Thomas Barber

An analysis of the risk of hip dislocation with a contemporary total joint registry.

Dislocation rates after total hip arthroplasty in a community setting have not been well documented. We used a community based joint registry to evaluate hip dislocations that occurred within 1 year after total hip arthroplasty. We evaluated patient, implant, and technical factors associated with dislocation, including primary versus revision surgery, femoral head size (28 mm versus ≥ 32 mm), operative time, surgeon volume, surgical approach, age, gender, diagnosis, American Society of Anesthesiologists (ASA) classification, and body mass index (BMI). There were 1693 primary total hip arthroplasties and 277 revision procedures performed from 2001-2003. The overall dislocation rate was 1.7% for primary total hip arthroplasties and 5.1% for revision procedures. Patients with ASA scores of 3 or 4 had a 2.3-fold dislocation increase compared with patients with scores of 1 or 2. Patients with rheumatoid arthritis had an increased risk of dislocation. The dislocation rates for primary total hip arthroplasty were 2% for 28 mm heads and 0.7% for heads ≥ 32 mm. The surgeons patient volume, surgical approach, operative time, and body mass index had no effect on dislocation.Level of Evidence: Prognostic study, level III. See Guidelines for Authors for a complete description of levels of evidence.

The International Consortium of Orthopaedic Registries: Overview and Summary

FDA Post-Market Efforts and Interest in Orthopaedics The United States Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH) monitors both mandatory and voluntary post-market reporting to identify adverse events and problems associated with medical devices. Although the manufacturers of medical devices are required to report deaths, injuries, and malfunctions directly to the FDA, the device users are required to report these events to the manufacturer and are required to report only deaths to the FDA. Voluntary reporting systems such as the MedWatch program, the MAUDE (Manufacturer and User Facility Device Experience) database, and the MedSun (Medical Product Safety Network) enhanced surveillance network provide nationwide medical device surveillance in the U.S. However, these reporting systems have important weaknesses, such as incomplete, inaccurate, or nonvalidated data, reporting biases related to event severity, concerns that reporting may result in adverse publicity or litigation, and general underreporting of events. Most importantly, denominator data are missing, which makes evaluation of the incidence or prevalence of a safety-related event impossible. The FDA’s interest in orthopaedic device safety and in the development of infrastructure for enhanced safety monitoring is natural and timely; the lack of such safety evidence is particularly troubling for the most commonly used implants. Over 700,000 joint replacements involving implantable devices are conducted annually in the U.S. alone, and the annual volume is projected to increase twofold for hip joint replacements and sevenfold for knee joint replacements, to a total of more than 3 million annually, in just the next twenty years. Moreover, these surgical procedures are expected to become more expensive, with costs tripling in just the next five years. Despite remarkable advancements in orthopaedics, including new devices and improved surgical techniques, the value of many therapeutic devices has not been established in clinical trials or in real-world settings. Several factors contribute to this shortcoming: (1) rapidly changing device technology coupled with an enormous number of devices on the market; (2) the need for large numbers of patients and long-term follow-up to adequately evaluate the primary safety end point, which is longterm device failure or need for revision; and (3) the need for prospective data collection, planning, and substantial funding to evaluate short and long-term patient-reported outcomes, which are the primary effectiveness end points. The poor state of research and the resulting inability to learn about a device’s benefits, its potential harms, and the balance between them hinder decision-making by the FDA and other stakeholders such as the Centers for Medicare & Medicaid Services (CMS) and commercial insurers.

Kaiser Permanente Implant Registries Benefit Patient Safety, Quality Improvement, Cost-Effectiveness

BACKGROUND In response to the increased volume, risk, and cost of medical devices, in 2001 Kaiser Permanente (KP) developed implant registries to enhance patient safety and quality, and to evaluate cost-effectiveness. METHODS Using an integrated electronic health record system, administrative databases, and other institutional databases, orthopedic, cardiology, and vascular implant registries were developed in 2001, 2006, and 2011, respectively. These registries monitor patients, implants, clinical practices, and surgical outcomes for KPs 9 million members. Critical to registry success is surgeon leadership and engagement; each geographical region has a surgeon champion who provides feedback on registry initiatives and disseminates registry findings. RESULTS The registries enhance patient safety by providing a variety of clinical decision tools such as risk calculators, quality reports, risk-adjusted medical center reports, summaries of surgeon data, and infection control reports to registry stakeholders. The registries are used to immediately identify patients with recalled devices, evaluate new and established device technology, and identify outlier implants. The registries contribute to cost-effectiveness initiatives through collaboration with sourcing and contracting groups and confirming adherence to device formulary guidelines. Research studies based on registry data have directly influenced clinical best practices. CONCLUSIONS Registries are important tools to evaluate longitudinal device performance and safety, study the clinical indications for and outcomes of device implantation, respond promptly to recalls and advisories, and contribute to the overall high quality of care of our patients.

