Overweight and Obese Patients Require Total Hip and Total Knee Arthroplasty at a Younger Age

Racialized Inequities in Knee Arthroplasty Receipt After Osteoarthritis Diagnosis in the US Military Health System

OBJECTIVE

The goal was to evaluate institutional inequities in the US Military Health System in knee arthroplasty receipt within three years of knee osteoarthritis diagnosis when accounting for other treatments received (eg, physical therapy, medications).

METHODS

In this retrospective observational cohort study, medical record data of patients (n = 29,734) who received a primary osteoarthritis diagnosis in the US Military Health System between January 2016 and January 2020 were analyzed. Data included receipt of physical therapy one year before diagnosis and up to three years after diagnosis, prediagnosis opioid and nonopioid prescription receipt, health-related factors associated with levels of racism, and the primary outcome, knee arthroplasty receipt within three years after diagnosis.

RESULTS

In a generalized additive model with time-varying covariates, Asian and Pacific Islander (incidence rate ratio [IRR] 0.58, 95% confidence interval [CI] 0.45-0.74), Black (IRR 0.52, 95%CI 0.46-0.59), and Latine (IRR 0.66, 95%CI 0.52-0.85) patients experienced racialized inequities in knee arthroplasty receipt, relative to white patients (all P < 0.001).

CONCLUSIONS

In the present sample, Asian and Pacific Islander, Black, and Latine patients were significantly less likely to receive a knee arthroplasty, relative to white patients. Taken together, system-level resources are needed to identify and address mechanisms underlying institutional inequities in knee arthroplasty receipt, such as factors related to systemic and structural, institutional, and personally mediated racism.

Short stem hip arthroplasty with the optimys prosthesis is a safe and effective option for obese patients: a mid-term follow-up multicenter study

INTRODUCTION

Short stems are a valuable option in young patients undergoing total hip arthroplasty (THA) because of their bone stock preserving properties facilitating revision hip arthroplasty. Although the effect of obesity on conventional THA is well studied, data about short stem THA in obese patients are lacking. Therefore, this study aimed to investigate the influence of obesity on complications, revisions, and outcome after short stem THA.

MATERIALS AND METHODS

This multicenter, observational cohort study included patients undergoing short stem THA with the optimys prosthesis. Follow-up examinations were performed at specific intervals up to 7 years postoperatively. Operation characteristics, general and specific complications, revisions, VAS rest pain, VAS load pain, VAS patient satisfaction, and Harris Hip Score (HHS) were recorded and statistically compared between obese (BMI ≥ 30 kg/m2) and non-obese (BMI < 30 kg/m2) patients.

RESULTS

Of the 224 patients included with a mean follow-up of 87.2 months (range 81.9-104.0), 69 were assigned to the OB group and 155 to the non-OB group. A minimally invasive approach was significantly less often selected in obese patients (p = 0.049), whereas operating time and length of hospital stay were not significantly different. The rate of general and specific complications did not significantly differ between both groups. Survival of the optimys prosthesis was 99.1% at 7-year follow-up and one patient per group had to undergo revision surgery. VAS rest pain, load pain, and satisfaction improved from preoperatively to postoperatively in both groups without a significant difference between both groups. While the HHS was improved from preoperatively to postoperatively, obese patients showed a significantly lower HHS at the 7-year follow-up (p = 0.01) but still exhibited an excellent scoring above the PASS threshold.

CONCLUSION

Short stem THA with the optimys prosthesis is a safe and effective option also in obese patients with an excellent clinical outcome and a low complication rate.

