Comparison of 10-0 polypropylene and 10-0 nylon sutures in rat arterial anastomosis

The selection of suture materials is an important factor in further improving the results of microsurgical operations. In this study, two kinds of nonabsorbable suture materials, 10-0 polypropylene and 10-0 nylon monofilament, were compared in end-to-end anastomosis of 66 femoral arteries of adult rats. Both suture types were of identical size (70 microns needle/28 microns suture) and each artery received eight sutures. The vessels were harvested at various intervals from 2 hr to 180 days postoperatively and were evaluated by pathology, radiology, and tensile strength test. The results show that both sutures are capable of achieving excellent long-term patency (100%) of anastomosed sites. Polypropylene suture was equivalent to nylon in mechanical integrity of the anastomosis sites but was superior in handling, knotting, and biocompatibility. These physical and biological properties of polypropylene sutures may offer the benefits of diminished early and late complications at anastomosis sites and reduced operation time. Enhancement of contrast against surrounding tissue may make polypropylene a superior alternative to nylon sutures for microsurgical use.     

Load to failure of common meniscal repair techniques: effects of suture technique and suture material

Success of meniscal repair with early or immediate motion depends on the ability of the suture fixation to withstand the loads applied. Vertical and horizontal mattress suture techniques were tested using 2-0 Ethibond, and 0-PDS and 1-PDS sutures (Ethicon, Somerville, NJ). Mulberry knot technique was tested with 0-PDS and 1-PDS sutures. Twenty menisci (60 sutures) were tested for each suture material. Sutures were placed 3 to 4 mm from the peripheral edge of the meniscus with double barreled cannulas for vertical and horizontal mattress techniques or a spinal needle for the mulberry knot technique, reproducing clinical techniques of meniscal repair. Mechanical testing of suture fixation was performed to failure at a rate of 10 mm/min on a MTS material testing system (MTS Systems Corp, Minneapolis, MN). Suture pullouts were reported as the load displacement to failure from the inner fragment only, because clinical failure would ensue should a suture pull through the inner fragment of a tear. Vertical mattress technique with 1-PDS suture had significantly greater load to failure than any other combination (P < .05). Analysis of variance showed that the vertical mattress technique had statistically superior pullout strength (P < .0001) compared with the horizontal mattress and mulberry knot techniques, which were statistically similar. There were significant differences (P < .0001) between suture types, with 1-PDS proving best compared with 0-PDS, which was stronger than 2-0 Ethibond. Selection of suture material had the greatest impact on vertical mattress load to failure and was not important to the strength of the other techniques.     

An evaluation of 8-0 Polyglactin 910 synthetic absorbable suture in cataract surgery

This study describes the operative and postoperative performance of 8-0 Polyglactin 910 in cataract surgery. The evaluation represents a clinical comparison of 7-0 Polyglactin 910 to the same suture in 8-0 size in 155 cataract surgical procedures. In 45 cases, 8-0 Polyglactin 910 was the sole wound closure material used. 8-0 Polyglactin 910 provided high tensile strength, good knot security, batch-to-batch uniformity, ease of handling, minimal reaction, and a predictable absorption rate that was virtually completed in 33 days. When compared to 7-0 Polyglactin 910, 8-0 produced less tissue drag, fibrillation, and reaction. Early in our series, three cases of wound dehiscence occurred. One was caused by trauma and the other two by 8-0 Polyglactin 910 cutting through tissue. This study's conclusion stresses avoiding the tendency of tying the knot too tightly to prevent suture pull-out.     

Polyvinylidene fluoride monofilament sutures: can they be used safely for long-term anastomoses in the thoracic aorta?

