Repair Strength Research Articles

Development of pipe repairs using bonded metal plate – Part I: Shape factor, stiffness and surface treatment

This work aims to study the resistance of repairs with bonded plates in pipes with holes subjected to hydrostatic pressure. It is a promising alternative for application in low-risk repairs (up to 1 MPa). Due to the differences between the circumferential and transverse stresses in the pipes, the influence of the bonded plate area in the joint strength was evaluated, checking whether the shape factor occurs. The effect of plate thickness in the repair strength, besides the addition of silane on the plate surfaces, were also studied. Finally, considering a control plate based in the performed experiments, the surface treatment influence on the tubes was evaluated in the face of rupture pressure of the system. High hydrostatic resistance values were found, demonstrating the efficiency of the procedures used in the repair. The studies show little influence on the repair strength due to dimensions variation in different directions, and high influence on the surface treatment, stiffness and bonded area increase. The work aims to initiate the development of a new procedure for contingency repair with low risk.

Entropy and interfacial energy driven self-healable polymers

Although significant advances have been achieved in dynamic reversible covalent and non-covalent bonding chemistries for self-healing polymers, an ultimate goal is to create high strength and stiffness commodity materials capable of repair without intervention under ambient conditions. Here we report the development of mechanically robust thermoplastic polyurethane fibers and films capable of autonomous self-healing under ambient conditions. Two mechanisms of self-healing are identified: viscoelastic shape memory (VESM) driven by conformational entropic energy stored during mechanical damage, and surface energy/tension that drives the reduction of newly generated surface areas created upon damage by shallowing and widening wounds until healed. The type of self-healing mechanism is molecular weight dependent. To the best of our knowledge these materials represent the strongest (Sf = 21 mN/tex, or σf ≈ 22 MPa) and stiffest (J = 300 mN/tex, or E ≈ 320 MPa) self-healing polymers able to repair under typical ambient conditions without intervention. Since two autonomous self-healing mechanisms result from viscoelastic behavior not specific to a particular polymer chemistry, they may serve as general approaches to design of other self-repairing commodity polymers.

Bonding repair of CFRP based on cold plasma treatment surface modification

The surface pretreatment before bonding repair determines the microscopic physical and chemical properties of the composites, and directly affects the bonding strength and maintenance effect. In this paper, the surface of the Carbon Fiber Reinforced Polymer (CFRP) was pretreated by Cold Plasma Treatment (CPT) under 2.5 times air atmosphere (0.25 MPa) to achieve the best interface micro-performance for bonding repair. Based on the surface microstructure and surface activity test, the single lap test was used to evaluate the bonding repair strength after surface modification. The results show that the optimized surface treatment parameters of the output power, the plasma flame-core distance, and the process time were 800 W, 7 mm, and 7 s, respectively. It is found that no damage to the fiber and the surface-free energy of the pretreated composites (800 W, 7 mm, 7 s) reaches 51.65 mN/m under the optimized process, which is higher than those of the untreated original value 43.83 mN/m and the manual-grinding treatment value 45.73 mN/m. The bonding strength of CFRP after CPT treatment was increased to 11.31 MPa, which was obviously better than the bonding strength of 7.11 MPa without pretreated specimen and the bonding strength of 8.14 MPa after manual-grinding treatment. The failure mode of samples after CPT treatment was cohesive failure, while those of manual-grinding treated and original untreated CFRP samples exhibited thin layer cohesive failure (TLC) and adhesion failure (ADH), respectively.

Helical 6-Strand Cruciate Tenorrhaphy: Description of a New Technique and Biomechanical Comparative Analysis With 2 Standard Techniques.

