Biomedical subjects

J G Thacker

Publications and source records attributed to J G Thacker.

At least 19 recordsLinked to original sources

PubMed1992

Biomechanical performance of ophthalmic surgical needles.

The mechanical performance of ophthalmic surgical needles is studied. Standard biomechanical tests, devised to evaluate the performance of ophthalmic surgical needles, are presented. Four comparable groups of ophthalmic surgical needles were selected from two different manufacturers for these biomechanical studies. The results of this testing demonstrate that needle point geometry and needle composition are important determinants of needle performance. When comparable size needles were evaluated, the biomechanical performance of the recently introduced CS160-6 ophthalmic needle (Ethicon, Inc) was superior to the AU-5, CU-5, and SU-5 needles (Alcon, Inc). Whereas the development of these biomechanical tests has allowed the evaluation of these ophthalmic needles, these same tests can be used to assess the performance of other new ophthalmic surgical needles.

Alloys↗

PubMed1991

Mechanical performance of surgical needle holders.

A new quantitative measurement of surgical needle holder performance has been described that records the forces (clamping moment) applied by the needle holder jaws to curved surgical needles. This test has been used to determine the applied clamping forces of four different surgical needle holders made by one manufacturer. By relating the magnitude of the clamping moment of needle holder to the resistance to bending of curved surgical needles, we propose a new scientific basis for selecting surgical needle and needle holders for wound closure.

Elasticity↗

PubMed1991

A new compound-curved needle for microvascular surgery.

A new compound-curved needle has been designed and developed for microvascular surgery from a unique stainless steel alloy, American Society for Testing Materials 45500. This needle has two distinct radii of curvature and a short tapered point, followed by a curved distal section. Despite its geometry, it exhibits similar resistance to bending and breakage as a curved needle with a single radius of curvature manufactured from the same alloy. The design of this new needle enables plastic surgeons to pass it through vessel walls with greater accuracy to a controlled depth and length of bite than a curved needle with a single radius of curvature.

Humans↗

PubMed1991

Biochemical performance of tapercut cardiovascular needles.

Standardized reproducible tests have been developed to determine the biomechanical performance of cardiovascular needles. The parameters used to assess performance were: 1) sharpness, 2) resistance to bending, and 3) ductility. Four comparable groups of tapercut and taper point cardiovascular needles were selected from different manufacturers for these biochemical studies. The results of this testing demonstrated that needle geometry, needle composition, and the manufacturer were important determinants of needle performance. When comparable needles were evaluated, the biochemical performance of cardiovascular needles manufactured by Ethicon, Inc. (Somerville, NJ) were superior to needles produced by other manufacturers. The superior performance characteristics of the cardiovascular needles produced by Ethicon, Inc. were related to their unique stainless steel alloy, American Society for Testing Materials 45500, which has greater yield and tensile strengths than the alloy used by the other manufacturers. This stainless steel alloy was ideal for the production of tapercut needles, which combined some of the features of a reverse cutting edge needle and taper point needle. Its very short cutting edges allowed it to penetrate the membrane at considerably lower penetration forces than were encountered with comparable taper point needles. In addition, the investigation indicated that the trocar point cardiovascular needles produced a large triangular defect whose diameter was much larger than that of the needle body. For this reason, the use of the trochar point needle is not recommended in cardiovascular surgery.

Biomechanical Phenomena↗

PubMed1990

Some biomechanical considerations of polytetrafluoroethylene sutures.

The biomechanical performance of polytetrafluoroethylene (PTFE) sutures has been compared with that of polypropylene sutures, the standard to which other sutures used in vascular and cardiac surgery are compared. The PTFE is supple and has no plastic memory, while the polypropylene suture is stiff and retains its plastic memory. In addition, the rate of creep encountered in the PTFE suture was significantly less than that of the polypropylene suture. The knotting profiles for knot security for either a square, granny, or surgeon's knot for polypropylene sutures were three throws each. In contrast, knot security with either a square or granny PTFE knot was accomplished with seven throws; six throws were needed for a secure surgeon's knot. The breaking strength of the unknotted and knotted PTFE sutures was approximately one half as great as that for the unknotted and knotted polypropylene sutures. Knot construction significantly reduced the breaking strength of polypropylene sutures but did not alter the breaking strength of PTFE sutures. The percent elongation experienced by both sutures before breakage did not differ significantly. The elasticity, as measured by work recovery, for the polypropylene suture was greater than that for the PTFE suture. On the basis of its unique biomechanical performance characteristics, the PTFE suture should have an important place in vascular and cardiac surgery.