Polyvinylidene fluoride (PVDF) represents an attractive alternative to polypropylene as a monofilament vascular suture because of its satisfactory physicochemical properties, it ease of handling, and its good biocompatibility. However, the polymer's ability to remain mechanically and chemically stable when exposed to a mild hydrolytic environment over the long term has yet to be demonstrated. One in vitro study involved the comparison of the long-term relative resistance of PVDF and polypropylene sutures to hydrolysis for a period of 9 years. The PVDF suture showed major molecular rearrangements from the original ratio of three crystalline structures to the single beta crystalline phase. The observation of some surface oxidation and water inhibition did not significantly modify the tensile strength of the PVDF suture, which retained 92.5% of its original value. In contrast, the polypropylene sample did not undergo any recrystallization but was associated with more oxidation byproducts and more water molecules near the surface, which contributed to a 46.6% loss in initial tensile strength. An in vivo study confirmed that PVDF sutures are biocompatible and are able to maintain satisfactory biostability when used to anastomose thoracic aortic allografts for a period of 6 months in the dog. The cellular reaction of fresh allografts as well as the control autografts to PVDF sutures was minimal. In other allografts that had been preserved in a supplemented medium for 1 week prior to implantation, the PVDF sutures healed satisfactorily with the formation of neocollagen and few macrophages surrounding the monofilament. No evidence of instability at the allograft-host artery junction was observed, confirming that the PVDF sutures were able to ensure a secure anastomosis in the thoracic aorta. PVDF sutures have demonstrated superior long-term biostability in vitro and minimal tissue response in vivo. These are two essential requirements when evaluating the use of a suture for vascular surgery in general and thoracic aortic surgery in particular.     

Why make monofilament sutures out of polyvinylidene fluoride?

In recent years some clinical reports have associated suture failures with polypropylene monofilaments. Therefore there is interest in developing an alternative suture material that is less thrombogenic than polyester and similar in handling characteristics but less prone to mechanical failure than polypropylene. To this end, Peters Laboratoire Pharmaceutique has developed a new monofilament suture material from polyvinylidene fluoride (PVDF), which has been subjected to a special treatment to modify its crystalline form and level of crystallinity. The purpose of this study was to evaluate its mechanical, chemical, and biologic properties and to compare its performance, in a peripheral vascular application, to that of a polypropylene control. A series of in vitro tests were performed to study the morphology, tensile properties, creep, surface chemistry, thermal characteristics, and resistance to iatrogenic trauma. In addition, an in vivo trial was undertaken in which vascular prostheses anastomosed with either PVDF or polypropylene sutures were implanted as a thoracoabdominal bypass for 6 months in the dog. Histologic and degradation analyses were performed on the explants. The results from the mechanical tests on 4-0, 5-0, and 6-0 PVDF and polypropylene sutures demonstrated that although both materials have similar breaking strengths, the PVDF has a higher extension at break, has less delayed extension when under tensile creep testing, and suffers less trauma than the polypropylene when compressed by a standard needle holder. While chemical analyses found evidence of surface oxidation on both types of sutures, thermal analysis confirmed that the level of crystallinity of the PVDF polymer is higher than that of the polypropylene control. During the pilot study in animals, PVDF sutures were found to have good handling and frictional characteristics that facilitated the tying of knots. Histologic analysis of the explants found no inflammatory cells in the tissue surrounding either the PVDF or polypropylene sutures, and scanning electron microscopic examination of the cleaned suture surfaces found no evidence of degradation during 6 months in vivo. Though preliminary in nature, these findings indicate that monofilament sutures made from PVDF provide an attractive alternative to those made from polypropylene for use in cardiovascular surgery. In addition to providing acceptable in vivo behavior and being easy to manipulate and more resistant to iatrogenic injury, PVDF materials can be sterilized by beta or gamma radiation and so can reduce dependence upon ethylene oxide and chlorofluorohydrocarbons.     

Changes in knot-holding capacity of sliding knots in vivo and tissue reaction

OBJECTIVES: To evaluate and compare the in vivo strength, knot efficiency, and knot security of 4 types of sliding knots, and to assess tissue reaction to study the effect of knot configuration, knot volume, and suture size. DESIGN: Randomized trial. SETTING: Experimental Medical Research Institute, Istanbul, Turkey. SUBJECTS: Wistar rats. INTERVENTION: To assess the tissue reaction, a midline laparotomy incision was made in 112 rats and sutured with various interrupted knots in silk and nylon sutures of 2/0 and 4/0 (United States Pharmacopeia) sizes. Suture loops were implanted in subcutaneous pouches in the rat abdomen. Sutures were all extracted at days 4, 7, 11, and 20 to determine their knot-holding capacity. MAIN OUTCOME MEASURES: Knot efficiency and percentage decrease in knot-holding capacity were examined. Knot, tissue reaction, and inflammatory sheath volumes were measured. RESULTS: The 4/0 knots lost more strength than the 2/0 knots. The alternating knots with different patterns were more efficient and secure than the simple alternating ones. The alternating parallel knot was found to be unreliable. The tissue response to all the knots, except 2/0 nylon, was similar. The inflammatory sheath volume varied depending on the knot volume, suture size, and knot configuration. CONCLUSION: The use of alternating sliding knots with different patterns is recommended to replace simple alternating sliding knots.     

