INTRODUCTION

The integrity of the femoral bone is crucial when considering reconstructive options for the first-time revision of a total hip arthroplasty (THA). Aseptic loosening of primary stems, whether cemented or uncemented, significantly affects the volume and quality of resultant femoral bone loss. This study evaluates the impact of the initial fixation method on femoral bone defect patterns by comparing the extent of bone loss.

MATERIALS AND METHODS

A retrospective cohort of 215 patients with either cemented or uncemented stems, indicated for aseptic stem loosening, and undergoing first-time stem revision from 2010 to 2022 at our institution was analyzed. Femoral bone loss extent at first-time revision was preoperatively gauged using radiographs and categorized by the Paprosky classification. Survival probabilities pre-first-time revision for both stem types were calculated using Kaplan-Meier methods. Hazard ratios were applied to compare the risk of initial revision for uncemented versus cemented stems within the first and subsequent 2nd to 10th years post-primary implantation.

RESULTS

Cemented stems were associated with a higher occurrence of significant bone defects of type 3a (23.53% vs. 14.02%, p = .108), 3b (39.22% vs. 1.22%, p < .001), and 4 (3.92% vs. 0.00%) compared to uncemented stems. Conversely, smaller defects of type 1 and 2 were more prevalent in uncemented stem loosening (84.76% vs. 33.33%, p < .001). Notably, cemented stems exhibited a significantly prolonged revision-free period over the complete decade following primary insertion (p < .001). The unadjusted risk of first-time revision due to stem loosening showed a tendency to an increase in uncemented stems within the initial postoperative year (HR 5.55, 95% CI 0.74; 41.67, p = .096), and an adjusted risk of 2.1 (95% CI 0.26; 16.53, p = .488). However, these differences did not reach statistical significance. In the subsequent 2nd-10th years, the risk was lower compared to cemented stems (HR 2.35, 95% CI 1.39; 3.99, p = .002).

CONCLUSIONS

Uncemented primary stems necessitating first-time revision due to aseptic loosening demonstrated notably smaller femoral bone defects in comparison to primary cemented stems.

Efficacy of surgical intervention over conservative management in intertrochanteric fractures among nonagenarians and centenarians: a prospective cohort study

BACKGROUND

Optimal treatment strategy for nonagenarians and centenarians with hip fractures (NCHF) remained unknown. The authors aimed to compare the outcomes of surgical and conservative management in NCHF.

METHODS

A prospective cohort study was conducted based on CPMHF database with NCHF patients hospitalized during 2014-2020. Comorbidities were evaluated by mECM score and restricted cubic spline was utilized to visually assess the dose-effect relationship between the mECM and outcomes. Propensity score matching was performed to balance baseline characteristics between nonsurgical and surgical groups. Multivariate logistic regression, Cox proportional hazard analysis, and survival analysis were employed for unfavorable outcomes (UFO) evaluation. Competing risk of death were analyzed based on Fine and Gray's hazard model and then constructed nomogram models for predicting survival rates. Subgroup analyses were used to determine potential population heterogeneity and sensitivity analyses were performed to test robustness of the results.

RESULTS

The authors found increasing trends for UFO with the increase in the mECM score, and that high mECM score (HMS, ≥3) was independently associated with a 2.42-fold (95% CI: 2.07-3.54; P =0.024) increased risk of UFO, which remained significant after considering the competing role of death and were more pronounced in nonsurgical treatment, women, no insurance, and patients with spouse (all P for interaction <0.05). Surgical intervention was identified to be significant protective factors for UFO (RR, 0.59; 95% CI: 0.46-0.75; P <0.001) and severe complications (RR, 0.63; 95% CI: 0.41-0.96; P =0.033) after propensity score matching, as well as survival (HR, 0.40, 95% CI: 0.28-0.58; P <0.001), which remained significant after considering the competing role of death and in all sensitivity analyses and were more pronounced in HMS participants ( P for interaction=0.006). Subgroup analyses revealed surgical patients with HMS had a significantly higher UFO rate (excluding death, P <0.001) while nonsurgical patients with HMS had higher mortality rate as compared to the others ( P =0.005).

