Scandinavian Total Ankle Replacement Research Articles

Mid- to Long-Term Outcomes of the STAR Total Ankle Replacement

Category: Ankle Arthritis; Ankle Introduction/Purpose: The Scandinavian Total Ankle Replacement (STAR) is a widely used ankle prosthesis, but mid- to long-term follow up remains limited. In thirteen different studies involving 939 STAR total ankle prostheses, the average duration of follow- up for recipients was 3.9 years. Thus, we sought to evaluate the STAR at the mid- to long-term interval with regards to survivorship, complications, and patient reported outcomes (PROs) in one of the largest series with the longest-term follow up to date. Methods: All patients managed with a primary STAR prosthesis at our institution from March 2002 through January 2017 were included in the analysis. Demographic characteristics including gender, race, age, diabetes status, body mass index (BMI), smoking status, American Society of Anesthesiologist (ASA) score, and surgery time were summarized. The cumulative incidence of implant failure was at 5 years and the last recorded time to event (8 years) were reported with 95% confidence intervals (CI). Paired t- tests were used to compare pre-operative and 5 year post-operative (±1 year) for PROs including Visual Analog Scale (VAS), Short Musculoskeletal Function Assessment (SMFA), Short-form-36 (SF-36), and American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot subscales. Additionally, intra- and post-operative complications were recorded. All statistical analysis were conducted in SAS 9.4 (Cary, NC). Statistical significance was assessed at α = 0.05. Results: 247 patients with a unilateral STAR procedure were included in this analysis. Demographics are listed in Table 1. The average number of years of follow-up was 5.71 ± 4.07 years. The cumulative incidence of implant failure at 5 years was 7.7% (95% CI 4.3%-12.5%). The last failure event occurred at 8 years post-implant. The cumulative incidence of implant failure at 8 years was 11.1% (95% CI 6.3%-17.3%) (Table 2, Figure 1). The most common post-operative complications were impingement (N = 39, 15.8%), ankle pain (N = 22, 8.9%), and implant failure (N = 16, 6.5%) (Table 3). With regards to PROs, patients significantly improved between baseline and 5-year follow up in all measures (all p< 0.001; Table 4). Conclusion: At mid- to long-term follow up, patients receiving the STAR prosthesis experienced a significant and durable improvement in PROs across multiple functional indices. Complication and failure rates were lower than those reported in previous series evaluating the STAR, with an observed survivorship of 88.9% at 8-year follow up.

High Rate of Talar Collapse in STAR Total Ankle

Category:Ankle; Ankle Arthritis; HindfootIntroduction/Purpose:Despite substantial advancements in Total Ankle Arthroplasty (TAA), catastrophic failure due to implant subsidence remains a common and serious problem. While there are many studies of short and some of intermediate term follow- up of TAA, the number of long-term studies, especially with prospectively collected data, is much fewer, and the data on the incidence and impact of talar subsidence on those results is even more limited. Talar subsidence can be especially challenging to manage, given the limited talar bone stock and revision options as compared to the larger tibial bone stock. The purpose of this study was to evaluate the long-term incidence and characteristics of TAA implant failure.Methods:A prospectively collected database of TAAs performed in a tertiary referral center began enrolling in 1999. Medical records/radiographs were reviewed to evaluate outcomes of TAA and final radiographs were reviewed to identify implant failure from 1999-2016. Minimum radiographic follow-up was two years. Pre-operative and post-operative radiographs were measured for ankle, foot, and implant coronal and sagittal alignment Failure and reoperation rates of two different implants, the mobile bearing Scandinavian Total Ankle Replacement (STAR) and the fixed bearing Salto Talaris (Salto) were analyzed. Paired Student t- tests were performed between groups. TAA revision surgeries were excluded if the primary TAA was performed at another institution. Reoperations were recorded according to the Reoperations Coding System (CROCS) classification of the Canadian Orthopaedic Foot and Ankle Society (COFAS). There were 149 TAAs reviewed in 146 patients (136 STARs and 13 Saltos), with an average follow-up of 7.03 years (range 2-20 years).Results:Implant survival was 85.8% at mean 7 years. 25 TAAs demonstrated radiographic catastrophic failures, 21 underwent re- operation, and 4 declined revision surgery (Table 1). One failure was due to infection (CROCS 10), others were aseptic (CROCS 9). 13/25 failures were related to talar subsidence, all STARs (9.6% of all STARs in the series). Nine STARs (6.4%) had less severe talar subsidence but were asymptomatic, The STAR talar component, in total, subsided in 17.6% (24/136) of STARs, requiring revision in 13 (9.6%) of cases at mean 3.8 years post-op. There was no difference in pre-operative/post-operative radiographic alignment between the TAAs that did and did not fail. Twenty-six ankles (17.4%) underwent additional surgery with retention of metal components, bringing the total reoperation rate to 47/149 (31.5%).Conclusion:At long-term follow-up, TAA demonstrates reasonable implant survival rates, especially given the learning curve that includes STARs implanted prior to the Food and Drug approval study. We describe a unique mode of failure in STARs that highlights one of the risk factors for failure in total ankle arthroplasty. This represents the highest reported rate of talar subsidence in the literature with almost 10% of STARs demonstrating talar-sided failure at mean 7-year follow-up. Surgeons who utilize the STAR total ankle should be vigilant for talar subsidence given the high rates reported in this series.

