Fixed-bearing Total Ankle Arthroplasty Research Articles

3D kinematics of tibiotalar motion in patients with mobile bearing and fixed bearing total ankle arthroplasty: In vivo videofluoroscopic feasibility study

BackgroundAs total ankle arthroplasty (TAA) is an increasingly common surgical intervention for patients with end-stage ankle arthritis, there is a need to better understand the dynamic performance of prosthetic implants during activities of daily living. Our purpose was to quantify and compare relative tibiotalar motion during gait in persons with a fixed-bearing (FB) and mobile-bearing (MB) total ankle arthroplasty. We hypothesized a FB prosthesis would have lower tibiotalar range of motion (ROM). MethodsPatients at least 12 months postoperative with either a FB (n=5) or MB (n=3) total ankle arthroplasty were tested. We used high-speed biplanar videoradiography to quantify tibiotalar kinematics during self-selected gait. Angular and linear ROM in three axes were compared between the groups. ResultsROM for dorsiflexion-plantarflexion, internal-external rotation, and inversion-eversion angles in FB subjects averaged 7.47±4.05°, 7.39±3.63°, and 4.51±2.13°, respectively. ROM in MB subjects averaged 6.74±2.04°, 6.28±4.51°, and 5.68±2.81°, respectively. Linear ROM along anteroposterior, mediolateral, and superior-inferior axes in FB subjects averaged 1.47±2.07 mm, 1.13±1.49 mm, and 0.28±0.30 mm, respectively. Linear ROM in MB subjects averaged 0.68±1.44 mm, 0.60±1.41 mm, and 0.20±0.13 mm, respectively. We found no significant difference between the two groups for any of these ROM parameters (p>0.05). ConclusionTotal ankle arthroplasty using either FB or MB design appears to confer similar ankle motion during the gait cycle in this biplanar fluoroscopic model. Level of evidenceLevel IV, case series.

Improved Survival Rates with Fixed Bearing Total Ankle Arthroplasty

Introduction/Purpose: With increasing total ankle arthroplasty (TAA) being performed and a plethora of new survivorship data available, an updated literature review is needed to better understand the impact of different types of implants on the outcomes of TAA. The purpose of this study is to compare the outcomes of fixed vs mobile bearing TAAs in the literature. Methods: A comprehensive search of MEDLINE for all articles published between 2004 and 2023 was conducted with a minimum two-year mean follow-up. Two reviewers evaluated each study to determine whether it was eligible for inclusion and abstracted the data of interest. Meta-analytic pooling of group results across studies was performed, examining implant survival and component failure. Seventy-three implant groups met inclusion criteria (only 3rd and 4th generation implants), composed of STAR (20), Salto (mobile bearing) (10), Salto Talaris (11), Hintegra (8), Zimmer (6), INBONE II (6), INBONE I (4), Infinity (4), Cadence (4). 41 groups (56.2%) were implanted with mobile bearing devices, and 32 (43.8%) with fixed bearing implants. In total, 6498 subjects were included, with a mean age of 61.77 years and a mean BMI of 28.5 kg/m2. At a mean follow-up of 62.2 months, the overall reoperation rate was 21.13% and the metal component revision rate was 10.16%. Results: The mean follow-up of mobile bearing TAA studies (N =41) was 77.8 (range 24-188.4) months, and that of fixed bearing studies (N =32) was 45.3 (range 24-85.2) months. Multivariate analysis of bearing type, controlling for follow-up duration, found fixed bearing implants had statistically significantly higher metal component survival rates (fixed=96.1%, mobile=87.9%, p=.001); however, there were no statistically significant differences in rates of reoperation (fixed=17.0%, mobile=24.8%, p=.768). When examining specifically tibial and talar component failure rates, there was no statistically significant difference between bearing type (fixed tibial=1.46%, mobile tibial=2.95%, p=.472) (fixed talar=2.19%, mobile talar=2.79%, p=.966). Overall implant survival rates at one, two, five, and ten years were 96.4%, 96.0%, 92.7%, and 79.4%, respectively, and did not differ by bearing type (Table 1). Conclusion: Implant survival was statistically significantly better for 3rd and 4th generation fixed bearing TAAs as compared to mobile bearing TAAs, controlling for length of follow-up. There was no statistically significant difference in total reoperation rate. This suggests that fixed bearing implants may offer improved implant survival compared to mobile bearing implants, though further research is needed to confirm these findings.

Discrepancies Between Intraoperative and Postoperative Ankle Motion Measured for Anterior-Approach Total Ankle Arthroplasty.

