Agility Total Ankle Arthroplasty Research Articles

The Agility Total Ankle Arthroplasty: A Concise Follow-up at a Minimum of 20 Years.

Between 1984 and 1994, a single surgeon performed 132 primary cementless total ankle replacements using the Agility total arthroplasty system. The purpose of this study was to report on the 20-year follow-up, which we believe is the first study with this length of follow-up. Living patients were contacted and interviewed to determine the status of their implant (revised or unrevised) and to answer a simple questionnaire concerning overall satisfaction, pain, and functional improvement, as in a previous study. Thirty-three (26.2%) patients with 33 (25%) ankles of the original series were alive at a minimum of 20 years postoperatively, with a median follow-up of 22 years. They were asked to return to the office for standing anteroposterior and lateral ankle and foot radiographs or to send these radiographs if performed elsewhere. Radiographs were evaluated for radiolucencies around the components and subsidence (talar component) or migration (tibial component) of components. Seventeen (13.5%) ankles of the 126 available for follow-up, including 5 (15.2%) ankles in living patients, had undergone revision (n = 10) or arthrodesis (n = 7) for loosening. One additional ankle was revised for infection and 1 for talar component malposition; thus, 19 (15.1%) ankles were revised. These results should provide a 20-year benchmark for newer total ankle arthroplasty designs when a similar length of follow-up becomes available. Level III, retrospective cohort study.

Midterm Outcome of the Agility Total Ankle Arthroplasty.

Ankle arthritis is a debilitating condition that causes severe functional impairment. While arthrodesis has been the gold standard of surgical treatment for this condition, significant improvements in total ankle arthroplasty have made it a viable alternative. The purpose of this study was to look at the midterm follow-up of the Agility total ankle. A retrospective review of prospectively collected data was conducted on 127 consecutive Agility total ankles implanted between 2002 and 2009. Charts were reviewed to collect patient demographics. In addition, coronal alignment, overall arc of motion, tibiotalar component motion, syndesmotic fusion, zones of osteolysis, and subsidence were determined. A Kaplan-Meier survival and linear regression analysis were used to predict implant failure. A multivariate regression analysis was used to assess whether radiographic measures were predictive of patient satisfaction. Ninety (78.2%) of 115 patients retained their primary implant, of which 105 were available for evaluation, with an average follow-up of 9.1 years. Twenty-five had their implant removed. The average score for the Foot and Ankle Ability Measure (FAAM) activities of daily living subscale was 82.4, FAAM sport subscale 55.3, postoperative visual analog scale (VAS) for pain 12.7, and Short Form-12 (SF-12) Health Survey physical component 45.8 and SF-12 mental component 56.1. Average arc of motion across the implant was 22.3 and 6.3 degrees in adjacent joints. Osteolysis most commonly occurred in zones 1 and 6. No statistical differences were found in the rate or location of subsidence. Linear regression analysis demonstrated that age at the time of surgery was predictive of failure ( P = .036). Inflammatory and atraumatic arthritis demonstrated higher likelihoods of revision. No correlation was detected between radiographic parameters and outcomes scores ( P > .05; rho >0.2). A significant reduction in mean VAS pain scores by 67.6% was maintained at an average of 8 years. Our results were improved over the nondesigner outcomes published in the current literature. Survivorship approached 80% at 9 years, with Kaplan-Meier 14-year survival calculated at 70.4%. Patients with their original implant were functioning with a high level of satisfaction based on statistically validated outcome scores, which was independent of the radiographic appearance of their implant. Age at the time of surgery and inflammatory/atraumatic arthritis were predictive of failure. Level IV, case series.

