Biomedical subjects

G T Rodeheaver

Publications and source records attributed to G T Rodeheaver.

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↗

PubMed1992

Early tissue reaction to textured breast implant surfaces.

Capsular contracture around breast implants with smooth surfaces continues to be an unpredictable complication. Some surgeons believe that silicone implants covered with porous polyurethane foam have a lowered potential to contract. These textured implants are not as biocompatible as silicone. Recently, silicone implants with textured surfaces have been introduced with the hope that the incidence of unacceptable implant contracture will be reduced. Using a rat implant model, the tissue reaction to textured implant surfaces was assessed. The implant surfaces evaluated were Silastic II, Siltex, MISTI, Biocell, Silastic MSI, and Même. Disks of each implant material were implanted under the dorsal skin of rats for a period of 28 days. Each implant with its surrounding tissue was excised, processed for histological analysis, and assessed for the tissue's response to the implant with particular emphasis on the formation of a continuous collagen capsule. The results indicated that the magnitude of surface texturing influenced the development of a complete capsule. Implant surfaces with a texture of less than 150 microns in height or depth (Silastic II, Siltex, and MISTI) resulted in the formation of complete capsules. An implant (Biocell) with irregular texturing (200-350 microns) produced an organized capsule over most of its surface with localized interruptions of the capsule at the sites of its deepest cavities. Implant surfaces with texturing that exceeded 350 microns in height or depth (Silastic MSI and Même) resulted in inhibition of the formation of a continuous capsule during this 28-day study.

Adipose Tissue↗

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↗

PubMed1989

The effect of new monofilament absorbable sutures on the healing of musculoaponeurotic incisions, gastrotomies, and colonic anastomoses.

The purpose of this study was to quantitate the effect of two new synthetic monofilament absorbable sutures, Maxon and PDS, on the healing of musculoaponeurotic incisions, gastrotomies, and colonic anastomoses. Wound healing was assessed by measuring the resistance of the closed wound to leak or burst with controlled infusion of fluid. Bursting strength measurements of these incisions were compared with those undertaken in age-weight matched controls without wounds to determine the rate of gain of wound strength. The bursting strength measurements of unwounded tissue was found to vary according to the age, weight, and specific tissue. As the animals gained weight over 42 days, the bursting strength of their colons and musculoaponeurotic tissues significantly increased. In general, the regain of prewounding bursting strength was inversely proportional to the bursting strength of the unwounded tissue. The bursting strength of abdominal musculoaponeurotic tissue was the highest, followed by the stomach and then the colon. The time intervals in which the wounded musculoaponeurotic tissues, gastrotomies, and colonic anastomoses regained the strength of the unwounded tissue was 42, 14, and 7 days, respectively. The performance of Maxon and PDS sutures in the musculoaponeurotic tissues, gastrotomies, and colonic anastomoses was similar.

Abdominal Muscles↗

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

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↗

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

Recurrent skin infections: a diagnostic enigma.

Our 25 years of experience with treating patients with recurrent skin infections has resulted in a rational plan that usually solves this diagnostic enigma. Our evaluation consists of a comprehensive examination of the infected tissue, as well as a search for systemic factors and diseases that interfere with host defenses and/or the biology of wound repair. Patient assessment begins with a detailed history, a search for foreign bodies in the wound, as well as histologic and microbiologic examinations of the infected tissue. Clinical recognition and laboratory evaluation for metabolic and endocrinologic dysfunction, a deficiency of the immune system, protein-calorie malnutrition, or a specific defect in collagen synthesis are other integral components of our diagnostic plan for patients with recurrent skin infections.

Antibody Formation↗

PubMed1988

Large disposable trephines for circular excision biopsy of the skin.

Large disposable circular trephines have been developed specially for circular excision biopsy of the skin. This technique is a simple and practical alternative to the traditional method of excision. It has the advantages of aligning the incision in the direction of the maximum skin tensions and reducing the length of the final wound closure.

Biopsy↗

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↗

PubMed1987

Mechanical performance of monofilament synthetic absorbable sutures.

