Einfach- und doppeltbeschichtete STAR-Sprunggelenkprothesen

Revision of total ankle arthroplasty: Survival and medium-term functional results

BACKGROUND

The objective of this study was to analyze the results and survivorship of total ankle arthroplasty (TAA) revision surgery with standard (Salto Talaris®) or revision (Salto Talaris XT®) implants.

METHODS

Between January 2005 and December 2017, all patients undergoing TAA revision at our hospital were included. Indications for revision, type of surgery performed, improvement in function assessed with the AOFAS score, occurrence of complications and implant survival at last follow-up were analyzed.

RESULTS

In the end, 25 TAA patients who had undergone revision (11 unipolar, 14 bipolar) were included. The mean follow-up time was 5.1 ± 1.9 years. At the last follow-up, function was improved compared to the preoperative AOFAS score (51.3 ± 17.5 vs. 83.5 ± 10.1; p < .001), but not plantar flexion (17.5 ± 5.7 vs. 15.4 ± 7.1; p = 0.28) or dorsal flexion (7 ± 5.6 vs. 8.3 ± 4.9; p = 0.3). Complications occurred in six patients (24 %) that led to reoperation: three infections, one lateral impingement, one implant malposition, and one hindfoot alignment disorder. At the last follow-up, implant survival was 96 %, but the probability of survival without reoperation was 78.7 ± 8.5 % at 4 years.

CONCLUSION

TAA revision by arthroplasty is feasible, produces good functional results in the medium term, but has a high risk of complications. The challenge of revision TAA is managing the loss of bone stock and anchoring the new implants.

Long-term follow-up of Bologna-Oxford (BOX) total ankle arthroplasty

PURPOSE

The purpose of this retrospective study was to evaluate the long-term results with a minimum of ten years follow-up of primary Bologna-Oxford (BOX) TAA.

METHODS

Between December 2004 and December 2009, 80 patients (82 ankles) underwent a primary BOX TAA performed by a single senior surgeon, expert in foot and ankle surgery. Pain and functional outcomes were analysed using Visual Analogue Scale (VAS) for pain, American Orthopaedic Foot & Ankle Society (AOFAS) scoring system, Foot Functional Index Disability and Pain (FFI-Disability, FFI-Pain) score for comparative analysis.

RESULTS

A total of 52 patients (54 implants) in a cohort of 80 (82 implants) were examined at a minimum ten years follow-up. Twenty implants out of 54 underwent implant failure (37 %) and 34 patients were enrolled in the present study. The mean VAS for pain decreased significantly from 8.5 ± 1.2 to 2.9 ± 2.2 (p<0.01) and the mean AFOAS score changed from 28.6 ± 11.8 pre-operatively to 72.7 ± 16.9 (p<0.01) at last follow-up. Ninety-seven percent was satisfied with a mean FFI-Disability score that improved from 77.6 ± 19.3 to 26.7 ± 25.4 (p<0.01) and FFI-Pain score that decreased from 76.2 ± 14.2 to 31.4 ± 25.6 (p<0.01). We calculated post-operative alignment using alpha, beta and gamma angles with no difference at long-term follow-up. The survival rate of the implant was 66% at ten years of follow-up.

CONCLUSIONS

Our data suggest that BOX TAA is an implant with a good patient satisfaction rate at long-term follow-up; therefore, it is a valid option to increase the quality of life in subjects with end-stage osteoarthritis; however, long-term survivorship is unsatisfactory when compared to modern knee and hip implant.

Survival Analysis of the Single- and Double-Coated STAR Ankle up to 20 Years: Long-Term Follow-up of 324 Cases From the Swedish Ankle Registry

BACKGROUND

The Scandinavian Total Ankle Replacement (STAR) has been used widely in Europe and more recently in the United States. We studied the results of the single-coated and the double-coated STAR with long-term follow-up.

METHODS

All STARs (n = 324) used in Sweden (first implanted in 1993) were included. Prosthetic survival was estimated according to Kaplan-Meier.

