Computer aided modeling and analysis of a new biomedicaland surgical instrument

doi:10.4236/jbise.2011.42017

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J. Biomedical Science and Engineering, 2011, 4, 119-121

doi:10.4236/jbise.2011.42017 Published Online February 2011 (http://www.SciRP.org/journal/jbise/

JBiSE

Published Online February 2011 in SciRes. http://www.scirp.org/journal/JBiSE

Computer aided modeling and analysis of a new biomedical

and surgical instrument

Zheng L i

University of Bridgeport, Bridgeport, USA.

Email: [email protected]

Received 12 November 2010; revised 15 November 2010; accepted 19 November 2010.

ABSTRACT

This paper describes the recent research and devel-

opment of an endo surgical/biomedical instrument in

surgical suture applications for minimally invasive

therapy procedure. The newly developed instruments

can not only protect the wound during the surgical

procedure but also actively help the healing process.

The new mechanism design of the surgical instrument

aids in better ergonomic design, reliable functionality,

and continuous cost reduction in product manufac-

turing. 3-D modeling technique, func tionality an alysis,

kinematical simulation and computer aided solution

have been applied to the instrument design, devel-

opment and future improvement to meet the specific

requirements of minimally invasive surgery proce-

dure. The improved new endo surgical/biomedical

instrument can prevent patient’s vessels and tissues

from being damaging because the distal move of clips

are well controlled without clip drop-off incident.

Plus the operational force to form the clip is lower

than regular surgical/biomedical instruments due to

this special new mechanism design. In addition to the

above, the manufacturing and product cost can be

decreased because the dimensional tolerance of com-

ponents, such as clip channel and jaw guide track,

can be loose due to this new instrument design. The

prototypes of this new endo surgical/biomedical in-

strument design are analyzed through computer

aided modeling and simulation, in order to prove its

feasible functionality, reliable performance, and me-

chanical advantage. All these improved features have

also been tested and verified through the prototypes.

Keywords: Hemostasis; Endoscopic Device;

Computational Simulation; 3-D Modeling; Mechanical

Advantage

1. INTRODUCTION

The newly developed technologies have directed mini-

mally invasive surgeries [1]. The positive and feasible

changes in surgical instruments have led to the new de-

velopment of surgical techniques [2] and [3]. The bio-

medical and surgical instrument market is always ad-

justed and controlled for its functionality, performance,

feasibility, quality, safety, and manufacturing cost. The

surgical instrument market is very competitive, price

sensitive and depicted by advanced technologies [4] and

[5]. Biomedical and surgical instrument is technology

based product and normally advanced techniques are

especially required to develop special technology to

compete the products in today’s challenging market [6].

The applications include the closure of tissue defects,

perforations, and anastomotic leakage in the esophagus

and stomach. The endo surgical instrument has also been

used to prevent post-polypectomy bleeding, placement

of enteral feeding tubes. The recent studies show the

versatility of endo surgical clips in therapeutic and en-

doscopic applications.

This endo surgical instrument is the innovative product

that will allow for greater ease of use for surgeons and

help to improve patient outcomes. Based on the field and

clinical feedback, the new technology that simultaneously

opens and aligns the jaws has been implemented, allow-

ing well controlled surgical clip feeding and closure. This

new surgical instrument design can provide more con-

sistent and reliable mechanism to protect the clip from

external and unanticipated disturbance while the surgical

clip sits in the jaw track.

Endo surgical instrument has been widely used in

hemostasis during endoscopy of the upper and lower

gastrointestinal tract in which the bleeding lesions can be

successfully clipped. The alternatives to endoscopic

clipping of peptic ulcers are thermal therapy (such as

electrocautery to burn the vessel causing the bleeding),

or injection of epinephrine to constrict the blood vessel.

Comparative studies between endo surgical clips and

thermal therapy verify that endo surgical clips cause less

trauma to the mucosa around the ulcer than electrocau-

tery.

J. Li et al. / J. Biomedical Science and Engineering 4 (2011) 119-121

120

2. ANALYSIS OF ENDO SURGICAL

INSTRUMENT

The operation procedure of endoclip instrument is de-

scribed as follows. An endo surgical clip is loaded onto

an endo surgical instrument and retracted into a protec-

tive sheath. The instrument is inserted through the open

channel of an endoscope. Forcing the sheath backwards

through the handle can drive the clip from the sheath.

Pulling the clip back can open the prongs. When instru-

ment jaw tips fully open, the distance between the clip

prongs reaches the maximum. The orientation of the

endo surgical clip prongs can be controlled by turning

the instrument handle clockwise. The surgical clip can

be closed by fully pull the clip proximally. In hemostasis

application, the endo surgical clip is used to compress

and clamp a bleeding vessel. If the vessel is clamped

properly, the ligation should be permanent. Compared

with the thermal and injection ligation, the endo surgical

clip is the direct mechanical method that can reduce the

injury to the near tissue. Endo surgical clips have been

positively applied in the control of GI bleeding from

multiple sources including peptic and stomal ulcers, le-

sions, gastric tumors, colonic diverticula, solitary rectal

ulcers, and post-sphincterotomy bleeding.

