Application and survival curve of total hip arthroplasties: a systematic comparative analysis using worldwide hip arthroplasty registers

Comparison of revision rates and epidemiological data of a single total knee arthroplasty system of different designs (cruciate retaining, posterior stabilized, mobile bearing, and fixed bearing): a meta-analysis and systematic review of clinical trials and national arthroplasty registries

BACKGROUND

This study aimed to meta-analyze epidemiological data, revision rates, and incidences of different designs of a single Total Knee Arthroplasty System and compare these factors across different countries.

METHODS

A systematic review was conducted on clinical studies and arthroplasty registries of ATTUNE TKA from 1999 to 2020. The main endpoints analyzed were revision rates and epidemiological data.

RESULTS

The average age of patients was 67.8 years, with a gender distribution of 60% female and 40% male. The pooled average BMI was 29.4 kg/m2. Eight clinical studies showed a pooled revision rate per 100 observed CY of 0.5 (n = 1343 cases). Cumulative revision rates after 1, 3, and 5 years varied among registries, with the Swiss registry having the highest revision data (after 5 years: 6.3%) and the American registry having the lowest revision data (after 5 years: 1.7%). A comparison of the revision rates of mobile bearing and fixed bearing (41,200 cases) as well as cruciate retaining and posterior stabilized (n = 123,361 cases) showed no significant advantage in the first 5 years after implantation.

CONCLUSION

In conclusion, pooled data from 41,200 cases of TKA with a single Total Knee Arthroplasty System in two arthroplasty registries revealed that there was no significant difference in revision rates between the mobile bearing and fixed bearing design within the first 5 years after implantation. In addition, a comparison of the revision rates in n = 123,361 cases showed no significant advantage for cruciate retaining or posterior stabilized in the first 5 years after implantation.

Development of application and surgical technique of total knee arthroplasties: a systematic comparative analysis using worldwide registers

PURPOSE

The aim was to compare total knee arthroplasty (TKA) between countries with regard to epidemiologic data and surgical technique by the use of worldwide registers and compare findings with a previous report after one decade.

METHODS

A systematic search was carried out in November 2022 and compared to previous reports from 2010. We extracted data regarding implanted TKAs, patients' age distribution, procedure types, fixation and revision rates. After identification of 28 national arthroplasty registers, 8of them, namely Australia, Canada, Denmark, England and Wales, New Zealand, Norway, Scotland and Sweden, offered sufficient data and were included in final analysis.

RESULTS

A large variation was found in the annual number of implantations per 100,000 inhabitants with a range from 77 to 210.2 (mean 132.8). The fixation type varied strongly as well, e.g. over 95% of totally cemented TKAs in Sweden versus 61.2% cemented fixation in Denmark. Another significant difference was the use of patellar resurfacing in TKA, ranging from 47.3% (Canada) using a patellar button in TKA to less than 5% (Sweden). Within the period of one decade, the mean overall number of annual implantations increased (10%), whilst relative number of revisions decreased, the use of cemented TKA decreased from 87 to 74%, and the use of patella button remained largely inhomogeneous.

CONCLUSION

Comparison of arthroplasty registers revealed large differences regarding the annual number of primary TKAs per inhabitant as well as primary TKA procedure types with an increase of annual implantations, decrease of relative number of revisions, and a decrease of the use of cemented systems over the period of one decade.

Constrained metal-on-metal hip arthroplasty: ever heard of a 50-year survival story?

BACKGROUND

The history of total hip arthroplasty dates back to the first half of the twentieth century. Data on hip endoprostheses implanted during the 1960s and 1970s suggest widely varying survival rates of the prosthesis.

CASE

A case of a patient who underwent total hip arthroplasty in 1972 using a Sivash prosthesis, developed in 1956 in the former Soviet Union, is presented in this article. The prosthesis has remained unrevised in the patient's body for 50 years and he continues to be widely free of implant-related symptoms. Despite the constrained metal-on-metal design of the implant, which can lead to adverse reactions to metal debris, no elevated systemic metal ion levels were detected.

