What is the difference between a hypertrophic and keloid scar?

We all have a scar somewhere on our body.
Scarring is a natural process that the body undergoes when healing from a wound. On the skin, scar tissue is mostly made of collagen. The collagen is a protein which is produced to close the edges of a wound to protect us from infection.

Hypertrophic and keloid scar tissue sometimes forms when wound healing is delayed and / or excessive collagen is produced. This more likely occurs when there is damage to the deeper layers of skin or following an infection.  The excess collagen production results in a scar becoming raised, thick and often darker than the surrounding skin.
These scars are not dangerous, however can cause discomfort and limit movement. And for some people had a negative psychological impact.

Hypertrophic scar
Hypertrophic scars are thick, hard, raised, can be smooth or rough and are frequently darker than the surrounding skin (pink to deep purple). They often occur following a deep cut (laceration), surgical scar or burn. Hypertrophic scars are most likely to form over mobile joints where the skin is required to stretch and move as the joint below changes position.

Keloid scar
A keloid scar differs from other scars in that it exceeds the border of the original wound. That is, it grows larger than the initial area of injury. These scars are always dark, raised and thick, they can be rubbery, shiny and may be itchy and are sometimes even painful. Keloid scars often result from the site of a pimple, insect bite or piercing.

The good news is that there are strategies to help manage the way a scar grows and matures. Seeking guidance from a professional who has experience in burns & scar management will get you set with what you can do to help minimise the appearance of your scar.