Does body mass index affect the rate of adverse outcomes in total hip and knee arthroplasty? A retrospective review of a total joint replacement database

Sleep Apnea is Not an Obstacle for Outpatient Hip and Knee Arthroplasty

BACKGROUND

Up to 25% of patients requiring hip or knee arthroplasty have sleep apnea (SA), and these patients have historically been excluded from outpatient programs. The objectives of this study were to evaluate same-day discharge failure as well as 30-day complications, readmissions, and unexpected visits.

METHODS

A retrospective case-control study comparing patients who have and do not have SA matched for age, sex and arthroplasty type (total hip arthroplasty, total knee arthroplasty, unicompartimental knee arthroplasty) who underwent primary outpatient surgery between February 2019 and December 2022 in 2 academic hospitals was conducted. Cases with mild SA, moderate SA with a body mass index (BMI) <35, and SA of all severity treated by continuous positive airway pressure machines were eligible. There were 156 patients included (78 cases). Complications were assessed according to the Clavien-Dindo Classification and the Comprehensive Complication Index. Continuous variables were evaluated by Student's T or Mann-Whitney tests, while categorical data were analyzed by Chi-square or Fisher tests. Univariate analyses were performed to determine discharge failure risk factors.

RESULTS

There were 6 cases (7.7%) and 5 controls (6.4%) who failed to be discharged on surgery day (P = .754), with postoperative hypoxemia (6, [3.8%]) and apnea periods (3, [1.9%]) being the most common causes. Higher BMI (odds ratio = 1.19, P = .013) and general anesthesia (odds ratio = 11.97, P = .004) were found to be risk factors for discharge failure. No difference was observed on 30-day readmissions (P = .497), unexpected visits (P = 1.000), and complications on the Clavien-Dindo Classification (P > .269) and Comprehensive Complication Index (P > .334) scales.

CONCLUSIONS

Selected patients who have SA can safely undergo outpatient hip or knee arthroplasty. Higher BMI and general anesthesia increased the odds of same-day discharge failure.

LEVEL OF EVIDENCE

Level III, Case-control Study.

A Comparison of the Periprosthetic Fracture Rate of Cemented and Cementless Total Knee Arthroplasties: An Analysis of Data From the National Joint Registry

BACKGROUND

Periprosthetic fractures are serious complications of knee arthroplasty often requiring complex surgery. There is concern of increased periprosthetic fracture risk with cementless components given the reliance on interference fit for primary stability. It is unknown how the periprosthetic fracture risk compares between cemented and cementless total knee arthroplasties (TKAs).

METHODS

A total of 22,477 cemented and 22,477 cementless TKAs from the National Joint Registry and Hospital Episodes Statistics database were propensity score matched on patient and surgical factors. Cumulative periprosthetic fracture rates were calculated using Kaplan-Meier analyses and compared with Cox regressions. Subgroup analyses were performed in different age, body mass index, and sex groups.

RESULTS

The 3-month fracture rate in the cemented and cementless TKA groups were 0.02% and 0.04%, respectively. At 10 years, the cumulative fracture rate after cemented TKA was 1.2%, and after cementless was 1.4%. During the study period, there were no significant differences in fracture rates between cemented and cementless TKAs with a hazards ratio 1.14 (confidence interval 0.94 to 1.37, P = .20) at 10 years postoperatively. There were no significant differences in fracture rates between fixation types on subgroup analyses of sex, body mass index, and age groups. Female sex was a risk factor for fracture in both cemented (odds ratio 2.35, P < .001) and cementless TKAs (odds ratio 2.97, P < .001).

CONCLUSIONS

The periprosthetic fracture rates following cemented and cementless TKA surgery are low being approximately 1.2% and 1.4%, respectively at 10 years. There were no significant differences in periprosthetic fracture rates requiring readmission between cemented and cementless TKAs.

LEVEL OF EVIDENCE

III.

How Has the Total Hip Arthroplasty Patient Population Changed? A Ten-Year Analysis of Total Hip Arthroplasty Patients From 2013 to 2022: A Retrospective, Single-Center Study

BACKGROUND

Over the past decades, utilization of total hip arthroplasty (THA) has steadily increased. Understanding the demographic trends of THA patients can assist in projecting access to care. This study sought to assess the temporal trends in THA patient baseline characteristics and socioeconomic factors.

