A scoping review of therapist behaviors in guided digital mental health interventions.

Guided digital mental health interventions are more effective than unguided interventions. While research often emphasizes the frequency and intensity of guidance, less attention has been paid to the behaviors enacted by the therapists supporting clients using these interventions. A scoping review of the literature was conducted to systematically examine the evidence on therapist behaviors (i.e., the actions and feedback provided by supporters to patients). Applying broad eligibility criteria, a systematic search was conducted in PubMed, PsycInfo, the Cochrane Library, and Embase from their inception to January 1st 2024. Sixteen studies met inclusion criteria and were included in the review. Following data extraction, a descriptive analysis and synthesis of the results was performed. Most studies (n = 12; 75 %) focused on therapist behaviors in the context of internet-delivered Cognitive Behavioral Therapy for anxiety and depression. While earlier studies primarily focused on identifying therapist behaviors, later studies shifted towards examining the associations between therapist behaviors and different outcomes, as well as deriving research and clinical applications for improving guided internet-delivered treatments. Identified gaps and recommendations for clinical practice, research, training, and treatment development are discussed.

IntEgrating Smoking Cessation treAtment into usual online Psychological care for people with common mEntal illness: Protocol for an online randomised feasibility and pilot study (ESCAPE digital).

BACKGROUND: In the UK, smoking prevalence in people with depression (34%) and anxiety (29%) is more than double that of the general population (13%). People who stop smoking improve their mental health with comparable effect sizes found for antidepressants. In England, online psychological therapy is a standard treatment for depression and anxiety. Online therapy is an acceptable setting for smoking cessation support; however, integrated smoking and mental health support is not available. This novel study aims to assess the acceptability and feasibility of an online smoking cessation intervention, and trial procedures, offered alongside online mental health treatment as it offers increased reach to people with common mental health difficulties who smoke. METHODS: A two-armed; Intervention (Integrated SilverCloud smoking cessation support) and control group (SilverCloud usual care), pragmatic, randomised controlled feasibility trial. We aim to recruit 500 adult smokers eligible for online mental health treatment. Follow-up will be conducted at 3-months and 6-months. We will assess the acceptability and feasibility of the trial procedures (i.e., recruitment, data completeness, self-reported acceptability and satisfaction) and the intervention (i.e., self-reported quit attempt, engagement with the smoking cessation and mental health programs, smoking cessation medicine and e-cigarette use, self-reported acceptability and satisfaction) and pilot clinical outcomes (i.e., biologically validated smoking abstinence, anxiety, depression, quality of health). CONCLUSION: If the Trial is successful, a randomised controlled effectiveness trial will follow to examine whether integrated smoking cessation and mental health treatment increases smoking abstinence and improves depression and anxiety compared to usual care. TRIAL REGISTRATION: ISRCTN10612149 (https://doi.org/10.1186/ISRCTN10612149), 02/02/2023.

Development and initial evaluation of a treatment integrity measure for low-intensity group psychoeducational interventions.

BACKGROUND: Despite the importance of assessing the quality with which low-intensity (LI) group psychoeducational interventions are delivered, no measure of treatment integrity (TI) has been developed. AIMS: To develop a psychometrically robust TI measure for LI psychoeducational group interventions. METHOD: This study had two phases. Firstly, the group psychoeducation treatment integrity measure-expert rater (GPTIM-ER) and a detailed scoring manual were developed. This was piloted by n=5 expert raters rating the same LI group session; n=6 expert raters then assessed content validity. Secondly, 10 group psychoeducational sessions drawn from routine practice were then rated by n=8 expert raters using the GPTIM-ER; n=9 patients also rated the quality of the group sessions using a sister version (i.e. GPTIM-P) and clinical and service outcome data were drawn from the LI groups assessed. RESULTS: The GPTIM-ER had excellent internal reliability, good test-retest reliability, but poor inter-rater reliability. The GPTIM-ER had excellent content validity, construct validity, formed a single factor scale and had reasonable predictive validity. CONCLUSIONS: The GPTIM-ER has promising, but not complete, psychometric properties. The low inter-rater reliability scores between expert raters are the main ongoing concern and so further development and testing is required in future well-constructed studies.

