Incidence of revision after primary implantation of the Salto ® mobile version and Salto Talaris ™ total ankle prostheses: a systematic review

Intermediate to long-term clinical outcomes and survival analysis of the Salto Mobile Bearing total ankle prothesis

INTRODUCTION

Osteoarthritis of the ankle is a major burden to affected patients. While tibio-talar arthrodesis has been the gold-standard regarding the treatment of osteoarthritis of the ankle joint for many years, at present total ankle arthroplasty (TAA) provides appealing clinical outcomes and is continually gaining popularity. The aim of this study was to evaluate the intermediate- to long-term clinical outcome including the survival rate of Salto Mobile Bearing TAA (Tonier SA, Saint Ismier, France).

MATERIAL AND METHODS

In this retrospective study intermediate- to long-term outcomes measures [Ankle Range of Motion (ROM), American Orthopaedic Foot and Ankle Score (AOFAS score) and survival rate] of 171 consecutive TAA were analysed and compared before and after surgery. Revision was defined as secondary surgery with prothesis component removal, while reoperation was defined as a non-revisional secondary surgery involving the ankle.

RESULTS

At a mean follow-up (FU) period of 7.2 ± 2.7 years (range 2.0 to 14.1 years) there was a significant improvement in ankle ROM (total ROM improved from 25.0° ± 15.0° to 28.7° ± 11.3°, p = 0.015; plantarflexion improved from 18.4° ± 11.7° to 20.6° ± 8.2°, p = 0.044; dorsiflexion improved from 6.6° ± 5.7° to 8.1° ± 4.9°, p = 0.011). AOFAS score increased significantly by 41 ± 15 points after surgery (43.3 ± 11.1 before and 84.3 ± 12.0 after surgery, p < 0.001). Overall survival rate within the FU was 81.3% (95% CI 75.3% to 87.3%) with any secondary surgery, 89.9% (95% CI 84.1% to 93.6%) with revision and 93.6% (95% CI 89.8% to 97.3%) with reoperation as endpoint.

CONCLUSION

This study endorses the previously reported appealing intermediate- to long-term outcomes of the Salto Mobile Bearing TAA. There was a significant increase in ROM and AOFAS score as well as decent implant survival at final FU.

Ten-year revision rates of contemporary total ankle arthroplasties equal 22%. A meta-analysis

BACKGROUND

The National Institute for Health and Care Excellence criterion for hip replacements is a (projected) revision rate of less than 5% after 10 years. No such criterion is available for ankle prostheses. The objective of the current study is to compare survival rates of contemporary primary ankle prostheses to the hip-benchmark.

METHODS

The PRISMA methodology was used. Eligible for inclusion were clinical studies reporting revision rates of currently available primary total ankle prostheses. Data was extracted using preconstructed forms. The total and prosthesis-specific annual revision rate was calculated.

RESULTS

Fifty-seven articles of eight different ankle prostheses were included (n = 5371), totaling 513 revisions at an average 4.6 years of follow-up. An annual revision rate of 2.2 was found (i.e. an expected revision rate of 22% at 10 years).

CONCLUSIONS

The expected 10-year revision rate of contemporary ankle prostheses is lower than the current benchmark for hip prostheses.

The motion between components in a mobile-bearing total ankle replacement measured by cone-beam CT scanning

BACKGROUND

To measure the motion of polyethylene insert and implant components of mobile-bearing total ankle replacement (TAR) by cone-beam CT scanning.

METHODS

10 TAR patients with high amount of clinical motion after the CCI implant (Ceramic Coated Implant; Wright Medical Technology, Arlington, TN, USA) with average age at operation 64,3 years (range 47-84) and average clinical total range of motion 42 degrees (range 35-55) were included.

RESULTS

The average total range of motion between the insert and the tibial component was 0.8mm (range 0-2) in the coronal plane, and 2.9mm (range 1-6) in the sagittal plane. There was wide variation in the axial rotation measurements between the components.

