Chapter 9: Autogenous Bone Graft · Bone Healing & Grafting CME

9.1 Introduction

Fresh autograft is the only graft material, apart from vascularized bone, that has living bone-forming cells. An autograft is bone moved from one site to another in the same patient. In this chapter the bone is moved without its blood supply.

A non-vascularized graft has no blood supply after transfer. Most of its cells die. It must be revascularized from the recipient bed. So the result depends on the quality of the bed.

These are the commonest bone grafts in plastic surgery: alveolar bone graft in cleft, orbital floor repair, nasal dorsum reconstruction and bone grafting of facial fractures.

Flowchart: Overview of autogenous bone graft

Autogenous bone graft (non-vascularized)
- Cancellous
  - Fast revascularizationfully replaced by new bone
    - Used for bone healingalveolar cleft, nonunion
      - Donoriliac crest, tibia, distal radius
- Cortical
  - Creeping substitutionslow; weak at 2 to 6 months
    - Used for shape and supportorbit, nasal dorsum, skull
      - Donorcalvarium, rib
- Corticocancellous
  - Both propertiesiliac crest block

9.2 Types of autograft: cancellous and cortical

There are two basic types. They are used for different purposes.

	Cancellous graft	Cortical graft
Structure	Porous, with marrow; large surface area	Dense, compact
Living cells	Many on the surface; some survive	Few; most die
Strength at the time of grafting	None	Strong
Revascularization	Fast (days to weeks)	Slow (months)
Final result	Completely replaced by new bone	Never completely replaced; a mixture of dead graft and new bone
Used when we need	Bone healing and filling: alveolar cleft, nonunion, contained defects	Shape and support: orbital floor, nasal dorsum, cranial defects, strut grafts

A corticocancellous graft has both, for example a block from the iliac crest.

9.3 How a graft incorporates

Incorporation is the process by which the graft is joined to and replaced by the patient's living bone. The two types incorporate differently.

Cancellous graft: vessels grow quickly into the spaces. Osteoblasts first lay new bone on top of the dead trabeculae. Later the dead trabeculae are removed. Formation comes first, so the graft gets stronger from the start.
Cortical graft: vessels cannot enter dense bone. Osteoclasts must first cut tunnels into the graft. Then osteoblasts fill the tunnels. Resorption comes first, so the graft becomes weaker for several months before it recovers. This slow process is called creeping substitution.

Flowchart: Incorporation of cancellous graft

Graft placedsurface cells survive by diffusion
Vessels grow indays to weeks
New bone formed on dead trabeculae
Dead trabeculae resorbed
Fully replaced

Flowchart: Incorporation of cortical graft (creeping substitution)

Graft placedmost cells die
Osteoclasts cut tunnelsgraft becomes weaker
Vessels enter the tunnels
Osteoblasts fill tunnels with new bone
Mixture of new bone and dead graft

Time after grafting	Cancellous graft	Cortical graft
First week	Surface cells survive by diffusion; inflammation	Most cells die; graft is as strong as normal bone
2 weeks to 2 months	Vessels have grown through the graft; new bone is laid on the dead trabeculae; X-ray density increases	Osteoclasts start cutting tunnels from the surface and ends; graft starts to weaken
2 to 6 months	Dead trabeculae are being removed; graft is gaining strength	Weakest period: the graft is porous and can lose up to about half its strength
6 to 12 months	Remodeled to normal bone; graft fully replaced	New osteons fill the tunnels; strength returns
After 1 to 2 years	Normal bone	Strong, but still a mixture of new bone and dead graft

(Enneking 1975; Burchardt 1983)

What this means in practice. A cortical graft is weakest at about 2 to 6 months after surgery. A structural cortical graft must be protected by fixation during this time.

9.4 Graft volume in the face: which bone keeps its shape?

In the face and skull, autografts are used in two main ways. Some fill a gap, such as an alveolar cleft or a small defect after trauma or tumor surgery. Others are placed on the surface of the bone to restore contour, for example on the orbital rim, the cheek or the nose. Large defects after cancer resection usually need vascularized bone instead. For a graft used for contour, the main problem is not nonunion. It is loss of volume with time.

Three things decide how much volume a graft keeps:

Structure: cortical bone keeps more volume than cancellous bone.
Position: an inlay graft keeps more volume than an onlay graft.
Fixation and soft tissue cover: a graft that is fixed rigidly, under healthy soft tissue, keeps more volume.

