1 Bone grafts, bone flaps, bone replacement materials and techniques

10.1055/b-0040-178439

1 Bone grafts, bone flaps, bone replacement materials and techniques

1.1 Types and harvest of bone grafts and bone flaps

Michael Ehrenfeld, Christine Hagenmaier, Remy H Blanchaert Jr

1 Introduction

In craniomaxillofacial (CMF) surgery bone grafts and bone flaps are used to replace missing bone. Bone deficits or defects may result from congenital malformations and developmental disorders, or originate from tumor surgery, trauma, medication-related bone diseases, irradiation or infections. Bone grafts may also be indicated in esthetic surgery.

Today fresh autogenous bone is still the gold standard among all available bone replacement materials [Axhausen, 1962; Schweiberer, 1970; Tessier et al, 2005]. However, nonresorbable alloplastic materials (eg, porous polyethylene, silastic, ceramic materials) are preferred for contour augmentation procedures because they do not undergo the unpredictable initial remodeling and resorption seen with nonvascularized autogenous bone grafts. Bone graft harvest itself may be associated with complications and undesired adverse effects [Tessier et al, 2005].

Fresh autogenous bone in principle can be harvested as nonvascularized bone grafts, pedicled bone grafts, and microvascular bone flaps [Bardenheuer, 1892; Sykoff, 1900; Krause, 1907; Axhausen, 1908; Lexer, 1908; Rydygier, 1908; Lindemann, 1916; Matti, 1932; Converse, 1945; Conley, 1972; Boyne, 1973; Taylor et al, 1975; O’Brien, 1977; Taylor et al, 1979; Quillen, 1979; Ariyan, 1980; Swartz et al, 1986]. Pedicled bone grafts today are rarely used in CMF reconstructive surgery; thus they are not further discussed in this chapter. Nonvascularized autogenous bone can be harvested as cancellous bone and marrow, cortical bone, corticocancellous bone, and so-called bone dust, which is small particles of cortical bone.

In the preoperative planning phase, the surgeon must assess the patient carefully to determine the needed type of bone based on the characteristics of the defect, the quality and quantity of the surrounding soft tissues, and the specific clinical indication for surgery. Potential donor sites must then be considered and a surgical plan developed that balances the risk-benefit ratio of each of the suitable donor sites and graft/flap types. This chapter reviews the most commonly used bone graft and bone flap donor sites used in CMF reconstruction. The intent is to provide the surgeon with a review of the potential donor sites and an outline of the techniques used for bone graft/flap harvest and donor site management.

2 Nonvascularized bone grafts

Nonvascularized bone grafts are typically harvested from certain preferred donor sites. In the recipient site the bone must be revitalized mainly via tissue ingrowth. Therefore, the recipient site must be of good biological quality, especially well perfused, and allow for complete 360° coverage of the bone graft(s) to avoid exposure, contamination, and healing disturbances [Axhausen, 1962; Schweiberer, 1970; Axhausen, 1951; Axhausen, 1952; Chalmers, 1959; Williams, 1962; Heiple et al,1963; Ray, et al, 1963; Burwell, 1965]. Revitalization of a nonvascularized bone graft goes along with a process of resorption, remodeling, and maturation, which is typically associated with a loss of bone volume. The amount of resorption depends on many factors, such as the dimensions and the density of the grafted material (it takes longer to revitalize large and more dense bone grafts, and therefore they show a greater percentage of bone loss), the type of the bone (cortical, cancellous, corticocancellous, bone dust), tissue qualities at the recipient site (vascularization), biomechanical properties (functional loading), and fixation of the bone graft to surrounding bone [Lexer, 1908; Lentrodt et al, 1976; Eitel et al, 1980; Schweiberer et al, 1981; Lentrodt et al, 1987]. The amount of bone loss after nonvascularized bone transplantation is unpredictable.

Indications for nonvascularized bone grafts

Nonvascularized bone grafts are indicated for filling bone defects, for example, after extirpation of large cysts (see chapter 2.3). Another widespread indication is for ridge augmentation procedures in preprosthetic surgery and dental implantology (see chapter 4.4). Small mandibular or maxillary continuity defects can be treated with nonvascularized bone grafts; other indications include osteotomy gaps in orthognathic surgery, defect zones in fractures, and facial clefts (see chapters 4.6 and 4.7) [Steinhäuser, 1968]. Nonvascularized bone grafts have been used for augmentation procedures in esthetic surgery (malar augmentation, chin augmentation), but because of the potential loss of bone volume nonresorbable grafting materials like ceramic implants or porous polyethylene should be considered instead [Reuther, 1979; Bell, 1992].

2.1 Cancellous bone and marrow

Cancellous bone and marrow is commonly used in CMF reconstruction of small defect areas. It may be harvested from either the ilium or tibia using a trocar, when only small amounts of bone graft are needed, or via open techniques. Grafts obtained by trocar may be suitable for small defects, such as in a fracture nonunion or for sinus floor elevation procedures. Harvest of the bone graft is generally simple; however, proper selection of the most appropriate donor site and careful execution of the harvest are required to minimize donor site morbidity and potential complications. Recipient site preparation for cancellous grafting is perhaps more critical. Development of a well-vascularized, appropriately sized pocket of soft tissue is critical to containment of the graft and a prerequisite for revascularization. Avoidance of oral exposure and therefore bacterial contamination is also vital. Grafted sites, which require extensive softtissue dissection and creation of potential dead space, should be drained with a closed suction technique to avoid hematoma and seroma formation. Perioperative antibiotics are administered in the standard fashion. Compressed cancellous bone and marrow can be handled nicely and can be shaped and molded to achieve anatomically adequate filling of appropriate defects.

This chapter outlines the most commonly used donor sites for maxillofacial bone graft reconstruction, which are the ilium and tibia. General characteristics of each site are described. A description of open harvesting techniques for the anterior and posterior ilium and the tibia are provided in the subsequent sections of this chapter.

2.1.1 Ilium

The ilium is a common donor site for autogenous cancellous bone used in CMF reconstruction. Bone can be harvested from either the anterior or posterior ilium. The anterior site is most often used because of its ease of access in comparison with the posterior ilium that requires the patient to be placed in a prone position. However, when large amounts of cancellous bone (> 35 cc compressed) are required, the posterior ilium is a more suitable donor site and a viable alternative to bilateral anterior harvests. The character of the bone is different from these two locations, which is, however, more important for the harvest of corticocancellous grafts. Major CMF reconstruction procedures typically require open techniques for harvest of appropriate and adequate amounts of bone. The posterior ilium provides a thin monocortical element and cancellous material, which often contains visible fat in adult patients. The anterior ilium may be harvested as either cancellous bone and marrow, or as a monocortical or bicortical graft. It has a much thicker cortical component and a less fatty appearing cancellous bone and marrow component.

2.1.1.1 Ilium—anterior technique (medial harvest)

The patient is positioned supine. In some cases, a folded sheet under the ipsilateral hip may make medial visualization easier. The ilium should be outlined on the skin with a surgical marker from the anterior superior iliac spine (ASIS) to the iliac tubercle. The site should be widely prepared and draped. The length of the incision depends on the volume of the harvest required. In general, a 2–6 cm incision is made parallel to the iliac crest either over or slightly lateral to the crest ( Fig 1.1-1 ).