Lifting, Loading, and Buckling in Conical Shells.

Liquid crystal elastomer films that morph into cones are strikingly capable lifters. Thus motivated, we combine theory, numerics, and experiments to reexamine the load-bearing capacity of conical shells. We show that a cone squashed between frictionless surfaces buckles at a smaller load, even in scaling, than the classical Seide-Koiter result. Such buckling begins in a region of greatly amplified azimuthal compression generated in an outer boundary layer with oscillatory bend. Experimentally and numerically, buckling then grows subcritically over the full cone. We derive a new thin-limit formula for the critical load, ∝t^{5/2}, and validate it numerically. We also investigate deep postbuckling, finding further instabilities producing intricate states with multiple Pogorelov-type curved ridges arranged in concentric circles or Archimedean spirals. Finally, we investigate the forces exerted by such states, which limit lifting performance in active cones.

Implementing internet-delivered cognitive behavioral therapy in healthcare services: a qualitative exploration of stakeholder experience.

Background: This study consisted of a qualitative exploration of stakeholder experience regarding the implementation of internet-delivered cognitive behavioral therapy (iCBT) as part of routine service provision within the UK's Improving Access to Psychological Therapies program. Methods: Stakeholder groups included service providers (n = 6), commercial iCBT representatives (n = 6) and patients who received a course of iCBT as part of treatment at the service (n = 7). Participants took part in a semi-structured interview over the telephone, and subsequent data were qualitatively analyzed using the descriptive-interpretive approach. Results: Service providers highlighted the importance of effective leadership and management, training initiatives, the provision of feedback to commercial iCBT representatives and creating work structures around iCBT to facilitate iCBT supporting staff in their use of it. Commercial iCBT representatives similarly reported the importance of training clinicians in iCBT use, identifying the appropriate individuals at all levels of the service to drive iCBT implementation, and the importance of being responsive to any problems or needs that arise from the service. Patients reported an overall positive experience of receiving iCBT but highlighted a need for more information from their supporter and the intervention to better structure their usage. Contextual factors, in terms of barriers and facilitators, were also highlighted by service provider and commercial participants; citing negative clinician attitudes and technological issues/bugs as barriers to implementation, and the exposure to iCBT created by COVID-19 and perseverance in using iCBT over time as facilitators. Discussion: The findings contribute to a growing field of literature that seeks to understand the experience of relevant stakeholders who are involved with and contribute to iCBT implementation, including commercial iCBT representatives who, to our knowledge, have not been accounted for as part of published research to date.

Biomechanical evaluation of three adjunctive methods of orthopedic tension band-wire fixation to augment simulated patella tendon repairs in dogs.

OBJECTIVE: To evaluate the effects of three adjunctive methods of tension band wire fixation (TBWF) on the biomechanical properties, gap formation, and failure mode in simulated canine patella tendon rupture (RPT). STUDY DESIGN: Randomized, ex vivo. SAMPLE POPULATION: Paired hindlimbs from 32 dog cadavers. METHODS: Patellar tendons (PTs) and associated bone-muscle-tendon units were harvested. Each PT was transected then sutured using a core locking loop and simple continuous epitendinous pattern. Each hindlimb was randomly assigned to one of three groups (n = 18 hindlimbs/group) using 18 gauge 316 L wire, anchored to the tibial crest distally, to perform transpatellar, suprapatellar, or combined tension band-wire (TBW) augmentation. Ten hindlimbs were utilized as control specimens. Yield, peak, and failure loads, stiffness, loads to 1 and 3 mm gap formation, and failure mode were evaluated. RESULTS: Combined transpatellar and suprapatellar TBW augmentation was superior to transpatellar or suprapatellar groups alone. Yield (p = .0008), peak (p = .004), and failure loads (p = .005) were greater for the combined group than for the transpatellar (p = .048) and suprapatellar groups (p = .01) respectively. There was no difference regarding the occurrence of 1 or 3 mm gap formation (1 mm, p = .05; 3 mm, p = .06); however, loads required to cause gap formation were greater in the combined group (p = .036). Mode of failure differed between techniques used for PT augmentation (p < .001). CONCLUSION: Combined transpatellar and suprapatellar adjunctive TBW augmentation for simulated PT repairs was biomechanically superior to either transpatellar or suprapatellar TBWF alone. CLINICAL SIGNIFICANCE: Combined suprapatellar and transpatellar TBWF may offer a viable surgical option for increased repair-site strength and greater loads to gap formation. Further studies investigating alternative techniques and materials for RPT repair augmentation are warranted.

