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Summary: SARS-CoV-2 infection in children typically results in asymptomatic or mild disease. There is a paucity of studies on SARS-CoV-2 antiviral immunity in African children. We investigated SARS-CoV-2-specific T cell responses in 71 unvaccinated asymptomatic South African children who were seropositive or seronegative for SARS-CoV-2. SARS-CoV-2-specific CD4+ T cell responses were detectable in 83% of seropositive and 60% of seronegative children. Although the magnitude of the CD4+ T cell response did not differ significantly between the two groups, their functional profiles were distinct, with SARS-CoV-2 seropositive children exhibiting a higher proportion of polyfunctional T cells compared to their seronegative counterparts. The frequency of SARS-CoV-2-specific CD4+ T cells in seronegative children was associated with the endemic human coronavirus (HCoV) HKU1 IgG response. Overall, the presence of SARS-CoV-2-responding T cells in seronegative children may result from cross-reactivity to endemic coronaviruses and could contribute to the relative protection from disease observed in SARS-CoV-2-infected children.

Category: Ankle Arthritis; Ankle Introduction/Purpose: Revision of failed total ankle replacement (TAR), such as in the setting of implant subsidence, aseptic loosening, or avascular necrosis (AVN) of the talus can be challenging and associated with increased morbidity. As TAR becomes a more commonly performed procedure in the treatment of end-stage ankle arthritis (ESAA), naturally there arises the need for revision options. In this case series, we describe the short-term clinical and radiographic outcomes of using a patient-specific custom 3D-printed total ankle total talus (TATR) prosthesis in the treatment of this unique subset of patients. Methods: 29 patients with ESAA who underwent TATR by a single surgeon at our institution from 2019 to 2022 were retrospectively identified. Average age was 61.3 (range, 39-77) years, with average follow-up of 22.5 (range, 12 to 57) months. All patients were indicated for revision of primary STAR implant (Stryker, Kalamazoo, MI) for failed TAR in the setting of aseptic loosening/subsidence and/or talar AVN. All patients underwent replacement with 3D-printed titanium implants based on preoperative CT analysis (Additive Orthopaedics, Little Silver, NJ). Custom components included a combined total talus and stemmed tibial component through an anterior approach (Figure). Pre- and postoperative patient-reported outcome were assessed using Patient Reported Outcomes Measurement Information System (PROMIS). Pre- and postoperative implant alignment was assessed using medial distal tibial angle (MDTA) and tibiotalar angle (TTA) on anteroposterior, and sagittal tibial angle (STA) on lateral weightbearing plain films. Incidence of revision and reoperations were recorded. Results: At final follow-up, all custom implants were intact without evidence of hardware failure or implant subsidence. There was significant improvement in all six PROMIS domains (Table). Two patients (6.9%) had postoperative complications; one patient underwent open reduction internal fixation of the tibia for a tibial periprosthetic fracture 1 month postoperatively, another patient underwent medial gutter debridement and tarsal tunnel release for recurrent pain 14 months postoperatively. There were no significant differences in pre- to postoperative radiographic coronal or sagittal alignment in terms of MDTA (88.4 vs 88.8), TTA (87.3 vs 88.0), or STA (85.1 vs 85.9). Conclusion: As ankle replacement becomes a more popular surgical treatment for ESAA, there is a growing need to identify durable revision solutions. This study demonstrates the promising utility of custom 3D-printed TATR in the setting of revision TAR. At short-term follow-up, there was significant improvement in pain and physical function, with an acceptable postoperative complication rate. While preliminary, custom 3D-printed TATR offer an alternative solution for a unique subset of patients where there are limited options available for revision following failed primary TAR. Further longer-term follow-up with a larger cohort is underway.

Category: Ankle Arthritis; Ankle Introduction/Purpose: Total ankle arthroplasty (TAA) has surpassed arthrodesis as the gold standard for treatment of end-stage ankle arthritis. The Zimmer Trabecular Metal Total Ankle Implant (Zimmer-Biomet, Warsaw, IN) differs from other newer- generation implants in the transfibular approach, non-mobile-bearing prosthesis, high-molecular-weight polyethylene, curved surface at every interface in the sagittal plane, and shallow resection depth. There is limited mid-term follow-up for this system. Therefore, we sought to report mid-term clinical, functional, and radiographic results we well as complications and survival for patients treated with the transfibular TAA at a minimum of 5-years follow-up. Methods: A retrospective review was performed on patients who underwent primary transfibular TAA by a single surgeon from October 2012 to January 2018. Inclusion criteria was a minimum of 5-years of follow-up with a completed consent for participation in the study and patient-reported outcome measures (PROM). Patient demographics and perioperative data were collected. PROMS included: 12-item Short Form Health Survey (SF-12) physical (PCS) and mental (MCS) component scores; Ankle Osteoarthritis Scale (OAS); and Visual Analog Scale (VAS). Functional outcomes included range of motion (ROM) measured on weightbearing ROM radiographs. Radiographic outcomes included coronal and sagittal alignment. Adverse events and reoperations were reported using the Canadian Orthopedic Foot and Ankle Society (COFAS) Reoperation Coding System (CROCS). Of the consecutive 151 TAAs, 83 (55.0%) ankles are included in this study, evaluated at a mean of 5.8 years clinical and 6.3 years radiographic follow-up. Results: The average age was 60.6 years-old. Preoperative tibiotalar coronal deformity included 27 valgus (10°, range 2-20°) and 25 varus ankles (-9°, range -2--25°), successfully corrected to neutral postoperatively. The postoperative PROMs were: SF-12 PCS: 40.4, SF-12 MCS: 56.0, VAS: 2.3, AOS Pain: 17.0, and AOS Disability: 24.9. Radiographic postoperative tibiopedal ROM was 17.8° dorsiflexion and 21.8° degrees plantarflexion. The overall reoperation rate was 38.6%(n=32) at an average of 28.7 months postoperative. Most common were removal of the fibula hardware (n=21,25.3%) and medial gutter debridement (n=15, 18.1%). There were 3 (3.6%) cases of acute postoperative infection (< 3 months) treated with operative irrigation and debridement but retention of the metal components. There were no cases of septic or aseptic loosening or subsidence. The overall implant survival, defined by retention of the metal components, was 100%. Conclusion: Transfibular TAA is a safe and effective treatment for end-stage ankle arthritis at 5-year mid-term follow-up. This study confirms excellent clinical results including PROMs and ROM as well as radiographic alignment correction and maintenance. The survival rate was 100% for retention of the trabecular metal components. The survival rate to reoperation was 60.7% with patients commonly requiring removal of the fibula hardware or medial gutter debridement. Patients should be counseled on the risk of reoperation preoperatively for postoperative expectation management.

This case involves a healthy male with painful lateral knee pain and snapping after a hyperextension injury. Initially, this was felt to be from a displaced lateral meniscus tear; however, he failed to improve after meniscal debridement. Further workup with an ultrasound and magnetic resonance imaging identified an aberrant biceps femoris anatomy. He was taken to the operating room and the aberrant slip was identified. A tenodesis of the aberrant slip to the biceps femoris was completed. This resolved the patient's pain and snapping, and he was able to return to all activities.