Although intraoperative ankle motion serves as a foundational reference for anticipated motion after surgery and guides the addition of procedures to enhance ankle motion in total ankle arthroplasty (TAA), the relationship between intraoperative and postoperative ankle motion remains unclear. This study aimed to investigate the discrepancy between intraoperative and postoperative ankle range of motion (ROM) following TAAs using the anterior-approach, fixed-bearing systems. This study retrospectively reviewed 67 patients (67 ankles) who underwent primary TAA at a single institution. Three different types of anterior-approach, fixed-bearing TAA systems were included. Intraoperative fluoroscopy was used to document the maximal dorsiflexion and plantar flexion at the end of the case. Standardized weightbearing maximum dorsiflexion and plantar flexion sagittal radiographs were obtained pre- and postoperatively, following a previously described method. The motion between 3 different time points (preoperative, intraoperative, and postoperative [mean 11.4 months]) was compared using pairwise t tests, and their differences were quantified. The mean total tibiotalar ROM was 38.1 degrees (SD 7.8) intraoperatively, and the postoperative total tibiotalar ROM was 24.2 degrees (SD 9.7) (P < .001), indicating that a mean of 65.3% (SD 26.7) of the intraoperative motion was maintained postoperatively. Intraoperative dorsiflexion (mean 11.6 [SD 4.5] degrees) showed no evidence of difference from postoperative dorsiflexion (mean 11.4 [SD 5.8] degrees, P > .99), indicating that a median of 95.6% (interquartile range: 66.2-112) of the intraoperative maximum dorsiflexion was maintained postoperatively. However, there was a significant difference between intraoperative plantarflexion (mean 26.4 [SD 6.3]) and postoperative plantarflexion (12.8 [SD 6.9] degrees, P < .001), indicating a mean 50.6% (SD 29.6) of intraoperative motion maintained in the postoperative assessment. There was an improvement of 2.5 degrees in the total tibiotalar ROM following TAA with statistical significance (P < .043). This study revealed a significant difference between intraoperative ankle ROM and ankle ROM approximately 1 year after anterior-approach, fixed-bearing TAA, mainly due to plantarflexion motion restriction. Minimal difference in dorsiflexion suggests the importance of achieving the desired postoperative dorsiflexion motion during the surgery using the best possible adjunct procedures. Level IV, case series.

Salto Talaris Fixed-Bearing Total Ankle Arthroplasty: Long-Term Results at a Mean of 10.7 Years.

Total ankle arthroplasty (TAA) has become increasingly popular in the treatment for end-stage ankle arthritis in recent decades. However, there is limited evidence regarding the long-term clinical outcomes and complication rates of modern TAA implants. This study presents a follow-up on a previous cohort involving 78 patients (81 ankles) who underwent Salto Talaris fixed-bearing TAA to treat end-stage arthritis, with a mean postoperative follow-up of 5.2 years. The aim of this follow-up study was to assess the radiographic (33 patients, 35 ankles) and clinical (48 patients, 50 ankles) results from the original cohort at a mean of 10.7 years (range, 7.8-14 years). At a mean of 10.7 years, the Kaplan-Meier estimated survivorship was 84.2% (95% CI, 71.9%-98.6%). For the patients reviewed, we did not find any change in patient-reported outcomes between an average 5- and 11-year follow-up. Measured total range of motion and plantarflexion did not change between 1 and 11 years, but dorsiflexion was measured as decreasing by an average of 4 degrees (P < .02). In this longer-term follow-up of a limited cohort, we found that Salto Talaris fixed-bearing TAA demonstrated good long-term survival with relatively low rates of revision or other complications. Patient-reported outcome and range of motion measures revealed good stability. Level III, therapeutic.

Two-Year Survivorship and Patient-Reported Outcomes of a Prospectively Enrolled Cohort of INFINITY Total Ankle Arthroplasties.

The INFINITY total ankle implant is a widely and successfully used option for total ankle arthroplasty. The purpose of this study is to assess the 2-year survivorship, complication rates, patient-reported outcomes, and radiologic findings of prospectively enrolled patients undergoing a fixed-bearing total ankle arthroplasty (TAA). This study sought to determine if factors such as traditional vs patient-specific instrumentation, preoperative degree of arthritis, deformity, or etiology of arthritis impact surgical or clinical outcomes. A total of 143 prospectively enrolled patients (148 ankles) underwent TAA with a fixed-bearing total ankle implant between 2017 and 2019 at 9 different institutions by 9 different surgeons. A total of 116 completed 2-year follow-up. Patients were stratified by instrumentation used, degree of preoperative deformity, the Canadian Orthopaedic Foot and Ankle Society (COFAS) grading system, and etiology of arthritis. Outcomes used included implant survivorship and adverse events within 2 years of surgery. Additionally, patient-reported outcomes and radiographs were collected at 6-month, 1-year, and 2-year postoperatively. PROMs used included Ankle Osteoarthritis Score (AOS), Patient-Reported Outcomes Measurement Information System (PROMIS) global health score, the Foot and Ankle Outcome Score (FAOS), and patient satisfaction (rated from excellent to poor). Implant survivorship at 2 years was 97.79%. There were 17 reoperations (11.5%), with 4 of the implants requiring revision (2.7%). Significant improvements in all PROMs were observed among all subgroups at all postoperative time points without significant variation between subgroups. Patients classified as COFAS type 2 arthritis preoperatively demonstrated significantly more improvement in FAOS Total Symptom Score at the 1- and 2-year measurements than COFAS type 3 patients at both time points. Total ankle arthroplasty with a fixed-bearing implant system is a safe and reliable treatment option for patients with end-stage arthritis regardless of degree of deformity or COFAS grading. Level II, prospective cohort study.

