Background

The impact of specific baseline comorbid conditions on the relative risk of postoperative mortality and periprosthetic joint infection (PJI) in elderly patients undergoing TKA has not been well defined.

Questions/purposes

We calculated the relative risk of postoperative mortality and PJI associated with 29 comorbid conditions in Medicare patients undergoing TKA.

Patients and Methods

The Medicare 5% sample was used to calculate the relative risk of 90-day postoperative mortality and PJI as a function of 29 preexisting comorbid conditions in 83,011 patients who underwent primary TKA between 1998 and 2007.

Results

The independent risk factors for 90-day postoperative mortality (in decreasing order of significance) were congestive heart failure, metastatic cancer, renal disease, peripheral vascular disease, cerebrovascular disease, lymphoma, cardiac arrhythmia, dementia, pulmonary circulation disorders, and chronic liver disease. The independent risk factors for PJI (in decreasing order of significance) were congestive heart failure, chronic pulmonary disease, preoperative anemia, diabetes, depression, renal disease, pulmonary circulation disorders, obesity, rheumatologic disease, psychoses, metastatic tumor, peripheral vascular disease, and valvular disease.

Conclusions

We believe this information important when counseling elderly patients regarding the risks of mortality and PJI after TKA and risk-adjusting publicly reported TKA patient outcomes.

Level of Evidence

Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background

A number of recent reports have described novel failure mechanisms of metal-on-metal bearings in total and resurfacing hip arthroplasty. Hip arthroplasties with metal-on-metal articulations are also subject to the traditional methods of failure seen with different bearing couples. There is currently little information in the literature to help guide timely clinical evaluation and management of these patients.

Questions/purposes

We therefore describe the (1) clinical presentations; (2) reasons for failure; (3) operative findings; and (4) histologic findings in patients with failed metal-on-metal hip arthroplasties.

Methods

We retrospectively identified all 37 patients (37 hips) with metal on metal total hip or resurfacing arthroplasties who underwent revision over the past 3 years at our institution. Relevant clinical, radiographic, laboratory, intraoperative, and histopathologic findings were analyzed for all patients.

Results

Of the 37 patients, 10 were revised for presumed hypersensitivity specific to the metal-on-metal articulation. This group included eight patients with tissue histology confirming chronic inflammation with lymphocytic infiltration, eight with aseptic loosening of a monoblock screwless uncemented acetabular component, two with iliopsoas impingement associated with a large-diameter femoral head, and three with femoral neck fracture after resurfacing arthroplasty; the remainder of the patients were revised for infection, instability, component malposition, and periprosthetic fracture.

Conclusions

Increased awareness of the modes of failure will bring to light the potential complications particular to metal-on-metal articulations while placing these complications into the context of failures associated with all hip arthroplasties. This novel clinical information should be valuable for the practicing surgeon faced with this patient population.

Level of Evidence

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

OBJECTIVE: To study the rates of use of total hip arthroplasty (THA) and total knee arthroplasty (TKA) during the past 4 decades.

METHODS: The Rochester Epidemiology Project was used to identify all Olmsted County, Minnesota, residents who underwent THA or TKA from January 1, 1969, through December 31, 2008. We used a population-based approach because few data are available on long-term trends in the use of THA and TKA in the United States. Rates of use were determined by age- and sex-specific person-years at risk. Poisson regression was used to assess temporal trends by sex and age group.

RESULTS: The age- and sex-adjusted use of THA increased from 50.2 (95% confidence interval [CI], 40.5-59.8) per 100,000 person-years in 1969-1972 to 145.5 (95% CI, 134.2-156.9) in 2005-2008, whereas TKA increased markedly from 31.2 (95% CI, 25.3-37.1) per 100,000 person-years in 1971-1976 to 220.9 (95% CI, 206.7-235.0) in 2005-2008. For both procedures, use was greater among females, and the rate generally increased with age.

CONCLUSION: In this community, TKA and THA use rates have increased steadily since the introduction of the procedures and continue to increase for all age groups. On the basis of these population-based data, the probable need for TKA and THA exceeds current federal agency projections.

In Olmsted County, Minnesota, use rates of total hip arthroplasty and total knee arthroplasty have increased steadily since introduction of the procedures and continue to increase for all age groups.

Background

To address the long-term problems of bearing surface wear and osteolysis associated with conventional metal-polyethylene (M-PE) total hip arthroplasty (THA), metal-metal (M-M), and ceramic-ceramic (C-C) bearings have been introduced. These bearing surfaces are associated with unique risks and benefits and higher costs. However the relative risks of these three bearings in an older population is unknown.

Questions/purposes

We compared the short-term risk of complication and revision THA among Medicare patients having a primary THA with metal-polyethylene (M-PE), metal-metal (M-M), and ceramic-ceramic (C-C) bearings.