METHODS

We retrospectively analyzed 16,296 patients who underwent primary elective THA from January 1, 2013, to December 31, 2022. Demographic data, including age, sex, race, body mass index (BMI), Charlson comorbidity index, insurance, and socioeconomic status, as determined by median income by patients' zip code, were collected. The trends of these data were analyzed using the Mann-Kendall test.

RESULTS

Over the past decade at our institution, patient age (2013: 62.1 years to 2022: 65.1 years, P = .001), BMI (2013: 29.0 to 2022: 29.5, P = .020), and mean Charlson comorbidity index (2013: 2.4 to 2022: 3.1, P = .001) increased. The proportion of Medicare patients increased from 48.4% in 2013 to 54.9% in 2022 (P = .001). The proportion of African American patients among the THA population increased from 11.3% in 2013 to 13.0% in 2022 (P = .012). Over this period, 90-day readmission and 1-year revision rates did not significantly change (2013: 4.8 and 3.0% to 2022: 3.4 and 1.4%, P = .107 and P = .136, respectively). The proportion of operations using robotic devices also significantly increased (2013: 0% to 2022: 19.1%; P < .001).

CONCLUSIONS

In the past decade, the average age, BMI, and comorbidity burden of THA patients have significantly increased, suggesting improved access to care for these populations. Similarly, there have been improvements in access to care for African American patients. Along with these changes in patient demographics, we found no change in 90-day readmission or 1-year revision rates. Continued characterization of the THA patient population is vital to understanding this demographic shift and educating future strategies and improvements in patient care.

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.

Severe obesity in total knee arthroplasty occurs in younger patients with a greater healthcare burden and complication rate

BACKGROUND

Knee osteoarthritis in the presence of severe obesity (BMI ≥ 40) is becoming an increasing presentation to healthcare services. When progressing to arthroplasty, this group is known to have higher complication rates.

METHOD

A retrospective cohort study at a tertiary referral centre (UK) with all sequential patients undergoing TKA between 2019 and 2020 included following identification from the UK National Joint Registry. Patients were divided by BMI < 40 and BMI ≥ 40 (86, 16.3%). Analysis of BMI with pre-operative parameters including age, ASA, and blood parameters was performed. Primary outcome was re-operation rate. Secondary outcomes included length of stay, complications, and re-admission.

RESULTS

Five hundred and twenty-eight sequential TKA patients were included. The BMI < 40 group (442 patients, 83.7%) were mean 5.4 years younger (p < 0.001), had a higher ASA grade (p < 0.001) lower albumin (p < 0.001) and higher HbA1c (p < 0.001) than the BMI ≥ 40 group (86 patients, 16.3%). The BMI ≥ 40 group had a higher rate of re-operation (8% vs 2%, p = 0.012), and longer length of stay (mean 1.2 days longer p < 0.001), most commonly due to wound discharge, which alongside dehiscence was significantly higher (11.6% vs 4.3% p = 0.02). Overall, re-admission rates were also higher (18.6% vs 6.1% p = 0.06) with wound dehiscence, superficial infection, and deep infection the most common causes.

CONCLUSIONS

Those patients undergoing TKA with a BMI ≥ 40 are younger and have higher reoperation rates, greater length of stay, higher re-admission rates and more postoperative complications, providing a target for the development of pre-operative optimisation programmes.

Body Mass Index as a Predictor for Postoperative Complications Following Carpometacarpal Arthroplasty

Purpose

Carpometacarpal (CMC) arthroplasty is an effective surgical treatment to relieve pain and improve function for osteoarthritis of the CMC joint. The association between body mass index (BMI) and postoperative complications has been studied for other orthopedic procedures, including total knee arthroplasty, total hip arthroplasty, and total shoulder arthroplasty. However, BMI has not been studied as a risk factor for postoperative complications following CMC arthroplasty. The purpose of this study was to determine the postoperative complications associated with different categories of BMI following CMC arthroplasty. We hypothesized that increasing BMI is associated with more severe complications.

