A Scandinavian experience of register collaboration: the Nordic Arthroplasty Register Association (NARA)

Increasing femoral head size from 32 mm to 36 mm does not increase the revision risk for total hip replacement: a New Zealand joint registry study

BACKGROUND

The use of larger femoral heads in total hip replacement (THR) has increased over the last decade. While the relationship between increasing head size and increased stability is well known, the risk of revision with increasing head size remains poorly understood. The aim of this study was to compare the outcome of total hip joint replacement with 32-mm and 36-mm heads.

METHODS

We carried out a 20-year retrospective analysis of prospective data from the New Zealand Joint Registry (NZJR). All primary total hip replacements registered between January 1999 and December 2018 were included. We compared the rate of revision of 32-mm and 36-mm heads in THR. Sub-group analysis included comparisons of bearing type and all-cause revision.

RESULTS

60,051 primary THRs met our inclusion criteria. The revision rate per 100 component years was significantly higher with a 36-mm head than with a 32-mm head (0.649 vs. 0.534, p < 0.001). Subgroup analysis of bearing type showed no significant differences in revision rates for all combinations of 36-mm heads when compared to 32-mm (p = 0.074-0.92), with the exception of metal-on-metal (MoM); p = 0.038. When MoM was removed there was no significant difference in revision rates per 100 component years between 32-mm and 36-mm heads, 0.528 versus 0.578 (p = 0.099).

CONCLUSIONS

Increasing head size from 32 mm to 36 mm results in no significant increase in revision in all bearing combinations except MoM.

Risk of revision arthroplasty surgery after exposure to physically demanding occupational or leisure activities: A systematic review

INTRODUCTION

Lower limb arthroplasty is successful at relieving symptoms associated with joint failure. However, physically-demanding activities can cause primary osteoarthritis and accordingly such exposure post-operatively might increase the risk of prosthetic failure. Therefore, we systematically reviewed the literature to investigate whether there was any evidence of increased risk of revision arthroplasty after exposure to intensive, physically-demanding activities at work or during leisure-time.

METHODS

We searched Medline, Embase and Scopus databases (1985-July 2021) for original studies including primary lower limb arthroplasty recipients that gathered information on physically-demanding occupational and/or leisure activities and rates of revision arthroplasty. Methodological assessment was performed independently by two assessors using SIGN, AQUILA and STROBE. The protocol was registered in PROSPERO [CRD42017067728].

RESULTS

Thirteen eligible studies were identified: 9 (4,432 participants) after hip arthroplasty and 4 (7,137participants) after knee arthroplasty. Narrative synthesis was performed due to considerable heterogeneity in quantifying exposures. We found limited evidence that post-operative activities (work or leisure) did not increase the risk of knee revision and could even be protective. We found insufficient high-quality evidence to indicate that exposure to physically-demanding occupations increased the risk of hip revision although "heavy work", agricultural work and, in women, health services work, may be implicated. We found conflicting evidence about risk of revision hip arthroplasty associated with either leisure-time or total physical activities (occupational or leisure-time).

CONCLUSION

There is currently a limited evidence base to address this important question. There is weak evidence that the risk of revision hip arthroplasty may be increased by exposure to physically-demanding occupational activities but insufficient evidence about the impact on knee revision and about exposure to leisure-time activities after both procedures. More evidence is urgently needed to advise lower limb arthroplasty recipients, particularly people expecting to return to jobs in some sectors (e.g., construction, agriculture, military).

Variation and trends in reasons for knee replacement revision: a multi-registry study of revision burden

Background and purpose - Studies describing time-related change in reasons for knee replacement revision have been limited to single regions or institutions, commonly analyze only 1st revisions, and may not reflect true caseloads or findings from other areas. We used revision procedure data from 3 arthroplasty registries to determine trends and differences in knee replacement revision diagnoses.Patients and methods - We obtained aggregated data for 78,151 revision knee replacement procedures recorded by the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) for the period 2003-2017. Equivalent diagnosis groups were created. We calculated the annual proportions of the most common reasons for revision.Results - Infection, loosening, and instability were among the 5 most common reasons for revision but magnitude and ranking varied between registries. Over time there were increases in proportions of revisions for infection and decreases in revisions for wear. There were inconsistent proportions and trends for the other reasons for revision. The incidence of revision for infection showed a uniform increase.Interpretation - Despite some differences in terminology, comparison of registry-recorded revision diagnoses is possible, but defining a single reason for revision is not always clear-cut. There were common increases in revision for infection and decreases in revision for wear, but variable changes in other categories. This may reflect regional practice differences and therefore generalizability of studies regarding reasons for revision is unwise.

Total hip arthroplasties in the Dutch Arthroplasty Register (LROI) and the Nordic Arthroplasty Register Association (NARA): comparison of patient and procedure characteristics in 475,685 cases

Background and purpose - Collaborations between arthroplasty registries are important in order to create the possibility of detecting inferior implants early and improve our understanding of differences between nations in terms of indications and outcomes. In this registry study we compared patient and procedure characteristics, and revision rates in the Nordic Arthroplasty Register Association (NARA) database and the Dutch Arthroplasty Register (LROI).Patients and methods - All total hip arthroplasties (THAs) performed in 2010-2016 were included from the LROI (n = 184,862) and the NARA database (n = 290,823), which contains data from Denmark, Norway, Sweden, and Finland. Descriptive statistics and Kaplan-Meier survival analyses based on all reasons for revision and stratified by fixation were performed and compared between countries.Results - In the Netherlands, the proportion of patients aged < 55 years (9%) and male patients (34%) was lower than in Nordic countries (< 55 years 11-13%; males 35-43%); the proportion of osteoarthritis (OA) (87%) was higher compared with Sweden (81%), Norway (77%), and Denmark (81%) but comparable to Finland (86%). Uncemented fixation was used in 62% of patients in the Netherlands, in 70% of patients in Denmark and Finland, and in 28% and 19% in Norway and Sweden, respectively. The 5-year revision rate for THAs for OA was lower in Sweden (2.3%, 95% CI 2.1-2.5) than in the Netherlands (3.0%, CI 2.9-3.1), Norway (3.8%, CI 3.6-4.0), Denmark (4.6%, CI 4.4-4.8), and Finland (4.4%, CI 4.3-4.5). Revision rates in Denmark, Norway, and Finland were higher for all fixation groups.Interpretation - Patient and THA procedure characteristics as well as revision rates evinced some differences between the Netherlands and the Nordic countries. The Netherlands compared best with Denmark in terms of patient and procedure characteristics, but resembled Sweden more in terms of short-term revision risk. Combining data from registries like LROI and the NARA collaboration is feasible and might possibly enable tracking of potential outlier implants.

Is there a reduction in risk of revision when 36-mm heads instead of 32 mm are used in total hip arthroplasty for patients with proximal femur fractures?

Background and purpose - 32-mm heads are widely used in total hip arthroplasty (THA) in Scandinavia, while the proportion of 36-mm heads is increasing as they are expected to increase THA stability. We investigated whether the use of 36-mm heads in THA after proximal femur fracture (PFF) is associated with a lower risk of revision compared with 32-mm heads.Patients and methods - We included 5,030 patients operated with THA due to PFF with 32- or 36-mm heads from the Nordic Arthroplasty Register Association database. Each patient with a 36-mm head was matched with a patient with a 32-mm head, using propensity score. The patients were operated between 2006 and 2016, with a metal or ceramic head on a polyethylene bearing. Cox proportional hazards models were fitted to estimate the unadjusted and adjusted hazard ratio (HR) with 95% confidence intervals (CI) for revision for any reason and revision due to dislocation for 36-mm heads compared with 32-mm heads.Results - 36-mm heads had an HR of 0.9 (CI 0.7-1.2) for revision for any reason and 0.8 (CI 0.5-1.3) for revision due to dislocation compared with 32-mm heads at a median follow-up of 2.5 years (interquartile range 1-4.4).Interpretation - We were not able to demonstrate any clinically relevant reduction of the risk of THA revision for any reason or due to dislocation when 36-mm heads were used versus 32-mm. Residual confounding due to lack of data on patient comorbidities and body mass index could bias our results.

Global trends in indications for total elbow arthroplasty: a systematic review of national registries

National registries provide useful information in understanding outcomes of surgeries that have late sequelae, especially for rare operations such as total elbow arthroplasty (TEA).A systematic search was performed and data were compiled from the registries to compare total elbow arthroplasty outcomes and evaluate trends. We included six registries from Australia, the Netherlands, New Zealand, Norway, the United Kingdom and Sweden.Inflammatory arthritis was the most common indication for total elbow arthroplasty, followed by acute fracture and osteoarthritis. When comparing 2000-2009 to 2010-2017 data, total elbow arthroplasty for inflammatory arthritis decreased and total elbow arthroplasty for fracture and osteoarthritis increased. There was an increase in the number of revision TEAs over this time period.The range of indications for total elbow arthroplasty is broadening; total elbow arthroplasty for acute trauma and osteoarthritis is becoming increasingly more common. However, inflammatory arthritis remains the most common indication in recent years. This change is accompanied by an increase in the incidence of revision surgery. Cite this article: EFORT Open Rev 2020;5:215-220. DOI: 10.1302/2058-5241.5.190036.