RESULTS

The 14-year survival of the single-coated STAR was 0.47 (95% confidence interval [CI], 0.38-0.66), and the 12-year survival of the double-coated STAR was 0.64 (95% CI, 0.57-0.71). Women younger than 60 years with osteoarthritis had a statistically significantly higher risk of revision than men and than patients with other diagnoses.

CONCLUSION

The long-term results of the STAR prosthesis are not encouraging. The results seem to deteriorate by time.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

The outcome of total ankle replacement

We performed a systematic review and meta-analysis of modern total ankle replacements (TARs) to determine the survivorship, outcome, complications, radiological findings and range of movement, in patients with end-stage osteoarthritis (OA) of the ankle who undergo this procedure. We used the methodology of the Cochrane Collaboration, which uses risk of bias profiling to assess the quality of papers in favour of a domain-based approach. Continuous outcome scores were pooled across studies using the generic inverse variance method and the random-effects model was used to incorporate clinical and methodological heterogeneity. We included 58 papers (7942 TARs) with an interobserver reliability (Kappa) for selection, performance, attrition, detection and reporting bias of between 0.83 and 0.98. The overall survivorship was 89% at ten years with an annual failure rate of 1.2% (95% confidence interval (CI) 0.7 to 1.6). The mean American Orthopaedic Foot and Ankle Society score changed from 40 (95% CI 36 to 43) pre-operatively to 80 (95% CI 76 to 84) at a mean follow-up of 8.2 years (7 to 10) (p < 0.01). Radiolucencies were identified in up to 23% of TARs after a mean of 4.4 years (2.3 to 9.6). The mean total range of movement improved from 23° (95% CI 19 to 26) to 34° (95% CI 26 to 41) (p = 0.01).

Our study demonstrates that TAR has a positive impact on patients’ lives, with benefits lasting ten years, as judged by improvement in pain and function, as well as improved gait and increased range of movement. However, the quality of evidence is weak and fraught with biases and high quality randomised controlled trials are required to compare TAR with other forms of treatment such as fusion.

Cite this article: Bone Joint J 2013;95-B:1500–7.

Incidence of revision after primary implantation of the Scandinavian Total Ankle Replacement system: a systematic review

Total ankle replacement was initially popularized in the 1970s as an alternative to ankle arthrodesis for advanced ankle arthritis; however, failures were catastrophic. Current implants show promise, focusing on normal joint anatomy and function with greatly improved materials and more precise surgical technique. Nevertheless, even with advancements in technology and implant engineering, implant failure remains a problem. Debate has existed and published reports vary greatly concerning the incidence of failure and revision of the Scandinavian Total Ankle Replacement system. Thus, a systematic review was performed revealing a 10.7% revision rate at weighted mean follow-up of 64 months.

History of total ankle replacement

Attempts at ankle replacement have existed for at least 50 years. Time has essentially eliminated constrained, cemented, first-generation ankle replacements. Although some two-component, more anatomic, designs are still used with varying success, three-component "mobile bearing" ankle prostheses are winning the race of evolution. Not only have implants change over the years, but also the patients and surgeons. Surgeons specialize, improving their surgical outcomes and expanding the indications for total ankle replacement in technically demanding complex ankles. High-demand, younger patients, but also obese ones, are potential candidates for a total ankle replacement. This article provides a review of the history of total ankle replacement.

Mobile- and fixed-bearing total ankle prostheses: is there really a difference?

Approximately 1% of the world's adult population is affected by ankle osteoarthritis (OA). Therapeutic options include conservative and surgical measures. Because of substantial progress in total ankle replacement, ankle fusion is no longer the "gold standard" therapy for end-stage ankle OA. Various ankle prostheses have been designed and are currently available. This article reviews the in vitro studies addressing the biomechanics and kinematics of the replaced ankle. Furthermore, a systematic literature review was conducted to assess possible differences in clinical outcomes, including prosthesis survivorship and postoperative range of motion between mobile- and fixed-bearing total ankle prostheses.