Potential diagnostic markers and biological mechanism for osteoarthritis with obesity based on bioinformatics analysis

Numerous observational studies have shown that obesity (OB) is a significant risk factor in the occurrence and progression of osteoarthritis (OA), but the underlying molecular mechanism between them remains unclear. The study aimed to identify the key genes and pathogeneses for OA with OB. We obtained two OA and two OB datasets from the gene expression omnibus (GEO) database. First, the identification of differentially expressed genes (DEGs), weighted gene co-expression network analysis (WGCNA), and machine learning algorithms were used to identify key genes for diagnosing OA with OB, and then the nomogram and receiver operating characteristic (ROC) curve were conducted to assess the diagnostic value of key genes. Second, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to explore the pathogenesis of OA with OB. Third, CIBERSORT was created to investigate immunocyte dysregulation in OA and OB. In this study, two genes (SOD2, ZNF24) were finally identified as key genes for OA with OB. These two key genes had high diagnostic values via nomogram and ROC curve calculation. Additionally, functional analysis emphasized that oxidative stress and inflammation response were shared pathogenesis of OB and AD. Finally, in OA and OB, immune infiltration analysis showed that SOD2 closely correlated to M2 macrophages, regulatory T cells, and CD8 T cells, and ZNF24 correlated to regulatory T cells. Overall, our findings might be new biomarkers or potential therapeutic targets for OA and OB comorbidity.

Comparing Risk Assessment Between Payers and Providers: Inconsistent Agreement in Medical Comorbidity Records for Patients Undergoing Total Joint Arthroplasty

BACKGROUND

The proper risk adjustment for total hip arthroplasty (THA) and total knee arthroplasty (TKA) relies on an accurate assessment of comorbidity profiles by both the payer and the institution. The purpose of this study was to determine how strongly comorbidities tracked by our institution agreed with the same comorbidities reported by payers in patients undergoing THA and TKA.

METHODS

All patients of a single payer undergoing primary THA and TKA at a single institution between January 5, 2021 and March 31, 2022 were included (n = 876). There were 8 commonly collected medical comorbidities obtained from institutional medical records and matched with patient records reported by the payer. Fleiss Kappa tests were used to determine agreement of payer data with institutional records. There were 4 medical risk calculations collected from our institutional records and compared with an insurance member risk score reported by the payer.

RESULTS

Comorbidities reported by the institution differed significantly from those reported by payers, with Kappa varying between 0.139 and 0.791 for THA, and 0.062 and 0.768 for TKA. Diabetes was the only condition to demonstrate strong agreement for both procedures (THA; k = 0.791, TKA; k = 0.768). The insurance member risk score demonstrates the closest association with total cost and surplus for THA regardless of insurance type and for TKA procedures paid for with private commercial insurance.

CONCLUSION

There is a lack of agreement between medical comorbidities within payer and institutional records for both THA and TKA. These differences may put institutions at a disadvantage within value-based care models and when optimizing patients perioperatively.

Improved 2-Year Freedom from Arthroplasty in Patients with High-Risk SIFK Scores and Medial Knee Osteoarthritis Treated with an Implantable Shock Absorber versus Non-Operative Care

OBJECTIVE

Subchondral insufficiency fracture of the knee (SIFK) is associated with high rates of osteoarthritis (OA) and arthroplasty. The implantable shock absorber (ISA) is an extra-capsular implant that unloads the medial knee compartment. This study compared the 2-year freedom from arthroplasty rates in subjects with medial knee OA and SIFK when treated with an ISA versus a matched cohort of patients treated non-surgically.

DESIGN

This retrospective case-control study compared 2-year conversion rates to arthroplasty in SIFK score-, age-, and body mass index (BMI)-matched control subjects without prior surgical history with ISA-implanted subjects from an ongoing prospective study. Baseline and final radiographs, and MRIs were reviewed for evaluation of meniscus or ligament injuries, insufficiency fractures, and subchondral edema. Kaplan-Meier analysis assessed survival.