Trajectories of Symptoms in Digital Interventions for Depression and Anxiety Using Routine Outcome Monitoring Data: Secondary Analysis Study.

BACKGROUND: Research suggests there is heterogeneity in treatment response for internet-delivered cognitive behavioral therapy (iCBT) users, but few studies have investigated the trajectory of individual symptom change across iCBT treatment. Large patient data sets using routine outcome measures allows the investigation of treatment effects over time as well as the relationship between outcomes and platform use. Understanding trajectories of symptom change, as well as associated characteristics, may prove important for tailoring interventions or identifying patients who may not benefit from the intervention. OBJECTIVE: We aimed to identify latent trajectories of symptom change during the iCBT treatment course for depression and anxiety and to investigate the patients' characteristics and platform use for each of these classes. METHODS: This is a secondary analysis of data from a randomized controlled trial designed to examine the effectiveness of guided iCBT for anxiety and depression in the UK Improving Access to Psychological Therapies (IAPT) program. This study included patients from the intervention group (N=256) and followed a longitudinal retrospective design. As part of the IAPT's routine outcome monitoring system, patients were prompted to complete the Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) after each supporter review during the treatment period. Latent class growth analysis was used to identify the underlying trajectories of symptom change across the treatment period for both depression and anxiety. Differences in patient characteristics were then evaluated between these trajectory classes, and the presence of a time-varying relationship between platform use and trajectory classes was investigated. RESULTS: Five-class models were identified as optimal for both PHQ-9 and GAD-7. Around two-thirds (PHQ-9: 155/221, 70.1%; GAD-7: 156/221, 70.6%) of the sample formed various trajectories of improvement classes that differed in baseline score, the pace of symptom change, and final clinical outcome score. The remaining patients were in 2 smaller groups: one that saw minimal to no gains and another with consistently high scores across the treatment journey. Baseline severity, medication status, and program assigned were significantly associated (P<.001) with different trajectories. Although we did not find a time-varying relationship between use and trajectory classes, we found an overall effect of time on platform use, suggesting that all participants used the intervention significantly more in the first 4 weeks (P<.001). CONCLUSIONS: Most patients benefit from treatment, and the various patterns of improvement have implications for how the iCBT intervention is delivered. Identifying predictors of nonresponse or early response might inform the level of support and monitoring required for different types of patients. Further work is necessary to explore the differences between these trajectories to understand what works best for whom and to identify early on those patients who are less likely to benefit from treatment.

Evaluation of Radiosensitization and Cytokine Modulation by Differentially PEGylated Gold Nanoparticles in Glioblastoma Cells.