Background: Multiple flexor tendon repair techniques have been developed over the last years. Despite all this, there is no standard technique that has proven to be superior to others, leading to great variability in the use of techniques in surgical practice. We describe a novel tendon repair technique and compare its biomechanical characteristics with 2 conventional techniques. Methods: Comparative experimental biomechanical study in ex vivo animal models. In all, 66 deep flexor tendons of the pig's front legs were taken and it's repair was performed by 1 of 3 techniques (helical 6-strand cruciate tendon repair, Adelaide tendon repair, or modified Kessler). These repairs were subjected to biomechanical study, measuring, and registering the ultimate tensile strength, load to 2-mm gap force, and stiffness. Results: The helical 6-strand cruciate tenorrhaphy compared with the Adelaide and modified Kessler techniques carries statistically significant greater ultimate tensile strength before failure (65.5, 46, and 36 N, respectively, P < .001). It also required a greater load to 2-mm gap force and is less stiff, allowing greater strain before failure. This technique does not generate significant changes in the dimensions of the tendons compared to the others, and there was no significant difference in the strength of repair between surgeons. Conclusions: The helical 6-strand cruciate tenorrhaphy is a novel technique, useful for the repair of flexor tendons in the hand that holds up the necessary forces to initiate early mobilization in the postoperative period and has better biomechanical properties than 2 standard techniques.

Effect of Cyclic Loading on the Strength of Flexor Tendon Repair in Vitro Study

Background: The initial strength of the repair depends on the material properties and knot security of the sutures as well as on the holding capacity of the suture grip of the tendon. Objective: Detecting the effect of cyclic loading on the strength of flexor tendon repair using 6 strand Tang suture experimentally. Materials and Methods: In the present ex vivo study of 50 sheep flexor tendons, six strand Tang suture technique was used: Twenty five repairs were subjected to cyclic tensile testing, and twenty five repairs were subjected to static tensile testing using 4/0 polypropylene simple suture material + epitendinous continuous running sutures using 5/0 polypropylene suture material. Results: The results of the study showed that 44 % survival at 41.7 N cyclic testing, without evidence of significant gap formation or rupture and the breaking force on continuous loading mean 55.95 N. The Tang suture method provided much more sufficient gap resistance and tensile strength able to withstand early active mobilization after primary flexor tendon repair. Conclusion: The Tang suture method provided sufficient gap resistance and tensile strength able to withstand early active mobilization after primary flexor tendon repair. There were some disadvantages regarding to time consuming during surgery and difficult to use in pediatrics and small tendons.

Repair strength and surface topography of lithium disilicate and hybrid resin ceramics with LLLT and photodynamic therapy in comparison to hydrofluoric acid.

The aim was to compare the repair bond strength and surface topography of lithium disilicate ceramics (LDC) and hybrid resin ceramics (HRC) using different surface conditioning treatments [low level laser therapy (LLLT), photodynamic therapy (PDT), hydrofluoric acid (HF) with silane and air abrasion (AA) and silane]. Sixty specimens each of LDC and HRC were used. Discs were prepared for each group (6 × 2 mm), conditioned using different regimes. Specimens in group 1 and 5 were laser irradiated using Er,Cr:YSGG (ECYL), group 2 and 6 were conditioned using methylene blue photosensitizer (PDT), group 3 and 7 surface was treated with hydrofluoric acid and silane (HFA-S), group 4 and 8 conditioned with Al2O3 air abrasion and silane (AA-S). A Porcelain Repair Kit was used according to manufacturer recommendation in all samples. Peak universal bond adhesive was rubbed on ceramic surface and then bonded with composite resin. For shear bond strength testing the specimens were placed in a universal testing machine. A stereomicroscope at 40x magnification was used to analyse failure pattern. Five specimens in each group after surface treatment were evaluated for surface changes and topography using scanning electron microscopy. The mean repair bond strength was calculated using ANOVA and Tukey's post hoc test at a significance level of (p < 0.05). The highest repair bond strength was observed in group 3 (LDC) (20.57 ± 3.58 MPa) (HFA-S), whereas, the lowest score was displayed in Group 2 (LDC) using methylene blue photosensitizer (MBPS) (12.18 ± 1.08 MPa). Similarly, in HRC the highest repair SBS was presented in group 8 (AA-S) (20.52 ± 2.51 MPa) and the lowest SBS values were exhibited by PDT treated group 6 (13.22 ± 0.62 MPa). A combination of mechanical and chemical surface treatments should be used in order to achieve adequate repair bond strength between resin composites and ceramic interface of LDC and HRC.