Background: Ankle fractures involving the posterior malleolus (PM) tend to result in inferior clinical outcomes compared to other ankle fractures. However, it is unclear which specific risk factors and fracture characteristics are associated with negative outcomes in these fractures. The aim of this study was to identify risk factors for poor postoperative patient-reported outcomes in patients with fractures involving the PM. Methods: This retrospective cohort study included patients who sustained ankle fractures involving the PM between March 2016 and July 2020 and had preoperative computed tomography (CT) scans. In total, 122 patients were included for analysis. One patient (0.8%) had an isolated PM fracture, 19 (15.6%) had bimalleolar ankle fractures involving the PM, and 102 (83.6%) had trimalleolar fractures. Fracture characteristics including the Lauge-Hansen (LH) and Haraguchi classifications and posterior malleolar fragment size were collected from preoperative CT scans. Patient Reported Outcome Measurement Information System (PROMIS) scores were collected preoperatively and at a minimum of 1 year postoperatively. The association between various demographic and fracture characteristics with postoperative PROMIS scores was assessed. Results: Involvement of more malleoli was associated with worse PROMIS Physical Function ( P = .04), Global Physical Health ( P = .04), and Global Mental Health ( P

Category: Ankle; Other Introduction/Purpose: Periprosthetic joint infection (PJI) is a devastating complication of arthroplasty. The well known PJI risk factors are useful for identifying high-risk patients but would be even more helpful for clinical decision-making if they are converted to a risk assessment scores. The Mayo Prosthetic Joint Infection Risk Score was based on the data of total hip and knee arthroplasty and has not been validated for application for total ankle arthroplasty. Methods: A series of 398 consecutive cases of total ankle arthroplasty, with minimal follow-up of 6 months, was reviewed for Mayo Periprosthetic Joint Infection Risk Score (Mayo score) and PJI. The patients' Mayo scores and PJI was examined by logistic regression. T-test was performed to compare the Mayo score between the non-infected TAA cases and infected cases. Receiver Operating Characteristic (ROC) was used to identify the critical value of Mayo score for total ankle arthroplasty. Results: There were 12 cases of PJI or 3.0% in the series. Of the 398 patients, the Mayo scores were in the range from -4 to 13 (median 2; interquartile range (IQR) 0-4). Preliminary analysis showed that, by logistic regression, the probability of PJI was increased as increases of the Mayo scores (Fig A). The mean Mayo score of the PJI patients (8.6+-1.8) was significantly greater than the rest of the patients (mean Mayo score 1.9+-3.4; p < .0001). ROC analysis showed that, when a Mayo score was greater than 5, the patient has a high probability of PJI (sensitivity = 100%; specificity = 86.9%; Fig B). Conclusion: This study showed a high correlation between the Mayo score and PJI in total ankle arthroplasty, which is the same trend as in total knee and hip arthroplasty. The preliminary results suggest that strategically focusing on the patients, who have a Mayo score > 5, could be a more efficient approach to prevent PJI after total ankle arthroplasty.

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.

IntroductionMultisystem inflammatory syndrome in children (MIS-C) is a severe acute inflammatory reaction to SARS-CoV-2 infection in children. There is a lack of data describing differential expression of immune genes in MIS-C compared to healthy children or those with other inflammatory conditions and how expression changes over time. In this study, we investigated expression of immune-related genes in South African MIS-C patients and controls.MethodsThe cohort included 30 pre-treatment MIS-C cases and 54 healthy non-inflammatory paediatric controls. Other controls included 34 patients with juvenile systemic lupus erythematosus, Kawasaki disease or other inflammatory conditions. Longitudinal post-treatment MIS-C specimens were available at various timepoints. Expression of 80 immune-related genes was determined by real-time quantitative PCR.ResultsA total of 29 differentially expressed genes were identified in pre-treatment MIS-C compared to healthy controls. Up-regulated genes were found to be overrepresented in innate immune pathways including interleukin-1 processing and pyroptosis. Post-treatment follow-up data were available for up to 1,200 hours after first treatment. All down-regulated genes and 17/18 up-regulated genes resolved to normal levels in the timeframe, and all patients clinically recovered. When comparing MIS-C to other febrile conditions, only IL27 expression could differentiate these two groups with high sensitivity and specificity.ConclusionsThese data indicate a unique 29-gene signature of MIS-C in South African children. The up-regulation of interleukin-1 and pyroptosis pathway genes highlights the role of the innate immune system in MIS-C. IL-27 is a potent anti-inflammatory and antiviral cytokine that may distinguish MIS-C from other conditions in our setting.

Category: Hindfoot; Midfoot/Forefoot; Sports Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a condition encompassing multiple interrelated, progressive bony and soft tissue deformities, often requiring surgical correction. Patients are often debilitated, with postoperative goals commonly cited as walking and low-impact activities without pain. However, some patients engage in sports and more rigorous activities. Surgeons may struggle to set expectations after surgery since few studies investigate returns to activity following flatfoot reconstruction and every patient is different. Existing studies are limited by small sample sizes, lack of data of activity-specific data, and cohorts confined to one or two of the many possible concomitant procedures in flatfoot reconstruction. This study aims to provide the first generalizable assessment of returns to sports and physical activity following reconstruction surgery in patients with flexible PCFD. Methods: Patients who underwent reconstructive surgery from February 2016-May 2019 for flexible-stage PCFD were identified by registry review and contacted with IRB approval. 70/119 patients (72/121 feet, 60%) were reached at mean 3.1 (range, 2.0 to 5.4) years post-operatively with mean age 43.5 (range, 18 to 59) years at surgery. Concomitant procedures were noted. Physical activity was evaluated with a previously published questionnaire that assessed participation in 15 sports and activities, allowed patients to list additional activities, and classified activities as high or low-impact. Patients specified postoperative number of sessions per week, session duration, return times to participation and maximal activity, relative pre/postoperative difficulty, and satisfaction with outcome regarding sports. Clinical outcomes were evaluated with Patient-Reported Outcomes Measurement Information System (PROMIS) scores. Multivariable regressions assessed associations between PROMIS domain changes and survey responses and linear models measured association of sports participation with the most performed procedures, controlling for concomitant procedures. Results: Patients experienced significant improvements in all PROMIS domains except Depression and surpassed previously reported minimal clinically important differences for PCFD in Physical Function and Pain Interference scores. Patients reported participation in 21 specific sports and activities (Table 1). Compared to preoperatively, patients rated 16.7% (45/270) of activities as more difficult postoperatively, 33.3% (90/270) as equally difficult, and 50% (135/270) as less difficult. Median return times were 6-9 months for participation in activities and 13-18 months to reach maximum preoperative participation. Patients spent a median 7.6 (range, 0-29.8) hours/week engaged in physical activity. 3% of patients (2/72) were sedentary, 31% (22/72) were moderately active, 28% (20/72), were highly active and 36% (26/72) were extremely active. Improvements in Physical Function ( P =.021), Pain Interference ( P =.001), and Global Physical Health ( P =.001) were associated with increased outcome satisfaction regarding physical activities. No associations were found between procedures performed and any PROMIS domains or return parameters. Conclusion: This is the largest and most comprehensive analysis of patient participation in sports and physical activities following flatfoot reconstruction. Results suggest that flatfoot reconstruction surgery generally results in good returns to physical activity in terms of return time, pre-postoperative difficulty changes, and satisfaction. Some patients reported increased difficulty or inability to return to their preoperative maximum level of participation, indicating that flatfoot reconstructions can lead to some athletic limitations. However, ninety percent of patients reported satisfaction with their surgical outcomes with respect to returns to physical activity, indicating that, for most patients, flatfoot reconstruction provides meaningful relief from debilitation.

Category: Ankle Arthritis; Sports Introduction/Purpose: While osteochondral autograft transplantation (OAT) offers favorable results in most patients with osteochondral lesions of the talus (OLT), some patients continue to experience persistent pain following the procedure. Information regarding the etiology of this pain and outcomes of revision surgery are limited. This study aimed to report results of revision surgery with realignment procedures in patients with failed OAT who demonstrated concomitant malalignment at the distal tibia or hindfoot. Methods: Eight ankles with persistent pain following OAT underwent revision surgery with realignment procedures. All patients underwent primary OAT for treatment of medial OLTs. Patients were divided into two groups based on the main location of deformity; the Supramalleolar realignment group (SRG, five ankles) and the Hindfoot realignment group (HRG, three ankles). No direct procedure was performed on the osteochondral lesion at the time of revision surgery. Ankle and hindfoot alignment were evaluated using six parameters in weightbearing radiographs. Computed tomography (CT) was used to assess for medial gutter narrowing, spur formation, and cyst volume around transplanted osteochondral plug pre-and postoperatively. Clinical outcomes were assessed using foot function index and visual analogue scale. Results: All patients had medial gutter narrowing or spur formation, which are early signs of ankle arthritis. The SRG had varus distal tibial alignment with a median medial distal tibial angle of 85.7 degrees (Interquartile range [IQR], 3.2). The HRG had valgus hindfoot alignment and a lower medial longitudinal arch with a median hindfoot moment arm of 8.4 mm (IQR, 6.1) and a median Meary angle of 11.8 degrees (IQR, 1.4). Spontaneous restoration of the osteochondral lesion was observed after realignment surgery, with cyst volume decreasing from 0.2592cm3 to 0.0873cm3 (p