The embryological origin of the bone (membranous or endochondral) was once thought to be a fourth factor. The next section explains why it is not.

9.4.1 Why calvarial bone is preferred for onlay grafts

Surgeons noticed that calvarial grafts on the face kept their volume better than grafts from the iliac crest or rib. Two explanations were proposed, one after the other.

	First explanation (1983): the origin of the bone	Later explanation (1998): the structure of the bone
Idea	Calvarium is membranous bone. Iliac crest and rib are endochondral bone. Membranous bone was thought to behave differently because of its origin, for example by being revascularized earlier.	Calvarium is mostly cortical bone. Iliac crest is mostly cancellous bone. Cortical bone keeps its volume better, whatever its origin.
Study	Zins and Whitaker compared membranous grafts with endochondral grafts. Volume lost: in rabbits 20% and 65%; in monkeys 17% and 88%. Membranous grafts were also revascularized earlier (Kusiak 1985).	Ozaki and Buchman separated the two factors. They compared cortical membranous, cortical endochondral and cancellous endochondral grafts. The two cortical grafts lost the same volume. The cancellous graft lost the most.
Weakness	The membranous graft was also the cortical graft. The study could not tell which factor caused the difference.	Animal study; but it answered the question the first study could not

Current understanding. What matters is whether the graft is cortical or cancellous, not whether it is membranous or endochondral (Ozaki and Buchman 1998). The calvarium is still the usual first choice for an onlay graft, but for practical reasons: it gives cortical bone of the right thickness, it is often in the same operative field, and the scar is hidden in the hair.

9.4.2 Inlay and onlay grafts

Grafts of the same type kept more volume as inlay grafts than as onlay grafts, at every time point (Sugg 2013).

	Inlay graft	Onlay graft
Where it lies	Inside a defect, with host bone on several sides	On the surface of a bone
Contact with host bone	On several sides, so vessels and cells enter from several sides	On one side only
Load	Carries load as part of the skeleton, so it is maintained	Carries little load, so it is resorbed
Soft tissue	Little pressure on it	Pressed on by the overlying skin and muscle
Examples	Alveolar cleft, gap after an osteotomy	Augmentation of the cheek, chin, nasal dorsum or forehead

9.4.3 Choosing the graft

Flowchart: Choosing the type of graft in the face

What is the graft for?
- To add contour (onlay)
  - Volume must be kept
    - Cortical graftcalvarium, outer table; fixed with a screw
- To fill a gap (inlay)
  - Bone must form quickly
    - Cancellous graftiliac crest; packed firmly, covered with healthy soft tissue
- To support a thin wall
  - Shape and stiffness
    - Thin cortical graftsplit calvarium or rib, for the orbital floor or nasal dorsum

Practical rules for onlay grafts in the face. Use cortical bone. Fix it rigidly, usually with a lag screw. Place it in contact with a bleeding bone surface, under well-vascularized soft tissue. Expect some loss of volume, more where the overlying soft tissue is tight or mobile (Oppenheimer 2008).

9.5 Requirements of the recipient bed

Because a non-vascularized graft depends on the bed, the bed must be prepared properly:

Blood supply: bleeding bone surface under the graft, and well-vascularized soft tissue over it.
Contact: wide contact between graft and host bone, with no dead space.
Rigid fixation: Phillips and Rahn (1988) placed onlay grafts on sheep mandibles, with and without lag screw fixation. Fixed grafts kept more volume (86% for fixed skull grafts) and revascularized faster. A graft that moves resorbs.
Soft tissue cover: closed without tension. An exposed graft is usually lost.
No infection, no radiation. In an irradiated bed, use vascularized bone.

Handling: keep the graft moist (in blood or saline-soaked gauze) and place it without delay. Do not let it dry.

9.6 Donor sites

The donor site is chosen according to the type and amount of bone needed.

