T E C H

A Performance Comparison Between Reprocessed and New Covidien LigaSure™ 5mm Blunt Tip Laparoscopic Sealer/Divider (1637)

E V I D E N C E R E P O R T

The Stryker Sustainability Solutions Reprocessed LigaSure™

5mm Blunt Tip Laparoscopic Sealer/Divider (LF1637) is a

bipolar electrosurgical instrument intended for use with the

ForceTriad™ Energy Platform in general (including urologic,

vascular, thoracic, and thoracoscopic) and gynecologic

laparoscopic surgical procedures where ligation and division

of vessels and lymph is desired. The instrument creates a

seal by application of RF electrosurgical energy to vascular

structures (vessels and lymph) interposed between the jaws

of the instrument. A blade within the instrument is surgeon

actuated to divide tissue.1

This evidence report outlines the extensive testing

performed to demonstrate substantially equivalent functional

performance of Reprocessed LigaSure™ 5mm Blunt Tip

Laparoscopic Sealer/Divider (LF1637) in comparison to

the Original Manufacturer’s (OM) device, which has not

been reprocessed. Wide-ranging bench-top tests were

conducted to validate the following functional attributes:

• Vessel burst pressure

• Thermal spread and jaw temperature

• Blade and jaw functionality

• Electrical resistance and safety

• Overall device reliability and functionality

INTRODUCING THE REPROCESSED LIGASURE™ 5mm BLUNT TIP VESSEL SEALER/DIVIDER (LF1637)

T E C HE V I D E N C E R E P O R T

Electrical resistance testing is performed to verify that each

device provides a continuous conductive pathway, ensuring

proper functionality during each seal. This is performed

as part of the manufacturing process, where each device

(100%) is tested as part of the in-line inspection criteria.

Dielectric withstand testing is also performed on each

device (100%) to ensure integrity of the electrical wire

insulation. The customized testing apparatus and test

method follows industry-accepted criteria referenced in the

electrical safety standard, IEC 60601 (Medical Electrical

Equipment Standard), published by the International

Electrotechnical Commission. Dielectric withstand testing

is important to not only ensure each device functions as

intended after reprocessing, but that it is safe to use on the

patient, as well as safe to handle by the clinical user.

Electrical Resistance and Safety

References1. VSD EL10029 Rev. A 04-2015 RM702135 - Instructions For Use - SSS Reprocessed LigaSure™ Blunt Tip Laparoscopic Sealer/Dividers (Model LF1637)2. Kim F J, Chammas M F Jr., Gewehr E, et al. Temperature safety profile of laparoscopic devices: Harmonic ACE (ACE), LigaSureTM V (LV), and plasma trisector (PT).

Surg Endosc 2008, 22:1464-14693. Reports on File. (T14398, T14336)4. Eick S, Loudermilk B, et al. Rationale, bench testing and in vivo evaluation of a novel 5 mm laparoscopic vessel sealing device with homogeneous pressure distribution in

long instrument jaws. Annals of Surgical Innovation and Research 2013, 7:15

Figure 1. Inline electrical testing

To demonstrate the Reprocessed LF1637 device’s

ability to safely and reliably seal a wide range of vessels,

including those larger in diameter, testing was conducted

using porcine carotid and iliac vessels, ranging in size

from 2-7mm diameter.

The Reprocessed LF1637 devices were compared to OM

LF1637 devices in order to evaluate substantial equivalence

of functionality between the two test groups. During the

testing, vessels were first sealed and cut, followed by

pressurizing the vessel by infusing with saline until the vessel

ruptured, while measuring and recording peak pressure.

Before the vessel burst, the maximum internal vessel pressure

was determined using a customized burst pressure fixture.

Vessel burst pressure results were required to demonstrate

substantial equivalency, or better than the OM device.

Larger (elevated) internal vessel pressures indicate a

stronger seal. A Mann-Whitney Test was used to analyze

the median distribution comparison between the groups,

which demonstrated significance with a p-value greater

than (>) 0.05, indicating the distribution’s medians were not

statistically different, and therefore, no statistical difference

between the two groups.

Vessel Burst Pressure

5. Sindram D, Martin K, Meadows JP, et al. Collagen-elastin ratio predicts burst pressure of arterial seals created using a bipolar vessel sealing device in a porcine model. Surg Endosc 2011; 25:2604-2612.

6. Latimer C, Nelson M , Moore C, et al. Effect of collagen and elastin content on the burst pressure of human blood vessel seals formed with a bipolar tissue sealing system. Journal of Surgical Research 2014; 186:73-80.

7. Rothmund R, Schaeller D, Neugebauer AA, et al. Evaluation of thermal damage in a pig model. J Invest Surg. 2012; 25(1):43-50.8. Lamberton GR, Hsi RS, Jin DH, Lindler TU, et al. Prospective comparison of four laparoscopic vessel ligation devices. J Endourol. 2008; 22(10):2307-2312.

Device Type N mmHg P value

Reprocessed (RP) LF1637 59 519.4

0.1112

OM LF1637 30 391.7

Table 1. Vessel Burst Pressure Results Summary

Figure 1. Inline electrical testing

1800

1600

1400

1200

1000

800

600

400

200

0

1800

1600

1400

1200

1000

800

600

400

200

0

Figure 2. Box Plot Comparison – Vessel Burst Pressure

LF1637 Burst Pressure Comparison (OM vs Reprocessed)Seal Quality (Burst of Seal in mmHg Pressure)

LF1637 OM Burst Pressure (mmHg)

Dat

a

LF1637 RP Burst Pressure (mmHg)

Lateral thermal damage can occur as a result of protein

denaturing in tissue, when sealing temperature reaches

above 60°C (140°F).2 This is a critical functional attribute to

consider when advanced energy devices are activated near

vital organs and structures, especially when used in a wide

range of procedures.