RESULTS

Forty-two patients (21 Control: 21 ISA), mean age = 52.3 ± 8.7 years, BMI = 29.5 ± 3.9 kg/m2, 40% female were evaluated. Both ISA and Control arms had the same numbers of low (n = 4), medium (n = 11), and high-risk (n = 6) SIFK scores. One- and 2-year freedom-from-arthroplasty rates were both 100% for ISA subjects, and 76% and 55%, respectively, for Controls (P = 0.001 for cross-group comparison). Control knees with low, medium, and high-risk SIFK scores had respective 1- and 2-year survival rates of 100% and 100%, 90% and 68% (P = 0.07 vs. ISA), and 33% and 0% (P = 0.002 vs. ISA).

CONCLUSIONS

ISA intervention was strongly associated with avoidance of arthroplasty at a minimum 2 years, especially in patients with high-risk SIFK scores. SIFK severity scoring predicted relative risk of conversion to arthroplasty through at least 2 years in non-surgically treated subjects.

Is the Direct Anterior Approach for Total Hip Arthroplasty Effective in Obese Patients? Early Clinical and Radiographic Results from a Retrospective Comparative Study

Background and objectives: Total hip arthroplasty (THA) in obese patients (BMI > 30) is considered technically demanding, and it is associated with higher rates of general and specific complications including infections, component malpositioning, dislocation, and periprosthetic fractures. Classically, the Direct Anterior Approach (DAA) has been considered less suitable for performing THA surgery in the obese patient, but recent evidence produced by high-volume DAA THA surgeons suggests that DAA is suitable and effective in obese patients. At the authors' institution, DAA is currently the preferred approach for primary and revision THA surgery, accounting for over 90% of hip surgeries without specific patient selection. Therefore, the aim of the current study is to evaluate any difference in early clinical outcomes, perioperative complications, and implant positioning after primary THAs performed via DAA in patients who were divided according to BMI. Material and methods: This study is a retrospective review of 293 THA implants in 277 patients that were performed via DAA from 1 January 2016 to 20 May 2020. Patients were further divided according to BMI: 96 patients were normal weight (NW), 115 were overweight (OW), and 82 were obese (OB). All the procedures were performed by three expert surgeons. The mean follow-up was 6 months. Patients' data, American Society of Anesthesiologists (ASA) score, surgical time, days in rehab unit, pain at the second post-operative day recorded by using a Numerical Rating Scale (NRS), and number of blood transfusions were recorded from clinical charts and compared. Radiological evaluation of cup inclination and stem alignment was conducted on post-operative radiographs; intra- and post-operative complications at latest follow-up were recorded. Results: The average age at surgery of OB patients was significantly lower compared to NW and OW patients. The ASA score was significantly higher in OB patients compared to NW patients. Surgical time was slightly but significantly higher in OB patients (85 ± 21 min) compared to NW (79 ± 20 min, p = 0.05) and OW patients (79 ± 20 min, p = 0.029). Rehab unit discharge occurred significantly later for OB patients, averaging 8 ± 2 days compared to NW patients (7 ± 2 days, p = 0.012) and OW patients (7 ± 2 days; p = 0.032). No differences in the rate of early infections, number of blood transfusions, NRS pain at the second post-operative day, and day of post-operative stair climbing were found among the three groups. Acetabular cup inclination and stem alignment were similar among the three groups. The perioperative complication rate was 2.3%; that is, perioperative complication occurred in 7 out of 293 patients, with a significantly higher incidence of surgical revisions required in obese patients compared to the others. In fact, OB patients showed a higher revision rate (4.87%) compared to other groups, with 1.04% for NW and 0% for OW (p = 0.028, Chi-square test). Causes for revision in obese patients were aseptic loosening (2), dislocation (1), and clinically significant post-operative leg length discrepancy (1), with a revision rate of 4/82 (4.87%) during follow-up. Conclusions: THA performed via DAA in obese patients could be a solid choice of treatment, given the relatively low rate of complications and the satisfying clinical outcomes. However, surgical expertise on DAA and adequate instrumentation for this approach are required to optimise the outcomes.

Does body mass index influence long-term outcomes after anatomic total shoulder arthroplasty?