Improved Survival Rates with Fixed Bearing Total Ankle Arthroplasty

Category: Ankle Arthritis Introduction/Purpose: With increasing numbers of total ankle arthroplasty (TAA) procedures being performed and a plethora of new survivorship data available, an updated literature review is needed to better understand the impact of different types of implants on outcomes of TAA. The purpose of this study is to compare the outcomes of fixed vs mobile bearing TAAs in the literature. Methods: A comprehensive search of MEDLINE for all articles published between 2004 and 2021 was conducted with a minimum two-year mean follow-up. Two reviewers evaluated each study to determine whether it was eligible for inclusion and abstracted the data of interest. Meta-analytic pooling of group results across studies was performed, examining implant survival and component failure. Seventy-three implant groups met inclusion criteria (only 3rd and 4th generation implants), composed of STAR (20), Salto (mobile bearing) (10), Salto Talaris (11 ), Hintegra (8), Zimmer (6), INBONE II (6), INBONE I (4), Infinity (4), Cadence (4). 41 groups (56.2%) were implanted with mobile bearing devices and 32 (43.8%) with fixed bearing implants. In total, 6498 subjects were included with a mean age of 61.77 years and mean BMI of 28.5 kg/m2. At mean follow-up of 62.2 months, the overall reoperation rate was 21.13% and metal component revision rate was 10.16%. Results: The mean follow-up of mobile bearing TAA studies (N=41) was 77.8 (range 24-188.4) months and fixed bearing studies (N=32) was 45.3 (range 24-85.2) months. Multivariate analysis of bearing type, controlling for follow-up duration, found fixed bearing implants had statistically significantly higher metal component survival rates (fixed=96.1%, mobile=87.9%, p=.001) ; however, there were no statistically significant differences in rates of reoperation (fixed=17.0%, mobile=24.8%, p=.768). When examining specifically tibial and talar component failure rates, there was no statistically significant difference between bearing type (fixed tibial=1.46%, mobile tibial=2.95%, p=.472) (fixed talar=2.19%, mobile talar=2.79%, p=.966). Overall implant survival rate at one, two, five, and ten years was 96.4%, 96.0%, 92.7%, and 79.4%, respectively, and did not differ by bearing type (Table 1). Conclusion: Implant survival was statistically significantly better for 3rd and 4th generation fixed bearing TAAs as compared to mobile bearing TAAs, controlling for length of follow-up. There was no statistically significant difference in total reoperation rate. This suggests that fixed bearing implants may offer improved implant survival compared to mobile bearing implants, though further research is needed to confirm these findings.

Early-to-Intermediate Clinical and Radiographic Outcomes of the Vantage Total Ankle Arthroplasty

Category: Ankle Arthritis Introduction/Purpose: The Vantage total ankle arthroplasty (TAA) features a design based on careful study of arthritic ankles and current ankle biomechanics, with theoretical advantages of a vertically-oriented tibial fixation and a fully congruent talar dome bone-implant interface. In this design-team, single-institution investigation, we report early-to-intermediate term clinical and radiographic outcomes, implant survivorship, and complications of the Vantage TAA. Methods: We retrospectively reviewed prospectively collected data for 278 consecutive patients undergoing Vantage fixed-bearing TAA. Ankles with coronal plane deformity &gt; 25 degrees and suspected poor bone quality were prospectively excluded. Prospectively collected data includes: PROMIS, SF-36, SMFA, VAS and AOFAS hindfoot-ankle scores. Using previously published and commonly accepted evaluation methods, independent radiographic analysis, performed by a non-design surgeon investigator, included pre-operative, 1-year, and most recent follow-up assessments of 2-plane alignment, component position, and the bone- implant interface. A non-design surgeon investigator with dedicated training in statistics performed the statistical analysis using descriptive statistics to report PROM and radiographic measures and Kaplan-Meier survivorship analysis. Results: Mean patient age was 64.8yrs (range:33-86), 44.2% were female, and mean follow-up was 3.1yrs (2.0-5.5). Mean preoperative and postoperative PROMs were as following: PROMIS-Depression 50.3+/-4.2 and 45.6+/-9.8, PROMIS-Physical Function 39.0+/-3.4 and 45.0+/-7.8, SF-36 total score 55.8+/-15.3 and 73.2+/-20.0, SMFA-Function 29.0+/-13.5 and 15.9+/-5.4, VAS 15.8+/-24.8 and 3.1+/-10.1, and AOFAS hindfoot-ankle 46.3+/-16.5 and 81.1+/-16.3 (Table 1). Radiographic lucency at the bone- implant interface was noted in 33 (18.5%) TAAs at final follow-up; 20 (11.2%) were progressive. Lucency was almost exclusive to the tibial component. Implant survivorship was 99.6% [98.9-100.0] at 1-year and 93.3% [88.7-98.2] at the 5-year mark (Table 2, Figure 1). We identified suboptimal bone preparation, initial component alignment and/or component position in all 11 implant failures (Table 3). Conclusion: At early-to-intermediate followup, we observed favorable clinical outcomes, radiographic results and implant survivorship for the fixed-bearing Vantage TAA, especially with optimal bone preparation and component position. Tibial component lucency remains a concern and warrants further investigation. Suboptimal bone preparation, initial component alignment and/or component position was observed in all implant failures.

Early Revisions, Reoperation, and Survivorship of the Exactech Vantage Fixed-Bearing Total Ankle Arthroplasty Implant

