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Category: Other Introduction/Purpose: Natural Language Processing (NLP) can aid in navigating and synthesizing vast amounts of text data. Topic modeling, a subset of NLP, can identify topics and trends that might otherwise remain obscured in large text datasets. These techniques can be used to assess the dynamic and rapidly growing landscape of the orthopedic literature quickly and objectively. The field of foot and ankle orthopaedic research is rapidly changing with the evolution and implementation of new techniques and implants. This study employed an advanced topic model (Bidirectional Encoder Representations from Transformers Topic (BERTopic) Model), to analyze the trends and key topics in Foot & Ankle International literature from 1980 to 2023. Methods: Text from the titles and abstracts of 4945 original articles & reviews published from 1980 to 2023 were included and used to train the BERTopic AI model. AI-generated topics were then analyzed by frequency (i.e. number of studies classified to that topic) & popularity (i.e. "hot" & "cold" topic trends, based on linear regression models of topic frequency from 2018-2023). The BERTopic model yielded 41 distinct topics. Results: The top 10 most common topics from 1980-2023 (Figure 1A) were Hallux Valgus: Treatment, Ankle Replacement, Diabetic Foot Disease, Achilles Injury and Treatment, Plantar Fasciitis, Pes Planus: Treatment, Calcaneal Fractures, Osteochondral Lesions of the Talus, Plantar Foot Pressure, and Peroneal Tendon Tears. The most popular or "hot" topics from 2018-2023 (Figure 1B) were Pes Planus: Radiographical Assessment of Foot Alignment, Hallux Valgus: Biomechanics, Ankle Arthrodesis, Ankle Instability: Deltoid Ligament, Ankle Replacement, Achilles Injury and Treatment, Tarsal Tunnel, Bone Grafting, Supramalleolar Osteotomy, and Peroneal Tendon Tears; while the least popular or "cold" topics were Ankle Replacement: Surveys, Hallux Valgus: Treatment, Calcaneal Fractures, Osteochondral Lesions of the Talus, Hallux Rigidus: Treatment, Chronic Ankle Instability, Foot and Ankle-specific Patient Reported Outcome Measures, Syndesmotic Instability, and Lisfranc Injuries. Conclusion: This study demonstrates the power of AI in efficiently distilling and analyzing evolving research topics and trends, as well as the dynamic nature of foot and ankle orthopaedic research. The hottest topics over the past 5 years were Pes Planus: Radiographical Assessment of Foot Alignment, Hallux Valgus: Biomechanics, Ankle Arthrodesis, and Ankle Instability. However, recent years have seen increases in publications regarding total ankle replacement. These techniques may be used to complement traditional literature reviews and meta-analyses. [ABSTRACT FROM AUTHOR]

Category: Basic Sciences/Biologics; Midfoot/Forefoot Introduction/Purpose: Interfragmentary stability and compression are ideal for bone healing in fracture repair and arthrodesis procedures. The primary purpose of orthopaedic plate and screw hardware is to provide interfragmentary stability with a lesser focus on interfragmentary compression as this is typically achieved with lag screw fixation outside of the plate, before plate application. Modern plates afford variable screw angulation with the intended purposes to capture bony fragments or avoid other hardware but not for compression. We hypothesized that variable angle technology can be used to pull bony fragments together, thereby optimizing interfragmentary compression and contact area. However, there is no data to support this rationale. This study aimed to elucidate the impact of "highly-angled" screw angulation to optimize interfragmentary compression and contact area for bony healing. Methods: Interfragmentary fixation was simulated using interlocking orthopedic plates on simulated fractures in foam bone models (SawBones). To ensure findings were not specific to plate model, two orthopedic plate models were tested (Plate 1 = 4-hole plate, Max Screw Angle=15°, Plate 2 = 4-hole plate, Max Screw Angle=30°). Plates were applied to the bone fragments according to manufacturer instructions FigA. Screws were inserted (1) perpendicular to the plate (0°), (2) angled 15° away from fracture line, or (3) angled 30° away from fracture line (Plate 2 only as this exceeds max angulation of Plate 1). Interfragmentary compression and contact area were measured following application of all screws using pressure sensing film (TekScan Evolution). Data were analyzed using a two-way ANOVA with plate model and screw angle as main effects. Results: Interfragmentary compression markedly and significantly increased with increasing screw angle (p< 0.001,Fig1B). Specifically, mean interfragmentary compression across both plate groups increased by 470% in the 15° screw angle group as compared to the 0° group. When screws were applied at 30° offset from fracture plane, compression was increased by 956% as compared to the 0° group. The Plate 2 group demonstrated significantly increased compression across all screw angles as compared to the Plate 1 group (p=0.045,FigB). Contact area increased significantly with increased screw angle (p< 0.001, FigC). No significant differences in contact area were noted between plate groups (p=0.81, FigC). Conclusion: Our findings underscore the critical role of screw angulation in achieving optimal interfragmentary compression and contact area. Specifically, even a modest 15° screw angle significantly enhanced interfragmentary compression and contact area by 470% and 212%, respectively. Importantly, these data highlight that maximum allowable screw angulation provided by plate models is a key factor in enhancing fixation quality. Surgeons should consider utilizing plates offering greater that offer maximum angulation flexibility to optimize fixation quality. This approach not only affords improved compression but also allows for improved adaptation to the anatomical and intraoperative challenges, offering a substantial advancement in fracture stabilization techniques. [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: Recent literature, particularly in the fields of total joint arthroplasty, has raised concern for increased perioperative complications following joint arthroplasty in patients with osteoporosis. The purpose of this study is to evaluate the influence of preoperative osteoporosis on 6-month postoperative outcomes following total ankle arthroplasty (TAA). Methods: The Nationwide Readmissions Database (NRD) was queried from 2015-2020 to identify 29,705 patients undergoing primary elective TAA. Patients were divided into two cohorts based on the presence of preoperative osteoporosis (as defined by ICD-10 CM codes M81, M80, M80.07XX), with 943 (3.3%) having this diagnosis. Preoperative demographics, comorbidities, postoperative outcomes, cost of admission, and total length of stay (LOS) were analyzed between cohorts. Multivariate regression analyses were conducted to control for predictors of adverse postoperative outcomes other than preoperative osteoporosis. Results: The overall cohort was majority male (54.2%) with mean age of 64.15 (range 17-90) years, and Charlson-Deyo Comorbidity Index (CCI) score of 0.65 (range 0-12). Patients diagnosed with preoperative osteoporosis patients were statistically significantly older (Osteoporosis=68.72 years; non-osteoporosis=65.03 years; p<.001), more likely