What are the most common causes of poor healing?

A variety of things. Poor healing can be due to diet deficiencies (protein, vitamin), diabetes, drugs (corticosteroids, coumadin, (warfarin) chemotherapy) inappropriate treatment (wet to dry, dakin's, continued pressure) bacterial load or biofilm, osteomyelitis, age, disease (infection elsewhere, heart or arterial, metabolic) autoimmune (lupus, psoriasis, pyoderma, .
Diab, Infec, low O2. Anemia cancer chemotherapy corticosteroids denervation diabetes collagen vascular disorders r a rh arthritus sle lupus scleroderma dermatomyositis polyarteritis nodosum infection ischemia obesity poor nutrition pressure radiation vasoconstrictive states uremia hypercalcemia.