BACKGROUND

As of 2018, upwards of 42% of the US adult population was considered obese based on body mass index (BMI) scales. With the annual number of total joint replacements increasing, this study aimed to evaluate the impact BMI has on anatomic total shoulder arthroplasty (aTSA) outcomes.

METHODS

This was a retrospective analysis of 128 shoulders requiring primary aTSA. Patients were stratified into 3 cohorts based on their BMI at surgery: underweight/normal weight (U/NW; BMI ≤25.0), overweight (25.0 < BMI ≤ 30.0), and obese (BMI >30.0). BMI was separately analyzed as a continuous variable. Clinical endpoints were range of motion scores, including forward elevation, external rotation, and internal rotation, and patient-reported outcomes, including visual analog scale (VAS) scores, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores, and the Simple Shoulder Test (SST). Survivorship curves were calculated using Kaplan-Meier analysis.

RESULTS

Forty-four, 50, and 34 patient shoulders were in the U/NW, overweight, and obese cohorts, respectively. The mean follow-up time was 11.4 years. The U/NW cohort had more females (73%) compared with the overweight (34%; P = .0030) and obese (35%; P = .0015) groups; no differences were seen in revision rates. BMI was negatively correlated with age at surgery (r = -0.19, P = .014); it was not correlated with any of the 6 postoperative clinical endpoints. All 3 cohorts saw significant improvements in forward elevation, external rotation, internal rotation and VAS, ASES, and SST scores when compared preoperatively to postoperatively (P < .001). There were no significant differences between the 3 cohorts with respect to postoperative range of motion. Postoperative ASES scores were higher for the overweight cohort (82.6 ± 18.6) compared with both the U/NW (63.0 ± 25.1) and obese cohorts (70.5 ± 26.8) (P < .001). The overweight cohort also had higher SST (P = .0012) postoperative scores compared with the U/NW and obese cohorts; VAS scores were comparable between groups (P = .12). The nonobese (BMI <30) group (n = 94) showed 5-, 10-, and 15-year implant survival of 98.9%, 94.9%, and 83.9%, respectively compared to 97.1%, 93.7%, and 87.0% in the obese (BMI ≥30) group (n = 34). The log rank test revealed no significant difference in survival curves (P = .82).

CONCLUSION

To our knowledge, this is the longest follow-up study analyzing clinical endpoints stratified by BMI for aTSA. We saw that patients with a higher BMI required shoulder replacement at a significantly younger age. However, we also report that regardless of BMI, all patients saw significant improvements in patient-reported outcomes and range of motion scores postoperatively.

Mid-Term Survival of Total Hip Arthroplasty in Patients Younger Than 55-year-old

BACKGROUND

Survivorship of total hip arthroplasty (THA) in younger patients is concerning given the inverse relationship between age and lifetime risk for revision. The purpose of this study is to determine if risk of revision has improved for patients aged 55 years or younger who undergo primary THA using modern polyethylene liners.

METHODS

A retrospective review identified 2,461 consented patients (2,814 hips) with minimum 2-year follow-up who underwent primary THA at our institution between September 2007 and August 2014 using components from a single manufacturer (Zimmer Biomet), all with vitamin E-infused highly crosslinked polyethylene acetabular inserts. There were 561 patients (643 THA; 23%) aged 55 or younger and 1,900 (2,171 THA; 77%) older than 55.

RESULTS

Mean follow-up was 5.0 years for both groups. There were more male patients in the younger (55%) than older (41%) group. Body mass index (BMI) was higher in younger patients independent of gender. Improvement in Harris hip score (HHS) was similar between groups. Kaplan-Meier survival to endpoint of all cause revision was similar between groups at 12 years (P = .8808) with 97.5% (95% CI: ±0.7%) for younger versus 97.1% (95% CI: ±0.6%) for older patients. Most frequent reason for revision overall was periprosthetic femoral fracture (21; 0.75%); univariate analysis revealed risk factors were female gender (P = .28) and age ≥65 years (P = .012).