The Agility Total Ankle Arthroplasty

Category: Ankle Arthritis Introduction/Purpose: Ankle arthritis is a debilitating condition causing severe functional impairment. In contrast to degenerative arthritis of the knee and hip, ankle arthritis is typically post-traumatic and affects a younger population. While arthrodesis has been the gold standard of surgical treatment for this condition, significant improvements in total ankle arthroplasty have made it a viable alternative for select patients. As the Agility total ankle implant has the longest follow-up in the United States, the purpose of this study is to look at mid-term follow up of patients with this implant. Methods: Following IRB approval, a retrospective review of prospectively collected data was conducted on 127 consecutive Agility total ankle arthroplasties between 2001-2010 performed by one fellowship-trained orthopaedic surgeon. Patient charts were reviewed to collect demographics including age, gender, BMI, diabetes, inflammatory arthropathy, tobacco, FAAM, SF-12, and VAS pain scores. In addition, a five-view radiographic series was obtained to determine coronal alignment, overall arc of motion, tibiotalar component motion, zones of osteolysis, and subsidence. A Kaplan-Meier survival analysis was performed and a linear regression analysis was used to predict implant failure. A multivariate regression analysis was used to assess whether radiographic measures were predictive of patient satisfaction. Results: 90 of 115 still had their primary implant. 105 were available to participate (average 9.1 years follow-up). Twenty-five had their implant removed. Average FAAM-ADL score was 82.4, FAAM-sport score 55.3, post-operative VAS pain score 12.7, SF-12 physical score 45.8 and SF-12 Mental 56.1. Average motion across the implant was 22.3° and 6.3° in adjacent joints. Osteolysis occurred on average at 2.3 zones, significant at zones 1 and 6. No differences were found for rate or location of subsidence. Linear regression analysis demonstrated younger patients, inflammatory and atraumatic arthritis lead to higher likelihoods of revision. No correlation was detected between radiographic parameters of implant success and outcome scores. Significant reduction in VAS pain scores was detected at an average of 8 years (mean difference of 67.64). Conclusion: Our results are consistent with what has been described in the literature. Survivorship approaches 70.9% at an average of 8 years. Patients that have retained their original implant are functioning at a high level of satisfaction based on statistically validated patient-centered outcome scores. Interestingly, this is independent of the radiographic appearance of their implant. Advanced age at the time of surgery was predictive of failure with younger patients having a higher likelihood of requiring secondary surgery and the pre-operative diagnosis was also predictive of failure with both inflammatory arthritis and atraumatic arthritis.

Management of Failures of Total Ankle Replacement with the Agility Total Ankle Arthroplasty

Few studies have focused on treatment following failed total ankle replacement. The purpose of this study was to report the outcomes of patients undergoing revision total ankle replacement and to propose a talar component subsidence grading system that may be helpful in making decisions regarding how to revise failed total ankle replacements in the future. A retrospective review was performed of fifty-three patients who underwent revision total ankle replacement and had been followed for a minimum of two years. Patients were assessed radiographically and with outcome scores. The rates of conversion to amputation or fusion were also assessed. The mean follow-up period was 49.1 months after the revision arthroplasty. The average time from primary total ankle replacement to revision was fifty-one months. Forty-one of the fifty-three patients (77%) were available for follow-up. The revision arthroplasty had been converted to an arthrodesis in five of the forty-one patients, and two additional patients had undergone amputation. The most common indication for revision total ankle replacement was talar subsidence (63%; twenty-six of forty-one). Twenty-two patients (54%) had a subtalar arthrodesis performed at the time of the revision arthroplasty, with nineteen of those having a custom-designed long-stem talar component placed simultaneously. The mean radiographic measurements of component position did not change significantly postoperatively. The mean postoperative scores for the thirty-four patients with a retained total ankle replacement were: 4.4 of 10 possible points on a visual analog pain scale (VAS), 65 of 100 possible points on the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot scale, 93.5 of 100 possible points on the Short-Form 12 (SF-12), 137.9 of 204 possible points on the Revised Foot Function Index (FFI-R), and 64 of 180 possible points on the Ankle Osteoarthritis Scale (AOS). The mean arc of motion radiographically was 18° preoperatively and 23° postoperatively, with all improvement occurring in plantar flexion. A lesser amount of preoperative talar subsidence was a significant predictor of a good outcome based on the AOFAS hindfoot score (p < 0.03) and the AOS (p < 0.01) score. Revision arthroplasty may be considered as an alternative to arthrodesis when treating patients with a failed Agility total ankle implant.