Physical Phenomena↗

PubMed1990

Scientific basis for selecting staple and tape skin closures.

Use of tape and skin staples has many important clinical applications for surgical wounds. During the past two decades, our research program has identified the optimal performance parameters of these wound closure devices. On the basis of their unique performance characteristics, specific staplers and tapes are recommended for wound closure. The scientific basis for selecting staples and tapes for wound closure is based on their influences on the biology of wound repair and infection.

Bandages↗

PubMed1990

Scientific basis for selecting surgical needles and needle holders for wound closure.

Standardized reproducible tests have been devised to determine surgical needle sharpness, resistance to bending, and ductility. Three comparable groups of reverse cutting edge needles were selected from different manufacturers for measurement of these needle performance parameters. This testing demonstrated that needle diameter, manufacturing process, needle material composition, cross-sectional design, and the manufacturer were all important determinants of surgical needle performance. In addition, the biomechanics of curved surgical needle bending has been related to the clamping moment of surgical needle holders. This relationship identifies the surgical needle holder that can be used with surgical needles without deformation. The results of these studies provide a scientific basis for the selection of surgical needles and needle holders for use in surgery.

Equipment Design↗

PubMed1990

Metallurgically bonded needle holder jaws. A technique to enhance needle holding security without sutural damage.

A new needle holder jaw face has been specifically designed and developed to increase needle holding security without sutural damage. Tungsten carbide particles have been metallurgically bonded into the stainless steel jaw to create a fine granular surface. This bonded jaw enhances needle holding security by limiting either twisting or rotation of the clamped needle. In addition, compression of the monofilament synthetic sutures by the bonded jaws does not reduce suture breaking strength.

Equipment Design↗

PubMed1989

Biomechanics of curved surgical needle bending.

Because needle bending resistance is such an important factor in the selection of surgical needles, a standard quantitative test of needle bending has been devised to study the biomechanics of deformation of needles from three different commercial manufacturers. The superior resistance to deformation of needles made by one manufacturer has been related to the specific alloy, ASTM 45500 stainless steel, employed in its production. The needles produced from ASTM stainless steel 45500 have stronger tensile and yield strengths than those of the other alloys, accounting for their greater resistance to bending.

Alloys↗

PubMed1989

New atraumatic rounded-edge surgical needle holder jaws.

A new atraumatic smooth needle holder jaw with rounded edges that does not damage synthetic monofilament sutures is described herein. These rounded edges were created by mechanical filing of the sharp edges of smooth needle jaws. Compression of the monofilament suture between the needle holder jaw with sharp edges reduces the suture breaking strength compared with that of control sutures. A quality control method has been devised to detect the potentially damaging sharp edges of smooth needle jaws that can be easily implemented by needle holder manufacturers.

Suture Techniques↗

PubMed1989

Surgical needle sharpness.

We developed a standard reproducible test to determine surgical needle sharpness. This parameter was measured by recording the maximum force required to push a curved surgical needle through a thin laminated synthetic membrane. Three comparable groups of reversed cutting-edge needles were selected from different manufacturers for needle penetration testing. The results of this testing demonstrated that the needle diameter, manufacturing process, and the manufacturer were all important determinants of needle sharpness. Needles with a smaller diameter were sharper than those with a larger diameter. In addition, electrohoned or hand-honed needles were sharper than those subjected to only machine grinding. When comparably sized needles were compared, Ethicon manufactured the sharpest needles, followed by Davis & Geck and Deknatel needles. Scanning electron microscopic photographs and elemental analysis of the surgical needles could be correlated with their sharpness. The sharper needles had long, narrow cutting edge geometries compared with the short wide geometries of duller needles. The sharpest needles were fabricated from an American Society for Testing and Materials (ASTM) 45500 stainless steel alloy that has stronger tensile and yield strengths than those of ASTM 42000 and 42020 alloys used in the creation of the other needles. This stronger alloy allows the manufacturer to produce a longer, narrower cutting point geometry with reduced danger of either bending or breakage during surgery compared with needles made from weaker alloys (ASTM 42000 and ASTM 42020), which accounts for the superior sharpness of the Ethicon surgical needles.