Effect of Packaging on Polyethylene Fractures, Implant Survivorship and Cyst Formation in Mobile Bearing Total Ankle Replacements

Category:Ankle Arthritis; AnkleIntroduction/Purpose:The Scandinavian Total Ankle Replacement (STAR) is the most widely used mobile bearing total ankle arthroplasty (TAA) in the US. The polyethylene component is ultrahigh molecular weight polyethylene and is designed to articulate with both the tibial and talar component. Initial data on the STAR in the US reported polyethylene fracture rates of greater than 10% as well as a concern for cyst formation due to osteolysis. The manufacturer changed the packaging to foil to prevent potential oxidation of the polyethylene, which could predispose the polyethylene to failure. The objective of the study was to evaluate a cohort of patients with STAR performed before and after converting to foil packaging to determine if there is a difference in polyethylene survivorship and cyst formation.Methods:All primary TARs performed by the senior author from 2010-2017 were reviewed. Patients with a minimum 48 month follow up were included in the study. The two groups were stratified by those performed prior to August 2014 (PRE) and those performed after August 2014 (POST). Preoperative and most recent postoperative alignment was determined on weight bearing radiographs. The outcomes included polyethylene fractures and cyst formation in the two groups. Cysts were defined as those measuring greater than 1cm2 on plain radiographs. Patients were recommended to have surgery if cyst volume was greater than 2cm2. Chi-squared tests were used to detect significant differences in the rate of cyst formation between the two groups. Paired t- tests were used to determine difference in preoperative versus postoperative alignment, follow up length, and polyethylene component thickness and patient age at time of procedure between the two groups.Results:The PRE group had 35 patients with an average follow up of 75 months (range 48-118). The POST group had 15 patients with average follow up 55 months (range 48-60). There was no difference in preoperative versus postoperative radiographic alignment between the groups (p>0.05). Cysts were present in 9 (26%) patients in the PRE group versus 4 patients (26%) in the POST group. Nine patients (26%) needed a second surgery due to cyst formation in the PRE group versus two (16%) in the POST group (p>0.05). Four patients (11%) had a fracture of the polyethylene in the PRE group with an average thickness of 6.7mm (range 6-9) and 77 months (range 68-84) versus zero in the POST group. The average time to polyethylene exchange for cyst(s) or polyethylene fracture was 58.3 months.Conclusion:This study suggests that changes in packaging to limit oxidation of the polyethylene from plastic to foil did not appear to represent a difference in periprosthetic cyst formation. However, there was a trend for additional surgery related to periprosthetic cysts and increased risk for polyethylene fracture in the PRE group. These results could suggest the potential for oxidation changes that alter the wear characteristics and fragility of the polyethylene component. Confounding factors could include postoperative time and component thickness. Further investigation and longer follow-up will be needed to further delineate oxygenation impacts on TAA polyethylene components.

2021 Roger A. Mann Award Winner: Long-Term Revision Rates and Functional Outcomes of Total Ankle Arthroplasty and Ankle Arthrodesis

