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Background: Ankle fracture surgeries are generally safe and effective procedures; however, as quality-based reimbursement models are increasingly affected by postoperative readmission, we aimed to determine the causes and risk factors for readmission following ankle fracture surgery. Methods: Ankle fracture cases were identified from the prospectively collected American College of Surgeons National Surgical Quality Improvement Program from 2013 to 2014. Demographics, comorbidities, and fracture characteristics were collected. Rates of 30-day adverse events and readmissions were determined as well as the causes for readmission. Multivariable logistic regression analyses were performed to identify risk factors associated with having any adverse events and being readmitted within 30 days of surgery. Results: There were 5056 patients included; 167 (3.3%) were open fractures. The rate of any postoperative adverse event was 5.2%. There were 116 unplanned readmissions, with a readmission rate of 2.3%. Of the 116 unplanned readmissions, 49 (42.2%) were for reasons related to the surgery or surgical site, with the most common causes being deep surgical site/hardware infections (12.9%), superficial site infections (11.2%), and wound disruption (6.9%). Most readmissions were for reasons unrelated to the surgical site (51.7%), including cardiac disorders (8.6%), pulmonary disorders (7.8%), and neurological/psychiatric disorders (6.9%). The cause of readmission was unknown for 6% of readmissions. With multivariable logistic regression, the strongest risk factors for readmission were a history of pulmonary disease (odds ratio [OR], 2.29), American Society of Anesthesiologists (ASA) class ≥3 (OR, 2.28), and open fractures (OR, 2.04) (all P < .05). Conclusion: In this cohort of 5056 ankle fracture cases, 2.3% of patients were readmitted within 30 days, with at least 51.7% of all unplanned readmissions due to causes unrelated to the surgery or surgical site. Predictors of readmission included a history of pulmonary disease, higher ASA class, and open fractures. Based on these findings, we advocate close medical follow-up with nonorthopaedic providers after discharge for high-risk patients. Level of Evidence: Level III.

Category: Ankle; Ankle Arthritis Introduction/Purpose: Prior studies on the INBONE II and Salto Talaris total ankle arthroplasty (TAA) systems have reported favorable outcomes for both implants. However, it is unclear whether there were significant differences in survivorship between and if this led to subsequent differences in clinical or radiographic outcomes the two. To date, no similar comparisons have been done in the literature, although it is important to understand the clinically relevant distinctions between these more recent third generation TAA systems. This retrospective study aimed to compare the midterm differences between INBONE II and Salto Talaris TAA. Methods: Between 2007 and 2015, 44 INBONE II consecutive cases and 85 Salto Talaris consecutive cases had minimum 5-year clinical and radiographic follow-up. The endpoints for survivorship were revision, defined as removal or replacement of any implant component, and reoperation, defined as a non-revision surgery. Preoperative and midterm postoperative Foot and Ankle Outcome Score (FAOS), which has been validated for ankle osteoarthritis, and radiographic measures including tibiotalar alignment (TTA) and medial distal tibial angle (MDTA) were compared. Talar inclination angle (TIA) was compared to examine subsidence and cysts were examined for osteolysis. Average midterm follow-up for these patients was 6.4 +- 1.1 (range, 5-9) years for the INBONE II group, and 7 +- 1.9 (range, 5-12.7) years for the Salto Talaris group. Results: Survivorship to revision was 97.6% (95% CI, 93.1%-100%) for the INBONE II group and 97% (95% CI, 93%-100%) for the Salto Talaris group (P = .93). Survivorship to reoperation was significantly different; 95.5% for the INBONE II and 76.4% for Salto Talaris (P = .021) (Figure 1). All FAOS improved postoperatively (P < .001), although the INBONE II had superior postoperative scores in pain (P = .01), symptoms (P = .004), and sports activity (P = .02). There were no differences between groups in postoperative radiographic alignment, despite the INBONE group having greater preoperative deformity. There was one instance of subsidence in each group and similar rates of cyst occurrence across the INBONE II (18.2%) and Salto Talaris (21.2%) groups. Conclusion: Although both implants had similar longevity and postoperative alignment, the INBONE II resulted in greater clinical improvement and fewer reoperations than the Salto Talaris at midterm follow-up. The majority of reoperations in the Salto Talaris group were due to gutter impingement. The contrasting reoperation rates between groups may be explained by differences in implant design and technique, such as rotational malpositioning of the talus and the lateral sulcus design of the Salto Talaris. Additionally, the INBONE II TAA system was able to correct deformity and improve clinical outcomes even though this cohort exhibited greater preoperative deformity.

Category: Ankle; Ankle Arthritis; Hindfoot; Midfoot/Forefoot; Other Introduction/Purpose: Subtalar fusion is a powerful option for correcting hindfoot deformity in progressive collapsing foot deformity (PCFD). Despite successful correction through subtalar fusion, the development of valgus tibiotalar tilt at the ankle joint has been documented as a significant complication. This can be detrimental since abnormal forces on the ankle joint can induce cartilage wear and subsequent ankle arthritis over time. However, the incidence of valgus tilt of the ankle following subtalar fusion for PCFD reconstruction has not been extensively studied, and little is known about its etiological factors. The purpose of this study was to define the incidence of valgus tibiotalar tilt after subtalar fusion for PCFD reconstruction, and to determine if any demographic and radiographic parameters predict which patients develop this complication. Methods: This study reviewed 59 patients (median age: 59 years) who underwent PCFD reconstruction with subtalar fusion and had pre-and postoperative weightbearing anteroposterior radiographs of the ankle in the registry. Patients with a tibiotalar tilt prior to surgery were excluded. On standard weightbearing radiographs, the talonavicular coverage angle, talo-1st metatarsal angle, calcaneal pitch, and hindfoot moment arm (HMA), and medial distal tibial angle were measured. Weightbearing computed tomography (WBCT) was used to determine the presence of preoperative sinus tarsi or calcaneofibular bony impingement. A radiologist evaluated the superficial and deep deltoid ligaments using magnetic resonance imaging (MRI). Postoperative valgus tibiotalar tilt was defined as tilt >2 degrees. Univariate regression analysis was used to identify the factors associated with development of postoperative valgus tibiotalar tilt. These factors included age, gender, BMI, as well as concomitant procedures, radiographic parameters, lateral bony impingement on WBCT, and deltoid ligament status on MRI. Results: A total of 17 patients (28.8%) developed postoperative valgus tibiotalar tilt at a mean of 7.7 (range, 2-31) months. Eight (47.1%) of the 17 patients developed valgus tibiotalar tilt (mean talar tilt of 5.3 degrees, range: 4-8) on postoperative weightbearing within 3 months. In bivariate analysis, male gender and preoperative HMA were significantly associated with development of valgus tibiotalar tilt (Table 1). Univariate logistic regression demonstrated that preoperative HMA was associated with postoperative valgus tibiotalar tilt (odds ratio 1.06, P = .026), with a 6% increase in risk per millimeter of increased HMA. Deltoid ligament status on MRI and concomitant procedures on other joints including fusion did not correlate with postoperative valgus tibiotalar tilt. Conclusion: The incidence of valgus tibiotalar tilt after subtalar fusion in PCFD reconstruction was 28.8% in this study. Preoperative valgus hindfoot alignment rather than the condition of the deltoid ligament was a significant predictor of postoperative valgus tibiotalar tilt. Our findings indicate that surgeons should be cognizant of patients with a greater degree of hindfoot valgus and of their propensity to develop a valgus ankle deformity. Additionally, our relatively high incidence of valgus tibiotalar tilt suggests that weightbearing ankle radiographs should be included in the initial and subsequent follow-up of PCFD patients with hindfoot valgus treated with subtalar fusions.

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Lateral bony impingement, one of the main causes of lateral foot pain in progressive collapsing foot deformity (PCFD), reflects disease severity and may affect surgical planning. Weightbearing computed tomography (WBCT) is known to provide better sensitivity in detecting impingement over simple radiographs, however, many Orthopaedic centers have not yet acquired WBCT imaging. This study aimed to (1) investigate the correlation of common radiographic parameters measured on standard weightbearing radiographs with talocalcaneal and calcaneofibular distance assessed with WBCT and (2) establish cut-off values for radiographic measurements on standard radiographs to detect lateral bony impingement as identified on WBCT. Methods: Ninety-one adult patients (mean age and standard deviation, 54.1 +- 17.2 years) treated for PCFD with standard preoperative radiographs and WBCT within 6 months of each other were retrospectively identified. Patients with previous ipsilateral foot and ankle surgery or asymmetric ankle arthritis (talar tilt > 2 degrees) were excluded. The talocalcaneal distance at the sinus tarsi and subfibular calcaneofibular distance were measured in multiplanar reconstructed WBCT images. Bony impingement was defined as direct contact between the structures. The relationships between WBCT measurements and four common parameters (Talonavicular coverage angle [TNC], Talo-1st metatarsal angle, Calcaneal pitch, and hindfoot moment arm [HMA]) in standard radiographs were assessed with Pearson correlations. Receiver operating characteristic (ROC) curve analysis was performed to determine the ability of radiographic parameter thresholds to predict sinus tarsi or calcaneofibular bony impingement, and the area under curve (AUC), sensitivity, specificity, negative and positive predictive value were calculated. Results: Talocalcaneal distance narrowing at the sinus tarsi on WBCT was strongly correlated with TNC (r = 0.64, p < 0.001), and the calcaneofibular distance narrowing on WBCT correlated with the HMA moderately yet best among the parameters (r=0.55, p