Category: Ankle Arthritis; Ankle Introduction/Purpose: In the last decade, there has been a rapid increase in the number of total ankle arthroplasties (TAA) performed annually. In addition, multiple novel TAA implants have been introduced onto the market. The Exactech Vantage TAA is a fixed-bearing implant that has been in use since 2016. The tibial component is low-profile with vertically oriented pegs and a cage, while the talus is curved with an anterior flange to prevent subsidence. This study sought to describe the early experience with the Vantage TAA, including reoperation, revision, and radiographic outcomes. Methods: This is a single-center retrospective review of patients who underwent primary TAA using the Vantage Total Ankle (Exactech, Gainesville, FL). Concomitant procedures at the time of index surgery were recorded. Five surgeons contributed patients. Demographics, clinical and operative data, postoperative complications, reoperations, and revisions were collected. Revisions and reoperations were classified by standardized criteria. Radiographs were reviewed by a fellowship-trained foot and ankle surgeon to assess for alignment and peri-implant complications. There were 190 patients included in the study who were all minimum 2 years post-TAR, with mean clinical follow-up of 1.8 years (range: 1-48 months), and mean age 63.3 +- 9.4 years. Ankle arthritis etiologies were 45% post-traumatic (fracture history), 33% instability, 12% primary osteoarthritis, 5% flatfoot, 2% inflammatory arthritis, and 4% other. Thirteen patients (7%) had hindfoot fusion performed previously or at the time of index surgery. Concomitant procedures are shown in Table. Results: Overall implant survivorship was 95.3%. There were 5 intraoperative complications: 4 anterolateral tibial fractures and 1 medial malleolar fracture, all treated with internal fixation at the time of surgery with no further complications. Nine patients (4.8%) underwent revision: 7/9 for tibial loosening, 1 for talar loosening, and 1 for periprosthetic joint infection. Eleven patients (5.8%) underwent reoperation: open gutter debridement (5); irrigation and debridement for superficial infection (4); and bone grafting for cysts (2). Radiographically, preoperative coronal alignment was mean 10.1°, with 87 (49%) ankles with &gt;10° deformity. Three patients had tibial component subsidence that was stable, 3 had stable radiolucency around the tibial component, and 1 had valgus failure through the ankle joint. Nineteen had asymptomatic peri-implant cysts; 16/19 were at the tibia. Conclusion: Short-term results of the Vantage TAA implant demonstrate survivorship of 95.3% at 2 years, which is comparable to similar studies of low-profile, non-stemmed implants. Asymptomatic radiographic complications were primarily cystic changes at the tibial component. Revisions occurred primarily due to loosening of the tibial component. Additional follow-up and multi- institutional support are warranted to further quantify survivorship and risk factors.

After Total Ankle Arthroplasty, When Does Bone Perfusion and Metabolic Activity at the Bone-Implant Interface Normalize? A PET/CT Study

Category: Ankle Arthritis Introduction/Purpose: Radionuclide bone scintigraphy in combination with computed tomography (CT) has been used to evaluate painful total hip and knee arthroplasties, and has also been used in the evaluation of the painful total ankle arthroplasty (TAA). Increased tracer uptake around implants may indicate loosening, but uptake characteristics of bone-seeking radiopharmaceuticals in asymptomatic total ankle patients have not been clarified. While findings of increased metabolic activity may prompt surgical intervention, there has been no work performed to define when postoperatively periprosthetic activity normalizes, if at all. In this study, we plan to establish normative data on 18F sodium fluoride (18F-NaF) positron emission tomography/CT (PET/CT) uptake ratios around TAA implants at various time intervals after surgery in asymptomatic TAA patients. Methods: The majority of the arthroplasty literature has investigated use of SPECT/CT performed with 99mTc-labeled bisphosphonates. However, data suggest that 18F-NaF PET/CT may be superior for this indication, with more favorable pharmacokinetics and similar sensitivity to detect aseptic loosening. In the present study, asymptomatic patients who underwent TAA with a modern fixed-bearing TAA prosthesis (either the Wright Infinity Adaptis or Exactech Vantage prosthesis) for posttraumatic arthritis were eligible for inclusion. Patients with ipsilateral hindfoot fusion and with any periprosthetic lucencies or cysts were excluded. Patients were enrolled at one of four time intervals following TAA: 6, 12, 18, or 24 months. Standard uptake values were measured at the bone-implant interface for the tibial and talar components on static PET, in regions of interest defined on axial CT scan slices. Periprosthetic bone blood flow (K1) and bone turnover (flux) were assessed at each time interval in each periprosthetic region using dynamic PET. Results: Sixteen asymptomatic patients underwent PET/CT: 4 patients at 6 months postoperatively, 6 at 12 months, and 6 at 24 months. We are currently still in data collection and at this time only 2 patients at 18 months have completed the scan, therefore their data were excluded. The average age was 65 years (range, 55 to 80) and 6 patients were female (38%), with individual patient data shown in the Table. Talar K1 and flux both appeared to increase from 6 to 12 months, and decrease between 12 and 24 months, although there was no statistically significant difference between timepoints. Overall tibial K1 and flux appeared to decrease slightly from 6 to 12 months, and stayed relatively stable between 12 and 24 months, again with no significant difference between timepoints (Figure). Conclusion: There is currently no normative data to help guide interpretation of radionuclide bone scintigraphy for the painful TAA. The present study utilizing 18F-NaF PET/CT scans demonstrates that even in asymptomatic patients, periprosthetic bone blood flow and bone turnover remain elevated up to 24 months following modern fixed-bearing TAA. Not only do these values remain elevated at 24 months, but we found that there does not appear to be any significant decrease in either measurement over time from 6 to 24 months postoperatively. Our findings suggest that radionuclide bone scintigraphy should be cautiously interpreted when performed within 2 years of TAA.

Inching Closer to the End of the Debate Between Fixed Versus Mobile-Bearing Total Ankle Arthroplasty: Commentary on an article by M. Assal, MD, et al.: "Three-Year Rates of Reoperation and Revision Following Mobile Versus Fixed-Bearing Total Ankle Arthroplasty. A Cohort of 302 Patients Treated with 2 Implants of Similar Design".