Donor site	Type of bone	Main uses	Main risks
Calvarium (parietal)	Cortical (membranous)	Orbit, nasal dorsum, zygoma, forehead, cranial defects	Inner table breach, dural tear, bleeding
Iliac crest (anterior; posterior for more volume)	Cancellous and corticocancellous	Alveolar cleft, nonunion, mandibular defects, interpositional grafts	Pain, hematoma, lateral femoral cutaneous nerve injury, hernia
Rib	Cortical; with cartilage as costochondral graft	Skull defects in children; mandibular condyle and ramus	Pleural tear; unpredictable growth of costochondral graft
Proximal tibia	Cancellous	Alveolar and sinus grafting; small nonunions	Fracture (rare); avoid the growth plate in children
Distal radius, olecranon	Cancellous, small volume	Hand: scaphoid and phalangeal nonunion	Small volume
Mandibular symphysis and ramus	Cortical and corticocancellous, small	Alveolar ridge, small facial defects	Mental nerve and tooth root injury

(Tessier 1982; Younger and Chapman 1989)

9.6.1 Calvarial bone graft

Calvarial bone is the first choice for the face: it is cortical, it is in the same operative field, and the scar is hidden in the hair. The skull has three layers: outer table, diploë and inner table. The graft is taken by splitting through the diploë.

Figure 9.3. Split calvarial graft.

Site: parietal bone, behind the coronal suture and away from the midline (to avoid the sagittal sinus). The parietal bone is the thickest.
In situ split: the outer table is lifted off, leaving the inner table. Possible in adults, who have a diploë.
Ex vivo split: a full-thickness piece is removed, split on the table, and the inner table is put back. Used in young children, who do not yet have a diploë.
Risks: breach of the inner table, dural tear, bleeding. Tessier and colleagues (2005) described the technique and complications from a combined experience of 9,650 cases.

Anatomy for safe harvest: the adult parietal bone is on average about 6 to 7 mm thick, but it varies widely, and CT is useful before harvest. The bone is thin in the temporal region and at the sutures. Harvest stays at least 1.5 to 2 cm from the midline to avoid the sagittal sinus and its lateral lakes. A reliable diploë is usually present from later childhood.

Split calvarial bone graft used to reconstruct the frontal sinus wall — **Split calvarial graft in practice.** A young man with an osteoma of the frontal sinus (A to D). After the tumor is removed, the front wall of the sinus is rebuilt with a split calvarial graft taken from the same exposure and held with resorbable plates (E to G). Result (H). Brown et al., Case Rep Plast Surg Hand Surg 2026, CC BY 4.0.

9.6.2 Iliac crest graft

The iliac crest is the main source of cancellous bone. Complications are donor site pain, hematoma, injury to the lateral femoral cutaneous nerve and contour defect. In children the cartilage cap of the crest is preserved.

Anterior crest: incision placed below or behind the crest, starting at least 2 to 3 cm behind the anterior superior iliac spine. This protects the lateral femoral cutaneous nerve and the inguinal ligament and sartorius attachments, and avoids avulsion fracture of the spine. Cancellous bone is taken through a cortical window or "trapdoor", or by trephine.
Posterior crest: gives about twice the volume of the anterior crest. The patient must be prone. At risk: superior cluneal nerves, sciatic notch and superior gluteal artery, sacroiliac joint.
Complications: in 243 grafts, major complications occurred in 8.6% and minor in 20.6% (Younger and Chapman 1989). The commonest long-term problem is donor site pain. Others: hematoma, seroma, infection, meralgia paresthetica, gait disturbance, fracture of the ilium, hernia through a full-thickness defect, contour deformity.

Harvest of a corticocancellous block from the anterior iliac crest — **Harvest from the anterior iliac crest.** (a) The inner surface of the crest is exposed. (b to d) A cortical block is outlined and cut with a fine saw and osteotome. (e) Cancellous bone is then curetted from the bed. (f) The block is trimmed on the back table. Raafat, Omara and Mounir, Clin Oral Investig 2025, CC BY 4.0.

Model of the ilium showing where the graft is taken in relation to the anterior superior iliac spine — **Where to cut on the iliac crest.** Models of the right ilium. 1 = anterior superior iliac spine. The rectangles show graft sites at different distances behind the spine. A harvest too close to the spine leaves a thin bridge of bone that can break. Schmitz et al., J Orthop Surg Res 2018, CC BY 4.0.

Radiograph of a fracture of the anterior superior iliac spine after graft harvest — **A donor site complication.** (a) Fatigue fracture of the anterior superior iliac spine (arrow) after bone was harvested from the crest just behind it. (b) The fracture needed fixation. This is why the harvest starts at least 2 to 3 cm behind the spine. Schmitz et al., J Orthop Surg Res 2018, CC BY 4.0.