A comparison of the minimum data sets for primary shoulder arthroplasty between national shoulder arthroplasty registries. Is international harmonization feasible?

The aims of this study were to identify the common components of the Minimum Data Set (MDS) of current national shoulder arthroplasty registries that could be pooled for analysis; and to determine whether further harmonisation of data collection across these registries would be feasible. Copies of primary shoulder arthroplasty MDS forms, annual reports, and other publications from national shoulder arthroplasty registries were identified using internet search engines up to November 2016. Data relating to local or regional registries was excluded. There were nine national shoulder arthroplasty registries reporting a total of 97,388 primary shoulder replacements. All minimum data sets included patient identifiers, date of surgery, implant identification, laterality of surgery, indication and mode of implant fixation. At least 6 registries had common options within the categories of indication, implant fixation and previous operations. Most discrepancies were seen in categories for additional interventions, outcome measures, and intra-operative complications. As numbers within individual registries are relatively small, international collaboration would harness the global strength of knowledge and experience in shoulder replacement. Several similarities were identified between the current national registries that could become unified with only minor changes by a few registries, highlighting the potential feasibility of MDS harmonisat.

The what, when and how of orthopaedic registers: an introduction into register-based research

Establishment of orthopaedic registers started in 1975 and many registers have been initiated since. The main purpose of registers is to collect information on patients, implants and procedures in order to monitor and improve the outcome of the specific procedure.

Data validity reflects the quality of the registered data and consists of four major aspects: coverage of the register, registration completeness of procedures/patients, registration completeness of variables included in the register and accuracy of registered variables.

Survival analysis is often used in register studies to estimate the incidence of an outcome. The most commonly used survival analysis is the Kaplan–Meier survival curves, which present the proportion of patients who have not experienced the defined event (e.g. death or revision of a prosthesis) in relation to the time. Depending on the research question, competing events can be taken into account by using the cumulative incidence function. Cox regression analysis is used to compare survival data for different groups taking differences between groups into account.

When interpreting the results from observational register-based studies a number of factors including selection bias, information bias, chance and confounding have to be taken into account. In observational register-based studies selection bias is related to, for example, absence of complete follow-up of the patients, whereas information bias is related to, for example, misclassification of exposure (e.g. risk factor of interest) or/and outcome.

The REporting of studies Conducted using Observational Routinely-collected Data guidelines should be used for studies based on routinely-collected health data including orthopaedic registers.

Linkage between orthopaedic registers, other clinical quality databases and administrative health registers may be of value when performing orthopaedic register-based research.

Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180097

An international comparison of THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States

Background and purpose - International comparisons of total hip arthroplasty (THA) practices and outcomes provide an opportunity to enhance the quality of care worldwide. We compared THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States. Patients and methods - Primary THAs due to osteoarthritis were identified using Swedish (n = 159,695), Australian (n = 279,693), and US registries (n = 69,641) (2003-2015). We compared patients, practices, and implant usage across the countries using descriptive statistics. We evaluated time to all-cause revision using Kaplan-Meier survival curves. We assessed differences in countries' THA survival using chi-square tests of survival probabilities. Results - Sweden had fewer comorbidities than the United States and Australia. Cement fixation was used predominantly in Sweden and cementless in the United States and Australia. The direct anterior approach was used more frequently in the United States and Australia. Smaller head sizes (≤ 32 mm vs. ≥ 36 mm) were used more often in Sweden than the United States and Australia. Metal-on-highly cross-linked polyethylene was used more frequently in the United States and Australia than in Sweden. Sweden's 5- (97.8%) and 10-year THA survival (95.8%) was higher than the United States' (5-year: 97.0%; 10-year: 95.2%) and Australia (5-year: 96.3%; 10-year: 93.5%). Interpretation - Patient characteristics, surgical techniques, and implants differed across the 3 countries, emphasizing the need to adjust for demographics, surgical techniques, and implants and the need for global standardized definitions to compare THA survivorship internationally.

Dual Mobility Cups: Effect on Risk of Revision of Primary Total Hip Arthroplasty Due to Osteoarthritis: A Matched Population-Based Study Using the Nordic Arthroplasty Register Association Database

BACKGROUND

The dual mobility acetabular cup (DMC) was designed to reduce prosthetic instability and has gained popularity for both primary and revision total hip arthroplasty (THA). We compared the risk of revision of primary THA for primary osteoarthritis between patients treated with a DMC and those who received a metal-on-polyethylene (MoP) or ceramic-on-polyethylene (CoP) bearing.

METHODS

A search of the Nordic Arthroplasty Register Association (NARA) database identified THAs performed with a DMC during 1995 to 2013. With use of propensity score matching, 2,277 of these patients were matched (1:1), with regard to sex, age, component fixation, and year of surgery, with patients with an MoP or CoP bearing. We estimated the cumulative incidence of revision taking death as a competing risk into consideration and performed competing risk regression with revision or death as end points.

RESULTS

There was no difference in the overall risk of revision between the DMC group and the propensity-score-matched MoP/CoP group (adjusted hazard ratio [HR] = 1.18; 95% confidence interval [95% CI] = 0.87 to 1.62). Patients with a DMC bearing had a lower risk of revision due to dislocation (adjusted HR = 0.09; 95% CI = 0.03 to 0.29) but a higher risk of revision caused by infection (adjusted HR = 3.20; 95% CI = 1.49 to 6.85).

CONCLUSIONS

There was no difference in overall risk of revision between the DMC and MoP/CoP groups. The DMCs protected against revision due to dislocation but THAs performed with this bearing were more commonly revised because of infection. There may have been a selection bias toward placing DMC implants in patients with greater frailty as the mortality rates were higher in the DMC group than in the age and sex-matched MoP/CoP group.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

No Increase in Survival for 36-mm versus 32-mm Femoral Heads in Metal-on-polyethylene THA: A Registry Study

BACKGROUND

During the past decade, the 32-mm head has replaced the 28-mm head as the most common head size used in primary THA in many national registries, and the use of 36-mm heads has also increased. However, it is unclear whether 32-mm and 36-mm heads decrease the revision risk in metal-on-polyethylene (MoP) THA compared with 28-mm heads.

QUESTIONS/PURPOSES

(1) In the setting of the Nordic Arthroplasty Register Association database, does the revision risk for any reason differ among 28-, 32-, and 36-mm head sizes in patients undergoing surgery with MoP THA? (2) Does the revision risk resulting from dislocation decrease with increasing head diameter (28-36 mm) in patients undergoing surgery with MoP THA in the same registry?

METHODS

Data were derived from the Nordic Arthroplasty Register Association database, a collaboration among the national arthroplasty registries of Denmark, Finland, Norway, and Sweden. Patients with primary osteoarthritis who had undergone primary THA with a 28-, 32-, or 36-mm MoP bearing from 2003 to 2014 were included. Patients operated on with dual-mobility cups were excluded. In patients with bilateral THA, only the first operated hip was included. After applying the inclusion criteria, the number of patients and THAs with a complete data set was determined to be 186,231, which accounted for 51% of all hips (366,309) with primary osteoarthritis operated on with THA of any head size and bearing type during the study observation time. Of the included patients, 60% (111,046 of 186,231) were women, the mean age at surgery was 70 (± 10) years, and the median followup was 4.5 years (range, 0-14 years). A total of 101,094 patients had received a 28-mm, 57,853 a 32-mm, and 27,284 a 36-mm head with 32 mm used as the reference group. The revision of any component for any reason was the primary outcome and revision for dislocation was the secondary outcome. Very few patients are estimated to be lost to followup because emigration in the population of interest (older than 65-70 years) is rare. A Kaplan-Meier analysis was used to estimate THA survival for each group, whereas Cox regression models were fitted to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for THA revision comparing the 28- and 36-mm head diameters with the 32-mm head diameters adjusting for age, sex, year of surgery, type of cup and stem fixation, polyethylene type (crosslinked versus conventional), and surgical approach.

RESULTS

In the adjusted Cox regression model, there was no difference in the adjusted risk for revision for any reason between patients with 28-mm (HR, 1.06; 95% CI, 0.97-0.16) and 32-mm heads, whereas the risk of revision was higher for patients with 36-mm heads (HR, 1.14; 95% CI, 1.04-1.26) compared with patients with 32-mm heads. Patients with 28-mm heads had a higher risk of revision for dislocation (HR, 1.67; 95% CI, 1.38-1.98) compared with 32 mm, whereas there was no difference between patients with 36-mm (HR, 0.85; 95% CI, 0.70-1.02) and 32-mm heads.

