» I was also under the impression that primary intention was when an
» incision healed with no closure (suture, staples, etc.) and secondary
» intention was healing through some mechanical means. What is the official
» medical/surgical definition?
Nope, no cigar!
Primary intention healing occurs with a surgical incision or other clean “slice” wound (eg, strip harvest, superficial knife wound). Edges are approximated and heal together. If an infection occurs, however, the wound must be opened in order to drain. This is not consistent with primary healing at this point. Granulation tissue forms at the base and along the sides of the wound, and fills in gradually over time. If one attempts to approximate the wound at this point, well… it ain’t gonna happen! Scars which form from this process are not very aesthetic (ie, ugly).
Secondary intention occurs when there are not smooth wound edges to approximate with sutures, staples, tissue glue, etc. Examples would be punch woulds, ulcers, gouges or avulsion wounds. This process described above takes place, and the granulation tissue fills in the wound over time. Scars resulting tend to contract more than those from primary healing.