CONCLUSION

Surgical treatment for NCHF yields better outcomes compared to conservative treatment.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

Multimorbidity measured with Charlson Comorbidity Index is not associated with clinically relevant risk of revision after primary total hip arthroplasty: a population-based cohort study on 98,647 patients from the Danish Hip Arthroplasty Register

BACKGROUND AND PURPOSE

Evidence for guiding healthcare professionals on the risks of total hip arthroplasty (THA) in multimorbid patients is sparse. We aimed to examine the association between multimorbidity and the risk of revision due to any cause and specific causes after primary THA due to osteoarthritis.

PATIENTS AND METHODS

We identified 98,647 THA patients and subsequent revisions in the Danish Hip Arthroplasty Register from 1995 to 2018. Multimorbidity was measured with the Charlson Comorbidity Index (CCI). Using the CCI (low, medium, high), we calculated the cumulative incidence function (CIF) of first revision up to 10 years after THA. Adjusted cause-specific hazard ratios (aHRs) were estimated using Cox regressions. All estimates are presented with 95% confidence intervals (CI).

RESULTS

Overall, the prevalence of patients with low, medium, and high CCI was 70%, 24%, and 6%. The CIF of any revision within 10 years was 6.5% (CI 6.2-6.7) in low and 6.5% (CI 5.8-7.3) in high CCI, with an aHR of 1.4 (CI 1.2-1.6) for patients with high compared with low CCI. The corresponding aHRs for cause-specific revision were 1.3 (CI 1.0-1.6) for aseptic loosening within 10 years, 1.2 (CI 0.9-1.6) for infection, and 1.7 (CI 1.3-2.2) for dislocation, both within 2 years.

CONCLUSION

Multimorbidity is associated with a minor but not clinically relevant increased risk of revision up to 10 years after primary THA.

Can extant comorbidity indices identify patients who experience poor outcomes following total joint arthroplasty?

INTRODUCTION

It is uncertain if generic comorbidity indices commonly used in orthopedics accurately predict outcomes after total hip (THA) or knee arthroplasty (TKA). The purpose of this study was to determine the predictive ability of such comorbidity indices for: (1) 30-day mortality; (2) 30-day rate of major and minor complications; (3) discharge disposition; and (4) extended length of stay (LOS).

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was retrospectively reviewed for all patients who underwent elective THA (n = 202,488) or TKA (n = 230,823) from 2011 to 2019. The American Society of Anesthesiologists (ASA) physical status classification system score, modified Charlson Comorbidity Index (mCCI), Elixhauser Comorbidity Measure (ECM), and 5-Factor Modified Frailty Index (mFI-5) were calculated for each patient. Logistic regression models predicting 30-day mortality, discharge disposition, LOS greater than 1 day, and 30-day major and minor complications were fit for each index.

RESULTS

The ASA classification (C-statistic = 0.773 for THA and TKA) and mCCI (THA: c-statistic = 0.781; TKA: C-statistic = 0.771) were good models for predicting 30-day mortality. However, ASA and mCCI were not predictive of major and minor complications, discharge disposition, or LOS. The ECM and mFI-5 did not reliably predict any outcomes of interest.

CONCLUSION

ASA and mCCI are good models for predicting 30-day mortality after THA and TKA. However, similar to ECM and mFI-5, these generic comorbidity risk-assessment tools do not adequately predict 30-day postoperative outcomes or in-hospital metrics. This highlights the need for an updated, data-driven approach for standardized comorbidity reporting and risk assessment in arthroplasty.

Trajectories of Pain and Function Outcomes up to 5 to 8 Years Following Total Knee Arthroplasty

BACKGROUND

There appears to be substantial variability in outcomes > 2 years following total knee arthroplasty (TKA) that is masked by whole group analyses. The goal of the study was to identify trajectories of pain and function outcomes up to 5 to 8 years post-TKA and to identify baseline factors that are associated with different trajectories of recovery.

