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Category: Trauma; Basic Sciences/Biologics Introduction/Purpose: A variable pitch locking screw is intended to provide interfragmentary compression combined with fixed angle stability of locking plate constructs. The objective of this study was to compare variable pitch locking screws with standard locking screws in bicortical fixation scenarios in cadaver bone, by assessing: (1) interfragmentary compression and plate-bone compression; and (2) construct biomechanical stability. Methods: Nine matched pairs of fresh-frozen cadaveric specimens were used to compare variable pitch locking screws and standard locking screws. First, interfragmentary compression and plate-bone compression associated with insertion of single bicortical screws at increasing levels of torque were measured in distal tibiae having a simulated longitudinal fracture. Second, fibulae were osteotomized to create a stable fracture pattern, fixed with five-screw plated constructs, and tested in either cyclic axial and torsional loading or four-point bending. Results: Interfragmentary and plate-bone compression forces were significantly higher with variable pitch locking screws compared to standard locking screws (p =0.002 & p=0.028, respectively). The amount of compression was variable across specimens. In cyclic loading of fibula constructs, no significant differences were detected in construct axial displacement or angular displacement. In four-point bending, no differences were detected in maximum force or bending stiffness. Conclusion: Variable pitch locking screws can produce high interfragmentary compression between cortices, along with moderate plate-bone compression. In a stable bicortical fixation scenario under external loading, construct stability was similar to normal locking screws.

Objective: To assess if a surgical boot camp improves laparoscopic skill among reproduction endocrinology and infertility (REI) fellows and increases fellow desire to incorporate surgical skills into practice and to examine whether fellowship in vitro fertilization (IVF) volume correlates with surgical efficiency. Design: Prospective evaluation. Setting: Simulation Center. Patient(s): Forty REI fellows. Intervention(s): Fellows were timed before and after training in laparoscopic suturing and knot tying and while using virtual simulators. Fellows were surveyed before boot camp on prior experience with IVF and reproductive surgery, and immediately and 1 month after boot camp on their desire to incorporate surgical skills into practice. Main Outcome Measure(s): Efficiency of laparoscopic suturing and knot tying before and after boot camp; likelihood and persistence of incorporating surgical skills into practice immediately and 1 month after boot camp; and correlation between fellowship IVF volume and fellow surgical efficiency. Result(s): Fellows experienced significant improvement in laparoscopic suturing (44 sec), intracorporeal knot tying (82 sec), and extracorporeal knot tying (71 sec). Fellows reported being more likely to incorporate operative hysteroscopy (89%), operative laparoscopy (87%), and laparoscopic suturing (84%) into practice immediately following boot camp with no difference 1 month later. Fifty-four percent of fellows reported being more likely to perform robotic surgery after the boot camp, increasing to 70% 1 month later. There were weak correlations between IVF case volume and efficiency in laparoscopic suturing or hysteroscopic polypectomy (Spearman correlation coefficients, -0.14 and -0.03). Conclusion(s): An intensive surgical boot camp enhances surgical skill among REI fellows.