Category:Ankle Arthritis; AnkleIntroduction/Purpose:Recent studies have shown acceptable long-term survival rates with TAA however there remains a general paucity of information directly comparing ankle arthroplasty to arthrodesis over long-term follow-up. This study compares revision rates and functional outcomes for a large cohort of patients undergoing ankle arthrodesis or arthroplasty. All surgeries were performed by a single surgeon from 1999 to 2013. Ankle arthrodesis was performed using a standardized 3-screw technique with anterior plate supplementation. Arthroplasty was performed utilizing the Scandinavian Total Ankle Replacement (STAR) prosthesis.Methods:A retrospective chart review was performed for 335 consecutive cases in 326 patients (198 ankles in the arthrodesis group and 137 in the arthroplasty group). Patient demographics including age, sex, body mass index (BMI), and preoperative diagnoses were collected. Foot Function Index (FFI) scores were obtained and recorded at final outpatient follow-up. Primary outcomes included the rate of revision surgery and functional outcome scores. Secondary outcomes included perioperative complications such as polyethylene fracture and patients who went on to undergo postoperative subtalar fusion for symptomatic adjacent joint arthritis.Results:Ten (6%) ankles in the arthrodesis group and twenty-one (15%) in the arthroplasty group required revision surgery at a mean of 8.9 +- 6.5 and 61.1 +- 52.9 months, respectively [P=.039]. One hundred four of the 335 cases were available to complete functional outcome surveys at final follow-up at a mean of 11.2 +- 4.1 years from time of surgery (minimum 6-year follow-up).Mean FFI scores were significantly better in the arthroplasty group (40.3 +- 36.9) than in the arthrodesis group (61.5 +- 45.1) [P=.011]. Thirteen polyethylene components in 12 TAAs (8.7%) required replacement for fracture at an average of 9.6 +- 4.2 years postoperatively. Seven (3.5%) cases in the arthrodesis group and three (2.2%) in the arthroplasty group went on to undergo subtalar fusion at an average of 4.9 +- 3.9 years post-operation [P=.536].Conclusion:Long-term functional outcome scores were better in TAA patients; however, the revision rate for major complications was found to be greater over time. While the ankle arthroplasty group did show a slightly lower frequency of adjacent joint arthritis progression leading to subsequent subtalar fusion, this difference was not statistically significant. To our knowledge, this is the largest and longest-term follow-up comparing the STAR prosthesis to ankle arthrodesis published in the United States to date.

Functional Outcomes of Total Ankle Arthroplasty at a Mean Follow-up of 7.6 Years: A Prospective, 3-Dimensional Gait Analysis.

In vivo gait analysis provides objective measurement of patient function and can quantify that function before and after ankle reconstruction. Previous gait studies have shown functional improvement for up to 4 years following total ankle arthroplasty (TAA), but to date, there are no published studies assessing function at ≥5 years following TAA. We hypothesized that patients who underwent TAA would show significant improvements in walking function at a minimum follow-up of 5 years, compared with their preoperative function, as measured by changes in temporospatial, kinematic, and kinetic gait parameters. Three-dimensional gait analysis with a 12-camera digital motion-capture system and double force plates was utilized to record temporospatial, kinematic, and kinetic measures in 33 patients who underwent TAA with either the Scandinavian Total Ankle Replacement (Stryker; n = 28) or Salto Talaris Ankle (Integra LifeSciences; n = 5). Gait analysis was performed preoperatively and at a minimum follow-up of 5 years (mean, 7.6 years; range, 5 to 13 years). Significant improvements were observed in multiple gait parameters, with temporospatial increases in cadence (+9.5 steps/min; p < 0.0001), step length (+4.4 cm; p = 0.0013), and walking speed (+0.2 m/s; p < 0.0001), and kinematic increases in total sagittal range of motion (+2.0°; p = 0.0263), plantar flexion at initial contact (+2.7°; p = 0.0044), and maximum plantar flexion (+2.0°; p = 0.0488). Kinetic analysis revealed no loss of peak ankle power, despite patients aging. To our knowledge, this is the first study to report 7-year functional outcomes of TAA, quantified by objective, in vivo measurements of patient gait. Patients were shown to have sustained improvement in multiple objective parameters of gait compared with preoperative function. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Finite element analysis of bone‐prosthesis interface micromotion for cementless talar component fixation through critical loading conditions

The total ankle replacement (TAR) survivability rate is still suboptimal, and this leads to many orthopaedic surgeons opting arthrodesis as a better option for the ankle arthritis patients. One of the fundamental reasons is due to the lack of primary stability of the prosthesis fixation at the bone-prosthesis interface hence leading to long-term aseptic loosening of the talar component. The commercially available Scandinavian Total Ankle Replacement (STAR) Ankle design and several additional design features (including trabecular metal, side fin, double fin, and polka-dot designs) were studied using finite element analysis, and the bone-prosthesis interface relative micromotion (BPIRM) and talar bone minimum principal stresses were examined and analysed. Three loading conditions at a gait cycle of heel strike, midstance, and toe off with different meniscal bearing displacement were also included as part of the study parameters. The results were correlated to in vitro cadaveric measurements and reported clinical studies. Simulated results showed that the de-bonding relative distance between the bone and prosthesis upon loading (COPEN defined by the simulation software) was the main reason constituting to the high interface micromotion between the talar component and talus bone (which could lead to long-term aseptic loosening). The polka-dot design was shown to induce the lowest BPIRM among all the designs studied.