CONCLUSION

We found measurable motion between the mobile-bearing insert and the tibial component in all planes. The relevance of this motion to the function and long-term survival of the TAR remains to be determined.

Three-Year Rates of Reoperation and Revision Following Mobile Versus Fixed-Bearing Total Ankle Arthroplasty: A Cohort of 302 Patients with 2 Implants of Similar Design

BACKGROUND

Currently, the implants utilized in total ankle arthroplasty (TAA) are divided between mobile-bearing 3-component and fixed-bearing 2-component designs. The literature evaluating the influence of this mobility difference on implant survival is sparse. The purpose of the present study was therefore to compare the short-term survival of 2 implants of similar design from the same manufacturer, surgically implanted by the same surgeons, in fixed-bearing or mobile-bearing versions.

METHODS

All patients were enrolled who underwent TAA with either the mobile-bearing Salto (Tornier and Integra) or the fixed-bearing Salto Talaris (Integra) in 3 centers by 2 surgeons between January 2004 and March 2018. All patients who underwent TAA from January 2004 to April 2013 received the Salto implant, and all patients who underwent TAA after November 2012 received the Salto Talaris implant. The primary outcome was time, within 3 years, to first all-cause reoperation, revision of any metal component, and revision of any component, including the polyethylene insert. Secondary outcomes included the frequency, cause, and type of reoperation.

RESULTS

A total of 302 consecutive patients were included, of whom 171 received the mobile-bearing and 131 received the fixed-bearing implant. The adjusted hazard ratio for all-cause reoperation was 1.42 (95% confidence interval [CI], 0.67 to 3.00; p = 0.36); for component revision, 3.31 (95% CI, 0.93 to 11.79; p = 0.06); and for metal component revision, 2.78 (95% CI, 0.58 to 13.33; p = 0.20). A total of 31 reoperations were performed in the mobile-bearing group compared with 14 in the fixed-bearing group (p = 0.07). More extensive reoperation procedures were performed in the mobile-bearing group.

CONCLUSIONS

With the largest comparison of 2 implants of similar design from the same manufacturer, the present study supports the use of a fixed-bearing design in terms of short-term failure. We found a 3-times higher rate of revision among mobile-bearing implants compared with fixed-bearing implants at 3 years after TAA. Reoperations, including first and subsequent procedures, tended to be less common and the causes and types of reoperations less extensive among fixed-bearing implants.

LEVEL OF EVIDENCE

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

Total Ankle Arthroplasty Survivorship: A Meta-analysis

The gold standard for management of end-stage ankle arthritis was previously ankle arthrodesis; however, improvements in total ankle replacements are making this a more viable treatment option. The primary aim of this meta-analysis was to evaluate the survivorship of total ankle replacement implants currently in use. An extensive search strategy initially captured 20,842 citations that were evaluated for relevance. Abstract screening produced 97 articles to be read in entirety, of which 10 articles studying 1963 implants met all prospective inclusion criteria for analysis. Overall survivorship of all implants was 93.0% (95% confidence interval, 85.2-96.9) using a random effect model. There was significant heterogeneity between the studies (Q = 131.504). Meta-regression identified an inverse relationship between survivorship and study follow-up duration (p < .0001). Furthermore, age (p = .36) and implant type (fixed-bearing [95.6%, 95% confidence interval, 85.9-98.7] versus mobile-bearing ]89.4%, 95% confidence interval, 79.6%-94.8%]) did not have a statistically significant impact on survivorship, p = .213. However, patients with higher preoperative functional scores had improved survivorship (p = .001). Complications were inconsistently reported with varied definitions. In order of reported frequency, complications were classified into technical error (28.15%), subsidence (16.89%), implant failure (13.28%), aseptic loosening (6.3%), intraoperative fracture (5.67%), wound problems (4.3%), deep infection (1%), and postoperative fracture (0.0001%). Overall study quality was low, with only 10% being prospective and 90% from nonregistry data. The results from this meta-analysis revealed a promising overall survivorship of current implants in use for total ankle replacement; however higher quality studies with standardized outcomes measures are needed.