The Figure 1 shows new endo surgical instrument,

Figure 2 indicates the cross-section of new endo surgi-

cal instrument, and Figure 3 displays the jaw mecha-

nism section.

Figure 1. New endo surgical instrument.

Figure 2. Cross-section of new endo surgical instrument.

Figure 3. New endo surgical instrument jaw mechanism.

3. COMPUTER AIDED MODELING AND

SIMULATION

load linear

N*V M*





(1)

pivotpivot angular

M *N*r*N*V





 (2)







loadangular linearpivotpivot

N=VV*N =Vr*N (3)

The computer aided modeling and optimal simulation

of S and r combination can help to reduce the opera-

tional force and determine the minimum instrumental

handle force Ffinger that surgeon needed to operate the

surgical instrument. The computer aided solution indi-

cated that S = 4.90 inch and r = 2.15 inch for best in-

strument performance.

Based on equation (3),

490215

finger pivot

N*.N*.

Referring equation (4),





228

load pivotfinger

NVr*NVr* .*N (

The velocity ratio of





angular linear

can be found

through computer aided modeling and simulation to de-

termine the optimal instrument function. The computa-

tional solution is indicated in Figure 5.

Then the mechanical advantage of this new surgical

instrument is as follows:



228

04940035482 283 175

echanical ad vant ageVR*.

..*. .





(5)

This result indicated that the surgeons only need 3.149

lbf closure forces when 20 lbf forces are required to fully

form the surgical clip. This is lower than normal spec of

4 lbf and it will benefit surgeons in their surgical opera-

tion and procedure. Furthermore, the computer aided

modeling and simulation results are very close to the

prototype testing results that verify the credibility and

reliability of this new endo surgical and biomedical in-

strument. The prototype units have been sent to the sur-

J. Li et al. / J. Biomedical Science and Engineering 4 (2011) 119-121

121

JBISE

Figure 4. Linear and angular velocity vs. time in instrument

operation.

geons and clinic fields for more evaluations and feed-

backs. Future modification will be anticipated to further

improve instrumental function and reduce the unit cost.

4. CONCLUSION

This paper introduces a new endo surgical instrument

design using 3D computer modeling and simulation. 3D

modeling and computer aided simulation can benefit

geometrical, kinematical and dynamical analysis in con-

ceptual and feasible design of biomedical and surgical

instruments. The geometric, kinematical, dynamical and

visual limitations of the surgical instruments are ana-

lyzed to assist the surgeon in surgical procedure. The

kinematics of precision instrumental mechanism design

can be simulated and modeled as either an open or

closed-loop joint chain with some rigid bodies connected

to each other in a series format, driven by actuated

mechanism. The analysis of kinematical structure in

mechanism can provide a systematic and general ap-

proach to determine and calculate mechanism motion

functionality. The kinematical and dynamic simulation

of these multiple link system permits conceptual verifi-

cation and feasible studies in the design and develop-

ment stage. The computer aided simulation and proto-

type testing have shown the feasible and reliable func-

tion of this new endo biomedical and surgical instru-

ment.

REFERENCES

[1] Lin, H.J., Lo, W.C., Cheng, Y.C. and Peng, C.L. (2007)

Endoscopic hemoclip versus triclip placement in patients

with high risk peptic ulcer bleeding. Journal of Gastro-

enterology, 102, 539-543.

[2] Charabaty-Pishvaian, A. and Al-Kawas, F. (2004) Endo-

scopic treatment t of duodenal perforation using a clip-

ping device: Case report and review of the literature.

South Medical Journal, 97, 190-193.

doi:10.1097/01.SMJ.0000091031.77846.B6

[3] Dhalla, S.S. (2004) Endoscopic repair of a colonic per-

foration following polypectomy using an endoclip. Jour-

nal of Gastroenterology, 18, 105-106.

[4] Saltzman, J.R., et al. (2005) Prospective trial of endo-

scopic clips versus combination therapy in upper GI

bleeding. Journal of Gastroenterology, 100, 503-509.

[5] Fu, F.H. and Jordan, S.S. (2007) The lateral intercondy-

lar ridge—A key to anatomic anterior cruciate ligament

reconstruction. Journal of Bone and Joint Surgery, 89,

2103-2104. doi:10.2106/JBJS.G.00851

[6] Farrow, L.D., Chen, M.R., Cooperman, D.R., Victoroff,

B.N. and Goodfellow, D.B. (2007) Morphology of the

femoral intercondylar notch. Journal of Bone and Joint

Surgery, 89, 2150-2155. doi:10.2106/JBJS.F.01191

Nomenclature

M: inch-lbf, torque on pivot point of trigger

Nload: lbf, force required to close the jaws

S: inch, distance between trigger pivot center and surgeon’s finger position

Npivot: lbf, normal force on linkage pivot

ω: degree per second, angular speed of trigger at pivot center

Nfinger: lbf, force on surgeon’s finger

Vlinear: inch per second, distal linear moving speed of instrument drive bar

(Vr): velocity ratio

r: inch, center distance between trigger pivot and linkage pivot

Vangular: inch per second, angular tangential speed at trigger pivot center