The Outcomes of Bone Grafting of Peri-Prosthetic Total Ankle Osteolytic Lesions: A Meta-Analysis

Category:AnkleIntroduction/Purpose:Total ankle replacement (TAR) has become an increasingly popular alternative to ankle arthrodesis as a treatment option for end-stage ankle arthritis. However, total ankle implants are not without short and long-term complications and one of the most common is peri-prosthetic osteolysis, Many studies have been done on the incidence of peri-prosthetic bone cysts as well as the etiology, but there have been limited reports on the optimal management of these lesions. The most widely accepted method of treatment is curettage and grafting of the lesion with or without polyethylene exchange. Our aim was to perform a systematic review of the literature on the outcome of bone grafting in the management of periprosthetic osteolytic following TAR.Methods:Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, Medline, PubMed, Scopus, and Google Scholar databases were searched in November and December 2018 for all observational or experimental studies that evaluated bone grafting of peri-prosthethic total ankle osteolytic cysts. The primary outcome was the rate of major revision to either component replacement or ankle arthrodesis and the secondary outcome was the rate of radiological cyst progression after grafting. Descriptive, quantitative, and qualitative data were extracted.Results:Of the 70 articles identified, 6 studies were eligible for the meta-analysis for a total of 120 patients with 123 total ankle replacements. Average age of subjects was 58.5 years. 4 papers included details of patient gender revealing 50 males and 26 females in those studies. The most common type of total ankle replacement was the Ankle Evolutive System(AES) followed by the Scandinavian total ankle replacement (STAR). With an average follow up 5.1 years (1.4-15.4), the rate of conversion to major revision after curettage and bone grafting was 15% (7.6%- 22.4%). Despite that apparent success, there was a 40.4% (5.4%-75.4%) rate of radiological cyst progression after graftingConclusion:Our systematic review shows that curettage and bone grafting of the osteolytic lesions around TAR is safe procedure which can increase the survivorship of the implant and delay the need for further major surgeries. Providing better bone stock for later revision may also be of benefit. However, the high rate of cyst progression is worrisome for future complications. This highlights the need to further research the etiology of the cyst and to explore treatments aimed at eliminating the cause of cysts to prevent the need for repeat procedures and the potential for implant failure.

Total ankle arthroplasty: long-term survival and factors that influence it

TAA and ankle arthrodesis are efficacious treatments of end-stage ankle osteoarthritis but the selection must be specially fit to individual patients. Total ankle arthroplasty (TAA) offers a judicious option to ankle arthrodesis in prudently selected patients. Reoperation rates are greater in TAA compared with ankle arthrodesis. The primary diagnosis for TAA is 37% osteoarthritis, 34% traumatic arthritis, 15% rheumatoid arthritis, 14% other. Patients experiencing TAA tend to be older, female, and have rheumatoid arthritis compared with those being subjected to ankle arthrodesis. Aseptic loosening and infection are the most frequent complications of TAA needing revision. The 15-year survival of primary TAA ranges from 45% to 91%. A comparison between the HINTEGRA implant, the AGILITY implant, the MOBILITY implant, and the Scandinavian Total Ankle Replacement (STAR) implant exhibited reasonable results of four modern TAA designs. TAA is a demanding surgical technique and the survival is not similar to that following hip or knee arthroplasty. Revision TAA has a 10-year survival of 55%, which is lower than the 10-year survival of 74% for primary TAA.

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

Survivorship and long-term outcome of a consecutive series of 200 Scandinavian Total Ankle Replacement (STAR) implants.