Category: Ankle Arthritis; Ankle Introduction/Purpose: A relatively frequent need for secondary surgery is an important consideration when treating end-stage ankle arthritis with total ankle arthroplasty (TAA). Despite a significant reported rate of non-revision reoperation after TAA, it is uncertain if these subsequent procedures have an impact on the longer term outcomes. It is imperative to know whether patients undergoing reoperation after TAA would have comparable functional ability compared to those with uncomplicated TAA in order to optimize patient outcomes when faced with complications after TAA. This study aimed to compare minimum five-year functional outcomes of patients who had undergone reoperation after TAA to those who did not require reoperation. Methods: Seventy-six ankles (74 patients) who underwent TAA with the Salto Talaris fixed bearing system between 2007 to 2014 were allocated into two groups based on presence (n=16) or absence of reoperation (n=60). Reoperations included all secondary procedures after index TAA, excluding revision surgeries requiring removal or exchange of the original prosthesis. The foot and ankle outcome score (FAOS) at preoperative and minimum five-year follow-up was compared between the groups. Additionally, improvements in FAOS subscales were compared. Preoperative deformity, postoperative implant alignment, number of periprosthetic cysts, and subsidence between groups were compared using standard weightbearing radiographs. A subgroup analysis was performed to compare clinical and radiographic outcomes of gutter impingement patients to those of uncomplicated group. Results: The most common cause of reoperation was gutter impingement (n=11), followed by stress fracture of the medial malleolus (n=2), tarsal tunnel syndrome (n=1), periprosthetic cyst (n=1), and infection (n=1). In comparison to the non- reoperation group, all FAOS subscales except for the Sports and Recreational Activities subscale were significantly lower in the reoperation group at final follow-up. The reoperation group exhibited significantly less improvement in the Pain, Symptoms, and Quality of Life subscales at final follow-up (p

Category: Ankle Arthritis; Ankle; Other Introduction/Purpose: The Cadence Total Ankle System (Smith and Nephew, Memphis, TN) is a two-component, fixed-bearing fourth generation total ankle arthroplasty (TAA) system that was introduced for clinical use in 2016. Few studies have investigated short-term outcomes of this new TAA system, and no outcomes have yet been reported by independent authors. The purpose of this study was to report non-inventor, non-industry funded survivorship, radiographic and clinical outcomes, and early complications following use of the new fourth generation TAA system at a minimum of 2 years. Methods: This is a single-center retrospective study of patients who underwent TAA by two surgeons with the Cadence between January 2017 and September 2018. There were 50 ankles in 50 patients, and 48 (96%; mean age of 66.1 years) patients were evaluated at a minimum 2-year follow-up. Two patients were lost due to death and refusal to participate in the study. Patients had an average follow-up of 33.6 (range, 24-50) months. Radiographic outcomes included preoperative and postoperative tibiotalar alignment (TTA) on anteroposterior radiographs of the ankle, sagittal tibial alignment (STA) on lateral radiographs of the ankle, and periprosthetic cyst formation (greater than 5mm in size) and cyst location. Data regarding reoperations and revisions were also collected. Patient-reported outcomes were assessed using Patient Reported Outcomes Measurement Information System (PROMIS). Subgroup analysis was performed to assess for associations between preoperative deformity, postoperative implant alignment, PROMIS scores, and periprosthetic cyst formation. Results: Survivorship of implant was 93.7%, with 3 revisions, 1 due to infection and 2 due to loosening of the implant (one tibial and one talar component). Three patients had reoperations (6.3%): 2 for irrigation and debridement for cellulitis, and 1 for gutter debridement due to medial gutter impingement. Preoperatively, 9 ankles had varus alignment (mean TTA 77.9 degrees), 20 had neutral alignment (mean TTA 90.2 degrees), and 13 had valgus alignment (mean TTA 102.9 degrees). Postoperatively, TTA and STA significantly improved, and all patients demonstrated neutral coronal alignment (TTA between 85 and 95 degrees). Fifteen patients (35.8%) developed periprosthetic cysts, all on the tibial side. PROMIS scores improved after surgery in all domains except Depression (Table 1). Patients with postoperative periprosthetic cysts had a smaller preoperative STA and a worse postoperative PROMIS Physical function and Pain interference domain than patients without periprosthetic cysts (p

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

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

Category: Ankle Arthritis; Ankle Introduction/Purpose: Total ankle replacements (TAR) have rapidly advanced in terms of volume, technique, design, and indications. However, they are still at risk for failure and need for revision, even early in the postoperative period. Although recently there has been extensive research on TAR, many studies are limited in their power and sample size to assess risk factors for failure/revision. Using a large multi-surgeon retrospective database, we sought to describe the incidence and etiology of mechanical failure across modern implants. We also aimed to identify risk factors for early mechanical failure. We hypothesized that greater body mass index (BMI) and ipsilateral hindfoot fusion would be predictors of mechanical failure, and that implants with greater extent of tibial fixation (stems and keels) would be protective against mechanical failure. Methods: This is a single-center retrospective review of TAR patients in a prospective database. Adults undergoing primary TAR using any implant (Cadence, Inbone, Infinity, Invision, Salto, STAR, Vantage, Zimmer) who were minimum 2 years post-surgery were included. Exclusion criteria included revision TAR or patients undergoing ankle fusion takedown and conversion to TAR. Five surgeons contributed patients. Demographics, etiology of arthritis, operative data, and postoperative complications, reoperations, and revisions were collected. Revisions and reoperations were classified by standard criteria. Cause of revision was recorded. There were 560 TARs eligible for 2-year follow-up (mean 3.9 +- 1.1 years postoperative), with mean follow-up of 2.2 +- 1.4 years (range 1-71 months). The cohort had mean age 63.8 +- 9.1 years, BMI 29.4 +- 5.2 kg/m2, and 57% were male. Kaplan- Meier survival plots were created. Risk factors for revision due to mechanical failure were analyzed using multivariable logistic regression with partial Wald chi square statistics. Results: Most implants were low-profile (n=444, 79.3%), with 28 implants having tibial keels (5%) and 88 with tibial/talar stems (15.7%). There were 25 (4.5%) revisions of tibial and/or talar components at mean 1.6 years after index surgery (Figure). Preoperative coronal deformity did not impact revision rates (p=0.433). Patients who underwent revision for mechanical failure had significantly higher rates of concomitant hindfoot fusion (20% vs. 8.4%, p=0.047) and greater BMI (31.4 kg/m2 vs. 29.3 kg/m2, p=0.04). In multivariable logistic regression, hindfoot fusion was just short of statistical significance (odds ratio [OR] 2.96, p=0.056), and BMI was not significant (OR 1.05, p=0.417). Stemmed or keeled implants did not significantly decrease revision rates compared to low-profile implants, although the revision rate of stemmed implants was substantially low (1/88, 1.1%). Conclusion: Among 560 modern TAR implants, short-term survivorship was 95% at 2-year follow-up, which is consistent with existing studies. Patients who underwent revision for early mechanical failure had significantly higher BMI and rates of hindfoot arthrodesis. However, these variables fell short of statistical significance in multivariable regression, suggesting that there are either additional factors contributing to revision, or a larger cohort is needed. In addition, these results are likely biased by surgeons' tendencies to use stemmed implants in patients with hindfoot fusions. Further research is warranted to determine if stemmed implants provide a protective effect in these high-risk patients.

Category: Ankle; Ankle Arthritis; Basic Sciences/Biologics Introduction/Purpose: Clinical and functional improvement after total ankle arthroplasty (TAA) in end-stage ankle arthritis has been well documented. However, despite the implantation of TAA devices designed to restore normal walking kinematics, patients with end-stage arthritis develop compensatory walking patterns which do not return to normal, postoperatively. This discrepancy between the normative and adaptive gait patterns could influence implant loading and intended function; however, the independent influence of implant constraints and adaptive gait on joint function is unknown. Therefore, this study aimed to isolate the individual and combined effects of TAA implantation and gait adaption from ankle arthritis on foot and ankle kinematics during simulated level walking. We hypothesized that foot and ankle kinematics would primarily be altered through adaptations in gait resulting from ankle arthritis. Methods: Twelve mid-tibia cadaveric specimens were utilized. A validated six-degree of freedom robotic gait simulator was used to simulate the stance phase [3]. The specimen was first placed on the simulator in the intact condition, simulated with both healthy and adaptive gait inputs collected from healthy and post-surgical TAA subjects (average follow-up: 46 months), respectively. The TAA (Salto Talaris; Integra LifeSciences) was then implanted, and adaptive and healthy gait trials were conducted in the implanted condition. Four conditions were collected on each specimen: intact with a healthy walking trajectory (intact- healthy), intact with an adaptive walking trajectory (intact-adaptive), implanted with TAA with a healthy walking trajectory (TAA- healthy), and implanted with TAA with an adaptive gait trajectory (TAA-adaptive). Ankle, subtalar, and talonavicular joint kinematics in each condition were compared to intact-healthy to isolate the effects of implantation and adaptive gait on kinematics. Bias-corrected 95% confidence intervals were calculated for the difference between conditions. Results: Significant differences were observed in the ankle, subtalar, and talonavicular joints across all comparisons. In the comparison between the intact-healthy and intact-adaptive conditions, to isolate the effect of adaptive gait (Figure 1A), ankle dorsiflexion and subtalar eversion increased late in stance, while talonavicular abduction increased in early and late stance. In the comparison between intact-healthy and TAA-healthy conditions, to isolate the effect of implant constraints (Figure 1B), ankle plantarflexion, subtalar eversion, and talonavicular abduction significantly increased in mid-stance after implantation. In the comparison between the intact healthy and the TAA-adaptive conditions, to evaluate the combined effect of adaptive gait and implantation (Figure 1C), ankle plantarflexion was increased during early stance and decreased in late stance, subtalar eversion increased during mid-to-late stance, and talonavicular abduction increased throughout most of the stance phase. Conclusion: The results from this study indicate that both gait adaption and implant constraint contributed to changes in ankle and adjacent joint kinematics. The two factors appear to influence different aspects of the stance phase, where gait adaption appeared to influence early, and late stance and implantation influenced kinematics in mid-stance. The synergistic influence of both factors seemed to exaggerate deviations away from normal kinematics in the subtalar and talonavicular joints while negating deviations from normal in the ankle joint. This suggests that ankle implants designed to restore normative walking patterns may not account for the loading environment seen in patients.