Glioblastoma (GBM) is known as the most aggressive type of malignant brain tumour, with an extremely poor prognosis of approximately 12 months following standard-of-care treatment with surgical resection, radiotherapy (RT), and temozolomide treatment. Novel RT-drug combinations are urgently needed to improve patient outcomes. Gold nanoparticles (GNPs) have demonstrated significant preclinical potential as radiosensitizers due to their unique physicochemical properties and their ability to pass the blood-brain barrier. The modification of GNP surface coatings with poly(ethylene) glycol (PEG) confers several therapeutic advantages including immune avoidance and improved cellular localisation. This study aimed to characterise both the radiosensitizing and immunomodulatory properties of differentially PEGylated GNPs in GBM cells in vitro. Two GBM cell lines were used, U-87 MG and U-251 MG. The radiobiological response was evaluated by clonogenic assay, immunofluorescent staining of 53BP1 foci, and flow cytometry. Changes in the cytokine expression levels were quantified by cytokine arrays. PEGylation improved the radiobiological efficacy, with double-strand break induction being identified as an underlying mechanism. PEGylated GNPs also caused the greatest boost in RT immunogenicity, with radiosensitization correlating with a greater upregulation of inflammatory cytokines. These findings demonstrate the radiosensitizing and immunostimulatory potential of ID11 and ID12 as candidates for RT-drug combination in future GBM preclinical investigations.

Influence of three different closure techniques on leakage pressures and leakage location following partial cystectomies in normal dogs.

BACKGROUND: Transitional cell carcinoma (TCC) is the most common neoplasia affecting the canine urinary bladder. Partial cystectomy, when used adjuctively with medical management, has been shown to meaningfully extend medial survival time. Surgical stapling devices have a wide variety of uses and advantages over traditional closure methods and, to date, investigation into their use in canine partial cystectomies has not been documented. OBJECTIVE: To determine the influence of three closure techniques on ex vivo leakage pressures and leakage location following canine partial cystectomy. METHODS: Specimens were assigned to one of three closure techniques: simple continuous appositional closure with 3-0 suture, closure with a 60 mm gastrointestinal stapler with a 3.5 mm cartridge, and placement of a Cushing suture to augment the stapled closure, with each group containing 12 specimens. Mean initial leakage pressure (ILP), maximum leakage pressure (MLP), and leakage location at the time that ILP was recorded were compared between groups. RESULTS: Oversewn stapled constructs leaked at significantly higher ILP (28.5 mmHg) than those in the sutured (17 mmHg) or stapled (22.8 mmHg) group, respectively. MLP was greater in the oversewn stapled construct group compared to other groups. Leakage was detected in 97% partial cystectomies, with leakage occurring from the needle holes in 100% of the sutured closure group, from the staple holes in 100% of the stapled only group, and from the incisional line in 83% and from bladder wall rupture in 8% of the augmented staple closure group. All closure methods withstood normal physiologic cystic pressures. CONCLUSIONS: Placement of a Cushing suture to augment stapled closures improved the ability of partial cystectomies to sustain higher intravesicular pressures compared with sutured or stapled bladder closures alone. Further in vivo studies are required to determine the clinical significance of these findings and the role of stapling equipment for partial cystectomy, as well as the clinical significance of suture penetration through the urinary bladder mucosa during closure.

Discontinuous Metric Programming in Liquid Crystalline Elastomers.

Liquid crystalline elastomers (LCEs) are shape-changing materials that exhibit large deformations in response to applied stimuli. Local control of the orientation of LCEs spatially directs the deformation of these materials to realize a spontaneous shape change in response to stimuli. Prior approaches to shape programming in LCEs utilize patterning techniques that involve the detailed inscription of spatially varying nematic fields to produce sheets. These patterned sheets deform into elaborate geometries with complex Gaussian curvatures. Here, we present an alternative approach to realize shape-morphing in LCEs where spatial patterning of the crosslink density locally regulates the material deformation magnitude on either side of a prescribed interface curve. We also present a simple mathematical model describing the behavior of these materials. Further experiments coupled with the mathematical model demonstrate the control of the sign of Gaussian curvature, which is used in combination with heat transfer effects to design LCEs that self-clean as a result of temperature-dependent actuation properties.

Influence of Kirschner-Wire Insertion Angle on Construct Biomechanics following Tibial Tuberosity Osteotomy Fixation in Dogs.