During embryonic development, tendons transform into a hypocellular tissue with robust tensile load-bearing capabilities. Previous work suggests that this mechanical transformation is due to increases in collagen fibril length and is dependent on mechanical stimulation via muscle activity. However, the relationship between changes in the microscale tissue structure and changes in macroscale tendon mechanics is still unclear. Additionally, the specific effect of mechanical stimulation on the multiscale structure-function relationships of developing tendons is also unknown. Therefore, the objective of this study was to measure the changes in tendon mechanics and structure at multiple length scales during embryonic development with and without skeletal muscle paralysis. Tensile testing of tendons from chick embryos was performed to determine the macroscale tensile modulus as well as the magnitude of the fibril strains and interfibrillar sliding with applied tissue strain. Embryos were also treated with either decamethonium bromide or pancuronium bromide to produce rigid or flaccid paralysis. Histology was performed to assess changes in tendon size, spacing between tendon subunits, and collagen fiber diameter. We found that the increase in the macroscale modulus observed with development is accompanied by an increase in the fibril:tissue strain ratio, which is consistent with an increase in collagen fibril length. Additionally, we found that flaccid paralysis reduced the macroscale tendon modulus and the fibril:tissue strain ratio, whereas less pronounced effects that were not statistically significant were observed with rigid paralysis. Finally, skeletal paralysis also reduced the size of collagen fibril bundles (i.e., fibers). Together, these data suggest that more of the applied tissue strain is transmitted to the collagen fibrils at later embryonic ages, which leads to an increase in the tendon macroscale tensile mechanics. Furthermore, our data suggest that mechanical stimulation during development is necessary to induce structural and mechanical changes at multiple physical length scales. This information provides valuable insight into the multiscale structure-function relationships of developing tendons and the importance of mechanical stimulation in producing a robust tensile load-bearing soft tissue.

Category: Trauma; Basic Sciences/Biologics; Midfoot/Forefoot; Sports Introduction/Purpose: Lisfranc ligamentous injuries are complex. Controversy exists regarding their treatment and preferred method of fixation. Fixation methods employing a FiberTape device and interference screw fixation have been described as an alternative to traditional screw fixation. The purpose of this biomechanical study was to evaluate two methods of fixation utilizing interference screw fixation with FiberTape augmentation in a cadaveric model. Methods: 9 paired cadaveric feet (mid tibia/fibula) were separated into two groups based on fixation method: FiberTape alone and FiberTape with supplementary limb into the middle cuneiform via anchor. At three joints of the midfoot (second metatarsal - medial cuneiform, intermediate cuneiform - medial cuneiform, second metatarsal - intermediate cuneiform), the diastasis and relative angular displacement between bones in the coronal plane were measured for static and cyclic loading. Measurements were obtained for the native (pre-injured), injured, and post-fixation in static loading. Fixed specimens then underwent stepwise increases in cyclic loading performed at 1 Hz and 100 cycles, at 100 N intervals from 500 to 1800 N ground reaction force. The Achilles tendon was also loaded to simulate postoperative weightbearing. Failure of fixation was defined as diastasis at the second metatarsal - medial cuneiform joint greater than 2 millimeters. Results: FiberTape specimens demonstrated diastasis failures of 3 of 9 (33%) specimens at cyclic loads of 1000 N. Conversely, FiberTape with supplementary limb specimens all survived past this loading magnitude, with 1 failing at supraphysiologic loads (>1200 N). The difference in diastasis at the second metatarsal-medial cuneiform joint was statistically significant between the two groups at forces of 1600N (p = 0.019) and 1800N (p = 0.029). There were no significant differences between the other joint diastases and relative angular displacements. Conclusion: The use of FiberTape for fixation of ligamentous Lisfranc injuries appears to provide a biomechanically viable alternative for withstanding early post-operative protected weightbearing. Furthermore, the use of a supplementary limb in addition to the FiberTape fixation method appears to enhance its biomechanical efficacy under cyclic loading especially at higher loads.

INTRODUCTION: Corneal transplantation is a surgical procedure requiring consistent long-term follow-up to maximize the chance of graft survival. The purpose of this study was to explore patient characteristics and reasons for being lost to follow-up (LTFU). METHODS: a retrospective review of clinical records from January 2012 to October 2014 was conducted of patients who received corneal transplantation at Tenwek Hospital. At the time of chart review, all patients who provided a mobile phone number were contacted to answer a phone questionnaire. Logistic regression was used to assess the association of each patient characteristic, separately, with the outcome of LTFU. RESULTS: of the 118 patients that met inclusion criteria, 40 (33.9%) were considered LTFU by failing to follow up at Tenwek Hospital to at least one year postoperatively. The odds of LTFU for patients age 60 and older were 3.78 times that of those who were 18-59 (95% CI: 1.21-11.80]; p-value=0.02). The odds of LTFU for patients with a preoperative diagnosis of pseudophakic bullous keratopathy were 3.83 times that of those with a preoperative diagnosis of keratoconus (95% CI: [1.13-12.94]; p-value=0.03). Education level, employment status, distance from the hospital and possession of a mobile contact number appeared marginally associated with follow-up status, though not statistically significant at the 0.05 significance level. Financial barriers was the most commonly cited reason for LTFU (42.4%, n=14). CONCLUSION: certain reasons and patient characteristics may be associated with follow-up adherence. Identifying these factors may help providers identify patients who are at a higher risk of LTFU and influence providers in medical decision-making and system-based interventions when offering corneal transplantation.