Radiographic and Clinical Outcomes of the Salto Talaris Total Ankle Arthroplasty

BACKGROUND

The Salto Talaris is a fixed-bearing implant first approved in the US in 2006. While early surgical outcomes have been promising, mid- to long-term survivorship data are limited. The aim of this study was to present the survivorship and causes of failure of the Salto Talaris implant, with functional and radiographic outcomes.

METHODS

Eighty-seven prospectively followed patients who underwent total ankle arthroplasty with the Salto Talaris between 2007 and 2015 at our institution were retrospectively identified. Of these, 82 patients (85 ankles) had a minimum follow-up of 5 (mean, 7.1; range, 5-12) years. The mean age was 63.5 (range, 42-82) years and the mean body mass index was 28.1 (range, 17.9-41.2) kg/m². Survivorship was determined by incidence of revision, defined as removal/exchange of a metal component. Preoperative, immediate, and minimum 5-year postoperative AP and lateral weightbearing radiographs were reviewed; tibiotalar alignment (TTA) and the medial distal tibial angle (MDTA) were measured to assess coronal talar and tibial alignment, respectively. The sagittal tibial angle (STA) was measured; the talar inclination angle (TIA) was measured to evaluate for radiographic subsidence of the implant, defined as a change in TIA of 5 degrees or more from the immediately to the latest postoperative lateral radiograph. The locations of periprosthetic cysts were documented. Preoperative and minimum 5-year postoperative Foot and Ankle Outcome Score (FAOS) subscales were compared.

RESULTS

Survivorship was 97.6% with 2 revisions. One patient underwent tibial and talar component revision for varus malalignment of the ankle; another underwent talar component revision for aseptic loosening and subsidence. The rate of other reoperations was 21.2% (n = 18), with the main reoperation being exostectomy with debridement for ankle impingement (n = 12). At final follow-up, the average TTA improved 4.4 (± 3.8) degrees, the average MDTA improved 3.4 (± 2.6) degrees, and the average STA improved 5.3 (± 4.5) degrees. Periprosthetic cysts were observed in 18 patients, and there was no radiographic subsidence. All FAOS subscales demonstrated significant improvement at final follow-up.

CONCLUSIONS

We found the Salto Talaris implant to be durable, consistent with previous studies of shorter follow-up lengths. We observed significant improvement in radiographic alignment as well as patient-reported clinical outcomes at a minimum 5-year follow-up.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Prospective Randomized Trial Comparing Mobile-Bearing and Fixed-Bearing Total Ankle Replacement

BACKGROUND

Outcomes of total ankle replacement for the treatment of end-stage ankle arthritis continue to improve. Debate continues whether a mobile-bearing total ankle replacement (MB-TAR) or a fixed-bearing total ankle replacement (FB-TAR) is superior, with successful outcomes reported long term for MB-TAR and at intermediate- to long-term follow-up for newer generation FB-TAR. Although comparisons between the 2 total ankle designs have been reported, to our knowledge, no investigation has compared the 2 designs with a high level of evidence. This prospective, randomized controlled trial conducted at a single institution compares patient satisfaction, functional outcomes, and radiographic results of the mobile-bearing STAR and the fixed-bearing Salto-Talaris in the treatment of end-stage ankle arthritis.

METHODS

Between November 2011 and November 2014, adult patients with end-stage ankle osteoarthritis failing nonoperative treatment were introduced to the study. With informed consent, 100 patients (31 male and 69 female, average age 65 years, range 35-85 years) were enrolled; a demographic comparison between the 2 cohorts was similar. Exclusion criteria included inflammatory arthropathy, neuropathy, weight exceeding 250 pounds, radiographic coronal plane deformity greater than 15 degrees, or extensive talar dome wear pattern ("flat-top talus"). Prospective patient-reported outcomes, physical examination, and standardized weightbearing ankle radiographs were obtained preoperatively, at 6 and 12 months postoperatively, and then at yearly intervals. Data collection included visual analog pain score, Short Form 36, Foot and Ankle Disability Index, Short Musculoskeletal Functional Assessment, and American Orthopaedic Foot & Ankle Society ankle-hindfoot score. Surgeries were performed by a nondesign team of orthopedic foot and ankle specialists with total ankle replacement expertise. Statistical analysis was performed by a qualified statistician. At average follow-up of 4.5 years (range, 2-6 years) complete clinical data and radiographs were available for 84 patients; 7 had incomplete data, 1 had died, 4 were withdrawn after enrolling but prior to surgery, and 4 were lost to follow-up.