Methods

The American College of Surgeons National Surgical Quality Improvement Program database was queried for all patients who underwent CMC arthroplasty between 2015 and 2020. Patient demographics, comorbidities, surgical characteristics, and 30-day postoperative complication data were collected. Patients were stratified into cohorts based on BMI as follows: underweight (BMI < 18.5 kg/m2), normal/reference (18.5 kg/m2 ≤ BMI < 30.0 kg/m2), obese (30.0 kg/m2 ≤ BMI < 35.0 kg/m2), severely obese (35.0 kg/m2 ≤ BMI < 40.0 kg/m2), and morbidly obese (BMI ≥ 40.0 kg/m2). Multivariate logistic regression was used to identify postoperative complications associated with each cohort.

Results

In total, 6,432 patients were included in this study: 3,622 (56.3%) patients were included in the normal/reference cohort, 77 (1.2%) patients were included in the underweight cohort, 1,479 (23.0%) patients were included in the obese cohort, 718 (11.2%) patients were included in the severely obese cohort, and 536 (8.3%) patients were included in the morbidly obese cohort. The obese cohort was independently associated with a higher rate of superficial incisional surgical-site infection (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.00-4.44; P = .050). The morbidly obese cohort was independently associated with readmission (OR, 3.35; 95% CI, 1.15-9.74; P = .026) and reoperation (OR, 3.40; 95% CI, 1.04-1.11; P = .043).

Conclusions

Morbid obesity is a clinically significant predictor for readmission and reoperation within 30 days following CMC arthroplasty. Obesity is a clinically significant predictor for superficial incisional surgical-site infection within 30 days following CMC arthroplasty.

Clinical relevance

A better understanding of BMI as a risk factor for postoperative complications may allow surgeons to improve preoperative risk stratification and patient counseling.

Type of study/level of evidence

Prognostic III.

[Results and complications of knee arthroplasty in patients with obesity]

Introduction

In México, many patients undergoing total knee arthroplasty (TKA) are obese, which has medical and financial consequences. The functional outcomes and the incidence of complications of these patients remain uncertain due to the inconsistency between studies.

Objective

To determine the association between obesity, complications and functional results of patients undergoing TKA.

Material and methods

Descriptive, cross-sectional, prospective, observational, cohort study in which patients who underwent TKA between September 1, 2021, and August 30, 2022, were studied. Patients were divided by their body mass index (BMI) in < 30kg/m2 and > 30kg/m2 and their demographic characteristics, Oxford Knee Score (OKS), and incidence of complications were compared.

Results

Out of the 102 patients, 59 presented a BMI < 30 kg/m2 and 43 a BMI > 30 kg/m2. No difference was found in their postoperative OKS (p = 0.12) and delta OKS (p = 0.07). A significant increase in trans-surgical (p = 0.02) and post-surgical (p = 0.04) complications was found in the group with BMI > 30 kg/m2, presenting a risk 5.03 times higher.

Conclusion

A BMI > 30kg/m2 does not affect the functional results after a TKA; however, it is associated with a risk 5.03 times higher of suffering complications during and after surgical intervention.

The Association of Total Knee Arthroplasty With Weight Loss in the Look AHEAD (Action for Health in Diabetes) Clinical Trial

BACKGROUND

Patients who have obesity seldom lose weight after total knee arthroplasty (TKA). The Look AHEAD (Action for Health in Diabetes) trial randomized patients with type 2 diabetes who were overweight or had obesity to a 10-year intensive lifestyle intervention (ILI) or diabetes support and education (DSE).

METHODS

Of the total 5,145 participants enrolled who had a median 14-year follow-up, a subset of 4,624 met inclusion criteria. The ILI aimed at achieving and maintaining a 7% weight loss and included weekly counseling the first 6 months, with decreasing frequency thereafter. This secondary analysis was undertaken to determine what effects a TKA had on patients participating in a known successful weight loss program and specifically if there was a negative impact on weight loss or their Physical Component Score.

RESULTS

The analysis suggests that the ILI remained effective for maintaining or losing weight after TKA. Participants in ILI had significantly greater percent weight loss than those in DSE both before and after TKA (ILI-DSE before TKA: -3.6% (-5.0, -2.3); after TKA: -3.7% (-4.1, -3.3); both P < .0001). When comparing percent weight loss before to after TKA, there was no significant difference within either the DSE or ILI group (least square means ± standard error ILI: -0.36% ± 0.3, P = .21; DSE: -0.41% ± 0.29, P = .16). Physical Component Scores improved after TKA (P < .001), but no difference was found between TKA ILI and DSE groups before or after surgery.

