Biomedical Engineering Reference
In-Depth Information
appeared in the 1980s up until the study by Vilos et al., in which a series of
intramural-isthmic fallopian-tube anastomoses were performed with a patency
rate of 100% [90]. The main problem claimed in these studies appeared to
be the nonuniform heating of the tissue. Improved results were obtained by
introduction of a low-power diode laser in conjunction with a protein solder
in a rabbit model [91]. In this study, no thermal damage was detected, while
a significant reduction in the operative time was evidenced.
15.4.3 Laser Welding in Neurosurgery
The major advantage of using laser welding on nerves is the much shorter time-
consumption for operation when compared with conventional microsuturing
techniques. However, as high power densities are required to coapt the nerve
edges, thermal damage in the epineurium is easily induced [92]. In contrast,
low power does not result in su
cient tensile strength. To improve nerve
welding, usage of sealing material was proposed. The most popular solders
are dye-enhanced protein solders, which were employed either with CO
2
or
diode laser [28,93]. The bonding rate and the functional recovery of the nerves
subject to laser soldering are superior to those of manual suturing techniques,
while the risk of inflammation and foreign body reaction are minimized [93].
15.4.4 Laser Welding in Orthopaedic Surgery
Other investigations of the laser tissue welding technique have been carried
out in the case of orthopaedic surgery. The welding of tendinous tissue was
investigated using a Nd:YAG laser alone [94] or in conjunction with an albu-
min solder, and an argon laser in conjunction with a fluorescein-dye-doped
albumin solder [95]. These studies pointed out the inability of the laser tech-
nique to produce a weld of su
cient strength to withstand the significant
tensile loads, which tendons are subjected to from immediately after the re-
pair. Laser welding of meniscus tears using an argon laser in conjunction with
a fibrinogen solder gave similar results [16].
15.4.5 Laser Welding of the Skin
The principal advantage claimed for the laser welding of skin is a superior cos-
metic result. However, control of the temperature enhancement at the weld
site is challenging. It is nearly impossible to obtain full-thickness welds and
limit thermal denaturation laterally around the weld site in the epidermis
and papillary dermis. Although thermal denaturation of tissue is necessary
in order to produce a strong weld, excessive thermal damage may result in
scarring and dehiscence [96]. The use of chromophores has been proposed to
minimize unwanted collateral thermal injury ensuring selective laser absorp-
tion at the same time [4, 96]. The application of a variety of solders has also
