Background

Understanding the type and magnitude of services that patients receive postdischarge and the financial impact of readmissions is crucial to assessing the feasibility of accepting bundled payments.

Questions/purposes

The purposes of this study were to (1) determine the cost and service components of a 30-day total joint arthroplasty (TJA) episode of care; (2) analyze the portion of the total payment that is used for postdischarge services, including home care; and (3) to evaluate the frequency of readmissions and their impact on total episode-of-care payments.

Methods

All payments to Medicare providers (hospitals, postacute care facilities, physicians, and other healthcare providers) for services beginning with the index procedure and extending 30-days postdischarge were analyzed for 250 Medicare beneficiaries undergoing primary or revision TJA from a single institution over a 12 months. Payments and services were aggregated by procedure type and categorized as index procedure, postacute care, and related hospital readmissions.

Results

Mean episode-of-care payments ranged from USD 25,568 for primary TJA in patients with no comorbidities to USD 50,648 for revision TJA in patients with major comorbidities or complications, with wide variability within and across procedures. Postdischarge payments accounted for 36% of total payments. A total of 49% of patients were transferred to postacute care facilities, accounting for 70% of postdischarge payments. The overall 30-day unplanned readmission rate was 10%, accounting for 11% of postdischarge payments.

Conclusions

Episode-of-care payments for TJAs vary widely depending on the type of procedure, patient comorbidities and complications, discharge disposition, and readmission rates. Postdischarge care accounted for more than one-third of total episode payments and varied substantially across patients and procedures.

Background

Total knee arthroplasty (TKA) and related interventions such as revision TKA and the treatment of infected TKAs are commonly performed procedures. Hospital readmission rates are used to measure hospital performance, but risk factors (both medical and surgical) for readmission after TKA, revision TKA, and treatment for the infected TKA have not been well characterized.

Questions/purposes

We measured (1) the unplanned hospital readmission rate in primary TKA and revision TKA, including antibiotic-spacer staged revision TKA to treat infection. We also evaluated (2) the medical and surgical causes of readmission and (3) risk factors associated with unplanned hospital readmission.

Methods

This retrospective cohort study included a total of 1408 patients (1032 primary TKAs, 262 revision TKAs, 113 revision of infected TKAs) from one institution. All hospital readmissions within 90 days of discharge were evaluated for timing and cause. Diagnoses at readmission were categorized as surgical or medical. Readmission risk was assessed using a Cox proportional hazards model that incorporated patient demographics and medical comorbidities.

Results

The unplanned readmission rate for the entire cohort was 4% at 30 days and 8% at 90 days. At 90 days postoperatively, revision of an infected TKA had the highest readmission rate, followed by revision TKA, with primary TKA having the lowest rate. Approximately three-fourths of readmissions were the result of surgical causes, mostly infection, arthrofibrosis, and cellulitis, whereas the remainder of readmissions were the result of medical causes. Procedure type (primary TKA versus revision TKA or staged treatment for infected TKA), hospital stay more than 5 days, discharge destination, and a fluid/electrolyte abnormality were each associated with risk of unplanned readmission.

Conclusions

Patients having revision TKA, whether for infection or other causes, are more likely to have an unplanned readmission to the hospital than are patients having primary TKA. When assessing hospital performance for TKA, it is important to distinguish among these surgical procedures.

Background

Metal-on-metal hip resurfacing arthroplasty (MoM HRA) may offer potential advantages over total hip arthroplasty (THA) for certain patients with advanced osteoarthritis of the hip. However, the cost effectiveness of MoM HRA compared with THA is unclear.

Questions/purposes

The purpose of this study was to compare the clinical effectiveness and cost-effectiveness of MoM HRA to THA.

Methods

A Markov decision model was constructed to compare the quality-adjusted life-years (QALYs) and costs associated with HRA versus THA from the healthcare system perspective over a 30-year time horizon. We performed sensitivity analyses to evaluate the impact of patient characteristics, clinical outcome probabilities, quality of life and costs on the discounted incremental costs, incremental clinical effectiveness, and the incremental cost-effectiveness ratio (ICER) of HRA compared to THA.

Results

MoM HRA was associated with modest improvements in QALYs at a small incremental cost, and had an ICER less than $50,000 per QALY gained for men younger than 65 and for women younger than 55. MoM HRA and THA failure rates, device costs, and the difference in quality of life after conversion from HRA to THA compared to primary THA had the largest impact on costs and quality of life.