CONCLUSIONS

After adjusting for relevant confounding variables, we found no benefits for 32-mm heads against 28 mm in terms of overall revision risk. However, when dislocation risk is considered, 32-mm heads would be a better option, because they had a lower risk of revision resulting from dislocation. There were no benefits with the use of 36-mm heads over 32 mm, because the transition from 32 to 36 mm was associated with a higher risk of revision for all reasons, which was not accompanied by a decrease in the risk of revision resulting from dislocation. The use of 32-mm heads appears to offer the best compromise between joint stability and other reasons for revision in MoP THA. Further studies with longer followup, especially of 36-mm heads, as well as better balance of confounders across head sizes and better control of patient-related risk factors for THA revision are needed.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Optimal position of lipped acetabular liners to improve stability in total hip arthroplasty-an intraoperative in vivo study

BACKGROUND

Lipped or elevated acetabular liners are frequently used in total hip arthroplasty to improve stability. However, the optimal position of the lip is not known. The purpose of this study was to determine the optimal position of lipped acetabular liners in total hip arthroplasty performed with a posterior approach.

METHODS

In 14 hips, lipped trial liners were placed intraoperatively in various positions around the posterior clock-face of the implanted acetabular shell component. For each liner position, stability of the hip was tested at maximal hip flexion with gradually increasing internal rotation until subluxation occurred, at which point the position of the hip was measured using smartphone accelerometer-based goniometers. Smartphone goniometers were first validated against a computer-assisted navigation system. Post-operative radiographs were analyzed for cup inclination angle, cup anteversion angle, and femoral offset.

RESULTS

Mean cup inclination angle in our series was 31° ± 6°. The most common liner position that imparted the greatest stability to posterior subluxation was posteriorly and inferiorly (4 o'clock position for left hip, or 8 o'clock position for right hip). The range for most stable liner position for different patients varied from postero-superior (11 o'clock/1 o'clock position) to directly inferior (6 o'clock position). Comparing a non-lipped liner to a lipped liner placed in the optimal position, the average difference in internal rotation gained before dislocation was 23°. There was no association between cup inclination or anteversion angle with liner position of greatest stability.

CONCLUSION

In hip replacements performed through a posterior approach and with mean cup inclination angle of 31° ± 6°, placing the lip of the elevated liner in the postero-inferior quadrant may impart more stability than in the postero-superior quadrant.

Can a Single-Use and Patient-Specific Instrumentation Be Reliably Used in Primary Total Knee Arthroplasty? A Multicenter Controlled Study

BACKGROUND

The aim of this controlled multicenter study is to evaluate the clinical and radiologic outcomes of primary total knee arthroplasty (TKA) using single-use fully disposable and patient-specific cutting guides (SU) and compare the results to those obtained with traditional patient-specific cutting guides (PSI) vs conventional instrumentation (CI).

METHODS

Seventy consecutive patients had their TKA performed using SU. They were compared to 140 historical patients requiring TKA that were randomized to have the procedure performed using PSI vs CI. The primary measure outcome was mechanical axis as measured on a standing long-leg radiograph using the hip-knee-ankle angle. Secondary outcome measures were Knee Society and Oxford knee scores, operative time, need for postoperative transfusion, and length of hospital stay.

RESULTS

The mean hip-knee-ankle value was 179.8° (standard deviation [SD] 3.1°), 179.2° (SD 2.9°), and 178.3° (SD 2.5°) in the CI, PSI and SU groups, respectively (P = .0082). Outliers were identified in 16 of 65 (24.6%), 15 of 67 (22.4%), and 14 of 70 (20.0%) knees in the CI, PSI, and SU group, respectively (P = .81). There was no significant difference in the clinical results (P = .29 and .19, respectively). Operative time, number of unit transfusion, and length of hospital stay were not significantly different between the 3 groups (P = .45, .31, and 0.98, respectively).

CONCLUSION

The use of an SU in TKA provided similar clinical and radiologic results to those obtained with traditional PSI and CI. The potential economic advantages of single-use instrumentation in primary TKA require further investigation.

Posterior or anterolateral approach in hip joint arthroplasty - Impact on frontal plane moment

BACKGROUND

Anterolateral surgical approach in hip joint arthroplasty necessitates division of the hip abductor muscle complex, which may compromise postoperative gait observed in the frontal plane. The aim of the study was to compare frontal plane moment after hip joint arthroplasty by anterolateral or posterior approach and to explore which compensatory strategies patients use to decrease frontal plane moment.

METHODS

Twenty-eight patients were randomized by sealed envelopes to hip resurfacing arthroplasty surgery by anterolateral (ad modum Watson) or posterior (ad modum Moore) approach, performed by two senior surgeons. Gait analyses were performed using 3D motion capture before surgery, 3, and 12 months after surgery. Peak ground reaction force was extracted for early and late stance and the corresponding frontal plane moment was defined. Measures of lateral trunk inclination, pelvic drop and hip abduction were obtained for the stance phase of the affected leg.

FINDINGS

An effect of surgical approach on frontal plane moment for the affected leg was found during early stance phase (p = 0.006) where average frontal plane moment in the anterolateral groups was 202.42 N mm/kg in less compared to the posterior group after one year. A similar effect from baseline to 12 months for trunk inclination (p = 0.03) and an overall negative correlation between frontal plane moment and trunk inclination was found (r = -0.66, p = 0.03).

INTERPRETATION

Frontal plane moment during early stance was less one year after hip joint arthroplasty through anterolateral compared to posterior approach. Patients' primary strategy to reduce frontal plane moment seems to be increased lateral trunk inclination.

Big Data and Health Research-The Governance Challenges in a Mixed Data Economy

Denmark is a society that has already moved towards Big Data and a Learning Health Care System. Data from routine healthcare has been registered centrally for years, there is a nationwide tissue bank, and there are numerous other available registries about education, employment, housing, pollution, etcetera. This has allowed Danish researchers to study the link between exposures, genetics and diseases in a large population. This use of public registries for scientific research has been relatively uncontroversial and has been supported by facilitative regulation that allows data to be used without the consent of data subjects. However, in the future much of the data will not be held by public authorities but by private companies. What are the implications of this shift for the governance of the research use of the data? This paper will argue that increased involvement of Research Ethics Committees and better training of researchers are necessary; and that some form of consent will have to be re-introduced. Four different consent models will be discussed: Opt-Out, Broad/Blanket consent, Dynamic consent, and Meta consent. It will be argued that a governance model including a possibility for citizens to make meta-choices strikes the best balance between individual and public interests.

Does hydroxyapatite coating of uncemented cups improve long-term survival? An analysis of 28,605 primary total hip arthroplasty procedures from the Nordic Arthroplasty Register Association (NARA)

OBJECTIVE

It is unclear whether hydroxyapatite (HA) coating of uncemented cups used in primary total hip arthroplasty (THA) improves bone ingrowth and reduces the risk of aseptic loosening. We therefore investigated survival of different uncemented cups that were available with or without HA coating.

METHOD

We investigated three different cup types used with or without HA coating registered in the Nordic Arthroplasty Register Association (NARA) database that were inserted due to osteoarthritis (n = 28,605). Cumulative survival rates and adjusted hazard ratios (HRs) for the risk of revision were calculated.

RESULTS

Unadjusted 13-year survival for cup revision due to aseptic loosening was 97.9% (CI: 96.5-99.4) for uncoated and 97.8% (CI: 96.3-99.4) for HA-coated cups. Adjusted HRs were 0.66 (CI 0.42-1.04) for the presence of HA coating during the first 10 years and 0.87 (CI 0.14-5.38) from year 10-13, compared with uncoated cups. When considering the endpoint cup revision for any reason, unadjusted 13-year survival was similar for uncoated (92.5% [CI: 90.1-94.9]) and HA-coated (94.7% [CI: 93.2-96.3]) cups. The risk of revision of any component due to infection was higher in THA with HA-coated cups than in THA with uncoated cups (adjusted HR 1.4 [CI 1.1-1.9]).

CONCLUSIONS

HA-coated cups have a similar risk of aseptic loosening as uncoated cups, thus the use of HA coating seems to not confer any added value in terms of implant stability. The risk of infection seemed higher in THA with use of HA-coated cups, an observation that must be investigated further.

Interventions for Improving Hip Resurfacing Outcomes in Women: A High-Volume, Retrospective Study

BACKGROUND

Women seeking surgical intervention for their hip disorders will often find total hip arthroplasty (THA) presented as their only option. THA, when compared with hip resurfacing arthroplasty, removes substantially more bone-stock, limits range-of-motion, exhibits increased dislocation risk, and presents greater overall 10-year mortality rate. Despite these risks, most surgeons continue to select against women for hip resurfacing because registries notoriously report inferior survivorship when compared with men and THA.

METHODS

We investigated the reasons for why resurfacing arthroplasty devices survive poorly in women to develop interventions which might improve hip resurfacing outcomes in women. Using these findings, we developed a series of surgical interventions to treat the underlying issues. Herein, we compare 2 study groups: women who received hip resurfacings before (group 1) and after (group 2) these interventions.