Synthesis of lactosyl phosphate diester derivatives of nucleosides

It has been postulated that some arthroscopic shoulder stabilization failures may be due to knot slippage. In an effort to improve arthroscopic technique, we performed tensile testing on four arthroscopically tied knots with two commonly used suture materials. Handtied square knots served as controls. Sutures of No. 1 Maxon and No. 1 Ticron were used. Four types of sliding knot configurations were tested: the overhand loop, the Duncan loop, the Roeder knot, and the Snyder knot. Knots were tied via a knot pusher, and testing was performed in a normal saline-filled thermoplastic chamber. Knots were tied around two rings connected to a Bionix 858 materials testing apparatus. The knots were tested under conditions of cyclic loading and loading to failure. Results of the testing revealed that the most important factor in knot security was the type of suture material, although there were differences with the type of knot. With the Maxon suture, there was significantly decreased ultimate failure load of all of the arthroscopically tied knots compared with handtied square knots. Knots tied with Ticron were similar in strength for both arthroscopically and handtied groups. The surgeon who chooses a monofilament absorbable suture should be aware that a high percentage of knots fail under low load cyclic testing, and that all of these knots were inferior to handtied square knot controls in testing to failure.     

Effect of shigella enterotoxin 1 (ShET1) on rabbit intestine in vitro and in vivo

The purpose of this study was to identify the optimal knot construction for interrupted dermal sutures. A synthetic braided absorbable suture, sizes 3-0 and 5-0, was selected for this evaluation. With reproducible mechanical performance tests, we determined that the construction of secure knots without ears required one additional throw as compared with secure knots with 3-mm ears. The direction of applied tension did not alter knot security, with the exception of granny knots, which required an extra throw when tension was applied parallel to the suture loop. Because interrupted dermal knot construction is accomplished without knot ears and with an applied tension parallel to the wound, one additional throw must be added to the knot to ensure knot security.     

Tissue fixation security in transosseous rotator cuff repairs: a mechanical comparison of simple versus mattress sutures

The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.     

A DNA controlled-release coating for gene transfer: transfection in skeletal and cardiac muscle

In this paper we report a novel technique of DNA-polymer coating for gene transfer. A proprietary DNA polymer solution was used for thin-layer coating on a chromic gut suture as a model study. The coated sutures were characterized for physical properties such as coating thickness, mass of the DNA deposited on the suture, surface characteristics as determined by scanning electron microscopy, and in vitro DNA release characteristics under simulated physiologic conditions. The in vivo gene transfection using DNA-coated sutures was demonstrated in rat skeletal muscle and in canine atrial myocardium. A heat-stable human placental alkaline phosphatase (AP) plasmid was used as a marker gene. Incisions of 1 to 1.5 cm were made in the rat skeletal muscles or the canine atrial myocardium. The sites were closed with either the DNA-coated sutures or control sutures. Two weeks after the surgery, the tissue samples adjacent to the suture lines were retrieved and analyzed for AP activity. The DNA-coated sutures demonstrated a sustained release of the DNA under in vitro conditions, with an approximately 84% cumulative DNA release occurring in 26 days. An agarose gel electrophoresis of the DNA samples released from the suture demonstrated two bands, with the lower band corresponding to the input DNA (supercoiled). It seems that there was a partial transformation of the DNA from a supercoiled to an open circular form due to the polymer coating. The tissue sites, which received the DNA-coated sutures, demonstrated a significantly higher AP activity compared with the tissue sites that received control sutures. In the rat studies, the mean AP activity (square root of cpm/microgram protein) was 43.6 +/- 3.3 vs 20.6 +/- 2.1 (p = 0.001) at the control sites. Similarly, in the canine studies, the AP activity was 73.6 +/- 7.4 Vs 21.6 +/- 1.4 (p = 0.0009) at the control sites. Thus, our studies demonstrated a successful gene transfer using our DNA-polymer coating technique. This technique could be useful for coating sutures used in vascular and general surgery, and also for coating medical devices, such as stents, catheters, or orthopedic devices, to achieve a site-specific gene delivery.     