CONCLUSION

Participants who had a TKA did not have an altered ability to adhere to intervention goals to maintain weight loss or obtain further weight loss. The data suggest patients who have obesity can lose weight after TKA on a weight loss program.

Disparities in Elective and Nonelective Total Hip Arthroplasty

BACKGROUND

Prior studies have shown disparities in utilization of primary and revision total hip arthroplasty (THA). However, little is known about patient population differences associated with elective and nonelective surgery. Therefore, the aim of this study was to explore factors that influence primary utilization and revision risk of THA based on surgery indication.

METHODS

Data were obtained from 7,543 patients who had a primary THA from 2014 to 2020 in a database, which consists of multiple health partner systems in Louisiana and Texas. Of these patients, 602 patients (8%) underwent nonelective THA. THA was classified as "elective" or "nonelective" if the patient had a diagnosis of hip osteoarthritis or femoral neck fracture, respectively.

RESULTS

After multivariable logistic regression, nonelective THA was associated with alcohol dependence, lower body mass index (BMI), women, and increased age and number of comorbid conditions. No racial or ethnic differences were observed for the utilization of primary THA. Of the 262 patients who underwent revision surgery, patients who underwent THA for nonelective etiologies had an increased odds of revision within 3 years of primary THA (odds ratio (OR) = 1.66, 95% Confidence Interval (CI) = 1.06-2.58, P-value = .025). After multivariable logistic regression, patients who had tobacco usage (adjusted odds ratio (aOR) = 1.36, 95% CI = 1.04-1.78, P-value = .024), alcohol dependence (aOR = 2.46, 95% CI = 1.45-4.15, P-value = .001), and public insurance (OR = 2.08, 95% CI = 1.18-3.70, P-value = .026) had an increased risk of reoperation.

CONCLUSION

Demographic and social factors impact the utilization of elective and nonelective primary THA and subsequent revision surgery. Orthopaedic surgeons should focus on preoperative counseling for tobacco and alcohol cessation as these are modifiable risk factors to directly decrease reoperation risk.

Impact of being underweight on peri-operative and post-operative outcomes of total knee or hip arthroplasty: A meta-analysis

BACKGROUND

Many systematic reviews have focused on assessing the effect of body mass index (BMI) on the outcomes and complications associated with total hip arthroplasty (THA) and total knee arthroplasty (TKA), but primarily dealt with obesity compared to normal weight (NW). None of these reviews attempted to assess the effect of low BMI or underweight (UW) compared to NW in patients undergoing THA or TKA.

AIM

This review aims to compare specific operative outcomes such as operation duration, length of hospital stay, and post-operative complications including mortality, infections, deep vein thrombosis, etc. along with re-hospitalization and reoperation rates between UW and NW patients undergoing THA, TKA or both.

METHODS

An electronic search was performed in PubMed, Scopus, Excerpta Medica database (EMBASE), Web of Science (WoS), and Cochrane Central Register of Controlled Trials (CENTRAL) along with a manual search. The quality of the studies was assessed using the Newcastle-Ottawa scale for cohort studies. The data were subjected to both qualitative and quantitative analysis.

RESULTS

Thirteen retrospective and five prospective cohort studies were included. The quality of included studies was assessed to be good to fair. The length of hospital stay after TKA or THA was found to be significantly higher for UW patients when compared to NW patients, with a mean difference: 0.39 95%CI: [0.06, 0.72], P = 0.02 (in days). Studies presenting both THA and TKA together as total joint arthroplasty showed an increased incidence of mortality in patients treated with THA or TKA alone, Odds ratio: 4.18 95%CI: [2.88, 6.07]. A higher incidence of post-operative complications was also observed in UW patients undergoing THA.

CONCLUSION

UW patients undergoing THA or TKA had a higher incidence of post-operative complications and were associated with a higher readmission rate. Moreover, UW patients were associated with an increased incidence of mortality in the studies that reported THA and TKA together.