OBJECTIVES: The aim of this study was to evaluate the effect of Kirschner wire insertion angle on the biomechanical characteristics following tibial tuberosity osteotomy fixation in dogs. STUDY DESIGN: Twelve pairs of cadaveric tibia were harvested and randomly assigned to two treatment groups. Kirschner wires were placed either transversely (0 degrees) or placed caudodistally (30 degrees) with respect to the tibial tuberosity osteotomy. Each limb acted as its own respective control. Radiographic analysis allowed for the calculation of Kirschner wire insertion angle variance. Constructs were tested to monotonic failure while evaluating yield, peak, and failure forces, construct stiffness, and failure mode. RESULTS: Kirschner wire insertion angles were 1.1 ± 2.2 degrees and 30.5 ± 2.3 degrees, respectively, for 0-degree and 30-degree groups (p <0.0001). Yield (p = 0.0095), peak (p <0.024) and failure loads (p <0.030) were all significantly greater for Kirschner wires inserted at an angle of 0 degrees compared with 30 degrees. Construct stiffness did not differ regardless of insertion angle (p = 0.068). Failure mode did not differ (p = 0.87) with tibial tuberosity avulsion and Kirschner wire pull-out seen in the majority of constructs (67%). CONCLUSION: Kirschner wires placed transversely (0 degrees) for tibial tuberosity osteotomy fixation were biomechanically superior, increasing yield, peak, and failure forces by 1.6 times, 1.3 times, and 1.4 times, respectively, to those placed in a caudodistal (30 degrees) orientation. Kirschner wire insertion angle is an important consideration following tibial tuberosity osteotomy in dogs, with Kirschner wires placed at 0 degrees conferring increased resistance of the repair to construct deformation.

Comparison of outcomes across low-intensity psychological interventions for depression and anxiety within a stepped-care setting: A naturalistic cohort study using propensity score modelling.

Low-intensity interventions for common mental disorders (CMD) address issues such as clinician shortages and barriers to accessing care. However, there is a lack of research into their comparative effectiveness in routine care. We aimed to compare treatment effects of three such interventions, utilizing four years' worth of routine clinical data. Users completing a course of guided self-help bibliotherapy (GSH), internet-delivered cognitive behavioural therapy (iCBT) or psychoeducational group therapy (PGT) from a stepped-care service within the NHS in England were included. Propensity score models (stratification and weighting) were used to control for allocation bias and determine average treatment effect (ATE) between the interventions. 21,215 users comprised the study sample (GSH = 12,896, iCBT = 6862, PGT = 1457). Adherence-to-treatment rates were higher in iCBT. All interventions showed significant improvements in depression (PHQ-9), anxiety (GAD-7) and functioning (WSAS) scores, with largest effect sizes for iCBT. Both propensity score models showed a significant ATE in favour of iCBT versus GSH and PGT, and in favour of GSH versus PGT. Discernible differences in effectiveness were seen for iCBT in comparison with GSH and PGT. Given variance in delivery mode and human resources between different low-intensity interventions, building on these findings would be valuable for future service provision and policy decision making.

The relationship between posttherapeutic Cognitive Behavior Therapy skills usage and follow-up outcomes of internet-delivered Cognitive Behavior Therapy.

BACKGROUND: Clients independently applying Cognitive Behavior Therapy (CBT) skills is an important outcome of CBT-based treatments. The relationship between posttherapeutic CBT skills usage and clinical outcomes remains under-researched-especially after internet-delivered CBT (iCBT). OBJECTIVE: Explore contemporaneous and lagged effects of posttherapeutic CBT skills usage frequency on iCBT follow-up outcomes. METHOD: Nested within a randomized controlled trial, 241 participants received 8-week supported iCBT for anxiety and/or depression, completing measures of anxiety, depression, functional impairment, and CBT skills usage frequency at 3-, 6-, 9-, and 12-month follow-up. Cross-lagged panel models evaluated primary aims. RESULTS: While analyses support a contemporaneous relationship between anxiety, depression, functional impairment, and CBT skills usage frequency, no consistent lagged effects were observed. CONCLUSION: Findings align with qualitative research but the role of CBT skills usage in the maintenance of iCBT effects remains unclear. Innovative research modeling temporal and possibly circular relationships between CBT skill usage and clinical outcomes is needed to inform iCBT optimization.