Tri-component, mobile bearing, total ankle replacement: mid-term functional outcome and survival

Tri-component, mobile bearing, uncemented, total ankle replacements were introduced after the high failure rates of cemented, highly constrained, first-generation, total ankle replacement implants. A total of 30 primary total ankle replacements in 29 patients (20 males and 9 females) were followed up in the present retrospective study for up to 13 (mean 5.1 ± 4) years. The postoperative functional and radiographic outcomes were measured. Failure was defined as revision of either of the components for any reason or conversion of the total ankle replacement to arthrodesis because of debilitating pain that did not resolve after surgery. Of the 29 patients, 2 underwent revision and 1 underwent arthrodesis. All 3 patients had the malpositioned talar implant revised. The mean American Orthopaedic Foot and Ankle Society score was 81 at 1 year postoperatively. Revision of the tibial or talar component for any reason or conversion of the ankle replacement to arthrodesis was considered failure for the survival analysis. Kaplan-Meier analysis showed a 5-year survival rate of 87.6%. The last failure occurred 23.3 months after surgery.

10-year survival of total ankle arthroplasties: a report on 780 cases from the Swedish Ankle Register

BACKGROUND AND PURPOSE

There is an ongoing need to review large series of total ankle replacements (TARs) for monitoring of changes in practice and their outcome. 4 national registries, including the Swedish Ankle Register, have previously reported their 5-year results. We now present an extended series with a longer follow-up, and with a 10-year survival analysis.

PATIENTS AND METHODS

Records of uncemented 3-component TARs were retrospectively reviewed, determining risk factors such as age, sex, and diagnosis. Prosthetic survival rates were calculated with exchange or removal of components as endpoint-excluding incidental exchange of the polyethylene meniscus.

RESULTS

Of the 780 prostheses implanted since 1993, 168 (22%) had been revised by June 15, 2010. The overall survival rate fell from 0.81 (95% CI: 0.79-0.83) at 5 years to 0.69 (95% CI: 0.67-0.71) at 10 years. The survival rate was higher, although not statistically significantly so, during the latter part of the period investigated. Excluding the STAR prosthesis, the survival rate for all the remaining designs was 0.78 at 10 years. Women below the age of 60 with osteoarthritis were at a higher risk of revision, but age did not influence the outcome in men or women with rheumatoid arthritis. Revisions due to technical mistakes at the index surgery and instability were undertaken earlier than revisions for other reasons.

INTERPRETATION

The results have slowly improved during the 18-year period investigated. However, we do not believe that the survival rates of ankle replacements in the near future will approach those of hip and knee replacements-even though improved instrumentation and design of the prostheses, together with better patient selection, will presumably give better results.

A systematic review of outcome and failure rate of uncemented Scandinavian total ankle replacement

PURPOSE

The purpose of this study was to provide cumulative data about the intermediate to long-term outcome of Scandinavian total ankle replacement (STAR) in the literature and to provide a summary of survival rate, implant failure rate and reasons.

METHODS

A comprehensive search for all relevant articles published in English and German from January 1995 to May 2011 was conducted. Two reviewers evaluated each study to determine whether it was eligible for inclusion and, if so, collected data of interest. The intermediate to long-term outcomes were determined. Evidence-based meta-analytic pooling of results across studies was performed to determine survival and failure rates.

RESULTS

Sixteen primary studies with 2,088 implants were identified. The mean American Orthopaedic Foot and Ankle Society (AOFAS) score was 77.8 points, and the mean Kofoed ankle score was 76.4 points. The pooled mean five year survival rate was 85.9% [95% confidence interval (CI) 80.9-90.3], and the pooled mean ten year survival rate was 71.1% (95% CI 60.9-81.5). Pooled failure rate was 11.1% (95% CI 7.6 -14.9), with a mean follow-up time of 52 months; 41% failed within one year of initial operation. The first three reasons associated with implant failure were aseptic loosening (5.2%), malalignment (1.7%) and deep infection (1.0%).