Influence of artificial aging and ZrO2 nanoparticle-reinforced repair resin on the denture repair strength.

BackgroundThe purpose of this study was to evaluate the effect of aging process on the tensile strength (TS) of repaired acrylic denture base using ZrO2 nanoparticles (nano-ZrO2)-reinforced autopolymerized resin. Material and MethodsA total of 240 heat-polymerized acrylic resin specimens (n=10) were prepared and sectioned creating 2 mm-repair-gap. Autopolymerized acrylic resin, pure and modified with 2.5, 5, and 7.5wt% nano-ZrO2 were used for specimens repair. TS of repaired specimens were measured using the universal testing machine after water immersion at 37oC for 2, 7 and 30 days. At each time interval, half the immersed specimens underwent thermo-cycling aging process (5000 cycles at 5/55°C) before TS testing. One-way ANOVA and Tukey-Kramer multiple-comparison tests were used for data analysis at α=0.05. ResultsAging process for all groups showed significant differences in TS between unreinforced and nano-ZrO2 reinforced groups (p<0.05). Within immersed nano-ZrO2-reinforced specimens, 5% group immersed for 30-days showed the highest significant TS value (p<0.05). With regards to thermocycling, 5% group showed the highest TS values after 2-days and 30-days groups while after 7-days, significant differences were found between 2.5% group and 5% and 7.5% groups (p<0.05). SEM images analysis displayed the ductile fracture type for nano-ZrO2 reinforced groups. ConclusionsIn summary, 5.0%-nano-ZrO2 addition to repair resin showed an improvement in tensile strength of repaired acrylic resin with different aging processes. Key words:Acrylic resins, denture repair, tensile strength, thermocycling, water storage, zirconium oxide nanoparticle.

Influence of Surface Conditioning on the Repair Strength of Bioactive Restorative Material.

To evaluate the effects of surface treatment and repair material on the repair shear bond strength (SBS) of the bioactive restorative material. A total of 240 Activa BioActive Restorative (Activa) discs were prepared, aged, and polished, and divided randomly into eight groups (n = 30). Groups 1-4 discs were repaired with bulk-fill flowable resin-based composite (Bulk-RBC), and Groups 5-8 discs with Activa. Surface treatment used for each repair material type were air abrasion with silica-coated 30-m Al2O3 particles (air abrasion) (Groups 2 & 6), Air abrasion with universal primer (Groups 3 & 7), and Air abrasion with universal adhesive (Groups 4 & 8). Groups 1 and 5 were controls without surface treatment. SBS test was performed, and the failure mode and surface topography were assessed. Surface treatment with air abrasion significantly improved the SBS for repair using both Activa and Bulk-RBC. Repair SBS using Activa was significantly higher compared with Bulk-RBC. Cohesive failure in substrate and mixed failures were most common in the surface-treated groups (2-4, 6-8). Air abrasion produced prominent surface topography changes compared with polishing. Air abrasion enhances the repair SBS of aged bioactive restorative material. The use of the same material (Activa) for repair affords a higher bond strength compared with the use bulk-RBC.

Repair Bond Strength of a CAD/CAM Nanoceramic Resin and Direct Composite Resin: Effect of Aging and Surface Conditioning Methods.