Alloys↗

PubMed1989

A new quantitative measurement for surgical needle ductility.

Because surgical needle ductility is such an important factor in the selection of surgical needles, a new curved needle ductility test instrument was devised to measure the ductility of needles from three commercial manufacturers. The superior ductility of needles made by one manufacturer was related to the specific alloy, stainless steel ASTM 45500, used in their production. The ASTM 45500 stainless steel has a significantly greater tensile and yield strength than the other stainless steel alloys, accounting for its superior ductility.

Humans↗

PubMed1989

Needle holder damage to surgical needles.

Clamping surgical needles between the jaws of needle holders with teeth markedly weaken the needles, making them prone to breakage. In contrast, clamping surgical needles between either smooth needle holder jaws or jaws embedded with tungsten carbide particles did not alter the ductility of surgical needles.

Alloys↗

PubMed1989

Tests of two new polyurethane foam wheelchair tires.

The performance characteristics of four 24-inch wheelchair tires are considered; one pneumatic and three airless. Specifically, two new airless polyurethane foam tires (circular and tapered cross-section) were compared to both a molded polyisoprene tire and a rubber pneumatic tire. Rolling resistance, coefficient of static friction, spring rate, tire roll-off, impact absorption, wear resistance, and resistance to compression set were the characteristics considered for the basis of comparison. Although the pneumatic tire is preferred by many wheelchair users, the two new polyurethane foam tires were found to offer a performance similar to the high-pressure pneumatic tire. In addition, the foam tires are less expensive and lighter in weight than the other tires tested.

Equipment Design↗

PubMed1988

Splayed handle surgical scissors.

Splayed handle surgical scissors have distinct advantages over conventional scissors that limit hand fatigability. The ringlet configuration of the splayed scissors conforms to the normal resting posture of the hand. In addition, surgeons can apply greater force to the splayed scissor ringlets than that which could be applied to the ringlets of conventional scissors.

Equipment Design↗

PubMed1988

Principles of emergency wound management.

Every traumatic wound treated in the emergency department is a result of a finite energy source that caused tissue disruption. The dynamics of this exchange of energy will determine the magnitude of injury. Disruption of the body covering leaves the once-sterile underlying integument exposed to contamination. The contaminants are derived from either the victim (endogenous) or the exogenous energy source. The presence of a contaminant such as bacteria makes the care of the wound an exercise in microbiology. Other contaminants, such as dirt, also may reside in the recesses of the wound. Emergency physicians must understand the consequences of tissue trauma. A study of the mechanism of injury will provide a reliable indication of damages. Whether the tissue injury will be limited to the initial wounding depends on the outcome of the interaction between the contaminants and the wound. In the event that the contaminants are very reactive, a relatively insignificant wound may become a catastrophe. This circumstance can be averted by the implementation of a well-devised plan based on the biology of wound healing and infection.

Anti-Bacterial Agents↗

PubMed1988

Automatic wire twister.

This automatic wire twister used in surgery consists of a 6-inch needle holder attached to a twisting mechanism. The major advantage of this device is that it twists wires significantly more rapidly than the conventional manual techniques. Testing has found that the ultimate force required to disrupt the wires twisted by either the automatic wire twister or manual techniques did not differ significantly and was directly related to the number of twists. The automatic wire twister reduces the time needed for wire twisting without altering the security of the twisted wire.

Bone Wires↗

PubMed1988

Surgical needle holder damage to sutures.

Needle holder jaws with teeth produce distinct structural changes in synthetic sutures that cause a marked reduction in the suture breaking strength. This damage to the suture may account for disruptions of vascular and fascial wound closures in which continuous closure techniques are employed.

Humans↗