The length of the graft and the length of the tunnel in the thigh bone vary from patient to patient. It is important to get a good length of the graft material in both the shin and thigh bones so as to give the best chance of the graft attaching to the surrounding bone. With the fixed loop system, once the metal button attached to the outer thigh bone is in place, the length of the loop cannot be adjusted. Thus the amount of hamstring graft in either end of the bony tunnel cannot be changed. One potential advantage of an adjustable loop system is that the amount of graft in either end of the bone tunnel can be altered to ensure sufficient graft is accurately placed.