Commentary The study by Assal et al. presents an interesting perspective on fixed versus mobile-bearing prostheses in total ankle arthroplasty (TAA) because the study utilizes similarly designed prostheses from the same manufacturer, with all surgical procedures performed by 1 of 2 surgeons. The Salto (integra) prosthesis was designed by French surgeons in 1997, showing good initial results with short- and mid-term follow-up studies1,2. This prosthesis has a 3-component design with a mobile-bearing spacer. The Salto Talaris (integra) was introduced to the U.S. market in 2006 and to the European market in 2012. There were minor design changes between the Salto and the Salto Talaris, mainly to accommodate a fixed bearing on the tibial component of the latter prosthesis in order to allow 510(k) approval by the Food and Drug Administration in the U.S. Over the years, there have been multiple studies discussing the short- and mid-term outcomes of either the Salto or the Salto Talaris, with prostheses showing acceptable if not excellent results3-5. The debate regarding fixed versus mobile-bearing prostheses has been ongoing for many years. The concept of a mobile-bearing prosthesis was introduced with the theoretical advantage of having better-conforming articular surfaces and lower contact stress, with the dissipation of stress over a more consistent area of the joint. Another theoretical advantage was the self-correction and positioning of the polyethylene spacer, reducing wear and stress on the spacer itself. However, the majority of studies have not confirmed these theoretical advantages and in fact have suggested that the use of a mobile-bearing prosthesis leads to a higher rate of complications in the first year postoperatively6. In a 2014 study retrospectively comparing the use of fixed versus mobile-bearing prostheses with a minimum follow-up of 2 years, Gaudot et al. reported that mobile-bearing prostheses had higher rates of radiolucent lines (40%) and cyst formation (24%) compared with fixed-bearing prostheses (12% and 3%, respectively)7. One strength of the study by Assal et al. was that it included 2 relatively large cohorts, with 131 fixed-bearing TAAs and 171 mobile-bearing TAAs. The mobile-bearing procedures were performed in the earlier half of the study period. As a result, 1 theoretical concern was regarding the surgical experience of the surgeons over time; however, the surgeons had been performing mobile-bearing TAAs since 2000, with the study period beginning in 2004, so they were adequately experienced with the procedure by the outset of the study. The authors also reported that the complication rate in the mobile-bearing group was stable throughout the study period and did not decrease with time. The most important conclusion of this study was that the rate of revision was 3 times higher among mobile-bearing compared with fixed-bearing prostheses. Most concerning was that most of the reported failures of mobile-bearing TAAs were because of cyst formation and gutter impingement due to heterotopic bone formation, with these prostheses showing higher rates of heterotopic bone formation in the medial and lateral gutters. There were several questions that went unanswered in the study by Assal et al and that should be addressed in future studies. What caused the increased rate of lysis, cysts, hypertrophic bone, and failure among mobile-bearing TAAs? One possible explanation is the smaller spacer utilized in the mobile-bearing implant, which increases the load per square inch of the polyethylene insert, contributing to greater wear. Was there a higher rate of backside wear between the polyethylene insert and the tibial baseplate among mobile-bearing TAAs? This effect could cause an excess of problematic polyethylene debris. Was there potential for edge-loading between the polyethylene spacer and the tibial component if the overall alignment was not reasonably accurate? Along with these questions, the greatest shortcoming of the study was that it was not a prospective, randomized trial, but instead was essentially a comparison of the results of 2 longitudinal studies. However, 1 strength was that the study utilized 2 prostheses with similar designs from the same manufacturer, which will be of substantial value if the trial can continue to longer-term follow-ups. The debate regarding fixed versus mobile-bearing prostheses will continue, but the study by Assal et al. provided an interesting window into the potential shortcomings of mobile-bearing TAAs. I congratulate the authors on an excellent paper.

Surgical Technique of the VANTAGE Total Ankle Arthroplasty

The VANTAGE total ankle arthroplasty is a novel anatomic mobile or fixed-bearing total ankle arthroplasty with a good and simple instrumentation giving to surgeons a safe implantation ventral approach technique. Our first cases report a successful functional outcome for patients, with or without additional surgeries, and without very early complications.

Mid-Term Prospective Clinical and Radiographic Outcomes of a Modern Fixed-Bearing Total Ankle Arthroplasty

The early outcomes of the Salto Talaris® Total Ankle Prosthesis have been promising, but information on its mid-term outcomes is still sparse. The purpose of this study was to evaluate the mid-term clinical and radiographic outcomes of this implant among a prospective cohort of patients who underwent total ankle replacement for various etiologies. Forty-six patients (50 ankles) were consecutively enrolled in the study. Our primary aim was to assess implant survivorship as determined by the removal or revision of the implant metal components or conversion to arthrodesis. Our secondary aim was to gauge patient outcomes by using commonly used outcome scores and assess ankle range of motion using goniometric and radiographic methods. We report 100% survivorship of the implant at a mean follow-up of 4.9 years. Compared with preoperative levels, all clinical outcome scores showed significant improvement at the 1-year, 2-year, and 5-year and longer follow-up. The mean clinical ROM improved from 27.7° ± 10.7° preoperatively to 40.0° ± 12.3° at the 2-year follow-up (p < .001). The mean radiographic ROM improved from 23.0° ± 10.2° preoperatively to 27.2° ± 9.1° at the 2-year follow-up (p = .007). Reoperations or secondary procedures were performed on 6 (12%) ankles, with the most common procedure being gutter debridement for impingement symptoms. The study confirms that the excellent survivorship seen with the implant in the early studies extends to mid-term follow-up as well. Patients could expect to see improvement in pain relief and activity well into 5 years after surgery and retain sufficient ankle range of motion for normal gait.

Evaluation of Total Ankle Arthroplasty Using Highly Crosslinked Ultrahigh-Molecular-Weight Polyethylene Subjected to Physiological Loading.

