A thigh strain or quadriceps strain is a tear in one of the quadriceps muscles at the front of the thigh. It can range from a mild discomfort to a full blown tear of most of the muscle resulting in severe pain and inability to walk.
The breakage of the stitches starts within 2 weeks of the stitching but if you want the complete stitches to disappear then the process of hydrolysis or the enzymes in our body do that in a period of 60 days and therefore it approximately takes up to 2 months for the stitches to get dissolved.
Summing up, making dissolvable stitches dissolve quicker is somehow unadvised. You can always ask your doctor to take it out, but this might prevent the wound from naturally healing. Instead, take care of the wound properly so that it heals faster and thus, you can get the stitches removed faster as well.