Category: Ankle Arthritis Introduction/Purpose: One of the proposed benefits of total ankle replacement, when compared to ankle fusion is the preservation of range of motion (ROM) of the ankle. Preservation of ankle motion may improve quality of life as evidenced by patient-reported outcome measures (PROMs). However, despite improving dorsiflexion intraoperatively during TAR, studies have not demonstrated large improvements in dorsiflexion (DF) at final followup after TAR. The objective of this study was to radiographically evaluate and quantify preoperative, intraoperative ankle dorsiflexion and plantarflexion (PF), compare it to post- operative ankle ROM, and determine the effect of Achilles lengthening (TAL) on preserving dorsiflexion motion that is gained during surgery. Methods: This prospective study compared 111 patients with an average age of 62.3 years who underwent primary total ankle replacement with one of four different implants between March and December 2019. A total of 71 patients (64%) had an associated TAL based on the surgeon's decision. Intraoperative fluoroscopy was utilized by the primary surgeon to document the maximal dorsiflexion and plantar flexion at the end of the case. This was completed after the TAL on a perfect lateral. Standardized weight bearing at maximum ROM positions lateral radiographs were obtained twelve months postoperatively. The change in range of motion was analyzed using a paired t-test with a significance level of 0.05. Results: The cohort's preoperative range was 22.0° (8.1°DF, 14°PF) and was increased to 38.5° intraoperatively (12.7°DF, 25.8°PF) as described in Table 1. Postoperative ROM is 24.9° (11.7°DF, 13.2°PF) which means that 65% of the intraoperative ROM is preserved. Preoperative and intraoperative range of motion was not different between the group that had a TAL compared to no TAL. At the year postoperatively, the dorsiflexion was similar between both groups. The group who did not have a TAL went from 12.8 intraoperatively to 12.2° postoperatively whereas the group who had a TAL went from 12.2° to 11.3° which was statistically equivalent. Conclusion: This study is the first to assess how much ankle range of motion is retained after TAR. Overall, we observed that 65% of dorsiflexion was retained after TAR. TAL as a concomitant procedure did not effect the proportion of dorsiflexion motion that was retained. Additional studies are needed to determine how to best optimize and increase ROM after TAR.

Category: Basic Sciences/Biologics; Hindfoot Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a 3-dimensional pathology associated with insufficiency of the posterior tibial tendon (PTT), ligamentous failure, joint malalignment, and aberrant plantar force distribution. Existing knowledge of PCFD consists of static measurements, which provide information about the structure of the foot but none about its function. Cadaveric gait models provide an opportunity to measure motion both at the joints primarily affected in PCFD and the adjacent joints that are at risk for progressive subluxation and arthritis. This study sought to develop a flatfoot model for a robotic gait simulator and quantify gait kinematics and plantar pressure between normal and flatfoot conditions, which we hypothesized would be altered after the creation of a flatfoot deformity model. Methods: Cadaveric specimens were loaded on a 6-degree of freedom robotic gait simulator and the extrinsic tendons were attached to linear motors. Ground reaction forces and muscle forces were optimized utilizing an established iterative process. An 8-camera motion capture system was utilized to calculate joint kinematics using reflective markers attached by k-wires into bone. A plantar pressure mat attached to the force platform was used to calculate the center of pressure excursion index (CPEI) for each condition. The flatfoot model was created via sectioning of the spring ligament and medial talonavicular joint capsule followed by cyclic axial compression until 5-15° of talonavicular abduction was achieved in a static, loaded pose. Testing of the flatfoot state was then performed with inactivation of the PTT. Bias-corrected bootstrapped 95% confidence intervals were constructed from the repeated measures difference between flatfoot and normal conditions. Paired t-tests were used to compare the CPEI between conditions. Results: Twelve mid-tibia cadaveric specimens (mean age 73 years, 8 female) with no prior foot/ankle surgery were used. There were significant differences in kinematics between normal and PCFD conditions at the ankle, subtalar, and talonavicular joints (Figure). There was significantly increased ankle plantar flexion in flatfoot in the first 80% of stance phase. There was significantly greater subtalar eversion in flatfoot compared to normal from 10-90% of stance phase. Talonavicular abduction and eversion were also significantly greater in flatfoot from 10-100% of stance. The CPEI was significantly decreased in the flatfoot condition (Figure), indicating a medialization in center of pressure (p

Category: Basic Sciences/Biologics; Hindfoot Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a complex 3-dimensional pathology with a wide variety of surgical treatments. Regardless of technique, operative management of PCFD aims to restore normal foot architecture with attention to avoid the consequences of under- or over-correction. However, current methods of evaluating PCFD correction rely on static measurements, which do not assess dynamic function of the foot. Recent advances in robotic technology allow for the dynamic assessment of surgical correction of PCFD. This study sought to assess the effects of 2 osteotomies for PCFD, the medializing calcaneal osteotomy (MCO) and lateral column lengthening (LCL), on kinematics and plantar pressure during simulated gait. We hypothesized that the combination of LCL and MCO would restore joint kinematics and plantar pressure values to normal levels. Methods: Twelve cadaveric mid-tibia specimens (mean age 73 years, 8 female) were loaded on a 6-degree of freedom robotic gait simulator. Ground reaction forces and muscle forces were optimized utilizing an established iterative process. An 8-camera motion capture system was utilized to calculate joint kinematics using reflective markers attached by k-wires into bone. Plantar pressures were recorded using a pedography mat attached to the force platform. Testing was performed first in the native intact state, and again after creation of the flatfoot model. After flatfoot testing, surgical reconstruction and testing were performed in stages with MCO, and LCL with sequential 6mm and 8mm grafts. Bias-corrected bootstrapped 95% confidence intervals were calculated from the repeated measures difference between normal, flatfoot, post-MCO, post-MCO and post-reconstructive conditions. Center of plantar pressure excursion index (CPEI) was calculated and compared between conditions using a repeated measures ANOVA with Tukey post hoc analysis. Results: Overall, surgical correction restored kinematics to normal levels (Figure). MCO alone resulted in statistically significant improvement in subtalar eversion in the first 20% of stance, and post-MCO subtalar kinematics were statistically similar to normal. LCL (either 6mm and 8mm) alone did not significantly correct talonavicular abduction after PCFD. However, in conjunction with MCO, LCL was able to significantly correct talonavicular kinematics throughout the majority of stance phase, with kinematics statistically similar to normal levels. Each surgical step (LCL 6mm, LCL 8mm, MCO) resulted in sequential lateralization of the center of plantar pressure. At the culmination of surgical reconstruction (MCO + LCL), plantar pressure was significantly corrected compared to PCFD (P

Category: Ankle; Ankle Arthritis Introduction/Purpose: The treatment of ankle arthritis has changed significantly with the recent advances in total ankle arthroplasty (TAR). Many different designs of TAR have been used around the world as the biomechanical technology advances and our understanding increases. Most implant system are anterior-based and have a flat cut on the tibial prosthesis. Only one implant, the Trabecular Metal (Zimmer-Biomet, Warsaw, IN), utilizes a lateral approach with a fibular osteotomy to gain access to the tibiotalar joint and a sagittally curved tibial component. Recent publications have described a higher reoperation rate with this implant system. This study aimed to report the 5-year clinical and radiographic outcome as well as the survivorship of the implant. Methods: Over a three-year period, two fellowship-trained foot and ankle surgeons used this implant system for patients indicated for TAR. A total of 38 patients were reviewed with an average age of 63.4+-8.6 years-old, BMI of 28.9+-4.6 and the majority (78%) had post-traumatic arthritis. Reoperations and revisions were collected prospectively as part of the local database. Patients participated in surveys preoperatively and at every annual follow-up which included the Foot and Ankle Outcome Score (FAOS). Patients were also evaluated with weightbearing radiographs preoperatively, at the 3 months postoperative and at the 5 year-mark. Those were analyzed by looking at the implant position with validated angles and comparing those over time. Further statistical analysis used paired t-test and Mann-Whitney U test. Results: The survivorship for our cohort was 92% at the 5-year mark. Three patients had the implant extracted at 12 and 15 months postoperative. Two of those patients had revisions to stemmed TARs and one had a below-knee amputation. Reoperations otherwise included 4 fibular hardware removal and 5 medial gutter debridement. As seen in Table 1, the FAOS improved significantly for all domains at 5-year compared to preoperative status. The Pain and Symptoms domains improved above than the MCID. The implant positioning both tibial coronal and sagittal as well as talar sagittal did not significantly change between 3 months and 5 years postoperative. Conclusion: This study describes the use of a laterally based Trabecular Metal TAR with great survivorship (92%) and clinically significant improvement in patient-reported outcomes. The rate of reoperation is higher due to prominent lateral hardware or poorly visualized medial gutters and revisions had to be performed through an anterior approach. Few other studies report 5-year outcomes from this prosthesis. There is a growing need to present more data from different centers to guide its ongoing clinical use.