Fig 1.1-1 Approach to the anterior ilium.

The incision should be no closer than 1 cm to the ASIS to minimize injury to the lateral cutaneous femoral nerve. Incision is made through the skin and subcutaneous tissue, then through Scarpa fascia. Dissection is continued to the aponeurosis overlying the iliac crest ( Fig 1.1-2 ).

Fig 1.1-2 After incision of the skin and subcutaneous tissue, the fascia is exposed.

Being careful to incise the aponeurosis minimizes bleeding and facilitates reapproximation. Careful subperiosteal dissection allows excellent exposure. Avoid overzealous softtissue retraction, as this is the likely cause of injury to the lateral femoral cutaneous nerve. For the harvest of cancellous material only, the crest may be split with chisels and the cancellous material removed with gouges and/or curettes ( Fig 1.1-3 ).

Fig 1.1-3 Harvesting of cancellous bone and marrow with a curette.

In pediatric patients the iliac crest is still covered with cartilage. The cartilage can be easily separated from the bone with a scalpel and reflected medially pedicled on the adjacent soft tissues to allow access to the bone. The collected cancellous bone can be placed in a 30 cc syringe and compressed to better delineate the volume harvested ( Fig 1.1-4 ).

Fig 1.1-4 The cancellous bone graft material has been placed in a 30 cc syringe and compacted.

The syringe can then be placed in a lap sponge moistened with chilled saline solution and set aside. This simplifies the collection of the bone, reveals the actual volume obtained, and facilitates the delivery of the bone to the recipient site. However, it must be noted that cancellous bone and marrow should never be placed in saline solution or similar or washed out with saline solution to avoid loss of cells and proteins.

Placement of a resorbable hemostatic agent in the harvest site often controls hemorrhage such that there is no need for a closed suction drain. The wound is then closed in layers.

2.1.1.2 Ilium—posterior technique

The patient is positioned prone. Extreme care in positioning with placement of appropriate lateral chest support and careful rotation of the arms is important to avoid elevated ventilation pressures and nerve injury. The bed is flexed, and reverse Trendelenburg applied to keep the upper body parallel to the floor ( Fig 1.1-5 ).

Fig 1.1-5 Proper positioning for harvest of bone from the posterior ilium is critical. Note the lateral padding.

The surgical anatomical landmarks are then outlined with a marker to include the iliac crest, sacrum, and the insertion of the gluteus maximus muscle ( Fig 1.1-6 ). Next, the operative field is scrubbed and then prepared and draped excluding the anal region from the field.

Fig 1.1-6 Upper borders, iliac crest, sacrum, and tubercle where musculus gluteus maximus inserts. Incision line (4). 1 = upper border 2 = sacrum 3 = tubercle 4 = incision line

A curvilinear incision inferior to and parallel to the posterior iliac crest is then created. The incision should be placed 1–2 cm lateral to the sacroiliac joint to avoid the cluneal nerve. The dissection is deepened through fascia to the insertion of the gluteus maximus muscle. The periosteum is then incised and elevated exposing a triangular protuberance at the site of the muscle insertion. It is recommended that the location of the sciatic notch be determined by manual palpation to assure that no retractor is placed in its vicinity. A retractor is then placed to facilitate harvest. The lateral iliac cortex is removed with a saw and/or chisel and the underlying cancellous material collected with gouges and/ or curettes ( Fig 1.1-7 ).

Fig 1.1-7 After removal of a portion of the lateral cortex, excellent access to the cancellous bone and marrow is provided.

Avoid violation of the medial cortex and the sacroiliac joint. If pure cancellous bone and marrow are needed, the cortical bone may be replaced and fixed with miniplates. Often times, the application of a resorbable hemostatic agent obviates the need for a closed suction drain. The wound is closed in layers using resorbable sutures.

2.1.2 Tibia

The proximal tibial metaphysis has reemerged in recent years as an alternative site for the harvest of cancellous bone. After description of the harvest procedure and its applications in CMF surgery, the tibia has become an accepted and frequent alternative to the anterior ilium for defects requiring only small amounts of bone. The major reported advantage is decreased morbidity. Reports of tibial bone harvest with local anesthesia and deep sedation demonstrate the simplicity of the procedure and the utility of the technique in CMF surgery. Cancellous harvests of 15–25 mL uncompressed bone have been reported. This volume is perfectly suited for dentoalveolar reconstructions in preparation for implant placement (sinus augmentation, etc) and management of fracture nonunion where only cancellous material is needed [Herford et al, 2003].

2.1.2.1 Harvest technique

Approaches lateral or medial to the patellar tendon are possible. The anatomy of the proximal lower leg should be outlined with a surgical marker to include the insertion of the patellar tendon and the tibial plateau ( Fig 1.1-8 ).

Fig 1.1-8a–b Planning for a lateral bone harvest from the tibial head. The incision line (red) is obliquely orientated to the joint plane and is placed just above and over Gerdy tubercle. P indicates patella; AS, articulation surface, plane of the femoral tibial joint; and F, fibular head.

The incision length depends on the harvest technique. A small stab is required if a trocar is used. Otherwise the incision is carried down to the periosteum which is incised and reflected. A bone window is then created with a sagittal saw or piezotome and removed ( Fig 1.1-9 ).

Fig 1.1-9a–b After osteotomy of the tibial cortex, cancellous bone and marrow can be harvested.

The cancellous bone is harvested with a curette, placed in a small container, and set aside. Operative site hemostasis is facilitated by the placement of a topical hemostatic agent. The wound is then closed in layers. After application of a wound dressing, the leg is covered in a soft roll and a gently compressive elastic bandage is applied. Ambulation is allowed immediately with a rapid return to normal exercise activities in a few weeks.

2.2 Cortical bone

Cortical bone grafts are used in CMF reconstruction for structural support and onlay augmentation. Examples of use of these grafts for structural support include maxillary lengthening with loss of bone contact and for restoration of the pillars of the facial skeleton in high-energy CMF trauma. In orthognathic surgery, cortical bone grafts are often available from the distal portion of the proximal segments after sagittal ramus osteotomies. These bone grafts can be used to augment the maxilla and to bridge gaps after maxillary advancements or maxillary lengthening procedures in bimaxillary cases. Cortical outer table bone grafts from the cranial vault or hip are alternatives, among others. Cortical bone grafts may be used for onlay augmentation in dentoalveolar reconstruction, for instance, after atrophy or traumatic bone loss, to allow placement of osseointegrated implants.

Cortical bone grafts require rigid fixation for optimal results. Whenever possible, a lag screw technique should be used for stabilization of the grafts after appropriate contouring. Miniplate/microplate fixation is an alternative. Failure to fixate the graft can result in migration, movement, infection, and rapid resorption.

2.2.1 Mandible

The harvest of cortical bone from the mandible is used for the purpose of onlay bone grafting in preparation for dental implant placement. The procedure is commonly performed with the patient under local anesthesia or local anesthesia and sedation. Patient acceptance of an oral donor site is high in comparison to a distant donor site.