We report the long-term clinical and radiological outcomes of a consecutive series of 200 total ankle arthroplasties (TAAs, 184 patients) at a single centre using the Scandinavian Total Ankle Replacement (STAR) implants. Between November 1993 and February 2000, 200 consecutive STAR prostheses were implanted in 184 patients by a single surgeon. Demographic and clinical data were collected prospectively and the last available status was recorded for further survival analysis. All surviving patients underwent regular clinical and radiological review. Pain and function were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scoring system. The principal endpoint of the study was failure of the implant requiring revision of one or all of the components. Kaplan-Meier survival curves were generated with 95% confidence intervals and the rate of failure calculated for each year. A total of 84 patients (87 ankles) were alive by the end of this study. Of the surviving 84 patients (87 ankles; rheumatoid arthritis (RA), n = 40; OA, n = 47), 45 were women and 39 were men, with a mean age of 54 years (18 to 72 years) at the time of surgery. A total of 32 implants failed (16%), requiring revision surgery. The mean time to revision was 80 months (2 to 257). The implant survival at 15.8 years, using revision as an endpoint, was 76.16% (95% confidence interval (CI) 64.41 to 87.91). We found a steady but low decrease in survival over the study period. The mean AOFAS score improved from 28 (10 to 52) preoperatively to 61 (20 to 90) at long-term follow-up. STAR prostheses in the United Kingdom have now been largely superseded by newer design TAAs, potentially with improved characteristics and surgical techniques. The long-term survivorship for the STAR prosthesis can provide a benchmark for these later designs of ankle arthroplasty.

Total Ankle Arthroplasty: Long-term Survival and Factors that Influence it

TAA and ankle arthrodesis are efficacious treatments of end-stage ankle osteoarthritis but the selection must be specially fit to individual patients. Total ankle arthroplasty (TAA) offers a judicious option to ankle arthrodesis in prudently selected patients. Reoperation rates are greater in TAA compared with ankle arthrodesis. The primary diagnosis for TAA is 37% osteoarthritis, 34% traumatic arthritis, 15% rheumatoid arthritis, 14% other. Patients experiencing TAA tend to be older, female, and have rheumatoid arthritis compared with those being subjected to ankle arthrodesis. Aseptic loosening and infection are the most frequent complications of TAA needing revision. The 15-year survival of primary TAA ranges from 45% to 91%. A comparison between the HINTEGRA implant, the AGILITY implant, the MOBILITY implant, and the Scandinavian Total Ankle Replacement (STAR) implant exhibited reasonable results of four modern TAA designs. TAA is a demanding surgical technique and the survival is not similar to that following hip or knee arthroplasty. Revision TAA has a 10-year survival of 55%, which is lower than the 10-year survival of 74% for primary TAA.

Intermediate-term Experience With the STAR Total Ankle in the United States.

Limited intermediate and no real long-term follow-up data have been published for total ankle arthroplasty (TAA) in the United States. This is a report of clinical follow-up data of a prospective, consecutive cohort of patients who underwent TAA by a single surgeon from 1999 to 2013 with the Scandinavian Total Ankle Replacement (STAR) prosthesis. Patients undergoing TAA at a single US institution were enrolled into a prospective study. These patients were followed at regular intervals with history, physical examination, and radiographs; American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Scale scores were obtained and recorded. Primary outcomes included implant survivability and functional outcomes scores. Secondary outcomes included perioperative complications such as periprosthetic or polyethylene fracture. Between 1999 and 2013, a total of 138 STAR TAAs were performed in 131 patients; 81 patients were female. The mean age at surgery was 61.5 ± 12.3 years (range, 30-88 years). The mean duration of follow-up for living patients who retained both initial components at final follow-up was 8.8±4.3 years (range 2-16.9 years). The mean change in AOFAS Ankle-Hindfoot scores from preoperative to final follow-up was 36.0 ± 16.8 ( P < .0001). There were 21 (15.2%) implant failures that occurred at a mean 4.9 ± 4.5 years postoperation. Ten polyethylene components in 9 TAAs (6.5%) required replacement for fracture at an average 8.9 ± 3.3 years postoperatively. Fourteen patients died with their initial implants in place. This cohort of patients with true intermediate follow-up after TAA with the STAR prosthesis had acceptable implant survival, maintenance of improved patient-reported outcome scores, and low major complication rates. Level IV, case series.

Survival of the Scandinavian Total Ankle Replacement (STAR)

