Complications of Wound Healing 
 
Abnormalities in any of the three basic healing processes – contraction, repair, and regeneration – result in the complications of wound healing.  
 
1. Infection 
A wound may provide the portal of entry for many organisms. Infectrion may delay healing, and if severe stop it completely.  
 
2. Deficient Scar Formation  
Inadequate formation of granulation tissue or an inability to form a suitable extracellular matrix leads to deficient scar formation and its complications. The complications of deficient scar formation are: 
  a. Wound dehiscence & incitional hernias 
  b. Ulceration  
 
a. Wound Dehiscence and Incisional Hernias: 
  
Dehiscence (bursting of a wound) is of most concern after abdominal surgery. If insufficient extracellular matrix is deposited or there is inadequate cross-linking of the matrix, weak scars result. Dehiscence occurs in 0.5% to 5% of abdominal operations.Inappropriate suture material and poor surgical techiniques are important factors. Wound infection, increased mechanical stress on the wound from vomiting, coughing, or ileus is a factor in most cases of abdominal dehiscence. Systemic factors that predispose to dehiscence include poor metabolic status, such as vitamin C deficiency, hypoproteinemia, and the general inanition

that often accompanies metastatic cancer. Dehiscence of an abdominal wound can be a life-threatening complication, in some studies carrying a mortality as high as 30%.  
An incisional hernia, usually of the abdominal wall, refers to a defect caused by poor wound healing following surgery into which the intestines protrude.  
 
b. Ulceration:  
Wounds ulcerate because of an inadequate intrinsic blood supply or insufficient vascularization during healing. For example, leg wounds in persons with varicose veins or severe atherosclerosis typically ulcerate.  Nonhealing wounds also develop in areas devoid of sensation because of persistent trauma. Such  trophic or neuropathic ulcers are occasionally seen in patients with leprosy, diabetic peripheral neuropathy and in tertiary syphilis from spinal involvement (in tabes dorsalis). 
 
3. Excessive Scar Formation  
 
An excessive deposition of extracellular matrix at the wound site results in a hypertrophic scar or a keloid (See Figure 4-5 and 4-6). The rate of collagen synthesis, the ratio of type III to type I collagen, and the number of reducible cross-links remain high, a situation that indicates a “maturation arrest”, or block, in the healing process.  
 
Keloid Formation 
An excessive formation of collagenous tissue results in the appearance of a raised area of scar tissue called keloid.    It is  an exuberant scar that tends to progress and recur after excision. The cause of this is unknown.  Genetic predisposition, repeated trauma, and irritation caused by foreign body, hair, keratin, etc., may play a part. It is especially frequent after burns. It is common in areas of the neck & in the ear lobes. 
 
Hypertrophic Scar 

Hypertrophic scar is structurally similar to  keloid. However, hypertrophic scar never gets worse after 6 months unlike keloid, which gets worse even after a year and some may even progress for 5 to 10 years. Following excision keloid recurres, whereas a hypertrophic scar does not.

4. Excessive contraction  
 
A decrease in the size of a wound depends on the presence of myofibroblasts, development of cell-cell contacts and sustained cell contraction. An exaggeration of these processes is termed  contracture (cicatrisation)  and results in severe deformity of the wound and surrounding tissues. Contracture (cicatrisation) is also said to arise as a result of late reduction in the size of the wound.  Interestingly, the regions that normally show minimal wound contraction (such as the palms, the soles, and the anterior aspect of the thorax) are the ones prone to contractures. Contractures are particularly conspicuous in the healing of serious burns. Contractures of the skin and underlying connective tissue can be severe enough to compromise the movement of joints. Cicatrisation is also important in hollow viscera such as urethra, esophagus, and intestine. It leads to progressive stenosis with stricture formation. In the alimentary tract, a contracture (stricture) can result in an obstruction to the passage of food in the esophagus or a block in the flow of intestinal contents. 
Several diseases are characterized by contracture and irreversible fibrosis of the superficial fascia, including Dupuytren disease (palmar contracture), plantar contracture (Lederhosen disease), and Peyronie disease (contracture of the cavernous tissues of the penis). In these diseases, there is no known precipitating injury, even though the basic process is similar to the contracture in wound healing.  
 
5. Miscellaneous 
 
Implantation (or epidermoid cyst: Epithelial cells which flow into the healing wound may later 
sometimes persist, and proliferate to form an epidermoid cyst.