METHODS

Baseline, 6-month, and 12-month pain and function data were collected in a previous study investigating predictors of outcome following primary TKA (n = 286), along with a variety of baseline predictor variables. The present study obtained pain and function data at 5 to 8 years following TKA in the same cohort (n = 201). Latent class linear mixed models were used to identify different classes of pain and functional trajectories over time. The extent to which differences across latent classes were explained by baseline predictor variables was determined.

RESULTS

Three classes of pain and two classes of function trajectory were identified. While most patients (84% to 93%) followed a trajectory that showed an initial rapid gain following surgery that was sustained through 5 to 8 years, both pain and function included at least one trajectory class that showed a meaningful change after 12 months. No predictor variables were significantly associated with either the pain or function classes.

CONCLUSIONS

Most patients follow a traditional trajectory of recovery in knee pain and function over 5 to 8 years. However, alternative trajectories are observed in an important minority of patients such that knee pain and function at 12 months after surgery does not always reflect outcomes at 5 to 8 years.

Predicting Hospital Readmissions After Total Shoulder Arthroplasty Within a Bundled Payment Cohort

INTRODUCTION

Given the rising demand for shoulder arthroplasty, understanding risk factors associated with unplanned hospital readmission is imperative. No study to date has examined the influence of patient and hospital-specific factors as a predictive model for 90-day readmissions within a bundled payment cohort after primary shoulder arthroplasty. The purpose of this study was to determine predictive factors for 90-day readmissions after primary shoulder arthroplasty within a bundled payment cohort.

METHODS

After obtaining IRB approval, a retrospective review of a consecutive series of Medicare patients undergoing primary shoulder arthroplasty from 2014 to 2020 at a single academic institution was conducted. Patient demographic data, surgical variables, medical comorbidity profiles, medical risk scores, and social risk scores were collected. Postoperative variables included length of hospital stay, discharge location, and 90-day readmissions. Multivariate analysis was conducted to determine the independent risk factors of 90-day readmission.

RESULTS

Overall, 3.6% of primary shoulder arthroplasty patients (127/3,523) were readmitted within 90 days. Readmitted patients had a longer hospital course (1.75 versus 1.45 P = 0.006), higher comorbidity profile (4.64 versus 4.24 P = 0.001), higher social risk score (7.96 versus 6.9 P = 0.008), and higher medical risk score (10.1 versus 6.96 P < 0.001) and were more likely to require a home health aide or be discharged to an inpatient rehab facility or skilled nursing facility ( P = 0.002). Following multivariate analysis, an elevated medical risk score was associated with an increased risk of readmission (odds ratio = 1.05, P < 0.001).

DISCUSSION

This study demonstrates medical risk scores to be an independent risk factor of increased risk of 90-day hospital readmissions after primary shoulder arthroplasty within a bundled payment patient population. Additional incorporation of medical risk scores may be a beneficial adjunct in preoperative prediction for readmission and the potentially higher episode-of-care costs.

LEVEL OF EVIDENCE

Level III, retrospective cohort.

A Prospective, Longitudinal Study of the Influence of Obesity on Total Knee Arthroplasty Revision Rate: Results from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

The aim of this study was to investigate the relationship of obesity with all-cause revision and revision for infection, loosening, instability, and pain after total knee arthroplasty (TKA) performed in Australia.

METHODS

Data for patients undergoing primary TKA for osteoarthritis from January 1, 2015, to December 31, 2020, were obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). The rates of all-cause revision and revision for infection, loosening, instability, and pain were compared for non-obese patients (body mass index [BMI], 18.50 to 29.99 kg/m 2 ), class-I and II obese patients (BMI, 30.00 to 39.99 kg/m 2 ), and class-III obese patients (BMI, ≥40.00 kg/m 2 ). The results were adjusted for age, sex, tibial fixation, prosthesis stability, patellar component usage, and computer navigation usage.