Conclusions

MoM HRA could be clinically advantageous and cost-effective in younger men and women. Further research on the comparative effectiveness of MoM HRA versus THA should include assessments of the quality of life and resource use in addition to the clinical outcomes associated with both procedures.

Level of evidence

Level I, economic and decision analysis. See Guidelines for Authors for a complete description of levels of evidence.

Background

Total hip arthroplasty (THA) is a beneficial and cost-effective procedure for patients with osteoarthritis. Recent initiatives to improve hospital quality of care include assessing unplanned hospital readmission rates. Patients presenting for THA have different indications and medical comorbidities that may impact rates of readmission.

Questions/purposes

This study measured (1) the unplanned hospital readmission rate in primary THA, revision THA, and antibiotic-spacer staged revision THA to treat infection. Additionally, we determined (2) the medical and surgical causes of readmission; and (3) the risk factors associated with unplanned readmission.

Methods

A total of 1415 patients (988 primary THA, 344 revision THA, 82 antibiotic-spacer staged revision THA to treat infection) from a single institution were included. All hospital readmissions within 90 days of discharge were reviewed. Patient demographics and medical comorbidities were included in a Cox proportional hazards model to assess risk of readmission.

Results

The overall unplanned readmission rate was 4% at 30 days and 7% at 90 days. At 90 days, primary THA (5%) had a lower unplanned readmission rate than revision THA (10%, p < 0.001) and antibiotic-spacer staged revision THA (18%, p < 0.001). Medical diagnoses were responsible for almost one-fourth of unplanned readmissions, whereas over half of surgical readmissions were the result of dislocation, surgical site infection, and postoperative hematoma. Type of procedure, hospital stay greater than 5 days, cardiac valvular disease, diabetes with end-organ complications, and substance abuse were each associated with increased risk of unplanned readmission.

Conclusions

Higher rates of unplanned hospital readmissions in revision THA rather than primary THA suggest that healthcare quality measures that incorporate readmission rates as a proxy for quality of care should distinguish between primary and revision procedures. Failure to do so may negatively impact tertiary referral hospitals that often care for patients requiring complex revision procedures.

Background

The variation in articular cartilage thickness (ACT) in healthy knees is difficult to quantify and therefore poorly documented. Our aims are to (1) define how machine learning (ML) algorithms can automate the segmentation and measurement of ACT on magnetic resonance imaging (MRI) (2) use ML to provide reference data on ACT in healthy knees, and (3) identify whether demographic variables impact these results.

Methods

Patients recruited into the Osteoarthritis Initiative with a radiographic Kellgren-Lawrence grade of 0 or 1 with 3D double-echo steady-state MRIs were included and their gender, age, and body mass index were collected. Using a validated ML algorithm, 2 orthogonal points on each femoral condyle were identified (distal and posterior) and ACT was measured on each MRI. Site-specific ACT was compared using paired t-tests, and multivariate regression was used to investigate the risk-adjusted effect of each demographic variable on ACT.

Results

A total of 3910 MRI were included. The average femoral ACT was 2.34 mm (standard deviation, 0.71; 95% confidence interval, 0.95-3.73). In multivariate analysis, distal-medial (-0.17 mm) and distal-lateral cartilage (-0.32 mm) were found to be thinner than posterior-lateral cartilage, while posterior-medial cartilage was found to be thicker (0.21 mm). In addition, female sex was found to negatively impact cartilage thickness (OR, -0.36; all values: P < .001).

Conclusion

ML was effectively used to automate the segmentation and measurement of cartilage thickness on a large number of MRIs of healthy knees to provide normative data on the variation in ACT in this population. We further report patient variables that can influence ACT. Further validation will determine whether this technique represents a powerful new tool for tracking the impact of medical intervention on the progression of articular cartilage degeneration.

Background

The role of vancomycin in surgical antimicrobial prophylaxis and high-risk patients who are most likely to benefit remains unclear.

Questions/purposes

We determined the impact of targeted use of vancomycin on (1) the incidence of periprosthetic joint infection (PJI); and (2) the incidence of PJI from methicillin-resistant organisms in patients undergoing revision total knee arthroplasty (TKA) at our institution.

Methods

In an effort to reduce PJI rates, we added vancomycin to cefazolin as surgical antimicrobial prophylaxis for patients undergoing revision TKA in October 2010. Internal data indicated a high rate of PJI in revision TKA and in particular PJI resulting from methicillin-resistant organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). We retrospectively reviewed infection control surveillance data on 414 revision TKAs performed between July 2008 and June 2012 (fiscal years 2009-2012).

