Biomechanical performance of new cardiovascular needles.

Cardiovascular needles are now being manufactured from new stainless steel alloys containing high concentrations of nickel, Surgalloy and Ethalloy. The purpose of this study was to compare the biomechanical performance of a cardiovascular needle made of Surgalloy with a comparably sized needle made of Ethalloy. The parameters of biomechanical performance included sharpness, maintenance of sharpness, resistance to bending, and ductility. Because the biomechanical performance of these needles was remarkably similar, cardiovascular needles made of either the Surgalloy or Ethalloy alloys are recommended for cardiovascular surgery.

Wheelchair caster shimmy II: damping.

The theory of shimmy damping is investigated including tire friction, spindle bearing friction, and hydraulic damping. A new theoretical improvement in hydraulic damping is presented. Experimental results are presented along with a discussion concerning the limitations due to the approximations used in the theory. The basic theory of wheelchair caster shimmy was published by the authors in 1984, and an examination of the sources of shimmy damping is corrected and updated in this paper.

Biomechanical performance of powder-free examination gloves.

Biomechanical performance studies were undertaken for powder-free, latex and nitrile examination gloves. Using standardized tests, examination glove performance was judged by measuring glove thickness, glove puncture force, glove tape adhesion force, glove donning force, glove stiffness, and immediate unrecovered stretch. Even though the nitrile examination gloves were thinner than the latex examination gloves, they exhibited a greater puncture resistance. In addition, tape adherence to the N-Dex nitrile glove was the lowest. Moreover, measurements of the handling characteristics of the nitrile examination gloves demonstrated that they are an acceptable alternative to latex examination gloves. While these biomechanical studies demonstrate the superiority of the nitrile examination gloves, clinical glove evaluation is still needed to determine their performance in the health care setting.

Biomechanical performance of latex and non-latex double-glove systems.

The purpose of this study was to evaluate ten commercially available latex, powder-free surgical gloves and four commercially available non-latex, powder-free surgical gloves using standardized, reproducible biomechanical parameters that included glove thickness, puncture resistance, and glove donning force. For all gloves tested, with one exception (Neolontrade mark PF), puncture resistance increased for double-gloves as compared to single-gloves. In addition, single-glove thickness was not a reliable determinant of puncture resistance for either latex or non-latex gloves. For the latex gloves, the Ultrafree double and single-gloves exhibited the highest puncture resistance. The glove donning forces for the Biogeltrade mark M and Biogel Sensortrade mark single-gloves were the lowest. In contrast, the Biogel Revealtrade mark and Encoretrade mark Ultra-Thick exhibited the lowest double-glove donning forces. On the basis of these performance tests of latex gloves, the surgeon should consider the Biogel Reveal as well as the Ultrafree gloves for their latex double-glove system. For the non-latex gloves, the Pure Advantage Nitriletrade mark glove had the highest puncture resistance for one layer and two layers of glove material. The thin Pure Advantage Nitrile glove was the most resistant to glove puncture. The Pure Advantage Nitrile glove had low glove donning forces for both single-glove donning configurations and double-glove donning configurations. Consequently, we recommend the Pure Advantage Nitrile glove as the powder-free, non-latex, double-glove system.

Biomechanical performance of examination gloves.

The purpose of this study was to compare the biomechanical performance of new powder-free commercially available synthetic examination gloves to that of commercially available powder-free latex examination gloves. The synthetic gloves were significantly thinner than the latex gloves. Despite the decreased thickness, all three nitrile gloves, as well as the polyvinyl chloride glove, exhibited a greater resistance to glove puncture. The glove donning forces varied considerably among all gloves, and wet donning forces were greater than dry donning forces. Under dry conditions, the donning forces for the synthetic gloves were less than or equal to the forces for the latex gloves. Because of their increased puncture resistance and similar donning forces, synthetic gloves are a safe alternative to latex examination gloves.

Biomechanical performance of orthopedic gloves.