Background: There is no current consensus on whether to use an open or minimally invasive (MIS) approach for Achilles tendon repair after acute rupture. We hypothesized that patients in both open and MIS groups would have improved patient-reported outcome scores using the PROMIS system postoperatively, but that there would be minimal differences in these scores and complication rates between operative techniques. Methods: A total of 185 patients who underwent surgery for an acute, unilateral Achilles tendon rupture between January 2016 and June 2019, with minimum 1-year follow-up were included in the cohort studied. The minimally invasive group was defined by use of a commercially available minimally invasive device through a smaller surgical incision (n=118). The open repair group did not use the device, and suture repair was performed through larger surgical incisions (n=67). Postoperative protocols were similar between groups. Preoperative and postoperative PROMIS scores were collected prospectively through our institution’s registry. Demographics and complications were recorded. Results: PROMIS scores overall improved in both study groups after operative repair. No significant differences in postoperative PROMIS scores were observed between the open and MIS repair groups. There were also no significant differences in complication rates between groups. Overall, 19.5% of patients in the MIS group had at least 1 postoperative complication (8.5% deep vein thrombosis [DVT], 3.3% rerupture, 1.7% sural nerve injury, 2.5% infection), compared to 16.4% in the open group (9.0% DVT, 1.5% rerupture, 1.5% sural nerve injury, 0% infection). Conclusion: Patients undergoing either minimally invasive or open Achilles tendon repair after acute rupture have similar PROMIS outcomes and complication types and incidences. Level of Evidence: Level III, retrospective cohort study.

Background: Despite good evidence that supports significant improvements in pain and physical function following a total ankle replacement (TAR) for end-stage ankle arthritis, there is a subset of patients who do not significantly benefit from surgery. The purpose of this study was to perform a preliminary analysis to determine if preoperative Patient-Reported Outcome Measurement Information System (PROMIS) scores could be used to predict which patients were at risk of not meaningfully improving following a TAR. Methods: Prospectively collected preoperative and ≥2-year postoperative PROMIS physical function, pain interference, pain intensity, and depression scores for 111 feet in 105 patients were included in the study. Significant postoperative improvement was defined using minimal clinically important differences (MCIDs). Logistic regression models and area under the curve (AUC) analyses were used to determine whether preoperative PROMIS scores were predictive of postoperative outcomes. Results: Receiver operating characteristic curves found statistically significant AUCs for the PROMIS physical function (AUC = 0.728, P = .004), pain intensity (AUC = 0.720, P = .018), and depression (AUC = 0.761, P < .001) domains. The preoperative PROMIS pain interference domain did not achieve a statistically significant AUC. Conclusion: Preoperative PROMIS physical function and pain intensity t scores may be used to predict postoperative improvement in patients following a fixed-bearing TAR; however, preoperative PROMIS pain interference scores were not good predictors. The results of this study may be used to guide research regarding patient-reported outcomes following TAR. Level of Evidence: Level III, retrospective comparative series.

Category: Ankle Arthritis; Ankle Introduction/Purpose: The use of total ankle arthroplasty (TAA) in the treatment of ankle arthritis has grown substantially as advancements are made in design and surgical technique. Among the criteria guiding the choice between arthroplasty versus arthrodesis, the long-term survival and postoperative outcomes are of crucial importance. First FDA approved in 2005, the INBONE I prosthesis was subsequently replaced by the INBONE II in 2010. While outcomes of the INBONE I have been published, there is limited long-term survivorship data for the INBONE II. The purpose of this study is to determine the minimum 5-year survivorship of the INBONE II prosthesis and causes of failure. In addition, we evaluate long-term radiographic and patient- reported outcomes. Methods: We retrospectively identified 46 prospectively followed patients from 2010 to 2015 who underwent TAA with the INBONE II prosthesis at our institution. Of these, 44 cases (41 patients) had minimum follow-up of 5 years (mean, 6; range, 5 to 9). Mean age was 65.6 years (range, 42 to 81) and mean BMI was 27.6 (range 20.1 to 33). Survivorship was determined by incidence of revision, defined as removal/exchange of a metal component. Chart review was performed to record incidences of revision and reoperation. Preoperative, immediate and minimum 5-year x-rays were reviewed; coronal tibiotalar alignment (TTA) was measured on standing AP radiographs to assess alignment of the prosthesis. A TTA of +-5° from 90° indicated neutral alignment, while 95° was considered varus and valgus alignment, respectively. Radiographic subsidence as well as presence and location of periprosthetic cysts were documented. Pre- and minimum 5-year FAOS domains were compared. Results: Survivorship was 97.7% with one revision of the talar component due to aseptic loosening and subsidence. The rate of other reoperations was 4.5% (2); one patient underwent medializing calcaneal osteotomy for valgus heel alignment, another patient underwent ostectomy and debridement for ankle impingement. Average preoperative TTA was 88.5 degrees with 15 neutral (average TTA of 89.7°), 14 varus (74°) and 12 valgus (104°) ankles. Average postoperative TTA was 88.6° with 35 neutral (89.3°), 6 varus (84.7°), and no valgus ankles. Radiographic subsidence was observed in one patient who underwent revision, and periprosthetic cysts were observed in 7 patients. There was significant improvement in all FAOS domains at final follow-up. Conclusion: This is the largest study to date dedicated to evaluating survivorship of the INBONE II prosthesis. Our data suggests a high survival rate and low reoperation rate with long-term follow-up of the INBONE II implant. We observed significant improvement in radiographic alignment as well as patient-reported clinical outcomes at minimum 5-year follow-up.

Category: Ankle; Ankle Arthritis; Trauma Introduction/Purpose: Although total ankle replacement (TAR) for the treatment of end-stage ankle arthritis has been shown to have excellent radiographic and clinical outcomes, there is a risk for complications such as periprosthetic fractures. While periprosthetic fractures of the tibia are well described in the literature, little is known about such fractures involving the talus. The purpose of this case series is to describe the radiographic findings and surgical management of talar fractures sustained after placement of total ankle prostheses. Methods: We retrospectively reviewed 489 patients who underwent total ankle replacement from June 2015 to March 2019, and identified five cases (2 males, 3 females, average age 45.7 years) in which patients sustained a periprosthetic fracture of the talus. All patients presented symptomatically with ankle pain during postoperative follow-up, and fractures of the talus were confirmed on computed tomography (CT) imaging. One patient had psoriatic arthritis and four patients had primary osteoarthritis of the ankle. CTs were reviewed to confirm location and pattern of the fracture, as well as related pathology such as osteolysis and subsidence. Hospital charts and operative reports were reviewed to record patient demographics and postoperative management including reoperations. Results: Overall the incidence of talar fractures was 1% (5/489) and all occurred in implants with a talar stem (4 INBONE II, 1 Salto Talaris). All fractures extended from the stem of the talar component into the subtalar joint, with one case of a non- displaced fracture. Osteolysis surrounding the talar stem was observed in all cases, with subsidence of the talar component observed in four out of five patients on CT. All five patients presented symptomatically and underwent reoperation (1 revision of talar component with ORIF, 3 subtalar fusions, 1 tibiotalar fusion). Conclusion: The findings in this case series suggest that periprosthetic fractures of the talus following total ankle replacement is a possible complication of stemmed implants and is associated with poor clinical outcomes requiring reoperation. Therefore, a periprosthetic fracture of the talus should be considered in a patient with unexplained pain and evidence of radiographic osteolysis around the stemmed component.