RESULTS

Eight-year implant survivorship substantially improved from 89.6% for group 1 to 97.7% for group 2. Adverse wear-related failure, femoral component loosening, and acetabular component loosening were all significantly reduced in group 2, which we attribute to the implementation of our relative acetabular inclination limit guidelines, use of uncemented femoral fixation, and selection of the Tri-Spike acetabular component for supplemental fixation, respectively. Kaplan-Meier implant survivorship curves, grouped into 2-year time intervals, show that the disparity in failure rates between men and women is diminishing.

CONCLUSION

When experienced surgeons use refined and proper surgical technique, women show promise as excellent candidates for hip resurfacing as an alternative treatment for their debilitating hip conditions.

Hospital volume and the risk of revision in Oxford unicompartmental knee arthroplasty in the Nordic countries -an observational study of 14,496 cases

Background

High procedure volume and dedication to unicompartmental knee arthroplasty (UKA) has been suggested to improve revision rates. This study aimed to quantify the annual hospital volume effect on revision risk in Oxfordu nicompartmental knee arthroplasty in the Nordic countries.

Methods

14,496 cases of cemented medial Oxford III UKA were identified in 126 hospitals in the four countries included in the Nordic Arthroplasty Register Association (NARA) database from 2000 to 2012. Hospitals were divided by quartiles into 4 annual procedure volume groups (≤11, 12-23, 24-43 and ≥44). The outcome was revision risk after 2 and 10 years calculated using Kaplan Meier method. Multivariate Cox regression analysis was used to assess the Hazard Ratio (HR) of any revision due to specific reasons with 95% confidence intervals (CI).

Results

The implant survival was 80% at 10 years in the volume group ≤11 procedures per year compared to 83% in other volume groups. The HR adjusted for age category, sex, year of surgery and nation was 0.87 (95% CI: 0.76-0.99, p = 0.036) for the group 12-23 procedures per year, 0.78 (95% CI: 0.68-0.91, p = 0.002) for the group 24-43 procedures per year and 0.82 (95% CI: 0.70-0.94, p = 0.006) for the group ≥44 procedures per year compared to the low volume group. Log-rank test was p = 0.003. The risk of revision for unexplained pain was 40-50% higher in the low compared with other volume groups.

Conclusion

Low volume hospitals performing ≤11 Oxford III UKAs per year were associated with an increased risk of revision compared to higher volume hospitals, and unexplained pain as revision cause was more common in low volume hospitals.

Metal-on-metal hip resurfacing in patients younger than 50 years: a retrospective analysis : 1285 cases, 12-year survivorship

BACKGROUND

The Nordic registry reports patients under 50 years old with total hip replacements realize only 83% 10-year implant survivorship. These results do not meet the 95% 10-year survivorship guideline posed by the UK's National Institute for Health and Care Excellence (NICE) in 2014.

METHODS

The purpose of this study is threefold: First, we evaluate if metal-on-metal hip resurfacing arthroplasty meets these high standards in younger patients. Next, we compare outcomes between age groups to determine if younger patients are at higher risk for revision or complication. Lastly, we assess how outcomes between sexes changed over time. From January 2001 to August 2013, a single surgeon performed 1285 metal-on-metal hip resurfacings in patients younger than 50 years old. We compared these to an older cohort matched by sex and BMI.

RESULTS

Kaplan-Meier implant survivorship was 96.5% at 10 years and 96.3% at 12 years; this did not differ from implant survivorship for older patients. Implant survivorship at 12 years was 98 and 93% for younger men and women, respectively; survivorship for women improved from 93 to 97% by using exclusively Biomet implants. There were four (0.3%) adverse wear-related failures, with no instances of wear or problematic ion levels since 2009. Activity scores improved from 5.4 ± 2.3 preoperatively to 7.6 ± 1.9 postoperatively (p < 0.0001), with 43% of patients reporting a UCLA activity score of 9 or 10.

CONCLUSIONS

Hip resurfacing exceeds the stricter 2014 NICE survivorship criteria independently in men and women even when performed on patients under 50 years old.

Reverse hybrid total hip arthroplasty

Background and purpose - The use of a cemented cup together with an uncemented stem in total hip arthroplasty (THA) has become popular in Norway and Sweden during the last decade. The results of this prosthetic concept, reverse hybrid THA, have been sparsely described. The Nordic Arthroplasty Register Association (NARA) has already published 2 papers describing results of reverse hybrid THAs in different age groups. Based on data collected over 2 additional years, we wanted to perform in depth analyses of not only the reverse hybrid concept but also of the different cup/stem combinations used. Patients and methods - From the NARA, we extracted data on reverse hybrid THAs from January 1, 2000 until December 31, 2013. 38,415 such hips were studied and compared with cemented THAs. The Kaplan-Meier method and Cox regression analyses were used to estimate the prosthesis survival and the relative risk of revision. The main endpoint was revision for any reason. We also performed specific analyses regarding the different reasons for revision and analyses regarding the cup/stem combinations used in more than 500 cases. Results - We found a higher rate of revision for reverse hybrids than for cemented THAs, with an adjusted relative risk of revision (RR) of 1.4 (95% CI: 1.3-1.5). At 10 years, the survival rate was 94% (CI: 94-95) for cemented THAs and 92% (95% CI: 92-93) for reverse hybrids. The results for the reverse hybrid THAs were inferior to those for cemented THAs in patients aged 55 years or more (RR =1.1, CI: 1.0-1.3; p < 0.05). We found a higher rate of early revision due to periprosthetic femoral fracture for reverse hybrids than for cemented THAs in patients aged 55 years or more (RR =3.1, CI: 2.2-4.5; p < 0.001). Interpretation - Reverse hybrid THAs had a slightly higher rate of revision than cemented THAs in patients aged 55 or more. The difference in survival was mainly caused by a higher incidence of early revision due to periprosthetic femoral fracture in the reversed hybrid THAs.

Lower limb arthroplasty: can we produce a tool to predict outcome and failure, and is it cost-effective? An epidemiological study

Background

Although hip and knee arthroplasties are considered to be common elective cost-effective operations, up to one-quarter of patients are not satisfied with the operation. A number of risk factors for implant failure are known, but little is known about the predictors of patient-reported outcomes.

Objectives

(1) Describe current and future needs for lower limb arthroplasties in the UK; (2) describe important risk factors for poor surgery outcomes and combine them to produce predictive tools (for hip and knee separately) for poor outcomes; (3) produce a Markov model to enable a detailed health economic analysis of hip/knee arthroplasty, and for implementing the predictive tool; and (4) test the practicality of the prediction tools in a pragmatic prospective cohort of lower limb arthroplasty.

Design

The programme was arranged into four work packages. The first three work packages used the data from large existing data sets such as Clinical Practice Research Datalink, Hospital Episode Statistics and the National Joint Registry. Work package 4 established a pragmatic cohort of lower limb arthroplasty to test the practicality of the predictive tools developed within the programme.

Results

The estimated number of total knee replacements (TKRs) and total hip replacements (THRs) performed in the UK in 2015 was 85,019 and 72,418, respectively. Between 1991 and 2006, the estimated age-standardised rates (per 100,000 person-years) for a THR increased from 60.3 to 144.6 for women and from 35.8 to 88.6 for men. The rates for TKR increased from 42.5 to 138.7 for women and from 28.7 to 99.4 for men. The strongest predictors for poor outcomes were preoperative pain/function scores, deprivation, age, mental health score and radiographic variable pattern of joint space narrowing. We found a weak association between body mass index (BMI) and outcomes; however, increased BMI did increase the risk of revision surgery (a 5-kg/m2rise in BMI increased THR revision risk by 10.4% and TKR revision risk by 7.7%). We also confirmed that osteoarthritis (OA) severity and migration pattern of the hip predicted patient-reported outcome measures. The hip predictive tool that we developed performed well, with a correctedR2of 23.1% and had good calibration, with only slight overestimation of Oxford Hip Score in the lowest decile of outcome. The knee tool developed performed less well, with a correctedR2of 20.2%; however, it had good calibration. The analysis was restricted by the relatively limited number of variables available in the extant data sets, something that could be addressed in future studies. We found that the use of bisphosphonates reduced the risk of revision knee and hip surgery by 46%. Hormone replacement therapy reduced the risk by 38%, if used for at least 6 months postoperatively. We found that an increased risk of postoperative fracture was prevented by bisphosphonate use. This result, being observational in nature, will require confirmation in a randomised controlled trial. The Markov model distinguished between outcome categories following primary and revision procedures. The resulting outcome prediction tool for THR and TKR reduced the number and proportion of unsatisfactory outcomes after the operation, saving NHS resources in the process. The highest savings per quality-adjusted life-year (QALY) forgone were reported from the oldest patient subgroups (men and women aged ≥ 80 years), with a reported incremental cost-effectiveness ratio of around £1200 saved per QALY forgone for THRs. In the prospective cohort of arthroplasty, the performance of the knee model was modest (R2 = 0.14) and that of the hip model poor (R2 = 0.04). However, the addition of the radiographic OA variable improved the performance of the hip model (R2 = 0.125 vs. 0.110) and high-sensitivity C-reactive protein improved the performance of the knee model (R2 = 0.230 vs. 0.216). These data will ideally need replication in an external cohort of a similar design. The data are not necessarily applicable to other health systems or countries.