to have Medicare insurance (p<.001), and had a higher CCI score (Osteoporosis=0.98; Non-Osteoporosis=0.64; p<.001). Multivariate regression analysis of 180-day postoperative outcomes found that preoperative osteoporosis was significantly predictive of increased risk of any complication (OR=1.428; p<.001), transfusion (OR=3.370; p<.001), pulmonary embolism (OR=5.625; p=.016), Pneumonia (OR=3.872; p<.001), adverse discharge (OR=1.445; p<.001), and extended stay greater than 4 days (OR=1.310; p<.001). Further, the presence of osteoporosis is predictive of nearly a $3,000 increase in total cost of procedure (β= 2980.22; p<.001). Conclusion: The presence of osteoporosis was significantly predictive of higher rates of postoperative complications, LOS, and a substantially higher cost of procedure following TAA. Physicians and patients alike should consider this comorbidity when stratifying risk for outcomes following total ankle arthroplasty. [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: The incidence of total ankle arthroplasty (TAA) continues to increase as outcomes and surgeon comfort with the procedure improve. There is a paucity of literature investigating the association between operative time (case duration) and postoperative outcomes following TAA. Thus, this study seeks to evaluate the relationship between total operative time and postoperative outcomes following TAA. We hypothesize that increased operative time is statistically significantly associated with an increased risk of 30-day postoperative complications in patients undergoing total ankle arthroplasty. Methods: The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database was queried from 2007-2020 to identify 2,133 patients undergoing TAA. Demographics, medical comorbidities, concomitant procedures, hospital length of stay (LOS), and 30-day complication, readmission, and reoperation rates were compared between groups. Patients were excluded based on an operative time greater than 290 minutes (based on Inter-Quartile Range [IQR] proximity rule) to limit the influence of extreme outliers. The cohort was predominantly male (53.8%) and mean patient age was 64.10 (range 19-87) years with a mean BMI of 31.00 (range 17.14-57.78) m/kg2. The mean operative time of the cohort was 149.56 (standard deviation [SD]=49.60) minutes. Results: Demographic characteristics associated with increased operative time were younger age (p <.001), functionally dependent status (p=.041), general anesthesia instead of spinal (p <.001), not having diabetes (p <.001), and not having COPD (p=.005). Multivariate analysis, accounting for these variables, revealed that a 15-minute increase in operative time led to an increase in risk of any complication by 10% (p=.019), wound dehiscence by 30% (p=.005), urinary tract infection by 38% (p=0.009), readmission by 16% (p=0.003), reoperation by 16% (p=0.048), and extended length of stay by 6% (p=0.023). Increased operative (>1 SD above the mean), independently predicted readmission (OR=2.817; 95%CI=1.334-5.951; p=0.007), urinary tract infection (OR=6.410; 95%CI=1.384-29.6866; p=0.018), wound dehiscence (OR=5.127; 95%CI=1.282-20.508; p=0.021), and bleeding requiring transfusion (OR=18.364; 95%CI=1.846-182.682; p=0.013). Conclusion: The study found longer operative time during TAA is associated with a statistically significant increase in complications, including wound dehiscence, urinary tract infection, readmission, reoperation, and increased length of stay. Therefore, surgeons should prioritize measures to reduce operative time when appropriate while optimizing implant placement, deformity correction, and implant stability in TAA. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Ankle Introduction/Purpose: End stage talar avascular necrosis (AVN) is a difficult diagnosis to manage clinically. Management options will vary based on severity and functional goals with current treatments including conservative measures, hindfoot fusions, and total talus replacement (TTR). The induction of three-dimensional (3D) printing and computer-aided design (CAD) into orthopaedic surgery has increased the ability to treat this complex pathology through patient specific 3D printed talus replacements, while sacrificing less range of motion than joint fusions. This purpose of this study is to report prospectively collected clinical and patient reported outcome measures (PROMs) of patients implanted with a custom 3D printed TTR in a multi-institutional prospective study. Methods: Patients presenting to clinic for talar avascular necrosis at one of 8 institutions were prospectively enrolled and implanted with a custom 3D printed total talus replacement at both academic and private settings. Patients had demographics, range of motion (ROM), and PROMs collected preoperatively, at 6 weeks, 3 months, 6 months, and 12 months. PROMs included VAS pain score and Foot and ankle outcome score (FAOS). Adverse events were analyzed in patients with minimum 6 weeks of follow-up and the preoperative and follow-up PROMs for patients with minimum 6-month follow-up were analyzed. A total of 18 subjects (17 patients) were enrolled in the study, with all subjects reaching 6 weeks minimum follow-up and 10 patients achieving 6 months of follow-up. Results: The cohort was majority male (55.6%) with mean age 46.8±14.65 years and BMI 33.5±7.25 kg/m2. There were no adverse events related directly to the implant at 6-week follow-up. However, there were 2 serious adverse events (complications) documented, one case of wound dehiscence at 5 weeks postoperatively, and one deep wound infection at 2 weeks postoperatively. Subjects pain scores improved at 6 months postoperatively, with VAS scores statistically significantly decreasing (31.3 ± 31.83 points; p=.0222). All FAOS subscales showed significant improvement from preoperative to 6 months postoperatively with the greatest change coming in FAOS QOL (39.8 ± 28.06; p<.0001) followed by FAOS Pain (29.4 ± 25.13; p=.0004). (Table 1) Additionally, at 6 months postoperatively, 90% of patients indicated good or excellent satisfaction. Conclusion: Implementation of custom 3D printed total talus replacement was found to have low rates of short-term adverse events and proved to be safe and effective for the treatment of end stage avascular necrosis. Patients were largely satisfied at 6 months postoperatively and showed considerable [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: The overuse of opioid medications in patients undergoing orthopaedic surgery has become widely labeled as a national epidemic. Recent literature, particularly in the fields of orthopaedic spine surgery and joint arthroplasty, has illustrated an association between chronic opioid use and increased costs and postoperative complications. The purpose of this study is to evaluate the influence of chronic opioid dependence on postoperative outcomes following total ankle arthroplasty (TAA). We hypothesized that preoperative opioid dependence would be associated with higher rates of complications, revisions, readmissions, and mortality following TAA, as well as increased cost and longer hospital stays. Methods: The Nationwide Readmissions Database (NRD) was queried from 2015-2020 to identify 29,751 patients undergoing primary elective TAA. Patients were divided into two cohorts based on the presence of preoperative opioid dependence, with 861 (2.9%) being chronic opioid