Category: Ankle Arthritis; Ankle Introduction/Purpose: Total ankle arthroplasty (TAA) has garnered significant interest and increased use over the past decade, with advancements made in both design and surgical technique. The main advantage of TAA for the surgical treatment of ankle arthritis is to preserve range of motion compared to ankle arthrodesis. Among the criteria guiding the choice between arthroplasty and arthrodesis, the long-term survival and postoperative outcomes are of crucial importance. The Salto Talaris is a fixed-bearing implant first approved in the US in 2006, and long-term survivorship data is limited. The purpose of this study is to determine minimum 5-year survivorship of the Salto Talaris prosthesis and causes of failure. In addition, we evaluate long-term radiographic and patient-reported outcomes. Methods: We retrospectively identified 86 prospectively followed patients from 2007 to 2014 who underwent TAA with the Salto Talaris prosthesis at our institution. Of these, 81 patients (84 feet) had a minimum follow-up of 5 years (mean, 7.1; range, 5 to 12). Mean age was 63.5 years (range, 42 to 82) and mean BMI was 28.1 (range, 17.9 to 41.2). Survivorship was determined by incidence of revision, defined as removal/exchange of a metal component. Chart review was performed to record incidences of revision and reoperation. Preoperative, immediate and minimum 5-year postoperative x-rays were reviewed; coronal tibiotalar alignment (TTA) was measured on standing AP radiographs to assess alignment of the prosthesis. A TTA of +-5° from 90° indicated neutral alignment, while 95° was considered varus and valgus alignment, respectively. Radiographic subsidence as well as presence and location of periprosthetic cysts were documented. Pre- and minimum 5-year FAOS domains were compared. Results: Survivorship was 97.6% with two revisions. One patient underwent tibial and talar component revision for varus malalignment of the ankle, another underwent talar component revision for aseptic loosening and subsidence. The rate of other reoperations was 19.5% (18) with the main reoperation being exostectomy with debridement for ankle impingement (12). Average preoperative TTA was 88.8° with 48 neutral (average TTA of 90.1°), 18 varus (82.3°) and 8 valgus (99.6°) ankles. Average postoperative TTA was 89.0° with 69 neutral (89.7°), 6 varus (83°), and 1 valgus ankle (99.3°). Radiographic subsidence was observed in one patient who underwent revision, and periprosthetic cysts were observed in 18 patients. There was significant improvement in all FAOS domains at final follow-up. Conclusion: This is the largest study to date dedicated to evaluating survivorship of the Salto Talaris prosthesis. Our data reflects a high survival rate and moderate reoperation rate with long-term follow-up of the Salto Talaris implant. We observed significant improvement in radiographic alignment as well as patient-reported clinical outcomes at minimum 5-year follow-up.

Category: Ankle Introduction/Purpose: Biologic fixation of total joint replacements by bone ingrowth requires minimal bone-implant micromotion [1]. Computational finite element (FE) models used to evaluate the interaction between implant and bone typically only consider simplified loading conditions based on the peak compressive force which occurs near toe-off [2,3]. However, a previous study focused on cementless knee replacements demonstrated that peak micromotion during activity cycles occurred with sub-maximal forces and moments [4]. Our objective was to calculate multi-axial loading at the ankle joint throughout level walking and evaluate tibial fixation of ankle replacements under these loading conditions. We hypothesized that peak micromotion would occur with sub-maximal loads and moments instead of at the instant of peak compressive load. Methods: Our validated six-degree-of-freedom robotic simulator utilizes in vivo data from human subjects to replicate the individual bone kinematics in cadaveric specimen throughout activity [5]. We rigidly fixed retro-reflective markers using bone pins to the tibia, talus, and calcaneus bones of three cadaveric specimens to record individual bone kinematics using motion capture cameras. We recorded the ground reaction and muscle-tendon forces during the simulated stance phase of level walking. Musculoskeletal models were then developed in OpenSim using the specimen-specific morphology and implant position from CT- scans and from the simulator outputs to determine the loading profile at the ankle joint during stance. The calculated loads were then applied to specimen-specific finite element models to evaluate the bone-implant interaction. Peak micromotion at each time point of loading was measured and compared to the loading profile to determine if it corresponded with the peak compressive load. Results: For all specimens, the peak compressive load at the ankle joint was accompanied by multi-axial moments and relatively small shear forces (Figure 1). The peak compressive load for each specimens was between 750 N and 850 N and occurred during 75-80% of gait. The largest moment experienced by all specimens was an internal moment late in stance. The peak micromotion for each specimen did not correspond to the instance of peak compressive load, as indicated in Figure 1. Instead, peak micromotion occurred at 54%, 88%, and 96% of gait. For each specimen, these instances corresponded to the combination of a sub-maximal compressive load with high eversion and internal moments. Conclusion: We have developed a workflow to calculate ankle joint loads corresponding to cadaveric simulations that reproduce a daily activity based on in vivo data. The specimen-specific, multi-axial loading profile at the ankle for our initial results suggests that peak micromotion at the bone-implant interface of the tibial implant does not coincide with the peak compressive force. The instant of peak compressive load may not capture the worst-case scenario for the interaction between the implant and the bone. Instead, the multi-axial forces and moments at the ankle joint throughout activity should be considered when evaluating implant fixation.

Category: Ankle Arthritis Introduction/Purpose: One of the proposed benefits of total ankle replacement (TAR), when compared to ankle fusion is the restoration of the functional range of motion (ROM) of the ankle. Preservation of ankle motion may improve quality of life as evidenced by patient-reported outcome measures (PROMs). However, some studies have shown a lack of improvement of ankle range of motion after the postoperative recovery period, despite satisfactory motion being observed intra-operatively. The objective of this study was to radiographically compare intraoperative and pre-operative ankle range of motion. Methods: This single-center retrospective study compared 56 patients with an average age of 62.27 years who underwent primary TAR with one of four different implants between March and December 2019. 48% of patients had post-traumatic arthritis secondary to an ankle fracture, 50% had post-traumatic arthritis secondary to instability. Seventy-two percent of patients had an associated Achilles lengthening, 16% had an associated lateral ligament reconstruction procedure. Standardized weight-bearing maximum dorsiflexion and plantarflexion sagittal radiographs were obtained pre-operatively. In order to record intraoperative fluoroscopic imaging, the primary surgeon passively placed the ankle into maximum dorsiflexion and plantarflexion. Intraoperatively, the neutral lateral position of the ankle was determined after the replacement when the talus was in perfect lateral view. All angular measurements were made using the PACS system (Picture Archiving and Communication System). The change in range of motion was analyzed using a paired t-test with a significance level of 0.05. Results: The intraoperative range of motion increased significantly for all measures when compared to the pre-operative range of motion. The average pre-operative global arc of motion significantly increased from 20.21 degrees to 38.49 degrees intra- operatively (p=2.45x10-18, t(55)=2.00). The average pre-operative plantar flexion significantly increased from 12.80 degrees to 25.50 degrees intra-operatively (p=2.56x10-15, t(55)=2.00). The average pre-operative dorsiflexion significantly increased from 7.28 degrees to 13.35 degrees intra-operatively (p=4.68x10-6 t(55)=2.00). Patients who had an Achilles lengthening had an average increase in the global arc of motion of 18.78 degrees; patients who did not have an Achilles lengthening had an average increase of 17.02 degrees (p=0.562, t(31)=2.04). Overall, 93% of patients increased their range of motion after their total ankle replacement. Conclusion: This study demonstrates notable improvement in ankle range of motion intraoperatively following total ankle replacement, especially in plantarflexion. Total Ankle Replacement provides an improvement in the functional range of motion of the ankle intraoperatively, suggesting that the loss of motion observed in previous studies may occur during the postoperative period. The present study may help inform and adjust the postoperative rehabilitation protocol after total ankle replacement in order to avoid losing the amplitude of motion gained during the operation.

Category: Ankle; Ankle Arthritis Introduction/Purpose: Surgeons who perform a higher volume of total ankle arthroplasty (TAA) are known to have decreased complication rates; evidence shows that low volume centers performing TAA have decreased survivorship when compared with high volume centers. Understanding differences in outcomes for patients traveling different distances for their TAA is important for future patients deciding where to travel for their surgery. No study has previously examined differences in outcomes of patients traveling different distances to a high volume center for their TAA. This study compares preoperative and postoperative PROMIS scores for patients undergoing total ankle arthroplasty who traveled less than and more than 50 miles for their TAA. We hypothesized that there would be no difference in outcome scores based on distance traveled or estimated drive time. Methods: This study is a single center retrospective review of 162 patients undergoing primary total ankle arthroplasty between January 2016 and December 2018. We collected the primary address as listed in the patient’s medical record and used the directions feature on Google Maps to estimate driving mileage and estimated driving time from the patient’s address to the hospital. To analyze the distance patients traveled, patients were divided into two groups: 50 miles traveled (n=71). To analyze the estimated drive time, patients were divided into two groups: 90 minutes (n=85). We collected preoperative and most recent postoperative PROMIS scores for all patients. Differences in most recent post-operative PROMIS scores between distance groups and travel time groups were assessed using multivariable linear regression models, adjusting for the pre-operative score and follow-up time. Results: We found no significant difference in post-operative PROMIS scores between the two groups when analyzed for distance traveled or for estimated travel time after adjustment for pre-operative PROMIS score and follow-up time (Table 1). The average follow-up for all 162 patients was 1.49 years. Power analysis showed that with a sample size of 110 (55 in each group), we had 81% power to detect an effect size of 4. Patients saw an increase in their Physical Function scores and a decrease in their Pain Interference and Pain Intensity scores with postoperative scores better than population means (Table 1). Overall complication rate for the 50 miles group had an overall complication rate of 24.0%, 9.9% required surgery. Conclusion: Patients traveling further distances to a high volume orthopedic specialty hospital for their total ankle arthroplasty do not have different clinical outcomes than patients traveling shorter distances. This is particularly important for patients deciding where to have their total ankle arthroplasty surgery. Patients who travel further have the opportunity to be treated at a local academic center; however our results show that outcomes do not change when traveling further for total ankle arthroplasty.