CONCLUSION

Use of modern polyethylene, such as vitamin E-stabilized highly cross-linked, liners during THA may improve survivorship in younger patients undergoing THA. Younger patients undergoing primary THA with highly cross-linked polyethylene liners had no increased rate of revision at mid-term follow-up.

Obesity is associated with an increased risk of undergoing knee replacement in Australia

Background

Obesity is associated with the development of knee osteoarthritis (OA). The aim of this study was to examine the incidence of obesity in patients undergoing knee replacement (KR) for OA in Australia compared to the incidence of obesity in the general population.

Methods

A cohort study was conducted, comparing data from the Australian Bureau of Statistics (ABS) 2017–2018 National Health Survey with data from the National Joint Replacement Registry. The distribution of patients who underwent KR from July 2017 to June 2018 by BMI category was compared to the distribution of the general population, in age and gender sub‐groups.

Results

During the study period, 35.6% of Australian adults were overweight and 31.3% were obese. Of the 56 217 patients who underwent primary KR for OA, 31.9% were overweight and 57.7% were obese. The relative risk of undergoing KR for OA increased with increasing BMI category. Class 1, 2 and 3 obese females aged 55–64 years were 4.7, 8.4 and 17.3 times more likely to undergo KR than their normal weight counterparts, respectively. Males in the same age and BMI categories were 3.4, 4.5 and 5.8 times more likely to undergo KR, respectively. Class 3 obese patients underwent KR 7 years younger, on average, than normal weight individuals.

Conclusion

Obesity is associated with an increased risk of undergoing KR, and at a younger age, particularly for females. There is an urgent need for a societal level approach to address the prevalence of obesity, to reduce the burden of obesity related KR.

Total knee arthroplasty in patients with severe obesity provides value for money despite increased complications

AIMS

Access to total knee arthroplasty (TKA) is sometimes restricted for patients with severe obesity (BMI ≥ 40 kg/m²). This study compares the cost per quality-adjusted life year (QALY) associated with TKA in patients with a BMI above and below 40 kg/m² to examine whether this is supported.

METHODS

This single-centre study compared 169 consecutive patients with severe obesity (BMI ≥ 40 kg/m²) (mean age 65.2 years (40 to 87); mean BMI 44.2 kg/m² (40 to 66); 129/169 female) undergoing unilateral TKA to a propensity score matched (age, sex, preoperative Oxford Knee Score (OKS)) cohort with a BMI < 40 kg/m² in a 1:1 ratio. Demographic data, comorbidities, and complications to one year were recorded. Preoperative and one-year patient-reported outcome measures (PROMs) were completed: EuroQol five-dimension three-level questionnaire (EQ-5D-3L), OKS, pain, and satisfaction. Using national life expectancy data with obesity correction and the 2020 NHS National Tariff, QALYs (discounted at 3.5%), and direct medical costs accrued over a patient's lifetime, were calculated. Probabilistic sensitivity analysis (PSA) was used to model variation in cost/QALY for each cohort across 1,000 simulations.

RESULTS

All PROMs improved significantly (p < 0.05) in both groups without differences between groups. Early complications were higher in BMI ≥ 40 kg/m²: 34/169 versus 52/169 (p = 0.050). A total of 16 (9.5%) patients with a BMI ≥ 40 kg/m² were readmitted within one year with six reoperations (3.6%) including three (1.2%) revisions for infection. Assuming reduced life expectancy in severe obesity and revision costs, TKA in patients with a BMI ≥ 40 kg/m² costs a mean of £1,013/QALY (95% confidence interval £678 to 1,409) more over a lifetime than TKA in patients with BMI < 40 kg/m². In PSA replicates, the maximum cost/QALY was £3,921 in patients with a BMI < 40 kg/m² and £5,275 in patients with a BMI ≥ 40 kg/m².

