Tape-Reinforced Graft Suturing and Retensioning of Adjustable-Loop Cortical Buttons Improve Quadriceps Tendon Autograft Biomechanics in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study.

PURPOSE: To investigate the biomechanical effects of tape-reinforced graft suturing and graft retensioning for all-soft tissue quadriceps tendon (ASTQT) anterior cruciate ligament reconstruction (ACLR) in a full-construct human cadaveric model. METHODS: Harvested cadaveric ASTQT grafts were assigned to either (1) double-suspensory adjustable-loop cortical button device (ALD) fixation in which both graft ends were fixed with a suspensory fixation device with (n = 5) or without (n = 5) tape-reinforced suturing or (2) single-suspensory distal tendon fixation in which only the patellar end was fixed with an ALD (n = 5) or fixed-loop cortical button device (FLD) (n = 5). All specimens were prepared using a No. 2 whipstitch technique, and tape-reinforced specimens had an integrated braided tape implant. Graft preparation time was recorded for double-suspensory constructs. Samples were tested on an electromechanical testing machine using a previously published protocol simulating rehabilitative kinematics and loading. RESULTS: Tape-reinforced graft suturing resulted in greater graft load retention after cycling (11.9% difference, P = .021), less total elongation (mean [95% confidence interval (CI)], 5.57 mm [3.50-7.65 mm] vs 32.14 mm [25.38-38.90 mm]; P < .001), greater ultimate failure stiffness (mean [95% CI], 171.9 N/mm [158.8-185.0 N/mm] vs 119.4 N/mm [108.7-130.0 N/mm]; P < .001), and less graft preparation time (36.4% difference, P < .001) when compared with unreinforced specimens. Retensioned ALD constructs had less cyclic elongation compared with FLD constructs (mean total elongation [95% CI], 7.04 mm [5.47-8.61 mm] vs 12.96 mm [8.67-17.26 mm]; P = .004). CONCLUSIONS: Tape-reinforced graft suturing improves time-zero ASTQT ACLR construct biomechanics in a cadaveric model with 83% less total elongation, 44% greater stiffness, and reduced preparation time compared with a whipstitched graft without tape reinforcement. ALD fixation improves construct mechanics when compared with FLD fixation as evidenced by 46% less total elongation. CLINICAL RELEVANCE: Tape-reinforced implants and graft retensioning using ALDs improve time-zero ACLR graft construct biomechanics in a time-zero biomechanical model. Clinical studies will be necessary to determine whether these implants improve clinical outcomes including knee laxity and the incidence of graft rupture.

Biomechanical comparison of canine median sternotomy closure using suture tape and orthopedic wire cerclage.

OBJECTIVE: To compare the mechanical properties of suture tape and orthopedic wire cerclage in an ex vivo canine median sternotomy model. STUDY DESIGN: Ex vivo. ANIMALS: Twelve large-breed canine cadaveric sternums. METHODS: Median sternotomies were performed, leaving the manubrium intact. The specimens were randomly assigned to group W (20-gauge stainless steel orthopedic wire cerclage in a figure-of-eight pattern) or group ST (suture tape in a figure-of-eight pattern). Each specimen was laterally distracted until failure using an electrodynamic materials-testing system. RESULTS: No differences were observed for displacement, yield load, maximum load, implant failure between the groups. The orthopedic wire construct was stiffer than the suture tape construct. CONCLUSION: Suture tape was biomechanically similar to orthopedic wire cerclage for sternotomy closure in dogs, although wire constructs were stiffer. CLINICAL SIGNIFICANCE: Suture tape may represent an alternative to cerclage wire for sternotomy closure in dogs. Additional studies evaluating its clinical use are needed.

Tracking Anti-Staphylococcus aureus Antibodies Produced In Vivo and Ex Vivo during Foot Salvage Therapy for Diabetic Foot Infections Reveals Prognostic Insights and Evidence of Diversified Humoral Immunity.

Management of foot salvage therapy (FST) for diabetic foot infections (DFI) is challenging due to the absence of reliable diagnostics to identify the etiologic agent and prognostics to justify aggressive treatments. As Staphylococcus aureus is the most common pathogen associated with DFI, we aimed to develop a multiplex immunoassay of IgG in serum and medium enriched for newly synthesized anti-S. aureus antibodies (MENSA) generated from cultured peripheral blood mononuclear cells of DFI patients undergoing FST. Wound samples were collected from 26 DFI patients to identify the infecting bacterial species via 16S rRNA sequencing. Blood was obtained over 12 weeks of FST to assess anti-S. aureus IgG levels in sera and MENSA. The results showed that 17 out of 26 infections were polymicrobial and 12 were positive for S. aureus While antibody titers in serum and MENSA displayed similar diagnostic potentials to detect S. aureus infection, MENSA showed a 2-fold-greater signal-to-background ratio. Multivariate analyses revealed increases in predictive power of diagnosing S. aureus infections (area under the receiver operating characteristic curve [AUC] > 0.85) only when combining titers against different classes of antigens, suggesting cross-functional antigenic diversity. Anti-S. aureus IgG levels in MENSA decreased with successful FST and rose with reinfection. In contrast, IgG levels in serum remained unchanged throughout the 12-week FST. Collectively, these results demonstrate the applicability of serum and MENSA for diagnosis of S. aureus DFI with increased power by combining functionally distinct titers. We also found that tracking MENSA has prognostic potential to guide clinical decisions during FST.