Category: Other Introduction/Purpose: Cases of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus (COVID-19) first emerged in Wuhan, China, in December 2019. Since then, the virus has spread globally at a rapid pace. The first case in New York City was reported on March 1, 2020, and the World Health Organization (WHO) declared a pandemic on March 11, 2020. New York City rapidly became the epicenter of the pandemic, with hospitals across the city making a number of changes to accommodate the influx of COVID-19 patients. Here, we describe our experience in adapting to the COVID-19 pandemic as a department consisting of 10 foot and ankle fellowship-trained surgeons with up to 28 years of individual experience in an academic orthopedic hospital. Methods: Information was obtained from direct interviews with surgeons in the Foot and Ankle Service and from our institution’s intranet. Additional information was obtained by viewing twice-weekly livestreams from March 27th, 2020 to May 1st, 2020 held by the Surgeon-In-Chief, which detailed hospital-wide policies and initiatives being implemented in the wake of the COVID-19 pandemic. Results: On March 17, 2020, all elective surgeries were suspended at our institution, and a list of essential procedures was established. In-person clinical visits were limited to new patients being evaluated for essential procedures and first postoperative visits for returning patients, with all patients receiving pre-visit and on-site screening for COVID-19. All other new patient and follow-up appointments were conducted via telehealth visits. Much of our main hospital was repurposed to accept transfers of both COVID-negative and COVID-positive patients. A postanesthesia care unit and a floor of 9 operating rooms were repurposed as negative-pressure rooms for the care of critical COVID-positive patients on ventilators. An Orthopedic Triage Center (OTC) was established to relieve the patient load in the emergency departments of other hospitals in the city. Conclusion: By changing the way we delivered foot and ankle care and repurposing the roles of our employees and our institution, we have adapted strategies to continue delivering care to our patients. As we transition toward a ‘new normal,’ our goals are to gradually progress toward normal operations while keeping our patients and employees safe. With these gradual steps, we hope to emerge from this pandemic stronger and ready to adapt to the ever-changing needs of our community.

Category: Sports Introduction/Purpose: While there is no current consensus on whether to use an open or minimally invasive (MIS) approach for Achilles tendon repair after acute rupture, there is a recent trend towards decreasing complication rates for both procedures as well as favorable clinical outcomes. While many studies have compared complication rates between these procedures, no study has examined differences in clinical outcomes using PROMIS scores with a large cohort of patients. PROMIS has been validated for use in assessing outcomes following Achilles repair and allows for evaluation of surgical outcomes compared to population means. We hypothesized that patients in both open and MIS groups would have improved PROMIS scores postoperatively, but that there would be minimal differences in PROMIS scores and complication rates between surgical techniques. Methods: 228 patients were identified who underwent surgery for acute unilateral Achilles tendon repair between January 2016 and December 2018. Nine surgeons were represented. The open repair group was defined by a larger incision (>4 cm) and no use of a commercially available minimally invasive device. The minimally invasive group was defined by a smaller incision (

Category: Other Introduction/Purpose: Aligning patient and surgeon expectations is important, as it allows for informed and shared decision- making and may improve postoperative satisfaction. Patient-provider communication factors have been found to affect differences between patient and surgeon expectations of total knee arthroplasty. Patients with limited health literacy have been found to ask fewer questions and spend less time with their surgeons, and to perceive themselves to have a more passive decision-making role in hand surgery clinic visits. Understanding how these factors affect differences in expectations of foot and ankle surgery is important in order to increase patient-surgeon agreement. This study aimed to assess associations between patient-reported physical and mental status, patient-surgeon communication factors, and musculoskeletal health literacy with differences between patient and surgeon expectations of foot and ankle surgery. Methods: Two hundred two patients scheduled to undergo foot or ankle surgery by one of seven fellowship-trained foot and ankle surgeons at an academic hospital were enrolled. Preoperatively, patients and surgeons completed the Hospital for Special Surgery Foot & Ankle Surgery Expectations Survey independently. Patients also completed Patient-Reported Outcomes Measurement Information System (PROMIS) scores in Physical Function, Pain Interference, Pain Intensity, Depression, and Global Health. Patient involvement in care, provider partnership building, and provider information giving were assessed with the modified Patients’ Perceived Involvement in Care Scale (PICS). Musculoskeletal health literacy was assessed with the Literacy in Musculoskeletal Problems (LiMP) questionnaire. A score >= 6 reflects adequate musculoskeletal literacy and a score < 6 reflects limited musculoskeletal literacy. Associations between scores and differences between patient and surgeon expectations were assessed with Pearson Correlation coefficients. Associations between musculoskeletal health literacy and differences were assessed with Student’s t-tests and Mann Whitney U tests. Results: Greater differences in patient and surgeon overall expectations scores were associated with worse PROMIS scores in Physical Function (p = 0.003), Pain Interference (p = 0.001), Pain Intensity (p = 0.009), Global Physical Health (p < 0.001), and Depression (p = 0.009). A greater difference in the number of expectations between patients and surgeons was associated with all of the above (p = 0.155). Conclusion: Worse baseline patient physical and mental status and higher patient perceptions of provider partnership building were associated with greater patient to surgeon differences in expectations of foot and ankle surgery. It may be beneficial for surgeons to set more realistic expectations with patients who have greater disability and in those whom they have stronger partnerships with in order to increase agreement in expectations. Further studies are warranted to understand how modifications in patient and surgeon interactions affect agreement in their expectations of foot and ankle surgery, and whether musculoskeletal literacy affects these interactions.

Category: Midfoot/Forefoot; Sports Introduction/Purpose: Fractures of the fifth metatarsal occur in young, athletic populations and often result in sub-optimal clinical outcomes, even after surgical fixation. With such a high demand for decreased return to play in athletic populations, the development of intervention strategies which mitigate intrinsic and extrinsic risk factors of initial injury is important. Foot orthotics have been shown to decrease strain in the 2nd metatarsal. However, limited research has investigated the influence of intrinsic risk factors and the use of foot orthotics on fifth metatarsal strain. Therefore, the purpose of our study was to investigate the effect of foot orthotics and intrinsic risk factors on fifth metatarsal strain during cadaveric simulation. Methods: Ten specimens were loaded to simulate the stance phase of normal gait using a validated 6-degree of freedom robot with tendon actuators. Strain gauges were placed at the metaphyseal - diaphyseal junction (Zone II), and the proximal diaphysis (Zone III) to measure principal strain. Specimens were tested in a sneaker-only control condition and ten orthotic conditions, which include combinations of a commercial orthotic insole, three plates, and two foam wedges (Figure 1A). The average peak strain from three simulations were recorded for each orthotic condition. Relevant intrinsic factors were recorded from reconstructions of axially loaded computed tomography scans. A two-way repeated measures ANOVA was conducted to determine the effect of orthotic conditions on fifth metatarsal strains, with significantly correlated intrinsic factors included as covariates. Tukey-Kramer post-hoc analysis with a Bonferroni correction was used to analyze differences between individual orthotic conditions and main effects of components. Results: Metatarsus adductus angle, 4-5 intermetatarsal angle, and Meary’s angle (R2= 0.944; p

Background: The posteromedial ankle structures are at risk during total ankle replacement (TAR). The purpose of our study was to investigate the distance of these structures from the posterior cortex of the tibia and talus in order to determine their anatomy at different levels of bone resection during a TAR and whether plantarflexion of the ankle reliably moved these structures posteriorly. Methods: Ten feet in 10 patients with end-stage tibiotalar arthritis indicated for a TAR were included. Preoperative magnetic resonance images were obtained with the foot in a neutral position as well as in maximum plantarflexion to measure the distance of posteromedial ankle structures to the closest part of the posterior cortex of the tibia or talus. Wilcoxon signed-rank rests were used to investigate differences in these distances. Results: The mean distance from the posterior tibial cortex to the tibial nerve at 14 and 7 mm above the tibial plafond was 8.7 mm (range 5.0-11.8 mm) and 6.7 mm (range 2.7-10.6 mm), respectively, which represented a statistically significant movement anteriorly ( P = .021). The posterior tibial artery was, on average, 8.0 mm (range 3.6-13.9 mm) and 7.2 mm (range 3.1-9.4 mm) from the posterior tibial cortex at 14 and 7 mm above the tibial plafond, respectively. Distal to the tibial plafond, the posterior tibial artery and flexor digitorum longus tendons moved posteriorly by less than 1 mm in plantarflexion (all P < .05); otherwise, plantarflexion of the ankle did not affect the position of the tibial nerve, posterior tibial tendon, or flexor hallucis longus. Conclusion: In patients with end-stage ankle arthritis, the tibial nerve and posterior tibial artery lie, on average, between 6.5 and 10 mm from the posterior tibial and talar cortices. Plantarflexion of the ankle did not reliably move the posteromedial ankle structures posteriorly. Level of Evidence: Level IV, case series, therapeutic

Background: Restoring the joint line is an important principle in total knee arthroplasty. However, the effect of joint line level on patient outcomes after total ankle arthroplasty (TAA) remains unclear, as there is no established method for measuring ankle joint level in TAA. The objective of this study was to develop a reliable radiographic ankle joint line measurement method and to compare ankle joint line level measured pre-TAA, post-TAA, and in nonarthritic ankles. Methods: A total of 112 radiographic sets were analyzed. Each set included weightbearing anteroposterior radiographs of the operative ankle taken preoperatively, 1-year postoperatively, and of the contralateral ankle. Measurements of vertical intermalleolar distance (VIMD) and vertical joint line distance (VJLD) at pre-TAA, post-TAA, and of the contralateral ankle were recorded by 2 authors on 2 separate occasions. The ratio of VJLD to VIMD was defined as the joint line height ratio (JLHR). Reliability of measurements and correlation between VIMD and VJLD were assessed. Pre-TAA, nonarthritic contralateral ankle, and post-TAA JLHR were compared and considered significantly different if P 0.9). There were strong positive correlations of VIMD and VJLD, r = 0.809 (pre-TAA)/0.756 (post-TAA), P < .001. Mean (SD) pre-TAA, nonarthritic contralateral ankle, and post-TAA JLHRs were 1.54 (0.31), 1.39 (0.26), and 1.62 (0.49), respectively. Pre- and post-TAA JLHRs were significantly higher compared to the nonarthritic contralateral ankle ( P < .05). JHLR was not significantly different between pre- and post-TAA ( P = .15). Conclusion: The JLHR was reliable and could be a clinically applicable method for assessing ankle joint line level in patients undergoing TAA. End-stage ankle arthritis demonstrated elevated joint line level compared with nonarthritic ankles, and the joint line level post-TAA remained elevated compared with nonarthritic ankles. Further studies are needed to understand the effect of joint line elevation on clinical outcomes after TAA. Level of Evidence: Level III, retrospective comparative study.