Short-term Results of the Agility Total Ankle Arthroplasty

Purpose: Recently, there has been increasing interest in total ankle arthroplasty as an alternative to ankle arthrodesis. This study examined the short-term results of total ankle arthroplasty using an Agility prosthesis. Materials and Methods: This study reviewed the results of 11 patients who underwent total ankle arthroplasty using the Agility prosthesis between May, 2003 and May, 2004. With a postoperative follow-up period of 2 years, 10 patients (10 ankles) were available for review at the time of the follow-up. The clinical evaluation included the ankle range of motion, the personal type of preferred shoe, walking pain (VAS score) and the American Orthopaedic Foot and Ankle Society (AOFAS) ankle score. In addition, the patients were asked whether they were satisfied with the outcome and if they would choose to undergo the same procedure again. The radiologic evaluation included the loosening of the prosthesis, osteolysis and syndesmosis union. The anterior surgical approach was used. The syndesmosis area was fixed using 2 cannulated screws inserted percutaneously in 9 cases and a plate in 1 case. Results: The patients consisted of two men and eight women. The average age was 51.8 years (range 41 to 67) with an average follow-up of 30.3 (range 24 to 36) months. The mean preoperative and postoperative AOFAS ankle scores were 38.2 and 73.8, respectively, demonstrating significant improvement. The mean preoperative and final follow-up walking pain was 8.9 and 2.8, respectively. The ankle range of motion was decreased slightly at the final follow-up. Five patients required a cane to walk. Radiographic analysis showed no prosthesis failure, even though osteolysis occurred around the prosthesis in all cases. Only one case showed further progression. Union in the syndesmosis area occurred within 6 months in 5 cases and delayed union was observed in 3 cases, and nonunion was observed in 2 cases. Sensory loss in the area innervated by the deep peroneal nerve and a fracture in the lateral malleolus was encountered in one case, but this recovered with conservative treatment. Subtalar joint arthritis was noted in one case. Conclusion: Agility total ankle arthroplasty results in a favorable outcome at the short-term follow-up. However, total ankle arthroplasty is associated with radiographic complications including syndesmosis nonunion and osteolysis. Only syndesmosis nonunion was associated with the clinical results. Therefore, long-term follow-up is considered to be necessary to demonstrate osteolysis and loosening with their clinical association.

Total Ankle Arthroplasty With the Agility Prosthesis: Clinical and Radiographic Evaluation

Although ankle arthrodesis remains a standard operative procedure for disabling ankle arthritis, it has potential long-term problems. Total ankle arthroplasty offers preserved joint motion and may be a more favorable option in select patients. The purpose of this study was to report the intermediate-term clinical and radiographic results of total ankle arthroplasty using the Agility prosthesis. We retrospectively reviewed the results of total ankle arthroplasty in 41 consecutive patients (43 ankles). Evaluation included preoperative and postoperative questionnaires, physical examination, and radiographs. At the time of followup, 38 patients (40 ankles) were available for review. The most common preoperative diagnoses included posttraumatic arthritis (24 of 40 ankles, 60%) and rheumatoid arthritis (eight of 40 ankles, 20%). Average age at surgery was 63 (range 32 to 85) years. Average followup was 44.5 (range 26 to 64) months. Preoperative and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scores averaged 33.6 and 83.3, respectively, demonstrating significance (p < 0.001). Postoperative Medical Outcomes Study Short Form-36 (SF-36) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores averaged 49.5 and 56.1, respectively. Although 34 of 40 ankles demonstrated radiographic lucency or lysis, the degree of involvement varied. Migration or subsidence of components was noted in 18 ankles. Overall, 37 of 38 patients were satisfied with the outcome of their surgery and would have the same procedure under similar circumstances. Agility total ankle arthroplasty results in a favorable clinical outcome and patient satisfaction in most patients at intermediate-term followup. However, total ankle arthroplasty is associated with potential complications and the need for subsequent operative intervention. Radiographic followup commonly reveals periprosthetic lucency, lysis, and component migration or subsidence, but this does not appear to adversely affect the intermediate-term clinical outcome. The long-term consequences of such radiographic findings are of concern, and surgeons and patients choosing this procedure need to be cautious.

Joint contact characteristics in agility total ankle arthroplasty.