The purpose of this study was to compare the biomechanical performance of commercially available orthopedic gloves to that of a single surgical glove, as well as a double glove system. The orthopedic gloves were found to be thicker than the single surgical glove. This increased thickness of the orthopedic glove was associated with a greater resistance to glove puncture. The thickest orthopedic gloves also had reduced tactile sensitivity when compared to the single surgical glove. In addition, the glove donning forces and glove hydration rates varied considerably. These latter biomechanical performance parameters were not significantly related to glove thickness. The double glove systems tested in this study had similar performance characteristics in regard to many of the orthopedic gloves. The glove donning forces for the double glove systems were the lowest of the gloves tested. In addition, the double glove systems displayed the greatest resistance to glove hydration of the gloves tested. Their performance in the glove hydration tests and the force required to don the double glove systems were much more desirable than any of the orthopedic gloves. The results of this study indicate that the double glove systems may provide a desirable alternative to the use of the single orthopedic gloves.

Failure of glove hole detection device for synthetic gloves.

Holes in latex gloves can be reliably detected by commercially available electronic devices. The purpose of this study was to compare the performance of an electronic glove hole detection device using latex gloves to that of neoprene, vinyl, and nitrile latex-free gloves. The electronic hole detection device accurately detected holes in the latex gloves during the 2-h study. In contrast, the latex-free gloves were immediately conductive of electricity in the absence of holes. Consequently, electronic glove hole detection devices cannot be reliably used with latex-free gloves.

Ease of donning commercially available latex examination gloves.

There are a wide variety of latex examination gloves now available for use by health care providers. A prospective randomized trial was completed to quantify the forces required to don a sample of seven cornstarch-lubricated gloves and 13 powder-free latex examination gloves. The data collected was analyzed by a 20 x 2 general factorial ANOVA, as well as two 1-way ANOVAs using a least significance difference post hoc test. Some powder-free gloves can be easily donned with dry or wet hands without tearing with forces comparable to those encountered with powdered gloves. With the advent of these powder-free examination gloves, powdered gloves can now be abandoned, protecting health professionals and patients from the dangers of absorbable dusting powders. Despite the dangers of the absorbable dusting powders and the Food and Drug Administration's requirement for labeling examination glove boxes, some manufacturers of powdered examination gloves do not appropriately label their boxes with a warning to the health professional and patient of the presence of powder.

Inadequate standard for glove puncture resistance: allows production of gloves with limited puncture resistance.

The National Fire Protection Association has developed standards for glove puncture resistance using a metal puncture probe. Biomechanical performance studies have demonstrated that glove puncture resistance to the probe is significantly greater than that of the hypodermic needle, suggesting that these standards have no clinical relevance. These standards give a false sense of security to health care personnel and sanction the production and use of gloves that give inadequate protection. The result is potentially harmful for medical personnel.

Influence of irrigation solutions on oscillating bone saw blade performance.

The influence of irrigation on bone cutting was determined by measuring the biomechanical performance of a bone cutting saw during irrigation with various solutions. Solutions of 0.9% saline and 10, 20, and 30% poloxamer-188 were used as the irrigant. A 10% solution of poloxamer-188 was judged to be the superior irrigant because it successfully maintained bone temperature at a controlled level without interfering with the rate of bone removal.

Biomechanical performance of cutting edge surgical needles.

The purpose of this study was to compare the biomechanical performance of cutting edge needles made of S45500 stainless steel alloy to Surgalloy stainless steel. The new high-nickel stainless steel alloy, Surgalloy, has superior performance characteristics over that of the other high-nickel stainless steel alloy, S45500. The Surgalloy needle is produced from a stronger stainless steel alloy than the S45500 needle. The Surgalloy needle has considerably greater resistance to bending than the needle produced from S45500 alloy. In addition, Surgalloy stainless steel has almost a twofold greater resistance to fracture than the S45500 stainless steel alloy.

A new computerized control unit for small bone surgical instruments.

The SmartDrive console represents an important advance in small bone surgery because it monitors and coordinates the operation of its handpieces. The SmartDrive console has the following unique features: 1) a handpiece recognition system; 2) an instrument speed display; 3) a handpiece display and monitoring system; 4) a torque instrument control system; 5) a temperature monitoring system; 6) and an irrigation system. Mechanical performance studies have been undertaken that have validated the accuracy of the monitoring systems of the consoles. The consoles provided reliable recordings of the rotational speeds of their hi-speed drills. The MicroAire console automatically shuts off its power as the temperature increased to 110 degrees F (43 degrees C). In contrast, the Stryker Command 2 console has a limited monitoring system that can not alter the operation of the handpieces.

A technique for quantifying the performance of oscillating bone saw blades.