Conclusion

The number of total hip and knee replacements will increase in the next decade. High BMI, although clinically insignificant, is associated with an increased risk of revision surgery and postoperative complications. Preoperative pain/function, the pattern of joint space narrowing, deprivation index and level of education were found to be the strongest predictors for THR. Bisphosphonates and hormone therapy proved to be beneficial for patients undergoing lower limb replacement. The addition of new predictors collected from the prospective cohort of arthroplasty slightly improved the performance of the predictive tools, suggesting that the potential improvements in both tools can be achieved using the plethora of extra variables from the validation cohort. Although currently it would not be cost-effective to implement the predictive tools in a health-care setting, we feel that the addition of extensive risk factors will improve the performances of the predictive tools as well as the Markov model, and will prove to be beneficial in terms of cost-effectiveness. Future analyses are under way and awaiting more promising provisional results.

Future work

Further research should focus on defining and predicting the most important outcome to the patient.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

Clinical epidemiology in the era of big data: new opportunities, familiar challenges

Routinely recorded health data have evolved from mere by-products of health care delivery or billing into a powerful research tool for studying and improving patient care through clinical epidemiologic research. Big data in the context of epidemiologic research means large interlinkable data sets within a single country or networks of multinational databases. Several Nordic, European, and other multinational collaborations are now well established. Advantages of big data for clinical epidemiology include improved precision of estimates, which is especially important for reassuring (“null”) findings; ability to conduct meaningful analyses in subgroup of patients; and rapid detection of safety signals. Big data will also provide new possibilities for research by enabling access to linked information from biobanks, electronic medical records, patient-reported outcome measures, automatic and semiautomatic electronic monitoring devices, and social media. The sheer amount of data, however, does not eliminate and may even amplify systematic error. Therefore, methodologies addressing systematic error, clinical knowledge, and underlying hypotheses are more important than ever to ensure that the signal is discernable behind the noise.

Patient-reported health outcomes after total hip and knee surgery in a Dutch University Hospital Setting: results of twenty years clinical registry

Background

Patient-Reported Outcome (PRO) measurement is a method for measuring perceptions of patients on their health and quality of life. The aim of this paper is to present the results of PRO measurements in total hip and knee replacement as routinely collected during 20 years of surgery in a university hospital setting.

Methods

Data of consecutive patients between 1993 and 2014 were collected. Health outcomes were measured pre-surgery and at 3, 6, and 12 months post-surgery. Outcomes for hip replacement were measured with the Harris Hip Score (HHS) and Oxford Hip Score (OHS). Outcomes for knee replacement were measured with the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the Knee Society Score (KSS). A Visual Analog Scale (VAS) for pain was used. Absolute and relative Minimal Clinically Important Differences (MCID) were estimated. Generalized estimating equation analysis was used for estimating mean outcomes. Trends over time were analyzed.

Results

The database contained 2,089 patients with hip replacement, and 704 patients with knee replacement. Mean HHS and OHS scores in primary hip replacement at 12 months post-surgery were 86.7 (SD: 14.5) and 41.1 (SD: 7.5) respectively. Improvements on the HHS based on absolute MCID was lower for revisions compared to primary hip replacements, with 72.4% and 87.0% respectively. Mean WOMAC and KSS scores in knee replacement at 12 months post-surgery were 21.5 (SD: 18.2) and 67.0 (SD: 26.4) respectively. Improvements based on absolute MCID were lowest for the KSS (62.6%) and highest for VAS pain (85.6%). Trend analysis showed a difference in 1 out of 24 comparisons in hip replacement and in 2 out of 9 comparisons in knee replacement.

Conclusions

The functional status of a large cohort of patients significantly improved after hip and knee replacement based on routine data collection. Our study shows the feasibility of the routine collection of PRO data in patients with total hip and knee replacement. The use of PRO data provides opportunities for continuous quality improvement.

Is it feasible to merge data from national shoulder registries? A new collaboration within the Nordic Arthroplasty Register Association

BACKGROUND

The Nordic Arthroplasty Register Association was initiated in 2007, and several papers about hip and knee arthroplasty have been published. Inspired by this, we aimed to examine the feasibility of merging data from the Nordic national shoulder arthroplasty registries by defining a common minimal data set.

METHODS

A group of surgeons met in 2014 to discuss the feasibility of merging data from the national shoulder registries in Denmark, Norway, and Sweden. Differences in organization, definitions, variables, and outcome measures were discussed. A common minimal data set was defined as a set of variables containing only data that all registries could deliver and where consensus according to definition of the variables could be made.

RESULTS

We agreed on a data set containing patient-related data (age, gender, and diagnosis), operative data (date, arthroplasty type and brand), and data in case of revision (date, reason for revision, and new arthroplasty brand). From 2004 to 2013, there were 19,857 primary arthroplasties reported. The most common indications were osteoarthritis (35%) and acute fracture (34%). The number of arthroplasties and especially the number of arthroplasties for osteoarthritis have increased in the study period. The most common arthroplasty type was total shoulder arthroplasty (34%) for osteoarthritis and stemmed hemiarthroplasty (90%) for acute fractures.

CONCLUSION

We were able to merge data from the Nordic national registries into 1 common data set; however, the set of details was reduced. We found considerable differences between the 3 countries regarding incidence of shoulder arthroplasty, age, diagnoses, and choice of arthroplasty type and brand.

The Danish Hip Arthroplasty Register

Aim of database

The aim of the Danish Hip Arthroplasty Register (DHR) is to continuously monitor and improve the quality of treatment of primary and revision total hip arthroplasty (THA) in Denmark.

Study population

The DHR is a Danish nationwide arthroplasty register established in January 1995. All Danish orthopedic departments – both public and private – report to the register, and registration is compulsory.

Main variables

The main variables in the register include civil registration number, indication for primary and revision surgery, operation date and side, and postoperative complications. Completeness of primary and revision surgery is evaluated annually and validation of a number of variables has been carried out.

Descriptive data

A total of 139,525 primary THAs and 22,118 revisions have been registered in the DHR between January 1, 1995 and December 31, 2014. Since 1995, completeness of procedure registration has been high, being 97.8% and 92.0% in 2014 for primary THAs and revisions, respectively. Several risk factors, such as comorbidity, age, specific primary diagnosis and fixation types for failure of primary THAs, and postoperative complications, have been identified through the DHR. Approximately 9,000 primary THAs and 1,500 revisions are reported to the register annually.

Conclusion

The DHR is important for monitoring and improvement of treatment with THA and is a valuable tool for research in THA surgery due to the high quality of prospective collected data with long-term follow-up and high completeness. The register can be used for population-based epidemiology studies of THA surgery and can be linked to a range of other national databases.

Big Data, Big Research: Implementing Population Health-Based Research Models and Integrating Care to Reduce Cost and Improve Outcomes

Recent trends in clinical research have moved attention toward reporting clinical outcomes and resource consumption associated with various care processes. This change is the result of technological advancement and a national effort to critically assess health care delivery. As orthopedic surgeons traverse an unchartered health care environment, a more complete understanding of how clinical research is conducted using large data sets is necessary. The purpose of this article is to review various advantages and disadvantages of large data sets available for orthopaedic use, examine their ideal use, and report how they are being implemented nationwide.

Prevalence of knee arthroplasty in the state of São Paulo between 2003 and 2010

CONTEXT AND OBJECTIVE:

The volume of knee arthroplasty procedures has increased over the last decade. The aim of this study was to estimate the frequency of these procedures performed within the public healthcare system of the state of São Paulo between 2003 and 2010.

DESIGN AND SETTING:

Cross-sectional study conducted in the state of São Paulo by researchers at Hospital do Servidor Público do Estado de São Paulo.

METHODS:

A sample of 10,952 patients (7,891 females and 3,061 males) who underwent primary total knee arthroplasty (TKA) and revision of total knee arthroplasty (RTKA) in the state of São Paulo between 2003 and 2010 was evaluated. The patients were cataloged using the public healthcare service's TABNET software. All of the patients presented primary osteoarthritis of the knee. The variables of gender, number of primary TKA procedures and number of RTKA procedures were evaluated.

RESULTS:

A total of 10,952 TKA procedures were performed (annual average of 1369), of which 9,271 (85%) were TKA and 1,681 (15%), RTKA. Of the TKA procedures, 72% were carried out on females (P < 0.0001), while 70% of the RTKA procedures were on females (P < 0.0001). The average ratio of TKA to RTKA was 5.5:1 (P < 0.0001); the ratios in 2003 and 2010 were 9.0:1 and 4.4:1 (P < 0.0001), respectively.