Background: Many foot pathologies have been associated with foot type. However, the association of first ray hypermobility remains enigmatic. The purpose of this study was to investigate first ray hypermobility among participants with planus and rectus foot types and its influence on static measures of foot structure. Methods: Twenty asymptomatic participants with planus (n = 23 feet) and rectus (n = 17 feet) foot types were enrolled. Several parameters of static foot structure (arch height index, arch height flexibility, first metatarsophalangeal joint flexibility, and first ray mobility) were measured. Participants were further stratified into groups with nonhypermobile (n = 26 feet) and hypermobile (n = 14 feet) first rays. First ray mobility ≥ 8 mm was used to define “first ray hypermobility”. Generalized estimating equations, best-fit regression lines, and stepwise linear regression were used to identify significant differences and predictors between the study variables Results: Overall, 86% of subjects categorized with first ray hypermobility exhibited a planus foot type. Arch height flexibility, weightbearing first ray mobility, and first metatarsophalangeal joint flexibility showed no significant between-group differences. However, weightbearing ray mobility and first metatarsophalangeal joint laxity were associated with partial weightbearing first ray mobility, accounting for 38% of the model variance. Conclusion: The planus foot type was found to be associated with first ray hypermobility. Furthermore, weightbearing first ray mobility and first metatarsophalangeal joint laxity were predictive of partial weightbearing first ray mobility, demonstrating an interaction between the translation and rotational mechanics of the first ray. Clinical Relevance: Association of first ray hypermobility with foot type and first metatarsophalangeal joint flexibility may help understand the sequela to symptomatic pathologies of the foot.

Category: Ankle; Ankle Arthritis; Other Introduction/Purpose: Periprosthetic infection is a devastating complication in total ankle arthroplasty (TAA). Measures that can reduce or eliminate infection occurrence are warranted for further investigation, particularly if they also minimize added costs, operative time or potential adverse effects. There remains insufficient evidence to show definitive benefits or risks associated with use of local antibiotics such as vancomycin for infection prevention. The purpose of this study was to determine the effects of topical vancomycin powder application in TAA and whether it may decrease infection rate in the subacute postoperative period. To our knowledge, this is the first comparative study in a general population undergoing TAA. Methods: A retrospective study was conducted based on a consecutive series of patients who underwent TAA performed by a single senior surgeon. The control group without vancomycin powder was matched to the study group that received application over the implants prior to closure, which was based on when the surgeon transitioned to usage in all patients. Various demographic data for the patients was collected. Only patients with a minimal follow up of 80 days were included in order to capture the perioperative period of infection. Infection rate was based on a definition of deep infection necessitating inpatient hospitalization for IV antibiotics and/or surgical intervention. The associations of various demographic factors and vancomycin application with infection rate were calculated with chi square and odds ratio. Significance level was set to 0.05. Results: A total of 252 patients (n=103 without, and 149 with vancomycin powder) were included in the study. The overall infection rate was 3.2%, which was not correlated with a history of diabetes, BMI, additional concurrent surgery, or age, but was associated with current positive smoking status (p=0.03). The infection rates between the groups that received or did not receive vancomycin powder were not statistically significantly different (2.7% vs 3.9%, respectively, p=0.59). The odds ratio (OR) of infection with vancomycin powder was not statistically significant either, at OR=0.68 (95% CI 0.17-2.81). However, the vancomycin group did have a significantly higher number of patients with previous wound issues (12 vs. 2; p=0.04) and infection (7 vs. 0; p=0.04) as well as concomitant surgeries (81 vs. 41; p=.02). Conclusion: The consequences of periprosthetic TAA infection are substantial, and the risks should be mitigated. Although this study did not detect a statistically significant difference in infection rates between patients who received or did not receive vancomycin powder, there was a trend towards risk reduction by about 30%. In addition, current smoking was found to be significantly associated with higher rates of infection and smoking cessation can serve as another point of intervention. As the complexity of patient factors and indications for performing total ankle arthroplasty expand, vancomycin powder offers a relatively cost-effective, safe, and convenient option to potentially reduce infection.

Category: Other; Ankle; Ankle Arthritis; Bunion; Hindfoot; Midfoot/Forefoot; Sports; Trauma Introduction/Purpose: Fulfilment of patients' expectations following foot and ankle surgery has been previously studied, and shown to be an effective modality in assessing patient-reported outcomes (PROs). While this assessment has been shown to correlate well with patient satisfaction and other validated PROs, the impact of postoperative complications on fulfilment of expectations is unknown. The aim of this study is to therefore investigate the impact of postoperative complications on fulfilment of patients' expectations. Methods: Preoperatively, patients completed a validated Foot and Ankle Expectations Survey consisting of 23 questions encompassing domains including pain, ambulation, daily function, exercise, and shoe wear. At 2 years postoperatively, patients answered how much improvement they received for each item cited preoperatively. A fulfilment proportion (FP) was calculated as the amount of improvement received versus the amount of improvement expected. Chart review was performed to identify patient demographics, comorbidities, pain management, and postoperative complications, which were classified as minor (infection requiring antibiotics) or major (return to OR for revision, deep infection). FP in patients with a complication was compared to patients who did not experience a complication. In addition, the Foot and Ankle Outcomes Score (FAOS), satisfaction, and Delighted-Terrible scale (how they would feel if asked to spend the rest of their life with their current foot/ankle symptom) were collected at final follow-up. Results: Of the 271 patients (mean age 55.4 years, 65% female), 31 (11.4%, mean age 53.6, 58% female) had a postoperative complication: 25 major (19 revisions, 6 deep infections requiring I&D), 4 minor (4 superficial infections requiring antibiotics), and 2 major and minor (revision and superficial infection). Average time from complication to completion of fulfilment survey was 15 (+- 3.6) months. The groups were similar in diagnoses. Complications were associated with significantly worse FP (0.69 +- 0.45 vs 0.86 +- 0.40, p=0.02). Having a complication significantly correlated with worse satisfaction, Delighted-Terrible scale, and FP (p

Category: Ankle; Sports Introduction/Purpose: The diagnosis and treatment of distal tibiofibular syndesmosis (DTFS) injury can be challenging, especially in cases of subtle instability that may be masked on two-dimensional conventional radiographs. Weightbearing computed tomography (WBCT) has recently emerged as a useful diagnostic tool allowing direct assessment of distal tibiofibular widening. Area measurements of the distal tibiofibular incisura assessed one centimeter proximal to the ankle joint have been proposed as an accurate diagnostic tool to differentiate stable and unstable DTFS, however the literature lacks information regarding normal DTFS area measurements in asymptomatic ankles. The purpose of the current study was to examine and report normal threshold values for DTFS area measurements in a cohort of healthy volunteers, assessing the ankles in natural weightbearing position and under external rotation stress. Methods: In this prospective study, we enrolled twenty-five healthy volunteers without a history of DTFS injury or high ankle sprain, previous foot and ankle surgery, or current ankle pain. Study participants underwent bilateral standing non-stress and external rotation stress WBCT scans. On non-stress WBCT scans, subjects stood with feet shoulder width apart in a natural, upright position with body weight evenly distributed. For external rotation stress images, patients were instructed to position their lower extremity in maximal internal rotation while the foot was held in a fixed plantigrade position. The DTFS area (mm 2 ) was semi-automatically quantified on axial-plane WBCT images one centimeter proximal to the apex of the talar dome using dedicated software (Figure 1). Syndesmosis area values were compared between non-stressed and stressed ankles, as well as left and right ankles. Statistical analysis was performed utilizing independent t-tests/Wilcoxon analysis with statistical significance defined as p

