Abstract Periprosthetic joint infection (PJI) represents substantial clinical and economic burdens. This study evaluated patient and procedure characteristics and resource utilization associated with ...revision arthroplasty for PJI. The Nationwide Inpatient Sample (Q4 2005–2010) was analyzed for 235,857 revision THA (RTHA) and 301,718 revision TKA (RTKA) procedures. PJI was the most common indication for RTKA, and the third most common reason for RTHA. PJI was most commonly associated with major severity of illness (SOI) in RTHA, and with moderate SOI in RTKA. RTHA and RTKA for PJI had the longest length of stay. Costs were higher for RTHA/RTKA for PJI than for any other diagnosis except periprosthetic fracture. Epidemiologic differences exist in the rank, severity and populations for RTHA and RTKA for PJI.
Understanding the cause of failure and type of revision total knee arthroplasty (TKA) procedures performed in the United States is essential in guiding research, implant design, and clinical decision ...making in TKA. We assessed the causes of failure and specific types of revision TKA procedures performed in the United States using newly implemented ICD-9-CM diagnosis and procedure codes related to revision TKA data from the Nationwide Inpatient Sample (NIS) database. Clinical, demographic, and economic data were reviewed and analyzed from 60,355 revision TKA procedures performed in the United States between October 1, 2005 and December 31, 2006. The most common causes of revision TKA were infection (25.2%) and implant loosening (16.1%), and the most common type of revision TKA procedure reported was all component revision (35.2%). Revision TKA procedures were most commonly performed in large, urban, nonteaching hospitals in Medicare patients ages 65 to 74. The average length of hospital stay (LOS) for all revision TKA procedures was 5.1 days, and the average total charges were $49,360. However, average LOS, average charges, and procedure frequencies varied considerably by census region, hospital type, and procedure performed.
Level of Evidence:
Level II, economic and decision analysis. See Guidelines for Authors for a complete description of levels of evidence.
Background
Few studies have examined factors that affect acetabular cup positioning. Since cup positioning has been linked to dislocation and increased bearing surface wear, these factors affecting ...cup position are important considerations.
Question/purposes
We determined the percent of optimally positioned acetabular cups and whether patient and surgical factors affected acetabular component position.
Methods
We obtained postoperative AP pelvis and cross-table lateral radiographs on 2061 consecutive patients who received a THA or hip resurfacing from 2004 to 2008. One thousand nine hundred and fifty-two hips had AP pelvic radiographs with correct position of the hip center, and 1823 had both version and abduction angles measured. The AP radiograph was measured using Hip Analysis Suite™ to calculate the cup inclination and version angles, using the lateral film to determine version direction. Acceptable ranges were defined for abduction (30°–45°) and version (5°–25°).
Results
From the 1823 hips, 1144 (63%) acetabular cups were within the abduction range, 1441 (79%) were within the version range, and 917 (50%) were within the range for both. Surgical approach, surgeon volume, and obesity (body mass index > 30) independently predicted malpositioned cups. Comparison of low versus high volume surgeons, minimally invasive surgical versus posterolateral approach, and obesity versus all other body mass index groups showed a twofold (1.5–2.8), sixfold (3.5–10.7), and 1.3-fold (1.1–1.7) increased risk for malpositioned cups, respectively.
Conclusions
Factors correlated to malpositioned cups included surgical approach, surgeon volume, and body mass index with increased risk of malpositioning for minimally invasive surgical approach, low volume surgeons, and obese patients. Further analyses on patient and surgical factors’ influence on cup position at a lower volume medical center would provide a valuable comparison.
Level of Evidence
Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
Abstract Whether there are differences in knee anthropometry between Asian and white knees remains unclear. Three-dimensional knee models were constructed using computed tomography or magnetic ...resonance imaging of healthy Chinese and white subjects. The morphologic measurements of the femur included mediolateral, anteroposterior dimensions, and aspect ratio. The tibial measurements included mediolateral, medial/lateral anteroposterior dimension, aspect ratio, and posterior slope of medial/lateral plateau. The results showed that Chinese knees were generally smaller than white knees. In addition, the femoral aspect ratio of Chinese females was significantly smaller than that of white females (1.24 ± 0.04 vs 1.28 ± 0.06). Tibial aspect ratio differences between Chinese and white males (1.82 ± 0.07 vs 1.75 ± 0.11), though significant, were likely a reflection of differences in knee size between races. These racial differences should be considered in the design of total knee arthroplasty prosthesis for Asian population.
Background
Revision THA and TKA are growing and important clinical and economic challenges. Healthcare systems tend to combine revision joint replacement procedures into a single service line, and ...differences between revision THA and revision TKA remain incompletely characterized. These differences carry implications for guiding care and resource allocation. We therefore evaluated epidemiologic trends associated with revision THAs and TKAs.
