**7. Bone grafting with extra oral donor sites**

#### **7.1. Iliac crest**

The iliac crestal bone is the most common extra-oral donor site for bone grafts. It may be harvested vascularized, non-vascularized, cortical, cancellous or corticocancellous in different shapes and in large sizes (Figure 7).

**Figure 7.** Iliac bone graft harvested to reconstruct the mandible.

The location of the iliac crest permits the surgeons to harvest bone graft and operate simulta‐ neously to save operating time. A full-thickness iliac crest bone graft consists of two thick cortices with sufficient amount of cancellous bone in between and can restore the thickness and height of mandibular bone efficiently. The graft shows a good success rate, and dental implant insertion is possible in this type of bone graft [19, 20]. Mandibular continuity defects treated with free iliac bone grafting are documented with about a 70% success rate [21]. The rate of successful union is decreased significantly where the defect is longer than 6 cm [21, 22]. The posterior iliac crest also can be used as a donor site. Morbidity rate for anterior iliac crest bone grafts is more than posterior iliac site (23% and 2% respectively) [23].

**Complications.** Postoperative pain, iliac fractures, gate disturbances, hematoma, herniation of abdominal contents, vascular injury, nerve injury, unsightly contour defects along the iliac crest and growth disturbances in young ages [24].

### **7.2. Calvarial graft**

The calvarium is a popular cortical bone grafting site basically for its mechanical features and very slow resorption rate [24]. It is suggested for facial augmentation, orbital roof and floor reconstruction, and covering midface defects rather than alveolar defects. Typically, the outer cortex is used as a cortical plate graft (Figure 8), although a full-thickness or inner cortex graft may be used.

The skull growth continues to the age of 8 and become thicker until the age of 20 years. The thickest portion is located at the parietal region. This donor site can provide 8 by 10 cm of bone [25]. Thickness of the calvarial bone is highly variable so preoperative radiographs help the surgeon to harvest bone safely [25]. It should keep in mind that dura is tightly adherent to the inner cortex and can easily be injured if the inner cortex is aimed to be harvested. Also various vascular structures are located just under the bone at different sites, like the superior sagittal sinus in the midline. The inner and outer cortices may merge together in inferior and lateral portions. Other anatomic structures, such as transcortical emissary veins, subcortical vessels,

**Figure 8.** Calvarial bone graft harvesting approach. A, The scalp is retracted and calvarium is exposed. B, The osteoto‐ my site is visible.

and aberrant arachnoid plexuses are also at risk and should be considered in the surgical procedures [25]. Temproparietal regions can be used to harvest more curved grafts and straight grafts can be harvested from occipital or frontal regions.

**Complications.** Contour deformity at the donor site and grafting bone fracture in harvesting are the most common complications. Dural exposure or rupture is another complication but is not common. Intracranial hemorrhage due to this type of graft harvesting has been reported.

#### **7.3. Tibial graft**

**Figure 7.** Iliac bone graft harvested to reconstruct the mandible.

520 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

crest and growth disturbances in young ages [24].

**7.2. Calvarial graft**

may be used.

The location of the iliac crest permits the surgeons to harvest bone graft and operate simulta‐ neously to save operating time. A full-thickness iliac crest bone graft consists of two thick cortices with sufficient amount of cancellous bone in between and can restore the thickness and height of mandibular bone efficiently. The graft shows a good success rate, and dental implant insertion is possible in this type of bone graft [19, 20]. Mandibular continuity defects treated with free iliac bone grafting are documented with about a 70% success rate [21]. The rate of successful union is decreased significantly where the defect is longer than 6 cm [21, 22]. The posterior iliac crest also can be used as a donor site. Morbidity rate for anterior iliac

**Complications.** Postoperative pain, iliac fractures, gate disturbances, hematoma, herniation of abdominal contents, vascular injury, nerve injury, unsightly contour defects along the iliac

The calvarium is a popular cortical bone grafting site basically for its mechanical features and very slow resorption rate [24]. It is suggested for facial augmentation, orbital roof and floor reconstruction, and covering midface defects rather than alveolar defects. Typically, the outer cortex is used as a cortical plate graft (Figure 8), although a full-thickness or inner cortex graft

The skull growth continues to the age of 8 and become thicker until the age of 20 years. The thickest portion is located at the parietal region. This donor site can provide 8 by 10 cm of bone [25]. Thickness of the calvarial bone is highly variable so preoperative radiographs help the surgeon to harvest bone safely [25]. It should keep in mind that dura is tightly adherent to the inner cortex and can easily be injured if the inner cortex is aimed to be harvested. Also various vascular structures are located just under the bone at different sites, like the superior sagittal sinus in the midline. The inner and outer cortices may merge together in inferior and lateral portions. Other anatomic structures, such as transcortical emissary veins, subcortical vessels,

crest bone grafts is more than posterior iliac site (23% and 2% respectively) [23].

The anterior surface of the tibial plateau is mentioned as a donor site for cortical or cortico‐ cancellous bone grafts. Proper mechanical features of the tibial cortex seem to be useful in augmentation of atrophic alveolar ridges for implant insertion or facial bone defect recon‐ struction. Up to 40 cc cancellous bone can be harvested from the tibia (Figure 9).

**Figure 9.** Tibial bone graft harvesting approach. A, the donor site is indicated before making the incision. B, the flap is retracted and bone graft is harvested using a curette.

The most common approach for this purpose is laterally at Gerdy's tubercle [26].

## **7.4. Rib graft**

Free rib bone was one of the first autogenous bone grafts used for reconstruction of mandibular defects. Osseous or osseochondral grafts can be harvested from fifth to seventh ribs. Although costochondral grafts remain popular for the treatment of mandibular ramus and condylar defects, the quality and quantity of rib bone make it less popular for jaw defect reconstruction nowadays [27].

**Complications.** Postoperative chest wall pain, pleural injury leading to pneumothorax, and overgrowth of the graft [27, 28].