9.6.3 Rib and costochondral graft

Harvested subperiosteally, usually the 5th to 7th rib, through an inframammary incision. Check for a pleural tear with a Valsalva maneuver under saline.
Split rib is used for skull defects in children. The rib regenerates if the periosteum is kept.
Costochondral graft: rib with a 2 to 3 mm cap of cartilage, used to reconstruct the mandibular condyle and ramus in children (hemifacial microsomia, TMJ ankylosis). It has growth potential, but growth is unpredictable, and overgrowth can occur.

**Harvest of a costochondral graft.** (A) Incision marked over the rib. (B) The rib is exposed under its periosteum. (C) The rib is lifted and divided. (D) The graft, with its cap of cartilage at one end. Bhardwaj et al., Cureus 2024, CC BY.

9.6.4 Instruments used to harvest and prepare the graft

The instrument decides the form of the graft: block, chips or fine particles. It also affects how many cells survive. Heat from a fast burr kills osteocytes, so sharp hand instruments, low-speed drills with irrigation and piezoelectric saws are preferred.

Instrument	What it does	Typical use
Osteotome, gouge and curette	Lift a cortical window or block, then scoop cancellous bone	Iliac crest, calvarium, tibia
Trephine	A hollow drill that removes a core of cancellous bone through a small incision	Iliac crest for alveolar bone graft; chin; tibia
Piezoelectric saw	Cuts bone by ultrasonic vibration. It does not cut soft tissue, so nerves, dura and sinus lining are safer.	Block grafts from the ramus and chin; calvarial and orbital osteotomies
Bone scraper	A blade drawn over the cortex collects thin shavings in a chamber	Small volumes of particulate graft in the face and mouth
Bone mill	Grinds blocks or spare bone into particles of even size	Turning cortical or corticocancellous bone into packable graft; also used for resected bone that would be discarded
Reamer-irrigator-aspirator (RIA)	A reamer passed down the medullary canal of the femur or tibia, with continuous irrigation and suction. The reamings are caught in a filter.	Large volumes of cancellous-type graft for long bone defects, including the second stage of the induced membrane technique

Piezoelectric cuts for a block graft, the split block, and a bone scraper — **Piezoelectric saw and bone scraper.** a: thin cuts made with a piezoelectric saw outline a block graft on the mandible. b: bone shavings collected in a bone scraper. c: the block split into two thin plates. Saleh et al., BMC Oral Health 2026, Fig. 2, CC BY 4.0.

Bone placed in a bone mill — **Bone mill.** A piece of bone is placed in the mill (left). Turning the handle (right) grinds it into particles for packing. Park et al., J Clin Med 2025, Fig. 4, CC BY 4.0.

Reamer-irrigator-aspirator in use and the bone collected in its filter — **Reamer-irrigator-aspirator.** a: the reamer is passed into the medullary canal through a small incision at the knee; reamings and irrigation fluid drain into the collection canister. b: the filter full of bone. c to e: the harvested graft. Fischer et al., Life 2025, Fig. 2, CC BY 4.0.

RIA autograft, freeze-dried allograft granules and the two mixed — **Autograft extended with allograft.** a: autograft harvested with the RIA. b: freeze-dried cancellous allograft granules from donor femoral heads. c: the two mixed. d to g: use in a hindfoot fusion over a nail. When autograft volume is not enough, it is commonly extended in this way. Hückstädt et al., Eur J Trauma Emerg Surg 2026, Fig. 1, CC BY 4.0.

Examples of products used with autograft.

Purpose	Product	Company
Harvest from the medullary canal	Reamer-Irrigator-Aspirator (RIA)	DePuy Synthes
Bone scraper for thin cortical shavings	SafeScraper	Meta
Piezoelectric bone saw	Piezosurgery	Mectron
Holding particulate graft together	Fibrin sealant, for example Tisseel	Baxter
Stopping bleeding from the cut bone	Bone wax; Ostene (a water-soluble substitute that does not block bone healing)	Several; Baxter
Fixing an onlay graft in a child	Resorbable plates and screws: LactoSorb, RapidSorb, SonicWeld Rx	Zimmer Biomet; DePuy Synthes; KLS Martin

9.7 Alveolar bone graft

The alveolar bone graft is the commonest use of iliac cancellous graft in our specialty, so it is described here in detail.

Aims: to give a continuous dental arch, to give bone for the canine to erupt into, to close the oronasal fistula, to support the alar base, and to give bone for a dental implant if needed.

Why cancellous bone: the graft must be completely replaced by normal bone so that a tooth can erupt through it and be moved orthodontically. Cortical bone would not allow this.