Category: Ankle; Other Introduction/Purpose: Peroneal tendon injuries are a common cause of lateral ankle pain and instability. While the use of hamstring autograft has been proposed as a viable surgical option for peroneus brevis reconstruction, reported outcomes with this technique are limited in the literature. We present patient-reported and clinical outcomes for patients who underwent peroneus brevis reconstruction with hamstring autograft. Methods: Thirty-one patients were retrospectively identified who underwent peroneus brevis reconstruction with hamstring autograft for peroneal tendinopathy between February 2016 and May 2019. All patients who had a peroneus brevis reconstruction were included and all concomitant procedures were noted. Patient-Reported Outcomes Measurement Information System (PROMIS) surveys were prospectively collected preoperatively and at a minimum of 1 year postoperatively (average 24.25, range 12-52.70) months. Retrospective chart review was performed to evaluate the incidence of postoperative complications and reoperations at an average of 30.23 (range, 14.62-53.72) months. Results: When evaluating pre and postoperative patient-reported outcome surveys (n=26; 84%), on average patients reported improvement in every PROMIS domain evaluated, with significant improvement in Physical Function (+5.99; p=0.006), Pain Interference (-8.11; p

Category: Bunion Introduction/Purpose: Multiple operative techniques have been developed for hallux valgus with varying success. While correction has been traditionally achieved through open surgical approaches, there has been a growing interest in minimally invasive surgical (MIS) techniques. The purpose of this study was to compare clinical and patient-reported outcomes for patients undergoing hallux valgus correction with Lapidus, Scarf and MIS. Our hypothesis was that while a superior clinical correction would be achieved with open techniques there would be similar patient-reported outcomes among open and MIS techniques. Methods: A total of 257 patients who underwent Lapidus (n=82), Scarf (n=82) or MIS (n=93) hallux valgus correction between January 2017- January 2020 at one of two academic institutions by 1 of 9 foot and ankle-fellowship trained orthopedic surgeons were included in this study. Only 3 of 9 performed MIS correction. The average age at the time of surgery 55.4 (range 14-79). Patients were required to have a minimum baseline and 1-year postoperative Patient-Reported Outcomes Measurement Information Scores (PROMIS) and minimum 3-month clinical follow-up. Retrospective chart review was performed to assess the incidence of postoperative complications and reoperations, with an average clinical follow-up of 8 months. Results: All groups had statistically significant differences between pre- and post-operative measurements of HVA, IMA, DMAA, and tibial sesamoid position (20) (Lapidus n=7 (8.5%), Scarf n=9 (11.0%), MIS n=9 (9.7%)). Conclusion: In the last decade, there has been a growing interest in the use of minimally invasive surgical MIS techniques for the treatment of hallux valgus. When compared with traditional open techniques using Lapidus and Scarf osteotomies MIS presents a safe and effective approach to treating hallux valgus.

Background: To present the inherent and unique challenges associated with utilizing fracture healing as an outcome measure in foot and ankle orthopedics, specifically the statistical methods used in assessing time to union. Methods: In a previously published manuscript assessing the effect of delayed weightbearing on time to union following intramedullary (IM) screw fixation of Jones (Zone 2 fifth metatarsal base) fractures, patients were divided into early weightbearing (EWB, n=20) and delayed weightbearing (DWB, n=21) cohorts (within or beyond 2 weeks, respectively). Time to union was determined and compared between the 2 cohorts using cumulative link model analysis, with delayed union (12.5 weeks) defined from established literature. Results: Cumulative link model analysis demonstrated no significant differences in time to union (EWB: 25% by 6th week, 55% by 12th week; DWB: 33% by 6th week, 43% by 12th week; P = .819) or delayed unions (EWB, 20% vs DWB, 24%; P > .999). Conclusion: Our analysis using cumulative link models, or ordinal regression, in the statistical analysis of time to union, determined that that early weightbearing following IM screw fixation in Jones fractures appeared to be safe without delaying fracture healing. This statistical approach can be considered when describing a continuous outcome captured by infrequent observations.

This case report chronicles the treatment of a case of plantar fasciitis with acupuncture and tui na for more than six clinic visits. The patient was a 41-year-old female with plantar fasciitis for two months. A variety of acupuncture and electroacupuncture protocols were used at first, with no benefit. After the fourth and fifth visits, however, the patient experienced total relief of pain and a significant reduction in stiffness that persisted through her final visit two weeks later. These later treatments included the yuan-luo (origin-connecting) acupuncture point pair KI 3 and BL 58, which is one possible explanation for their effectiveness. The yuan-luo pair is a classical point combination with much theory behind it, yet no studies have been published regarding its practical uses in clinic. This case is an example of one practical application of the pair; further examples are needed. Keywords: acupuncture, electroacupuncture, origin connecting, plantar fasciitis, plantar heel pain, yuan-luo

The risk of progression from Mycobacterium tuberculosis (M.tb) infection to active tuberculosis (TB) disease varies markedly with age. TB disease is significantly less likely in pre-adolescent children above 4 years of age than in very young children or post-pubescent adolescents and young adults. We hypothesized that pro-inflammatory responses to M.tb in pre-adolescent children are either less pronounced or more regulated, than in young adults. Inflammatory and antimicrobial mediators, measured by microfluidic RT-qPCR and protein bead arrays, or by analyzing published microarray data from TB patients and controls, were compared in pre-adolescent children and adults. Multivariate analysis revealed that M.tb-uninfected 8-year-old children had lower levels of myeloid-associated pro-inflammatory mediators than uninfected 18-year-old young adults. Relative to uninfected children, those with M.tb-infection had higher levels of similar myeloid inflammatory responses. These inflammatory mediators were also expressed after in vitro stimulation of whole blood from uninfected children with live M.tb. Our findings suggest that myeloid inflammation is intrinsically lower in pre-pubescent children than in young adults. The lower or more regulated pro-inflammatory responses may play a role in the lower risk of TB disease in this age group.

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: Hindfoot; Other Introduction/Purpose: Due to the nature of the medial displacement calcaneal osteotomy (MDCO), bony step-off at the osteotomy site is inevitable and can lead to lateral prominence pain. Theoretically, this bony prominence can lead to irritation of the peroneal tendon, sural nerve, and overlying skin resulting in pain and discomfort. While these symptoms have been loosely described in the literature, the incidence and prevention are largely unexplored. The purpose of this study is to investigate the incidence of lateral prominence pain after MDCO as well as the efficacy of a leveling procedure (LP) as a preventive technique. Methods: We retrospectively identified 175 feet in 160 patients who underwent MDCO from 2016 to 2018. Of the 175 feet, 102 underwent MDCO with LP, and 73 without LP. LP was performed after calcaneal fixation by flattening the residual bony prominence using rongeur and bone impactor (Figure 1). Lateral prominence symptoms were defined as pain present at 12 month follow-up after MDCO, either 1) over the lateral prominence on direct contact with the floor or footwear, or 2) associated with callus formation over the osteotomy site due to continued irritation. The overall incidence of lateral prominence symptoms after MDCO and the incidence with or without LP were investigated. The relationship between the amount of calcaneal displacement and the occurrence of lateral prominence pain with or without LP was also analyzed. Results: The overall incidence of lateral prominence was 12.6% (22 of 175): 4.9% (5 of 102) in patients who underwent LP and 23.3% (17 of 73) in patients who did not undergo LP (p