Clinical Outcomes of Total Hip Arthroplasty With the Anterolateral Modified Watson-Jones Approach for Displaced Femoral Neck Fractures

Objective

In recent years, many studies have reported good results with total hip arthroplasty (THA) for displaced femoral neck fractures (FNFs). However, no study has reported the clinical outcomes of the anterolateral modified Watson–Jones THA (MWJ-THA) for displaced FNFs. This study aimed to investigate the clinical results of THA for displaced FNFs at our hospital and to discuss the advantages of MWJ-THA over THA with other approaches for displaced FNFs.

Methods

Forty-three patients who underwent MWJ-THA for displaced FNFs were included in this study. Patient characteristics, preinjury walking ability, activities of daily living, implants used, walking ability (at 1, 3, and 6 months after surgery), cup placement angle, clinical hip score, surgical complications, revision surgery, and death within 1 year after surgery were investigated.

Results

The mean age of the 43 patients was 63.3 years, and the mean body mass index (kg/m²) was 21.1. Regarding the heads used, 28-mm heads were used in 4 patients, 32-mm heads were used in 32 patients, and 36-mm heads were used in 7 patients. The cups were placed in the Lewinnek safety zone (93.0%). Four patients had stem sinkage of a few millimeters. 6 months postoperatively, 38 patients walked unaided, and 4 patients walked with a cane. The Harris Hip Score averaged over 90 points at all time points. No postoperative dislocation was observed. Two patients died within 1 year postoperatively.

Conclusion

In this study, MWJ-THA was performed for displaced FNFs and resulted in no postoperative dislocations. Furthermore, more than 90% of the patients regained their preinjury walking ability at 6 months postoperatively. MWJ-THA has great dislocation control and is effective in treating displaced FNFs.

The impact of obesity on total knee arthroplasty outcomes: A retrospective matched cohort study

Background

Total Knee Arthroplasty (TKA) is a common orthopaedic surgery to treat advanced knee arthritis. Post-operative complications can be affected by obesity, defined as a body mass index of 30 kg/m2 or higher. We examine the rates of specific complications, revision rates, and costs of care following TKA and compare them between multifactor matched obese and non-obese patients. We hypothesize these outcomes will be worse in obese patients than in non-obese patients.

Methods

This retrospective study of the PearlDiver database queries for patients who underwent TKA under Current Procedural Terminology (CPT) and International Statistical Classification of Diseases (ICD-9) codes between January 2011 and January 2020. Patients were matched based on age, gender, and comorbidity indices, and various complications, revision rates, and costs were compared between the matched obese and non-obese patient groups.

Results

Obesity was associated with higher rates of surgical complications, such as wound complications, surgical site infections, need for revision, and higher total cost of care one year after TKA, and medical complications such as, acute kidney injury, deep vein thrombosis, urinary tract infection, and narcotics use, but significantly lower rates of anemia, arrhythmia, cardiac arrest, pneumonia, and transfusion. Obese patients also experienced significantly lower drug costs of care.

Conclusion

Outcomes were not definitively worse in obese patients when compared to matched non-obese patients. Nevertheless, understanding the complications that can arise following TKA will assist in educating patients about potential risks from surgery and guide surgeons in caring for their patients as obesity is predicted to continue increasing in prevalence. As such, future studies should examine underlying mechanisms that cause these complications to develop potential therapies.

The Impact of Obesity on Total Hip Arthroplasty Outcomes: A Retrospective Matched Cohort Study

Aim

Previous research has shown that obesity is associated with worse postoperative outcomes. We aim to determine how rates of specific complications after total hip arthroplasty (THA) align with obesity status. We hypothesize that obese patients would have higher rates of complications and cost and thus have worse outcomes than non-obese patients.

Methods

Data were collected from a large commercial insurance database between 2011 and 2020. Patients underwent a hip replacement under current procedural terminology (CPT) and International Statistical Classification of Diseases (ICD-9/ICD-10) codes. Obese (defined as having a BMI of 30 kg/m² or higher) and non-obese patients were matched on age, gender, Charlson Comorbidity Index (CCI), and Elixhauser Comorbidity Index (ECI). Standardized complications and costs in one year were compared using unequal variance t-tests.