CONCLUSION

The likelihood of encountering patients with prosthesis survival beyond 50 years is still rare. Nevertheless, changing demographics and the steadily improving designs and materials of hip endoprostheses may likely result in such cases.

Higher use of fixed-bearing over mobile-bearing and posterior-stabilized over medial pivot designs in total knee arthroplasty (TKA): a systematic comparative analysis using worldwide arthroplasty registers from England and Wales, Australia, Norway, New Zealand, Germany and Switzerland

INTRODUCTION

The aim of this study was to compare the use of mobile-bearing, fixed-bearing, posterior-stabilized (PS) and medial pivot design to describe epidemiological differences and subsequent outcomes.

MATERIALS AND METHODS

A systematic literature search was performed using the NORE website to identify the relevant arthroplasty registers. Inclusion criteria were the following: (1) reports had to be publicly available, (2) reports had to be written in German or English language, (3) differentiation between mobile- and fixed-bearing, posterior-stabilized, and if possible, medial pivot designs had to be possible from the present reports, and (4) data had to be reported for at least three consecutive years and the latest report had to be from the year 2020 to retrieve recent data.

RESULTS

Six registries (England and Wales, Australia, Norway, New Zealand, Germany, Switzerland) offered sufficient data according to the inclusion criteria. In all countries, the dominant type of bearing used for total knee arthroplasty (TKA) was fixed-bearing, with percentages ranging from 60.8% to 84.1% in 2018, 63.6% to 85.7% in 2019 and 66.2% to 87.4% in 2020. A large variation was observed concerning mobile-bearing design, which showed a range from 2.8% to 39.2% in 2018, 2.6% to 36.4% in 2019 and 2.9% to 33.8% in 2020. Some variation was found regarding the use of PS TKA, as its percentage frequency ranged from 9.7% to 29.2% in 2018, 9.8% to 29.4% in 2019 and 10.1% to 28.5% in 2020. Medial pivot design had a share of 9.1% in 2018, 8.6% in 2019 and 8.4% in 2020 in Australia, while it only accounted for 1.4% in 2018, 2.1% in 2019 and 2.5% in 2020 in Germany.

CONCLUSION

The comparison of arthroplasty registers from England and Wales, Australia, Norway, New Zealand, Germany and Switzerland revealed large differences regarding the application of posterior-stabilized designs, but also common ground considering the overwhelming use of fixed-bearing inserts, which, when inserted correctly, eradicate the potential complication of bearing dislocation. Arthroplasty registers offer a real-world clinical perspective with the aim to improve quality and patient safety.

A systematic review of pain outcomes reported by randomised trials of hip and knee arthroplasty

It is difficult to pool results from randomised clinical trials that report different outcomes. We want to develop a core set of pain-related outcomes after total hip or knee arthroplasty, the first stage of which is to systematically review published outcomes. We searched PubMed, Embase and CENTRAL for relevant trials to January 2020. We identified 165 outcomes from 565 trials with 50,668 participants, which we categorised into six domains: pain; analgesic consumption; quality of care; adverse events; mobility; and patient-reported outcome measures. The outcome in each domain reported by most trials was: visual analogue score for pain, 401 (71%); morphine consumption, 212 (38%); length of hospital stay, 166 (29%); nausea or vomiting, 425 (75%); range of motion, 173 (31%); and patient satisfaction score, 181 (32%). A primary outcome was reported in 281 (50%) trials: 101 (18%) trials reported consumption of rescue analgesics and 95 (17%) trials reported pain. We plan to publish a consensus on outcomes that should be reported in postoperative pain trials after hip or knee arthroplasty.