Timing is classified by age:

Type	Age	Comment
Primary	Under 2 years	Mostly abandoned: it restricts maxillary growth.
Early secondary	2 to 5 years	Used in some centers.
Secondary	9 to 11 years (mixed dentition)	Standard. Done before the canine erupts, when its root is about half to two-thirds formed.
Late secondary	After canine eruption	Poorer results.

Evidence: Bergland (1986) reported 378 patients. The best results were when the graft was done at 9 to 11 years, before canine eruption: 64% achieved normal bone height between the teeth. The erupting tooth loads the graft, and loaded bone is maintained.

9.7.1 Technique

Flowchart: Steps of secondary alveolar bone grafting

Orthodontic expansion of the arch
Gingival mucoperiosteal flaps raised
Nasal floor and palatal lining closedwatertight
Cancellous iliac bone packed
Flaps advanced and closed without tension

Drawings of the steps of alveolar cleft closure with gum flaps — **The soft tissue steps (drawings).** (A) The cleft and bone defect. (B) Incision along the cleft margins. (C) The gum flap is raised. (D) The palatal flap is raised and the nasal floor is closed. (E to G) The pocket is filled and the gum flaps are closed over it. Chu et al., J Clin Med 2020, CC BY 4.0.

Alveolar cleft grafted with cancellous bone from the iliac crest — **Alveolar bone grafting with cancellous iliac bone.** (a) The cleft. (b) Flaps raised and cleft exposed. (c) The iliac donor site. (d) The pocket packed firmly with cancellous bone. (e) Closure without tension. Raafat, Omara and Mounir, Clin Oral Investig 2025, CC BY 4.0.

Alveolar cleft grafted with two cortical blocks and cancellous bone between them — **A variation for a wide cleft.** Two thin corticocancellous blocks from the iliac crest are fixed with screws on the front and palatal sides of the cleft (c, d), and cancellous bone is packed between them (e). The blocks hold the shape while the cancellous bone is incorporated. Raafat, Omara and Mounir, Clin Oral Investig 2025, CC BY 4.0.

9.7.2 Assessment of the result

Bergland type	Height of the bone between the teeth
I	Normal height
II	At least three-quarters of normal
III	Less than three-quarters of normal
IV	Failure: no continuous bony bridge

Types I and II are counted as success. CT (cone beam) measures the volume more accurately than the plain radiographs used in the Bergland scale.

Diagram of the Bergland scale and three-dimensional assessment of an alveolar bone graft — **Assessing the result.** (A) The Bergland scale: type I to IV by the height of the bone bridge between the teeth. (B) A more detailed radiographic scale. (C) Three-dimensional assessment from cone beam CT, which measures the volume of bone in the cleft. Erkert et al., Sci Rep 2025, CC BY 4.0.

9.7.3 Factors that affect success

Timing before canine eruption (the most important factor).
Watertight closure of the nasal lining and tension-free gingival flap cover.
Good oral hygiene and no active infection.
Width of the cleft; bilateral clefts do worse than unilateral.

9.7.4 Alternatives to iliac crest

Tibia, mandibular symphysis and calvarium have been used; they give less cancellous bone. rhBMP-2 has been studied to avoid a donor site, mainly in skeletally mature patients, and is off-label.

9.8 Limits of non-vascularized graft: the mandible

The sections above show where non-vascularized graft works well. This section shows where it starts to fail. The best evidence is from segmental defects of the mandible.

Study	Non-vascularized graft	Vascularized bone flap
Pogrel 1997 (68 patients)	76% success (22 of 29)	95% success (37 of 39)
Foster 1999 (75 patients)	69% bony union (18 of 26)	96% bony union (47 of 49)

In Pogrel's study, failure of non-vascularized grafts increased with the length of the defect. This is the source of the commonly quoted limit of about 6 cm.
In Foster's study the vascularized group did better even though it had more irradiated patients (45% versus 11%).

Flowchart: Segmental mandibular defect: graft or flap?

Segmental mandibular defect
- Short (under about 6 cm), lateral, clean bed, no radiotherapy
  - Non-vascularized graft possibleunion about 70 to 75%
- Long, anterior, irradiated, contaminated, or implants planned
  - Vascularized bone flapunion about 95%

Summary. A non-vascularized graft is acceptable for a short lateral mandibular defect in a clean, non-irradiated bed. For a long defect, an anterior defect, an irradiated or contaminated bed, or when dental implants are planned, vascularized bone is needed.

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