Category: Ankle Arthritis Introduction/Purpose: Total ankle replacement (TAR) continues to exhibit a relatively high incidence of complications and need for revision surgery, particularly when compared to knee and hip arthroplasty. One common mode of failure in TAR is talar component subsidence. This may be caused by disruption in the talar blood supply related to the surgical technique. Positron emission tomography (PET) imaging with [18F]-Fluoride has demonstrated utility in evaluating bone perfusion, and PET-CT in particular is useful in the setting of total joint replacement. In this study we aim to quantify changes in talar perfusion before and after TAR with the INBONE II system (Wright Medical Technology, Inc., Memphis, TN) using [18F]-Fluoride PET-CT. It is our hypothesis that perfusion to the talus would decrease after TAR. Methods: Eight subjects (5M/3F) aged 70.4 ± 7.5 years [Range 61-83] were enrolled for 18F-PET/CT imaging prior to and 3 months following TAR. 5–10 mCi of 18F-Fluoride was administered and dynamic acquisition in list mode for 45 minutes was performed on the operative and non-operative ankles simultaneously on a Siemens mCT Biograph scanner. Static acquisition of the whole body was also performed one hour after injection. Regions of interest (ROI’s) were placed on the postoperative CT images in the body of the talus beneath the INBONE II talar component. These regions were manually delineated on the preoperative CT scans, and were drawn to replicate the ROIs placed on the postoperative studies. ROI’s were overlaid on the fused static 18F-PET images and standard uptake values (SUVs) calculated for these regions as well as the whole foot. Changes in SUVs were analyzed using a paired t-tests with a significance level of 0.05. Results: We found no significant difference in bone perfusion in the talus after TAR in our cohort of patients. 18F uptake in the ROI underneath the talar component compared to that measured at baseline prior to surgery was 3.36 +/- 1.44 SUV postoperatively vs. 2.65 ± 1.24 SUV preoperatively, (p=0.33). Similar results were seen in the whole foot: 2.99 +/- 1.22 SUV postoperatively vs. 2.47 ± 0.75 SUV preoperatively (p=0.16). Figure 1 displays preoperative and postoperative uptake in the bone in the area corresponding to the base of the talar component. Although we did not find a significant difference in our initial study, the observed increase in perfusion to the talus after TAR may reach significance with a larger cohort of patients. Conclusion: 18F-PET demonstrates the ability to quantify changes in bone perfusion and metabolism following TAR. Our results suggest that the vascular blood supply to the talus is not disrupted after TAR. Additional pharmacokinetic analysis of the dynamic activity curves will also allow for estimates of bone blood flow and osteoblastic turnover via compartmental modeling. These results may be used to confirm the presence of adequate bone blood flow and vascularity in the body of the talus following total ankle replacement.

Background: Ankle fracture surgeries are generally safe and effective procedures; however, as quality-based reimbursement models are increasingly affected by postoperative readmission, we aimed to determine the causes and risk factors for readmission following ankle fracture surgery. Methods: Ankle fracture cases were identified from the prospectively collected American College of Surgeons National Surgical Quality Improvement Program from 2013 to 2014. Demographics, comorbidities, and fracture characteristics were collected. Rates of 30-day adverse events and readmissions were determined as well as the causes for readmission. Multivariable logistic regression analyses were performed to identify risk factors associated with having any adverse events and being readmitted within 30 days of surgery. Results: There were 5056 patients included; 167 (3.3%) were open fractures. The rate of any postoperative adverse event was 5.2%. There were 116 unplanned readmissions, with a readmission rate of 2.3%. Of the 116 unplanned readmissions, 49 (42.2%) were for reasons related to the surgery or surgical site, with the most common causes being deep surgical site/hardware infections (12.9%), superficial site infections (11.2%), and wound disruption (6.9%). Most readmissions were for reasons unrelated to the surgical site (51.7%), including cardiac disorders (8.6%), pulmonary disorders (7.8%), and neurological/psychiatric disorders (6.9%). The cause of readmission was unknown for 6% of readmissions. With multivariable logistic regression, the strongest risk factors for readmission were a history of pulmonary disease (odds ratio [OR], 2.29), American Society of Anesthesiologists (ASA) class ≥3 (OR, 2.28), and open fractures (OR, 2.04) (all P < .05). Conclusion: In this cohort of 5056 ankle fracture cases, 2.3% of patients were readmitted within 30 days, with at least 51.7% of all unplanned readmissions due to causes unrelated to the surgery or surgical site. Predictors of readmission included a history of pulmonary disease, higher ASA class, and open fractures. Based on these findings, we advocate close medical follow-up with nonorthopaedic providers after discharge for high-risk patients. Level of Evidence: Level III.

Category: Ankle Arthritis Introduction/Purpose: Patients undergoing total ankle arthroplasty (TAA) often have symptomatic adjacent joint arthritis and deformity. Adjunctive procedures are frequently indicated in this setting in an attempt to ensure a stable and plantigrade ankle and hindfoot postoperatively. Although subtalar arthrodesis can effectively address a degenerative hindfoot, it may also place abnormal stress on the TAA, leading to premature failure. The objective of this study was to determine the effect of subtalar arthrodesis on TAA and adjacent joint kinematics using cadaveric gait simulation. We hypothesized that differences in ankle and talonavicular joint kinematics would be observed between TAA specimens with and without subtalar arthrodesis. Methods: Three mid-tibia cadaveric specimens (all female, average age at death: 48) with neutral foot alignment and no history of lower extremity trauma or surgery were tested in a robotic gait simulator. Each tibia was secured to a static mounting fixture about a six-degree of freedom robotic platform (Figure 1A). During simulations, a force plate was moved relative to the stationary specimen through an inverse tibial kinematic path based on standardized in vivo data. Salto Talaris total ankle prostheses were implanted (Tornier, Inc., Bloomington, MN) by a foot and ankle fellowship trained orthopaedic surgeon. Gait simulation was then performed. Each specimen then underwent in situ subtalar arthrodesis via fluoroscopically guided screw placement and subsequent gait analysis. The kinematics of TAA and TAA with subtalar arthrodesis during simulated walking were then compared using two-tailed, paired Student’s t-tests with an alpha value set at p = 0.05. Results: Analyses revealed that kinematics differed between specimens with TAA and those with TAA and subtalar arthrodesis (Figure 1B). During mid-stance, less ankle plantarflexion was observed in specimens with TAA and subtalar arthrodesis, as compared to those with isolated TAA. This difference was statistically significant (p < 0.05). With regard to axial motion in the ankle, significantly less external rotation was observed in early and mid-stance in specimens with TAA + subtalar arthrodesis (p < 0.05). Talonavicular kinematics also differed between cohorts (Figure 1B). In early and late stance, significantly decreased inversion was observed in specimens with subtalar arthrodesis (p < 0.05). And in early stance, talonavicular joint adduction was significantly diminished in the TAA + subtalar arthrodesis specimens, as compared to those with isolated TAA (p < 0.05). Conclusion: Via cadaveric gait simulation, our study describes the kinematic effects of subtalar arthrodesis on TAA. When TAA is performed in the setting of subtalar arthrodesis, both ankle sagittal and axial plane motion are altered, as are coronal and axial plane motion in the talonavicular joint. Because current clinical literature remains inconclusive on this relationship, additional work must be performed to better delineate the biomechanical and clinical sequelae of TAA performed with subtalar arthrodesis.