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: Midfoot/Forefoot; Other Introduction/Purpose: Coalition of the naviculo-medial cuneiform joint (NCJ) is a relatively rare condition among the tarsal bone coalitions. Thus, optimal treatment is still largely unknown. There is a paucity of literature, with few cases documenting arthrodesis of the NCJ in adults with varied outcomes. As the NCJ contributes to the majority of motion along the medial column of the foot, arthrodesis of the joint may cause excessive stress on adjacent joints. Furthermore, the nonunion rate of NCJ is reportedly high, ranging from 3 to 15%. The purpose of this study was to report the outcomes of simple coalition bar excision in patients with NCJ coalition. Additionally, we investigated preoperative abnormal conditions around the NCJ using weight bearing computed tomography (WBCT). Methods: We retrospectively identified 21 feet in 18 prospectively followed patients from 2010 to 2018 who underwent simple coalition bar excision of NCJ in our institution. Chart review was performed to retrieve demographic data of the patients, clinical presentation findings, and concomitant procedures with coalition bar excision. Radiographically, the location and morphological pattern of the coalition were analyzed. Several angular parameters including medial arch sag angle (MASA) were measured on weightbearing x-rays to see if there are any angular collapse at NCJ after coalition bar excision (Figure 1). The existence of abnormal conditions adjacent to the NCJ such as arthritis of the first and second tarsometatarsal joint (TMTJ) and talonavicular joint (TNJ) were assessed using WBCT (n=17). Clinically, pre- and postoperative visual analogue scale (VAS) and foot function index (FFI) were compared to assess for improvement in patient-reported outcomes. Results: The mean age of the patients was 30.9 years (range, 16-62) and the follow-up was 15.9 months (range, 12-24). Majority of the patient had fibrous coalition at the plantar-medial aspect and only one patient had bony coalition. The morphology of fibrous coalition was classified as irregular (n=8), cystic (n=1), and combined (n=11) based on CT findings. Intraoperatively, the motion of the NCJ was identified in every patient after coalition bar excision. WBCT revealed 15 feet (71.4%) having at least one abnormal finding around the NCJ (First TMTJ plantar gap; n=10, second TMTJ narrowing; n=9, first TMTJ spur & irregularity; n=2, TNJ spur; n=1). Pre- and postoperative MASA did not change significantly (p=0.932). There was significant improvement in VAS and FFI at final follow-up (p

Category: Other Introduction/Purpose: Fulfillment of patients’ expectations following foot and ankle surgery has been previously studied and validated in assessing patient-reported outcomes (PROs). While this assessment has been shown to correlate well with patient satisfaction and PROs, the impact of postoperative complications on fulfillment of expectations is unknown. The aim of this study is to therefore investigate the impact of postoperative complications on fulfillment of patients’ expectations. Methods: Preoperatively, patients completed a validated Foot and Ankle expectations survey consisting of 23 questions encompassing domains including pain, ambulation, daily function, exercise, and shoe wear. At 2 years postoperatively, patients answered how much improvement they received for each item cited preoperatively. A fulfillment proportion (FP) was calculated as the amount of improvement received versus the amount of improvement expected. The FP ranges from 0 (no expectations fulfilled), between 0 and 1 (expectations partially fulfilled), 1 (expectations met), to greater than 1 (expectations surpassed). In addition, patient-reported outcomes (FAOS), satisfaction, and Delighted-Terrible scale (how they would feel if asked to spend the rest of their life with their current foot/ankle symptom) were collected at final follow-up. Chart review was performed to identify patient demographics, comorbidities, pain management, and postoperative complications, which were classified as minor (infection requiring antibiotics) or major (unplanned return to OR, reoperation, or revision). Results: Of the 271 patients (mean age 55.4 years, 65% female), 31 (11.4%, mean age 53.6, 58% female) had a postoperative complication; 27 major (17 revisions, 10 removal of hardware due to pain/infection) and 6 minor (6 superficial infections requiring antibiotics). Complications were associated with significantly worse FP (0.69 +- 0.45 vs 0.86 +- 0.40, p=0.02). Average time from complication to completion of fulfillment survey was 15 (+-3.6) months. Having a complication significantly correlated with worse satisfaction, Delighted-Terrible scale, and FP (p

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Surgical correction of the collapsing flatfoot deformity has been well studied in the literature, with the average patient being a female in her 50s. While reconstruction of the flexible, symptomatic flatfoot in children and adolescents has been described, assessment of outcomes across age groups is limited. Therefore, the purpose of our study is to compare the clinical and radiographic outcomes in younger patients 30 years or less undergoing flatfoot reconstruction with that of older patients. In addition, the procedures performed for reconstruction and the incidence of subsequent reoperations were compared between the two groups. Methods: Ninety-four feet (51 left, 43 right) in 87 patients who underwent reconstruction for flexible collapsing flatfoot deformity were divided into 2 groups based on age: 30 years (n=72). Exclusion criteria included tarsal coalition or neuromuscular disease. Average age and BMI was 20.8 years (range, 13 to 30) and 26.8 (range, 18 to 38) in the younger cohort, and 57.5 years (range, 35 to 81) and 29.8 (range, 18 to 46) in the older cohort. Preoperative and minimum 2-year postoperative PROMIS scores were compared. Average follow-up was 30.6 and 27 months in the younger and older cohorts, respectively. We assessed five radiographic parameters both preoperatively and postoperatively, including talonavicular (TN) coverage angle, lateral talo-first metatarsal angle (Meary’s), lateral talocalcaneal angle, calcaneal pitch, and hindfoot moment arm (HMA). Operative reports and hospital records were reviewed to compare procedures performed for reconstruction as well as subsequent reoperations. Results: Younger patients demonstrated significant preoperative to postoperative improvements in Physical Function (p=0.01), Pain Interference (p

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: Bunion; Other Introduction/Purpose: Cone Beam Weight Bearing CT (WBCT) is gaining traction, particularly in the foot and ankle, due to the ability to perform natural stance weight bearing 3D scans. However, the resulting wealth of 3D data renders daily clinical use time consuming. Therefore, reliable automatic measurements are indispensable in order to make best use of the technology. The aim of this study was to evaluate a beta-version WBCT artificial intelligence (AI) automatic measurement system for the M1-M2 intermetatarsal angle (IMA), which is applicable in the absence of metallic hardware in the foot and ankle. We hypothesized that automatic measurements would correlate well with human measurements, and that software reproducibility would be better and close to perfect compared to manual measurements. Methods: In this retrospective case-control study, 90 feet were included from patients who underwent WBCT scans during routine follow up: 44 feet (90.9% female, mean age 54 years) with symptomatic hallux valgus (HV), 46 controls (76.1% female, mean age 49 years). Patients were excluded if they had history of surgery or trauma involving the first or second metatarsals, hallux rigidus, or presence of metal in their foot/ankle. IMA was measured manually on Digitally Reconstructed Radiographs (DRR IMA) and automatically with AI software producing auto 2D (ground plane projection) and 3D (multiplanar) measurements. Each IMA DRR was measured by two independent raters twice to calculate intraclass correlation coefficients (ICCs). To assess intra- software reliability, AI software measurements were made twice on each dataset. Manual and automatic measurements were compared between HV and control groups. Failures of the AI software to produce a measurement were recorded. Results: Mean values for controls were 8.6° +-1.8° (range, 5°-14°) for the manually measured DRR IMA, 9.3° +-2.8° (range, 3°- 17°) for auto 2D, and 9.2° +-2.6° (range, 3°-16°) for auto 3D IMA measurements. Compared to controls, HV patients demonstrated significantly increased IMA (p

Category: Midfoot/Forefoot; Other Introduction/Purpose: Severe adult-acquired flatfoot deformity (AAFD) is often associated with painful medial column collapse at the naviculocuneiform (NC) joint. The purpose of this study was to examine the role of first tarsometatarsal (1st TMT) fusion combined with subtalar fusion in correcting deformity at this joint. Methods: We retrospectively analyzed 40 patients (41 feet) who underwent 1st TMT and subtalar (ST) fusion as part of a flatfoot reconstructive procedure. We assessed six radiographic parameters both preoperatively and at a minimum of 6 months postoperatively, including talonavicular (TN) coverage angle, lateral talo-first metatarsal angle, lateral talocalcaneal angle, calcaneal pitch, hindfoot moment arm, and a newly defined navicular-cuneiform incongruency angle (NCIA). Patient-Reported Outcomes Measurement Information System (PROMIS) clinical outcomes were assessed preoperatively and at a minimum 1 year follow-up. Results: The NCIA demonstrated excellent interobserver reliability, with no significant change between pre- and postoperative measurements. All other radiographic parameters, except calcaneal pitch, demonstrated statistically significant improvement postoperatively (p