users or having opioid use disorders. Preoperative demographics, comorbidities, postoperative outcomes, cost of admission, and total length of stay (LOS) were analyzed between cohorts. Multivariate regression analyses were conducted to identify independent predictors of postoperative outcomes other than preoperative opioid dependence. Results: The overall cohort was majority male (54.2%) with mean age of 64.15 (range 17-90) years, and Charlson-Deyo Comorbidity Index (CCI) score of 0.65 (range 0-12). When stratifying by preoperative opioid dependence, it was found that opioid dependent patients were statistically significantly older (Opioid=62.74 years; Nonopioid=65.21 years; p<.001), from lower income quartile (p=.042), more likely to have Medicaid insurance (p<.001), and had a higher CCI score (Opioid=0.97; Nonopioid=0.64; p<.001). Multivariate regression analysis of 180-day postoperative outcomes found that preoperative opioid dependence was significantly predictive of increased risk of wound dehiscence (p<.001), adverse discharge (p<.001), and extended stay greater than 4 days (p<.001). Further, preoperative opioid dependence is predictive of more than a $1,000 increase in total cost of procedure (β= 1,052.27; 95% CI= 117.62-1,986.91; p=.027). (Table1) Conclusion: Chronic preoperative opioid use was significantly predictive of higher rates of postoperative complications, LOS, and a substantially higher cost of procedure following TAA. Physicians should consider this modifiable risk factor when identifying patients and tailoring medication regimens for patients receiving ankle arthroplasty. [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: Alcohol use disorder (AUD) has been estimated to affect approximately 11% of adults and is associated with increased morbidity, social consequences, and financial burden. A number of studies in orthopaedic spine and arthroplasty literature have indicated patients with preoperative AUD to be at increased risk for adverse outcomes, increased length of stay, and increased cost of procedure. However, there is a paucity of literature examining the effect of preoperative AUD on the outcomes of patients undergoing ankle arthrodesis (AA). The purpose of this study is to evaluate the influence of AUD on postoperative outcomes following AA. Methods: The Nationwide Readmissions Database (NRD) was queried from 2016-2020 to identify 26,705 patients undergoing primary elective AA as identified by International Classification of Diseases, Tenth Revisions (ICD-10), Procedure coding system (PCS) codes for ankle arthrodesis (OSGFXXX, OSGGXXX). Patients were divided into two cohorts based on the presence of preoperative alcohol use disorder, as identified by ICD-10 clinical modification (CM) codes, with 612 (2.29%) being diagnosed with AUD. Preoperative demographics, comorbidities, postoperative outcomes, cost of admission, and total length of stay (LOS) were analyzed between cohorts. Multivariate regression analyses were conducted to identify independent predictors of postoperative outcomes other than preoperative AUD. The overall cohort was majority male (51.0%) with mean age of 57.31±16.15 years, and Charlson-Deyo Comorbidity Index (CCI) score of 1.56±2.00. Results: Patients identified with preoperative AUD were statistically significantly younger (AUD=55.14 years; non-AUD=57.29 years; p<.001), male (AUD=75.3%, non-AUD=50.3%; p<.001), from the lowest income quartile (AUD=34.6%, non-AUD=27.3%; p<.001), more likely to have Medicaid insurance (AUD=30.7%, non-AUD=13.9%; p<.001), and had a significantly higher rate of multiple comorbidities, individually and as measured by CCI (AUD=2.07, non-AUD=1.55; p<.001). Multivariate regression analysis of 180-day postoperative outcomes found that preoperative AUD was significantly predictive of 22% increased risk of any complication (Odds ratio [OR]=1.217; p=.035), 42% increase in risk of readmission (OR=1.424; p<.001), and 135% increase in risk of extended LOS >4 days (OR=2.349; p<.001), among other specific complications listed in Table 1. Further, preoperative AUD is significantly predictive of nearly $7,000 increase in total cost of procedure (β=6,929.34; p<.001). Conclusion: Alcohol use disorder is associated with significantly increased perioperative morbidity in patients undergoing ankle arthrodesis. When controlling for differences in comorbid conditions, this study found preoperative AUD was significantly predictive of statistically significantly higher rates of postoperative complications, readmissions, and adverse discharge within 180-days of primary procedure as well as increased LOS, and a substantially higher cost of procedure following AA. Physicians should consider this risk factor when identifying patients and tailoring medication regimens for patients receiving ankle arthrodesis. [ABSTRACT FROM AUTHOR]

Category: Basic Sciences/Biologics; Diabetes Introduction/Purpose: Even with the best conservative care, patients with Charcot Neuroarthropathy (CN) of the foot and ankle often ulcerate, increasing their risk of infection, amputation, and death. Surgical fixation has a 30% risk of recurrent ulceration, likely due to poor host bone quality which is prone to deformity recurrence and subsequent ulceration. We propose midfoot beam reconstruction with PMMA augmentation as a novel means of improving fixation. Methods: A protocol was developed to create the characteristic CN midfoot fragmentation both visually and fluoroscopically in each of tweleve matched-pair cadaveric feet. Afterward, the pairs were divided into two groups (1) Midfoot beam fusion alone, and (2) Midfoot beam fusion augmented with PMMA. In both groups, a solid 7.0 mm beam was placed into the medial column and a solid, 5.5 mm beam was placed across the lateral column. In the PMMA group, 8-10 mL of PMMA was inserted into the medial column. The hindfoot of each specimen was potted and the metatarsal heads were cyclically loaded for 1800 cycles, followed by load to failure while load and displacement were continually recorded. Results: One specimen in the beam only group failed before reaching the 1800th cycle and therefore was not included in the failure analysis. The midfoot beam only group demonstrated greater mean displacement during cycle testing compared to the PMMA group, p< 0.05. The maximum force (N), stiffness (N/mm) and toughness (Nmm) were all significantly greater in group augmented with PMMA, p< 0.05. Conclusion: In a CN cadaveric model, PMMA augmentation significantly decreased gapping during cyclic loading and nearly doubled the load to failure compared to midfoot beams alone. Clinical Relevance: The results of this biomechanical study demonstrate that augmentation of midfoot beams with PMMA increases the strength and stiffness of the fusion construct, which may reduce the risk of nonunion and infection in patients with neuropathic midfoot collapse. [ABSTRACT FROM AUTHOR]