Study of the head and neck position in microlaryngoscopy using magnetic resonance imaging.

Several studies have critically analyzed the ideal position for laryngeal exposure during microlaryngoscopy; however, these studies have lacked the ability to evaluate the head and neck position while maintaining a direct view into the airway. Therefore, a newly established two-curve methodology was used to investigate the influence of head and neck position during microlaryngoscopy in MRI images. Fourteen normal adult volunteers were used in this magnetic resonance imaging study. The airway was divided into two curves in the sagittal plane at the center of the airway in three head and neck positions: extension-extension, neutral and flexion-extension position. The airway passage curves, point of inflection and its tangent, the line of laryngoscope, line of hyoid bone and mandible were plotted on each scan. Angles and area formed by these lines were calculated to evaluate the airway morphology changes. The flexion-extension position caused a reduction in the area between the line of laryngoscope and curves, but there was no significant difference between the three positions (p = 0.664). The flexion-extension position also resulted in the lowest angle values for α (angle between the tangent and horizon, p = 0.000), ß (between the line of hyoid and horizon, p = 0.002) and δ (between the line of mandible and horizon, p = 0.004). Our study provides a better understanding of the changes in normal airway morphology during microlaryngoscopy in different positions, reinforcing the concept that flexion-extension position is the optimal position for microlaryngoscopy.

Autologous Fibrin Sealants Have Comparable Graft Fixation to an Allogeneic Sealant in a Biomechanical Cadaveric Model of Chondral Defect Repair.

Purpose: The purpose of this study is to assess the integrity of chondral defect repairs filled with a cartilage allograft and sealed with either allogeneic fibrin sealant or autologous fibrin sealants created with platelet-rich plasma (PRP) or platelet-poor plasma (PPP) in a cadaver model. Methods: Twenty-millimeter medial femoral condyle (MFC) chondral defects were created in five human cadaveric knees. The defects were filled with particulated cartilage allograft hydrated with PRP from human donors until slightly recessed. Sealants were applied until flush with the articular surface using PRP and autologous thrombin serum, PPP and autologous thrombin serum, or commercial allogeneic sealant. The MFC defects were cycled using a multiaxial testing system to simulate continuous passive motion undergone during rehabilitation. After testing, the repairs were assessed for integrity by quantitatively comparing defect exposure and qualitatively assessing sealant delamination. Results: The mean defect exposures were 4.20% ± 5.02% for the PRP group, 4.60% ± 5.18% for the PPP group, and 1.80% ± 2.95% for the allogeneic sealant group. No significant differences were observed between groups (P = .227), and each group had significantly less defect exposure when compared to the critical clinically relevant value assigned to be 30% (P = <.001 for all). No complete sealant delamination was observed, although the allogeneic sealant delaminated with a higher magnitude than did the autologous sealants. Conclusions: The PRP and PPP sealants were comparable to the allogeneic sealant for graft fixation when used in conjunction with an underlying PRP-hydrated particulated cartilage allograft. The autologous sealants had better delamination resistance than the allogeneic sealant. Clinical Relevance: The time-zero model is critical in elucidating the retention properties of fibrin and allogenic sealants after cartilage repair and before healing processes help stabilize the repair.

Effect of variations to a simulated system of straw phonation therapy on aerodynamic parameters using excised canine larynges.

OBJECTIVES/HYPOTHESIS: Resonance tubes are commonly used in voice therapy. These devices modify supraglottal impedance, potentially decreasing the aerodynamic power necessary for phonation. We modeled phonation with resonance tubes in excised larynges and evaluated the effects of varying tube width, tube length, and flow input on phonation threshold pressure (PTP) and phonation threshold flow (PTF). We hypothesized that the increased vocal economy observed in human subjects and several other models would be observed in excised larynges. STUDY DESIGN: Repeated measures excised canine larynx bench experiment with each larynx serving as own control. METHODS: Nine conditions were evaluated, namely control, two tube diameters (17.5 and 6.5mm), three tube lengths (7.8, 15.0, and 30.0cm), and three levels of flow input (80, 114, and 200mL/s). Aerodynamic data were collected for 11 excised canine larynges attached to an artificial vocal tract, and results from each experimental configuration were compared with control. RESULTS: A significant decrease in average PTP occurred compared with control for the 114- and 200-mL/s flow inputs, 30-cm extension, and 17.5- and 6.5-mm constrictions. Average PTF decreased compared with control for every configuration, although statistically significant changes were only observed for 200-mL/s flow and 6.5-mm constriction. CONCLUSIONS: Knowledge regarding the effect of vocal tract alterations could be clinically useful in determining the optimal "straw" configuration for voice therapy. Further exploration of the relationships among width, length, and flow input could provide theoretical support for the development of new therapies and resonance tube devices.