To evaluate the effect of surface conditioning methods and aging on the repair bond strength between resin composite and nanoceramic CAD/CAM resin. Twenty-four blocks of nanoceramic CAD/CAM resin (NCR) (Lava Ultimate, 3M Oral Care) (10 x 5 x 2 mm3) and resin composite (Filtek Z350, 3M Oral Care) (RC) were made, embedded in acrylic resin, polished (#600, #800, #1200) and randomly divided into 8 groups (n = 12 each) according to surface conditioning methods (air abrasion with 30-μm CoJet [CJ] or air abrasion with 50-μm Al2O3 [AB]) and aging prior to repair (without aging, 24 h in water at 37°C; with aging 6 months in water at 37°C). The blocks were air abraded (20 s, 2.5 bar, 10 mm) using a standardized device. A layer of adhesive resin (Scotchbond Universal) was applied (20 s) and photopolymerized for 20 s. RC cylinders (Ø = 2 mm; h = 2 mm) were then bonded to the NCR substrates using a Teflon matrix and photopolymerized for 40 s. All specimens were thermocycled (10,000 cycles, 5°C-55°C) and submitted to the shear bond test (50 kgf, 0.5 mm/min) to measure repair strength. Data (MPa) were analyzed using 3-way ANOVA and Tukey's test (α = 0.05). Failure analysis was performed using stereomicroscopy (20X). ANOVA revealed a significant effect of only the "material" factor (p = 0.00). The group NCR6mCJ presented bond strengths (29.37 ± 5.41) which were significantly higher than those of the NCR24hCJ (20.88 ± 5.74) and RC groups (p < 0.05). The group RC24hCJ (19.71 ± 4.21) presented the lowest shear bond strength (p < 0.05). Failure analysis revealed predominantly type B mixed failures (adhesive+cohesive in the substrate material) except for the groups NCR24hCJ and NCR6mAB, where mainly type C failure (adhesive+cohesive at the RC) was observed. Air abrasion with Al2O3 particles or silicatization with CoJet followed by adhesive resin application are effective surface conditioning methods for the repair of nanoceramic CAD/CAM resin with resin composite.

Effect of thermal cycling on temperature changes and bond strength in different test specimens

Objectives To investigate temperature changes in various test specimens during thermal cycling and to evaluate difference in micro-tensile repair bond strength in specimens cut from the inner or the outer area of composite blocks after thermal cycling. Materials and methods Four rectangular composite blocks of various sizes were fabricated, and thermocouples placed in the centre of the specimens or halfway from the surface to the centre. Composite cylinders were made on ground flat extracted molars, as intended for micro-tensile and shear bond testing, with a thermocouple placed at the centre of the cylinder radius between composite and dentin. The specimens were thermal cycled between 5 °C and 55 °C with 20–60 s dwell times. The highest and lowest temperatures in the test specimens were recorded. Composite blocks were fabricated and stored in water for a week and then repaired with the same composite. After thermal cycling (5000×, 5 °C and 55 °C with a 20 s dwell time), test specimens were cut for micro-tensile testing. Results None of the specimens tested reached the cold and warm water bath temperatures after a 20 s dwell time. In the smallest composite block, the centre core temperature reached 5 °C and 55 °C after 40 s dwell time, but lacked 1 °C after 60 s in the largest block. None of the specimens involving teeth reached water temperatures. The micro-tensile repair strength was significantly different between the outer and the central cut rods (p < .05). Conclusions The most commonly used dwell times for thermal cycling are insufficient to create a homogeneous temperature change.

Meniscus-Derived Matrix Bioscaffolds: Effects of Concentration and Cross-Linking on Meniscus Cellular Responses and Tissue Repair.