CONCLUSION

Higher complication rates following TKA in severely obese patients result in a lifetime cost/QALY that is £1,013 greater than that for patients with BMI < 40 kg/m², suggesting that TKA remains a cost-effective use of healthcare resources in severely obese patients where the surgeon considers it appropriate. Cite this article: Bone Joint J 2022;104-B(4):452-463.

Reporting of Comorbidities in Total Hip and Knee Arthroplasty Clinical Literature: A Systematic Review

BACKGROUND

The effects of comorbid disease remain an area of interest. Concurrent diagnoses not only affect clinical outcomes but also affect health-care reimbursement. As the rate of arthroplasty increases, consistent risk stratification is imperative. Therefore, our aim was to ascertain how comorbidities have been reported in the recent total hip arthroplasty (THA) and total knee arthroplasty (TKA)-related literature; we also wanted to quantify the use of comorbidity scores for the assessment of comorbid disease in arthroplasty research.

METHODS

A systematic review of the recent THA and TKA literature that was published between January 1, 2019, and September 21, 2020, was performed using the PubMed and MEDLINE databases. Clinical studies that provided data on comorbidities were evaluated for method of comorbidity reporting. The prevalence of comorbidity reporting was assessed, and the manner of reporting was analyzed.

RESULTS

Among 659 articles, a total of 207 studies (31.4%) reported comorbidities and met our inclusion criteria. Of the 207 studies that reported comorbidities, only 57% used a comorbidity index to report comorbid disease. Of all of the indices, the American Society of Anesthesiologists (ASA) Physical Status Classification System was the score that was most commonly used (TKA, 86.2%; THA, 83.3%). Additional scores were used at varying frequencies. For TKA, the scores included the Charlson Comorbidity Index (CCI) (15.5%); the New York Heart Association (NYHA) Functional Classification (3.4%); and the CCI-Deyo (adapted by Deyo et al.), the age-adjusted CCI, the Cumulative Illness Rating Scale (CIRS), and the Readmission Risk Assessment Tool (RRAT) (1.7% each). For THA, the scores included the CCI (16.7%), the Elixhauser Comorbidity Measure (ECM) (6.7%), and the CCI-Deyo (1.7%).

CONCLUSIONS

Considering the impact of comorbid disease on outcomes, complications, and, ultimately, reimbursement, standardized risk stratification in arthroplasty is necessary. Current studies demonstrate inconsistent comorbidity reporting, making it challenging to further characterize the impact of comorbidities on outcomes. Future research should target the development of a standardized data-driven model for comorbidity assessment in the orthopaedic patient population.

Sex does not clinically influence the functional outcome of total knee arthroplasty but females have a lower rate of satisfaction with pain relief

Background

The aims were to assess whether sex had a clinically significant independent influence on the outcome of total knee arthroplasty (TKA) according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Short Form (SF-) 12 scores and patient satisfaction at 1 year.

Methods

A retrospective cohort of 3510 primary TKA were identified. Patient demographics, comorbidities, WOMAC and SF-12 scores were collected preoperatively and 1 year postoperatively. Patient satisfaction were assessed at 1 year.

Results

There were 1584 males and 1926 females. The preoperative WOMAC and SF-12 scores were significantly (p < 0.001) worse in females but were not greater than the minimal clinically important difference (MCID). When adjustments had been made for confounding differences, females showed a significantly greater improvement in their function (1.5 points, p = 0.03) and total (1.5 points, p = 0.03) WOMAC scores compared to males, but these were not greater than the MCID. When adjustments had been made for confounding differences, females were less likely to be satisfied with their pain relief (p = 0.03) relative to males.

Conclusion

Sex does not clinically influence the knee specific outcome (WOMAC) or overall generic (SF-12) health 1 year after TKA. However, satisfaction with pain relief after TKA was significantly less likely in female patients.

Level of evidence II

Prognostic retrospective cohort study.