A new model has been developed to evaluate the performance of oscillating surgical saw blades used in medical-implant procedures. A test apparatus was constructed to maintain a constant cutting force between a blade driven by a pneumatic powered oscillating saw and the bone. Evaluations of saw-blade performance were determined using the following outcome measures: cutting time, volume of bone removal, and peak cutting temperature. Two popular, commercially available blades similar in size and tooth geometry were evaluated. This model identified differences in the performance of these two types of oscillating saw blades.

Durability of oscillating bone saw blades.

The purpose of this study was to measure the durability of disposable saw blades using a standard bone-cutting experimental model that can be replicated in any laboratory. Using a constant cutting force, the bone-cutting efficiency was determined by recording the maximum cutting temperature and the rate of material removal. In this experimental study, porcine femurs as well as a synthetic bone substitute were used as the test samples for measuring cutting efficiency. Repeated cutting of these test materials did not significantly alter the performance of the disposable bone-cutting blades.

Innovations in oscillating bone saw blades.

The purpose of this study was to identify some of the determinants of saw-blade design that influence bone-cutting performance. Using a reproducible experimental model, saw-blade performance was judged by measuring the blade temperature and the rate of bone removal. The results of this study demonstrated that the rake angle and blade swing radius had significant influence on saw-blade performance.

Another cause of surgical needle holder damage to surgical sutures.

The sharp edges of the box lock of the needle holder can inadvertently damage the suture during instrument ties. Compression of a monofilament nylon suture between the sharp edges of the box lock of a surgical needle holder damages the suture, reducing its breaking strength. This adverse effect has been eliminated by one manufacturer whose needle holder box lock has rounded edges and sufficient space to permit passage of the suture.

Knot performance of polypropylene sutures.

A mechanical performance test using an Instron Tensile Tester demonstrated the superior handling characteristics of Surgipro suture as compared to Prolene suture that facilitated knot construction without suture breakage. For both granny and square knots, the knot run down forces for the Surgipro sutures were significantly less than those encountered for comparable knots for Prolene sutures. This propensity of the two-throw knots of Surgipro sutures to advance without breakage considerably facilitated knot construction.

Studies of determinants of glove hole puncture during electrosurgery.

Holes in surgical gloves are considered to be an important source of transmission of pathogens between patient and surgeon. The purpose of this study was to determine if electrosurgery could alter the integrity of latex surgical gloves. The effects of electrosurgery on 11 brands of commercially available latex surgical gloves were tested through an in vitro study that simulated the conditions in the operating room. Glove hole puncture was encountered only with coagulation current operating at the highest setting. In addition, maximal surface area contact with the hemostat to the glove surface was required to produce glove puncture. The presence of powder and glove hydration were not significant determinants of glove hole puncture. On the basis of our study, we believe that all surgical gloves tested offered the surgeon adequate protection at commonly used levels of cutting and coagulation current, as long as no breach existed prior to the donning of gloves.

Ease of donning commercially available powder-free surgical gloves.

There are a wide variety of powder-free gloves that can now be used by surgeons. The purpose of this study was to quantify the forces required to don these powder-free surgical gloves. The lowest donning forces for wet hands was encountered with powder-free gloves coated with a hydrogel polymer. In addition, the hydrogel coated gloves exhibited the least increase in donning forces from dry hands to wet hands. While greater forces were encountered with the other commercially available powder-free gloves than the hydrogel coated gloves, they all could be safely donned on dry hands without tearing.

Needle puncture resistance of surgical gloves, finger guards, and glove liners.

New puncture resistant materials are being developed for health professional use as protection against disease and needle stick injuries. The needle puncture resistance of protective gloves and glove liners from DePuy DuPont Orthopaedics and of finger guards from Zimmer was evaluated using a computerized needle penetration system to determine maximal penetration forces and the penetration work required for taper point and for cutting edge needles to penetrate these membranes. The Medak portion of the Life Liner glove liner and the Spectra portion of the FingGuard finger guard offered remarkable resistance against needle penetration as compared to the other glove liners and gloves tested. The cutting edge needles required considerably less penetration force and work to penetrate the FingGuard and Life Liner than that required with comparable size taper point needles. Because these unique protective materials had a limited distribution over the hand, the surgeon's hand remained susceptible to inadvertent needle puncture. While this protection against needle penetration in the Life Liner and the FingGuard represents an exciting advance in surgery, it is important to emphasize that this development is only one consideration in the selection of surgical gloves.