Thermo-oxidative ageing behavior of cerium oxide/silicone rubber

Cerium oxide/silicon rubber was prepared via mechanical blending.Mechanical and frictional properties,as well as thermal stability after thermo-oxidative ageing were investigated in this rubber composite.3D surface profilometry,scanning electron microscopy(SEM) and thermogravimetry analysis(TGA) were used to study the friction surface characteristics,friction mechanism and thermal stability,respectively.Additionally,swelling experiments were carried out to investigate the variation of crosslinking density.After thermo-oxidative ageing,the tear strength of cerium oxide/silicon rubber decreases.However,in the early ageing stage,improvements in tensile strength,elongation at break,and frictional performance are caused by crosslinking density increments.Moreover,the addition of cerium oxide remarkably improves the re-cross linking degree during ageing process,which in turn decreases the number of holes on the friction surface and endows the silicon rubber with better mechanical and frictional properties,as well as thermo-oxidative ageing resistance.     

Comparative study of biological glues: cryoprecipitate glue, two-component fibrin sealant, and "French" glue

BACKGROUND: Although biological glues have been used clinically in cardiovascular operations, there are no comprehensive comparative studies to help clinicians select one glue over another. In this study we determined the efficacy in controlling suture line and surface bleeding and the biophysical properties of cryoprecipitate glue, two-component fibrin sealant, and "French" glue containing gelatin-resorcinol-formaldehyde-glutaraldehyde (GRFG). METHODS: Twenty-four dogs underwent a standardized atriotomy and aortotomy; the incisions were closed with interrupted 3-0 polypropylene sutures placed 3 mm apart. All dogs had a 3- by 3-cm area of the anterior wall of the right ventricle abraded until bleeding occurred. The animals were randomly allocated into four groups: in group 1 (n = 6) bleeding from the suture lines and from the epicardium was treated with cryoprecipitate glue; in group 2 (n = 6) bleeding was treated with two-component fibrin sealant; group 3 (n = 6) was treated with GRFG glue; group 4 (n = 6) was the untreated control group. The glues were also evaluated with regard to histomorphology, tensile strength, and virology. RESULTS: The cryoprecipitate glue and the two-component fibrin sealant glue were equally effective in controlling bleeding from the aortic and atrial suture lines. Although the GRFG glue slowed bleeding significantly at both sites compared to baseline, it did not provide total control. The control group required additional sutures to control bleeding. The cryoprecipitate glue and the two-component fibrin sealant provided a satisfactory clot in 3 to 4 seconds on the epicardium, whereas the GRFG glue generated a poor clot. There were minimal adhesions in the subpericardial space in the cryoprecipitate and the two-component fibrin sealant groups, whereas moderate-to-dense adhesions were present in the GRFG glue group at 6 weeks. The two-component fibrin sealant was completely reabsorbed by 10 days, but cryoprecipitate and GRFG glues were still present. On histologic examination, both fibrin glues exhibited minimal tissue reaction; in contrast, extensive fibroblastic proliferation was caused by the GRFG glue. The two-component and GRFG glues had outstanding adhesive property; in contrast, the cryoprecipitate glue did not show any adhesive power. The GRFG glue had a significantly greater tensile strength than the two-component fibrin sealant. Random samples from both cryoprecipitate and the two-component fibrin glue were free of hepatitis and retrovirus. CONCLUSIONS: The GRFG glue should be used as a tissue reinforcer; the two-component fibrin sealer is preferable when hemostatic action must be accompanied with mechanical barrier; and finally, the cryoprecipitate glue can be used when hemostatic action is the only requirement.     