Category: Midfoot/Forefoot; Diabetes Introduction/Purpose: Charcot arthropathy is a debilitating and challenging clinical problem for patients and providers. Patient reported outcome measures (PROMs) are an effective tool for gauging a patient's quality of life and daily functioning but they have not been reported in the setting of midfoot Charcot arthropathy. Our goal is to assess PROMs severity in midfoot Charcot arthropathy (Brodsky Type 1), alongside linked demographics and comorbidities. We will compare these values with PROMs from conditions like ESRD, knee and hip arthritis, highlighting Charcot arthropathy's comparable debilitation. Methods: A retrospective chart review identified 67 patients with Brodsky Type 1 Charcot arthropathy by one of two fellowship-trained foot and ankle surgeons at a single academic medical center between years 2015 and 2023. ICD-10 CM codes E11.610, M14.671, and M14.672 were used to identify diagnosis of Charcot arthropathy and radiological interpretation determined Brodsky type. Data collected from patient charts included demographics, medical history, presence of ulcers, and preoperative Visual Analog Scale (VAS), 12-Item Short Form Health Survey (SF-12), Pain Catastrophizing Scale (PCS), Pain Disability Index (PDI), SSS-8, Foot and Ankle Outcome Score (FAOS), and Foot and Ankle Ability Measure (FAAM) scores and postoperative FAOS and FAAM scores. A One-Way ANOVA was performed to evaluate statistical significance. Averages of preoperative PROM scores were compared to literature values for other diseases. Results: Our cohort was mostly male (58.2%), with mean age 61.73 years, BMI 32.9, and A1C 6.9. Initial presentation revealed 50.7% had ulcers. Brodsky type 1 (midfoot) had notably the lowest pre-op PROM scores when compared to other Brodsky types: PDI Recreation (p=.033), FAOS Symptoms and Stiffness (p=.044), and FAOS Recreation (p=.027). Ulcer presence yielded significantly lower FAAM-ADL scores (p=.038), while other PROMs showed no statistical difference. Our mean VAS score was 53.34 which was higher than hip arthritis VAS (43.0) but lower than ESRD VAS (60.0) and knee arthritis VAS (64.2). Our SF-12 PCS scores (29.4) exceeded prior reports (hip 28.5, knee 28.6), while SF-12 MCS scores were higher in earlier studies (hip 49.6, knee 51.5) than our 43.8. Conclusion: Patients with Charcot arthropathy struggle in daily tasks, reflected in lowered FAOS ADL scores. Brodsky type 1 patients also face challenges in higher-level activities, evident in reduced PDI recreation and FAOS recreation scores. Those with ulcers similarly encounter issues in daily tasks, seen in lower FAAM ADL scores. Brodsky type 1 patients also experience debilitating pain as noted by higher VAS scores when compared to known debilitating conditions such as hip and knee arthritis. Comparatively minor differences in knee and hip arthritis SF-12 PCS scores indicate significant physical limitations for these patients. [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: Historically, a robust association between psychiatric conditions and perioperative complications following orthopaedic surgeries has been established. Within the past decade, the prevalence of total ankle arthroplasty (TAA) has risen by 136.1%. In a similar time frame, the United States has seen the prevalence of mental health disorders rise, a trend that was accentuated by the COVID-19 pandemic. This study aims to evaluate the effect of mental health disorders on the postoperative outcomes of patients undergoing primary TAA. Methods: The Nationwide Readmissions Database (NRD) was queried to identify 29,705 patients undergoing primary TAA from 2015 to 2020. Patients were then divided into cohorts based on concurrent mental health diagnosis (MHD) (MHD=6,041, no MHD=23,664). Further analysis was performed for common mental health diagnoses, including depression (n=3,553), anxiety (n=3,510), psychosis (n=592), bipolar disorder (BPD) (n=411), and post-traumatic stress disorder (PTSD) (n=235). A multivariate regression analysis was performed to control for confounding variables. Results: Patients with any MHD were significantly younger (p <.001), more likely to be female (p <.001), lower income (p <.001), and had a higher Charlson-Deyo Comorbidity Index (p <.001). These patients were also significantly more likely to have Medicaid insurance (p <.001) and be treated at an urban teaching hospital (p=.027). Patients with anxiety, depression, or psychosis experienced statistically significantly higher rates of complications. Similarly, patients with anxiety, psychosis, or PTSD experienced statistically significantly higher rates of postoperative deep infections. Multivariate regression analysis found any MHD to be predictive of increased risk of complication by 16% (OR=1.158; 95%CI=1.048-1.278; p=.004), adverse discharge by 70% (OR=1.678; 95%CI=1.57-1.793; p<.001), extended stay by 50% (OR=1.497; 95%CI=1.351-1.658; p<.001), and infection by 65% (OR=1.654; 95%CI=1.231-12.223; p<.001). Conclusion: Patients with MHD are at a statically significantly higher risk of complications, infections, protracted hospital stays, and adverse discharge outcomes following primary TAA. Careful appraisal and counseling are necessary in this patient demographic when considering patients selection for TAA. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Basic Sciences/Biologics Introduction/Purpose: Prolonged stresses at the bone/device interface can predispose patients to complications such as loosening or loss of compression in the setting of normal bone resorption during healing. In efforts to address these hardware failures, sustained dynamic compression (SDC) devices were developed, enabling the application of continuous compression in the setting of bone resorption or postoperative joint settling. However, the biomechanical performance of these SDC devices in subtalar arthrodesis constructs has not yet been explored. Thus, this study sought to compare the compression, capacity to adapt to resorption, and torsional stiffness of subtalar arthrodesis constructs utilizing either static or dynamic fixation in three clinically relevant screw trajectories (one device, two devices in parallel trajectories, two devices in diverging trajectories). Methods: Subtalar arthrodesis procedures were simulated on synthetic talus/calcaneus replicates (Sawbones) using two commercially available orthopedic fixation devices (Dynamic = 7.0mm dia. 90mm length, Static = 7.0mm dia; 90mm length, N=6/group) while bones were held in a custom fixture maintaining a gap (to enable simulated resorption). Constructs tested included: 1) single device posteriorly placed, 2) two devices with parallel trajectories, and 3) two devices with diverging trajectories (FigA). After inserting devices according to manufacturer specifications, initial compression and simulated resorption testing were performed (by moving bones into apposition while measuring interfragmentary compression), generating initial load and resorption capacity (resorption distance prior to loss of compression). A second set of simulated arthrodesis procedures were performed on samples that subsequently underwent inversion and eversion torsion testing, generating torsional stiffness values. Data were analyzed using a two-way ANOVA with Tukey post hoc test (α=.05; N=6 replicates/group). Results: Device trajectory (i.e., parallel vs. diverging) did not significantly impact the subtalar construct initial load(p≥0.90), resorption capacity (p≥0.78), or torsional stiffness (p≥0.50, FigB,C,D). The single dynamic device group exhibited significantly increased initial load (p < 0.001, FigB) and resorption capacity (p < 0.001, FigC) as compared to the single and double static device groups. Torsional stiffness was significantly increased in constructs that utilized two static devices as compared to those that used one static (p≤0.023, FigD). Across all