Expression of hypoxia inducible factor-1α and vascular endothelia growth factor in vocal polyps.

OBJECTIVES/HYPOTHESIS: Long-term vocal overuse or sudden vocal-fold microvascular disruption may lead to the formation of a hypoxic zone of injury and the subsequent release of a cascade of cytokines in the vocal fold. To test this hypothesis, we investigated the expression and the role of hypoxia inducible factor-1α (HIF-1α) and vascular endothelia growth factor (VEGF) in the formation of vocal polyps. METHODS: Expression patterns of HIF-1α and VEGF in surgical specimens of vocal polyps from 36 patients were analyzed using the immunohistochemistry and Western blot method. Normal vocal-fold mucosa from 26 patients who underwent total laryngectomy were collected and used as the control group. RESULTS: The expression of HIF-1α and VEGF were detected both in the vocal polyps group and the control group, while the expression of HIF-1α and VEGF levels were significantly higher when compared to normal vocal-fold mucosa (P < .05). CONCLUSION: The increased expression of HIF-1α in vocal polyps indicates that vocal fold overvibration induced hypoxia may play an important role in the pathogenetic mechanism of vocal polyps.

Nonlinear source-filter coupling due to the addition of a simplified vocal tract model for excised larynx experiments.

OBJECTIVES: Traditional excised larynx dissection and setup calls for the removal of all supraglottal structures, eliminating any source-filter interactions that measurably affect the acoustic properties of phonation. We introduce a simplified vocal tract model that can be used in the excised larynx experiments and tested the nonlinear source-filter interactions that are present with the addition of highly coupled, supraglottal structures. METHODS: Aerodynamic and acoustic data were measured at phonation threshold pressure (PTP) and +25% PTP in 10 excised canine larynges using a modified dissection technique. PTP and phonation threshold flow (PTF) were defined as the pressure and flow at the phonation onset; phonation threshold power (PTW) is the product of these values. Data were recorded for four experimental conditions: PTP without vocal tract; +25% PTP without vocal tract; PTP with vocal tract; and +25% PTP with vocal tract. Differences in PTP, PTF, and PTW were evaluated. For trials conducted at +25% PTP, differences in airflow were evaluated. RESULTS: PTP (P = 0.009) and PTW (P = 0.002) were significantly reduced with the addition of the novel vocal tract. A reduction in PTF was also present with the vocal tract (P = 0.021), but airflow was not significantly reduced in +25% PTP trials (P = 0.196). CONCLUSION: The proposed vocal tract can be used with complete larynges when conducting excised larynx experiments. The effects of nonlinear source-filter interaction were observed during trials with the vocal tract, as evidenced by changes in threshold aerodynamic parameters.

Use of the rabbit larynx in an excised larynx setup.

OBJECTIVE: To modify the excised larynx bench apparatus to accommodate experiments with rabbit larynges. STUDY DESIGN: Methodological study using ex vivo rabbit larynges. METHODS: Rabbit larynges (n=5) were dissected and mounted on a custom-made phonatory apparatus. The arytenoids were adducted by rods, and humidified air was passed through the larynx to elicit vocal fold vibration. Acoustic, aerodynamic, electroglottographic (EGG), and videokymographic data were collected for each larynx. The same data were collected for five canine larynges for the purpose of comparison, and coefficients of variation were calculated for each parameter in both models. RESULTS: Reliable phonation was achieved in each larynx. Acoustic fundamental frequency (F(0)), percent jitter, percent shimmer, signal-to-noise ratio, pressure and flow at phonation onset and offset; and F(0), closed quotient, speed quotient, jitter, shimmer, and contact quotient, as recorded by EGG; and mucosal wave amplitude and phase difference are reported for rabbit larynges. Coefficients of variation for each parameter are similar in magnitude between the two models. CONCLUSION: We developed a method for recording reliable acoustic, aerodynamic, videokymographic, and EGG data from rabbit larynges. When data obtained from leporine larynges were compared with data from canine larynges, the intralarynx variability of rabbit larynges was found to be similar to that of canine larynges.