Bariatric surgery prior to total joint arthroplasty may not provide dramatic improvements in post-arthroplasty surgical outcomes.

This study compared the total joint arthroplasty (TJA) surgical outcomes of patients who had bariatric surgery prior to TJA to TJA patients who were candidates but did not have bariatric surgery. Patients were retrospectively grouped into: Group 1 (n = 69), those with bariatric surgery >2 years prior to TJA, Group 2 (n = 102), those with surgery within 2 years of TJA, and Group 3 (n = 11,032), those without bariatric surgery. In Group 1, 2.9% (95% CI 0.0-6.9%) had complications within 1 year compared to 5.9% (95% CI 1.3%-10.4%) in Group 2, and 4.1% (95% CI 3.8%-4.5%) in Group 3. Ninety-day readmission (7.2%, 95% CI 1.1%-13.4%) and revision density (3.4/100 years of observation) was highest in Group 1. Bariatric surgery prior to TJA may not provide dramatic improvements in post-operative TJA surgical outcomes.

Defining an International Standard Set of Outcome Measures for Patients With Hip or Knee Osteoarthritis: Consensus of the International Consortium for Health Outcomes Measurement Hip and Knee Osteoarthritis Working Group

To define a minimum Standard Set of outcome measures and case‐mix factors for monitoring, comparing, and improving health care for patients with clinically diagnosed hip or knee osteoarthritis (OA), with a focus on defining the outcomes that matter most to patients.

Risk Calculators Predict Failures of Knee and Hip Arthroplasties: Findings from a Large Health Maintenance Organization

BackgroundConsidering the cost and risk associated with revision Total knee arthroplasty (TKAs) and Total hip arthroplasty (THAs), steps to prevent these operations will help patients and reduce healthcare costs. Revision risk calculators for patients may reduce revision surgery by supporting clinical decision-making at the point of care.Questions/purposesWe sought to develop a TKA and THA revision risk calculator using data from a large health-maintenance organization’s arthroplasty registry and determine the best set of predictors for the revision risk calculator.MethodsRevision risk calculators for THAs and TKAs were developed using a patient cohort from a total joint replacement registry and data from a large US integrated healthcare system. The cohort included all patients who had primary procedures performed in our healthcare system between April 2001 and July 2008 and were followed until January 2014 (TKAs, n = 41,750; THAs, n = 22,721), During the study period, 9% of patients (TKA = 3066/34,686; THA=1898/20,285) were lost to followup and 7% died (TKA= 2350/41,750; THA=1419/20,285). The outcome of interest was revision surgery and was defined as replacement of any component for any reason within 5 years postoperatively. Candidate predictors for the revision risk calculator were limited to preoperative patient demographics, comorbidities, and procedure diagnoses. Logistic regression models were used to identify predictors and the Hosmer-Lemeshow goodness-of-fit test and c-statistic were used to choose final models for the revision risk calculator.ResultsThe best predictors for the TKA revision risk calculator were age (odds ratio [OR], 0.96; 95% CI, 0.95–0.97; p < 0.001), sex (OR, 0.84; 95% CI, 0.75–0.95; p = 0.004), square-root BMI (OR, 1.05; 95% CI, 0.99–1.11; p = 0.140), diabetes (OR, 1.32; 95% CI, 1.17–1.48; p < 0.001), osteoarthritis (OR, 1.16; 95% CI, 0.84–1.62; p = 0.368), posttraumatic arthritis (OR, 1.66; 95% CI, 1.07–2.56; p = 0.022), and osteonecrosis (OR, 2.54; 95% CI, 1.31–4.92; p = 0.006). The best predictors for the THA revision risk calculator were sex (OR, 1.24; 95% CI, 1.05–1.46; p = 0.010), age (OR, 0.98; 95% CI, 0.98–0.99; p < 0.001), square-root BMI (OR, 1.07; 95% CI, 1.00–1.15; p = 0.066), and osteoarthritis (OR, 0.85; 95% CI, 0.66–1.09; p = 0.190).ConclusionsStudy model parameters can be used to create web-based calculators. Surgeons can enter personalized patient data in the risk calculators for identification of risk of revision which can be used for clinical decision making at the point of care. Future prospective studies will be needed to validate these calculators and to refine them with time.Level of EvidenceLevel III, prognostic study.