Highly crosslinked polyethylene (HXLPE) was developed for its superior wear properties in comparison to conventional polyethylene (CPE). Concern over fatigue resistance has prevented widespread adoption of HXLPE for use in total ankle arthroplasty (TAA). The aim of this study was to determine whether HXLPE has sufficient fatigue strength for total ankle arthroplasty under simulated physiologically relevant motion profiles and loading in the ankle. Physiologic load and motion profiles representative of walking gait were incorporated into a computational model of a semiconstrained, fixed-bearing TAA to determine the loading state with highest stresses in the HXLPE bearing. Subsequent fatigue testing to 10 million cycles (Mc) at 5600 N was performed to assess bearing strength. Peak stresses in the bearing were predicted at peak axial load and peak dorsiflexion during gait, occurring near heel off. All samples withstood 10 Mc of fatigue loading at that orientation without polyethylene bearing fracture. HXLPE had sufficient fatigue strength to withstand 10 Mc of loading at more than 5 times body weight at the point of peak stresses during simulated gait in total ankle arthroplasty. HXLPE may be mechanically strong enough to withstand the in vivo demands of the ankle. Improvements in wear afforded by HXLPE can be obtained without compromising sufficient polyethylene strength properties in total ankle arthroplasty.

In vivo kinematics of fixed-bearing total ankle arthroplasty

BackgroundA good recovery of the physiological mobility of the ankle is an indication of patients’ satisfaction after total ankle arthroplasty, which does not generally match that of other consolidated procedures such as hip and knee replacement. The aim of this study was to investigate the kinematics of the Zimmer Total Metal Total Ankle (ZTMTA) during the different exercises. MethodsFifteen patients with ZTMTA were enrolled in this study. The patients performed non-weightbearing flexion-extension, stair climbing and descending, and fluoroscopic images were taken to capture the ankle movements. A combined images/three-dimensional models method was used to perform a kinematic analysis. ResultsPlantar-dorsiflexion resulted the main plane of movement, with the largest range of motion (ROM) of 23.3 ± 9.0° during flexion-extension. Inversion–eversion and adduction–abduction resulted lower than 10° in any trials. ConclusionsIn the investigated population, the ZTMTA allowed a good recovery of the mobility, with ROMs comparable to the healthy subjects.

A Comparison of Cyst Formation and Management in Mobile-Bearing and Fixed-Bearing Total Ankle Arthroplasty

Category:Ankle ArthritisIntroduction/Purpose:The Scandinavian Total Ankle Replacement(STAR) system and Salto Talaris(ST) total ankle system are two of the more commonly studied total ankle implants. As the STAR is one of the oldest total ankle arthroplasty (TAA) implants still in use today, most studies focus on longevity and survivorship. Reported rates of cyst formation for these two prosthesis in most series vary from 11-22% but no large study has focused on surgical management of these cysts or included patient reported outcomes after surgery. In this series, we aimed to investigate rates of cyst formation between mobile(MB) and fixed-bearing(FB) TAA and examine clinical and patient reported outcomes of bone grafting or cementing of large cysts surrounding the STAR and ST implants.Methods:A prospectively collected database at a high volume total ankle replacement center was retrospectively reviewed to identify patients who underwent TAA with either the STAR or the ST total ankle system between 2007 and 2015. Cysts were identified and measured on standard weight bearing radiographs and confirmed on computed tomography(CT) when available. Visual analog scale (VAS) score, Short Form-36 (SF-36) physical and mental component scores, Short Musculoskeletal Function Assessment(SMFA), and AOFAS hindfoot scores were collected from all patients preoperatively and then at 6 months, 1 year and annually postoperatively. Patients with a minimum 2 years follow-up who underwent revision TAA secondary to catastrophic bone cysts or who were managed with either curettage and bone grafting or curettage and cementing of bone cysts surrounding the TAA prosthesis were included in the patient reported outcomes (PRO) analysisResults:Excluding 53 patients for inadequate follow-up, 232 patients (29% female, 71% male; follow-up 6.7 years) who underwent STAR-TAA and 147 patients (26.6% female, 73.5% male; follow-up 7 years) who underwent ST-TAA were identified. Cysts <20 mm diameter occurred more often in the MB TAAs, and more often in the tibia than talus (table). Cysts >10 mm were identified in 95/232 (41%) STAR and 24/147 (16%) ST ankles. In the STAR group, 24 patients underwent cyst bone grafting (13), cementing (6) or both (8) at a mean 4.8 years. In the ST group, 14 patients underwent cyst bone grafting (6), cementing (4), or both (4) at a mean of 2.7 years. PRO data improved significantly for both the STAR and ST group in all questionnaires (p<0.05 for all).Conclusion:Mobile-bearing total ankle arthroplasty in this cohort had a higher rate of cyst formation greater than 10 mm (95/232 patients, 41%) when compared to a fixed-bearing TAA (24/147, 16.3%). Only 24/95 (25%) of STAR patients and 14/24 (58%) of ST patients required surgical intervention for cyst management. Patient reported outcomes after cyst surgery improved significantly when compared to pre-cyst management surgery and did not differ between MB and FB cohorts (p=0.424). Successful surgical management of large cyst surrounding either mobile-bearing or fixed-bearing total ankle systems can be expected based on the results of this study.Mobile-Bearing TAAFixed-Bearing TAA Total patients (n) 232147 Total Patients with Cysts >10mm95(41%)24 (16%) Patients Requiring Cyst Surgery24/95 (25%)14/24 (58%) Age (years) 61.863.3 Sex Male165(71%)107(73%) Female67(29%)40(27%) Time Until Cysts Visible (years) 1.821.63 Cysts <20mm Diameter Tibia89 patients10 patients Talus51 patients4 patients Both Tibia and Talus29 patients1 patients Cysts >20mm Diameter Tibia28 patients4 patients Talus4 patients2 patients Both0 Patients2 patients Reoperation for Cyst n=24n=14 Management mean 4.8 years post-opmean 2.7 years post-op Bone Grafting136 Cementing64 Both84 SF-36 Before Cyst Surgery Physical Function23.819.9 Mental Health75.177.9 SF-36 After Cyst Surgery Physical Function68.367.6 Mental Health89.488.8 VAS Before Cyst Surgery 62.759.4 VAS After Cyst Surgery 4.13.7

