A retractor system for use in spinal surgical procedures includes at least two retractor blades, each of the at least two retractor blades, a shim and a shim inserter. The shim has an expansion band and the shim inserter is configured to slide the shim between and along the at least two retractor blades and dispose the shim at a distal end of the at least two retractor blades. The shim spreads the at least two retractor blades away from each other when the shim insert slides the shim between and along the at least two retractor blades and the shim prevents the distal end of each of the at least two retractor blades from closing in on each other due to musculature load when the shim is disposed at the distal end of the at least two retractor blades.