RESULTS

In all outcome measures, the entire cohort demonstrated statistically significant improvements from preoperative evaluation to most recent follow-up with no statistically significant difference between the 2 groups. Radiographically, tibial lucency/cyst formation was 26.8% and 20.9% for MB-TAR and FB-TAR, respectively. Tibial settling/subsidence occurred in 7.3% of MB-TAR. Talar lucency/cyst formation occurred in 24.3% and 2.0% of MB-TAR and FB-TAR, respectively. Talar subsidence was observed in 21.9% and 2.0% of MB-TAR and FH-TAR, respectively. Reoperations were performed in 8 MB-TARs and 3 FH-TARs, with the majority of procedures being to relieve impingement or treat cysts and not to revise or remove metal implants.

CONCLUSION

With a high level of evidence, our study found that patient-reported and clinical outcomes were favorable for both designs and that there was no significant difference in clinical improvement between the 2 implants. The incidence of lucency/cyst formation was similar for MB-TAR and FH-TAR for the tibial component, but the MB-TAR had greater talar lucency/cyst formation and tibial and talar subsidence. As has been suggested in previous studies, clinical outcomes do not necessarily correlate with radiographic findings. Reoperations were more common for MB-TAR and, in most cases, were to relieve impingement or treat cysts rather than revise or remove metal implants.

LEVEL OF EVIDENCE

Level I, prospective randomized study.

Outcomes Following Total Ankle Arthroplasty: A Review of the Registry Data and Current Literature

End-stage ankle arthritis has a significant effect on function and quality of life. Total ankle arthroplasty continues to emerge as a safe and effective treatment of ankle arthritis. Ankle arthroplasty preserves motion at the ankle joint, while still achieving the primary goal of pain relief. With encouraging outcomes and improved implant longevity, there has been significant improvement on the results of first-generation implants. Further high-quality studies are required to clarify outcomes post ankle arthroplasty. This article reviews the latest data from national registries and the wider literature to evaluate the current status with outcomes of modern total ankle replacements.

The Salto total ankle arthroplasty - Clinical and radiological outcomes at five years

BACKGROUND

Modern designs of total ankle arthroplasty (TAA) have the potential to treat symptomatic ankle OA without adversely affecting ankle biomechanics. We present the mid-term results of a modern, mobile-bearing TAA design.

METHODS

TAA was performed in 50 consecutive patients (55 ankles) in an independent, prospective, single-centre series. Implant survival, patient-reported outcome measures (PROMs) and radiographic outcomes are presented at a mean of five years (range 2-10.5years).

RESULTS

A total of three patients (four ankles) died and two (two ankles) were lost to follow-up. Three TAAs were revised for aseptic loosening (in two cases) or infection. Two further patients underwent reoperations, one for arthroscopic debridement of anterolateral synovitis and one for grafting of an asymptomatic tibial cyst. With all-cause revision as an endpoint, implant survival was 93.3% at five to ten years (95% CI 80.5%-97.8%). If reoperations are included this falls to 90.2% (95% CI 75.6%-96.3%) at five years. No other patient demonstrated radiographic evidence of loosening or subsidence. PROMs and satisfaction were excellent at latest follow-up.

CONCLUSION

At five years, the outcomes for this design of TAA in this series were excellent, and were similar to those of previously published series from the designer centre.

Comparison of 25 ankle arthrodeses and 25 replacements at 67 months' follow-up

INTRODUCTION

In the treatment of osteoarthritis of the ankle, controversy persists between advocates of arthrodesis and of joint replacement.