The purpose of this study was to evaluate the mechanical performance of two new synthetic monofilament absorbable sutures. The polydioxanone sutures is prepared by polymerizing and extruding the monomer, paradioxanone, in the presence of a suitable catalyst. The other suture is a modified polyglycolic acid suture, made by reacting trimethylene carbonate and glycolide. The knot configuration (1 = 1 = 1, 1 x 1 x 1, and 2 = 1 = 1) required for knot security was identical for the two synthetic monofilament sutures. The mean knot breaking strengths for the polydioxanone and modified polyglycolic acid sutures did not differ significantly. The surfaces of these sutures exhibited a low coefficient of friction which was slightly increased by hydration. The most distinctive difference between the handling characteristics of these two sutures was their flexural rigidity. The stiffness of the polydioxanone suture was 60 percent greater than that of the modified polyglycolic acid suture.

Polydioxanone↗

PubMed1987

Considerations in the choice of sutures for wound closure of the genitourinary tract.

The ideal suture for use within the urinary tract should maintain its tensile strength until wound repair is satisfactory and then it should undergo rapid total absorption without promoting stone formation. The bladder has a great potential for repair, attaining 100 per cent of the strength of the unwounded tissue in 14 to 21 days. Braided synthetic absorbable sutures appear to be suited ideally for closure of incised wounds of a urinary conduit. They maintain their tensile strength for approximately 21 days, during which time the healing tissues regain strength rapidly. Because sutures are foreign bodies and have access to urine, they may serve as a nidus for stone formation. Several factors that have been identified as important determinants of foreign body urolithiasis include the presence of urine, urine volume and pH, infection, physical and chemical configuration of the foreign body, and animal species. The incidence of suture urolithiasis is related directly to the duration in which the sutures are present in the urinary tract. Consequently, absorbable sutures are preferred over nonabsorbable sutures for closure of wounds of the urinary conduit. In the absence of infection braided synthetic absorbable sutures have distinct advantages over gut sutures for closure of urinary tract wounds. They are absorbed by nonenzymatic hydrolysis in a predictable manner with limited inflammatory response. In contrast, gut sutures have an unpredictable absorption rate by enzymatic degradation and elicit an exaggerated inflammatory response. Because infected urine, especially Proteus species, accelerates the degradation of absorbable synthetic sutures to a greater degree than gut sutures, wound closure in the presence of infection should be accomplished with the absorbable natural fiber suture. Nonabsorbable sutures or staples should not be used in the urinary tract because they predictably promote urolithiasis.

Collagen↗

PubMed1987

A temporary nontoxic lubricant for a synthetic absorbable suture.

Synthetic absorbable sutures have been coated with lubricants to improve their handling characteristics. A unique surfactant, poloxamer 188, has been used to coat the surface of the polyglycolic acid sutures. This lubricant was chosen because it does not damage the tissues defenses of the host and invite infection. Since poloxamer 188 is readily soluble in aqueous solutions, it is rapidly absorbed in the tissue environment resulting in an uncoated suture that displays increased knot security. The coating of polyglactin 910 is also minimally reactive in tissues and does not damage tissue defense. In contrast with the coated polyglycolic acid sutures, the knot security of the coated polyglactin 910 sutures is not altered by exposure to an aqueous environment or implantation. The increased knot security of the coated polyglycolic acid suture after implantation is considered to be a distinct clinical advantage over that of the coated polyglactin 910 sutures.

Animals↗

PubMed1987

Unique performance characteristics of Novafil.

Polybutester is a unique copolymer that can be extruded as a flexible monofilament nonabsorbable suture. The mechanical performance of this new suture material was compared with that of polypropylene and nylon. The results indicate that polybutester sutures are as strong, have the same degree of total elongation at break and knot as the other monofilament sutures. In contrast with polypropylene and nylon sutures, the polybutester sutures have a perceptible stretch, are more elastic and flexible, and exhibit less creep. Polybutester sutures appear to be an acceptable alternative to polypropylene and nylon sutures and their unique mechanical properties may even prove to be superior in vivo.

Elasticity↗