Category: Ankle Arthritis Introduction/Purpose: The purpose of this study was to evaluate survival and clinical outcome of the Scandinavian total ankle replacement (STAR) prosthesis after a minimum of ten years up to a maximum of 19 years. Methods: Fifty STAR prostheses in 46 patients with end stage ankle osteoarthritis operated between 1996 and 2006 by the same surgeon (MH) were included. Minimal follow-up was ten years (median 14.6 years, 95% confidence interval [CI] 12.9-16.4). Clinical (Kofoed score) and radiological assessments were taken before the operation and at one, ten (+2), and 16 (±3) years after implantation. The primary endpoint was defined as exchange of the whole prosthesis or conversion to arthrodesis (def. 1), exchange of at least one metallic component (def. 2), or exchange of any component including the inlay (due to breakage or wear) (def. 3). Survival was estimated according to Kaplan-Meier. Further reoperations related to STAR were also recorded. Results: The ten year survival rate was (def. 1) 94% (CI 82- 98%), (def. 2) 90% (CI, 77-96%), and (def. 3) 78% (CI 64-87%). The 19-year survival rate was (def. 1) 91% (CI 78-97%), (def. 2) 75% (CI 53-88%), and (def. 3) 55% (CI 34-71%). Considering any re-operations related to STAR, 52% (26/50) of prostheses were affected by re-operations. Mean pre-operative Kofoed score was 49, which improved to 84 after one year (n = 50), to 90 after ten years (n = 46), and to 89 after 16 years (n = 28). Conclusion: The survival rate for def. 1 and 2 was high. However, re-operations occurred in 52% of all STAR prosthesis.

Quality of Modern Total Ankle Arthroplasty Research

Category: Ankle Arthritis Introduction/Purpose: Total ankle arthroplasty (TAA) is gaining popularity as an alternative to ankle arthrodesis in the setting of end-stage ankle arthritis. However, compared to hip and knee arthroplasty, there is a relative dearth of evidence to support its use. This study assesses the quality of literature surrounding modern TAA designs. Methods: A search of all peer-reviewed, English-language journals was conducted to identify publications involving TAA. The initial search identified 444 articles published during 2006-2016. Of these, 182 were excluded because they were not clinical outcomes studies, 46 because the TAA implant was no longer available, and 15 because the primary outcome of the study was not related to TAA, leaving 201 articles for analysis. Results: No Level I studies were identified. Seventeen (8%) studies were Level II, 48 (24%) Level III, 128 (64%) Level IV, and 8 (4%) Level V. One hundred forty-three studies (71%) were retrospective in nature. Stratification by study design revealed 128 (64%) case series, 33 (16%) experimental cohort studies, 19 (10%) case-control studies, 13 (6%) observational cohort studies, and 8 (4%) case reports. The number of studies published each year steadily increased from 2006 to 2016. A total of 51% of TAA research was published in only two journals: Foot and Ankle International and the Journal of Bone and Joint Surgery. Publications from the United States accounted for 36% of total publications. The most published implant was the Scandinavian Total Ankle Replacement (Figure 1). Conclusion: While the number of TAA studies published each year has steadily increased since 2006, the quality of this research as measured by level of evidence remains suboptimal. This analysis highlights the need for continued improvement in methodology and development of robust prospective registries to advance our knowledge of TAA as a treatment for end-stage ankle arthritis.

Outcomes of Total Ankle Arthroplasty in Moderate and Severe Valgus Deformity

Category: Ankle Arthritis Introduction/Purpose: Among patients with end-stage ankle arthritis, total ankle arthroplasty (TAA) utilization has significantly increased in recent years, while ankle arthrodesis utilization has declined. Significant coronal plane deformity is frequently encountered in this patient population, and was previously considered a contraindication to TAA. However, the advent of newer fixed-bearing prostheses, coupled with improved surgical techniques and a better understanding of ligamentous balancing, have allowed surgeons to extend their indications for TAA with respect to deformity correction. Several authors have demonstrated good outcomes from TAA in patients with significant varus deformities, but not specifically in patients with valgus deformities. We aimed to determine the clinical, radiographic, and patient-reported outcomes of patients with moderate to severe valgus deformity who underwent TAA for end-stage ankle arthritis. Methods: Eighty patients with valgus deformities =10 degrees who underwent TAA were retrospectively reviewed. All surgeries were performed by one of three fellowship-trained orthopaedic foot and ankle surgeons with extensive experience in TAA. One of three prostheses were used: INBONE (Wright Medical Technology, Arlington, TN), Salto-Talaris (Integra, Plainsboro, NJ), or the Scandinavian Total Ankle Replacement (STAR; Stryker, Kalamazoo, MI). We assessed the coronal tibiotalar angle on standardized weightbearing radiographs preoperatively, at one year, and at final follow-up. The visual analog scale (VAS) for pain, Short Form (SF)-36 scale, American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot-ankle scale, and Short Musculoskeletal Function Assessment (SMFA) scores were assessed preoperatively and at final follow-up. Subgroup analyses were performed to determine differences in outcome scores, deformity correction, and maintenance of alignment between patients with moderate (=10 degrees, &lt;20 degrees) and severe (&gt;20 degrees) preoperative deformity. Complication, reoperation, and revision rates were collected from chart review. Results: Mean preoperative valgus deformity was 15.5 ± 5.0 degrees, and was corrected to a mean 1.2 ± 2.6 degrees of valgus postoperatively (Figure; P&lt;.001). An associated flatfoot deformity was present in 33% of patients, 65% of whom required concomitant procedures to address associated deformity. The VAS, SF-36, AOFAS, and SMFA scores improved significantly postoperatively (P&lt;.001 for all), with no difference in amount of improvement between the moderate and severe deformity groups. Deformity correction was maintained at a mean 3.5 (range 2.0-5.9) years of follow-up, with no significant change in the mean tibiotalar angle between one year and final follow-up in either the moderate or severe deformity groups (P=.134 and P=.155, respectively). Reoperation and revision rates did not differ between the moderate and severe deformity groups. Conclusion: Correction of coronal alignment was achieved and maintained following TAA in patients with both moderate and severe preoperative valgus malalignment. Patients demonstrated significant improvement in patient-reported outcome scores regardless of amount of preoperative deformity. Additional procedures may be necessary at the time of TAA to balance the ankle and correct associated deformity in the foot.

