Barbed sutures versus conventional tenorrhaphy in flexor tendon repair: An ex vivo biomechanical analysis.

BACKGROUND: The management of flexor tendon injuries has evolved in recent years through industrial improvements in suture materials, refinements of repair methods, and early rehabilitation protocols. However, there is no consensus on the ideal suture material and technique. This study was conducted to compare the tensile strength, repair time, and characteristics of 4-strand cruciate, modified Kessler, and 4-strand horizontal intrafiber barbed sutures for flexor tenorrhaphy with a 12-mm suture purchase length in an animal model. METHODS: The right third deep flexors of 60 adult Leghorn chicken feet were isolated and repaired with a 12-mm suture purchase length. The tendons were randomly assigned to three groups of equal number (n=20 each). Groups 1 and 2 received 4-strand cruciate and modified Kessler repair with conventional suture materials, respectively. A 4-strand horizontal intrafiber barbed suture technique was used in group 3. The repaired tendons were biomechanically tested for tensile strength, 2-mm gap resistance, and mode of failure. Repair times were also recorded. RESULTS: The maximum tensile strength until failure was 44.6±4.3 N in group 1, 35.7±5.2 N in group 2, and 56.7±17.3 N in group 3. The barbed sutures were superior to the other sutures in terms of the load needed for 2-mm gap formation (P<0.05). Furthermore, the barbed sutures showed the shortest repair time (P<0.05). CONCLUSIONS: This study found that 4-strand horizontal intrafiber barbed suture repair with a 12-mm purchase length in a chicken flexor tendon injury model showed promising biomechanical properties and took less time to perform than other options.

Pulley reconstruction with different materials: experimental study.

The digital fibroosseous pulley system is essential for optimum function of the flexor tendons and the continuation of normal hand functions. Different materials have been used for pulley reconstruction in the literature but the ideal material is still controversial. In this study, after the excision of the A2 pulley, pulley reconstructions were performed by using acellular dermal matrix, solvent dehydrated bovine pericardium, fascia lata, and free tendon graft in the rabbit model. The animals were killed at the 8th and 12th weeks and subjected to biomechanical testing. Tendon excursion and work of flexion values were calculated for each digit of the rabbits. As a result, all the reconstructed pulleys were functioning well without a statistically significant difference between the experimental groups. Pulleys reconstructed with acellular dermal matrix and solvent-dehydrated bovine pericardium appear to have the potential to function as effective pulley substitutes.

Effects of resterilization on mechanical properties of polypropylene meshes.

BACKGROUND: The re-use of sterile packaged polypropylene meshes in hernia surgery is not recommended by the manufacturers. However, especially in developing and underdeveloped countries, many surgeons are obliged to re-use the mesh pieces after resterilization because of economic problems. The purpose of this study was to determine the effects of ethylene oxide and autoclave resterilization on the mechanical properties of polypropylene meshes. METHODS: Repetitive ethylene oxide gas and autoclave sterilizations were applied to polypropylene meshes (Herniamesh S.r.l., San Mauro, Italy) up to 3 times and the effects on the mechanical properties were examined. Gas resterilizations were applied for 4.5 hours at 55 degrees C, whereas for autoclave resterilizations the specimens were kept at 134 degrees C and 3 atm pressure for 64 minutes. Ethylene oxide gas-sterilized samples were labeled as G(n) and autoclave-sterilized samples were labeled as A(n). Effects of the resterilizations on maximum load (Fmax), elongation at maximum load (deltaL), and energy required for complete failure of the specimen (E) were measured. RESULTS: Fmax in the groups showed no significant differences. DeltaL values of groups A2, A3, and G3 were found to be significantly lower in comparison with the control group, whereas differences between the control group and other groups were not statistically significant. E values of A2 and A3 groups were significantly lower than that in the control group (P < .05), whereas the differences between the control group and other groups were not found to be statistically significant. No significant variations were determined between samples sterilized 1, 2, or 3 times in scanning electron microscopy micrographs, however, small irregularities were observed on autoclaved samples. CONCLUSIONS: Single use of polypropylene meshes is always recommended because of biocompatibility and infection risks. However, if re-use of the open packages is needed, ethylene oxide sterilization is preferred over autoclave sterilization. If ethylene oxide sterilization is not available then 1 cycle of resterilization with an autoclave can be used.

Oxygen plasma modification of polyurethane membranes.

Polyurethane membranes were prepared under nitrogen atmosphere by using various proportions of toluene diisocyanates (TDI) and polypropylene-ethylene glycol (P) with addition of no other ingredients such as catalysts, initiator or solvent in order to achieve medical purity. Effects of composition on mechanical properties were examined. In general, modulus and UTS values demonstrated an increase and PSBR demonstrated a decrease as the TDI/Polyol ratio of the polymer increased. Elastic modulus, ultimate tensile strength (UTS) and per cent strain before rupture (PSBR) values were found to be in the range of 1.4-5.4 MPa, 0.9-1.9 MPa, and 60.4-99.7%, respectively. Surfaces of the membranes were modified by oxygen plasma applying glow-discharge technique and the effect of applied plasma power (10 W or 100 W, 15 min) on surface hydrophilicity and on the attachment of Vero cells were studied. Water contact angle values of the plasma modified surfaces varied between 67 degrees and 46 degrees, demonstrating a decrease as the applied plasma power was increased. The unmodified material had 42-45 cells attached per cm(2). It was observed that as the applied power increased the number of attached cells first increased (60-70 cells/cm(2) at 10 W) and then decreased (27-40 cells/cm(2) at 100 W). These demonstrated that surface properties of polyurethanes can be modified by plasma-glow discharge technique to achieve the optimum levels of cell attachment.

Cytotoxicity evaluation of gelatin sponges prepared with different cross-linking agents.

Gelatin is a natural polymer used in pharmaceutical and medical applications, especially in the production of biocompatible and biodegradable wound dressings and drug delivery systems. Gelatin granules hydrate, swell and solubilize in water, and rapidly degrade in vivo. The durability of these materials could, however, be prolonged by cross-linking by aldehydes, carbodiimides, and aldose sugars, but the biocompatibility of collagenous biomaterials is profoundly influenced by the nature and extent of cross-linking. In this study, gelatin sponges were prepared by using various cross-linkers such as glutaraldehyde (GA), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDAC), and D-fructose. The effects of the type and the amount of cross-linker on thermal and mechanical properties, stability, and cytotoxicity were investigated. The mechanical analysis data showed that an increase in the amount of GA in the sponge structures caused a slight increase in the modulus of elasticity but had almost no effect on the tensile strength. Increase in the EDAC concentration produced a maximum in the modulus of elasticity and tensile strength values. The stability of the sponges and the time required for complete degradation in aqueous media increased in parallel with the cross-linker content. In vitro studies carried out with fibroblast cells demonstrated a higher cell viability for the samples cross-linked with low concentrations of GA than for those cross-linked with EDAC.