CONCLUSIONS

We found that STAR prosthesis achieved encouraging results in terms of intermediate to long-term outcome. The five and ten year survival rates were acceptable. However, the failure rate was still high. The major reasons for implant failure were aseptic loosening and malalignment. Maybe the increase of surgeons' experience and patient selection could improve outcomes and decrease failure rate.

Revision rates after total ankle arthroplasty in sample-based clinical studies and national registries

BACKGROUND

The aim of this study was to evaluate the outcome of specific implants in total ankle arthroplasty as reported in clinical studies and determined by national registries.

MATERIALS AND METHODS

A structured literature review was conducted regarding sample-based clinical studies and national registry data. To allow for comparative analyses, registry data had to be available for the implants included. These were STAR Ankle, Büchel-Pappas, Hintegra, Mobility, Agility, and Ramses Total Ankle Arthroplasty. The revision rate was used as the main outcome parameter.

RESULTS

On average, the revision rates published in sample-based clinical studies were about half the value found in registries. Implant developers represent a share of almost 50% of the published content and are therefore over-represented in scientific publications. The inventors of STAR Ankle and BP total ankle implants published data which was statistically significantly superior to the outcome achieved in average patients as documented in registries. Irrespective of the implant, the average revision rate to be expected according to the registry data available is 21.8% after 5 years, and 43.5% after 10 years.

CONCLUSION

The average revision rate published in peer-reviewed scientific articles was significantly lower than the outcome achieved according to national arthroplasty registry data, which reflect actual average patient care in the respective countries. Publications by some research groups, particularly by implant inventors, show a deviation from the outcome published by other users and those shown in registry data.

Treatment of ankle osteoarthritis: arthrodesis versus total ankle replacement

While ankle arthrodesis has remained the gold standard treatment for symptomatic primary, secondary, and posttraumatic ankle arthritis, more recently, total ankle replacement (TAR) has seen considerable improvement in terms of biomechanics, function, and complication rates. However, while in the long-term degeneration of the adjacent joints is almost always found on radiographs after ankle arthrodesis, the longevity of TAR is still insufficient and does not match that of total knee and hip joints. The current review article focuses on the treatment of ankle arthritis by means of arthrodesis and TAR.

Medium term follow-up of the AES ankle prosthesis: High rate of asymptomatic osteolysis

BACKGROUND

The AES (Ankle Evolutive System) is a cobalt-chromium three-component ankle prosthesis with a hydroxyapatite coating, similar to the Buechel-Pappas ankle prosthesis, but with some modifications. Our objective was to assess its medium term follow-up results as well as its complications.

METHODS

21 patients (mean age of 57.6 years) were operated by a total ankle arthroplasty (TAA), using the AES implant, according to the standard technique. Only 18 patients were included. The other three patients were excluded from the study: two had been revised for avascular talar necrosis and one patient was happy with her outcome but could not present for logistic reasons at the last follow-up. Indications for surgery included posttraumatic osteoarthritis, primary osteoarthritis, hemochromatosis, rheumatic arthritis and osteoarthritis as a sequel of ankle instability. All patients were analyzed clinically and radiologically. Special attention was given to the presence or not of areas of osteolysis around the implants as well on conventional radiography as on CT-scan imaging, according to a specific protocol.

RESULTS

The mean follow-up was 39.4 months. Average American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score improved from 52.2 preoperatively to 86.6 postoperatively. No intra-operative complications or early complications have been noted. Delayed complications were the following: one valgus malalignment, one recurrent painful anterior heterotrophic bone formation. Above all, we noted on conventional X-ray the presence of osteolysis in 77% (14) of our patients, with a size of 0.5-1cm or greater on conventional X-ray. The most vulnerable area seemed to be the posterior tibial plafond. The four remaining patients did not show any cyst formation on X-ray but did also, just as the other 14 patients, on the CT-scan. CT-scan, on the contrary, found more osteolysis in the body of the talus, underneath the implant, an area masked on conventional X-ray. Only one patient was revised with allograft bone filling of a symptomatic osteolysis, without the need for implant removal.