What the Surgeon Can Do to Reduce the Risk of Trunnionosis in Hip Arthroplasty: Recommendations from the Literature

Trunnionosis, defined as wear and corrosion at the head–neck taper connection, is a cause of failure in hip arthroplasty. Trunnionosis is linked to a synergistic combination of factors related to the prosthesis, the patient, and the surgeon. This review presents analytical models that allow for the quantification of the impact of these factors, with the aim of providing practical recommendations to help surgeons minimize the occurrence of this failure mode. A tighter fit reduces micromotion and, consequently, fretting of the taper connection. The paramount parameters controlling the fixation force are the coefficient of friction and the impaction force. The influence of the head diameter, as well as of the diameter and angle of the taper, is comparatively small, but varus alignment of the taper and heads with longer necks are unfavourable under physiologic loads. The trunnion should be rinsed, cleaned, and dried carefully, while avoiding any contamination of the bore—the female counterpart within the head—prior to assembly. Biological debris, and even residual water, might critically reduce the fixation of the taper connection between the head and the neck. The impaction force applied to the components should correspond to at least two strong blows with a 500 g hammer, striking the head with an ad hoc impactor aligned with the axis of the taper. These strong blows should correspond to a minimum impaction force of 4000 N.

[What can we learn in future from the data of the German Arthroplasty Registry (EPRD) in comparison to other registries?]

The German Arthroplasty Registry (EPRD) was founded in 2010 and has been in full operation since 2014. Previous attempts at a systematic data collection of elective and non-elective knee and hip replacement in Germany failed mainly because of the long-term lack of funding. The EPRD is an interdisciplinary collaborative partnership between the German Association of Orthopedics and Orthopedic Surgery (DGOOC), all implant manufacturers of the German Medical Technology Association (BVMed), health insurers (AOK and the Association of Additional Healthcare Insurance) and hospitals (German Hospital Federation). As part of this cooperation a worldwide unique implant database has been set up, which includes all relevant components and a detailed description of implant specifications. This implant library enables a detailed evaluation of implant survival, revision rates and possible inferior implant performance of knee and hip replacements in Germany. At the end of 2015 the EPRD encompassed over 200,000 registered operations. Due to the high number of hip and knee arthroplasties in Germany with many different implants from different manufacturers there will be a rapid growth of data that are available for a national and also international comparison of the results.

Is a questionnaire and radiograph-based follow-up model for patients with primary hip and knee arthroplasty a viable alternative to traditional regular outpatient follow-up clinic?

AIMS

Increasing demand for total hip and knee arthroplasty (THA/TKA) and associated follow-up has placed huge demands on orthopaedic services. Feasible follow-up mechanisms are therefore essential.

METHODS

We conducted an audit of clinical follow-up decision-making for THA/TKA based on questionnaire/radiograph review compared with local practice of Arthroplasty Care Practitioner (ACP)-led outpatient follow-up. In all 599 patients attending an ACP-led THA/TKA follow-up clinic had a pelvic/knee radiograph, completed a pain/function questionnaire and were reviewed by an ACP. An experienced orthopaedic surgeon reviewed the same radiographs and questionnaires, without patient contact or knowledge of the ACP's decision. Each pathway classified patients into: urgent review, annual monitoring, routine follow-up or discharge.

RESULTS

In total, 401 hip and 198 knee patients were included. There was substantial agreement between the ACP and surgeon for both hip (kappa = 0.69, 95% confidence interval (CI) 0.62 to 0.76) and knee (kappa = 0.81, 95% CI 0.74 to 0.88). Positive agreement was very high for discharge and routine follow-up; however the ACP was more likely to select annual monitoring and the surgeon urgent review.

DISCUSSION

Review of the questionnaire/radiograph together identified all patients in need of increased surveillance, with good agreement for on-going patient management. However, review of the radiograph or questionnaire alone missed some patients with potential problems. A radiograph in conjunction with a questionnaire as a review may represent a cost effective THA/TKA follow-up mechanism.

TAKE HOME MESSAGE

A questionnaire and radiograph-based remote review may represent a cost-effective total joint arthroplasty follow-up mechanism; thereby reducing the considerable burden that follow-up currently places on the NHS.