Results

The overall rate of PJI in fiscal years 2009-2010 among 190 patients undergoing revision TKA was 7.89%. After the change in surgical antimicrobial prophylaxis, there was a significant reduction in PJI among patients undergoing revision TKA in fiscal years 2011-2012 to 3.13% (p = 0.046). In particular, we observed a reduction in PJI resulting from methicillin-resistant organisms over this same time period, from 4.21% to 0.89% (p = 0.049).

Conclusions

Targeted use of vancomycin in patients undergoing revision TKA was effective in reducing the rate of PJI and PJI resulting from methicillin-resistant organisms in an institution with a high baseline rate of PJI due to MRSA and MRSE. Identification of high-risk subgroups of patients within a surgical population can help target infection prevention strategies to those who are most likely to benefit and thus minimize potential risks (eg, selection of resistant organisms, adverse drug events) associated with broader application of such an intervention.

Background

Little is known about the relative efficacy of open (OGR) vs endoscopic (EGR) gluteal tendon repair of gluteal tendon tears in minimizing pain and restoring function. Our aim is to compare these 2 surgical techniques and quantify their impact on clinical outcomes.

Methods

All patients undergoing gluteal tendon tear repair at our institution between 2015 and 2018 were retrospectively reviewed. Pain scores, limp, hip abduction strength, and the use of analgesics were recorded preoperatively and at last follow-up. The Hip disability and Osteoarthritis Outcome Score Junior and Harris Hip Score Section1 were obtained at last follow-up. Fatty degeneration was quantified using the Goutallier-Fuchs Classification (GFC). Statistical analysis was conducted using one-way analysis of variance and t-tests.

Results

Forty-five patients (mean age 66, 87% females) met inclusion criteria. Average follow-up was 20.3 months. None of the 10 patients (22%) undergoing EGR had prior surgery. Of 35 patients (78%) undergoing OGR, 12 (27%) had prior hip replacement (75% via lateral approach). The OGRs had more patients with GFC ≥2 (50% vs 11%, P = .02) and used more anchors (P = .03). Both groups showed statistical improvement (P ≤ .01) for all outcomes measured. GFC >2 was independently associated with a worst limp and Harris Hip Score Section 1 score (P = .05). EGR had a statistically higher opioid use reduction (P < .05) than OGR. Other comparisons between EGR and OGR did not reach statistical significance.

Conclusion

In this series, open vs endoscopic operative approach did not impact clinical outcomes. More complex tears were treated open and with more anchors. Fatty degeneration adversely impacted outcomes. Although further evaluation of the efficacy of EGR in complex tears is indicated, both approaches can be used successfully.

Introduction

Advances in surgical technique, implant design, and clinical care pathways have resulted in higher expectations for improved clinical outcomes after primary THA; however, despite these advances, it is unclear whether the risk of revision THA actually has decreased with time. Understanding trends in short- and mid-term risks of revision will be helpful in directing clinical, research, and policy efforts to improve THA outcomes.

Question/purposes

We therefore asked (1) whether there have been changes in overall short- and mid-term risks of revision THA among patients in the Medicare population who underwent primary THA between 1998 and 2010; and (2) whether there are different demographic factors associated with short- and mid- term risks of revision THA.

Methods

Using the Medicare 5% national sample database, patients who underwent primary THA between 1998 and 2010 followed by subsequent revision through 2011 were identified by ICD-9-CM procedure codes 81.51 and 81.53/80.05/00.70-00.73, respectively. This dataset included a random sample of Medicare beneficiaries based on their social security number. Only patients with minimum 1-year followup after primary THA were included in our analysis. A total of 64,260 patients who underwent primary THA were identified from the 1998 to 2010 Medicare 5% dataset. Eighty-eight percent of the patients had 1-year followup providing a final study cohort of 56,700 patients. The risk of revision was evaluated at 1, 3, 5, and 7 years. Multivariate Cox regression was used to evaluate temporal trends in revision risk using two methods to account for time effects with periods 1998 to 2002, 2003 to 2007, and 2008 to 2010 for the index year of primary THA, and individual year of index of primary THA as independent variables. The analysis adjusted for patient age, sex, race, census region, Charlson score, and socioeconomic status.

