**7.2. Mechanical aspects of fracture healing**

Immobilization and stabilization of bone fragments after their anatomical repositioning provide an optimal mechanical environment for the healing. Thus, casts splints, and orthopedic implants are the most effective methods of treatment.

They provide an optimal, biomechanical environment to the fracture gap, as excessive interfragmentary movements disrupt callus' vasculature. Newly formed blood vessels, built with the single layer of endothelial cells only, are very fragile. Irrespective of the direction (by side,

Fracture Repair: Its Pathomechanism and Disturbances http://dx.doi.org/10.5772/intechopen.76252 13

**Figure 4.** Fracture gap and its newly formed vasculature (red lines; a) dislocated by-side (b), rotation (c), angulation (d) and controlled axial movements (e).

**Figure 5.** Hypertrophic non-union of the non-stabilized fracture.

Properly balanced diet provides all the nutrients, vitamins, and minerals that are necessary for healing. In case of bone fracture, an attention has to be paid over calcium, phosphates (osteoid formation), proteins (source of amino acids for collagen synthesis), and vitamin D3

Starvation is nowadays relatively seldom in developed societies, whose overweight and obese population alarmingly increases. Nevertheless, it could not be forgotten that it pertains only ca one-fourth of the Earth's population, whereas the next three-fourth suffers from hunger. Moreover, starvation and malnutrition may result from other than just a food shortage,

At the risk are especially elder, handicapped (also mentally) persons, drugs or alcohol abused, patients suffering from anorexia, and all others suffering from disturbed food intake, digestion, absorption, or processing. Thus, at risk are all those suffering from various digestive disorders, including short bowel syndrome, Hirschsprung's or Crohn's diseases, liver cirrhosis, pancreatitis and many others. Diabetes also leads to some type of starvation, as intracellular

An increasing number of population implementing restrictive diet to reduce the body weight may present various nutritional deficiencies. Nevertheless, so far any religious (i.e. exclusion from the diet some kind of a meat) nor ideological (i.e. growing population of vegetarians and vegans) dietary restrictions nor customs were reported to influence bone healing. However,

Several habits affect the healing. Entering hundreds of detrimental substances, including highly toxic and carcinogenic ones, smoking impairs the function of progenitor cells, impairs local circulation, and reduces hemoglobin oxygenation disturbing reparative processes [50]. Alcohol was also shown to evoke its negative impact, but in small quantities may be beneficial

Several other addictions, including opioids, cannabinoids, and psychostimulants, indirectly influence the healing trajectories degrading the patient's psychosomatic status, and thus resulting in poverty, homelessness, malnourishment, and increased susceptibility to infections and additional injuries. Addicted persons have also limited access to health services, both due to social and economic reasons, and their irrational behavior. Moreover, some of them are not interested in successful treatment at all, as complications, when occur ease them to obtain social support.

Immobilization and stabilization of bone fragments after their anatomical repositioning provide an optimal mechanical environment for the healing. Thus, casts splints, and orthopedic

They provide an optimal, biomechanical environment to the fracture gap, as excessive interfragmentary movements disrupt callus' vasculature. Newly formed blood vessels, built with the single layer of endothelial cells only, are very fragile. Irrespective of the direction (by side,

hypoglycemia deprives cells of glucose, the most important source of energy [48].

their negative insult, especially on young individuals, should be considered [49].

supporting the fracture energetically and improving its perfusion [51, 52].

that may, in some cases, require supplementation.

**7.1. Habits disturbing healing of the fracture**

**7.2. Mechanical aspects of fracture healing**

implants are the most effective methods of treatment.

reasons.

12 Trauma Surgery

angular, rotation or distraction), displacements disrupt the microvasculature that deprives the fracture of blood supply arresting the healing at the phase of cartilage ossification (**Figure 4**). In consequence, the cartilaginous pseudoarthrosis is formed presenting an abundant callus formation, the hypertrophic non-union [53]. It is usually observed in not immobilized fractures, but may also occur in stabilized ones due to implant's destruction (**Figure 5**).

However, rigid fixation precluding movements between bone fragments deprives them of mechanical stimuli that promote osteoblastogenesis [54]. Optimal amplitude of axial movements is below 1 mm, as those are beneficial for osteogenesis, but do not disrupt the blood supply. Other dislocations are detrimental.