ABSTRACT Prolonged reduction in weightbearing causes bone loss. Disuse of bone is associated with recovery from common musculoskeletal injury and trauma, bed rest resulting from various medical conditions, and spaceflight. The hindlimb‐suspension rodent model is popular for simulating unloading and disuse. We hypothesized that controlled mechanical loading of the tibia would protect against bone loss occurring from concurrent disuse. Additionally, we hypothesized that areas of high mechanical peak strains (midshaft) would provide more protection than areas of lower strain (distal shaft). Adult C57BL6/J mice were suspended for 3 weeks, with one limb subjected to tibial compression four times per week. μCT imaging was completed at days 0, 11, and 21, in addition to serum analysis. Significant bone loss caused by hindlimb suspension was detected in trabecular bone by day 11 and worsened by day 21 (p

Abstract Objective Sepsis is a condition associated with a dysregulated inflammatory response to infection with significant morbidity. Recent advances have elucidated the vital role that the short chain fatty acid glycoprotein receptor 43 (FFA2/GPR43) plays in inflammatory and immunomodulatory pathways. We hypothesized that elevated whole blood GPR43 RNA expression would be associated with increased 30-day survival in patients admitted with sepsis. Patients (n = 93) admitted to the intensive care unit with the diagnosis of sepsis underwent quantitative real time PCR within 48 h of intensive care unit admission. Clinical and demographical parameters were retrospectively extracted from the chart and compared to quantitative measurements of GPR43 RNA expression. Results Utilizing logistic regression, we found that the odds of mortality decreased for every one-unit increase in GPR43 RNA expression for patients that survived to 30 days [OR = 0.71; 95% CI (0.50, 0.99) p = 0.049]. Using linear regression, we determined that the increase in whole blood GPR43 expression was not associated with whole blood white cell count [r = 0.04; 95% CI (−0.16, 0.24); p = 0.70] or body mass index [r = − 0.07; 95% CI (− 0.23, 0.18); p = 0.81]. We conclude that the GPR43 receptor plays an integral role in survival during and after sepsis.

Category: Hindfoot Introduction/Purpose: Posterior Tibial Tendon Dysfunction (PTTD) is common disorder that can lead to changes in function during the gait cycle due to decreased arch, increased hindfoot valgus, and forefoot abduction. These kinematic changes can have a structural impact on the joints throughout the foot. While previous studies have evaluated anatomical three-dimensional (3D) position of the subtalar joint, the purpose of this study was to perform morphological analysis of the anterior, middle and posterior facets in patients with stage II posterior tibial tendon dysfunction compared to normal controls. Methods: Clinical computed tomography images from 10 matched feet (i.e., 10 normal and 10 stage II PTTD) were obtained and used for 3D reconstruction in Mimics software (Materialise). From the3D reconstructions, morphometric evaluations of the subtalar joint were completed including 3D anatomic point placement and measurements of the length and width of the anterior, middle and posterior facets (Fig. 1) by 3 independent evaluators. Evaluators were blinded to experimental groups and to one another’s measurements. A linear mixed-effects model was used to assess the differences between control and PTTD subtalar joints with respect to morphometric measurements (mm). The concordance correlation coefficient (CCC) was used to assess the agreement between the 3 evaluators with respect to their recorded morphometric measurements per location (e.g., anterior, middle, posterior). Results: Although the mean distance of the length and width of the middle facet trended higher in the stage II PTTD compared to controls, this difference was not statistically significant (Table 1). Similarly, there was no difference detected between control and PTTD with respect to morphometric measurements in the anterior and posterior facets (Table 1). The agreement among the 3 evaluators with respect to morphometric measurements was the strongest in the length and width of the middle facets. Conclusion: Stage II posterior tibial tendon dysfunction has been shown to cause increase subtalar joint kinematics, joint contact pressure. Based on the results, there is a positive correlation involving morphologic changes of subtalar joint with the middle facet measurements being larger in the PTTD group. Further studies are needed with weight bearing CT scans in correlation with advance stages of posterior tibial tendon dysfunction.