Multinational Comprehensive Evaluation of the Fixation Method Used in Hip Replacement: Interaction with Age in Context

BACKGROUND Fixation in total hip replacements remains a controversial topic, despite the high level of its success. Data obtained from major orthopaedic registries indicate that there are large differences among preferred fixation and survival results. METHODS Using a distributed registry data network, primary total hip arthroplasties performed for osteoarthritis from 2001 to 2010 were identified from six national and regional total joint arthroplasty registries. A multivariate meta-analysis was performed using linear mixed models with the primary outcome revision for any reason. Survival probabilities and their standard errors were extracted from each registry for each unique combination of the covariates. Fixation strategies were compared with regard to age group, sex, bearing, and femoral-head diameter. All comparisons were based on the random-effects model and the fixed-effects model. RESULTS In patients who were seventy-five years of age and older, uncemented fixation had a significantly higher risk of revision (p < 0.001) than hybrid fixation, with a hazard ratio of 1.575 (95% confidence interval, 1.389 to 1.786). We found a similar, if lesser, effect in the intermediate age group of sixty-five to seventy-four years (hazard ratio, 1.16 [95% confidence interval, 1.023 to 1.315]; p = 0.021) and in the younger age group of forty-five to sixty-four years (hazard ratio, 1.205 [95% confidence interval, 1.008 to 1.442]; p = 0.041). There were no significant differences between hybrid and cemented bearings across age groups. CONCLUSIONS We conclude that cementless fixation should be avoided in older patients (those seventy-five years of age or older), although this evidence is less strong in patients of intermediate and younger ages.

Effect of Femoral Head Size on Metal-on-HXLPE Hip Arthroplasty Outcome in a Combined Analysis of Six National and Regional Registries

BACKGROUND HXLPE (highly cross-linked polyethylene) has greater wear resistance compared with UHMWPE (ultra-high molecular weight polyethylene), which may contribute to improving the outcomes of total hip arthroplasty with a large femoral head. However, no information is available regarding the effect of femoral head size on the survivorship of HXLPE hip prostheses. The aim of the present study was to provide evidence regarding whether femoral head size has an effect on the risk of revision when an HXLPE liner is used on a metal head. METHODS A distributed health data network was developed by the ICOR (International Consortium of Orthopaedic Registries). Six national and regional registries are participating in this network: Kaiser Permanente, HealthEast, the Emilia-Romagna region in Italy, the Catalan region in Spain, Norway, and Australia. Data from each registry were standardized and provided at an aggregate level for each of the variables of interest. Patients with osteoarthritis who were forty-five to sixty-four years of age and had undergone uncemented total hip arthroplasty were included in the present study. Analyses were performed on the basis of individual patient profiles, utilizing the variables collected from each registry. The outcome of interest was the time to the first revision (for any reason). Survival probabilities and their standard errors were extracted from each registry for each unique combination of the covariates and were combined through multivariate meta-analysis utilizing linear mixed models to compare survivorship for <32-mm, 32-mm, and >32-mm femoral head sizes. RESULTS A total of 14,372 total hip arthroplasties were included in the study. The five-year rate of revision surgery varied from 1.9% to 3.2% among registries. The risk of revision did not differ significantly between <32-mm and 32-mm head sizes (HR [hazard ratio] = 0.91, 95% CI [confidence interval] = 0.69 to 1.19) or between >32-mm and 32-mm sizes (HR = 1.05, 95% CI = 0.70 to 1.55). CONCLUSIONS The results of our study provide relevant data to orthopaedic surgeons deciding on the use of a larger articulation in a metal-on-polyethylene bearing. A larger head diameter should not be considered a detriment to device survival when an HXLPE liner is used. However, efforts to force the use of a large-size implant appear unsupported, as similar survivorship was observed for all head diameter groups.