constructs conformations (device quantity and trajectory), the dynamic device exhibited significantly increased torsional stiffness as compared to the static device (p=0.006, FigD). Conclusion: These findings demonstrate a notable enhancement in both initial load, resorption capacity, and torsional stiffness with the sustained dynamic compression device (Dynamic) compared to the Static group. Furthermore, the use of a single dynamic device provided significantly increased initial compression, significantly increased resorption capacity, and equivalent (not significantly different) torsional stiffness as compared to the N=2 static device constructs. Notably, device trajectory (diverging vs parallel) did not significantly alter the biomechanical properties of the arthrodesis construct. Thus, surgeons should consider the use of one or more dynamic devices in either trajectory when optimum biomechanical performance is desired. Dynamic Device Provides Increased Subtalar Arthrodesis Construct Compression and Resorption Capacity. A) Representative construct images depicting parallel and diverging device trajectories. B) Initial interfragmentary compression was significantly increased in all dynamic device constructs as compared to static device constructs. C) Resorption capacity was significantly greater in the constructs utilizing dynamic devices as compared to those that used static. D) Across all trajectory/quantity groups, the constructs utilizing dynamic devices displayed significantly increased torsional stiffness as compared to those that used static devices. [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: As the incidence of TAA increases, identifying ways to stratify a patient's risk for adverse outcomes becomes imperative. Two potential tools, the Charlson Comorbidity Index (CCI) and Elixhauser Comorbidity Index (ECI), have been widely supported and utilized across various fields of medicine and orthopaedic surgery. Despite encouraging results in TAA literature, the validity of the CCI and ECI as predictive tools for postoperative complications and functional outcomes following TAA remains ultimately unexplored. This study aims to describe and compare the predictive capacity of the CCI and ECM on the outcomes of TAA to further understand the reliability of such comorbidity indices in orthopaedic research. Methods: The Nationwide Readmissions Database (NRD) was queried from 2015 to 2020 to identify 29,705 patients undergoing primary TAA. Patients' comorbidity was measured via CCI and ECI score, with patients who experienced adverse postoperative outcomes (any complication, readmission, mortality, extended length of stay (LOS), and adverse discharge) identified. Each index's predictive ability was measured using the c statistic, a measure of area under the receiver operating characteristic curve (AUC). The value for AUC ranges from 0.50 to 1.0, indicating the discriminative ability of each index in assigning probability of the examined outcome, with 0.50 indicating no ability to discriminate and 1.0 indicating perfect ability to discriminate. AUC was categorized into poor (AUC<.70), acceptable (0.70< AUC< 0.80), excellent (0.80< AUC< 0.90), and outstanding (0.90< AUC< 1.0) regarding the predictive capability of each model. The indices were also compared to a base model, which considered age, sex, and primary payer. Results: The overall cohort was majority male (54.2%) with a mean age of 64.15 (range 17-90) years, and the majority of patients had Medicare as their primary expected payer (58.9%). Elixhauser comorbidity index provided a superior predictive ability for any complication (ECI AUC=0.61, CCI AUC=0.59; p<.001), extended LOS (ECI AUC=0.69, CCI AUC=0.65; p<.001), and adverse discharge (ECI AUC=0.70, CCI AUC=0.68; p<.001) as compared to the Charlson comorbidity index. Examination of each model's predictive ability found mortality was the only variable that both ECI (AUC=0.88, 95%Confidence Interval [CI]= 0.77–1.00) and CCI (AUC=0.88; 95% CI=0.79–0.96) were able to predict with excellent capability. Additionally, the ECI predicted adverse discharge with acceptable capability (AUC=0.70; 95%CI=0.69-0.71). Conclusion: In this study, the ECI outperformed the CCI in predicting any complication, extended length of stay ≥4 days, and adverse discharge to a facility in patients undergoing total ankle arthroplasty. However, the only variable that was excellently predicted was 180-day mortality, in which there was no difference in the predictive capability of each index. These findings indicate that while ECI and CCI are capable of predicting postoperative mortality following TAA, there is a need for alternative models that offer better predictive capability when examining other postoperative adverse outcomes. [ABSTRACT FROM AUTHOR]

Category: Trauma; Ankle Introduction/Purpose: Ankle fractures are among the most common injuries in orthopaedics and often require surgical management to obtain a stable mortice. It is essential to quantify preoperative risk for patients undergoing ankle fracture repair, but a consensus regarding an optimal risk stratification model does not currently exist. The 5-factor modified frailty index (mFI-5) has been found to be an independent predictor of postoperative complications following numerous orthopaedic procedures, but its efficacy has not been evaluated in patients undergoing ankle fracture open reduction and internal fixation (ORIF). This study aims to analyze the effect of preoperative mFI-5 on 30-day complication, readmission, reoperation, and mortality rates following ankle fracture procedures. Methods: The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database was queried from 2005-2019 to identify 44,755 patients undergoing ankle fracture ORIF using Current Procedural Terminology (CPT) codes 27766, 27792, 27814, 27822, and 27823. Patients were stratified into groups based on preoperative mFI-5 scores, which incorporate the presence of chronic obstructive pulmonary disease, pneumonia, congestive heart failure, non-independent functional status, and diabetes into a composite risk index. Demographics, hospital length of stay (LOS), and 30-day complication, surgical site infection (SSI), Clavien-Dindo grade IV (CDIV) complication, readmission, reoperation, and mortality rates were compared between groups. The cohort was predominantly male (59.0%) and the mean age was 49.52 (range, 16-89) years. Preoperative mFI-5 was also used as a categorical variable when analyzing postoperative outcomes. Results: A total of 44,838 patients met criteria for inclusion, with the majority of patients having an mFI-5 score of 0 (mFI-5:0=65.1%, mFI-5:1=27.0%, mFI-5:2=6.5%, mFI-5:3=1.1%, mFI-5:4=0.2%). The mFI-5 score was a predictor of serious medical complications (myocardial infarction, sepsis, pulmonary embolism, postoperative dialysis, prolonged ventilator requirement, SSI, blood transfusion, DVT/thrombophlebitis, and pneumonia), adverse discharge to a facility, readmission, and reoperation. (Table 1) Mortality was strongly predicted by mFI-5 with the risk more than tripling for each point increase in mFI-5 score (odds ratio (OR)=3.639, 95% CI= 3.038-4.360). Lastly, LOS was also found to increase with mFI-5 with the average length of stay increasing by 1.44 days per increase in mFI-5 score. Conclusion: Our results indicate that mFI-5 score is useful as a predictive measure for postoperative complications, adverse discharge, readmission, reoperation, mortality, and length of stay for patients undergoing ankle ORIF. The variables considered by mFI-5 are easily obtained through a patient history, making this scale a practical measure to identify patients at increased risk for postoperative outcomes. [ABSTRACT FROM AUTHOR]