Methods

We used the 2005 to 2007 100% Medicare inpatient claim files to perform a matched cohort analysis in three separate cohorts of THA patients (M-PE, M-M, and C-C) who were matched by age, gender, and US census region. Multivariate Cox proportional-hazards models were constructed to compare complication and revision THA risk among cohorts, adjusting for medical comorbidities, race, socioeconomic status, and hospital factors.

Results

After adjusting for patient and hospital factors, M-M bearings were associated with a higher risk of periprosthetic joint infection (hazard ratio, 3.03; confidence interval, 1.02–9.09) when compared with C-C bearings (0.59% versus 0.32%, respectively). There were no other differences among bearing cohorts in the adjusted risk of revision THA or any other complication.

Conclusions

The risk of short-term complication (including dislocation) and revision THA were similar among appropriately matched Medicare THA patients regardless of bearing surface. Hard-on-hard THA bearings are of questionable value in Medicare patients, given the higher cost associated with their use and uncertain long-term benefits in older patients.

Level of Evidence

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background

To address the long-term problems of bearing surface wear and osteolysis associated with conventional metal-polyethylene (M-PE) total hip arthroplasty (THA), metal-metal (M-M), and ceramic-ceramic (C-C) bearings have been introduced. These bearing surfaces are associated with unique risks and benefits and higher costs. However the relative risks of these three bearings in an older population is unknown.

Questions/purposes

We compared the short-term risk of complication and revision THA among Medicare patients having a primary THA with metal-polyethylene (M-PE), metal-metal (M-M), and ceramic-ceramic (C-C) bearings.

Methods

We used the 2005 to 2007 100% Medicare inpatient claim files to perform a matched cohort analysis in three separate cohorts of THA patients (M-PE, M-M, and C-C) who were matched by age, gender, and US census region. Multivariate Cox proportional-hazards models were constructed to compare complication and revision THA risk among cohorts, adjusting for medical comorbidities, race, socioeconomic status, and hospital factors.

Results

After adjusting for patient and hospital factors, M-M bearings were associated with a higher risk of periprosthetic joint infection (hazard ratio, 3.03; confidence interval, 1.02–9.09) when compared with C-C bearings (0.59% versus 0.32%, respectively). There were no other differences among bearing cohorts in the adjusted risk of revision THA or any other complication.

Conclusions

The risk of short-term complication (including dislocation) and revision THA were similar among appropriately matched Medicare THA patients regardless of bearing surface. Hard-on-hard THA bearings are of questionable value in Medicare patients, given the higher cost associated with their use and uncertain long-term benefits in older patients.

Level of Evidence

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Most reports on two-stage reimplantation have focused on the short-term cure rate of infection, but little is known about long-term reinfection-free survival or mechanical durability. We retrospectively reviewed 168 patients (169 hips) with infected arthroplasty, all of whom had two-stage reimplantation for the treatment of an infected total hip arthroplasty between 1988 and 1998. In the second stage, the femoral component was fixed with antibiotic-loaded bone cement in 121 hips; the remaining femoral components and all acetabular components were uncemented. The minimum followup time was 2 years (mean, 7 years; range, 2–16 years). At most recent followup, 12 hips (7.1%) were reoperated on for reinfection and 13 hips (7.7%) were revised for aseptic loosening or osteolysis. Apparently aseptic loosening occurred on one or both sides of the joint in 24 hips (14.2%). The 10-year survivals free of reinfection and mechanical failure were 87.5% and 75.2% respectively. Nineteen hips dislocated and eight underwent revision surgery for instability. The method of femoral component fixation, either with or without cement, did not correlate with risk of infection, loosening, or mechanical failure. Based on these results, the method of fixation used for the femoral component during two-stage reimplantation surgery should be based on the surgeon’s preference for fixation combined with the assessment of femoral bone stock.

Level of Evidence: Level IV, case series. See the Guidelines for Authors for a complete description of levels of evidence.

Most computer navigation systems used in total hip arthroplasty integrate preoperative pelvic tilt to calculate the anterior pelvic plane assuming tilt is constant; however, the consistency of pelvic tilt after THA has never been proven. Therefore, using a modern comprehensive gait analysis before and after arthroplasty we sought to compare (1) dynamic pelvic tilt changes and (2) pelvic flexion/extension range-of-motion changes. Twenty-one patients who underwent unilateral THA were prospectively studied. Quantitative pelvic tilt changes (in the sagittal plane) and pelvic range of flexion/extension motion relative to a laboratory coordinate system were compared using a computerized video motion system. Mean gait pelvic tilt was 13.9º ± 4.8º (range, 1.73º–23.1º) preoperatively, 12.5º ± 4.5º (range, 1.4º–18.7º) 2 months postoperatively, and 10.5° ± 5.5º (range, –2.36º–19.2º) 12 months postoperatively. A significant proportion (31%) of patients had more than a 5° difference between preoperative and 12-month postoperative measurements and the variability was spread over 20°. Significant dynamic changes in pelvic tilt occurred after THA. While navigation clearly improves the anatomical position of the component during THA, the functional position of the component will not always be improved because of the significant change between preoperative and postoperative pelvic tilt.

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.

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.