In vitro osteogenic capacity of bone marrow MSCs from postmenopausal women reflect the osseointegration of their cementless hip stems

Age-related dysfunction of mesenchymal stromal cells (MSCs) is suggested as a main cause of altered bone repair with aging. We recently showed that in postmenopausal women undergoing cementless total hip arthroplasty (THA) aging, low bone mineral density (BMD) and age-related geometric changes of the proximal femur are risk factors for increased early migration and delayed osseointegration of the femoral stems. Extending these analyses, we have here explored how the in vitro osteogenic capacity of bone marrow MSCs from these patients reflects implant osseointegration, representing the patient's in vivo bone healing capacity. A total of 19 postmenopausal women with primary hip osteoarthritis (mean age 65 years, range 50–78) and well-defined bone quality underwent successful preoperative in vitro analysis of osteogenic capacity of iliac crest bone marrow MSCs as well as two-year radiostereometric (RSA) follow-up of femoral stem migration after cementless THA. In patients with MSCs of low osteogenic capacity, the magnitude of cumulative stem subsidence after the settling period of three months was greater (p = 0.028) and the time point for translational osseointegration was significantly delayed (p = 0.030) compared to patients with MSCs of high osteogenic capacity. This study suggests that patients with MSCs of low in vitro osteogenic capacity may display increased stem subsidence after the settling period of 3 months and thereby delayed osseointegration. Our study presents a novel approach for studying the biological progress of hip implant osseointegration and to verify the impact of decreased MSCs function, especially in patients with age-related dysfunction of MSCs and bone healing capacity.

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Age-related dysfunction of MSCs is a main cause of altered bone repair with aging.

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MSCs play a critical role in osseointegration of cementless hip replacement.

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We explored if hip implant osseointegration in postmenopausal women is mirrored by in vitro osteogenic ability of their MSCs.

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Low osteogenic differentiation of MSCs correlated with increased implant migration.

Total hip replacement and surface replacement for the treatment of pain and disability resulting from end-stage arthritis of the hip (review of technology appraisal guidance 2 and 44): systematic review and economic evaluation

BACKGROUND

Total hip replacement (THR) involves the replacement of a damaged hip joint with an artificial hip prosthesis. Resurfacing arthroplasty (RS) involves replacement of the joint surface of the femoral head with a metal surface covering.

OBJECTIVES

To undertake clinical effectiveness and cost-effectiveness analysis of different types of THR and RS for the treatment of pain and disability in people with end-stage arthritis of the hip, in particular to compare the clinical effectiveness and cost-effectiveness of (1) different types of primary THR and RS for people in whom both procedures are suitable and (2) different types of primary THR for people who are not suitable for hip RS.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, The Cochrane Library, Current Controlled Trials and UK Clinical Research Network (UKCRN) Portfolio Database were searched in December 2012, with searches limited to publications from 2008 and sample sizes of ≥ 100 participants. Reference lists and websites of manufacturers and professional organisations were also screened.

REVIEW METHODS

Systematic reviews of the literature were undertaken to appraise the clinical effectiveness and cost-effectiveness of different types of THR and RS for people with end-stage arthritis of the hip. Included randomised controlled trials (RCTs) and systematic reviews were data extracted and risk of bias and methodological quality were independently assessed by two reviewers using the Cochrane Collaboration risk of bias tool and the Assessment of Multiple Systematic Reviews (AMSTAR) tool. A Markov multistate model was developed for the economic evaluation of the technologies. Sensitivity analyses stratified by sex and controlled for age were carried out to assess the robustness of the results.