Cortical bone from the mandible is typically harvested from either the ramus or symphysis ( Fig 1.1-10 ).

Fig 1.1-10 Potential mandibular bone harvest sites.
2.2.1.1 Ramus

The ramus of the mandible is exposed through a standard posterior vestibular access identical to that used for orthognathic surgery. The mucosa is incised along the external oblique line and the soft tissues are reflected by subperiosteal dissection. Thus, a wide exposure is obtained. A small drill bit, a specially designed right-angle rotating saw or a piezotome is used to outline the graft harvest along the lateral portion of the ramus. A small curved chisel allows elevation of the graft. The graft is then immediately placed at the recipient site and rigidly stabilized or placed in a saline moistened sponge and placed aside. The site is thoroughly irrigated and closed in a single layer. A gentle compressive dressing can be placed on the face to assist in closure of the dead space created by the dissection.

2.2.1.2 Symphysis

The symphysis of the mandible is exposed through a standard vestibular access incision. It is important to maintain a suitable cuff of the unattached tissue by placing the incision labial to the junction of the attached and unattached mucosa. The mentalis muscles must be elevated, and the dissection completed widely to obtain adequate exposure. It is often best to dissect circumferentially around the mental nerve and release the periosteum at the mental foramina to avoid traction injury to the mental nerves. The bone harvest is then outlined with either a small fissure bur, a piezotome, or a specially designed rotating saw. Care must be taken to stay a few millimeters below the apices of the teeth. A curved osteotome is required to elevate the bone graft. For wound closure suturing in two layers, ie, muscle and mucosa, is required. Proper support of the mentalis muscles is necessary to achieve an esthetic outcome. If the mentalis muscle is not resuspended, chin ptosis will likely occur. Additional support of the mentalis muscle and closure of the dead space can be provided with tape or compressive dressing support of the chin. It appears that postoperative pain and local wound complications are more common when the symphysis is used to obtain cortical bone from the mandible.

2.2.2 Maxilla

From the maxilla small amounts of mostly cortical bone can be taken from the nasal aperture ( Fig 1.1-11 ) or from the tuber maxillae. The maxilla is approached via transoral incisions in the upper vestibular mucosa.

Fig 1.1-11 Bone harvest from the nasal aper ture.

Other than swelling and pain for a few days, there is no significant donor site morbidity. The bone volume is sufficient for small defects, such as localized ridge augmentations in dental implantology.

2.2.3 Cranial bone

In adult patients the harvest of split thickness calvarium is typically accomplished by removal of the outer cortex; however, the inner cortex may also be separated from a previously elevated full thickness calvarial bone flap as it is commonly performed in craniofacial surgery. The description here will focus on the former technique ( Fig 1.1-12 ). The well-developed diploe allows for easy harvest of the outer table. Donor site morbidity is low with proper technique [Jackson et al, 1986]. Younger children typically do not have a layered skull with outer table, diploe, and inner table. Here, harvest of outer table bone grafts is not possible; however, full thickness cortical bone grafts may be taken and split in two layers. One layer is usually replanted to maintain skull continuity for brain protection.

Fig 1.1-12a–e Outer table calvarial cortical bone grafts are outlined with a rose bur before harvest with a saw and/or chisel (a–b). Chisel is put underneath the outer cortical plate to elevate the bone graft (c). The donor site shows the areas lateral to the harvested grafts where the calvarium was tapered to allow access to the diploic space (d). Harvested outer table cranial bone grafts (e).

Access to the parietal bone is accomplished through either a curvilinear incision directly over the parietal area or by a coronal incision. Dissection widely beneath the galea allows wide exposure with gentle retraction. The planned bone harvest is outlined with a rose burr taking care to completely osteotomize the outer cortex without perforation of the inner cortex.

A saw or chisel is then used in the diploic space to complete the osteotomy. Angled saw blades may further facilitate the bone graft harvest. The cortical bone can be brittle; therefore, it is best to gently elevate the entire bone graft taking care to free the graft evenly. Excessive force on any portion of the graft will result in fracture or create cracks that will fracture while the graft is being stabilized or recontoured. The harvested bone graft should be wrapped in a saline moistened sponge and placed aside or immediately placed into the recipient site and stabilized rigidly. The donor site is closed over a closed suction drain after copious irrigation.

2.2.4 Ilium

The ilium is a rarely used donor site for the harvest of cortical bone only. Clinical conditions (ie, closed head injury), or operator experience may necessitate the use of this site in some instances. Cortical bone harvest from the ilium requires the identical exposure described in section 2.1.1. The most important modification of the technique is the utilization of a saw or piezotome for creation of the osteotomies. The cortex can then be easily removed with a straight or slightly curved chisel. The inner cortex is preferred to avoid deformity. The technique is similar to the one shown in Figs 1.1-1 1.1-13 , but only the cortical bone is harvested. The cancellous bone exposed following removal of the cortical bone will tend to bleed. This technique, therefore, requires extreme attention to hemostasis before donor site closure, a suction drain may be indicated [Hall et al, 1981].

Fig 1.1-13a–b After outlining the desired style and height of a cortico-cancellous graft from the inner aspect of the ilium, the block is elevated with a chisel.
2.3 Corticocancellous bone grafts
2.3.1 Ilium

The exposure for harvest of corticocancellous bone from the ilium is outlined completely in section 2.1.1. In the anterior approach, corticocancellous blocks of bone may be harvested from the inner or outer aspect ( Fig 1.1-13 ).

Bone blocks may be harvested with one or both cortices. The harvest can be performed including parts of the iliac crest or underneath the crest ( Fig 1.1-14 ).

Fig 1.1-14 By taking bicorticocancellous bone from underneath the iliac crest, the outer contour of the iliac crest is preserved.

To routinely assure harvest of a complete corticocancellous block, it is recommended that saws be used. The saw provides a tactile sense of when the opposite cortex is encountered. It is important that the vertical and inferior bone cuts be made with diverging walls to allow easy and gentle elevation of the graft from the donor site. If the inferior cut is made first, hemorrhage will not complicate visualization of the field while the vertical and then superior horizontal cuts are made. The entire corticocancellous block may be transferred directly to the recipient site and stabilized with plate(s) and screws ( Fig 1.1-15 ).

Fig 1.1-15 Stabilization of the bone graft in the chin area with a reconstruction plate. Cancellous bone and marrow may later be used to fill the osteotomy gap.

For segmental mandible reconstruction, a reconstruction plate placed along the lateral surface of the mandible provides stability. Additional cancellous bone and marrow may be placed at the intersection of the graft and native bone as well as into osteotomy gaps to improve contact and assure osseous union.

2.3.2 Rib

The ribs provide a significant donor site for the elective reconstruction of the orbit, calvarium, mandibular condyle, and ramus. For condylar head reconstruction, a costochondral graft, which is a variation of a rib graft, is indicated. In this setting a composite graft with a 5 mm cartilage cap is harvested. The perichondrium must be maintained on the junction of the bone graft and cartilage to provide stability to the cartilage cap/rib construct.

Some avoid the rib donor site in the setting of trauma because of concerns regarding postoperative splinting and less effective ventilation or atelectasis. Harvest of the 4th–6th rib is common. The shape of the ribs in this region is most suitable. Whenever possible, the opposite side rib should be used for mandible reconstruction to take full advantage of the natural curvature of the rib.

