A bulge at the dorsum of the foot with a sprained instep may be caused by soft tissue swelling, joint dislocation or fracture.
1. Soft tissue swelling: when the instep is sprained, some joints may be subject to stress injury, resulting in strains or tears of ligaments, muscles and other soft tissues around the joints, and aseptic inflammatory reaction occurs in some tissues. With the increase of inflammatory exudate, swelling will occur at the sprain, usually manifested as a bulge at the instep.
2. Joint dislocation or fracture: Generally, joint dislocation or fracture may occur after spraining the back of the foot, the joint dislocation part or fracture broken end will appear at the back of the foot, resulting in bulging at the back of the foot.
There may be other reasons for the bulge on the back of the foot after a sprain, so it is recommended to actively seek medical attention to clarify the cause of the disease and then carry out regular treatment.