RESULTS

During the study period, 141,673 patients underwent primary TKA for osteoarthritis in Australia; of these patients, 48.0% were class-I or II obese, and 10.6% were class-III obese. The mean age was 68.2 years, and 54.7% of patients were female. The mean follow-up period was 2.8 years. Of the 2,655 revision procedures identified, the reasons for the procedures included infection in 39.7%, loosening in 14.8%, instability in 12.0%, and pain in 6.1%. Class-I and II obese patients had a higher risk of all-cause revision (hazard ratio [HR], 1.12 [95% confidence interval (CI), 1.03 to 1.22]; p = 0.007) and revision for infection (HR, 1.25 [95% CI, 1.10 to 1.43]; p = 0.001) than non-obese patients. Class-III obese patients had a higher risk of all-cause revision after 1 year (HR, 1.30 [95% CI, 1.14 to 1.52]; p < 0.001), revision for infection after 3 months (HR, 1.72 [95% CI, 1.33 to 2.17]; p < 0.001), and revision for loosening (HR, 1.39 [95% CI, 1.00 to 1.89]; p = 0.047) than non-obese patients. The risks of revision for instability and pain were similar among groups.

CONCLUSIONS

Obese patients with knee osteoarthritis should be counseled with regard to the increased risks associated with TKA, so they can make informed decisions about their health care. Health services and policymakers need to address the issue of obesity at a population level.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Surgeon and Facility Volumes Are Associated With Social Disparities and Post-Operative Complications After Total Hip Arthroplasty

BACKGROUND

The purpose of this study is to further characterize the volume dependence of facilities and surgeons on morbidity and mortality after total hip arthroplasty (THA).

METHODS

Adults who underwent THA from 2009 to 2014 were identified using International Classification of Diseases, Ninth Revision, Clinical Modification and Procedural codes in the New York Statewide Planning and Research Cooperative System database. Complication rates were compared across surgeon and facility volumes using multivariable Cox proportional hazards regression controlling for factors such as the Social Deprivation Index. Surgeon and facility volumes were compared between the low and high volume using cutoffs established by prior research.

RESULTS

In total, 99,832 patients were included. Low volume facilities had higher rates of readmission, urinary tract infection (UTI), acute renal failure, pneumonia, surgical site infection (SSI), cellulitis, wound complications, deep vein thrombosis (DVT), in-hospital mortality, and revision. Low volume surgeons had higher rates of readmission, UTI, acute renal failure, pneumonia, SSI, acute respiratory failure, pulmonary embolism, cellulitis, wound complications, in-hospital mortality, cardiorespiratory arrest, DVT, and revision. African Americans, Hispanics, and those with federal insurance had increased rates of readmission. Those with ≥1 Charlson comorbidities or from areas of higher social deprivation had increased incidence of treatment by low volume surgeons and facilities.

CONCLUSION

Both low volume facilities and surgeons performing primary THA have higher rates of readmission, UTI, acute renal failure, pneumonia, SSI, cellulitis, wound complications, DVT, in-hospital mortality, and revision. Demographic disparities exist between who is treated at low vs high volume surgeons and facilities placing those groups at higher risks for complications.

A Retrospective Review of Relative Value Units in Revision Total Knee Arthroplasty: A Dichotomy Between Surgical Complexity and Reimbursement

BACKGROUND

Revision total knee arthroplasties (TKA) are costly, time-intensive, and technically demanding procedures. There are concerns regarding the valuation of Current Procedural Terminology (CPT) codes and the assigned relative value units (RVU) as a potential disincentive to perform revision TKAs. This study evaluated the labor and time investment for each component-specific revision and assessed the disparities between procedural value billed and reimbursement.

METHODS

A retrospective review of 154 primary and revision TKA cases were thoroughly vetted using operative notes and internal billing data. Revision TKAs were stratified by single femoral component, single tibial component, polyethylene liner only, all-component, and spacer placement for prosthetic infection. Operative time, RVUs billed, total charges, deductions, and reimbursements were recorded. Mann-Whitney U tests compared final reimbursement per minute and per RVU between revision and primary TKAs.

RESULTS

There were 28 primary TKAs, 11 femoral component revisions, 25 tibial component revisions, 25 liner exchanges, 37 all-component revisions, and 28 spacer placements. Revisions involving the tibial component, all-components, and placement of spacers were reimbursed less dollars per minute than primary TKAs (P < .05). Controlling for RVUs, liner exchanges and all-component revisions had fewer dollars per RVU than primary TKAs (P < .05).