CONCLUSION:

The number and frequency of TKA and RTKA procedures increased in the state of São Paulo between 2003 and 2010. This increase was relatively greater in RTKA than in TKA and was predominantly in female patients.

Assessing the comparability of hip arthroplasty registries in order to improve the recording and monitoring of outcome

Aims

We aimed to assess the comparability of data in joint replacement registries and identify ways of improving the comparisons between registries and the overall monitoring of joint replacement surgery.

Materials and Methods

We conducted a review of registries that are full members of the International Society of Arthroplasty Registries with publicly available annual reports in English. Of the six registries which were included, we compared the reporting of: mean age, definitions for revision and re-operation, reasons for revision, the approach to analysing revisions, and patient-reported outcome measures (PROMs) for primary and revision total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA).

Results

Outcomes were infrequently reported for HRA compared with THA and all hip arthroplasties. Revisions were consistently defined, though re-operation was defined by one registry. Implant survival was most commonly reported as the cumulative incidence of revision using Kaplan-Meier survival analysis. Three registries reported patient reported outcome measures.

Conclusion

More consistency in the reporting of outcomes for specific types of procedures is needed to improve the interpretation of joint registry data and accurately monitor safety trends. As collecting additional details of surgical and patient-reported outcomes becomes increasingly important, the experience of established registries will be valuable in establishing consistency among registries while maintaining the quality of data. Take home message: As the volume of joint replacements performed each year continues to increase, greater consistency in the reporting of surgical and patient-reported outcomes among joint replacement registries would improve the interpretation and comparability of these data to monitor outcomes accurately. Cite this article: Bone Joint J 2016;98-B:442–51.

Association between hospital procedure volume and risk of revision after total hip arthroplasty: a population-based study within the Nordic Arthroplasty Register Association database

OBJECTIVE

Outcome after total hip arthroplasty (THA) depends on several factors related to the patient, the surgeon and the implant. It has been suggested that the annual number of procedures per hospital affects the prognosis. We aimed to examine if hospital procedure volume was associated with the risk of revision after primary THA in the Nordic countries from 1995 to 2011.

DESIGN

The Nordic Arthroplasty Register Association database provided information about primary THA, revision and annual hospital volume. Hospitals were divided into five volume groups (1-50, 51-100, 101-200, 201-300, >300). The outcome of interest was risk of revision 1, 2, 5, 10 and 15 years after primary THA. Multivariable regression was used to assess the relative risk (RR) of revision.

RESULTS

417,687 THAs were included. For the 263,176 cemented THAs no differences were seen 1 year after primary procedure. At 2, 5, 10 and 15 years the four largest hospital volume groups had a reduced risk of revision compared to group 1-50. After 10 years RR was for volume group 51-100 0.79 (CI 0.65-0.95), group 101-200 0.76 (CI 0.61-0.95), group 201-300 0.74 (CI 0.57-0.96) and group >300 0.57 (CI 0.46-0.71). For the uncemented THAs an association between hospital volume and risk of revision were only present for hospitals producing 201-300 THAs per year, beginning at years 2 through 5 and in all subsequent time intervals to 15 years.

CONCLUSION

Hospital procedure volume was associated with a long term risk of revision after primary cemented THA. Hospitals operating 50 procedures or less per year had an increased risk of revision after 2, 5, 10 and 15 years follow up.

Early Mechanical Failures of the Synthes Variable Angle Locking Distal Femur Plate

OBJECTIVES

To document the high failure rate of a specific implant: the Synthes Variable Angle (VA) Locking Distal Femur Plate.

DESIGN

Retrospective.

SETTING

Urban University Level I Trauma Center.

PATIENT/PARTICIPANTS

All distal femur fractures (OTA/AO 33-A, B, C) treated from March 2011 through August 2013 were reviewed from our institutional orthopaedic trauma registry. Inclusion criteria were fractures treated with a precontoured distal femoral locking plate and age between 18 and 84. Exclusion criteria were fractures treated with intramedullary nails, arthroplasty, non-precontoured plates, dual plating, or screw fixation alone. The population was divided into 3 groups: less invasive stabilization system (LISS) group (n = 21), treated with LISS plates (Synthes, Paoli, PA); locking condylar plates (LCPs) group (n = 10), treated with LCPs (Synthes, Paoli, PA); and VA group (n = 36), treated with VA distal femoral LCPs (Synthes, Paoli, PA). Average age was 54.6 ± 17.5 years.

INTERVENTION

Open reduction internal fixation with one of the above implants was performed.

MAIN OUTCOME MEASURES

The patients were followed radiographically for early mechanical implant failure defined as loosening of locking screws, loss of fixation, plate bending, or implant failure.

RESULTS

There were no statistically significant differences between groups for age, gender, open fracture, mechanism of injury, or medial comminution. There were 3 failures (14.3%) in group LISS, no failures (0%) in group LCP, and 8 failures (22.2%) in group VA. All 3 failures in group LISS were in A-type fractures (2 periprosthetic) and all failures in group VA were in C-type fractures. When all fractures for all 3 groups were compared for failure rate, there was no statistically significant difference (P = 0.23). However, when only 33-C fractures were compared, there was significantly greater failure rate in the VA group (P = 0.03). The mean time to failure in group VA was 147 days (range 24-401 days) and was significantly earlier (P = 0.034) when compared with group LISS (mean 356 days; range 251-433 days).

CONCLUSIONS

Early mechanical failure with the VA distal femoral locking plate is higher than traditional locking plates (LCP and LISS) for OTA/AO 33-C fractures. We caution practicing surgeons against the use of this plate for metaphyseal fragmented distal femur fractures.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Bigger Data, Bigger Problems

Clinical studies frequently lack the ability to reliably answer their research questions because of inadequate sample sizes. Underpowered studies are subject to multiple sources of bias, may not represent the larger population, and are regularly unable to detect differences between treatment groups. Most importantly, an underpowered study can lead to incorrect conclusions. Big data can be used to address many of these concerns, enabling researchers to answer questions with increased certainty and less likelihood of bias. Big datasets, such as The National Hip Fracture Database in the United Kingdom and the Swedish Hip Arthroplasty Registry, collect valuable clinical information that can be used by researchers to guide patient care and inform policy makers, chief executives, commissioners, and clinical staff. The range of research questions that can be examined is directly related to the quality and complexity of the data, which is positively associated with the cost of the data. However, technological advancements have unlocked new possibilities for efficient data capture and widespread opportunities to merge massive datasets, particularly in the setting of national registries and administrative data.

Is a Revision a Revision? An Analysis of National Arthroplasty Registries' Definitions of Revision

BACKGROUND

The reported survival of implants depends on the definition used for the endpoint, usually revision. When screening through registry reports from different countries, it appears that revision is defined quite differently.

QUESTIONS/PURPOSES

The purposes of this study were to compare the definitions of revision among registry reports and to apply common clinical scenarios to these definitions.

METHODS

We downloaded or requested reports of all available national joint registries. Of the 23 registries we identified, 13 had published reports that were available in English and were beyond the pilot phase. We searched these registries' reports for the definitions of the endpoint, mostly revision. We then applied the following scenarios to the definition of revision and analyzed if those scenarios were regarded as a revision: (A) wound revision without any addition or removal of implant components (such as hematoma evacuation); (B) exchange of head and/or liner (like for infection); (C) isolated secondary patella resurfacing; and (D) secondary patella resurfacing with a routine liner exchange.

RESULTS

All registries looked separately at the characteristic of primary implantation without a revision and 11 of 13 registers reported on the characteristics of revisions. Regarding the definition of revision, there were considerable differences across the reports. In 11 of 13 reports, the primary outcome was revision of the implant. In one registry the primary endpoint was "reintervention/revision" while another registry reported separately on "failure" and "reoperations". In three registries, the definition of the outcome was not provided, however in one report a results list gave an indication for the definition of the outcome. Wound revision without any addition or removal of implant components (scenario A) was considered a revision in three of nine reports that provided a clear definition on this question, whereas two others did not provide enough information to allow this determination. Exchange of the head and/or liner (like for infection; scenario B) was considered a revision in 11 of 11; isolated secondary patella resurfacing (scenario C) in six of eight; and secondary patella resurfacing with routine liner exchange (scenario D) was considered a revision in nine of nine reports.

CONCLUSIONS

Revision, which is the most common main endpoint used by arthroplasty registries, is not universally defined. This implies that some reoperations that are considered a revision in one registry are not considered a revision in another registry. Therefore, comparisons of implant performance using data from different registries have to be performed with caution. We suggest that registries work to harmonize their definitions of revision to help facilitate comparisons of results across the world's arthroplasty registries.

Hydroxyapatite coating does not improve uncemented stem survival after total hip arthroplasty!

BACKGROUND AND PURPOSE

It is still being debated whether HA coating of uncemented stems used in total hip arthroplasty (THA) improves implant survival. We therefore investigated different uncemented stem brands, with and without HA coating, regarding early and long-term survival.