CONCLUSIONS

This retrospective study shows a high frequency of delayed appearance of osteolysis (77%) in 18 AES total ankle arthroplasties. Fortunately at this moment and considering one revision, this considerable amount of asymptomatic osteolysis could not warrant a durable uncomplicated outcome.

The AES total ankle replacement: A mid-term analysis of 93 cases

BACKGROUND

There are few studies concerning specific total ankle arthroplasties. This study reports mid-term survival data for the AES prosthesis.

METHODS

Ninety-three AES ankle arthroplasties were performed by the senior authors. The mean follow-up was 3.5 years. The 5-year survivorship and also the number of simultaneous procedures, reoperations, additional procedures and revisions are analyzed.

RESULTS

The 5-year survivorship with revision for any reason as end-point was 90%. Simultaneous procedures were performed in 25 patients, deltoid release and subtalar fusion being the most common. There were seven revisions, one due to loosening, and two due to infection, instability and fractures, respectively. Twenty-seven reoperations or additional procedures were performed in 23 patients with a procedure for malleolar impingement being the most common reoperation, and correction of hindfoot varus being the most common reason for an additional procedure.

CONCLUSIONS

The AES total ankle replacement seems to be a reasonably safe procedure in experienced hands.

Total ankle replacement by the Ankle Evolution System

We present the outcomes in 38 consecutive patients who had total ankle replacement using the Ankle Evolution System with a minimum follow-up of four years. Pain and function were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) score and regular standardised anteroposterior and lateral weight-bearing radiographs were obtained. Patient satisfaction and complications were recorded and the survival of the implants was demonstrated by the Kaplan-Meier method.

The mean follow-up was for 57.8 months (48 to 80). The cumulative survival rate at six years was 94.7% (95% confidence interval 80.3 to 98.7). The mean total AOFAS score was 88.1 (53 to 100). The mean score for pain was 35.8 (20 to 40). Ten patients presented with edge-loading of whom nine had corrective surgery. Two ankles were revised, one to an arthrodesis and the other to replace the tibial component. Nine patients showed radiological evidence of osteolysis. They had minimal non-progressive symptoms and further surgery was not undertaken. Nevertheless, the concerns about osteolysis led to the implant being withdrawn by the manufacturer.

The medium-term results of the ankle evolution system ankle replacement are satisfactory with high patient satisfaction, but the rate of osteolysis is of some concern. The long-term benefit of this procedure has yet to be determined.

History and evolution in total ankle arthroplasty

INTRODUCTION

The current study provides an overview of history and evolution in total ankle arthroplasty.

METHODS

We conducted a comprehensive literature search without limitations to language. Information from any source, providing evidence of the use ankle of prostheses (e.g. biomechanical testing, cadaveric implantations or clinical use) was evaluated. Data regarding biomechanical concepts, design considerations, published results (patient numbers, surgical method, follow-up, complications and survival rates) were collected.

RESULTS

Only level IV studies were found. Mobile-bearing prostheses are mainly used in Europe, and fixed-bearing implants are mainly used in the USA. The current designs' failure rate is 10-12% at approximately 5 years. Survival rates vary among different institutions. Increased surgeons' experience is associated with better outcomes.

DISCUSSION

Biomechanical studies and review of previous implant failures has led to the development of a new generation of implants.

CONCLUSIONS

Results show that ankle arthroplasty is a viable alternative for the management of ankle arthritis in selected patients.

Biomechanics of the ankle joint and clinical outcomes of total ankle replacement

Until the 1970s ankle arthrodesis was considered to be the "gold-standard" to treat arthritis. But the low fusion rate of ankle arthrodeses along with the inability to achieve normal range of motion led to the growing interest in the development of total ankle replacements. Though the short-term outcomes were good, their long-term outcomes were not as promising. To date, most models do not exactly mimic the anatomical functionality of a natural ankle joint. Therefore, research is being conducted worldwide to either enhance the existing models or develop new models while understanding the intricacies of the joint more precisely. This paper reviews the anatomical and biomechanical aspects of the ankle joint. Also, the evolution and comparison of clinical outcomes of various total ankle replacements are presented.

