When people get a cut they ask, "Does my cut need stitches?" Many times a simple bandage will work just as well. Stitches are used to control bleeding, to reduce the chance of infection, and generally to leave a smaller scar. There are types of cuts when stitches are essential.
The wound on a scraped knee is an abrasion, usually superficial, and will heal with a simple bandage. Lacerations are what most people think of as a cut, with avulsions a chunk of skin is torn away, and punctures occur from a nail or sharp object piercing the skin. Because dog bites have a very high risk of infection if closed, antibiotics are usually given and the bite is bandaged, but not stitched. For a puncture wound, because bacteria is associated with the soles of rubber shoes, an antibiotic is given. Stitches depend on the depth of the wound.
Being able to see bone, tendon, muscle or fatty tissue from a laceration is cause for concern as is a cut wider than about 3/4 of an inch. Excessive bleeding that will not stop, loss of sensation, and risk of a foreign object stuck inside the cut signal need for medical attention. Stitching wounds applies pressure that stops the bleeding, brings the tissue back together, and helps prevent infection. Booster tetanus shots are administered if there is no memory of a tetanus shot within the past 5 to 10 years.
The development of tissue adhesives has allowed fewer stitches to be given, but work only on parts of the body that do not move a lot. A knee might benefit from stitches rather than the adhesive. If a person washes a wound and the cut appears to be healing well, in most cases it is. If there are concerns, a visit to the emergency room is in order.