Comparative effectiveness of ceramic-on-ceramic implants in stemmed hip replacement: A multinational study of six national and regional registries

BACKGROUND The rapid decline in use of conventional total hip replacement with a large femoral head size and a metal-on-metal bearing surface might lead to increased popularity of ceramic-on-ceramic bearings as another hard-on-hard alternative that allows implantation of a larger head. We sought to address comparative effectiveness of ceramic-on-ceramic and metal-on-HXLPE (highly cross-linked polyethylene) implants by utilizing the distributed health data network of the ICOR (International Consortium of Orthopaedic Registries), an unprecedented collaboration of national and regional registries and the U.S. FDA (Food and Drug Administration). METHODS A distributed health data network was developed by the ICOR and used in this study. The data from each registry are standardized and provided at a level of aggregation most suitable for the detailed analysis of interest. The data are combined across registries for comprehensive assessments. The ICOR coordinating center and study steering committee defined the inclusion criteria for this study as total hip arthroplasty performed without cement from 2001 to 2010 in patients forty-five to sixty-four years of age with osteoarthritis. Six national and regional registries (Kaiser Permanente and HealthEast in the U.S., Emilia-Romagna region in Italy, Catalan region in Spain, Norway, and Australia) participated in this study. Multivariate meta-analysis was performed with use of linear mixed models, with survival probability as the unit of analysis. We present the results of the fixed-effects model and include the results of the random-effects model in an appendix. SAS version 9.2 was used for all analyses. We first compared femoral head sizes of >28 mm and ≤28 mm within ceramic-on-ceramic implants and then compared ceramic-on-ceramic with metal-on-HXLPE. RESULTS A total of 34,985 patients were included; 52% were female. We found a lower risk of revision associated with use of ceramic-on-ceramic implants when a larger head size was used (HR [hazard ratio] = 0.73, 95% CI [confidence interval] = 0.60 to 0.88, p = 0.001). Use of smaller-head-size ceramic-on-ceramic bearings was associated with a higher risk of failure compared with metal-on-HXLPE bearings (HR = 1.36, 95% CI = 1.09 to 1.68, p = 0.006). Use of large-head-size ceramic-on-ceramic bearings was associated with a small protective effect relative to metal-on-HXLPE bearings (not subdivided by head size) in years zero to two, but this difference dissipated over the longer term. CONCLUSIONS Our multinational study based on a harmonized, distributed network showed that use of ceramic-on-ceramic implants with a smaller head size in total hip arthroplasty without cement was associated with a higher risk of revision compared with metal-on-HXLPE and >28-mm ceramic-on-ceramic implants. These findings warrant careful reflection by regulatory and clinical communities and wide dissemination to patients for informed decision-making regarding such surgery.

Total joint replacement: A multiple risk factor analysis of physical activity level 1-2 years postoperatively.

Background and purpose — The effect of total joint arthroplasty (TJA) on physical activity is not fully understood. We investigated the change in physical activity after TJA and patient factors associated with change. Patients and methods — Using a total joint replacement registry, primary total hip arthroplasty (THA) patients (n = 5,678) and knee arthroplasty (TKA) patients (n = 11,084) between January 1, 2010 and December 31, 2012 were identified. Median age at THA was 68 and median age at TKA was 67. Change in self-reported physical activity (minutes per week) from before TJA (within 1 year of surgery) to after TJA (1–2 years) was the outcome of interest. Patient demographics and comorbidities were evaluated as risk factors. Multiple linear regression was used. Results — Median physical activity before surgery was 50 min/week (IQR: 0–140) for THA patients and 58 (IQR: 3–143) for TKA patients. Median physical activity after surgery was 150 min/week (IQR: 60–280) for both THA patients and TKA patients. Following TJA, 50% of patients met CDC/WHO physical activity guideline criteria. Higher body mass index was associated with lower change in physical activity (THA: −7.1 min/week; TKA: −5.9 min/week). Females had lower change than males (THA: −11 min/week; TKA: −9.1 min/week). In TKA patients, renal failure was associated with lower change (−17 min/week), as were neurological disorders (−30 min/week). Interpretation — Self-reported minutes of physical activity increased from before to after TJA, but 50% of TJA patients did not meet recommended physical activity guideline criteria. Higher body mass index, female sex, and specific comorbidities were found to be associated with low change in physical activity. Patient education on the benefits of physical activity should concentrate on these subgroups of patients.