Serum dopamine-beta-hydroxylase activity in rat during post-natal development

The strength of knotted thread for 12 different types of suture knot in combination with 11 types of suture material used in surgery was investigated one week after insertion in subcutaneous tissue in rabbits. The results were compared with similar investigations on knot strength carried out with 'dry knots'. The thread dimension used in both experiments was 000 (USP). As in vitro, the weakest point of a suture loop subjected to traction was the knot. The incidence of thread rupture within the loop but outside the knot was 1.4% in vitro and 5.9% in vivo, and was commonest with plain catgut. With one exception, however, thread breakage occurred at greater strain than the average required to produce knot failure with the material in question. A greater proportion of knots slipped in vivo then in vitro (72% and 35% respectively), with reduction of the strength of the suture loop as result. There was also greater scatter of measured values under in vivo conditions (standard deviation: 11% in vitro, 23% in vivo). For 7 of 11 suture materials the results indicated a reduction in knot-holding power after one week in situ in the living animal compared with in vivo conditions. This was naturally enough most marked with the two types of catgut (chrome 48%, plain 57%). In contrast, Dexon apparently remained unchanged after one week in vivo. The non-absorbable materials tested showed an estimated average fall in knot-holding power from 100% to 88% (range 109-65%), viz, an average of 12% units. The loss of holding power in vivo was, however, apparently never greater than 1/3 compared with 'dry knots' and calculated on average for all types of knot with non-absorbable materials.     

The effects of multiple-strand suture techniques on the tensile properties of repair of the flexor digitorum profundus tendon to bone

We examined the effects of multiple-strand suture techniques on the tensile properties of flexor digitorum profundus tendon-to-bone repairs in a human cadaver finger model. Forty-four fingers were obtained from the cadavera of fifteen donors who had been an average of seventy-four years old (range, fifty-four to eighty-nine years old) at the time of death. Four or eight-strand proximal grasping sutures were secured to the distal phalanx of each finger with use of either a suture anchor or a dorsally placed button. There were four subgroups of eleven fingers each. We found that repairs performed with use of a dorsally placed button had greater yield force, ultimate force, and rigidity than those performed with use of an anchor and that repairs performed with eight strands had greater ultimate force than those performed with four strands. These differences were significant (p < 0.05). We could detect no differences among the four types of repairs with regard to the amount of relative tendon-bone elongation at twenty newtons of force. The repairs performed with eight strands and a dorsally placed button had an average yield force (and 95 per cent confidence interval) of 50.0 +/- 14.1 newtons, an average ultimate force of 68.5 +/- 14.6 newtons, an average rigidity of 744 +/- 327 newton/(millimeter/millimeter), and an average tendon-bone elongation of 3.4 +/- 0.7 millimeters at twenty newtons of force. Multiple-comparison testing showed that the eight-strand repairs performed with a dorsally placed button had greater ultimate force than the other three types of repairs as well as greater yield force and rigidity than the four and eight-strand repairs performed with a suture anchor.     

烧结温度对Fe-Cu-Mo-C合金组织和性能的影响

采用机械球磨混粉和真空烧结相结合的方法制备了Fe-Cu-Mo-C合金,研究了不同烧结温度对粉末冶金Fe-Cu-Mo-C合金材料的显微组织、密度、抗拉强度和摩擦磨损性能的影响。结果表明:随着烧结温度由1 000℃升高到1 100℃,Fe-Cu-Mo-C合金烧结体组织孔隙数量减少、孔隙尺寸明显降低;当烧结温度提高到1 150℃时,烧结体组织中孔隙尺寸增大。随着烧结温度升高,烧结体的密度、硬度、抗拉强度和伸长率先增大后减小,磨损量先降低后升高。最佳烧结温度为1 100℃,此时烧结体的密度为6.90 g/cm3,抗拉强度为319 MPa,洛氏硬度为34.7 HRC,磨损量为0.087 g。     

Seminoma with isolated central nervous system relapse, and salvage with craniospinal irradiation

Komanduri et al showed that dorsal tendon repairs using Kessler and Bunnell techniques were stronger than the standard volar repair (J Hand Surg 1996;21 A:605-611). They concluded that when testing in the anatomic curvilinear mode, the differences in strength were due to tension banding. Soejima et al challenged that concept by stating that the difference in strength was in the biomechanics of the dorsal tendon itself (J Hand Surg 1995;20A:801-807). We set out to confirm Soejima et al's theory by using more core suture techniques. We compared the tensile strength at 2-mm gap and the ultimate tensile strength of Kessler, Strickland, Robertson, and modified Becker sutures. Ten repairs of each suture type were placed either dorsally or volarly in matched human cadaver flexor tendons. There was no statistical difference between volar and dorsal placement for either maximum tensile force or force at 2-mm gap. Our study does not confirm Soejima et al's in any of the four suturing techniques.     