HYPOTHESIS

Results of total ankle replacement (TAR) are equivalent to those of ankle arthrodesis (AA).

MATERIAL AND METHODS

A single-center continuous retrospective series included 50 patients (25 TAR, 25 AA) operated on by a single surgeon. TAR used the standard Salto^® mobile-bearing prosthesis, and arthrodesis used screws or plates. Results were assessed clinically on AOFAS score, visual analog scale (VAS) and satisfaction questionnaire, and radiologically on X-ray and CT. Survivorship in the 2 procedures was estimated on the Kaplan Meier method.

RESULTS

At a mean 67 months' follow-up (range, 40-105 months), mean AOFAS and VAS scores were significantly better in the AA group (74.1 and 1.9, respectively) than in the TAR group (67 and 3.5, respectively) (p<0.001). In the AA group, 80% of patients were satisfied or very satisfied, compared to 64% after TAR. Five-year survival without revision for non-union (AA) or implant removal (TAR) was similar between groups: AA, 96%; TAR, 90% (p=0.72). In contrast, survival with no revision procedures was significantly better with AA (96%) than TAR (75%) (p=0.03).

DISCUSSION

At 5 years, surgical revision rates were significantly greater than after standard Salto^® mobile-bearing TAR than for arthrodesis, notably due to onset of cysts; we therefore decided to abandon this implant.

LEVEL OF EVIDENCE

IV, comparative retrospective study.

Design Rationale for Total Ankle Arthroplasty Systems: An Update

The design of total ankle arthroplasty systems is evolving as a result of findings from longer-term studies. Our understanding of modes of failure has increased, and surgical techniques have become more refined. Currently, five total ankle arthroplasty systems are used in the United States. The landscape has changed considerably in the decade since the latest article reviewing total ankle design was published. Some implants with acceptable intermediate results had much poorer outcomes at 7- to 10-year follow-up. As more research showing mid- to long-term outcomes is published, the design rationale and current outcomes data for each of these implants must be considered.

Short-term Clinical and Radiographic Results of the Salto Mobile Total Ankle Prosthesis

BACKGROUND

The mobile-bearing Salto total ankle prosthesis has been reported to have promising outcomes. However, clinical reports on this prosthesis are few, and most have been published by the inventors and disclosed consultants.

METHODS

We retrospectively reviewed 59 patients who received Salto prosthesis unilaterally. The average follow-up was 35.9 (range, 6-56) months. Clinical and radiologic results were evaluated. Clinical results were evaluated according to visual analog scale (VAS), American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, Ankle Osteoarthritis Scale (AOS) pain and disability score, and ankle range of motion (ROM) in dorsiflexion/plantarflexion. In the radiographic evaluation, we measured the tibial angle (TA), talar angle (TAL), tibial slope, and talocalcaneal angle (TCA) on weightbearing radiographs.

RESULTS

By the last follow-up, 7 of 59 patients (11.9%) had undergone reoperation, and 3 of 59 implants (5.1%) had been removed. The prosthesis survival was 94.9% (95% CI, 89.1%-100%). With any reoperation as the endpoint of follow-up, the clinical success rate was 88.1% (95% CI, 79.4%-96.9%). The mean postoperative visual analog scale score, AOFAS ankle-hindfoot score, and Ankle Osteoarthritis Scale pain and disability score improved significantly ( P < .001). The ankle range of motion also improved from preoperative 33.4 ± 16.6 to 40.3 ± 15.5 postoperatively ( P < .001); however, there was no statistically significant change in plantarflexion ( P = .243). Radiolucent areas and osteolysis were found in 28 (47.5%) and 27 (45.8%) patients, respectively. Heterotopic ossification was observed in 13 patients (22.0%).

CONCLUSIONS

In this series, early clinical and radiographic outcomes of this prosthesis were promising. We believe the early radiolucent lines were probably due to the gap at the implant and bone interface, and they disappeared at the time of osseous integration. However, longer follow-up is necessary to determine the long-term durability and survivorship of this implant, particularly given the high incidence of postoperative osteolysis.