Point-of-care viscoelastic coagulation assessment in healthy dogs during the perianesthetic period.

BACKGROUND: The viscoelastic coagulation monitor (VCM Vet) is a novel, portable device that provides a global assessment of hemostasis. The study aims were to evaluate serial viscoelastic analysis during the perianesthetic period in healthy dogs and to compare the agreement between two VCM Vet devices. Twenty healthy dogs undergoing orthopedic surgery were enrolled. Whole blood samples were collected from an intravenous catheter at four time points: baseline, 15 min after premedication, 60 min after inhalant initiation, and 60 min after inhalant termination. Viscoelastic tests were performed in duplicate on different devices, providing: clot time (CT; seconds), clot formation time (CFT; seconds), alpha angle (α; degrees), amplitude (units) at 10 (A10) and 20 (A20) minutes post clot time, maximum clot firmness (MCF; units), and lysis index (%) at 30 (Li30) and 45 (Li45) minutes post maximum clot formation. RESULTS: One hundred sixty samples were analyzed. The speed of CT and CFT significantly decreased an average of 25.5 s (95% confidence interval [CI]15.9-35.0) and 6.9 s (95% CI 3.1-10.7) per time point, respectively. There were no significant changes in clot strength or lysis variables. The Bland-Altman style plot shows an acceptable rate of agreement for all variables with intra-class correlation ranging from 0.64-0.94. CONCLUSION: The rate of clot formation (CT and CFT) decreased over the perianesthetic period in healthy dogs undergoing surgery. These changes were small and occurred without changes in clot strength or fibrinolysis rate, thus were not clinically relevant. There was clinically acceptable consistency between devices.

Effect of epitendinous suture augmentation to a double Krackow suture pattern for canine gastrocnemius tendon repair.

OBJECTIVE: To evaluate the effect of a double Krackow suture pattern (DK), with and without epitendinous suture augmentation (ES), in a canine gastrocnemius tendon (GT) model. SAMPLE: Paired GTs from 12 adult dog cadavers and 4 control GT. PROCEDURES: GTs were assigned to 2 groups (n = 12/group). Transverse tenotomy was performed and repaired with a DK or DK + ES. Yield, peak, and failure force, stiffness, occurrence of 1-and 3-mm gapping, and failure mode were examined. RESULTS: Yield, peak, and failure loads were greater for DK + ES. Yield force was 48% greater for DK + ES (mean ± SD, 149.56 ± 53.26 N) versus DK (101.27 ± 37.17 N; P = 0.017). Peak force was 45% greater for DK + ES P < 0.001). Failure force was 47% greater for DK + ES (193.752 ± 31.43 N) versus DK (131.54 ± 22.28 N; P < 0.001). Construct stiffness was 36% greater for DK + ES (P = 0.04). All 12 DK and 10 of 12 DK + ES repairs produced a 1-mm gap, with all DK and 4 DK + ES repairs producing a 3-mm gap (P < 0.001). Loads required to create a 3-mm gap were significantly greater for DK + ES (P < 0.013). Suture breakage occurred in all DK repairs, which differed from DK + ES, where suture breakage (7/12) and tissue failure (5/12; P = 0.037) predominated. CLINICAL RELEVANCE: Augmentation of a primary DK repair with an ES significantly improved construct strength in canine GT constructs while increasing loads required to cause 1- and 3-mm gap formation, respectively. ES augmentation is a simple technique modification that can be used to significantly increase construct strength, compared with DK alone.

Loop diameter of a modified Kessler locking-loop suture affects in vitro tensile strength and gapping characteristics of canine flexor tendon repairs.