Harvest of the rib is completed with the patient in supine position. A small folded towel underneath the donor site is of assistance in gaining adequate exposure. Elective incision in the inframammary crease provides excellent exposure and an acceptable scar ( Fig 1.1-16a ).

Fig 1.1-16a–b a Outline of a planned incision in the inframammary crease for harvest of a composite costochondral graft. b Exposure of the rib at the bone/cartilage junction.

Dissection requires incision and reflection of the fascia of the intercostal muscles. The rib is exposed in a subperiosteal plane laterally which facilitates rapid dissection ( Fig 1.1-16b ). For harvest of composite grafts, the medial harvest must be accomplished superficial to the periosteum/perichondrium at the costocartilage junction. This transition requires a precise and delicate approach. The cartilage is then incised with a blade and the deep dissection along the costocartilage junction completed. The rib is then gently retracted laterally and a piezotome or a saw is used to cut the rib at the lateral extent of the required harvest. Rib cutters tend to fracture the rib at the site of the osteotomy and should therefore not be used.

Rigid stabilization of the graft with lag screws should typically be completed after appropriate contouring. It is important to use a bone plate segment as a washer at each screw placement site to prevent splitting of the rib graft. Likewise, the screw sites selected should be staggered to prevent splitting the rib ( Fig 1.1-17 ).

Fig 1.1-17a–c a Costochondral graft. Note the intact perichondrium/periosteum at the junction. b The costochondral graft has been inserted. Segments of a bone plate have been used as washers to help distribute the forces of the lag screw over the weak bone. c Placement and fixation of the graft and hardware can be seen in this postoperative image.
2.4 Bone dust

Small quantities of small particle nonvascularized bone, also called bone dust, can be harvested through bone scraping and bone dust collection from the surface areas of cortical bone. Bone dust can be used for defect filling of minor bone defects, periimplant augmentation, or filling of osteotomy gaps and burr holes.

Bone scraping has been introduced with the advent of piezoelectric surgery. Special bone scrapers are available for piezotomes. They look like small chisels and are used to scrape off bone particles from cortical bone areas, such as the chin region, the mandibular body and angle, the zygomatic alveolar crest, or the cranial vault. The scraped off small cortical bone particles are collected in a bone collector, which is integrated into the suction device ( Fig 1.1-18 ) [Benninger et al, 2012; Alt et al, 2003; Zaffe et al, 2007; Kainulainen et al, 2006; Graziani et al, 2007; Jackson et al, 1988].

Fig 1.1-18a–c a Bone dust collected with a piezotome and bone scraper from the oblique ridge of the mandible. b Bone collector (metal piece) connected to suction device. c Bone collector opened, bone dust removed.

Bone dust collection with a bone collector may also be used in conjunction with almost any bone cutting technology, such as a rose or Lindemann burr.

3 Microvascular bone flaps

3.1 Ilium

The microvascular iliac bone flap is based on the deep circumflex iliac artery (DCIA) and accompanying veins. The DCIA leaves the external iliac artery on its medial aspect normally 1–3 cm cranially to the inguinal ligament. Venous drainage is usually by two accompanying veins, which mostly form a common trunk 1–2 cm before the external iliac vein is reached. The two veins have complex connective branches and sometimes rather resemble a vascular network than two distinct vessels. The DCIA and accompanying veins run superior to the inguinal ligament and reach the inner aspect of the ilium underneath the fascia of the iliac muscle 1–3 cm from the inner cortex of the anterior ileum. An ascending branch of the DCIA supplies the internal oblique muscle allowing simultaneous transfer on one vascular pedicle ( Fig 1.1-19 ). This tissue is most commonly used for replacement of missing mucosa or skin because of the thickness and immobility of the skin portion of the flap that is available. A skin island can also be harvested together with a microvascular iliac bone flap. The vascular supply to the skin is via musculocutaneous perforator vessels ( Fig 1.1-20 ).

Fig 1.1-19a–b a The vascular supply of the flap depends on the deep circumflex iliac artery (DCIA) and vein(s) (DCIV). The vessels originate from the external iliac vessels and run laterally and upward underneath and parallel to the inguinal ligament. They reach the ilium underneath the anterior superior iliac spine and continue in a groove between the transverse abdominis and iliacus muscle. An ascending branch runs upward underneath the internal oblique muscle. b An ascending branch from the DCIA is running superiorly underneath the obliquus abdominis muscle. Three main anatomical variations of the ascending branch have been described, which need to be respected during flap harvest. In 65% of cases, the ascending branch originates from the DCIA within 1 cm medial to the ASIS. In 20 % of cases there is no single dominant ascending branch. The internal oblique is supplied by a series of small branches of the DCIA . In 15% of cases, the ascending branch originates in a more medial and proximal location.
Fig 1.1-20 The skin island of an osteomusculo-cutaneous flap is nourished via perforating vessels, which are located medial to the iliac crest. They should be located centrally within the skin portion.

One significant advantage of the iliac free flap is that the surgeon can harvest bone of whatever height is necessary. This results in the ability to tailor the height of the reconstruction, which facilitates dental implant-based maxillofacial rehabilitation [Urken et al, 1991].

The patient is positioned supine, the donor area should be lifted by underlying sheets or a cushion ( Fig 1.1-21 ). The operative field is prepared widely and draped. The area exposed should extend medially to the linea semilunaris, superiorly to the level of the lower ribs, laterally as far as possible (at least past the iliac tubercle), and inferior about 4 cm below the groin. If a skin paddle is desired, it must be created from directly over the iliac crest. Landmarks for dissection are the reliably palpable femoral vessels, the ASIS, and the iliac crest ( Fig 1.1-22 ). Identification and preservation of the musculocutaneous perforators that supply the skin may be difficult intraoperatively. The perforators can be identified by Doppler ultrasound and marked on the skin before surgery. Many surgeons prefer to use the internal oblique muscle instead of a skin island for intraoral softtissue reconstruction.

Fig 1.1-21 Patient position for iliac bone flap harvest.
Fig 1.1-22 Landmarks for dissection are the femoral artery, which can be reliably palpated, the anterior superior iliac spine (ASIS) and the iliac crest.

The flap can be harvested in two different sequences. After identification of the deep circumflex iliac vessels, the dissection can be performed by identification and dissection of the vascular pedicle, followed by separation of the softtissue flap components before finally the osteotomy is made to mobilize the bony portion (center to periphery). It is also possible to harvest the soft-tissue flap components (skin, internal oblique muscle) first, then follow the vascular pedicle down to its origin at the external iliac vessels, and then perform the osteotomy (periphery to center).

For a center to periphery approach, the vascular pedicle is identified through a skin incision, which follows the course of the inguinal ligament on a line between pubic tubercle and ASIS ( Fig 1.1-23 ).

Fig 1.1-23 Skin incision for harvest of an osteomuscular flap with or without additional internal oblique muscle.