LEVEL OF EVIDENCE

Level IV, case series.

Fixed and mobile-bearing total ankle prostheses: Effect on tibial bone strain

BACKGROUND

Total ankle replacement is associated to a high revision rate. To improve implant survival, the potential advantage of prostheses with fixed bearing compared to mobile bearing is unclear. The objective of this study was to test the hypothesis that fixed and mobile bearing prostheses are associated with different biomechanical quantities typically associated to implant failure.

METHODS

With a validated finite element model, we compared three cases: a prosthesis with a fixed bearing, a prosthesis with a mobile bearing in a centered position, and a prosthesis with mobile bearing in an eccentric position. Both prostheses were obtained from the same manufacturer. They were tested on seven tibias with maximum axial compression force during walking. We tested the hypothesis that there was a difference of bone strain, bone-implant interfacial stress, and bone support between the three cases. We also evaluated, for the three cases, the correlations between bone support, bone strain and bone-implant interfacial stress.

FINDINGS

There were no statistically significant differences between the three cases. Overall, bone support was mainly trabecular, and less effective in the posterior side. Bone strain and bone-implant interfacial stress were strongly correlated to bone support.

INTERPRETATIONS

Even if slight differences are observed between fixed and mobile bearing, it is not enough to put forward the superiority of one of these implants regarding their reaction to axial compression. When associated to the published clinical results, our study provides no argument to warn surgeons against the use of two-components fixed bearing implants.

Salto Talaris Total Ankle Arthroplasty: Clinical Results at a Mean of 5.2 Years in 78 Patients Treated by a Single Surgeon

BACKGROUND

In recent years, the number of total ankle arthroplasty procedures performed has increased dramatically. We sought to report the clinical results of the largest cohort of patients treated with a modern fixed-bearing total ankle arthroplasty by a single surgeon.

METHODS

We retrospectively reviewed the charts of 78 consecutive patients (81 ankles) who underwent total ankle arthroplasty with a minimum clinical follow-up of 2 years. Sixty-three patients completed standardized questionnaires including the Foot and Ankle Disability Index (FADI), the Short Musculoskeletal Function Assessment (SMFA), the Short Form (SF)-36v2, and a visual analog scale (VAS) for pain. In addition, each patient underwent serial range-of-motion examination and radiographic implant evaluation at each follow-up appointment.

RESULTS

Implant survival was 97.5% at a mean follow-up time of 5.2 years. There was 1 revision of a tibial component and 1 revision of a talar component. Thirty-six patients underwent a concurrent procedure at the time of the index surgery, with the most common being removal of previous hardware. Seventeen patients underwent additional procedures following the index surgery, with the most common being gutter debridement. Total range of motion averaged 35.5° preoperatively and 39.9° postoperatively (p = 0.02). Fifty-seven ankles (70%) had >2 years of radiographic follow-up, and 25 ankles (31%) displayed evidence of lucency around a metallic component at the final radiographic follow-up. Outcome scores at a mean of 5.2 years revealed promising results for the cohort, with a mean VAS pain score of 17.7 and a mean FADI score of 79.1.

CONCLUSIONS

Modern fixed-bearing total ankle arthroplasty had excellent implant survival, improved plantar flexion and total range of motion, and had good-to-excellent functional outcome at a mean follow-up of 5.2 years.

LEVEL OF EVIDENCE

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

The Salto Talaris XT Revision Ankle Prosthesis

The Salto Talaris XT Revision Ankle Prosthesis is an anatomically designed fixed-bearing prosthesis available in the United States based on the design of previous Salto systems. The Salto Talaris XT Revision Ankle Prosthesis design optimizes surface area, cortical contact, and ultrahigh-molecular-weight polyethylene conformity. Two tibial component designs, both with the same base plate dimensions, are available, the standard conical fixation plug affixed to a short keel and a long-stemmed version. The author presents an overview of the Salto Talaris XT Revision Ankle Prosthesis surgical technique and pearls for successful application.