RESULTS

A total of 2469 records were screened of which 37 were included, representing 16 RCTs and eight systematic reviews. The mean post-THR Harris Hip Score measured at different follow-up times (from 6 months to 10 years) did not differ between THR groups, including between cross-linked polyethylene and traditional polyethylene cup liners (pooled mean difference 2.29, 95% confidence interval -0.88 to 5.45). Five systematic reviews reported evidence on different types of THR (cemented vs. cementless cup fixation and implant articulation materials) but these reviews were inconclusive. Eleven cost-effectiveness studies were included; four provided relevant cost and utility data for the model. Thirty registry studies were included, with no studies reporting better implant survival for RS than for all types of THR. For all analyses, mean costs for RS were higher than those for THR and mean quality-adjusted life-years (QALYs) were lower. The incremental cost-effectiveness ratio for RS was dominated by THR, that is, THR was cheaper and more effective than RS (for a lifetime horizon in the base-case analysis, the incremental cost of RS was £11,284 and the incremental QALYs were -0.0879). For all age and sex groups RS remained clearly dominated by THR. Cost-effectiveness acceptability curves showed that, for all patients, THR was almost 100% cost-effective at any willingness-to-pay level. There were age and sex differences in the populations with different types of THR and variations in revision rates (from 1.6% to 3.5% at 9 years). For the base-case analysis, for all age and sex groups and a lifetime horizon, mean costs for category E (cemented components with a polyethylene-on-ceramic articulation) were slightly lower and mean QALYs for category E were slightly higher than those for all other THR categories in both deterministic and probabilistic analyses. Hence, category E dominated the other four categories. Sensitivity analysis using an age- and sex-adjusted log-normal model demonstrated that, over a lifetime horizon and at a willingness-to-pay threshold of £20,000 per QALY, categories A and E were equally likely (50%) to be cost-effective.

LIMITATIONS

A large proportion of the included studies were inconclusive because of poor reporting, missing data, inconsistent results and/or great uncertainty in the treatment effect estimates. This warrants cautious interpretation of the findings. The evidence on complications was scarce, which may be because of the absence or rarity of these events or because of under-reporting. The poor reporting meant that it was not possible to explore contextual factors that might have influenced study results and also reduced the applicability of the findings to routine clinical practice in the UK. The scope of the review was limited to evidence published in English in 2008 or later, which could be interpreted as a weakness; however, systematic reviews would provide summary evidence for studies published before 2008.

CONCLUSIONS

Compared with THR, revision rates for RS were higher, mean costs for RS were higher and mean QALYs gained were lower; RS was dominated by THR. Similar results were obtained in the deterministic and probabilistic analyses and for all age and sex groups THR was almost 100% cost-effective at any willingness-to-pay level. Revision rates for all types of THR were low. Category A THR (cemented components with a polyethylene-on-metal articulation) was more cost-effective for older age groups. However, across all age-sex groups combined, the mean cost for category E THR (cemented components with a polyethylene-on-ceramic articulation) was slightly lower and the mean QALYs gained were slightly higher. Category E therefore dominated the other four categories. Certain types of THR appeared to confer some benefit, including larger femoral head sizes, use of a cemented cup, use of a cross-linked polyethylene cup liner and a ceramic-on-ceramic as opposed to a metal-on-polyethylene articulation. Further RCTs with long-term follow-up are needed.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013003924.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A new universal, standardized implant database for product identification: a unique tool for arthroplasty registries

INTRODUCTION

Every joint registry aims to improve patient care by identifying implants that have an inferior performance. For this reason, each registry records the implant name that has been used in the individual patient. In most registries, a paper-based approach has been utilized for this purpose. However, in addition to being time-consuming, this approach does not account for the fact that failure patterns are not necessarily implant specific but can be associated with design features that are used in a number of implants. Therefore, we aimed to develop and evaluate an implant product library that allows both time saving barcode scanning on site in the hospital for the registration of the implant components and a detailed description of implant specifications.

MATERIALS AND METHODS

A task force consisting of representatives of the German Arthroplasty Registry, industry, and computer specialists agreed on a solution that allows barcode scanning of implant components and that also uses a detailed standardized classification describing arthroplasty components. The manufacturers classified all their components that are sold in Germany according to this classification. The implant database was analyzed regarding the completeness of components by algorithms and real-time data.

RESULTS

The implant library could be set up successfully. At this point, the implant database includes more than 38,000 items, of which all were classified by the manufacturers according to the predefined scheme. Using patient data from the German Arthroplasty Registry, several errors in the database were detected, all of which were corrected by the respective implant manufacturers.