Results

Under CPT codes, 61,462 obese (45% male) and 61,462 non-obese patients (45% male) underwent a hip replacement. Obese patients had significantly higher rates of surgical site infection (SSI) (OR=1.193, p=0.0001), deep vein thrombosis (DVT) (OR=1.275, p=0.001), wound complication (OR=1.736, p<0.0001), hematoma (OR=1.242, p=0.0001), pulmonary embolism (OR=1.141, p=0.0355), UTI (OR=1.065, p=0.0016), and opioid prescriptions (OR=1.17, p<0.0001), and significantly lower rates of arrhythmia (OR=0.907, p<0.0001), congestive heart failure (CHF) (OR=0.863, p<0.0001), cardiac arrest (OR=0.637 p<0.0001), pneumonia (OR=0.795, p<0.0001), and transfusion (OR=0.777, p<0.0001). Furthermore, obese patients were significantly more likely to undergo revision within 10 years (OR=1.172, p<0.0001). Under ICD codes, 31,922 obese (45% male) and 31,922 non-obese patients (45% male) were included. Obese patients did not have a significant difference in total cost or drug cost.

Conclusions

Obese patients had significantly higher rates of infection, venous thromboembolic event, wound complication, hematoma, and opioid prescriptions but significantly lower rates of cardiac issues, pneumonia, and transfusion, after hip replacement. Additionally, there was no significant difference in total or drug cost. Therefore, this study did not support our hypothesis that obese patients have worse outcomes than non-obese patients, as there neither was a clear significant increase in complication rates nor a significant increase in costs. However, further research should be done to better understand the complex relationship between obesity and postoperative outcomes.

Overweight patients benefit from high tibial osteotomy to the same extent as patients with normal weights but show inferior mid-term results

PURPOSE

The purpose of this prospective study was to analyze the impact of obesity on the clinical and radiological outcomes 6 years after open-wedge high tibial osteotomy (HTO).

METHODS

A total of 120 prospectively recorded patients with medial compartment osteoarthritis underwent open-wedge HTO between 2008 and 2011. The study cohort was frequently examined over a minimum of a 6-year follow-up. The cohort was divided into three groups according to body mass index (BMI): normal weight patients (BMI < 25 kg/m²), pre-obese patients (BMI 25-30 kg/m²) and obese patients (BMI > 30 kg/m²). Clinical and functional outcomes (Oxford Knee Score, Hospital for Special Surgery Score, Lequesne Score, Tegner Activity Scale), subjective health-related quality of life (SF-36), change in mechanical limb alignment (mTFA) as well as conversion to unicompartmental or total knee arthroplasty (TKA) were evaluated. To compare clinical scoring between the groups, univariate variance analysis was applied. Changes in outcome variables over time were analyzed with dependent t tests.

RESULTS

From 120 patients, 85 were followed-up over a 6.7-year period on average (6-11.8 years) after HTO. The mean BMI was 28.6 ± 4.6 kg/m². Each group showed a significant pre- to postoperative increase in all recorded scores (p < 0.05). In absolute terms, both mental and clinical scores of overweight patients did not reach the peak values of the normal weighted population during the period of observation. There was a conversion to TKA in 10.5% after an average of 50.1 ± 25.0 months following surgery. A total of five complications occurred without significant differences (BMI < 25: n = 1, BMI 25-30: n = 2, BMI > 30: n = 2; n.s.). There was a mean pre- to postoperative (six weeks after surgery) correction difference of 6.9° ± 3.2° (mTFA) with higher loss of correction over time in overweight patients.

CONCLUSION

In terms of clinical outcome and health-related quality of life, overweight patients may receive a benefit from open-wedge HTO to the same extent as patients with normal weights and show similar complication rates. However, they have inferior preoperative clinical and functional results and mid-term results after open-wedge HTO compared to patients with normal weights.

LEVEL OF EVIDENCE

Level III.

Predicting postoperative transfusion in elective total HIP and knee arthroplasty: Comparison of different machine learning models of a case-control study

BACKGROUND

Total joint arthroplasty (TJA) is a very successful orthopedics procedure but associates with a significantly high transfusion rate.

OBJECTIVE

In this study, we aimed to determine predictors of postoperative blood transfusion in patients undergoing elective hip and knee TJA patients and compare the accuracy of machine learning (ML) algorithms in predicting transfusion risk.