Category: Ankle Arthritis; Ankle Introduction/Purpose: The Kellgren-Lawrence scale has been used as a valid and reliable system to grade osteoarthritis. This study seeks to examine the association between preoperative Kellgren-Lawrence (KL) scale grade of ankle or hindfoot arthritis and postoperative outcome measures (PROMs) in patients undergoing total ankle arthroplasty (TAA), ankle arthrodesis (AA), or hindfoot arthrodesis. Methods: A retrospective review was conducted of 254 ankles (250 patients) with minimum 6-month follow-up, undergoing TAA, AA, or hindfoot arthrodesis from 2016-2022. Patients were identified by having undergone surgery via CPT codes (27702, 27870, 27815, or 27825). 131 patients (51.6%) underwent TAA. Of patients undergoing various ankle and hindfoot fusions, involved joints were tibio-talar (n=83; 32.7%), sub-talar (n=46; 18.1%), talo-navicular (n=15; 5.9%) and calcaneocuboid 1 (0.3%). Preoperative KL grade of the joint undergoing arthrodesis/arthroplasty was evaluated. Data collected included demographics, medical history, PROMs (FAOS, FAAM, VAS, SSS-8, PDI, and PCS), postoperative complications, readmission and reoperation rates. The final cohort mean age was 58.26 (range 18-85) years with mean BMI 31.97 (range 17.85-61.38) kg/m2 and mean follow-up of 1.69 (range 0.50-6.13) years. Results: The overall cohort was primarily KL grade 3 and 4 at each of the examined joints. There were no significant differences in demographics or procedure performed between groups, with the exception of age, which was statistically significantly associated with an increased KL grade for the TN joint (p=.006). Preoperatively, the tibiotalar joints with a KL grade of 3 were associated with significantly higher preoperative SSS-8 scores (p=.002). A preoperative KL grade of 2 at the subtalar joint was associated with significantly lower preoperative FAOS recreation scores (p=.030). Postoperatively, there was no statistically significant difference in patient reported outcomes with any of the examined joints KL grade. Lastly, there was no statistically significant association between KL score of any joint and postoperative complication, readmission, or reoperation. Conclusion: There was no association between preoperative Kellgren-Lawrence grade and post-operative PROMs or mean 1.69 year outcomes following TAA, AA, or hindfoot arthrodesis. Surgeons should be aware that, at least for patients indicated for TAA or ankle/hindfoot arthrodesis, preoperative KL grade does not seem to impact short term PROM scores. [ABSTRACT FROM AUTHOR]

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Plantar fasciitis is one of the most common causes of foot pain among the United States' population. There are several treatment options including both nonoperative and operative approaches. Recently, minimally invasive (MIS) percutaneous plantar fasciotomy has come on the market with anecdotally good patient outcomes but limited published literature. This study aimed to review the patient outcomes, complications, and revision rates in patients undergoing MIS ultrasound-guided percutaneous plantar fasciotomy for the treatment of chronic plantar fasciitis. Methods: A multicenter retrospective chart review of patients undergoing MIS ultrasound-guided percutaneous fasciotomy using the Tenex device (Trice Medical, Lake Forest California) from January 2020 to December 2022 was performed. The main data points collected were patient-reported outcomes, follow-up times, revision surgery, and complications. Continuous variables were defined as a mean and were compared using Paired Student's T-Test. Multivariable linear regression analysis was utilized to determine specific factors that influenced outcomes when controlling for confounding variables. All P< 0.05 were considered significant. Results: There were 56 (42 female/14 male) patients that underwent 60 procedures. The average age and BMI were 48.6 years (range 19–80), and 33.2 kg/m2 (range 19.7–58.6), respectively. There were two (3.3%) complications of wound-healing delays and one (1.7%) complication of nerve damage noted. There were two (3.3%) revisions. The average follow-up was 27 months (range 13.3–48.6). The average improvement in pain, physical function, and mobility Patient-Reported Outcomes Measurement Information System (PROMIS) scores were 5.2 (range: -5.1–25.8), P< 0.01), 3.6 (range -7–30.7, P=0.01), and 3.1 (range -6–25, P=0.01). Overall, over 90% of patients had no to minimal pain at the final follow-up. No specific demographic factors were significantly associated with an improvement in PROMIS scores or overall pain at final follow-up. Conclusion: MIS ultrasound-guided plantar fasciotomy appears to be a reliable surgical treatment option for chronic plantar fasciitis with high patient satisfaction, minimal complications, and low revision rates. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Ankle Introduction/Purpose: Tibiotalocalcaneal (TTC) arthrodesis is commonly performed for complex deformity, arthritis, or unstable Charcot about the hindfoot. Due to this complexity, these procedures are often associated with increased morbidity and postoperative complications. There is limited data analyzing the prevalence of various preoperative diagnoses and comorbidities, as well as treatment modalities on the outcomes of TTC arthrodesis. As such, this study aims to investigate how various preoperative and intraoperative factors affect the outcomes of patients undergoing TTC arthrodesis. Methods: A multi-center retrospective review was conducted on the TTC fusions performed from 2016-2023 by one of four fellowship trained foot and ankle surgeon at an academic medical center. 74 ankles (75 patients) underwent TTC arthrodesis. Preoperative diagnosis and indications, fixation method, clinical success, and complications were obtained from the patients' charts. Surgical indications included arthritis (n=39), Charcot neuropathy (n=23), post-traumatic (n=14), and cavovarus (n=10), osteomyelitis (n=4), and foot drop (n=3). Patients were excluded if their clinical or radiographic data were unavailable for review, or if they had less than 6 months of follow-up. Mean age was 58.2 (range 31-81) years and mean follow-up was 1.7 (range.50-5.17) years. Statistical analysis was performed using t-Student and Chi-squared tests with a p-value of 0.05 defining significance. Midline tibiotalar angle (MTA) was measured before and after surgery to assess position of fusion. Thirteen patients had preoperative ulcers at the time of surgery. Results: The most common surgical approach was lateral (n=47), then anterior (n=21) and posterior (n=7). Patients undergoing a lateral and posterior approach had statistically significantly higher rates of overall postoperative complication (lateral=51.1%, posterior=57.1%, anterior=19.0%; p=.029), although this was not specific to any single complication. Patients undergoing concomitant fibular osteotomy (n=41, 55%) experienced significantly higher rates of postoperative complications (osteotomy=61.0%, no osteotomy=21.2%; p<.001). Multivariate backward