Category: Hindfoot Introduction/Purpose: The pathophysiology of adult-acquired flatfoot deformity (AAFD) is not fully explained by degeneration of the posterior tibial tendon alone. While a shortened or dysplastic lateral column has been implicated in flatfoot deformity in pediatric population, there is no study that has quantified the degree of shortening or dysplasia in adults with a stage IIb flatfoot deformity, or if any exists at all. The purpose of this study was to use reconstructive 3D modeling from computed tomography (CT) scans of the calcaneus in order to perform three-dimensional morphometric measurements of the lateral column in patients with stage IIb posterior tibial tendon dysfunction (PTTD) compared to controls in an effort to better understand the morphology of patients with AAFD. Methods: After IRB approval, an institutional radiology database was queried for patients with PTTD who had CT performed between January 2011 and June 2016. Controls were patients receiving CT scan for an intraarticular distal tibia fracture without preexisting foot or calcaneal pathology. Clinical office notes, physical examination, and weight-bearing radiographs were used to identify patients that met clinical criteria for stage IIb PTTD. A 1:1 match was performed using age, laterality, gender, and BMI. Morphometric measurements of the calcanei were performed involving the length of the calcaneal axis (LCA), height of the anterior process (HAP), and length of the anterior process (LAP) (Figure 1). Linear mixed-effects models were used to assess the differences between control and PTTD patients with respect to LAP, HAP, and LCA measurements, with also considering measurements from 3 independent observers. We considered a difference of ± 4 mm as our threshold of clinical significance. Results: Of the 3586 CT within our institutional database, a total of 14 patients were available for reconstruction and analysis. There were no statistical differences detected between patient characteristics or demographics between these groups. On average, the long axis of the calcaneus (LCA) was 3.1 mm shorter (95% confidence interval: 0.43-5.76 mm) in patients with stage IIb PTTD compared to controls (p

We prospectively correlated the 24-hour ambulatory blood pressure measurements (ABPM) to conventional sphygmomanometer blood pressure measurements (CSM) in women at risk for gestational hypertensive disorders (GHTNDs) and identified predictive factors from ABPM for GHTND. We analyzed 73 women with ≥1 risk factor for developing a GHTND. Using both the CSM and ABPM, the systolic blood pressure, diastolic blood pressure, mean arterial pressure (MAP), and heart rate (HR) were measured for 24 hours during three periods (14 to 24 weeks; 24 to 32 weeks; and 33 weeks to delivery). Correlation between the CSM and ABPM lessened as pregnancy progressed. Seventeen (25%) of women developed a GHTND. MAP variability increased in the GHTND group versus those without a GHTND. The odds of developing a GHTND increased 1.5 times for every 1 beat per minute increase in the ABPM 24-hour HR at visit 1 and reversed by visit 3. In women at risk for a GHTND, CSM and ABPM correlate less well as pregnancy advances. HR changes in at-risk women may be a marker for the development of a GHTND and may reflect increased sympathetic activity and/or decreased baroreceptor sensitivity. [ABSTRACT FROM AUTHOR]