Meniscal injuries, particularly in the avascular zone, have a low propensity for healing and are associated with the development of osteoarthritis. Current meniscal repair techniques are limited to specific tear types and have significant risk for failure. In previous work, we demonstrated the ability of meniscus-derived matrix (MDM) scaffolds to augment the integration and repair of an in vitro meniscus defect. The objective of this study was to determine the effects of percent composition and dehydrothermal (DHT) or genipin cross-linking of MDM bioscaffolds on primary meniscus cellular responses and integrative meniscus repair. In all scaffolds, the porous microenvironment allowed for exogenous cell infiltration and proliferation, as well as endogenous meniscus cell migration. The genipin cross-linked scaffolds promoted extracellular matrix (ECM) deposition and/or retention. The shear strength of integrative meniscus repair was improved with increasing percentages of MDM and genipin cross-linking. Overall, the 16% genipin cross-linked scaffolds were most effective at enhancing integrative meniscus repair. The ability of the genipin cross-linked scaffolds to attract endogenous meniscus cells, promote glycosaminoglycan and collagen deposition, and enhance integrative meniscus repair reveals that these MDM scaffolds are promising tools to augment meniscus healing.

Efficacy of different surface treatments and universal adhesives on the microtensile bond strength of bulk-fill composite repair

The purpose of this in vitro study was to evaluate the influence of different surface treatments and aging on the microtensile bond strength (μTBS) of bulk-fill composite resins. Bulk-fill composites (Filtek One; 3M ESPE) randomly received five different surface treatments: (1) no treatment, control, (2) 37% phosphoric acid etching (PA), (3) 9% hydrofluoric acid etching (HF), (4) air-borne particle abrasion with 50-μm alumina particles (Al2O3), (5) tribochemical silica coating (CoJet). Following, the specimens were divided into three subgroups according to universal adhesive applied: Clearfil Universal Bond (CU; Kuraray), Prime&Bond Universal (PBU; Dentsply Sirona), or Single Bond Universal (SBU; 3M ESPE). A nanofill composite (Filtek Ultimate; 3M ESPE) was employed as a repair. Bonded specimens were stored in water for 24 h at 37 °C or thermal aged, then subjected to the μTBS test. Additionally, specimens were analyzed with a contact profilometer and were evaluated with scanning electron microscopy. Control and PA treatments were showed the lowest µTBS (p < 0.05), and there was no significant difference between these two groups (p > 0.05). Al2O3 and CoJet treatments generally exhibited a similar influence on µTBS values. In addition, a correlation was found between surface roughness and bond strength (r = 0.831). CoJet resulted in significantly higher repair µTBS values when compared to the other surface treatments. In addition, the use of silane-containing universal adhesive was increased the cohesive failure rate and maintained the repair µTBS values after thermocycling.

Hernia Repair Strength Enhanced With Antioxidants

BackgroundIncisional hernia is one of the most common complications of abdominal surgery, and repairs are associated with significant recurrence rates. Mesh repairs are associated with the best outcomes, but failures are not uncommon. Doxycycline has been demonstrated to enhance mesh hernia repair outcomes with associated increases in collagen deposition and improved tensiometric strength. This study compares the outcomes of incisional hernia repair with doxycycline administration and the antioxidant tempol. Materials and methodsTwenty-eight male Sprague Dawley rats underwent a midline hernia creation and an intraabdominal polypropylene mesh repair. The animals were administered saline, doxycycline, tempol, or both, daily for 8 wk. The abdominal wall was harvested at 8 wk and tensiometric strength and biochemical analysis was performed. ResultsThe tensiometric strength of the repair was increased in all experimental groups. Collagen type 1 deposition was increased, and collagen type 3 deposition was decreased in each of the experimental groups relative to control. There was no difference in MMP-2 and MMP-9 levels between control and experimental groups. ConclusionsThe hernia repair strength is equally enhanced with the administration of doxycycline or tempol. Dual therapy provided no benefit over treatment with either single agent. All treatment groups had an increase in collagen type 1:3 ratios, but the mechanism is not well understood. The benefits of antioxidant treatment following hernia repair are similar to treatment with doxycycline. Given the high frequency of incisional hernia repair failures, this study has implications for improving outcomes following ventral hernia repair through the use of either doxycycline or antioxidant therapy.

Comparative Effect of Glass Fiber and Nano-Filler Addition on Denture Repair Strength.