The femoral artery can be palpated and is exposed. Below the inguinal ligament the superficial circumflex artery usually leaves the femoral artery on its lateral aspect and is useful for intraoperative orientation. 2–3 cm above the superficial artery the DCIA will leave the external iliac artery in a lateral and upward direction. Medially, the inferior epigastric artery exits the external iliac artery and is another landmark for dissection. The deep circumflex iliac venous drainage system usually consists of two concomitant veins, which are also exposed. After identification of the vascular pedicle the aponeurosis of the abdominal wall musculature will be divided layer by layer within or above the inguinal ligament. The vascular pedicle is freed until immediately below the ASIS ( Fig 1.1-24 ). In this area the lateral cutaneous femoral nerve needs to be identified to preserve it during further dissection.

Fig 1.1-24 The deep circumflex iliac vessels are dissected after identification of the external iliac vessels and division of the fascias of the abdominal wall.

To harvest an osteomusculo-cutaneous flap, the desired and previously marked skin portion is now incised down to the fascia of the external oblique muscle. The muscles are transsected 3–4 cm away from their bone attachment to preserve a muscle cuff containing the perforators ( Fig 1.1-25 ).

Fig 1.1-25 transection of the abdominal wall muscles 3–4 cm away from their attachment to the iliac bone to preserve the perforators to the skin.

The vascular pedicle itself is located close to the junction between transverse abdominal muscle and iliac muscle. The fascia of the iliacus muscle is incised approximately 2 cm away from the inner ilium surface to protect the vascular pedicle. A strip of iliacus muscle is included into the flap. After division of the fascia and superficial muscle fibers the caudally located portion of the iliacus muscle is freed from the bone with a periosteal elevator ( Fig 1.1-26 ).

Fig 1.1-26 After transection the iliacus muscle is stripped caudally to expose the medial surface of the iliac bone.

Finally, the lateral surface of the anterior ilium is exposed by stripping the relevant part of the gluteus medius muscle in a subperiosteal manner ( Fig 1.1-27 ).

Fig 1.1-27 Before bone flap harvest, muscles attached to the lateral side of the ileum are stripped from the bone surface subperiosteally to expose the lateral aspect of the ilium.

If an osteomuscular iliac bone flap with an additional internal oblique muscle component is desired, a curved incision is created 2–3 cm medial to the iliac crest and superior to the groin crease. The incision is carried through the skin, subcutaneous tissue, and the external oblique muscle fascia. The external oblique fascia is thin. After incision, it is retracted and the internal oblique muscle is widely exposed ( Fig 1.1-28 ).

Fig 1.1-28 The thin external oblique fascia is incised and retracted to expose the internal oblique muscle.

The internal oblique muscle is incised in the desired size and reflected laterally. The ascending branch of the DCIA running on the undersurface of the muscle is identified ( Fig 1.1-29 ). A retrograde dissection is now performed along the ascending branch to the main vascular pedicle until the deep circumflex iliac vessels are reached ( Fig 1.1-30 ).

Fig 1.1-29 The internal oblique muscle is incised as needed and raised laterally. The ascending branch of the DCIA, running on the undersurface of the muscle, is identified.
Fig 1.1-30 After isolation of the desired portion of the internal oblique muscle and identification of the ascending branch retrograde dissection is performed along the ascending branch to the deep circumflex iliac vessels.

The vessel dissection is now completed until the whole pedicle is isolated. Care must be taken to avoid injury to the lateral femoral cutaneous nerve. Alternatively, the ascending branch can arise directly from the external iliac artery. In this case two arteries need to be dissected and two arterials anastomoses performed. After isolation of the vascular pedicle the distal end of the DCIA is ligated ( Fig 1.1-31 ).

Fig 1.1-31 After dissection of the vascular pedicle is completed, the distal end of the DCIA is ligated.

After dissection and before the flap is isolated, the vascular pedicle is ligated and divided close to the external iliac vessels as soon as the recipient site is prepared for flap inset ( Fig 1.1-32 ). If no additional soft-tissue components (eg, skin, internal oblique muscle) are needed, only a small portion of the muscles of the abdominal wall respectively their fasciae (transversalis, external oblique, internal oblique) together with a strip of iliacus muscle are included into the flap to protect the vascular pedicle. In doing so an osteomuscular iliac bone flap is created ( Fig 1.1-33a ). If the flap is harvested with a skin island from the groin it is called an osteo-musculo-cutaneous iliac bone flap ( Fig 1.1-33b ).

Fig 1.1-32 Isolated iliac bone flap with additional internal oblique muscle.
Fig 1.1-33a–b a Iliac bone flap without additional soft-tissue components (internal oblique muscle and/or skin). A thin strip of muscles needs to be included to protect the vascular pedicle. b Iliac bone flap with a skin island.

Depending on amount and shape of the bone needed and according to the preoperative planning, the ASIS can either be preserved or included into the flap. If it is possible to preserve the ASIS, this should be done and a minimum of 2–3 cm bone adjacent to the spine should be maintained to minimize the risk of anterior iliac spine fractures. If it is feasible to maintain the ASIS and the bone is therefore harvested more posteriorly it has the positive side-effect that the vascular pedicle will be longer. If the ASIS needs to be included into the flap, the sartorius and tensor fascia latae muscles need to be detached from the bone. After that the lateral surface of the ilium is exposed subperiosteally and the osteotomy is performed from the lateral side. Care must be taken to preserve the vascular pedicle on the medial side during the bone cutting process.

After complete isolation of the flap it should immediately be transferred to the recipient side to avoid longer periods of nonperfusion. The flap may be irrigated with saline solution but is not routinely rinsed with anticoagulants.

Flap contouring may require osteotomies, which can be done as opening or closing osteotomies. As a rule, opening osteotomies will add to bone length, closing osteotomies will reduce length of the bony portion. Inset of a bone flap is typically carried out after opening osteotomies. The osteotomies are always performed through the lateral cortex of the ilium and in a monocortical fashion in order not to harm the vascular pedicle and the soft-tissue components, which are located close to the medial surface of the ilium, respectively the iliac crest. The medial bone is greenstick fractured with finger pressure to allow adaptation of the bone flap ( Fig 1.1-34 ).

Fig 1.1-34 For flap contouring, monocortical osteotomies are performed on the lateral aspect of the ilium (flap). The medial cortex is then greenstick fractured to avoid damage to the vascular pedicle.

Bone flap stabilization with osteosynthesis plates and screws is also always performed on the lateral side of the ilium (see chapter 2.6) ( Fig 1.1-35 ). Flap contouring may be performed while the flap is still connected to the external iliac vessels and perfused.

Fig 1.1-35 The flap is fixed to a reconstruction plate with monocortical screws, bicortical screw placement may damage the vascular pedicle especially during the drilling process. The vascular pedicle lies on the medial side of the ilium, respectively the neomandible.

Meticulous management of the donor site is crucial to avoid complications. To avoid profuse bleeding from the cancellous portion of the remaining ilium, the donor site is sealed with bone wax, fibrin glue, or other local hemostatic agents. The donor site must be reconstructed to avoid hernia formation. The closure of the abdominal wall must be precisely completed in layers. Hernia formation is reduced if support of the closure is provided with polypropylene mesh or similar. The muscles should be reinserted to the bone using sutures through drill holes in the remaining iliac bone ( Fig 1.1-36 ). The muscles and fascia of the abdominal wall should be closed over a suction drain and the skin approximated.