METHODS

We utilized data from 12,642 patients undergoing primary unilateral TJA. Risk factors and demographic information were extracted, and predictive models were developed using seven ML algorithms. The area under the receiver operating characteristic curve was used to measure the predictive accuracy of each algorithm.

RESULTS

The overall transfusion rate was 18.7%. Patient-related risk factors for transfusion included age 65-85 (Odds Ratio (OR): 1.175-1.222), female (OR: 1.246), American Society of Anesthesiologists grade Ⅱ or greater (OR: 1.264-2.758). Surgical factors included operation time (OR: 1.736), drain use (OR: 2.202) as well as intraoperative blood loss (OR: 7.895). Elevated preoperative Hb (OR: 0.615), Hct (OR: 0.800), BMI (≥24 kg/m2) (OR: 0.613-0.731) and tranexamic acid use (OR: 0.375) were associated with decreased risk of postoperative transfusion. The long short-term memory networks (LSTM) and random forest (RF) models achieved the highest predictive accuracy (p < 0.001).

CONCLUSION

The risk factors identified in the current study can provide specific, personalized postoperative transfusion risk assessment for a patient considering lower limb TJA. Furthermore, the predictive accuracies of LSTM and RF algorithms were significantly higher than the others, making them potential tools for future personalized preoperative prediction of risk for postoperative transfusion.

Preoperative Education for Total Joint Arthroplasty: Does Reimbursement Reduction Threaten Improved Outcomes?

BACKGROUND

Nurse navigation programs have been previously shown to reduce cost and improve outcomes after total joint arthroplasty (TJA). Medicare has proposed a 13.7% reduction in professional fee reimbursement for TJA procedures that may adversely impact providers' and health systems' ability to fund ancillary support resources such as nurse navigators.

METHODS

A consecutive series of primary TJAs performed between April 2019 and February 2020 was retrospectively reviewed. Clinical and financial outcomes of patients attending a nurse navigator-led preoperative education class were compared with those who did not attend.

RESULTS

There were 2057 TJAs identified during the study period. Most patients attended the preoperative education class (82.7%) and were discharged home (92.8%). Controlling for significant differences between groups, class attendance was associated with reduced length of stay (LOS), increased chance of 0- or 1-day LOS, reduced chance of discharge to a skilled nursing facility, and reduced hospital charges. For this patient sample, a proposed 13.7% reduction in nurse navigator-led classes was modeled to increase overall cost to payers by >$400,000 annually. Complete elimination of this class was estimated to increase the total annual cost by >$5,700,000 and cost per TJA by >$2700.

CONCLUSION

The use of a nurse navigator-led preoperative education class was associated with shorter LOS, more frequent 0- and 1-day LOS, reduced discharge to skilled nursing facilities, and lower total hospital charges for those patients who attended. Potential reductions proposed by Medicare may interfere with the ability to support such services and negatively impact both clinical and financial outcomes.

Patient-Related Risk Factors for Unplanned 30-Day Hospital Readmission Following Primary and Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

Total knee arthroplasty (TKA) is a highly effective procedure for advanced osteoarthritis of the knee. Thirty-day hospital readmission is an adverse outcome related to complications, which can be mitigated by identifying associated risk factors. We aimed to identify patient-related characteristics associated with unplanned 30-day readmission following TKA, and to determine the effect size of the association between these risk factors and unplanned 30-day readmission. We searched MEDLINE and EMBASE from inception to 8 September 2020 for English language articles. Reference lists of included articles were searched for additional literature. Patients of interest were TKA recipients (primary and revision) compared for 30-day readmission to any institution, due to any cause, based on patient risk factors; case series were excluded. Two reviewers independently extracted data and carried out critical appraisal. In-hospital complications during the index admission were the strongest risk factors for 30-day readmission in both primary and revision TKA patients, suggesting discharge planning to include closer post-discharge monitoring to prevent avoidable readmission may be warranted. Further research could determine whether closer monitoring post-discharge would prevent unplanned but avoidable readmissions. Increased comorbidity burden correlated with increased risk, as did specific comorbidities. Body mass index was not strongly correlated with readmission risk. Demographic risk factors included low socioeconomic status, but the impact of age on readmission risk was less clear. These risk factors can also be included in predictive models for 30-day readmission in TKA patients to identify high-risk patients as part of risk reduction programs.