A New Zealand national joint registry review of 202 total ankle replacements followed for up to 6 years

BACKGROUND AND PURPOSE

There have been few reports of large series of ankle replacements. The aim of this study was to document and evaluate the early results of a nationwide series of total ankle replacements (TARs) performed using second- and third-generation implants.

METHODS

Records of total ankle replacements performed between February 2000 and November 2005 were retrieved from the New Zealand National Joint Registry and retrospectively reviewed at a mean of 28 months after the primary procedure. At 6 months post surgery, patient scores were generated from questionnaires. Comparisons between patient scores and categorical variables were made using ANOVA. Regression analyses using Cox proportional-hazards modeling were performed to determine predictors of failure. A Kaplan-Meier survivorship curve was used to describe the rate of prosthetic survival.

RESULTS

202 total ankle replacements were performed in 183 patients. 14 prostheses (7%) failed. The overall cumulative 5-year failure-free rate was 86%. An unfavorable patient score at 6 months after the initial procedure turned out to be a good predictor of subsequent failure. The cumulative 5-year failure-free rate was 65% at 5 years for patients with an unfavorable score, and 95% for those who had a favorable patient score. Each 1-point increase in the patient score (i.e. poorer outcome) corresponded to a 5% relative increase in the risk of failure (p < 0.05). In addition, longer operative time for the primary procedure was found in the group of TARs that subsequently failed (p < 0.05).

INTERPRETATION

The National Joint Registry appears to be a useful tool for monitoring the trends in TAR surgery.

The Swedish Ankle Arthroplasty Register: An analysis of 531 arthroplasties between 1993 and 2005

BACKGROUND

Whether or not ankles can be replaced with reasonable safety has been the subject of debate. We present the results of a nationwide series of total ankle arthroplasties.

PATIENTS AND METHODS

All Swedish hospitals that implant or have implanted modern three-component ankle prostheses reported demographic data and date of index and revision surgery to a central register. After the data had been introduced into a database, prosthetic survival rates with exchange or permanent extraction of components as endpoint were calculated.

RESULTS

Of the 531 prostheses implanted, 101 had been revised by June 15, 2006. The overall survival rate at 5 years was 0.78 (95%CI: 0.74-0.82). For the three surgeons who had inserted the majority of the STAR ankles, the survival rates became significantly higher after the first 30 cases had been performed and was estimated to be 0.86 (0.80-0.93) at 5 years. Lower age at index surgery implied increased risk of revision whereas diagnosis or gender did not.

INTERPRETATION

Ankle replacement is a valuable alternative to arthrodesis. However, replacing an ankle is a demanding procedure and the survival is not comparable to that after hip or knee replacement. It is obvious that with increasing experience, the results -- including prosthetic survival -- will improve.

Moderne 3-Komponenten-Sprunggelenkprothesen

Luxation and excessive wear of the mobile bearing in modern three-piece total ankle replacement (TAR) is reported. We conducted a systematic review of studies to explore and discuss the rate and causes of these complications.A systematic review of studies since 2000 showed 26 studies with altogether 1,318 followed up TARs which we analyzed. Of these 1,318 TARs, 188 (14.3%) were revised and 56 (4.2%) complications with the mobile bearing were reported. A total of 39 cases (3%), i.e., 20.7% of all revisions, were revised due to failure of the mobile bearing, including 17 cases with subluxation (1.3%), 15 with asymmetric load of the bearing (1.1%), 10 with fracture of the polyethylene (PE) inlay (0.76%), 7 with massive PE wear (0.53%), and 7 with luxation of the meniscal bearing (0.53%).Complications due to the meniscal mobile bearing in TARs such as luxation, subluxation, massive wear, and fracture of the PE inlay are rare complications. The cause of these complications is regularly not found in the design of this three-piece total ankle replacement. Causes of failure of the mobile bearing are mostly found in incorrect indication, incorrect soft tissue balancing, incorrect positioning of components, implantation in ankles with hindfoot malalignment and ankle instability.