It was shown that an excessive distance between bone fragments leads to the cessation of reparative processes leading to non-union [55]. The contact between bone fragments is reduced by a half when translocation reaches 6% of the bone's diameter or five degrees of angulation. Moreover, decreasing cortical thickness that characterizes osteoporotic bone aggravates the loss of interfragmentary contact (**Figure 6a-c**). That leads to the conclusion that fractures require accurate repositioning, especially osteoporotic ones [56].

**Figure 6.** (a) An influence of by-side dislocations between bone fragments on bone contact. (b) An influence of angular dislocations between bone fragments on bone contact. (c) An influence of rotation between bone fragments on bone contact.

**Figure 7.** An inappropriate reduction of the fracture; Lack of the contact between bone fragments and screw situated in-between the fracture gap (arrows) disturb the healing.

compression screws and plates, pre-bending of Arbeitsgemeinschaft für Osteosynthesefragen (AO) plates, intramedullary and external stabilizations and so on [57]. Moreover, it mechani-

(d) months after reoperation. Progressive healing (c3) and satisfactory remodeling (d3) were being observed.

**Figure 9.** Disturbed healing due to an inadequate stabilization of the comminuted fracture of the left radius shaft in 26-yearsold male. The fracture (a1 and a2) was primarily stabilized with the interlocking plate (b1 and b2), but lack of the contact between one of its intermediate fragments precluded the healing. Moreover, mechanical stability was not obtained, as both proximal and distal fragments were stabilized practically with two screws only. The third and the fourth screws situated in-between the fracture gap, were mechanically inefficient and foreclosing the healing; the seventh' was not screwed in at all (b3). Five months later, due to the lack of the progress of the healing (b), the fracture was revised, the fibrous scar was removed and marrow cavity was refreshed, bone fragments were reduced anatomically and stabilized with interlocking plate using four screws for each main fragment. Uneventful healing was observed on X-rays made on the 7th (c) and 12th

**Figure 8.** Schematic representations showing the role of compression of the fracture gap in bone healing.

Fracture Repair: Its Pathomechanism and Disturbances http://dx.doi.org/10.5772/intechopen.76252 15

Interposition of soft tissues or foreign material in-between bone fragments forms the barrier

cally stimulates osteogenesis (**Figure 8**).

that precludes restoration of bone's continuity (**Figure 9**).

To enable healing, the maximal distance between bone fragments should not exceed 1 mm, although the minimal is the best (**Figure 7**). Compression, shortening the distance between bone fragments, is nowadays implemented under several treatment modalities including

**Figure 8.** Schematic representations showing the role of compression of the fracture gap in bone healing.

**Figure 9.** Disturbed healing due to an inadequate stabilization of the comminuted fracture of the left radius shaft in 26-yearsold male. The fracture (a1 and a2) was primarily stabilized with the interlocking plate (b1 and b2), but lack of the contact between one of its intermediate fragments precluded the healing. Moreover, mechanical stability was not obtained, as both proximal and distal fragments were stabilized practically with two screws only. The third and the fourth screws situated in-between the fracture gap, were mechanically inefficient and foreclosing the healing; the seventh' was not screwed in at all (b3). Five months later, due to the lack of the progress of the healing (b), the fracture was revised, the fibrous scar was removed and marrow cavity was refreshed, bone fragments were reduced anatomically and stabilized with interlocking plate using four screws for each main fragment. Uneventful healing was observed on X-rays made on the 7th (c) and 12th (d) months after reoperation. Progressive healing (c3) and satisfactory remodeling (d3) were being observed.

compression screws and plates, pre-bending of Arbeitsgemeinschaft für Osteosynthesefragen (AO) plates, intramedullary and external stabilizations and so on [57]. Moreover, it mechanically stimulates osteogenesis (**Figure 8**).

To enable healing, the maximal distance between bone fragments should not exceed 1 mm, although the minimal is the best (**Figure 7**). Compression, shortening the distance between bone fragments, is nowadays implemented under several treatment modalities including

**Figure 7.** An inappropriate reduction of the fracture; Lack of the contact between bone fragments and screw situated

in-between the fracture gap (arrows) disturb the healing.

**Figure 6.** (a) An influence of by-side dislocations between bone fragments on bone contact. (b) An influence of angular dislocations between bone fragments on bone contact. (c) An influence of rotation between bone fragments on bone

contact.

14 Trauma Surgery

Interposition of soft tissues or foreign material in-between bone fragments forms the barrier that precludes restoration of bone's continuity (**Figure 9**).