To evaluate and compare the effects of glass fiber (GF), Zirconium oxide nanoparticles (nano-ZrO2 ), and silicon dioxide nanoparticles (nano-SiO2 ) addition on the flexural strength and impact strength of repaired denture base material. Heat-polymerized acrylic resin specimens were fabricated. All specimens were sectioned centrally and beveled creating 2.5 mm repair gap except for 10 controls. Specimen grouping (n = 10/group) was done according to filler concentration of 0%, 0.25%, 0.5%, and 0.75% of auto-polymerized acrylic powder. Modified resin was mixed, packed in the repair gap, polymerized, finished and polished. Three-point bending test and Charpy type impact testing were done. Data were analyzed using one-way-ANOVA and Post-Hoc Tukey test (α = 0.05). All additives significantly increased flexural strength and impact strength (p < 0.05). Within the modified subgroups, no significant differences were found for GF. Significant increase for nano-ZrO2 and significant decrease for nano-SiO2 as the concentration of additive increased were noted for both flexural strength and impact strength. Highest flexural strength was found with 0.75%-nano-ZrO2 (69.59 ± 2.52MPa) and the lowest was found with 0.75%-nano-SiO2 (53.82 ± 3.10MPa). The 0.25%-nano-SiO2 showed the highest impact strength value (2.54 ± 0.21 kJ/m2 ) while the lowest impact strength value was seen with 0.75%-nano-SiO2 (1.54 ± 0.17 kJ/m2 ). Nano-filler effect was concentration dependent and its addition to repair resin increased the flexural and impact strengths. The incorporation of 0.75%-ZrO2 or 0.25%-SiO2 into repair resin proved to be a promising technique to enhance repair strength and avoid repeated fractures.

Biomechanical Comparison of the Long Head of the Biceps Tendon Versus Conjoint Tendon Transfer in a Bone Loss Shoulder Instability Model.

Background:Augmentation of Bankart repair with long head of the biceps tendon transfer has been previously described, although there is a paucity of literature describing its biomechanical effects.Purpose/Hypothesis:The purpose of this study was to assess the effect of augmenting Bankart repair with either the conjoint tendon or the long head of the biceps tendon, both with and without subcritical (13%) glenoid bone loss. We hypothesized that, in a cadaveric model, augmenting Bankart repair with the long head of the biceps tendon would restore a greater degree of stability compared with augmenting Bankart repair with the conjoint tendon.Study Design:Controlled laboratory study.Methods:A total of 12 cadaveric shoulders were tested on a 6-degrees-of-freedom robotic musculoskeletal simulator to measure the peak resistance force due to an anterior displacement of 1 cm. The rotator cuff muscles were loaded during testing to simulate physiological conditions. The following test conditions were used for each specimen: (1) intact shoulder, (2) Bankart lesion with 13% anterior bone loss, (3) 13% bone loss with Bankart repair (anchors placed at the 3-, 4-, and 5-o’clock positions), (4) 13% bone loss with both Bankart repair and transfer of the long head of the biceps tendon, and (5) 13% bone loss with Bankart repair and transfer of the conjoint tendon.Results:Labral repair with the addition of long head of the biceps tendon transfer had the greatest peak resistance force to anterior displacement among all groups (54.1 ± 5.5 N) and was significantly stronger than both standard Bankart repair by 16.3% (46.5 ± 7.6 N; P = .039) and the conjoint transfer procedure by 16.6% (46.4 ± 7.7 N; P = .008).Conclusion:Given the susceptibility of recurrent instability in shoulders with subcritical bone loss after isolated labral repair, it is important to consider augmenting Bankart repair in high-risk patients to avoid potential recurrence and the need for reoperations. Transferring the long head of the biceps tendon to the anterior glenoid represents one possible augmentation.Clinical Relevance:We present biomechanical data for a relatively novel technique for augmenting capsulolabral repair strength in an anterior instability model with subcritical bone loss. These data represent biomechanical justification for the utilization of this relatively novel technique.