Zr含量及固溶温度对Cu-Zn-Al形状记忆合金性能的影响

通过金相观察、形状回复率测试和拉伸试验,研究Zr含量及固溶温度对Cu-Zn-Al形状记忆合金性能的影响。结果表明:在一定范围内,增加Zr含量,可以细化晶粒,提高铜基记忆合金的记忆性能、抗拉强度和延伸率,改善合金冷加工性能;固溶温度对铜基形状记忆合金影响很大,在810℃时,金相呈现典型的板条状马氏体,形状回复率能达到90%以上,抗拉强度和延伸率也较高。     

热轧Φ6 ~40 mm HRB500E螺纹钢筋的生产实践

根据GB/T 1499.2-2018标准,水钢设计了Φ36～40 mm HRB500E螺纹钢筋的内控成分为（%）0.22～0.25C、0.60～0.70Si、1. 50～1.60Mn、0.11～0.13V、P≤0. 045、S≤0. 045。采用"100 t顶底复吹转炉冶炼-挡渣出钢-脱氧合金化-LF炉精炼-160方坯连铸-方坯加热-棒材轧制-空冷"的工艺流程,生产出的Φ36 mm HRB500E螺纹钢筋的屈服强度Re_L⁰ 540～580 MPa,抗拉强度R_m⁰ 705～735 MPa,断后伸长率A 15. 5%～20. 5%,最大力总延伸率A_gt 11.5%～14.0%,实测抗拉强度与实测屈服强度之比R_m⁰/R_eL⁰为1.25～1.32,实测屈服强度与GB/T 1499.2-2018标准要求的最低屈服强度之比R_eL⁰/R_eL为1.08～1.16,因此,钢筋的力学性能满足GB/T 1499.2-2018标准要求。生产出的Φ40 mm HRB500E钢筋的微观组织为铁素体+珠光体,晶粒度为9.5～10级。     

平整和自然时效对超低碳烘烤硬化钢板性能的影响

研究了平整率(0～3.3%)和自然时效对830℃退火0.7 mm超低碳烘烤硬化钢板(%:0.003 0C、0.008Nb-0.003 Ti、0.003 0N和0.0030C、0.012Nb-0.012Ti、0.004 2N)力学性能和烘烤硬化性能的影响。结果表明,最初随平整率增加,由于柯氏气团减少和位错密度增加,屈服强度降低;当0.008Nb-0.003 Ti钢平整率达到0.48%,0.012Nb-0.012Ti钢平整率达到0.26%时,屈服强度降至最低;平整率继续增加由于冷加工硬化增强,钢的屈服强度升高。平整率过低和过高,均会导致烘烤硬化性能下降。平整率控制在0.5%～1.5%时,钢板能获得较低的屈服强度、较高的断后伸长率和最大的烘烤硬化性能。钢板经自然时效3个月,烘烤硬化性能和延伸率下降。     

Manual vs robotically assisted laparoscopic surgery in the performance of basic manipulation and suturing tasks

OBJECTIVE: To compare the surgical performance of manual and robotically assisted laparoscopic instruments on basic maneuvers and intracorporeal suturing in inanimate models. DESIGN: A set of laparoscopic tasks was used to evaluate basic endoscopic movements and intracorporeal suturing: positioning a cylinder on a Peg-Board, dropping beads into receptacles, running a 25-cm rope, and capping a hypodermic needle. Intracorporeal knot tying and running a suture through predetermined points were evaluated separately. The sutures used for these tasks were 2-0 and 4-0 silk and 6-0 and 7-0 polypropylene. PARTICIPANTS: Twenty surgeons completed the set of laparoscopic tasks manually and then with a robotically assisted system. None had used the robotic system before. MAIN OUTCOME MEASURES: Time required to complete the tasks and the precision in performing them. RESULTS: The robotic system accurately reproduced the movements of the surgeons and filtered their hand tremors efficiently. In the basic tasks, operative times were significantly longer for the robotic system (P<.001). In the suturing tasks, operative times were longer with the use of the robotic system for sutures sizes 2-0 and 4-0 (P<.001). However, time differences were not significant for suture sizes 6-0 and 7-0 (P> or =.07). Precision measurements were similar for all tasks using the manual instruments and the robotically assisted system. No significant differences were found between the performance of advanced laparoscopic surgeons and laparoscopic fellows. CONCLUSIONS: Laparoscopic maneuvering and suturing is faster and just as precise when performed manually as when performed with the prototype robotic system. These differences in speed are inversely proportional to the size of the suture. Future generations of the robotic system may eliminate these differences.