Laser solder welding of articular cartilage: tensile strength and chondrocyte viability.
OBJECTIVE
The surgical treatment of full-thickness cartilage defects in the knee joint remains a therapeutic challenge. Recently, new techniques for articular cartilage transplantation, such as mosaicplasty, have become available for cartilage repair. The long-term success of these techniques, however, depends not only on the chondrocyte viability but also on a lateral integration of the implant. The goal of this study was to evaluate the feasibility of cartilage welding by using albumin solder that was dye-enhanced to allow coagulation with 808-nm laser diode irradiation.


METHODS
Conventional histology of light microscopy was compared with a viability staining to precisely determine the extent of thermal damage after laser welding. Indocyanine green (ICG) enhanced albumin solder (25% albumin, 0.5% HA, 0.1% ICG) was used for articular cartilage welding. For coagulation, the solder was irradiated through the cartilage implant by 808-nm laser light and the tensile strength of the weld was measured.


RESULTS
Viability staining revealed a thermal damage of typically 500 m in depth at an irradiance of approximately 10 W/cm(2) for 8 seconds, whereas conventional histologies showed only half of the extent found by the viability test. Heat-bath investigations revealed a threshold temperature of minimum 54 degrees C for thermal damage of chondrocytes. Efficient cartilage bonding was obtained by using bovine albumin solder as adhesive. Maximum tensile strength of more than 10 N/cm(2) was achieved.


CONCLUSIONS
Viability tests revealed that the thermal damage is much greater (up to twice) than expected after light microscopic characterization. This study shows the feasibility to strongly laser weld cartilage on cartilage by use of a dye-enhanced albumin solder. Possibilities to reduce the range of damage are suggested.
Züger
B J
BJ
Institute of Applied Physics, University of Berne, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
Ott
B
B
Mainil-Varlet
P
P
Schaffner
T
T
Clémence
J F
JF
Weber
H P
HP
Frenz
M
M
D000818:Animals; D002358:Cartilage, Articular / Q000601:surgery*; D002417:Cattle; D002470:Cell Survival; D019902:Chondrocytes / Q000502:physiology* / Q000528:radiation effects; D005240:Feasibility Studies; D007208:Indocyanine Green / Q000494:pharmacology; D053685:Laser Therapy / Q000379:methods*; D013718:Tensile Strength
D007208:Indocyanine Green