Porcine carotid and iliac vessels, ranging in diameters from

2mm to 7mm, were used to evaluate the distance of thermal

spread of tissue after a complete seal for both reprocessed

and OM devices. Infrared thermal images were recorded

using an infrared camera. An infrared camera along with

customized fixturing and validated software were employed

to capture, calculate, and analyze the maximum distance

from the middle of the device jaws to where the tissue

surrounding the jaws reached a temperature that would result

in protein denaturation in tissue (> 60 °C (140°F)).

Additionally, maximum jaw temperature testing was

performed to evaluate the maximum temperature of the

device jaw component during sealing of porcine carotid

and iliac vessels ranging from 2-7mm diameter. Infrared

images of each device’s thermal footprint was recorded

with a FLIR Infrared Camera using customized fixturing

and analyzed using a customized, mathematical software

program. Acceptance criteria dictated that the maximum jaw

temperature during a complete seal cycle shall be equivalent

to or less than the OM.

For both test methods, a total of N=29 OM samples were

compared to N=59 reprocessed samples and were evaluated

using a Mann-Whitney test for significance. Both reprocessed

and OM samples performed substantially equivalent to

each other when comparing medians, with p-values greater

than (>) 0.05, indicating the distribution’s medians were not

statistically different.

Thermal Spread and Jaw Temperature

MKT20150606A

Figure 3. Thermal footprint of distal jaw grasping vessel using FLIR camera (˚F) Figure 4. Image of jaw grasping vessel

As part of the manufacturing process for Reprocessed

LF1637 devices, the cutting blade and some distal tip

subassembly components are removed and discarded

during disassembly of the device prior to the other device

components entering the decontamination and cleaning

steps. These are replaced with brand new, equivalent

components during reassembly of the device, prior to in-line

function testing. The specifications (geometries, dimensional

tolerances, material, etc.) of these replacement components

were derived through reverse engineering the OM devices,

and therefore, are designed to be substantially equivalent to

those originating in an OM device.

As part of the validation activities performed to prove

substantial equivalency of the components, the replacement

blade and distal tip sub-assembly components underwent

extensive testing, in comparison to an OM device. The

following evaluations were performed, and have met the

established acceptance criteria based on bench-top testing

data of an OM device:

• Cut quality - This test evaluated the quality of a cut made

by the replaced blade.

• Blade deployment - This test evaluated the distance that

the blade travels within the jaw assembly when the blade

trigger is fully engaged.

• Blade trigger force - This test assessed the forces

required to engage the blade trigger.

• Blade trigger force through media - This test assessed

the forces required to engage the blade trigger when the

blade is cutting through media.

• Jaw opening angle – This test evaluated the angle

between the upper and lower jaws when the jaw is

completely open.

• Force to open jaws - This test assessed the forces

required to open the jaws.

• Jaw clamp force – This test assessed the forces that

are translated through the shaft of the device to the jaws

when the jaw trigger is engaged.

Blade and Jaw Functionality

Figure 5. Jaw force testing on the Instron (close-up) Figure 6. Jaw force testing on the Instron

R E P R O C E S S E D S U R G I C A L D E V I C E S

T E C HIn order to demonstrate overall device reliability and

functionality of the Reprocessed LF1637 device, extensive

simulated clinical cycle testing was performed, where each

reprocessed device was cycled through 120 simulated-use

actuations, intended to exceed a typical clinical use.

Each device was then evaluated to confirm the following

critical functional attributes:

• Seal cycle completion

▪ Appropriately sized vessels/tissue is adequately sealed.

▪ Device provides audible feedback for the cautery

button activation.

• Blade deployment

▪ When jaws are closed, blade deploys and retracts to

normal position

▪ When jaws are open, blade is not deployed

(safety mechanism)

• Grasping mechanism

▪ Device provides audible and tactile feedback for the jaw

locking/unlocking function

▪ Jaw release mechanism of grasped vessel/tissue when

handle is unlocked

• Unintended electrical energy transmission does not

occur through various feature combinations when

activation button is:

▪ activated, jaws are either open or closed (locked), and no

vessel/tissue is grasped.

▪ not activated, jaws are either open or closed (locked),

and no vessel/tissue is grasped.

▪ not activated, jaws are either closed (locked), and vessel/

tissue is grasped.

• Cable connection and generator recognition

▪ Cable inserts into generator as intended and remains

securely connected to the ForceTriad during use.

▪ Device is recognized by the ForceTriad Generator

software version 3.50 or greater.

▪ Jaw rotation

▪ User can rotate jaws when jaw trigger is unlocked.

• Compatibility with trocar accessory

▪ Device can be inserted and withdrawn through the

cannula of a 5 mm trocar, as intended.

▪ Force required to insert a device through a 5mm trocar is

measured.

Additional testing was performed on the rotator knob and

handle lock mechanisms:

• Rotator Knob

▪ Testing was performed to assess forces required to rotate

the rotator knob throughout its entire range of motion,

in addition to the amount of rotation (measured through

linear displacement) that is possible throughout the entire

range of motion.

• Handle Lock/Unlock Force

▪ Testing was performed to assess the forces required to

engage/disengage and lock/unlock the jaw trigger.

Overall Device Reliability and Functionality

sustainability.stryker.com • 888.888.3433