Begin by preparing two retention holders. Use light wire pliers and a 0.014 inch Australian wire to make a helical loop. Then prepare customized stainless steel springs and cut the spring into an appropriate length.
Also prepare one straight Australian wire or straight steel wire of length seven millimeters and cut two pieces of paper with diameters of two millimeters to use as barriers. Next, place an anesthetized mouse on the operating table and carefully remove the fur on top of the head with hair removal cream or a shaver. Then disinfect the scalp of the mouse using alternating rounds of Iodoform and 75%alcohol.
Position the mouse with its head on the top and use surgical tapes to fix the limbs on the operating table. Now, use surgical scissors to perform an arcuate flap along the scalp near the neck of the mouse, fully exposing the sagittal suture and surrounding skull. Then, fix the scalp flap with a 6-0 suture on the operating table.
Dry the skull and etch it with 37%phosphoric acid for 20 seconds. Then use normal saline to clean up the acid etching. Place the two holders on both sides of the parietal bones, three millimeters from the sagittal sutures and glue them with a light cured adhesive.
Then put back the scalp flap. Label the position of the holders and cut two small holes in the scalp at the corresponding positions. Reset the flap scalp by simultaneously passing the small loops through the holes to expose the skin surface.
To install the spring and guide wire, cut the spring one millimeter longer than the distance between the two holders. Compress the pressure spring and place it between the small coils on both sides. Pass the stainless steel wire through the small coils and the spring and release the spring to obtain a starting thrust of about 30G.
Next, place two scraps of paper between the spring and the holders and bond them with a light cured adhesive to set up barriers at both ends of the spring. After expansion, micro CT was used to visualize the changes in the cranial suture. In comparison to controls, the cranial suture gradually and significantly expanded after applying force for one day and fluffy bony protrusions appeared on the bone edge after day five.
Also, visualization of mineralization using double labeling method, showed that force loading significantly activated osteogenesis. Newly mineralized bone was observed after seven days, indicating the bone remodeling process after suture expansion.