CONCLUSION

As revision complexity increases, physicians face less reimbursement per minute and per RVU. With reductions set by CMS and private insurers, revisions may be financially unfavorable and lead to restrictions and access to care problems. Our data supports the need for reevaluating RVU allocation amongst revision procedures with potential updates to the CPT coding system.

Prediction of complications and surgery duration in primary TKA with high accuracy using machine learning with arthroplasty-specific data

PURPOSE

The number of primary total knee arthroplasties (TKA) is expected to rise constantly. For patients and healthcare providers, the early identification of risk factors therefore becomes increasingly fundamental in the context of precision medicine. Others have already investigated the detection of risk factors by conducting literature reviews and applying conventional statistical methods. Since the prediction of events has been moderately accurate, a more comprehensive approach is needed. Machine learning (ML) algorithms have had ample success in many disciplines. However, these methods have not yet had a significant impact in orthopaedic research. The selection of a data source as well as the inclusion of relevant parameters is of utmost importance in this context. In this study, a standardized approach for ML in TKA to predict complications during surgery and an irregular surgery duration using data from two German arthroplasty-specific registries was evaluated.

METHODS

The dataset is based on two initiatives of the German Society for Orthopaedics and Orthopaedic Surgery. A problem statement and initial parameters were defined. After screening, cleaning and preparation of these datasets, 864 cases of primary TKA (2016-2019) were gathered. The XGBoost algorithm was chosen and applied with a hyperparameter search, a cross validation and a loss weighting to cope with class imbalance. For final evaluation, several metrics (accuracy, sensitivity, specificity, AUC) were calculated.

RESULTS

An accuracy of 92.0%, sensitivity of 34.8%, specificity of 95.8%, and AUC of 78.0% were achieved for predicting complications in primary TKA and 93.4%, 74.0%, 96.3%, and 91.6% for predicting irregular surgery duration, respectively. While traditional statistics (correlation coefficient) could not find any relevant correlation between any two parameters, the feature importance revealed several non-linear outcomes.

CONCLUSION

In this study, a feasible ML model to predict outcomes of primary TKA with very promising results was built. Complex correlations between parameters were detected, which could not be recognized by conventional statistical analysis. Arthroplasty-specific data were identified as relevant by the ML model and should be included in future clinical applications. Furthermore, an interdisciplinary interpretation as well as evaluation of the results by a data scientist and an orthopaedic surgeon are of paramount importance.

LEVEL OF EVIDENCE

Level IV.

The effect of patient and prosthesis factors on revision rates after total knee replacement using a multi-registry meta-analytic approach

BACKGROUND AND PURPOSE

Characteristics of patients receiving total knee arthroplasty (TKA) and prostheses used vary between regions and change with time. How these practice variations influence revision remains unclear. We combined registry data for better understanding of the impact of variation, which could potentially improve revision rates.

PATIENTS AND METHODS

We used data from 2003 to 2019 for primary TKA from arthroplasty registries of Sweden (SKAR), Australia (AOANJRR), and Kaiser Permanente (KPJRR). We included 1,072,924 TKA procedures for osteoarthritis. Factors studied included age, sex, ASA class, BMI category, prosthesis constraint, fixation, bearing mobility, patellar resurfacing, and polyethylene type. Cumulative percentage revision (CPR) was calculated using Kaplan-Meier estimates, and unadjusted Cox hazard ratios were used for comparisons. Random-effects generic inverse-variance meta-analytic methods were used to determine summary effects.

RESULTS

We found similarities in age and sex, but between-registry differences occurred in the other 7 factors studied. Patients from Sweden had lower BMI and ASA scores compared with other registries. Use of cement fixation was similar in the SKAR and KPJRR, but there were marked differences in patellar resurfacing and posterior stabilized component use. Meta-analysis results regarding survivorship favored patients aged ≥ 65 years and minimally stabilized components. There were inconsistent results with time for sex, fixation, and bearing mobility, and no differences for the patellar resurfacing or polyethylene type comparisons.

INTERPRETATION

Marked practice variation was found. Use of minimally stabilized and possibly also cemented and fixed bearing prostheses is supported.