Fig 1.1-36 For better stability of the abdominal wall during wound closure, the muscles of the abdominal wall may be anchored directly to the bone using multiple drill holes.
3.2 Fibula

The microvascular free fibula flap has earned a reputation as a reliable and straightforward means of achieving successful reconstruction of bone defects in the maxillofacial region [Hidalgo et al, 1995]. The flap has been used extensively in mandible reconstruction. Most commonly the flap is used for reconstruction after ablative defects (tumor surgery) or avulsive defects (gunshot wounds). The flap has also been proven to be suitable for maxillary reconstruction (after infrastructure maxillectomy).

Recognized advantages of the flap include large diameter flap vessels, abundant length of available bone, reliable skin paddle, and distant donor site with little donor site morbidity. The most cited criticism of the fibula flap is that the height of the bone is too small for mandible reconstruction. The height of the fibula, in fact, closely approximates that of an edentulous mandible. However, it must be noted that numerous large case series exist, where successful mandibular rehabilitation has been accomplished.

The fibula is the smaller tubular bone of the lower leg. Most important is its role in forming the lateral component of the upper jump joint. Above that it carries only approximately 6% of the load on the lower leg. It has thick cortical layers and not much cancellous bone. In a cross-section, the fibula shows three edges which define the lateral, medial, and posterior facies (see chapter 2.6). The fibula contains an intraosseous artery, but the blood supply to the fibula flap is via the attached muscles and the periosteum. Except for the fibular head and the lateral malleolus, the whole fibula is covered with muscles. From the medial facies of the fibula the margo interosseus arises, to which the interosseous membrane is attached. The lower leg usually contains three vessel nerve bundles, but variations such as a 2-vessel situation are possible. The anterior and the posterior intermuscular septae are running from the superficial fascia of the lower leg to the fibula. Together with the interosseous membrane and the lamina profunda of the fascia cruris, they form well-defined anatomical compartments, which contain the three vascular bundles ( Fig 1.1-37 ).

Fig 1.1-37 Cross-section from the middle portion of the lower leg, view from below. compartments, fascias and neurovascular bundles.

The flexor hallucis longus muscle plays a key role in fibula flap harvest. The muscle parts close to the vascular pedicle need to be incorporated into the flap to protect the vascular bundle and to guarantee periosteal blood supply to the bone. For additional volume, extended flexor hallucis longus muscle components and additional segments of the adjacent soleus muscle can be included into the flap. For a fibula bone flap with skin component (osteomusculocutaneous flap), a skin island over the lateral aspect of the fibula with perforating septocutaneous vessels can be included. The perforators are typically located within the posterior intermuscular septum but may also run through the adjacent musculature ( Fig 1.1-38 ).

Fig 1.1-38a–c Variations of fibula flap design. a Fibula bone flap with small muscle components of flexor hallucis longus muscle and tibialis posterior muscle. b Osteoseptocutaneous fibula flap (with small components). c Osteomusculocutaneous fibula flap with extended components of flexor hallucis longus and soleus muscles.

The flap is based on the peroneal vessels. Preoperative assessment of the donor site is extremely important. Clinical assessment should be corroborated with imaging studies whenever the status of the vasculature is uncertain. If clinical examination reveals any sign of peripheral vascular disease, a magnetic resonance angiogram, CT angiogram or standard angiography should be performed. Congenital abnormalities may also contraindicate the use of the flap, particularly a peroneal dominant circulation ( Fig 1.1-39 ).

Fig 1.1-39 Variations of the peroneal artery. The use of a fibula free flap is contraindicated in patients with inadequate anterior or posterior tibial vessels to avoid compromise of the blood supply to the foot (approximately 8% of the patients).

For flap harvest, the patient is positioned supine and the entire lower extremity is prepared and draped. The recipient site should first be evaluated and appropriate recipient vessels dissected. The presence of good blood flow within those vessels should be demonstrated before commencing flap elevation. This is especially important in the setting of secondary reconstruction, prior neck surgery, and reconstructions for osteoradionecrosis. In some circumstances, such as tumor resection and neck dissection, the harvest can take place simultaneously.

The flap can most easily be harvested after application of a sterile tourniquet above the knee ( Fig 1.1-40 ). However, some surgeons prefer to harvest the flap without tourniquet to be able to see the bleeding. If the recipient site is not ready for flap inset at the time of flap harvest the flap should stay connected to the peroneal vessels until the recipient side is fully prepared. The flap can then be allowed to perfused before transfer to the recipient site. Some clinicians elect to perform osteotomies and plating of the fibula flap while it remains pedicled to minimize ischemia time (see chapter 2.7). Flap contouring today is often done using CAD/CAM cutting guides (see chapter 5.3.12).

Fig 1.1-40 For flap harvest the patient is placed in a supine position with the knee of the donor leg flexed. If a tourniquet is used, it is placed at the middle of the thigh and inflated (up to 90 minutes) to twice the systolic pressure.

If a skin paddle is needed, it is oriented over the lateral intramuscular septum ( Fig 1.1-41 ). Most perforating vessels to the skin are located at the junction of the middle and lower third of the fibula. These vessels may be identified with the use of Doppler ultrasound.

Fig 1.1-41 The fibula free flap donor site and planned harvest of skin flap are outlined in this image. perforators have been identified by Doppler ultrasound and are marked on the skin.

During fibula flap harvest the proximal and distal 6–7 cm of the fibula needs to be preserved to ensure stability of the lower leg, especially of the superior jump joint.

For flap harvest an incision is performed along the lateral aspect of the fibula in a straight or slightly curved manner. The incision should start at least 2 cm inferior to the fibular head to avoid damage to the common peroneal nerve. If a skin island is going to be included, it should have been previously marked and the perforators should have been identified by Doppler ultrasound. The anterior border of the skin island is included into the incision line ( Fig 1.1-42 ).

Fig 1.1-42 The shape of the incision may be curved or a straight line. At the distal end, the desired skin flap is incorporated into the incision. The incision starts 2 cm inferior to the fibular head to avoid damage to the common peroneal nerve.

The skin is incised including the superficial fascia of the lateral compartment. The dissection is continued until the posterior intermuscular septum is reached. Within the septum the perforators are identified ( Fig 1.1-43 ).

Fig 1.1-43 The skin is incised including the fascia of the lateral compartment. The muscles are exposed and the dissection continued posteriorly to identify the perforators to the skin island.

The peroneal muscles are elevated from the periosteum of the fibula and retracted anteriorly to expose the fibular bone. Care should be taken to preserve the periosteum over the bone, especially in the area of the perforators ( Fig 1.1-44 ). Sharp dissection is then carried to the interosseous membrane leaving a thin layer of the extensor hallucis longus muscle attached to the fibula ( Fig 1.1-45 ).

Fig 1.1-44 The peroneal muscles are separated from the periosteum of the fibula and retracted anteriorly to expose the fibular bone. Take care to preserve the periosteum over the bone, especially in the area of the perforator(s).
Fig 1.1-45 Sharp dissection is then carried to the interosseous membrane leaving a thin layer of the extensor hallucis longus muscle attached to the fibula.