PATIENTS AND METHODS

We identified 152,410 THA procedures using uncemented stems that were performed between 1995 and 2011 and registered in the Nordic Arthroplasty Register Association (NARA) database. We excluded 19,446 procedures that used stem brands less than 500 times in each country, procedures performed due to diagnoses other than osteoarthritis or pediatric hip disease, and procedures with missing information on the type of coating. 22 stem brands remained (which were used in 116,069 procedures) for analysis of revision of any component. 79,192 procedures from Denmark, Norway, and Sweden were analyzed for the endpoint stem revision. Unadjusted survival rates were calculated according to Kaplan-Meier, and Cox proportional hazards models were fitted in order to calculate hazard ratios (HRs) for the risk of revision with 95% confidence intervals (CIs).

RESULTS

Unadjusted 10-year survival with the endpoint revision of any component for any reason was 92.1% (CI: 91.8-92.4). Unadjusted 10-year survival with the endpoint stem revision due to aseptic loosening varied between the stem brands investigated and ranged from 96.7% (CI: 94.4-99.0) to 99.9% (CI: 99.6-100). Of the stem brands with the best survival, stems with and without HA coating were found. The presence of HA coating was not associated with statistically significant effects on the adjusted risk of stem revision due to aseptic loosening, with an HR of 0.8 (CI: 0.5-1.3; p = 0.4). The adjusted risk of revision due to infection was similar in the groups of THAs using HA-coated and non-HA-coated stems, with an HR of 0.9 (CI: 0.8-1.1; p = 0.6) for the presence of HA coating. The commonly used Bimetric stem (n = 25,329) was available both with and without HA coating, and the adjusted risk of stem revision due to aseptic loosening was similar for the 2 variants, with an HR of 0.9 (CI: 0.5-1.4; p = 0.5) for the HA-coated Bimetric stem.

INTERPRETATION

Uncemented HA-coated stems had similar results to those of uncemented stems with porous coating or rough sand-blasted stems. The use of HA coating on stems available both with and without this surface treatment had no clinically relevant effect on their outcome, and we thus question whether HA coating adds any value to well-functioning stem designs.

Registries in orthopaedics

The first nationwide orthopaedic registry was created in Sweden in 1975 to collect data on total knee arthroplasty (TKA). Since then, several countries have established registries, with varying degrees of success. Managing a registry requires time and money. Factors that contribute to successful registry management include the use of a single identifier for each patient to ensure full traceability of all procedures related to a given implant; a long-term funding source; a contemporary, rapid, Internet-based data collection method; and the collection of exhaustive data, at least for innovative implants. The effects of registries on practice patterns should be evaluated. The high cost of registries raises issues of independence and content ownership. Scandinavian countries have been maintaining orthopaedic registries for nearly four decades (since 1975). The first English-language orthopaedic registry was not created until 1998 (in New Zealand), and both the US and many European countries are still struggling to establish orthopaedic registries. To date, there are 11 registered nationwide registries on total knee and total hip replacement. The data they contain are often consistent, although contradictions occur in some cases due to major variations in cultural and market factors. The future of registries will depend on the willingness of health authorities and healthcare professionals to support the creation and maintenance of these tools. Surgeons feel that registries should serve merely to compare implants. Health authorities, in contrast, have a strong interest in practice patterns and healthcare institution performances. Striking a balance between these objectives should allow advances in registry development in the near future.

Current state of anterior cruciate ligament registers

PURPOSE

The purpose of this work was to report the main characteristics and results of all active anterior cruciate ligament (ACL) reconstruction registers along with the differences between them.

METHODS

We systematically searched on Google and Medline via PubMed to identify ACL registers. National or regional registers were included if they were active and took into account ACL reconstructions. The main results and characteristics, namely the number of inclusions, exhaustivity, data collection methods and results dissemination methods were determined. The collected information was then submitted to each register for validation.

RESULTS

Four registers (3 national, 1 regional) were identified that routinely included every ACL reconstruction procedure. Register data were collected either through dedicated websites or on paper forms. All the registers used the same two outcome measures, namely the revision rate and a subjective patient score (KOOS score). Register results were made available through scientific publications or annual reports. The main differences between registers were in the graft choice and presence of associated meniscus and cartilage injuries.

CONCLUSIONS

Although there are only a few ACL reconstruction-specific registers, their scientific contribution is undeniable thanks to the quality of the collected data and the organization and collaboration between registers. Their impact on health care and science should grow in the future.

Analgesic techniques in hip and knee arthroplasty: from the daily practice to evidence-based medicine

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are major orthopedic surgery models, addressing mainly ageing populations with multiple comorbidities and treatments, ASA II–IV, which may complicate the perioperative period. Therefore effective management of postoperative pain should allow rapid mobilization of the patient with shortening of hospitalization and social reintegration. In our review we propose an evaluation of the main analgesics models used today in the postoperative period. Their comparative analysis shows the benefits and side effects of each of these methods and guides us to how to use evidence-based medicine in our daily practice.

Periprosthetic femoral fracture within two years after total hip replacement: analysis of 437,629 operations in the nordic arthroplasty register association database

BACKGROUND

We used the Nordic Arthroplasty Register Association database to evaluate whether age, sex, preoperative diagnosis, fixation, and implant design influence the risk of revision arthroplasty due to periprosthetic fracture within two years from operation of a primary total hip replacement.

METHODS

Included in the study were 325,730 cemented femoral stems and 111,899 uncemented femoral stems inserted from 1995 to 2009. Seven frequently used stems (two cemented stems [Exeter and Lubinus SP II] and five uncemented stems [Bi-Metric, Corail, CLS Spotorno, ABG I, and ABG II]) were specifically studied.

RESULTS

The incidence of revision at two years was low: 0.47% for uncemented stems and 0.07% for cemented stems. Uncemented stems were much more likely to have this complication (relative risk, 8.72 [95% confidence interval, 7.37 to 10.32]; p < 0.0005). Age had no consistent influence on the risk for revision of cemented stems, but revision in the uncemented group increased with increasing age. A cemented stem was associated with a higher risk in male patients compared with female patients (hazard ratio, 1.95 [95% confidence interval, 1.51 to 2.53]; p < 0.0005), whereas an uncemented stem was associated with a reduced risk in male patients compared with female patients (hazard ratio, 0.74 [95% confidence interval, 0.62 to 0.89]; p = 0.001). The risk for revision due to early periprosthetic fracture increased during the 2003 to 2009 period compared with the 1995 to 2002 period both before and after adjustment for demographic factors and fixation (relative risk, 1.44 [95% confidence interval, 1.18 to 1.69]; p < 0.0005). The hazard ratio for the Exeter stem was about five times higher than that for the Lubinus SP II stem (hazard ratio, 5.03 [95% confidence interval, 3.29 to 7.70]; p < 0.0005). Of the five uncemented stems, the ABG II stem showed an increased hazard ratio of 1.63 (95% confidence interval, 1.16 to 2.28) (p = 0.005), whereas the Corail stem showed a decreased hazard ratio of 0.47 (95% confidence interval, 0.34 to 0.65) (p < 0.0005) compared with the reference Bi-Metric design.

CONCLUSIONS

The shape and surface finish of the femoral stem and its fixation could be related to the increased risk of some prosthetic designs. Even if the incidence of early periprosthetic fracture in general is low and other reasons for revision must be considered, specific attention should be given to the choice of fixation and stem design in risk groups.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The use of a lipped acetabular liner decreases the rate of revision for instability after total hip replacement: a study using data from the New Zealand Joint Registry

We compared the rate of revision for instability after total hip replacement (THR) when lipped and non-lipped acetabular liners were used. We hypothesised that the use of a lipped liner in a modular uncemented acetabular component reduces the risk of revision for instability after primary THR. Using data from the New Zealand Joint Registry, we found that the use of a lipped liner was associated with a significantly decreased rate of revision for instability and for all other indications. Adjusting for the size of the femoral head, the surgical approach and the age and gender of the patient, this difference remained strongly significant (p < 0.001). We conclude that evidence from the New Zealand registry suggests that the use of lipped liners with modular uncemented acetabular components is associated with a decreased rate of revision for instability after primary THR.

Joint registries as continuous surveillance systems: the experience of the Catalan Arthroplasty Register (RACat)

The aim was to present results on prosthesis performance in Catalonia for the period 2005-2010. All publicly funded hospitals submit in an electronic format data on hip and knee arthroplasties: patients' insurance identification number, hospital, joint (hip/knee), type of arthroplasty (primary/revision), side (right/left), date of surgery and prosthesis (manufacturer name and catalogue number). A standard survival analysis based on Kaplan-Meier estimation was carried out. Fifty-two hospitals have sent information to the RACat which has data on 36,951 knee and 26,477 hip arthroplasties. Cumulative prostheses revision risks at 3 years were 3.3% (95% CI: 3.1-3.6) for knee, 2.9% (95% CI: 2.5-3.3) for total hip and 2.5% (95% CI: 2.0-3.1) for partial hip. When compared to other registries a higher risk of revision was observed.