CONCLUSIONS

The implant library that was developed for the German Arthroplasty Registry allows not only on-site barcode scanning for the registration of the implant components but also its classification tree allows a sophisticated analysis regarding implant characteristics, regardless of brand or manufacturer. The database is maintained by the implant manufacturers, thereby allowing registries to focus their resources on other areas of research. The database might represent a possible global model, which might encourage harmonization between joint replacement registries enabling comparisons between joint replacement registries.

Metal ions as inflammatory initiators of osteolysis

Osteolysis and aseptic loosening currently contribute 75 % of implant failures. Furthermore, with over four million joint replacements projected to be performed in the United States annually, osteolysis and aseptic loosening may continue to pose a significant morbidity. This paper reviews the osteolysis cascade leading to osteoclast activation and bone resorption at the biochemical level. Additionally, the metal ion release mechanism from metallic implants is elucidated. Even though metal ions are not the predominating initiator of osteolysis, they do increase the concentration of key inflammatory cytokines that stimulate osteoclasts and prove to be a contributor to osteolysis and aseptic loosening. Osteolysis is a competitive mechanism among a number of biological reactions, which includes debris release, macrophage and osteoclast activation, an inflammatory response as well as metal ion release. Pharmacological therapy for component loosening has also been reviewed. A non-surgical treatment of osteolysis has not been found in the literature and thus may become an area of future research. Even though this research is warranted, comprehensively understanding the immune response to orthopedic implants and their metallic ions, and thus, creating improved prostheses appears to be the most cost-effective approach to decrease the morbidity related to osteolysis and to design implants with greater longevity. The ionic forms, cytokines, toxicity, gene expression, biological effects, and hypersensitivity responses of metallic elements from metal implants are summarized as well.

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.

Failure modes for total ankle arthroplasty: a statistical analysis of the Norwegian Arthroplasty Register

BACKGROUND

It is imperative to understand the most common failure modes of total ankle arthroplasty (TAA) to appropriately allocate the resources, healthcare costs, enhancing surgical treatment methods, and improve design and longevity of the implant. The objective of this study was to investigate the primary mode or modes of failure (Loose talar component, loose tibial component, dislocation, instability, misalignment, deep infection, Fracture (near implant), Pain, defect polyethylene (PE), other, and missing information) of TAA implants, so these failure mode/modes can be targeted for future improvement.

METHODS

The Norwegian Total Hip Arthroplasty Register 2008 was chosen as the primary source of data since the register have been in existence for 20 years and also gives more specific failure modes than other registries. Tukey-Kramer method was applied to Norwegian Arthroplasty Register.

RESULTS

After the application of the Tukey-Kramer method, it is evident that there is no significant difference between any of the failure modes that are pertinent to the ankle. However, there is significant evidence that the number of ankle arthroplasties are increasing with time.

CONCLUSIONS

Since there is no statistical evidence showing which failure mode contributes most to revision surgeries, it is concluded that more information/data is needed to further investigate failure modes in ankle arthroplasties. Since the numbers of such surgeries are increasing, sufficient data should become available in time.

Prosthetic joint infection following total hip replacement: results of one-stage versus two-stage exchange

PURPOSE

Prosthetic hip joint infection remains a challenging socio-economic problem. Curative treatment is usually a one- or two-stage revision surgery, but neither of these options has yet emerged as the treatment of choice. The aim of this study was to evaluate which of these methods produced superior outcomes.

METHODS

A retrospective study was performed including 92 patients with deep infections after implantation of primary total hip arthroplasty (THA) who had undergone either one-stage or two-stage revision surgery at a single centre. Infections were classified according to McPherson and we evaluated the rate of persisting infection or reinfection after surgical intervention.

RESULTS

The two-stage revision surgery revealed superior outcomes for the analysed infection categories compared to the one-stage procedure except for the least serious category of infections (i.e. McPherson Stage I/A/1, early postoperative infection, no systemic comorbidities, local status uncompromised). Eradication of prosthetic infection was achieved in 94.5 % (n = 52) within the group of two-stage exchange, and 56.8 % (n = 21) of patients treated with a one-stage procedure. Outcome of patients following a one-stage or a two-stage exchange was overall significantly different with p < 0.001. Further deviations between the described two procedures were noted in the subgroups following the classification described by McPherson.