To be able to mobilize the bone and for better access the desired bone segment is now osteotomized. To expose the bone a subperiosteal dissection is performed 360° around the fibula only at the planned osteotomy sites ( Fig 1.1-46 ). During the osteotomies the vascular pedicle needs to be protected, for example with periosteal elevators to avoid damage. The osteotomies are performed with oscillating or reciprocating saws ( Fig 1.1-47 ).

Fig 1.1-46 In preparation for the necessary osteotomies, a subperiosteal dissection is performed 360° around the fibula only at the osteotomy sites.
Fig 1.1-47 The osteotomies are performed with a saw. During the bone-cutting process the peroneal vessels are protected with periosteal elevators.

The interosseous membrane is now cut, and the posterior tibialis muscle divided to expose the vascular pedicle ( Fig 1.1-48 and Fig 1.1-49 ).

Fig 1.1-48 The interosseous membrane is cut leaving a few millimeters of the membrane attached to the fibula.
Fig 1.1-49 Dissection is continued into the posterior compartment. The tibialis posterior muscle is divided to expose the pedicle, and a cuff of muscle tissue is left attached to the bone.

The osteotomized bone segment is now mobile and is retracted laterally to have access to the vascular bundle. The distal branches of the pedicle are now identified and ligated ( Fig 1.1-50 ).

Fig 1.1-50 The osteotomized bone segment is retracted and rotated laterally to expose the peroneal vessels. The distal branches of the pedicle are now identified and ligated.

When harvesting an osteoseptocutaneous flap, the posterolateral skin incision is now made down to the fascia and a subfascial elevation of the skin from the soleus muscle is made. Care must be taken to protect the perforators from the peroneal artery during this step. For perforator protection a thin strip of soleus muscle may be included into the flap. ( Fig 1.1-51 ). The fibula segment is rotated laterally and the flexor hallucis is transected from inferior to superior leaving a thin muscle cuff to protect the vascular pedicle ( Fig 1.1-52 ).

Fig 1.1-51 To harvest an osteoseptocutaneous flap, the posterolateral skin incision is now made down to the fascia and a subfascial elevation of the skin from the soleus muscle is made. Be careful to protect the perforators from the peroneal artery during this step.
Fig 1.1-52 While retracting the bone segment, the flexor hallucis longus muscle is transected from inferior to superior leaving a thin muscle cuff to protect the vascular pedicle.

If the skin flap is not needed, the skin perforators can be sacrificed.

The flap is now mobile and for maximum pedicle length the vascular pedicle is dissected in a proximal direction until the bifurcation of the posterior tibialis and the peroneal vessels is reached ( Fig 1.1-53 ). If bone flap contouring through osteotomies is required some surgeons prefer to do this while the flap is still connected and perfused, while others prefer to perform necessary osteotomies on a side table shortly before the recipient site is ready for flap inset. Ligation of the vascular pedicle is the last step of flap harvest ( Fig 1.1-54 ) (see chapter 2.7).

Fig 1.1-53 The proximal pedicle is dissected up to the bifurcation area of the posterior tibialis and the peroneal vessels.
Fig 1.1-54 After identification of the bifurcation, the peroneal vessels are ligated and the pedicle is transected.

After harvest of an osteomuscular fibula flap the donor site can usually be closed primarily. However, it is vital to avoid tension after donor site closure, especially after skin portions have been included into the flap in order to not create a compartment syndrome. If tension is present, a split thickness or thin full thickness skin graft should be used ( Fig 1.1-55 ).

Fig 1.1-55 Wound closure needs to be performed without tension to avoid compartment syndrome. In case of the slightest tension a split thickness or thin full thickness skin graft should be used. A drain is inserted.

Inset of the flap requires assessment of the necessary pedicle length and contouring of the skin paddle. The vessels should be oriented along the medial aspect of the flap. Osteotomies are created after minimal periosteal reflection and are followed by excision of bone wedges with a saw. Refinement of these osteotomies is often necessary and is completed with a burr. The flap can be adapted free hand, with the use of a template or directly to a bone plate. The latter technique offers significant advantage in that the shape of flap has already been determined and the surgeon must simply match it ( Fig 1.1-56 and Fig 1.1-57 ).

Fig 1.1-56 If osteotomies need to be performed be careful not to injure the vascular pedicle. Typically, closing osteotomies are performed. This means that a wedge of bone is taken out, after that the remaining fibular segments are realigned at an angle defined through the wedge. For the planned osteotomies the periosteum should be freed from the bone resected during the closing ostectomy and retracted carefully during the bone cuts. Stripping of excess periosteum for the closing ostectomy will put vascular supply to the segment at risk.
Fig 1.1-57 The bone is adapted to the overlaying plate as much as possible to avoid large bone-plate gaps. The individual fibula segments should not be less than 2.5 cm in length.

Bone contouring can also be done with cutting guides produced with CAD/CAM technology (see chapter 5.3.12). The bone flap is first stabilized with monocortical screws in the flap and bicortical screws in the neighboring mandible, after that the soft-tissue inset is performed. Microvascular anastomosis is then completed and the flap evaluated for appropriate perfusion.

3.3 Scapula

The scapula is a triangular-shaped bone with a thin center portion, whereas the lateral border of the scapula has a corticocancellous structure. Scapula bone flaps are shorter compared to iliac and especially fibula flaps, although with interindividual variations. The scapula bone flap is less commonly used in maxillofacial bone reconstruction because it requires intraoperative repositioning of the patient. It offers, however, a significant advantage over the other free bone flaps as it can be harvested with several separately mobile skin paddles [Sullivan et al, 1989]. Usually the lateral border of the scapula provides enough bone even for segmental mandible reconstruction. The lateral border has a slightly helical shape ( Fig 1.1-58 ).

Fig 1.1-58a–b Anatomy of the scapula.

The individual size can be assessed through preoperative computed tomographic imaging. Pedicled on the circumflex scapular artery and frequently two accompanying veins, bone flaps with a thickness of approximately 1.5 cm, a width of approximately 3 cm, and a length of 10–14 cm can be harvested. The bone quality is, however, variable and may not always be relied on to support dental implant-based rehabilitation. The flap is often used in reconstruction of large maxillectomy defects and through and through defects involving the mandible. Blood supply to the scapula bone flap is through the circumflex scapular vessels, which mostly originate from the subscapular vessel system ( Fig 1.1-59 ).

Fig 1.1-59 Subscapular arterial system.

As a variation the circumflex scapular vessels can originate from the axillary artery. The arteries are typically accompanied by veins. It is important to know that veins of the scapular drainage system may have valves. The vascular axis containing the circumflex scapular artery can be elongated in dissecting the subscapular vessels up to the axilla. Through this technique a long vascular pedicle of approximately 12–14 cm can be created if necessary. On the subscapular vascular axis, the scapular bone flap can be combined with a scapular or parascapular fasciocutaneous or a musculocutaneous flap from the latissimus dorsi muscle. Various flap combinations are possible. Most frequently a parascapular, scapular, and/or latissimus dorsi soft-tissue flap is combined with a bone flap from the lateral border of the scapula, a serratus anterior flap may also be included. From the tip of the scapula a vascularized bone flap pedicled on the angular branch from the thoracodorsal vessels can be isolated. This angular bone flap can be used alone or in combination with a bone segment from the superior portion of the lateral border. In the latter case this allows for a more independent insert of the two separate bone segments ( Fig 1.1-60 ).

