Therapeutic low energy laser improves the mechanical strength of repairing medial collateral ligament.
OBJECTIVE
Low energy laser therapy has been shown to enhance collagen production but its effect on tissue strength is not well reported. We tested the effects of therapeutic laser on the strength of healing medial collateral ligaments (MCLs) in rats.


METHODS
Twenty-four rats received surgical transection to their right MCL and eight received sham operation. After surgery, 16 received a single dose of gallium aluminum arsenide laser to their transected MCL for 7.5 minutes (n = 8) or 15 minutes (n = 8) and eight served as control with placebo laser, while the sham group didn't receive any treatment. The MCLs were biomechanically tested at either 3 or 6 weeks post-operation.


RESULTS
The normalized ultimate tensile strength (UTS) and stiffness of laser and sham groups were larger than control (P < 0.001). The UTS of laser and sham groups were comparable. Laser and sham groups had improved in stiffness from 3 to 6 weeks (P < 0.001).


CONCLUSIONS
A single dose of low energy laser therapy improves the UTS and stiffness of repairing MCL at 3 and 6 weeks after injury.
Fung
Dicky T C
DT
Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Ng
Gabriel Y F
GY
Leung
Mason C P
MC
Tay
David K C
DK
D000818:Animals; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D004548:Elasticity / Q000528:radiation effects; D028022:Low-Level Light Therapy; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000293:injuries* / Q000528:radiation effects* / Q000601:surgery; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000528:radiation effects*; D013997:Time Factors; D014783:Viscosity / Q000528:radiation effects; D014945:Wound Healing / Q000528:radiation effects*