Results

The 7-year crude risk of revision THA declined from 7.10% in 1998 to 2002 to 6.09% in 2008 to 2010, representing a 14.4% overall reduction in adjusted risk of revision (p = 0.0058; 95% CI, 4.4%-23%). Similarly, the 5-year crude risk of revision THA declined from 5.96% in 1998 to 2002 to 5.11% in 2008 to 2010, representing a 14.2% overall reduction in adjusted risk of revision (p = 0.0069; 95% CI, 4.1%-23%). However, the adjusted risk of revision THA at 3 years was not different from 1998 to 2002 (4.70%) and 2008 to 2010 (4.03%; p = 0.1176). Similarly, the adjusted risk of revision at 1 year did not differ from 1998 to 2002 (2.83%) and 2008 to 2010 (2.42%; p = 0.3386). Patients with more comorbidities had a greater adjusted risk of revision (p < 0.001) at all times: 94% (95% CI, 58%-138%) and 56% (95% CI, 33%-84%) at 1 year and 7 years, respectively, for Charlson score of 5+ vs 0).

Conclusions

Although the mid-term (5 and 7 years) risk of revision THA has decreased during the past 14 years among Medicare beneficiaries who underwent primary THA, the short-term risk has not. These findings suggest that greater clinical, research, and policy emphasis is needed to identify potentially avoidable causes of early failure after primary THA in patients in the Medicare population, and multistakeholder solutions are needed to optimize short-term outcomes.

Level of evidence

Level III, therapeutic study.

Objectives

To characterize the morphology and imaging findings of femoral head subchondral insufficiency fractures (SIF), and to investigate clinical outcomes in relation to imaging findings.

Methods

Fifty-one patients with hip/pelvis magnetic resonance (MR) images and typical SIF characteristics were identified and reviewed by two radiologists. Thirty-five patients had follow-up documentation allowing assessment of clinical outcome. Subgroup comparisons were performed using regression models adjusted for age and body mass index.

Results

SIF were frequently associated with cartilage loss (35/47, 74.5 %), effusion (33/42, 78.6 %), synovitis (29/44, 66 %), and bone marrow oedema pattern (BMEP) (average cross-sectional area 885.7 ± 730.2 mm(2)). Total hip arthroplasty (THA) was required in 16/35 patients, at an average of 6 months post-MRI. Compared to the THA cohort, the non-THA group had significantly (p < 0.05) smaller overlying cartilage defect size (10 mm vs. 29 mm), smaller band length ratio and fracture diameters, and greater incidence of parallel fracture morphology (p < 0.05). Male gender and increased age were significantly associated with progression, p < 0.05.

Conclusions

SIF were associated with synovitis, cartilage loss, effusion, and BMEP. Male gender and increased age had a significant association with progression to THA, as did band length ratio, fracture diameter, cartilage defect size, and fracture deformity/morphology.

Key points

• Femoral head subchondral insufficiency fractures (SIF) frequently require total hip arthroplasty (THA). • SIF frequently coexist with synovitis, cartilage loss, and bone marrow oedema pattern. • SIF cartilage defect size, band length ratio, and fracture diameter/morphology can predict progression risk.

Metal-on-metal hip resurfacing arthroplasty (MoM HRA) may offer potential advantages over total hip arthroplasty (THA) for certain patients with advanced osteoarthritis of the hip. However, the cost effectiveness of MoM HRA compared with THA is unclear. The purpose of this study was to compare the clinical effectiveness and cost-effectiveness of MoM HRA to THA. A Markov decision model was constructed to compare the quality-adjusted life-years (QALYs) and costs associated with HRA versus THA from the healthcare system perspective over a 30-year time horizon. We performed sensitivity analyses to evaluate the impact of patient characteristics, clinical outcome probabilities, quality of life and costs on the discounted incremental costs, incremental clinical effectiveness, and the incremental cost-effectiveness ratio (ICER) of HRA compared to THA. MoM HRA was associated with modest improvements in QALYs at a small incremental cost, and had an ICER less than $50,000 per QALY gained for men younger than 65 and for women younger than 55. MoM HRA and THA failure rates, device costs, and the difference in quality of life after conversion from HRA to THA compared to primary THA had the largest impact on costs and quality of life. MoM HRA could be clinically advantageous and cost-effective in younger men and women. Further research on the comparative effectiveness of MoM HRA versus THA should include assessments of the quality of life and resource use in addition to the clinical outcomes associated with both procedures. Level I, economic and decision analysis. See Guidelines for Authors for a complete description of levels of evidence.