Page 187 - Textbook of Pathology, 6th Edition

2. Poor blood supply to wound slows healing e.g. injuries to Fracture Healing 171
face heal quickly due to rich blood supply while injury to Healing of fracture by callus formation depends upon some
leg with varicose ulcers having poor blood supply heals clinical considerations whether the fracture is:
slowly. traumatic (in previously normal bone), or pathological (in
3. Foreign bodies including sutures interfere with healing and previously diseased bone);
cause intense inflammatory reaction and infection. complete or incomplete like green-stick fracture; and CHAPTER 6
4. Movement delays wound healing. simple (closed), comminuted (splintering of bone), or
5. Exposure to ionising radiation delays granulation tissue compound (communicating to skin surface).
However, basic events in healing of any type of fracture
formation. are similar and resemble healing of skin wound to some
6. Exposure to ultraviolet light facilitates healing. extent.
7. Type, size and location of injury determines whether Primary union of fractures occurs in a few special
healing takes place by resolution or organisation. situations when the ends of fracture are approximated as is
B. SYSTEMIC FACTORS: done by application of compression clamps. In these cases,
1. Age. Wound healing is rapid in young and somewhat bony union takes place with formation of medullary callus
slow in aged and debilitated people due to poor blood supply without periosteal callus formation. The patient can be made
to the injured area in the latter. ambulatory early but there is more extensive bone necrosis Inflammation and Healing
2. Nutrition. Deficiency of constituents like protein, vitamin and slow healing.
C (scurvy) and zinc delays the wound healing. Secondary union is the more common process of fracture
3. Systemic infection delays wound healing. healing. Though it is a continuous process, secondary bone
union is described under the following 3 headings:
4. Administration of glucocorticoids has anti-inflammatory i) Procallus formation
effect. ii) Osseous callus formation
5. Uncontrolled diabetics are more prone to develop infections iii) Remodelling
and hence delay in healing. These processes are illustrated in Fig. 6.44 and described
6. Haematologic abnormalities like defect of neutrophil func- below:
tions (chemotaxis and phagocytosis), and neutropenia and I. PROCALLUS FORMATION. Steps involved in the
bleeding disorders slow the process of wound healing. formation of procallus are as follows:

1. Haematoma forms due to bleeding from torn blood
HEALING IN SPECIALISED TISSUES
vessels, filling the area surrounding the fracture. Loose
Healing of the skin wound provides an example of general meshwork is formed by blood and fibrin clot which acts as
process of healing by regeneration and repair. However, in framework for subsequent granulation tissue formation.
certain specialised tissues, either regeneration or repair may 2. Local inflammatory response occurs at the site of injury
predominate. Some of these examples are described below. with exudation of fibrin, polymorphs and macrophages. The

Figure 6.44 Fracture healing. A, Haematoma formation and local inflammatory response at the fracture site. B, Ingrowth of granulation tissue
with formation of soft tissue callus. C, Formation of procallus composed of woven bone and cartilage with its characteristic fusiform appearance and
having 3 arbitrary components—external, intermediate and internal callus. D, Formation of osseous callus composed of lamellar bone following
clearance of woven bone and cartilage. E, Remodelled bone ends; the external callus cleared away. Intermediate callus converted into lamellar
bone and internal callus developing bone marrow cavity.