Comparison of tensile strength of continues-core method and 4 strand modifies method of after healing of repaired Kessler rabbit’s Achilles tendon injury

Tendon injury causes significant morbidity during the productive age, and the number is increase in recent decades. Tensile strength is the most important factor in tendon function of style, and the results of repair should be able to withstand large current style of early mobilization. This research was an experimental research design with the post-test only control group design with the subject of the rabbit. A total of 18 research subjects who meet the requirements of the study inclusion were randomly divided into treatment and control groups. Control group was a group of rabbits that were repaired with 4 strand modified Kessler technique after Achilles tendon cut sharply. While the treatment group were a group of rabbits that were repaired with continuous-cores technique. The ratio of collagen I/III in rabbit Achilles tendon repair with the technique of continuous-cores are smaller compared to the control group with value of P <0.05. Also Showed statistical analysis tensile strength of rabbit Achilles tendon repair with the technique of continuous-core is greater than the control group at P <0.05.

Proximal and Distal Failure Site Analysis in Percutaneous Achilles Tendon Rupture Repair

Category:AnkleIntroduction/Purpose:Different techniques have been described for Achilles Tendon Rupture repair, but no biomechanical evaluation have been performed separately for proximal and distal suturing techniques.The purpose of this study was to biomechanically analyze 3 proximal and 2 distal suture configurations during a simulated cyclic load and load to failure. It was hypothesized that proximal suturing technique was stronger than the distal one and that the modified double suturing technique was the strongest of all techniques.Methods:A simulated, mid-substance rupture was created 6 cm proximal to the calcaneal insertion in 15 fresh-frozen cadaveric Achilles tendons, obtaining 15 proximal and 12 distal samples. Specimens were tested independently and randomly allocated to different suture techniques: proximal fixation site groups: (A1) classic Dresden technique, (A2) modified Dresden, (A3) double modified Dresden; distal fixation groups: (B1) classic distal suture and (B2) modified distal suture. Repairs were subjected to a cyclic testing (1000 cycles of 50-200 N) and load to failure. Load to failure, cause of failure and tendon elongation was evaluated. Fischer’s test was used as statistical analysis.Results:None of the proximal tendon and 7/12 of the distal samples failed in cyclic testing. The proximal fixation groups demonstrated significantly more strength than the distal groups (p< 0.05) with average failure loads of 598 N, 587 N and 710 N for groups A1, A2 and A3 respectively (A3 stronger than A1 and A2, p=0,035). Groups B1 and B2 failed on average at 416 N and 351 N respectively, p=0.24. The majority of all repairs failed in the suture- tendon interphase.Regarding elongation, no significant differences were found between groups (p=0.57).Conclusion:The distal fixation site in the Dresden percutaneous Achilles tendon repair is weaker than the proximal fixation site. A proximal modified suture configuration increased resistance to cyclic loading and load to failure significantly. A modification in the proximal and distal fixation sites can be suggested to improve repair strength and hopefully achieve a better outcome.

A direct method for measuring surface area of polymer mesh using synchrotron x-radiation microComputed tomography: a pilot study

Mesh products are critical for successful long term surgical repair of many anatomic defects, including hernias and pelvic prolapse. Biocompatibility of polymeric mesh depends on the foreign body response- how the tissues react to physicochemical properties, including porosity and mesh ‘weight’. We postulate that effective surface area, the total filament area in contact with the tissues, is an important variable for long-term repair strength. We present a technique utilizing synchrotron x-radiation microComputed Tomography (microCT) to calculate the effective surface area of polymeric meshes. Six representative polypropylene-based hernia meshes, including composite meshes, were studied: Ethicon PROLENETM, Ethicon PROLENETMSoft Mesh, Ethicon PHYSIOMESHTM, Ethicon ULTRAPROTM, Atrium PROLITETM Mesh, and Bard® Soft Mesh. Ethicon PROLENETM , a heavy weight mesh, had the highest effective surface area at 6.44 cm2 cm−2 and Ethicon ULTRAPROTM, a composite light-weight mesh, had the lowest effective surface area at 0.62 cm2 cm−2. We conclude that this technique can reliably be used to further classify mesh, as manufacturers and surgeons continue to optimize the safety profile of these implants.