OBJECTIVE: To evaluate effects of loop diameter of a modified Kessler locking-loop (LL) suture on in vitro tensile strength and gapping characteristics of canine flexor tendon repairs. SAMPLE: 48 cadaveric superficial digital flexor tendons from 24 adult medium- to large-breed dogs. PROCEDURES: Flexor tendons were randomly assigned to 4 groups (n = 12/group) and repaired with 2-0 polypropylene in a LL pattern with loops measuring 1, 2, 3, or 4 mm in diameter. Biomechanical loads, gap formation between tendon ends, and failure modes were evaluated and compared between groups. RESULTS: Increasing loop diameter from 1 to 4 mm significantly increased yield (P = .048), peak (P < .001), and failure (P < .001) loads. There were no significant differences in yield, peak, and failure loads between 1- and 2-mm loops. Load to 3-mm gap formation was significantly (P < .001) greater for 4-mm loops, compared with 1-, 2-, and 3-mm loops. Failure mode did not differ significantly among experimental groups, with 46 of 48 (96%) of constructs failing because of suture breakage. CLINICAL RELEVANCE: Loop diameter of a LL suture pattern is an important biomechanical variable that influences construct biomechanics of canine tendon suture repairs. Loop diameters > 3 mm are recommended when the size of the tendon allows. Further studies are necessary to determine the in vivo effect of these findings, particularly the effects on tendon blood supply.

Superficial digital flexor tendon graft augmentation improves the tensile strength and resistance to gap formation following primary gastrocnemius tendon repair in dogs.

OBJECTIVE: To evaluate the influence of superficial digital flexor tendon (SDFT) graft augmentation on the biomechanical properties and resistance to gap formation in a canine gastrocnemius tendon repair model. SAMPLE POPULATION: 28 canine cadaveric hind limbs. PROCEDURES: Respective hindlimbs from each dog were randomized to one of two groups (n = 14/group) using a 3-loop-pulley (3LP) pattern alone or 3LP + SDFT graft augmentation. Biomechanical parameters evaluated included yield, peak, and failure loads; tensile loads required to create 1- and 3-mm gap formations; and mode of construct failure. RESULTS: Mean yield and failure loads for the 3LP + SDFT graft group were 483.6 ± 148.0 N and 478.3 ± 147.9 N, respectively, and were greater compared to the 3LP group (34.2 ± 6.7 N and 34.0 ± 8.0 N, P < .0001). Loads to both 1- and 3-mm gap formations for the 3LP + SDFT graft group were greater compared to 3LP alone (P < .001). Failure modes did not differ between groups (P = .120), with constructs failing most commonly by suture pulling through opposed tendinous tissues whereas SDFT grafts remained intact. CLINICAL RELEVANCE: SDFT graft augmentation increased yield, peak, and failure forces 14-fold across all examined biomechanical variables compared to the 3LP group. The 3LP + SDFT graft group required 3.6X and 6.5X greater loads to cause a 1- and 3-mm gap, respectively, between tendon ends. These data support the biomechanical advantages of SDFT graft augmentation to increase repair-site strength and to promote resistance to gap formation of the tenorrhaphy. Additional in vivo studies are required to determine the effect of SDFT augmentation on clinical function and active limb use after graft harvest in dogs.

Loop modification of the traditional three-loop pulley pattern improves the biomechanical properties and resistance to 3-mm gap formation in a canine common calcanean teno-osseous avulsion model.

OBJECTIVE: To compare the biomechanical properties and gapping characteristics following loop modification of a 3-loop-pulley (3LP) pattern in an ex vivo canine common calcaneal tendon (CCT) avulsion repair model. SAMPLE: 56 skeletally mature hindlimbs from 28 canine cadavers. PROCEDURES: The CCTs were randomized to 1 of 4 experimental groups (n = 14/group) then sharply transected at the teno-osseous junction. Groups consisted of a 3LP, 4-loop-pulley (4LP), 5-loop-pulley (5LP), or 6-loop-pulley (6LP) pattern with loops placed 60° apart using size-0 polypropylene. Yield, peak, and failure loads, construct stiffness, loads to produce a 3-mm teno-osseous gap, and failure mode were evaluated and compared between groups. RESULTS: Yield (P = 0.001), peak (P < 0.001), and failure loads (P < 0.001), construct stiffness (P < 0.001), and loads to 3-mm gap formation (P = 0.005) were all significantly greater for 6LP compared to all other groups. Mode of failure did not differ among groups (P = 0.733) with 75% (42/56) of repairs failing by mechanism of core sutures pulling through the tendinous tissue. Pattern modification by increasing the number of loops increased the repair site strength by 1.4, 1.6, and 1.8 times for 4LP, 5LP, and 6LP compared to 3LP, respectively. CLINICAL RELEVANCE: Increasing the number of suture loops compared to a traditional 3LP repair is a relatively simple technique modification that significantly increases teno-osseous repair site strength and loads required to cause 3-mm gap formation. The results of this study justify further focused investigation of increasing the number of suture loops in vivo for teno-osseous CCT repair in dogs.