Salvage arthrodesis of a failed total ankle replacement using a custom 3D-printed cage implant: A case report and review of the literature

We present a case report of a 66-year-old female who underwent salvage arthrodesis after a failed Scandinavian Total Ankle Replacement secondary to aseptic loosening and talar subsidence. Secondary to the loss of talar integrity the decision was made to proceed with revisional ankle arthrodesis. To maintain limb length the primary surgeon (EH) elected to use a custom cage implant in combination with an intramedullary nail construct in a single stage approach. The custom cage was augmented with autograft &amp; allograft cancellous bone in addition to allograft recombinant human bone morphogenic protein, and allograft adult mesenchymal stem cells. The incision sites healed post-operatively without incident and at post-op week 16 the patient progressed to full unrestricted weight bearing in normal shoe wear with a gauntlet ankle brace. Although an isolated report, this case shows promise for further development of the technique. We believe this revisional arthrodesis technique warrants further research and consideration as a potential addition to the failed total ankle arthroplasty treatment algorithm.

Scandinavian Total Ankle Replacement: 15-Year Follow-up.

Over the past decade, total ankle arthroplasty (TAA) has become a mainstay in the treatment of end-stage ankle arthritis. Currently in its fourth generation, the Scandanavian Total Ankle Replacement (STAR) is the only 3-piece mobile bearing ankle prosthesis available in the United States. Our current study reports implant survivorship at 15 years and patient outcomes for a subset of these survivors available for study. Eighty-four TAAs were performed between 1998 and 2000. Metal component survivorship at 15 years was calculated with a Kaplan-Meier curve. Twenty-four (29%) of 84 patients were available for participation with a minimum 15-year follow-up. Any radiographic changes were documented. All additional procedures and complications were recorded. Clinical findings, self-reported performance and pain evaluations, and AOFAS ankle/hindfoot scores were noted. Metal implant survival was 73% at 15 years. Of the 24 patients available for clinical evaluation, 18 of 24 patients (70.7%) had no change in prosthetic alignment from the immediate postoperative radiograph. Only 1 subtalar fusion was required for symptomatic adjacent joint arthritis. Three patients sustained a broken polyethylene component. AOFAS scores improved from an average of 39.6 points preoperatively, to an average of 71.6. More than half (52.4%) of patients with retained implants required an additional surgical procedure; 3 required 2 additional procedures. The average time to subsequent procedure was 10.2 years. Our small cohort demonstrated STAR ankles with retention at 9 years were highly likely to survive to 15 years, and patients continued to have significant improvement in pain relief and minimal decrease in function. At 15 years from TAA, metal survivorship was 73%. As with all ankle replacements, supplementary procedures were common. Level IV, case series.

Survival of the Scandinavian total ankle replacement (STAR): results of ten to nineteenyears follow-up.