Category: Ankle; Ankle Arthritis; Arthroscopy; Basic Sciences/Biologics; Bunion; Diabetes; Hindfoot; Lesser Toes; Midfoot/Forefoot; Sports; Trauma; Other Introduction/Purpose: This study aims to compare a novel opioid prescribing protocol aimed at reducing the number of opioid pills prescribed and consumed with an established, previously published protocol for foot and ankle surgery. We hypothesized that patients in the novel group would consume fewer opioids and report similar satisfaction with pain management compared with the established group. Methods: This study is a single center prospective study of 59 patients undergoing foot and ankle surgery who received a novel opioid prescribing protocol used by the senior author. Preoperatively, patients were counseled on the expectations of pain after surgery, received a take home pamphlet, and were prescribed opioids based on a sliding scale of procedures designated as minor (0-5 pills), moderate (5-10 pills) or major (15-20 pills). These patients were then compared to 84 patients from a previous prospective study from the same institution who received an opioid prescribing protocol with a maximum of 40-60 opioid pills. Patients were excluded if they used opioids or muscle relaxants preoperatively or had a known history of a substance use disorder. Patients completed surveys postoperatively for eight weeks reporting pain level, number of opioid pills consumed, refill requests, and satisfaction with their pain management plan. Results: There was a significant difference (p< 0.001) in mean pills consumed between the novel and established prescribing protocols at all time points (Table 1). During the entire postoperative period patients in the novel group had taken 21% of their prescribed pills compared to 40% in the established group (p=0.03). Patients had comparable levels of pain throughout the study (p>0.05 at POD 3, POD 7 and POD 14) and only differed significantly at POD 56 (p=0.005). Patients in the novel group did not request any refills, whereas patients in the established group requested a total of 9 refills over the course of the study. Conclusion: Patients receiving fewer opioid medications, along with preoperative coaching and take home materials, achieved equivalent analgesic effect when compared to patients receiving approximately double the amount of opioids. This study demonstrates that a sliding scale protocol with a maximum prescription of 20 opioid pills provides appropriate pain relief for most patients. This study confirms that patients on average take far fewer opioid pills than prescribed, and likely an even more limited prescribing protocol would be adequate for the majority of patients. This novel prescribing protocol ensures less opioids are both consumed and leftover for potential diversion in the community.

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Lapidus procedure and Scarf osteotomy are indicated for treatment of mild to moderate hallux valgus. Advantages of modified Lapidus procedure include ability to address severe deformity, first tarsometatarsal arthritis, and first ray hypermobility. Advantages of Scarf osteotomy include greater correction of the distal metatarsal articular angle (DMAA) and greater fixation stability than other techniques. Both procedures have shown good radiographic and clinical outcomes; however, no prior studies have compared these outcomes between the procedures. The aim of this study was to compare clinical and radiographic outcomes between patients with hallux valgus treated with the modified Lapidus procedure or Scarf osteotomy. Methods: This retrospective cohort study included patients treated by one of seven fellowship-trained foot and ankle surgeons were identified. Inclusion criteria were age greater than 18 years, primary modified Lapidus procedure or Scarf osteotomy for hallux valgus, minimum 1-year postoperative PROMIS scores, and minimum 3-month postoperative radiographs. Revision cases were excluded. Clinical outcomes were assessed using six PROMIS domains: Pain Interference, Pain Intensity, Physical Function, Global Mental Health, Global Physical Health, and Depression. Pre- and postoperative radiographic parameters were measured on AP (HVA, IMA, DMAA, tibial sesamoid position), and lateral (talo-1st-metatarsal angle (Meary’s), Horton index, Seiberg index, sagittal IMA) x-rays. Statistical analysis utilized targeted maximum likelihood estimation controls for confounding of bunion severity by including covariates for baseline HVA and IMA. Statistics were also analyzed in a restricted cohort of mild to moderate severity bunions (HVA

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: Hindfoot; Other Introduction/Purpose: Medial displacement calcaneal osteotomy (MDCO) is a commonly performed procedure in flatfoot reconstruction. Fixation is often achieved with screws due to its ability to compress across the osteotomy site. Screws are placed via a free-handed technique without direct fluoroscopic visualization, due to difficulty attaining a simultaneous axial calcaneal view. In addition, the posterior calcaneal tuber translates medially after displacement, resulting in altered anatomical geometry. It is therefore important to establish a reliable external bony landmark when performing free-handed interfragmentary fixation in order to avoid potential screw-related complications and to provide better surgical technique and fixation. The purposes of this study are to validate a new external bony landmark and to establish the appropriate trajectory and screw length for free-hand screw fixation in MDCO. Methods: A total of 84 postoperative computed tomography (CT) scans of MDCO in 70 patients were analyzed. The images were reconstructed using a 3-dimensional simulation program (Vworks 4.0, Cybermed). Virtual screw insertion was simulated by aiming towards two bony landmarks: the base of the 5th metatarsal in the axial plane, and the sinus tarsi in the sagittal plane (Figure 1). A grading system was also utilized to classify scenarios in which the screw breached the distal cortical wall: Grade 1 was defined as contact between the virtual screw and the cortex, Grade 2 as the screw approaching the outer margin of the cortex, and Grade 3 as the screw penetrating the outer cortex. The trajectory angle between the screw and the osteotomy, as well as the screw size, were also measured. Results: The average age of patients was 24.5 (range, 19 to 53), and 100% were males. The average displacement of the posterior calcaneal fragment was 7.3+-1.5 mm (range, 3.9 to 13.8). Among the 84 virtual screws, only five (6.0%) breached the medial cortical wall of the osteotomized calcaneus. All medial breaches were Grade 1. None of the virtual screws breached the lateral cortical wall. Mean trajectory angle between the virtual screw and the osteotomy site was 74.9+-6.7˚ (range, 60.0 to 89.8˚). In the perioperative data, estimated maximum screw length by simulation was 55.6+-4.4 mm (range, 50 to 65). Conclusion: Our results suggest that the optimal trajectory of free-handed screw placement can be determined through simulation of calcaneal interfragmentary screw insertion using postoperative CT imaging. Using this simulation technology, we determined a trajectory towards the sinus tarsi on the sagittal plane and the base of the 5th metatarsal on the axial plane to be a reliable external bony landmark for placement of screws in MDCO. These promising results have potential implications in achieving better fixation as well as improving union rates and operative outcomes.

Category: Ankle; Hindfoot; Other Introduction/Purpose: Adult acquired flatfoot deformity (AAFD) is a complex deformity. Previous work has demonstrated correlation between postoperative foot alignment and patient-reported outcomes. While this work has provided essential targets for surgeons performing flatfoot reconstruction, there is an absence of data that would enable surgeons to predict which patients are likely to have greater or less improvement after surgery based on their preoperative deformity. Conventional radiographs alone may not provide enough detail to isolate individual elements of the deformity. Weightbearing CT (WBCT) allows for far more precise analysis in this regard. We hypothesized that there would be a set of parameters defining preoperative alignment on WBCT that would predict which patients are at risk for a lower magnitude of postoperative improvement in patient-reported outcomes (PROs). Methods: In this retrospective IRB-approved study, patients that underwent surgical flatfoot reconstruction after having a preoperative standing WBCT were identified. Preoperative WBCT images were evaluated by two independent/blinded observers. Multiple parameters related to preoperative alignment and AAFD severity were measured in the sagittal, coronal and transverse planes. Parameters measured included talus-first metatarsal angle; distances between the floor and the navicular, medial cuneiform and cuboid; subtalar joint horizontal angle; superior talar - inferior talar angle; subtalar joint subluxation; talonavicular uncoverage angle; hindfoot moment arm (HMA); and foot and ankle offset (FAO). Prospectively collected data regarding preoperative and postoperative PROs was evaluated. Six PROs components were assessed: physical function; pain interference, pain intensity, global mental health, global physical health and depression. Multivariate regression analysis and a partition prediction model were used to assess the correlation between preoperative alignment and improvement in PROs. P-values of less than 0.05 were considered significant. Results: A total of 51 patients with a preoperative WBCT and postoperative PROs scores were identified and included. Demographic data is shown in Table 1. Multivariate regression analysis demonstrated that preoperative alignment significantly correlated with improvement in three out six components of PROs: pain interference, pain intensity and global mental health. The strongest predictor of improvement in PROMIS physical function t-score was medial cuneiform to floor distance, for pain interference t-score: cuboid to floor distance, for pain intensity: subtalar joint subluxation, for depression t-score: superior talar - inferior talar angle, and for global physical and mental health t-scores: sagittal talus-first metatarsal angle. Conclusion: Our analysis yielded readily identifiable cutoffs for WBCT measurements, where values above or below were correlated with significant differences in the magnitude of PRO score change. Interestingly, measures of sagittal plane collapse and hindfoot valgus were the most predictive of score changes. This data provides useful information for surgeons counseling patients prior to flatfoot reconstruction. Future work using this data to develop prediction models for postoperative outcomes would be valuable, as would studies using WBCT to evaluate the relationship between postoperative corrected alignment and PROs. Complete results are shown in the attached Table.