Questions/purposes
We sought to determine differences in (1) the number of patients undergoing revision TKA and THA and respective demographic trends; (2) differences in the indications for and types of revision TKA and THA; (3) differences in patient severity of illness scoring between THA and TKA; and (4) differences in resource utilization (including cost and length of stay LOS) between revision THA and TKA.
Methods
The Nationwide Inpatient Sample (NIS) was used to evaluate 235,857 revision THAs and 301,718 revision TKAs between October 1, 2005 and December 31, 2010. Patient characteristics, procedure information, and resource utilization were compared across revision THAs and TKAs. A revision burden (ratio of number of revisions to total number of revision and primary surgeries) was calculated for hip and knee procedures. Severity of illness scoring and cost calculations were derived from the NIS. As our study was principally descriptive, statistical analyses generally were not performed; however, owing to the large sample size available to us through this NIS analysis, even small observed differences presented are likely to be highly statistically significant.
Results
Revision TKAs increased by 39% (revision burden, 9.1%–9.6%) and THAs increased by 23% (revision burden, 15.4%–14.6%). Revision THAs were performed more often in older patients compared with revision TKAs. Periprosthetic joint infection (25%) and mechanical loosening (19%) were the most common reasons for revision TKA compared with dislocation (22%) and mechanical loosening (20%) for revision THA. Full (all-component) revision was more common in revision THAs (43%) than in TKAs (37%). Patients who underwent revision THA generally were sicker (> 50% major severity of illness score) than patients who underwent revision TKA (65% moderate severity of illness score). Mean LOS was longer for revision THAs than for TKAs. Mean hospitalization costs were slightly higher for revision THA (USD 24,697 +/− USD 40,489 SD) than revision TKA (USD 23,130 +/− USD 36,643 SD). Periprosthetic joint infection and periprosthetic fracture were associated with the greatest LOS and costs for revision THAs and TKAs.
Conclusions
These data could prove important for healthcare systems to appropriately allocate resources to hip and knee procedures: the revision burden for THA is 52% greater than for TKA, but revision TKAs are increasing at a faster rate. Likewise, the treating clinician should understand that while both revision THAs and TKAs bear significant clinical and economic costs, patients undergoing revision THA tend to be older, sicker, and have greater costs of care.
Abstract Background Unicompartmental knee arthroplasty (UKA) is a treatment option for single-compartment knee osteoarthritis. Robotic assistance may improve survival rates of UKA, but the ...cost-effectiveness of robot-assisted UKA is unknown. The purpose of this study was to delineate the revision rate, hospital volume, and robotic system costs for which this technology would be cost-effective. Methods We created a Markov decision analysis to evaluate the costs, outcomes, and incremental cost-effectiveness of robot-assisted UKA in 64-year-old patients with end-stage unicompartmental knee osteoarthritis. Results Robot-assisted UKA was more costly than traditional UKA, but offered a slightly better outcome with 0.06 additional quality-adjusted life-years at an incremental cost of $47,180 per quality-adjusted life-years, given a case volume of 100 cases annually. The system was cost-effective when case volume exceeded 94 cases per year, 2-year failure rates were below 1.2%, and total system costs were <$1.426 million. Conclusion Robot-assisted UKA is cost-effective compared with traditional UKA when annual case volume exceeds 94 cases per year. It is not cost-effective at low-volume or medium-volume arthroplasty centers.
Background
Administrative claims data are increasingly being used in public reporting of provider performance and health services research. However, the concordance between administrative claims data ...and the clinical record in lower extremity total joint arthroplasty (TJA) is unknown.
Questions/purposes
We evaluated the concordance between administrative claims and the clinical record for 13 commonly reported comorbidities and complications in patients undergoing TJA.
Methods
We compared 13 administratively coded comorbidities and complications derived from hospital billing records with clinical documentation from a consecutive series of 1350 primary and revision TJAs performed at three high-volume institutions during 2009.
Results
Concordance between administrative claims and the clinical record varied across comorbidities and complications. Concordance between diabetes and postoperative myocardial infarction was reflected by a kappa value > 0.80; chronic lung disease, coronary artery disease, and postoperative venous thromboembolic events by kappa values between 0.60 and 0.79; and for congestive heart failure, obesity, prior myocardial infarction, peripheral arterial disease, bleeding complications, history of venous thromboembolism, prosthetic-related complications, and postoperative renal failure by kappa values between 0.40 and 0.59. All comorbidities and complications had a high degree of specificity (> 92%) but lower sensitivity (29%–100%).
Conclusions
The data suggest administratively coded comorbidities and complications correlate reasonably well with the clinical record. However, the specificity of administrative claims is much higher than the sensitivity, indicating that comorbidities and complications coded in the administrative record were accurate but often incomplete.
Level of Evidence
Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
Hard-on-hard bearings offer the potential to improve the survivorship of total hip arthroplasty implants. However, the specific indications for the use of these advanced technologies remain ...controversial. The purpose of this study was to characterize the epidemiology of bearing surface utilization in total hip arthroplasty in the United States with respect to patient, hospital, geographic, and payer characteristics.