High component contact pressures in total joint prostheses can lead to particle wear debris and prosthesis loosening. The contact pressures in the Agility total ankle prosthesis have not been investigated. In the current study, a cadaveric model was used to evaluate contact characteristics (average contact area, contact pressure, and contact peak pressures) for the Agility total ankle system. Ten cadaveric specimens were implanted with the Agility total ankle and axially loaded to 700 N. The average contact pressure of the system was 5.6 MPa with mean peak pressures of 21.2 MPa. In a separate phase of the study, contact characteristics with applied loads for each of the six component sizes showed a significant effect of component size on contact characteristics. When physiologic ankle forces are considered for normal patient activity, peak pressures observed in the current study may exceed recommended contact pressures (10 MPa) and the compressive yield point (13-22 MPa) for polyethylene. A heavy patient with a small ankle would not be expected to have a good outcome based on the current contact pressures data, whereas a heavy patient with a larger ankle might be a better candidate for surgery.

Accurate measurement of ankle range of motion after total ankle arthroplasty.

There is no standardized method reported in the literature to measure ROM of the ankle after a total ankle arthroplasty, which limits the possibility to compare results from the various ankle designs. It seems that most of the measurements are a combination of ankle and midfoot motion, not the tibiotalar joint. A protocol was developed to accurately measure the true tibiotalar and midfoot motion before and after an ankle replacement. Lateral radiographs were taken of the ankle with the patient in a weightbearing position, and measurements were done along fixed landmarks. In this study, the tibiotalar, midfoot, and combined ROM were measured preoperative and 1 year postoperative in a standardized, reproducible fashion. The preoperative tibiotalar ROM was 18.5 degrees and combined ankle and midfoot motion 25.1 degrees. The true tibiotalar motion after an Agility total ankle arthroplasty was 23.4 degrees, and the combined ankle and midfoot motion was 31.3 degrees. The average improvement in ROM in the tibiotalar joint was approximately 5 degrees, and combined ROM was 6.1 degrees. Preoperative ROM proved to be the main factor determining the eventual postoperative ROM. It is possible to accurately measure the true ankle and the midfoot motion and those measurements should be used when reporting on the results of ankle replacements. Total ankle arthroplasty resulted in a statistically significant, but clinically less than expected, increase in ROM.

The Agility Total Ankle Arthroplasty

We previously reported the intermediate-term results with the early version of the Agility total ankle replacement, a unique design that takes advantage of arthrodesis of the tibiofibular syndesmosis for tibial component support. The purpose of this study was to report longer-term results of this procedure in the treatment of disabling ankle arthritis. We conducted an independent review of all Agility total ankle replacements performed by a single surgeon between 1984 and 1994. Follow-up evaluation consisted of completion of a validated ankle osteoarthritis scale and a short questionnaire and a review of the radiographs. All radiographs were evaluated for evidence of the development of progressive hindfoot arthritis, nonunion of the tibiofibular syndesmosis, progressive radiolucent lines, osteolysis, and component subsidence. One hundred and thirty-two arthroplasties were performed in 126 patients. After a mean follow-up period of nine years, thirty-three patients (thirty-six implants) had died, fourteen patients (11%) had a revision of the implant or an ankle arthrodesis, and one had the leg amputated because of an unrelated cause. Of the remaining seventy-eight patients (eighty-one ankles), sixty-seven (sixty-nine ankles) were followed clinically. More than 90% of them reported that they had decreased pain and were satisfied with the outcome of the surgery. We found modest differences in a comparison of the pain and disability scores with those of age-matched controls. Of the 117 ankles that had been followed radiographically for a minimum of two years, twenty-two (19%) had progressive subtalar arthritis, seventeen (15%) had progressive talonavicular arthritis, and nine (8%) had a syndesmosis nonunion. Eighty-nine (76%) of the 117 ankles had some evidence of peri-implant radiolucency. Arthrodesis of the tibiofibular syndesmosis impacts the radiographic and clinical outcomes with the Agility total ankle replacement. The relatively low rates of radiographic hindfoot arthritis and revision procedures at an average of nine years after the arthroplasty are encouraging. Agility total ankle replacement is a viable and durable option for the treatment of ankle arthritis in selected patients.