RESUMO
BACKGROUND: Clinical concern exists regarding fretting corrosion and material loss from taper junctions in orthopedic devices, with previous research focusing on the modular components from total hip arthroplasty. Comparatively little has been published regarding the fretting corrosion and material loss in modular knee devices. The purpose of this study is to evaluate fretting corrosion damage and quantify material loss for conical total knee arthroplasty taper interfaces. METHODS: Stem tapers of 166 retrieved modular knee devices were evaluated for fretting corrosion using a semiquantitative scoring method. High precision profilometry was then used to determine volumetric material loss and maximum wear depth for a subset of 37 components (implanted for 0.25-18.76 years). Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize the observed damage. RESULTS: Mild to severe fretting corrosion was observed on the majority of tapers, with 23% receiving a maximum visually determined damage score of 4. The median rate of volumetric material loss was 0.11 mm3/y (range 0.00-0.76) for femoral components (both cone and bore taper surfaces combined) and 0.01 mm3 (range 0.00-8.10) for tibial components. Greater rates of material loss were associated with mixed metal pairings. There was a strong correlation between visual fretting corrosion score and calculated material loss (ρ = 0.68, P < .001). Scanning electron microscopy revealed varying degrees of scratching, wear, fretting corrosion, and instances of cracking with morphology not consistent with fretting corrosion, wear, or fatigue. CONCLUSION: Although visual evidence of fretting corrosion damage was prevalent and correlated with taper material loss, the measured volumetric material loss was low compared with prior reports from total hip arthroplasty.
Assuntos
Artroplastia do Joelho/instrumentação , Prótese de Quadril , Falha de Prótese , Idoso , Corrosão , Feminino , Humanos , Masculino , Teste de Materiais , Metais , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Fraturas Periprotéticas , Desenho de Prótese , Espectrometria por Raios X , Tíbia/ultraestruturaRESUMO
BACKGROUND: We analyzed whether the total hospital cost in a 90-day bundled payment period for ceramic-on-polyethylene (C-PE) and ceramic-on-ceramic (COC) total hip arthroplasty (THA) bearings was changing over time, and whether the cost differential between ceramic bearings and metal-on-polyethylene (M-PE) bearings was approaching the previously published tipping point for cost-effectiveness of US$325. METHODS: A total of 245,077 elderly Medicare patients (65+) who underwent primary THA between 2010 and 2015 were identified from the United States Medicare 100% national administrative hospital claims database. The total inpatient cost, calculated up to 90 days after index discharge, was computed using cost-to-charge ratios, and hospital payment was analyzed. The differential total inpatient cost of C-PE and COC bearings, compared to metal-on-polyethylene (M-PE), was evaluated using parametric and nonparametric models. RESULTS: After adjustment for patient and clinical factors, and the year of surgery, the mean hospital cost up to 90 days for primary THA with C-PE or COC was within ±1% of the cost for primary THA with M-PE bearings (P < .001). From the nonparametric analysis, the median total hospital cost was US$296-US$353 more for C-PE and COC than M-PE. Cost differentials were found to decrease significantly over time (P < .001). CONCLUSION: Patient and clinical factors had a far greater impact on the total cost of inpatient THA surgery than bearing selection, even when including readmission costs up to 90 days after discharge. Our findings indicate that the cost-effectiveness thresholds for ceramic bearings relative to M-PE are changing over time and increasingly achievable for the Medicare population.
Assuntos
Artroplastia de Quadril/economia , Artroplastia de Quadril/instrumentação , Cerâmica , Análise Custo-Benefício , Prótese de Quadril/economia , Desenho de Prótese/economia , Bases de Dados Factuais , Feminino , Humanos , Masculino , Medicare , Metais , Polietileno/economia , Mecanismo de Reembolso , Reoperação/economia , Estados UnidosRESUMO
BACKGROUND: The purpose of this study is to evaluate the impact of prior bariatric surgery on survivorship, outcome, and complications following primary total hip arthroplasty (THA)/total knee arthroplasty (TKA). METHODS: Using the Medicare 5% part B data from 1999 to 2012, we analyzed patients who underwent primary THA (n = 47,895) and primary TKA (n = 86,609). Patients with prior bariatric surgery before arthroplasty were compared to patients with other common metabolic conditions. Kaplan-Meier risk of revision THA/TKA for those with and without bariatric surgery and each of the metabolic bone conditions was calculated. The risk for infection was also evaluated. Regression analysis was used to determine the relative risk of revision at various time intervals for those with and without each of the metabolic conditions. Analysis was also adjusted for the metabolic conditions, age, gender, socioeconomic status, and Charlson comorbidity index. RESULTS: The prevalence of patients with prior bariatric surgery within 24 months of primary THA/TKA was 0.1%. Benchmarked against other common chronic metabolic conditions, bariatric surgery prior to THA was not associated with an increased risk for revision surgery at all measured intervals but positively correlated with increased risk for developing infections. Conversely, patients undergoing primary TKA following bariatric surgery were at increased risk for revision compared to controls but not at increased risk for infection. CONCLUSION: The impact of bariatric surgery prior to elective THA/TKA remains unclear. These patients remain at increased risk for infections following THA and revisions following TKA.