Category: Hindfoot; Ankle; Midfoot/Forefoot Introduction/Purpose: Multiple surgical techniques are used in the correction of Adult Acquired Flatfoot Deformity (AAFD). Assessment of the efficacy of a surgical treatment in the correction of the deformity is usually performed by clinical evaluation and conventional radiographic imaging. Weightbearing CT (WBCT) allows a more reliable and multiplanar evaluation of AAFD. The Foot and Ankle Offset (FAO) is a WBCT biometric semi-automatic measurement that gauges the relative positioning between the foot tripod and the center of the ankle joint. This study aimed to investigate the efficacy of surgical treatment in correcting AAFD, comparing preoperative and postoperative FAO measurements. We hypothesized that surgical treatment would provide significant correction of the deformity, centering the tripod of the foot underneath the ankle joint. Methods: In this prospective comparative study, 21 adult patients (22 feet) with flexible AAFD were included, mean age 55 (range, 23-81) years, 13 females and eight males. Patients underwent preoperative and postoperative standing WBCT examination. Three-dimensional coordinates (X, Y and Z planes) of the foot tripod (weightbearing point of the first and fifth metatarsals and calcaneal tuberosity) and center of the ankle (apex of the talar dome) were harvested by two independent and blinded observers. The FAO was automatically calculated from the harvested 3D coordinates by dedicated software. Data regarding the surgical technique used was recorded. Patient Reported Outcomes (PROs) were collected preoperatively and postoperatively at a mean follow-up of 22 (range, 8-36) months. Pre and postoperative FAO measurements were compared by paired T-tests. Multivariate analysis was used to assess the influence of surgical procedures in the amount of FAO correction. P-values of less than 0.05 were considered significant. Results: We found excellent intra (0.98) and interobserver reliability (0.96) for FAO measurements. The mean preoperative FAO was 10.4 (95% CI, 8.5 to 12.1). There was a significant correction of the deformity postoperatively (p

Category: Lesser Toes; Other Introduction/Purpose: Lesser toe metatarsal phalangeal (MTP) joint pathology presents a challenge for surgical treatment. Recently, synthetic cartilage implants have been shown to be safe and efficacious in treating hallux ridigus, offering pain relief while preserving motion at the MTP joint. At our institution, metatarsophalangeal joint arthroplasty using a polyvinyl alcohol (PVA) hydrogel implant has been utilized in the 2nd and 3rd MTP joints for advanced arthritis, failed management of Freiberg’s infraction, and osteochondral defects. We present a case series describing the clinical outcomes of 12 patients following PVA implantation of the 2nd or 3rd MTP. Methods: We retrospectively identified 12 consecutive patients (13 joints) who underwent PVA hydrogel implantation of the 2nd (n=12) or 3rd (n=1) metatarsal head between 2017 and 2019. PVA implant was indicated for advanced arthritis in 6 patients (7 joints), Freiberg’s infraction in 4 patients, and osteochondral defect in 2 patients. Average age was 51 years (range, 20-67), with 100% females. Patient-reported outcomes measurement information system (PROMIS) scores were collected preoperatively and at latest follow-up, with an average follow-up of 20.4 months (range, 8.3 to 29.2). Retrospective chart review was performed to evaluate postoperative complications, including need for revision, implant removal, and persistent pain. Results: Overall, patients demonstrated mean improvement in all PROMIS domains, with a significant improvement in Pain Intensity of 11.9 points (p=0.03) postoperatively. A total of 4 postoperative complications occurred in the 12 patients: one case of AVN at 2 years postoperatively, one revision with removal of the implant and bone grafting of the second metatarsal head at 1 year postoperatively, one periprosthetic fracture at 9 months postoperatively, and one recurrence of pain requiring ultrasound- guided injection at 7 months postoperatively. Three additional patients reported persistent pain postoperatively. Conclusion: This study represents the largest case series to date evaluating the use of PVA hydrogel implant in the surgical correction of lesser toe MTP joint pathology. While the PVA implant presents a viable option in the setting of advanced arthritis, Freiberg’s infraction, and certain osteochondral defects, it is not without complications. The specific indications for use of the PVA implant should be carefully considered before implantation.

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: The accessory navicular is often considered to be related to flatfoot deformity. While the Kidner procedure is commonly utilized in treating painful accessory navicular, its ability to correct flatfoot deformity is debated. Patients may also have recurrent pain due to increased tension of the posterior tibial tendon (PTT) in the setting of an uncorrected flatfoot. In the literature, both PTT lengthening and tendon transfer are techniques described to address this issue with varying success and outcomes. Because medial displacement calcaneal osteotomy (MDCO) is a powerful procedure capable of reducing tension of the medial column and correcting hindfoot valgus deformity, we investigated its use in addressing these symptoms. We report outcomes of a novel use of MDCO in treating patients with recurrent pain following Kidner procedure. Methods: We retrospectively identified 21 patients who underwent MDCO for recurrent pain after Kidner procedure at our institution. MDCO was indicated when patients failed to perform single heel raise due to pain at the PTT attachment site at minimum 6 months following index surgery. Pre- and postoperative radiographic parameters were measured: lateral talo-1st metatarsal angle (Meary’s), talonavicular coverage angle (TNC), calcaneal pitch (CP), and hindfoot moment arm (HMA). Using previously validated cut-offs in describing flatfoot deformity, a Meary’s angle less than -4 degrees was considered a flattened arch, and a HMA more than 3.2mm was considered a valgus heel deformity. Measurements were also performed in x-rays of the contralateral foot to determine whether foot deformity in the involved foot was attributed to Kidner procedure or a preexisting deformity. Pre- and postoperative visual analogue scale (VAS) and FAOS outcome scores were compared to assess for improvement in patient-reported outcomes. Results: The mean age was 25.7 years (range, 21-49) and the mean follow-up was 20.1 months (range, 14-26). The average time from the index surgery was 7.3 months (range, 6-10). Average size of the accessory navicular before excision was 11 mm (range, 4.6-18.3). Concomitant procedures included medial head gastrocnemius recession (n=11), plantarflexion osteotomy of first metatarsal bone (n=1), and talocalcaneal coalition excision (n=1). Radiographically, 12 patients (57%) had a flattened arch and all patients (100%) had heel valgus deformity. All radiographic parameters except Meary’s angle (p=0.885) improved postoperatively. Contralateral radiographs revealed that fifteen patients (71%) had a flattened arch, and 19 patients (90%) had heel valgus deformity. There were no differences between both sides. VAS and FAOS improved significantly (p