Fig 1.1-60 From the lateral border of the scapula two bone flaps with independent vascular supply can be harvested. The superior part of the lateral border is supplied via the circumflex scapular artery, while the tip region is supplied via the angular branch coming from the thoracodorsal artery.

The scapula has multiple muscle attachments on both sides. The blood supply to the bone is via attached muscles and the periosteum. Therefore, a muscle cuff along the lateral border of the scapula needs to be preserved during bone flap harvest ( Fig 1.1-61 ).

Fig 1.1-61 View from posterior with muscles attached to the scapula. The circumflex scapular artery goes through the triangular space. Finally, it will bifurcate into two cutaneous branches (scapular and parascapular artery).

The scapular flap is harvested with the patient in lateral position. The cutaneous branches of the circumflex scapular artery run horizontally about midway between the scapular spine and tip and vertically parallel to the lateral border of the scapula. These cutaneous branches can be located at the triangular intersection (triangular space) of the teres major, teres minor and the long head of the triceps brachii muscles. Dissection landmarks are the acromion, the lateral border of the scapula, and the tip. The triangular space is located and marked through palpation ( Fig 1.1-62 ).

Fig 1.1-62 A scapular flap is raised with the patient positioned on his or her side. Landmarks for dissection are the scapular tip, the acromion, the lateral border of the scapula and the usually palpable triangular space.

For harvest of a combined scapular (fascio)cutaneous and a scapula bone flap, the scapular flap is raised over a vascular axis that runs parallel to the scapular spine approximately in the middle between scapular tip and scapular spine. If the bone is going to be harvested together with a parascapular flap, it is important to know that the parascapular vessel axis lies parallel to the lateral margin of the scapula, and the vessels to the skin run in a subcutaneous plane. The flap is marked on the skin and the skin incisions and subfascial dissection are completed first.

For harvest of a scapular bone flap the dissection starts laterally and continues in a medial direction toward the triangular space and the vascular axis ( Fig 1.1-63 ). The inferior and/or medial aspect flaps should be elevated toward the triangular space to allow visualization of the branches before completing the superior skin incision ( Fig 1.1-64 ).

Fig 1.1-63 Starting medially, the skin is incised down to the deep fascia of the skin and a subfascial elevation from the infraspinatus muscle is performed.
Fig 1.1-64 As the flap is raised, the pedicle on the undersurface of the cutaneous layer can be identified.

For bone flap harvest, the skin incision is extended vertically and inferiorly to provide a better overview over the operation field and to allow for dissection of the vascular pedicle of the scapular soft-tissue flap into the triangular space until its origin from the circumflex scapular artery is identified. Vessel dissection continues until the bifurcation of the subscapular artery and the circumflex scapular artery has been identified ( Fig 1.1-65 ).

Fig 1.1-65 A vertical skin incision is made at the lateral edge to allow for the retraction of the skin and the dissection of the pedicle. The dissection is continued laterally until the teres minor muscle is encountered and the origin of the pedicle can be found in the triangular space. Meticulous dissection is performed to expose the circumflex scapular artery up to the bifurcation (maximum limit) of the subscapular artery.

The skin incision is completed, and the flap is mobilized from the underlying muscles.

The blood is supplied to the lateral scapula by many small periosteal branches of the circumflex scapular artery. To preserve these branches, a small cuff of teres major and minor muscle is maintained with the scapula. The latissimus dorsi muscle is then identified and retracted allowing excellent visualization of the thoracodorsal, circumflex scapular and angular vessels. The thoracodorsal artery is then ligated (unless the latissimus muscle is also being transferred).

The teres minor muscle is incised first horizontally in a length of approximately 3 cm medially from the lateral border of the scapula ( Fig 1.1-66 ). Then the teres minor and major muscles are incised and divided parallel to the lateral border of the scapula ( Fig 1.1-67 ). A small cuff of the teres minor and major muscles is left attached to the scapular bone to protect the blood supply of the bone flap. The medial parts of teres major and minor muscles are retracted, and an osteotomy is performed as planned with a saw ( Fig 1.1-68 ).

Fig 1.1-66 The teres minor muscle is incised horizontally over a length of approximately 3 cm from the lateral border of the scapula.
Fig 1.1-67 The teres major and teres minor muscles are then transected parallel to the lateral border of the scapula. After that the medial parts of the muscles are retracted and the bone is exposed.
Fig 1.1-68 Osteotomies performed as planned with a saw.

The scapular osteotomies are completed after transecting the infraspinatus muscle maintaining a 2 cm cuff along the lateral edge of the scapula.

The upper osteotomy line remains just below the insertion of the long head of the triceps brachii corresponding to a point approximately 2 cm caudal to the lower edge of the glenoid fossa. The medial osteotomy is performed approximately 2 cm medial to the lateral border of the scapula. For reconstruction of the palate a wider strip of bone can be harvested. The tip of the scapula can be harvested separately if the angular vessels are preserved. Following completion of the osteotomies, the bone is rotated and a 2 cm cuff of the subscapularis muscle is maintained on the deep surface of the scapula completing the flap elevation ( Fig 1.1-69 ). The flap pedicle is then dissected proximally to achieve the desired length before vessel ligation. The bone or combined bone and soft-tissue flap is now completely isolated on its vascular pedicle ( Fig 1.1-70 ). The harvest is then completed, the flap set aside, and the donor site closed.

Fig 1.1-69 The bone is retracted laterally and freed from the subscapularis muscle inserting into the anterior surface of the scapula. A muscle cuff is left attached to the bone.
Fig 1.1-70 The flap is now completely mobilized and the pedicle is transected.

The teres major muscle should be directly sutured to the scapula through drill holes placed for that purpose. The overlying skin is then mobilized and approximated in layers over a closed suction drain. The teres major muscle is responsible for internal rotation, extension and adduction of the arm. The morbidity of the flap harvest is not insignificant. Even when repaired well, significant limitation of mobility may remain.

The patient is then repositioned, and the bone flap inserted and stabilized with monocortical screws before inset of the skin and microvascular anastomosis. It is important to work quickly to avoid prolonged ischemia of the flap.

Pedicled on the thoracodorsal vessels, more flap combinations can be harvested including components of the latissimus dorsi muscle and/or a separate tip flap from the scapula. In addition, a parascapular flap can be included. If no vessel variation is present all the flaps can be raised based on the subscapular vessel system ( Fig 1.1-71 ). Those complex flaps are also called chimeric flaps.

Fig 1.1-71 Chimeric flap with multiple tissue components pedicled on the subscapular vessels. It includes a (fascio) cutaneous scapular and parascapular flap, two independent scapular bone flaps and a latissimus dorsi flap.
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Nov 2, 2020 | Posted by in Oral and Maxillofacial Surgery | Comments Off on 1 Bone grafts, bone flaps, bone replacement materials and techniques
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