stepwise regression analysis on the occurrence of overall postoperative complications was performed to control for preoperative and intraoperative factors, finding that only concomitant fibular osteotomy was associated with increased risk of postoperative complication (odds ratio [OR]=7.494; p=.009). Conclusion: TTC arthrodesis continues to have high rates of postoperative complications and adverse outcomes. The present study found increase rates of complication in patients receiving TTC via a lateral approach, patients receiving a plate construction, and patients undergoing concomitant fibular osteotomy. Multivariate regression analysis found only concomitant fibular osteotomy to statistically significantly independently predict postoperative complication. Further studies with larger sample size are needed to confirm these findings and further identify factors which place patients at increased risk for adverse postoperative complications. [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: Recent literature has indicated higher body mass index (BMI) to be of concern for poorer outcomes following total ankle arthroplasty. The purpose of this study is to evaluate the impact of implementing BMI cutoff points on 6-month postoperative outcomes following total ankle arthroplasty (TAA). Methods: The Nationwide Readmissions Database (NRD) was queried from 2015-2020 to identify 5,865 patients undergoing primary elective TAA with a reported BMI range via ICD-10 diagnosis. Our cohort consisted of patients with BMI ≥30 kg/m2, stratified into groups by 5 BMI point intervals. Preoperative demographics, comorbidities, postoperative outcomes, and total length of stay (LOS) were analyzed between cohorts. Multivariate regression analyses were conducted to control for predictors of adverse postoperative outcomes other than BMI. Results: When stratifying by preoperative BMI, higher BMI was associated with significantly lower age (p <.001) and rate of smoking (p <.001), and higher rate of female sex (p <.001), Medicaid insurance (p <.001), higher CCI score (p <.001), among other comorbidities. Multivariate regression analysis of 180-day postoperative outcomes, controlling for demographic and comorbidity differences, found that preoperative BMI 40-44.9 and ≥45 kg/m2 was significantly predictive of increased risk of any complication (44-44.9: OR=1.843; p<.001)(45+: OR=1.960; p<.001), adverse discharge (44-44.9: OR=1.217 p=.015)(45+: OR=2.030; p<.001), and extended stay greater than 4 days (44-44.9: OR=1.653; p<.001)(45+: OR=2.171; p<.001), with BMI ≥45 kg/m2 also being significantly predictive of 65% increased risk of readmission (OR=1.655; p=.004). Conclusion: Higher BMI in TAA is associated with an increased risk of any postoperative complication, adverse discharge, and extended LOS. Specifically, a BMI cutoff of 40kg/m2 would serve to prevent 38.6% of the 963 obese patients experiencing complications following TAA. While our results suggest that implementing a strict BMI cutoff would serve to reduce complications substantially, it will also prevent a large number of patients from undergoing a complication-free surgery that will ultimately serve to reduce pain and increase function. Instead, we suggest physicians consider a BMI cutoff in concert with other comorbidity factors that may affect surgical outcomes following TAA. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Ankle Introduction/Purpose: Tibiotalocalcaneal (TTC) arthrodesis is commonly performed for complex deformity, arthritis, or unstable Charcot about the hindfoot. Due to this complexity, these procedures are often associated with increased morbidity and postoperative complications. There is limited data analyzing the prevalence of various preoperative diagnoses and comorbidities, as well as treatment modalities on the outcomes of TTC arthrodesis. As such, this study aims to investigate how various preoperative and intraoperative factors affect the outcomes of patients undergoing TTC arthrodesis. Methods: A multi-center retrospective review was conducted on the TTC fusions performed from 2016-2023 by one of four fellowship trained foot and ankle surgeon at an academic medical center. 74 ankles (75 patients) underwent TTC arthrodesis. Preoperative diagnosis and indications, fixation method, clinical success, and complications were obtained from the patients' charts. Surgical indications included arthritis (n=39), Charcot neuropathy (n=23), post-traumatic (n=14), and cavovarus (n=10), osteomyelitis (n=4), and foot drop (n=3). Patients were excluded if their clinical or radiographic data were unavailable for review, or if they had less than 6 months of follow-up. Mean age was 58.2 (range 31-81) years and mean follow-up was 1.7 (range.50-5.17) years. Statistical analysis was performed using t-Student and Chi-squared tests with a p-value of 0.05 defining significance. Midline tibiotalar angle (MTA) was measured before and after surgery to assess position of fusion. Thirteen (17.3%) patients had preoperative ulcers at the time of surgery. Results: Of the 74 subjects in the study, 32 (43.2%) experienced postoperative complications, 14 (18.9%) had postoperative infection, 17 (23.0%) underwent reoperation for hardware removal, 10 (13.5%) experienced wound breakdown, 8 (10.8%) experienced nonunion, and 4 (5.4%) underwent below knee amputation. There was no statistical association between any surgical indication and adverse postoperative outcome, including patients with Charcot neuropathy. Majority of patients received a TTC nail (n=68, 94.4%) as opposed to plate (n=4; 5.6%), with plate configurations experiencing higher rates of overall complication (plate=100%, nail=39.7%; p=.031) and hardware removal (plate=75%, nail=20.6%; p=.039). There was no statistically significant difference in rates of any adverse outcomes when stratifying by use of combined external fixation and internal fixation (n=12;16.7%), 3D printed cage implant (n=7;9.5%), or use of graft (n=63;85.1%). Conclusion: TTC arthrodesis continues to have high rates of postoperative complications and adverse outcomes. The present study found increase rates of complication in patients receiving patients receiving a plate construction. There was no difference in rates of adverse outcomes when considering preoperative indication, including Charcot neuropathy, nor use of graft, 3D printed cage, or both external and internal fixation. Further studies with larger sample size are needed to confirm these findings and further identify factors which place patients at increased risk for adverse postoperative complications. [ABSTRACT FROM AUTHOR]