The Nationwide Inpatient Sample database was used to analyze bearing type and demographic characteristics associated with 112,095 primary total hip arthroplasties performed in the United States between October 1, 2005, and December 31, 2006. The prevalence of each type of total hip arthroplasty bearing was calculated for population subgroups as a function of age, sex, census region, payer class, and hospital type.
The most commonly reported bearing was metal-on-polyethylene (51%) followed by metal-on-metal (35%) and ceramic-on-ceramic (14%). Metal-on-polyethylene bearings were most commonly reported in female Medicare patients who were sixty-five to seventy-four years old, while metal-on-metal and ceramic-on-ceramic bearings were most commonly reported in privately insured male patients who were less than sixty-five years old. Thirty-three percent of patients over sixty-five years old had a hard-on-hard bearing reported. There was substantial regional variation in bearing usage; the highest prevalence of metal-on-polyethylene bearings was reported in the Northeast and at nonteaching hospitals, and the highest prevalence of metal-on-metal bearings was reported in the South and at teaching hospitals.
The usage of total hip arthroplasty bearings varies considerably by patient characteristics, hospital type, and geographic location throughout the United States. Despite uncertain advantages in older patients, hard-on-hard bearings are commonly used in patients over the age of sixty-five years. Further study is necessary to define the appropriate indications for these advanced technologies in total hip arthroplasty.
The patient-related risk factors for periprosthetic joint infection and postoperative mortality in elderly patients undergoing total hip arthroplasty are poorly understood. The purpose of this study ...was to identify the specific patient comorbidities that are associated with an increased risk of periprosthetic joint infection and of ninety-day postoperative mortality in U.S. Medicare patients undergoing total hip arthroplasty.
The Medicare 5% sample claims database was used to calculate the relative risk of periprosthetic joint infection and of ninety-day postoperative mortality as a function of preexisting comorbidities in 40,919 patients who underwent primary total hip arthroplasty between 1998 and 2007. The impact of twenty-nine comorbid conditions on periprosthetic joint infection and on postoperative mortality was examined with use of Cox regression, controlling for age, sex, census region, public assistance, and all other baseline comorbidities. The adjusted hazard ratios for all comorbid conditions were evaluated, and the Wald chi-square statistic was used to rank the degree of association of each condition with periprosthetic joint infection and with postoperative mortality. The Bonferroni-Holm method was used to adjust for the multiple comparisons resulting from the number of comorbid conditions analyzed.
Comorbid conditions associated with an increased adjusted risk of periprosthetic joint infection (in decreasing order of significance, p < 0.05 for all comparisons) were rheumatologic disease (hazard ratio HR = 1.71), obesity (HR = 1.73), coagulopathy (HR = 1.58), and preoperative anemia (HR = 1.36). Comorbid conditions associated with an increased adjusted risk of ninety-day postoperative mortality (in decreasing order of significance, p < 0.05 for all comparisons) were congestive heart failure (HR = 2.11), metastatic cancer (HR = 3.14), psychosis (HR = 1.85), renal disease (HR = 1.98), dementia (HR = 2.04), hemiplegia or paraplegia (HR = 2.62), cerebrovascular disease (HR = 1.40), and chronic pulmonary disease (HR = 1.32).
We identified specific patient comorbidities that were independently associated with an increased risk of periprosthetic joint infection and of ninety-day postoperative mortality in Medicare patients who had undergone total hip arthroplasty. This information is important when counseling elderly patients regarding the risks of periprosthetic joint infection and mortality following total hip arthroplasty, as well as for risk adjustment of publicly reported total hip arthroplasty outcomes.
Background
Patient, surgeon, health system, and device factors are all known to influence outcomes in THA. However, patient-related factors associated with an increased risk of early failure are ...poorly understood, particularly in elderly patients.
Questions/purposes
We identified specific demographic and clinical characteristics associated with increased risk of early revision in Medicare patients with THA.
Methods
The Medicare 5% national sample administrative database was used to calculate the relative risk of revision within 12 months following primary THA as a function of baseline medical comorbidities in 56,030 Medicare patients who underwent primary THA between 1998 and 2010. The impact of 29 comorbid conditions on risk of early revision was examined using Cox regression, controlling for age, sex, race, US Census region, socioeconomic status, and all other baseline comorbidities.
Results
Depression, rheumatologic disease, psychoses, renal disease, chronic urinary tract infection, and congestive heart failure were associated with revision THA within 12 months of the index arthroplasty (p ≤ 0.038 for all comparisons; risk factors listed in order of significance).
Conclusions
This information is important when counseling elderly patients with THA regarding the risk of early failure and for risk stratifying publicly reported outcomes in Medicare patients with THA.
Level of Evidence
Level II, prognostic study. See Instructions for Authors for a complete description of levels of evidence.
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