Conventional Ultra-high Molecular Weight Polyethylene versus Highly Cross-linked Polyethylene from Semi-constrained, Fixed-bearing Total Ankle Arthroplasty Systems

Category: Ankle Arthritis Introduction/Purpose: The aim of this study was to compare the polyethylene wear rate, particle size, and particle shape of primary semi-constrained, fixed-bearing, bone-sparing total ankle arthroplasty using conventional ultra-high molecular weight polyethylene (CPE) versus highly cross-linked polyethylene (HXLPE) by applying a level walking input using a joint simulator. Methods: Two fixed-bearing total ankle replacement systems with different types of polyethylene liners were tested: 1.) CPE sterilized in ethylene oxide, and 2.) HXLPE sterilized with gas plasma after electron beam irradiation. Three implants for each design underwent wear testing using gravimetric analysis over 5 million simulated walking cycles. A fourth implant was used as a load soak control. Equivalent circle diameter (ECD) and equivalent shape ratio (ESR) were computed to determine particle size and particle shape, respectively. Results: The mean wear rate from 1.5-5 million cycles (MC) was 2.0±0.3mg/MC for HXLPE and 16.7±1.3mg/MC for CPE (P &lt; 0.001). The total number of particles per cycle generated for HXLPE and CPE were 0.17x106 particles/cycle and 0.53x106 particles/cycle, respectively (P &lt; 0.001). The mean ECD of HXLPE particles (0.22 ±0.11μm) was significantly smaller than the mean ECD of CPE particles (0.32±0.14μm) (P&lt;0.001). HXLPE particles were significantly more round than CPE particles (P&lt;0.001). Conclusion: HXLPE liners had a significantly lower wear rate and produced significantly fewer and rounder particles than CPE liners. The results of this study suggest that HXLPE has more favorable wear characteristics for total ankle arthroplasty.

Total Ankle Arthroplasty

Category: Ankle, Ankle Arthritis Introduction/Purpose: Reports of ankle range of motion and how it affects patient outcomes following total ankle arthroplasty (TAA) have been mixed. Furthermore, recent studies have relied on clinical exam to obtain postoperative range of motion and have lacked preoperative functional scores. The purpose of our study was to analyze how preoperative range of motion and functional scores change with time following TAA using postoperative functional scores and radiographs for range of motion calculations. Methods: A retrospective chart review was performed on 107 patients (109 ankles) that had undergone fixed-bearing implant TAA by a single surgeon between 2010 and 2015. Preoperative range of motion was gathered clinically in office by the senior author. Postoperative range of motion through the ankle joint was evaluated with dedicated weight-bearing maximum dorsiflexion and plantarflexion lateral radiographs at 3 and 6 months, 1 and 2 years. The range of motion was measured using the angle measurement tool on the picture archiving and communication system. Patients completed visual analogue scale (VAS) for pain and the Foot and Ankle Ability Measure (FAAM) questionnaire subcategorized into activities of daily (ADL) and sports subscale preoperatively and at postoperative intervals of 3 and 6 months, 1 and 2 years. The mean age was 65 years (range, 31-83 years). Mean BMI was 28.1 (range, 14.9-44.9). There were 53 males (50%). Results: The mean total arc of ankle motion preoperatively was 20.7 degrees and improved significantly to 28.3, 34.3, 33.3, and 33.3 degrees at 3 and 6 months, 1 and 2 years, respectively (P&lt;0.001) (Figure 1). Mean VAS pain and mean FAAM ADL preoperative scores improved significantly at each postoperative time point as seen in Figure 1 (P&lt;0.001). Increased ankle range of motion was correlated with lower VAS preoperatively (r=-0.38, P=0.007), and at 1 year (r=-0.36, P&lt;0.001), and 2 years (r=-0.2, P=0.033) postoperatively. Increased ankle range of motion was significantly correlated with higher FAAM-ADL at 3 months (r=0.48, P=0.012), 1 year (r=0.24, P&lt;0.034), and 2 years (r=0.37, P&lt;0.001) postoperatively. Conclusion: Patients undergoing fixed-bearing TAA had continued and sustained improvement from preoperative total arc of motion, pain, and function at each postoperative visit, up to 2 years. Ankle range of motion was noted to peak at 6 months, while pain and FAAM-ADL continued to improve up to 2 years postoperatively. Patients with greater ankle range of motion correlated with less pain and improved function at 1 and 2 years postoperatively. Though pain and function may continue to improve even as far out as 2 years postoperatively, it is not likely that range of motion will continue to increase.