Category: Ankle; Ankle Arthritis Introduction/Purpose: Osseointegration is an important determinant of clinical success following the insertion of a orthopaedic implants. The success of osseointegration is an important predictor of the long-term clinical success of many implants, especially total joint arthroplasties. Total ankle arthroplasty (TAA) is a common surgical treatment for patients with end-stage ankle osteoarthritis. Aseptic loosening is a common complication following TAA and may be related to poor osseointegration between the prosthesis and the host bone. Thus, the purpose of this study is to investigate the patterns of ingrowth and ongrowth bone formation that occur following implantation with in Inbone TAA, and the correlation of those with patient outcomes. Methods: We conducted a retrospective review of eleven patients that underwent primary (n=8) or revision (n=3) total ankle arthroplasty with a single fixed bearing stemmed total ankle implant for end stage ankle arthritis. All participants underwent surgery at a single academic medical center with one of two foot and ankle fellowship trained surgeons. Data was collected from medical charts and imaging software. Radiographic measurements were performed on both weightbearing preoperative and postoperative radiographs and non-weightbearing CT scans. The cohort was majority male (72.7%%), with mean age 62.42 (range 40.54-81.00) years, and mean radiographic follow-up of 1.95 (range 0.46-10.39) years. Of the eleven subjects, ten had preoperative cysts on the tibia and talus. Three of the subjects exhibited new cyst formation post-implantation, notably including the patient who had no preoperative cysts. Results: Following implantation, four patients underwent reoperation, but none required revision. Cyst size and location did not significantly affect reoperation rates or alignment measurements. At 2-years postoperatively, increased radiolucency at the 2nd or 4th quadrants of the tibial stem tip was correlated with more valgus tibiotalar angle (r=.960: p=.010), while increased radiolucency in the 1st quadrant of the tibial stem shaft was correlated with a more valgus tibiotalar angle (r=-.960; p=.010). Increased radiolucency at the 3rd quadrant of the tibial stem tip (r=.957: p=.011), and 1st (r=.926: p=.024) or 2nd (r=.915: p=.029) region of the tibial stem base were correlated with a more valgus coronal tibial angle. Increased radiolucency at the 2nd quadrant of the tibial stem shaft was associated with greater sagittal displacement (r=-.926, p=.024). Conclusion: Our results demonstrate that the TAA outcomes were not affected by preoperative cyst presence nor postoperative cyst presence, region, or size. There were, however, a number of radiographic alignment measurements affected by radiolucency around the implant at 1 and 2 years postoperatively. Given the rapidly expanding implementation of TAA and the relatively high revision rate following the procedure, extensive research should be conducted to determine if osseointegration affects desirable patient outcomes. [ABSTRACT FROM AUTHOR]

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: A 1st Tarsometatarsal (TMT) fusion or Lapidus is increasingly popular for moderate to severe hallux valgus with pronation. Hardware utilized for fixation consists of different combinations of plates, screws, and staples. Prior studies have suggested that constructs including a plate are superior to those consisting of screws or staples only. This biomechanical report compares a novel 1st TMT fusion U-plate to a predicate biplanar locking plating system. Methods: A total of 7 TMT U-plate systems were utilized for mechanical testing, with 3 samples undergoing static testing and 4 samples undergoing dynamic testing. Their mechanical properties were compared to those of one predicate device for static testing and 4 devices for dynamic testing. Standard 4th generation Sawbones models and bicortical screws were utilized in all cases. Static testing consisted of a uniform ramp to catastrophic failure using a cantilever bending model. Dynamic testing consisted of an incremental step procedure. A step size of 50,000 cycles at 3 Hz was used. The peak tensile load defined the step size with the valley tensile loading at one-tenth the peak loading. The first step used a 3.6 Nm moment with a peak tensile loading at 120 N. Results: Static testing of the TMT U-plate system demonstrated comparable or superior performance in load to failure testing than the predicate device (U-plate: mean = 351.3N, SD = 29.6; predicate: 324.4N). Dynamic testing demonstrated that the U-plate system survived 76,602 ± 43,275 cycles which was 261% greater than tested predicate constructs 29,338 ± 33,080 cycles. Additionally, cyclic failure loads were 151.3 ± 23.9 N for the U-plating system which was 120% greater than the predicate constructs at 126.3 ± 12.5 N. Conclusion: The TMT U-Plate demonstrated superior or comparable biomechanical properties to the predicate device in static and dynamic mechanical testing. Further investigation is needed to ascertain if these biomechanical differences have clinical correlations. [ABSTRACT FROM AUTHOR]

Category: Ankle Arthritis; Other Introduction/Purpose: Fourth-generation total ankle prostheses are evolving to address common complications following total ankle replacement, one of which is aseptic talar component loosening. A chamfered cut talar dome component, requiring less bone resection than flat cut components, is commonly used. Alternatively, a flat cut talar dome component with a larger talar "peg" has been suggested to increase bone-implant interface and stability. To date, there is limited reported data concerning survivorship and clinical improvement following the use of these two interchangeable talar dome components with the same tibial replacement component. The purpose of this study is report on prospectively collected patient reported outcome measures (PROMs) and clinical outcomes in a multi-institutional study of a fourth-generation total ankle with either flat or chamfer cut talar implant. Methods: Patients presenting for a total ankle replacement at 12 institutions were prospectively enrolled and implanted in both academic and private settings. Patients were implanted with a single low profile tibial implant and one of two interchangeable talar components, either a flat cut component with a talar stem and anterior fixation pegs or chamfered cut with anterior fixation pegs. At two year follow-up, 132 subjects were studied, 89 (67.4%) were implanted with a chamfered cut talar component and 43 (32.5%) with flat cut component. Patients had demographics, adverse events, and PROMs recorded pre-operatively and at 6, 12, and 24-month intervals. The following PROMs were collected: Ankle Osteoarthritis Score (AOS), PROMIS Global Physical Health, Foot and Ankle Outcome Score (FAOS), and satisfaction scores. The preoperative and latest follow-up scores for patients with minimum two years of follow-up were analyzed. Results: The overall cohort (54.7% male) had an average age of 64.2 ± 9.39 years old with an average BMI of 31.0 ± 5.17. Regardless of talar component, patients improved significantly in all PROMs domains at two years, including: Mean Total AOS (Chamfered: 19.1 ± 20.0, p<.0001; Flat: 16.8 ± 14.9, p<.001); PROMIS Global Physical Health (Chamfered: 8.83 ± 7.63, p<.0001; Flat: 8.56 ± 8.21, p<.001); Total FAOS Score (Chamfered: 38.1 ± 20.7, p<.0001; Flat: 40.2 ± 20.8, p<.001). There was no significant difference in the change in PROMs between talar components. At 2-years, 5 (4.9%) patients who received the chamfer cut component experienced device-related adverse events. None of the patients who received the flat cut talar component experienced such events or required revision surgery. Conclusion: At two-years post-implantation follow-up, the fourth-generation total ankle replacement with flat cut component had a low revision rate and proved to be safe and effective compared to historical ankle replacement outcomes. Patients had statistically significant clinical improvements in each domain of their PROMs, with there being no difference between the two talar components. [ABSTRACT FROM AUTHOR]