CONCLUSIONS

Our results indicate superiority of two-stage revision surgery in case of serious infections. The authors believe that decisions on the surgical approach for the treatment of deep prosthesis infections should be made on the basis of standardized staging systems.

The incidence of implant fractures after total hip arthroplasty

PURPOSE

Implant fractures after total hip arthroplasty (THA) are considered as rare in clinical practice. Nevertheless they are relevant complications for patients, physicians, and the public health system leading to high socioeconomic burdens. The aim of this study was to assess the incidence of fractures after THAs in a comparative analysis of clinical studies and worldwide arthroplasty register datasets.

METHODS

We calculated the pooled incidence of revision operations after fractures of THAs in a comparison of clinical studies published in Medline-listed journals and annual reports of worldwide arthroplasty registers in a structured literature analysis based on a standardised methodology.

RESULTS

Included clinical studies (sample-based datasets) were mono-centre trials comprising a cumulative number of approximately 70,000 primary implantations whereas worldwide national arthroplasty register datasets referred to 733,000 primary implantations, i.e. approximately ten times as many as sample-based datasets. In general, sample-based datasets presented higher revision rates than register datasets with a maximum deviation of a 14.5 ratio for ceramic heads, respectively. The incidence of implant fractures in total hip arthroplasty in pooled worldwide arthroplasty register datasets is 304 fractures per 100,000 implants. In other words, one out of 323 patients has to undergo revision surgery due to an implant fracture after THA in their lifetime.

CONCLUSIONS

Implant fractures in total hip arthroplasty occur in a relevant number of patients. The authors believe that comprehensive arthroplasty register datasets allow more general evaluations and conclusions on that topic in contrast to clinical studies.

Ten year results of the collum femoris preserving total hip replacement: a prospective cohort study of seventy five patients

PURPOSE

The collum femoris preserving (CFP) uncemented prosthesis has a bone-preserving, high subcapital neck resection and a short anatomical stem. The ideal arthroplasty option in the younger, active patient is a subject of some debate. We evaluated midterm outcomes of the CFP in this patient population.

METHODS

A prospective, consecutive cohort of 75 CFP total hip replacement (THR) patients with a mean age of 52 years was followed for a mean of 9.3 years. Patients were assessed using the Harris Hip Score (HHS). Pain was assessed using a visual analogue scale (VAS) and activity levels using the University of California, Los Angeles (UCLA) score. Radiographs were evaluated for evidence of loosening. Survivorship was calculated with an endpoint of revision for aseptic loosening or radiographic evidence of loosening.

RESULTS

Mean HHS improved from a mean of 50 pre-operatively to 91 (p < 0.001) postoperatively. Mean pain score was 1, mean patient satisfaction was 9 and mean UCLA score was 6. Two acetabular components were revised for aseptic loosening; no stem required revision. Radiographically, no cases had evidence of loosening. Survivorship was 96.8 % for the acetabular component and 100 % for the stem at ten years. Three patients died from unrelated causes, and five were lost to follow-up.

CONCLUSIONS

Bone-preserving hip replacement has increased in popularity as hip replacement in younger and more active individuals increases. The CFP prosthesis has excellent midterm clinical function and survival and provides high levels of satisfaction in young patients.

Titanium particles up-regulate the activity of matrix metalloproteinase-2 in human synovial cells

PURPOSE

Wear debris particle-induced osteolysis and subsequent aseptic loosening is one of the major causes of failure of total joint replacement. The purpose of this study was to investigate the effect of titanium implant material and inflammatory cytokines on human synovial cells and the development to osteolysis and aseptic loosening.

METHODS

This study investigated the effect of titanium implant material on the ECM-degraded MMP-2 in human synovial cells and analyzed the contribution of synovial cells in osteolysis and aseptic loosening.