The purpose of this study was to evaluate survival and clinical outcome of the Scandinavian total ankle replacement (STAR) prosthesis after a minimum of tenyears up to a maximum of 19years. Fifty STAR prostheses in 46 patients with end stage ankle osteoarthritis operated between 1996 and 2006 by the same surgeon (MH) were included. Minimal follow-up was tenyears (median 14.6years, 95% confidence interval [CI] 12.9-16.4). Clinical (Kofoed score) and radiological assessments were taken before the operation and at one, ten (+2), and 16 (±3) years after implantation. The primary endpoint was defined as exchange of the whole prosthesis or conversion to arthrodesis (def. 1), exchange of at least one metallic component (def. 2), or exchange of any component including the inlay (due to breakage or wear) (def. 3). Survival was estimated according to Kaplan-Meier. Further reoperations related to STAR were also recorded. The ten year survival rate was (def. 1) 94% (CI 82-98%), (def. 2) 90% (CI, 77-96%), and (def. 3) 78% (CI 64-87%). The 19-year survival rate was (def. 1) 91% (CI 78-97%), (def. 2) 75% (CI 53-88%), and (def. 3) 55% (CI 34-71%). Considering any re-operations related to STAR, 52% (26/50) of prostheses were affected by re-operations. Mean pre-operative Kofoed score was 49, which improved to 84 after one year (n=50), to 90 after ten years (n=46), and to 89 after 16years (n=28). The survival rate for def. 1 and 2 was high. However, re-operations occurred in 52% of all STAR prosthesis. Retrospective cohort study, evidence Level 4.

Long-term Results of Scandinavian Total Ankle Replacement.

The purpose of this study was to evaluate the long-term results of the Scandinavian Total Ankle Replacement (STAR) implant in a single center. Between 1997 and 2002, 34 consecutive ankles were replaced with the STAR ankle prosthesis and reviewed in 2016. Patients were followed both radiologically and clinically; clinical outcomes were measured with the Kofoed ankle score and subjective measurements. The median follow-up period was 159 months (13.3 years; range, 13-202 months). The implant survival rate was 93.9% (95% confidence interval [CI], 92.2%-86.7%) at 5 years, 86.7% (95% CI, 69.3%-96.2%) at 10 years, and 63.6% (95% CI, 30.8%-89.0%) at 15 years. A total of 15 ankles (44%) had been revised: 2 by fusion, 3 by further replacement, 5 by insert exchange, and 5 by bone grafting for marked osteolysis. The improvements in the Kofoed ankle score and Kofoed ankle score for pain were statistically significant at every postoperative evaluation point compared to the preoperative values (all P < .0001), and subjective patient satisfaction was high. Our results were satisfactory and in agreement with previously reported findings of STAR implants. Level IV, retrospective case series.

A Prospective Study of Four Total Ankle Arthroplasty Implants by Non-Designer Investigators.

There are several types of prostheses available to surgeons when performing a total ankle arthroplasty (TAA). The main objective of this study was to summarize the clinical and functional outcomes of 4 TAA prostheses: the Hintegra implant (Integra LifeSciences), the Agility implant (DePuy), the Mobility implant (DePuy), and the Scandinavian Total Ankle Replacement (STAR) implant (Small Bone Innovations [SBi]). Patients were prospectively recruited. A total of 451 TAAs with a mean follow-up (and standard deviation) of 4.5 ± 2.0 years were included. Patients were assessed annually and completed self-reported outcome measures at these visits. Complications and revisions were reported at the time of incident. Mean improvements are reported by prosthesis. Linear mixed-effects models were used to obtain adjusted comparisons of scores across prostheses. Survivorship curves were generated by prosthesis and type of complication. Mean improvement in the Ankle Osteoarthritis Scale (AOS) total score was less among patients with the Mobility implant (19.5; 95% confidence interval [CI], 15 to 24) than it was among patients with the Agility implant (29.1; 95% CI, 24 to 34), Hintegra implant (29.7; 95% CI, 27 to 33), and STAR implant (28.5; 95% CI, 23 to 34). Patients in the Mobility group also had less mean improvement in the AOS pain score (21.3; 95% CI, 17 to 26) compared with patients in the Hintegra (29.0; 95% CI, 26 to 32), Agility (29.8; 95% CI, 25 to 35), and STAR (29.1; 95% CI, 23 to 35) groups. The Mobility group also had less mean improvement in the AOS disability score (17.3; 95% CI, 12 to 23) compared with the Hintegra (30.4; 95% CI, 27 to 34), Agility (28.8; 95% CI, 23 to 34), and STAR (27.8; 95% CI, 21 to 34) groups. Survival results among the 4 prostheses are reported. This study demonstrated acceptable outcomes of 4 modern TAA prostheses. Outcome results from patient-reported scores were comparable between at least 3 of the 4 prostheses (the Hintegra, STAR, and Agility implants). The rates of complications and revisions found in this study are within the limits reported in the literature for similar prostheses and methods of reporting. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.