Category: Midfoot/Forefoot; Other Introduction/Purpose: In 2016, the US Food and Drug Administration (FDA) approved the use of a polvinvyl alcohol (PVA) hydrogel implant (Cartiva, Elmsford, NY) for surgical treatment of hallux rigidus, or degenerative arthritis of the first metatarsophalangeal (1st MTP) joint. While studies have demonstrated the safety and usability of PVA implant, clinical outcomes following hemiarthroplasty with the PVA have not yet been compared to that of traditional joint-preserving procedures such as cheilectomy with Moberg osteotomy in the treatment of hallux rigidus. The purpose of this study is to compare patient-reported outcomes and postoperative complications between PVA hemiarthroplasty and cheilectomy with Moberg osteotomy, with the hypothesis that the addition of PVA would result in superior clinical outcomes. Methods: Patients were retrospectively identified who underwent hallux rigidus correction by one of seven Foot and Ankle fellowship-trained orthopaedic surgeons between March 2016 and November 2018. Out of 162 patients, a total of 133 patients constituted our study cohort after excluding patients with insufficient follow-up. Of the 133, 60 patients (mean age 57.2 years) were treated with combination PVA, cheilectomy, and Moberg osteotomy (PCM) and 73 patients (mean age 54.1) were treated with cheilectomy and Moberg (CM) alone. Both preoperative as well as minimum 1-year postoperative patient-reported outcome scores (PROMIS) were compared between the two cohorts. Chart review was performed to compare rates of revision and complications. Results: Average time to follow-up was 14.5 months for PCM and 15.6 for CM groups. Both PCM and CM cohorts demonstrated significant improvement in PROMIS scores, with the CM group demonstrating significantly greater increase in Physical Function (7.14 +- 8.48 vs 3.58 +- 6.24, p=0.01). While preoperative scores were comparable, postoperatively the CM group had a significantly higher average Physical Function (51.8 +- 8.7 vs 48.8 +- 8.0, p=0.04) and lower Pain Intensity (39.9 +- 8.3 vs 43.4 +- 8.7, p=0.02). There were 2 cases of revision with re-implantation and 1 case of conversion to arthrodesis in the PCM group. There was 1 case of conversion to PVA in the CM group. Three patients who underwent PCM had a documented postoperative infection requiring antibiotics. Conclusion: Our data suggests that the addition of polyvinyl alcohol implant in the treatment of hallux rigidus results in significant improvement in patient-reported outcomes. However, patient-reported physical function may not be up to par at minimum 1-year follow-up compared to cheilectomy and Moberg osteotomy alone. In addition, while incidence was low in our cohort, revision of the implant as well as conversion to arthrodesis remain possible complications of PVA. Therefore, we believe that proper patient selection is recommended when considering surgical treatment options for hallux rigidus.

Background: Active participation in patients’ own care is essential for success after Lapidus procedure. Poor health literacy, comprehension, and retention of patient instructions may be correlated with patient participation. Currently, there is no objective measure of how well patients internalize and retain instructions before and after a Lapidus procedure. We performed this study to assess how much of the information given to patients preoperatively was able to be recalled at the first postoperative visit. Methods: All patients between ages 18 and 88 years undergoing a Lapidus procedure for hallux valgus by the senior author between June 2016 and July 2018 were considered eligible for inclusion. Patients were excluded if they had a history of previous bunion surgery or if the procedure was part of a flatfoot reconstruction. Patients were given written and verbal instructions at the preoperative visit. Demographic and comprehension surveys were administered at their first visit approximately 2 weeks postoperatively. A total of 50 patients, of which 42 (84%) were female and 43 (86%) had a bachelor’s degree or higher, were enrolled. Results: Mean overall score on the comprehension survey was 6.2/8 (±1.2), mean procedure subscore was 1.8/3 (±0.64), and mean postoperative protocol subscore was 4.4/5 (±0.8). The most frequently missed question asked patients to identify the joint fused in the procedure. Conclusion: Although comprehension and retention of instructions given preoperatively was quite high in our well-educated cohort, our findings highlight the importance of delivering clear instructions preoperatively and reinforcing these instructions often. Level of Evidence: Level II, prospective cohort study.

Background: Operative correction of flatfoot deformity has been well studied in the older population. There is a subset of younger patients without congenital foot deformity that also develop a collapsing flatfoot. However, assessment of outcomes across age groups is limited, especially in the young demographic. The purpose of our study was to compare operative outcomes of flatfoot reconstruction between these 2 age groups. Methods: Seventy-six feet (41 left, 35 right) in 71 patients who underwent flexible flatfoot reconstruction were divided into 2 groups based on age: ≤30 years (n = 22) and >30 years (n = 54). Exclusion criteria included congenital causes of flatfoot (tarsal coalition, vertical talus, overcorrected clubfoot). Average age was 20.8 years (range, 14-30) and 55.4 years (range, 35-74) in the younger and older cohorts, respectively. Preoperative and minimum 2-year postoperative Patient-Reported Outcomes Measurement Information Systems (PROMIS) scores were compared. Five radiographic parameters were assessed pre- and postoperatively: talonavicular coverage angle, lateral talo–first metatarsal angle, lateral talocalcaneal angle, calcaneal pitch, and hindfoot moment arm. Procedures performed and incidence of minor (removal of symptomatic hardware) and major (revision) reoperations were compared. Results: Younger patients were less likely to undergo flexor digitorum longus transfer, first tarsometatarsal fusion, spring ligament repair, and posterior tibial tendon repair (all P < .05). Both younger and older cohorts demonstrated significant improvement in multiple PROMIS domains at an average follow-up of 30.6 (range, 24-44) and 26.8 (range, 24-45) months, respectively ( P = .07). Younger patients demonstrated significantly higher pre- and postoperative Physical Function (mean difference postoperatively, 4.6; 95% confidence interval, 1.5-7.8; P = .03). There were no differences in radiographic parameters postoperatively. There were 8 (36.4%) reoperations (all minor) in the younger group, and 21 (38.9%) reoperations (6 major, 15 minor) in the older group ( P = .84). Conclusion: Our data suggest that age may play a role in clinical outcomes, procedures indicated, and subsequent corrective reoperations. Younger patients maintained greater physical function with comparable radiographic correction, with less frequent indication for tendon transfers, arthrodesis, and additional corrective surgeries. Level of Evidence: Level III, retrospective comparative study.

The United States experienced local transmission of West Nile Virus (WNV) for the first time in 1999, and Zika Virus (ZIKV) in 2016. These introductions captured the public’s attention in varying degrees. The research presented here analyzes the disproportional perception of ZIKV risk compared to WNV transmission risk, by the public and vector control personnel. The risk perception of vector control was measured through purposive sampled interviews (24 interviews in 13 states; May 2020–June 2021), while the public’s perception was estimated from news publications (January 2000–December 2020), and Google searches (January 2004–December 2020). Over time, we observed a decrease in the frequency of press reporting and Google searches of both viruses with decreasing annual peaks in the summer. The highest peak of ZIKV news, and searches, surpassed that of WNV. We observed clear differences in the contents of the headlines for both viruses. We propose that the main reason in risk perception differences between the viruses were psychological. Zika infections (mosquito-borne and sexually transmitted) can result in devastating symptoms in fetuses and newborns, observations that frequently appeared in ZIKV-related headlines. Our results highlight the likely influence the news media has on risk perception and the need for public health agencies to play active roles in the conversation, helping disseminate timely and accurate information. Understanding the factors that shape risk perceptions of vector-borne diseases will hopefully lead to better use of resources by providing better guidance.

The determinants of immunological protection against Mycobacterium tuberculosis (M.tb) infection in humans are not known. Mycobacterial growth inhibition assays have potential utility as in vitro surrogates of in vivo immunological control of M.tb. We evaluated a whole blood growth inhibition assay in a setting with high burden of TB and aimed to identify immune responses that correlate with control of mycobacterial growth. We hypothesized that individuals with underlying M.tb infection will exhibit greater M.tb growth inhibition than uninfected individuals and that children aged 4 to 12 years, an age during which TB incidence is curiously low, will also exhibit greater M.tb growth inhibition than adolescents or adults. Neither M.tb infection status, age of the study participants, nor M.tb strain was associated with differential control of mycobacterial growth. Abundance and function of innate or T cell responses were also not associated with mycobacterial growth. Our data suggest that this assay does not provide a useful measure of age-associated differential host control of M.tb infection in a high TB burden setting. We propose that universally high levels of mycobacterial sensitization (through environmental non-tuberculous mycobacteria and/or universal BCG vaccination) in persons from high TB burden settings may impart broad inhibition of mycobacterial growth, irrespective of M.tb infection status. This sensitization may mask the augmentative effects of mycobacterial sensitization on M.tb growth inhibition that is typical in low burden settings.