Short-Term Complications, Reoperations, and Radiographic Outcomes of a New Fixed-Bearing Total Ankle Arthroplasty

With the increasing use of total ankle arthroplasty (TAA), new implants with varied configurations are being developed every year. This study aimed to assess the early complications, reoperations, and radiographic and clinical outcomes of the Infinity TAA. To date, clinical results of this novel implant have not been published. A retrospective analysis of 64 consecutive ankles that underwent a primary Infinity TAA from July 2014 to April 2016 was performed. Patients had an average follow-up of 24.5 (range, 18-39) months. Medical records were reviewed to determine the incidence of complications, reoperations, and revisions. Radiographic outcomes included preoperative and postoperative tibiotalar alignment, tibial implant positioning, the presence of periprosthetic radiolucency and cysts, and evidence of subsidence or loosening. Additionally, patient-reported outcomes were analyzed with the Foot and Ankle Outcome Score (FAOS). Survivorship of the implant was 95.3%. Fourteen ankles (21.8%) presented a total of 17 complications. A total of 12 reoperations were necessary in 11 ankles (17.1%). Revision surgery was indicated for 3 ankles (4.7%) as a result of subsidence of the implant. Tibiotalar coronal deformity was significantly improved after surgery ( P < .0001) and maintained during latest follow-up ( P = .81). Periprosthetic radiolucent lines were observed around the tibial component in 20 ankles (31%) and around the talar component in 2 ankles (3.1%). A tibial cyst was observed in 1 ankle (1.5%). Outcome scores were significantly improved for all FAOS components analyzed ( P < .0001), from 39.0 to 83.3 for pain, from 34.0 to 65.2 for symptoms, from 52.3 to 87.5 for activities of daily living, and from 15.7 to 64.2 for quality of life. Most complications observed in the study were minor and successfully treated with a single reoperation procedure or nonoperatively. Failures and radiographic abnormalities were most commonly related to the tibial implant. Further studies with longer follow-up are needed to evaluate the survivorship of the tibial implant in the long term. Level IV, retrospective case series.

Single-Surgeon Experience and Complications of a Fixed-Bearing Total Ankle Arthroplasty.

Total ankle arthroplasty (TAA) has historically resulted in inferior survivorship rates compared with total hip and knee arthroplasty, because of technical issues unique to ankle anatomy. In this study, a single-surgeon series of intra- and postoperative complications as well as resultant reoperations/revisions of the Tornier Salto Talaris, a fixed-bearing TAA prosthesis, were reviewed. Medical records from index procedure to latest follow-up of primary TAA were reviewed. Complications were categorized according to the Glazebrook classification; additional complications were documented. Concurrent procedures were recorded, and radiographs were analyzed for alignment, subsidence, and cyst formation. Time to complication onset and learning curve analyses were performed. One hundred four Salto Talaris TAA prostheses (96 patients), with an average follow-up of 46 months, were included. Thirty-five complications were identified in 32 ankles with a 34% complication rate, resulting in 11 reoperations (5 TAA revisions). Technical error (n = 12), wound healing (n = 9), and aseptic loosening (n = 4) were the most common complications, and there were no statistically significant differences in demographics or follow-up duration between cases with versus without complications. In both the cohorts with and without complications, there were moderate, negative correlations between radiographically observed keel osteopenia and lucency (ρ = -0.548, P = .00125, and ρ = -0.416, P = .000303, respectively); also, in the complication cohort, a weak, positive correlation between subsidence and lucency (ρ = 0.357, P = .0450) was found. Salto Talaris TAA survivorship and reoperation rates in our series were comparable with previous reports, using either the same or similar mobile-bearing prostheses; new information regarding complication, radiographic, and learning curve analyses was presented. Level IV, retrospective case series.

Midterm Outcomes of a Fixed-Bearing Total Ankle Arthroplasty With Deformity Analysis.

We present our results with an INBONE I (Wright Medical, Memphis, TN) prosthesis that have a minimum of 4 to 10 years of follow-up and include a preoperative deformity analysis on outcomes. A consecutive series of 149 patients, from 2007 to 2011, at a single institution were enrolled. Pain and patient-reported function were assessed preoperatively and at yearly follow-ups. We analyzed the data for complications, reoperations, and failures (defined as undergoing revision for exchange or removal of one or both metallic components for any reason). Patients were also grouped according to coronal plane tibiotalar alignment; either ≥10 degrees or <10 degrees, and these outcomes were compared. Our follow-up ranged from 48 to 113 months (average 5.9 years). There was significant improvement ( P < .05) in the visual analog scale for pain, American Orthopaedic Foot & Ankle Society hindfoot scale, Short Musculoskeletal Function Assessment, and Short Form 36-Item Health Survey scores at most recent follow-up. There were 14 implant failures with overall survivorship of 90.6% (135/149). Reasons for failure included cysts/loosening (7), talar subsidence (4), fractured component (1), impingement pain (1), and infection (1). Seventy-two patients (48.3%) with preoperative coronal plane deformity of ≥10 degrees varus or valgus were compared to 78 patients (51.7%) with <10 degrees deformity. There was no difference in patient outcome scores or revision rates between these patient groups. There was a statistically significant difference ( P = .039) in reoperation rates among patients with ≥10 degrees deformity (22.2%) compared to those without such a deformity (37.7%) Conclusion: Patients who underwent INBONE I fixed-bearing total ankle arthroplasty demonstrated significant improvement in outcomes at a mean of 5.9 years. Catastrophic talar component collapse did occur (2.7% of cases), but relatively rarely. The patients with preoperative coronal plane tibiotalar deformity had similar pain relief, function, and need for revision of implant components. Despite the presumed shortcomings of the INBONE I's design, this implant showed promising results, with or without deformity, at midterm follow-up with survivorship of 90.6%. Level III, comparative study.