Category: Ankle Arthritis Introduction/Purpose: Ankle arthrodesis is an effective treatment for decreasing pain in patients with end-stage ankle arthritis. However, all patients with an ankle arthrodesis will eventually develop adjacent joint arthritis. The etiology of adjacent joint arthritis after ankle arthrodesis is not fully understood due to the difficulty of investigating these joints in vivo. Cadaveric simulation provides a unique capability of studying intrinsic foot and ankle joint mechanics. The objective of this study was to establish the effect of ankle arthrodesis on adjacent joint kinematics using cadaveric gait simulation. We hypothesized that adjacent joint motion of the hindfoot would increase after ankle arthrodesis. Methods: Four mid-tibia cadaveric specimens were potted and secured to a static mounting fixture about a six-degree of freedom robotic platform.(Figure 1A) The nine extrinsic ankle tendons were isolated and connected to linear actuators instrumented with load cells in series. During simulations, a force plate was moved relative to the stationary specimen through an inverse tibial kinematic path. Three-dimensional ankle and hindfoot kinematics were captured using a motion capture system. After ankle arthrodesis, kinematics were recorded using the same muscle force and kinematic inputs as the intact condition to determine how the hindfoot would behave when simulating normal gait. To assess the effect of ankle arthrodesis during simulated walking on adjacent joint kinematics, pre- and post-arthrodesis kinematics of the subtalar and talonavicular joint were directly compared along the stance phase and differences were assessed using two-tailed, paired Student’s t-tests with an alpha value set at p = 0.05. Results: Subtalar and talonavicular joint plantarflexion was greater during the early phase of stance in the ankle arthrodesis condition.(Figure 1B and 1C). Talonavicular joint motion also demonstrated greater dorsiflexion during late stance following ankle arthrodesis (Figure 1C). Ankle arthrodesis had no detectable effect on axial or coronal plane motion in adjacent joints of the hindfoot. Conclusion: This study reveals that sagittal plane motion in the hindfoot is increased following ankle arthrodesis. These results provide further insight into how motion is redistributed to adjacent joints after arthrodesis during gait. Such compensatory motions may be related to changes in contact mechanics in adjacent joints which can lead to degenerative changes.

Category: Hindfoot Introduction/Purpose: Lateral column lengthening is a powerful procedure utilized to correct the associated abduction deformity in stage II flatfoot deformity; however, prior studies have shown complications of nonunion, graft collapse, and lateral column overload with the Evans osteotomy. The Stepcut Lengthening Calcaneal Osteotomy (SLCO) is a z-lengthening calcaneal osteotomy that can correct midfoot abduction while providing inherent stability by creating a large surface area for bony healing. The goal of our study was to compare outcomes in patients undergoing a SLCO versus an Evans osteotomy. It is our hypothesis that patients following a SLCO would have a decreased incidence of nonunion and lateral overload of the foot, and similar improvement in clinical outcome scores. Methods: All consecutive patients from 2006 to 2013 undergoing stage IIB flatfoot reconstruction from our institution’s Foot & Ankle Registry were identified and included. There were 65 Evans & 79 Stepcut patients with a minimum of two year followup. All patients undergoing flatfoot reconstruction were included regardless of associated procedures which were not significantly different between the groups (Table 1). Deformity correction was assessed using preoperative and postoperative weightbearing radiographs. Healing of the osteotomy was assessed by computed tomography (CT). Clinical outcomes were assessed by the Foot and Ankle Outcomes Score (FAOS) survey which has been validated for flatfoot. Rate of return to the OR was also assessed. Differences in continuous variables between groups were assessed with independent samples t-tests, or Mann-Whitney U tests when non-normally distributed. Differences in categorical variables between groups were assessed with chi-squared and Fisher’s exact tests. An alpha level of 0.05 was deemed statistically significant. Results: The Evans group had a 0.9 mm larger graft size (p < 0.001) than the SLCO Group (Table 2). The SLCO group had greater improvement in talonavicular coverage angle (p < 0.001) and talonavicular incongruency angle (p = 0.023) than the Evans group. The Evans group returned more often for additional surgeries (p = 0.030). While there was improvement in mean FAOS scores in both groups for all subscales, only the mean FAOS score for sports activities (p = 0.012) was statistically better in the SLCO group. Rate of nonunion was not statistically significant (p = 0.086) between groups. There was no occurrence of loss of correction or lack of healing of the main (horizontal) arm of the osteotomy site in the SLCO group. Conclusion: Patients who underwent the SLCO for stage IIb adult-acquired flatfoot deformity demonstrated excellent healing, good correction of deformity, utilized a smaller graft size for correction, and less frequently needed to have a second operation on the involved foot. Additionally when compared to the Evans osteotomy, the SLCO group had comparable improvements in FAOS scores; thus making the SLCO a reasonable alternative for lateral column lengthening

Category: Ankle Arthritis. Introduction/Purpose: Total ankle arthroplasty (TAA) is an effective treatment option for end-stage ankle arthritis. However, with reports on long-term survivorship of current implant designs still anticipated in the literature, current research has focused on assessing prosthetic function and predicting potential failure mechanisms. Cadaveric gait simulation is a valuable tool for investigating the effects of surgical techniques on foot and ankle biomechanics. The objective of this study was to assess the effect of TAA on ankle and hindfoot kinematics using cadaveric gait simulation. We hypothesized that joint motion would be altered by the change in the articular constraint associated with joint replacement. Methods: Three mid-tibia cadaveric specimens were secured to a static mounting fixture about a six-degree of freedom robotic platform. A force plate was moved relative to the stationary specimen through an inverse tibial kinematic path calculated from in vivo data. Target tendon force profiles were applied to the nine extrinsic ankle tendons by linear actuators instrumented with load cells. (Figure 1A). Ankle and hindfoot kinematics were measured from reflective markers attached to bones via surgical pins. TAA was performed using the Salto Talaris prosthesis (Bloomington, MN). After replacing the ankle joint, foot and ankle kinematics were directly measured using the same kinematic inputs and muscle force as the intact condition. To assess the effect of TAA on joint kinematics, pre- and post-TAA motions were directly compared throughout the stance phase, and differences were assessed using two-tailed, paired Student’s t-tests with an alpha value set at p = 0.05. Results: Analyses revealed that ankle joint transverse plane motion was affected by TAA, with significantly greater talar internal rotation during the middle portion of stance after joint replacement (Figure 1B). In contrast, no differences were present in ankle joint sagittal and coronal plane motion between the intact and TAA condition. Dorsiflexion was greater in the subtalar joint after TAA during early stance. Similarly, there was greater dorsiflexion in the talonavicular joint during mid-stance in the TAA condition compared to the intact condition. There were no differences observed in the coronal or axial plane in either the subtalar or talonavicular joint after TAA. Conclusion: This study revealed that the talus underwent greater internal rotation during the weight acceptance portion of gait after TAA. The ankle joint however behaved similarly with respect to sagittal and coronal plane motion throughout stance after TAA. Compensatory motion however was noted in the subtalar and talonavicular joints, with greater dorsiflexion present in both joints during stance after TAA. This abstract represents an early subset of an ongoing study; smaller yet clinically important differences may still be present, and may be detected as more specimens are completed.

Category: Trauma Introduction/Purpose: Ankle fractures are commonly-sustained injuries, and frequently require open reduction internal fixation (ORIF). It is generally a safe and effective surgical procedure, however, as quality-based reimbursement models become increasingly affected by readmissions within thirty days, it is important to determine causes and risk factors for patients to be readmitted after discharge. Methods: Patients that underwent ORIF for ankle fractures were identified from the prospectively-collected American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database from 2013 to 2014. Baseline demographics, comorbidities, and fracture characteristics (open vs. closed, location of fracture such as lateral malleolus, medial malleolus, bimalleolar, or trimalleolar) were determined. Modified Charlson Comorbidity Index (CCI) was used as a measure of overall comorbidity burden. Rates of thirty-day adverse events and readmissions were determined, as well as the causes for readmission. Multivariable logistic regression analyses were performed to identify risk factors significantly associated with having any adverse events and being readmitted within thirty days of surgery. Results: 5,056 ankle ORIF patients were included. 167 (3.3%) were open fractures. The rate of any postoperative adverse event was 5.2%. There were 127 readmissions, with 116 (91.3%) being unplanned readmissions. Of the 116 unplanned readmissions, 49 (42.2%) were for reasons related to the surgery or surgical site, with the most common causes being deep surgical site/hardware infection (12.9%), superficial site infection (11.2%), and wound disruption (6.9%). Most readmissions were for reasons unrelated to the surgical site (51.7%), including cardiac disorders (8.6%), pulmonary disorders (7.8%), and neurologic/psychiatric disorders (6.9%). With multivariable logistic regression, the strongest risk factors for readmission were history of pulmonary disease (Odds Ratio [OR] 2.29), ASA ≥ 3 (OR 2.28), and open fracture (OR 2.04, all p < 0.05). (Figure 1) Conclusion: Postoperative readmissions following ankle fracture ORIF are important to consider in this era of quality-based hospital reimbursement models. In this cohort of 5,056 ankle ORIF cases, 2.5% of patients were readmitted within thirty days, with 51.7% of all unplanned readmissions due to causes unrelated to the surgery or surgical site. This suggests that close medical follow-up with non-orthopaedic providers may be necessary after discharge. To assist clinicians in preoperative risk stratification, predictors of readmission were history of pulmonary disease, increased ASA class, and open fracture. Higher bundled reimbursements may be justified for cases with these risk factors.

Several options exist for the treatment of osteochondral lesions of the talus. Particulated juvenile cartilage allograft transplantation (PJCAT) has become a viable treatment modality for osteochondral lesions of the talus that are not amenable to microfracture or for which microfracture has failed. Arthroscopic placement of this type of graft obviates the need for osteotomy or plafondplasty and does not prevent additional procedures from being performed through an anterior approach. Special instrumentation and setup are not required to perform this procedure. Our arthroscopic technique for placement of particulated juvenile cartilage into osteochondral lesions of the talus is described. Case series and outcomes after arthroscopic ankle PJCAT are currently not reported within the literature; however, it is believed that the outcomes are at least similar to those of open ankle PJCAT.