Healing of incisional wounds in stomach and duodenum: influence of long-term healing on mechanical strength and collagen distribution.

Mechanical properties, rupture pattern (morphologic characteristics) and distribution of collagen concentration in incisional wounds of rat stomach and duodenum after 80 days of healing were compared with previous observations on 40-day wounds and with intact tissue. Increased energy absorption (breaking energy) was found in wound tissue of stomach and duodenum after 80 days. No other differences were found between 40 and 80 days of healing. The weakest point of the healing wound was 4-5 mm lateral to the incision line, in the margin of the biochemically active zone. The results indicate that the functionally important part of the healing process in stomach and duodenum occurs early, but some activity persists for at least 80 days postoperatively. The main activity in late wound healing probably is remodelling of scar tissue, completing restoration of tissue strength. Suture materials and technique are unimportant for late healing phases in stomach and duodenum. It is emphasized that a detailed biomechanical account of wound properties is necessary to describe the development of a wound's mechanical strength.