RESULTS

When human synovial cells are exposed to titanium materials, MMP-2 activity is induced by 1.72 ± 0.14-fold with Ti disc and 3.95 ± 0.10-fold with Ti particles, compared with that of the controls, respectively. Inflammatory cytokines TNFα and IL-1β are also shown to induce MMP-2 activity by 3.65 ± 0.28-fold and 6.76 ± 0.28-fold, respectively. A combination of Ti particles and cytokines induces MMP-2 activities to a higher level (10.54 ± 0.45-fold). Inhibitors of various signal pathways involved in MMP-2 reverse Ti particle-induced MMP-2 activities.

CONCLUSIONS

Synovial cells surrounding the bone-prosthesis interface may contribute to production of MMP-2, and NFκB inhibitors may be explored as potential therapeutics to alleviate wear debris-induced osteolysis and aseptic loosening.

Comparative pooled survival and revision rate of Austin-Moore hip arthroplasty in published literature and arthroplasty register data

The aim was to evaluate the pooled survival and revision rate of Austin-Moore hip arthroplasty (AMHA) in published literature and arthroplasty register data. A comprehensive literature analysis of clinical publications and register reports was conducted with the main endpoints revision surgery and revision rate. Sixteen relevant clinical studies have been found to significantly underestimate revision rates by a ratio of 2.15 compared to register data sets. The medium-term outcome of AMHA showed significantly worse outcomes than the use of other bipolar implants, or modular cervicocephalic prostheses and data of journal publications on revision rates deviate significantly from data of arthroplasty registers.

Application and surgical technique of total knee arthroplasties: a systematic comparative analysis using worldwide registers

PURPOSE

The aim of this study was to compare total knee arthroplasty (TKA) procedures between different countries with regard to epidemiological data and surgical technique by reference to the worldwide arthroplasty registers.

METHODS

A systematic search was carried out using the EFORT website to identify the relevant arthroplasty registers. We extracted data with respect to the number of implanted TKAs, patients' age distribution, procedure types, and revision rates. After identification of 28 national arthroplasty registers, 11 offered sufficient data regarding the above mentioned parameters and were therefore included in the final analysis.

RESULTS

A large variation was found in the annual number of primary TKA implantations per inhabitant with a reported range from 30 to 199 per 100,000 (mean 106). The fixation method varied strongly between the different registers as well, e.g. 90 % of totally cemented TKAs in Sweden, England and Wales, Slovakia, and New Zealand versus 54 % cemented fixation in Australia. Another significant difference between included countries was observed with respect to the use of patellar resurfacing in TKA. Whilst the Danish knee arthroplasty register reports a percentage of 72 % using a patellar button in TKA the register from Norway reports only a minority of 2 %.

CONCLUSIONS

The comparison of arthroplasty registers revealed large differences regarding the annual number of primary TKAs per inhabitant and primary TKA procedure types. These variations may be explained by several factors such as patient demographics (prevalence of osteoarthritis) and national conditions such as healthcare systems (insurance status), number or availability of performing surgeons, medical facilities and surgeon-dependent factors such as definition of indications, education, tradition and experience.

Pooled outcome of total hip arthroplasty with the CementLess Spotorno (CLS) system: a comparative analysis of clinical studies and worldwide arthroplasty register data

PURPOSE

Our aim was to elucidate the pooled outcome of the CementLess Spotorno (CLS) system in total hip arthroplasty (THA).

METHODS

We compared the outcome of clinical inventor studies, independent clinical studies, and worldwide register data. The main endpoints for analysis were revision rates.

RESULTS

Twenty clinical studies were evaluated and, with one exception, overall found revision rates largely in line with register data. Revision rates (revisions per 100 observed component years) range from 0.15 (inventor study) to 0.28 (independent studies) and 0.43 (register datasets).

CONCLUSION

Data of journal publications and register datasets using the CLS system do not differ significantly with respect to revision rates. Only the initial inventor study reports a revision rate three times lower than in pooled worldwide register datasets.

Modular acetabular reconstructive cup in acetabular revision total hip arthroplasty at a minimum ten year follow-up

PURPOSE

Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases.

METHODS

We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky's type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips).

RESULTS

Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81-98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening.

CONCLUSIONS

The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.