Interfacial metric mechanics: stitching patterns of shape change in active sheets.

A flat sheet programmed with a planar pattern of spontaneous shape change will morph into a curved surface. Such metric mechanics is seen in growing biological sheets, and may be engineered in actuating soft matter sheets such as phase-changing liquid crystal elastomers (LCEs), swelling gels and inflating baromorphs. Here, we show how to combine multiple patterns in a sheet by stitching regions of different shape changes together piecewise along interfaces. This approach allows simple patterns to be used as building blocks, and enables the design of multi-material or active/passive sheets. We give a general condition for an interface to be geometrically compatible, and explore its consequences for LCE/LCE, gel/gel and active/passive interfaces. In contraction/elongation systems such as LCEs, we find an infinite set of compatible interfaces between any pair of patterns along which the metric is discontinuous, and a finite number across which the metric is continuous. As an example, we find all possible interfaces between pairs of LCE logarithmic spiral patterns. By contrast, in isotropic systems such as swelling gels, only a finite number of continuous interfaces are available, greatly limiting the potential of stitching. In both continuous and discontinuous cases, we find the stitched interfaces generically carry singular Gaussian curvature, leading to intrinsically curved folds in the actuated surface. We give a general expression for the distribution of this curvature, and a more specialized form for interfaces in LCE patterns. The interfaces thus also have rich geometric and mechanical properties in their own right.

Influence of barbed suture oversew of the transverse staple line during functional end-to-end stapled anastomosis in a canine jejunal enterectomy model.

OBJECTIVE: To evaluate the influence of barbed suture oversew of the transverse staple line during functional end-to-end stapled anastomosis (FEESA) in dogs. STUDY DESIGN: Randomized, experimental, ex vivo. ANIMALS OR SAMPLE POPULATION: Grossly normal jejunal segments from 14 adult canine cadavers. METHODS: Ninety-eight jejunal segments (n = 14/FEESA group, n = 14 controls) were harvested and randomly assigned to a control group, FEESA + monofilament suture oversew, FEESA + unidirectional barbed suture oversew or FEESA + bidirectional barbed suture oversew. Oversew techniques were performed using a Cushing suture pattern. Initial (ILP) and maximum leakage pressure (MLP), repair time (s), and location of observed leakage were recorded. RESULTS: No differences were detected in ILP (p = .439) or MLP (p = .644) respectively between experimental groups. Repairs times using barbed suture were ~ 18% faster (~25 s faster; p < .001) compared to monofilament suture. There was no difference between barbed suture types (p = .697). Mean ILP (p < .001) and MLP (p < .0001) were 6.6x and 5.1x greater respectively in the control group. Leakage location occurred predominately at the crotch of the FEESA in all groups. CONCLUSION: FEESAs closed with a transverse staple line oversew using barbed suture, regardless of barb orientation, were completed faster and resulted in similar resistance to anastomotic leakage compared to monofilament suture. CLINICAL SIGNIFICANCE: Oversewing the transverse staple line following FEESA using barbed suture offers similar resistance to anastomotic leakage, and may be associated with decreased surgical times in dogs compared to monofilament suture. Further studies are necessary to determine the benefits of barbed suture use in both open and laparoscopic gastrointestinal surgical applications following FEESA in dogs.