Acetabular liner with focal constraint to prevent dislocation after THA

BACKGROUND

Dislocation continues to commonly cause failure after primary and revision total hip arthroplasty (THA). Fully constrained liners intended to prevent dislocation are nonetheless associated with a substantial incidence of failure by redislocation, mechanical failure, aseptic loosening, or a combination. Constrained liners with cutouts of the elevated rims can theoretically increase range of movement and therefore decrease the risk dislocation, but it is unclear if they do so in practice and whether they are associated with early wear or loosening.

QUESTIONS/PURPOSES

We therefore determined (1) occurrence or recurrence of dislocation and (2) rate of complications associated with constrained implants with cutouts; and (3) assessed for early cup loosening.

METHODS

We retrospectively reviewed the records of 81 patients at high risk for dislocation who had 82 constrained liners inserted for primary (n = 10) or revision (n = 72) THA between 2008 and 2010. From the records we extracted demographic and implant data and instances of recurrent dislocation, implant failure, osteolysis, loosening, or construct failure. The minimum followup was 24 months (mean, 34 months; range, 24-49 months).

RESULTS

Three liners failed as a result of further dislocation (3%). Three deep infections occurred. One patient had progressive loosening at the shell-bone interface.

CONCLUSIONS

Our observations suggest this liner is associated with a relatively low risk of dislocation in patients at high risk for dislocation and those with recurrent dislocation.

A population-based survival analysis describing the association of body mass index on time to revision for total hip and knee replacements: results from the UK general practice research database

OBJECTIVES

Against a backdrop of rising levels of obesity, we describe and estimate associations of body mass index (BMI), age and gender with time to revision for participants undergoing primary total hip (THR) or knee (TKR) replacement in the UK.

DESIGN

Population-based cohort study.

SETTING

Routinely collected primary care data from a representative sample of general practices, including linked data on all secondary care events.

PARTICIPANTS

Population-based cohort study of 63 162 patients with THR and 54 276 with TKR in the UK General Practice Research Database between 1988 and 2011.

PRIMARY AND SECONDARY OUTCOMES

Risk of THR and TKR revision associated with BMI, age and gender, after adjusting for the competing risk of death.

RESULTS

The 5-year cumulative incidence rate for THR was 2.2% for men and 1.8% for women (TKR 2.3% for men, 1.6% for women). The adjusted overall subhazard ratio (SHR) for patients with THR undergoing subsequent hip revision surgery, with a competing risk of death, were estimated at 1.020 (95% CI 1.009 to 1.032) per additional unit (kg/m(2)) of BMI, 1.23 (95% CI 1.10 to 1.38) for men compared with women and 0.970 (95% CI 0.967 to 0.973) per additional year of age. For patients with TKR, the equivalent estimates were 1.015 (95% CI 1.002 to 1.028) for BMI; 1.51 (95% CI 1.32 to 1.73) for gender and 0.957 (95% CI 0.951 to 0.962) for age. Morbidly obese patients with THR had a 65.5% increase (95% CI 15.4% to 137.3%, p=0.006) in the subhazard of revision versus the normal BMI group (18.5-25). The effect for TKR was smaller (a 43.9% increase) and weaker (95% CI 2.6% to 103.9%, p=0.040).

CONCLUSIONS

BMI is estimated to have a small but statistically significant association with the risk of hip and knee revision, but absolute numbers are small. Further studies are needed in order to distinguish between effects for specific revision surgery indications.

Surgical approach and prosthesis fixation in hip arthroplasty world wide

BACKGROUND

Hip arthroplasty is one of the most common and successful surgical procedures worldwide. Component design and materials as well as surgical techniques constantly evolve. There is no consensus among surgeons regarding the ideal surgical approach and method of fixation.

MATERIALS AND METHODS

292 orthopedic surgeons of 10 subspecialties from 57 countries were surveyed on their choice of surgical approach and prosthesis fixation in hip arthroplasty. Their preferences were analyzed according to country of origin, field of expertise and seniority, and compared to current publications.

RESULTS

The response rate was 95-98 %. Surgeons were split between the posterior approach (45 %) and the direct lateral approach (42 %) followed by the anterior approach (10 %) or other (3 %). North American surgeons favored the posterior approach more often than Europeans (69 % compared to 36 %, P < 0.0001) and surgeons from other countries (69 % compared to 45 %, P = 0.01). Sixty-eight percent of all surgeons routinely used noncemented hip prosthesis while 16 % use cemented and 16 % hybrid fixation. Noncemented fixation was preferred among surgeons from Europe and North America compared to other countries (73 % compared to 55 %, P < 0.05). There were no significant differences based on subspecialty, seniority or the number of years of experience.

CONCLUSIONS

The most common surgical approaches in use in hip arthroplasty are posterior and lateral. Anterior approach is used by a minority of orthopedic surgeons for that purpose. Cementing hip prosthesis is falling out of favor among orthopedic surgeons worldwide. The trend toward un-cemented hip arthroplasty is not well supported in the current literature.

A review of current fixation use and registry outcomes in total hip arthroplasty: the uncemented paradox

BACKGROUND

The majority (86%) of THAs performed in the United States are uncemented. This may increase the revision burden if uncemented fixation is associated with a higher risk of revision than other approaches.

QUESTION/PURPOSES

We sought to investigate trends for use of uncemented fixation and to analyze age-stratified risk of revision comparing cemented, hybrid, and uncemented fixation as reported by national hip arthroplasty registries.

METHODS

Data were extracted from the annual reports of seven national hip arthroplasty registries; we included all national registries for which annual reports were available in English or a Scandinavian language, if the registry had a history of more than 5 years of data collection.

RESULTS

Current use of uncemented fixation in primary THAs varies between 15% in Sweden and 82% in Canada. From 2006 to 2010 the registries of all countries reported overall increases in the use of uncemented fixation; Sweden reported the smallest absolute increase (from 10% to 15%), and Denmark reported the greatest absolute increase (from 47% to 68%). Looking only at the oldest age groups, use of uncemented fixation also was increasing during the period. In the oldest age group of each of the registries we surveyed (age older than 65 years for England-Wales; age older than 75 years in three registries), cemented fixation was associated with a lower risk of revision than was uncemented fixation.

CONCLUSIONS

Increasing use of uncemented fixation in THA is a worldwide phenomenon. This trend is paradoxic, given that registry data, which represent nationwide THA outcomes, suggest that cemented fixation in patients older than 75 years results in the lowest risk of revision.

LEVEL OF EVIDENCE

Level II, systematic review. See Guidelines for Authors for a complete description of levels of evidence.

Electronic Data Capture through Total Joint Replacement Registries

The move toward adoption and implementation of electronic health records (EHR) provides an opportunity in the United States to use electronic clinical data (ECD) to better understand patient outcomes and to improve the quality and efficiency of medical care. Within the field of orthopedics, national joint replacement registries have been shown in other countries to improve clinical decision-making and outcomes after joint arthroplasty. Thus, there is increasing interest among U.S. clinical investigators and policymakers to utilize ECD to develop national and regional joint replacement registries. We discuss our experience with integrating electronic data capture and reporting methodology into the California Joint Replacement Registry and American Joint Replacement Registry initiatives. The use of ECD for joint replacement registries will better facilitate multi-stakeholder collaboration, improve the quality of care, reduce medical spending, and foster customized evidence-based clinical decision-making.

Microfracture for acetabular chondral defects in patients with femoroacetabular impingement: results at second-look arthroscopic surgery

BACKGROUND

Microfracture is a proven technique to treat articular cartilage defects in the knee. However, there is little evidence in the literature to confirm the ability of microfracture to produce repair tissue in the hip joint.

PURPOSE

The purpose of this study was to report the macroscopic and microscopic appearances of repair tissue after microfracture performed at hip arthroscopic surgery for isolated full-thickness acetabular cartilage defects in patients with femoroacetabular impingement (FAI).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty patients who underwent arthroscopic surgery for FAI had a localized full-thickness acetabular chondral defect treated by microfracture and then underwent a later second-look hip arthroscopic procedure. The size of the full-thickness defect was measured at the primary arthroscopic procedure. A visual assessment of the extent and quality of repair tissue was performed at second-look arthroscopic surgery. Two patients also had a biopsy of the repair tissue, which was studied histologically.

RESULTS

At an average follow-up of 17 months, 19 of the 20 patients had a mean fill of 96% ± 7% with macroscopically good quality repair tissue. One patient had only a 25% fill with poor quality repair tissue. Histologically, the tissue was found to be primarily fibrocartilage with some staining for type II collagen in the region closest to the bone.

CONCLUSION

Microfracture in the hip appears to be an effective technique that produces excellent coverage of the defect with good quality repair tissue on visual inspection and microscopic examination at an average follow-up of 17 months.