Effects of a Q Suture Technique on Resistance to Gap Formation and Tensile Strength of Repaired Tendons: An Ex Vivo Mechanical Study

The repair of digital flexor tendons following laceration should aim to prevent gapping at the repair site and restore the tensile strength of the tendons to facilitate postoperative movement. We present here a simple Q suture and test its effects on gap formation and tensile strength of the repaired tendons. Sixty porcine tendons were repaired with 3 2-strand sutures (Kessler, Kessler plus 2Q, and Kessler plus running sutures) and 3 4-strand sutures (double Kessler, double Kessler plus 2Q, and double Kessler plus running sutures). The specimens were subjected to a cyclic loading. At each cycle, the number of tendons that initiated gapping or formed a 2-mm gap at the repair site was determined. After the cyclic load testing, the gap distance between tendon ends and the ultimate strength of the repaired tendons was measured. In both 2-strand and 4-strand tendon repairs, augmentation by insertion of the 2Q sutures reduced the number of tendons that showed 2-mm gaps ends during loading. Compared with the single Kessler and Kessler plus running sutures, Kessler plus 2Q suture significantly increased the ultimate strength of the tendon repair. Compared with the double Kessler and double Kessler plus running sutures, double Kessler plus 2Q suture significantly decreased the gap distance at the repair site after cyclic loading. The Q suture technique effectively enhances the resistance to gap formation of 2-strand and 4-stand tendon repair. It also improves the tensile strength of 2-strand Kessler repairs. The Q suture is a simple technique that can resist gap formation and strengthen the tensile strength of the repaired tendons in the laboratory setting.

Portal Placement and Biomechanical Performance of Endoscopic Proximal Hamstring Repair

Background: Proximal hamstring tendon avulsions are debilitating and commonly cause pain, weakness, and functional limitations. Open surgical repair has been the standard, but improved endoscopic techniques have enabled proximal hamstring fixation with decreased risk of infection and numbness, without the morbidity of a large incision. Purpose/Hypothesis: The purpose was to (1) describe pertinent anatomy surrounding the proximal hamstring origin in relation to 4 endoscopic portal sites and (2) test for biomechanical differences between open and endoscopic repair. It was hypothesized that (1) endoscopic proximal hamstring repair is efficacious with respect to commonly used portals and (2) there is no biomechanical difference between open and endoscopic techniques. Study Design: Descriptive and controlled laboratory study. Methods: Proximal hamstring ruptures were simulated endoscopically in 10 fresh-frozen human cadaveric pelvis specimens. Endoscopic repair was then completed on 1 limb from each specimen through 4 portals. After repair, each specimen was dissected in layers and measurements from portal tracts to pertinent anatomy were obtained. Open repair was performed on all contralateral limbs, followed by cyclical biomechanical tensile testing to failure of both the open and endoscopically repaired hamstring tendons to assess failure load and local tissue strain. Results: On average, no portal tract was closer than 2.0 cm to the sciatic nerve or inferior gluteal neurovascular bundle. Anatomic landmarks were identified that could improve the reproducibility and safety of the procedure. Biomechanical testing revealed no differences between the open and endoscopic repair techniques for any measured parameter. Conclusion: This study supports the safety and efficacy of endoscopic proximal hamstring repair through anatomic and biomechanical analyses and helps establish reproducible and recognizable landmarks that define a safe working zone. Clinical Relevance: This study maps the anatomic landscape of the proximal hamstring as encountered endoscopically and demonstrates equivalent biomechanical strength of endoscopic proximal hamstring repair, supporting this technique’s safety and efficacy.