Chapter 45: Mandibular Reconstruction

In general, patients who are likely to undergo postoperative radiotherapy should have autologous reconstruction, preferably using vascularized bone flaps. The principles of malignant tumor resection are that adequate margins are used to achieve complete resection irrespective of the chosen reconstruction method. Margins should not be compromised or tailored to a specific reconstruction type. The cost effectiveness of a reconstructive method is complex to assess and vascularized tissue transfer is expensive and time consuming and is unlikely to be more cost effective in the short term than other techniques. Donor site morbidity is a major consideration in any vascularized or nonvascularized transfer although taking the fibula as an example, most patients would be expected to return to normal or near-normal function after harvest of either vascularized or nonvascularized bone, so it may not make a difference to morbidity which is taken. Perhaps the inclusion of a skin paddle with subsequent need for skin grafting would be a greater concern thereby causing increased, not decreased, morbidity following vascularized bone harvest.1,2

2. Cordeiro PG, Disa JJ, Hidalgo DA, Hu QY. Reconstruction of the mandible with osseous free flaps: a 10-year experience with 150 consecutive patients. Plast Reconstr Surg 1999;104(5):1314–1320 Allowing the mandible to collapse without reconstruction may be acceptable for some ascending ramus or lateral defects, but will lead to deviation of the chin with malocclusion in dentate patients. The outcomes for speech and swallowing are generally good when using this technique. Temporomandibular joint (TMJ) pain is not usually a problem following resection of the joint. Collapse of the mandible is a relatively straightforward procedure so it maintains a role in current practice.1–6

3. Kellman RM, Gullane PJ. Use of the AO mandibular reconstruction plate for bridging of mandibular defects. Otolaryngol Clin North Am 1987;20(3):519–533 4. Schusterman MA, Reece GP, Kroll SS, Weldon ME. Use of the AO plate for immediate mandibular reconstruction in cancer patients. Plast Reconstr Surg 1991;88(4):588–593

The pectoralis major is a workhorse flap for head and neck reconstruction, even with the increased popularity of free tissue transfer. It has many advantages such as the relative ease and speed with which it can be raised, the vascular supply is very reliable (thoracoacromial artery and vein), the reach is adequate for upper neck, and the mandibular region and the donor site are normally closed directly. It allows either muscle only or muscle and skin to be harvested and can be used to reconstruct mandibular, intraoral, or skin defects. The bulge created over the clavicle may be minimized by dissecting the pedicle and reducing muscle bulk at the pivot point. Alternatively, the clavicle can be sectioned but this is not necessary and is rarely performed.1–5

5. Kim MR, Donoff RB. Critical analysis of mandibular reconstruction using AO reconstruction plates. J Oral Maxillofac Surg 1992;50(11):1152–1157

6. Papazian MR, Castillo MH, Campbell JH, Dalrymple D. Analysis of reconstruction for anterior mandibular defects using AO plates. J Oral Maxillofac Surg 1991;49(10):1055–1059, discussion 1059–1060 MANDIBULAR RECONSTRUCTION PLATES 3. Which one of the following is true of mandibular reconstruction plates as a single modality for mandibular reconstruction? The advantages of using mandibular reconstruction plates alone are shorter operating times and avoidance of donor site morbidity. However, extrusion rates are high, especially when used in the anterior mandible. General consensus is that these techniques should be reserved for lateral defects in patients unable to tolerate longer procedures, those with no dentition and display mandibular atrophy, or those with short expected lifespans. Where they are used, they are typically 1.5- to 2.4-mm thick and can use either locking or nonlocking screws into the mandible. Traditional or nonlocking screws simply hold the plate against the bone to create a load-sharing reconstruction. The addition of locking screws that have threaded screw heads that lock into the plate help create a more rigid load-bearing reconstruction. Mandibular reconstruction plates will all fail if the patient survives long enough. Most fail within 18 months, and the mean time is close to 6 months.1–6

The fibula flap is a workhorse flap for mandibular reconstruction and can provide good volumes of soft tissue and bone. Because of the segmental vascular supply, it is safe to perform osteotomies when contouring to match the resected mandible, but it is advisable to maintain lengths of 3 cm and ensure the periosteum is intact in order to avoid vascular compromise. A separate soft tissue flap, such as a radial forearm, is not required in this case as the skin paddle for a fibula can provide the required skin paddle size. Although the skin island was originally thought to be unreliable, this is no longer considered to be the case, with survival rates close to 100%. The fibula is suitable for using osseointegrated dental implants, even though it does lack vertical height compared with the native mandible. It does not need to be double barreled in most instances, but some surgeons prefer to do so when reconstructing anterior midline defects. Pedicle length is a real advantage of this flap and varies from 6 to 10 cm and sometimes even more, meaning that there is usually comfortable reach to the facial artery and tributaries of the internal jugular vein for anastomosis. The skin paddle is based on perforators at the junction of the mid to distal thirds of the leg and this helps to extend pedicle length when distal bone is harvested. The skin paddle is based on perforators from the peroneal vessels, which pass in the posterior crural septum arising from the posterior aspect of the fibula. Preoperatively, they may be identified using handheld Doppler and intraoperatively, they can usually be seen running through the septum from the bone and pedicle to the skin. Weight bearing can be commenced early in the postoperative period (between 2 and 5 days, according to surgeon and patient preference) following fibula flap harvest and most patients can walk normally following this surgery. There are risks of causing damage to other leg nerves and vessels in the anterior, lateral, and posterior compartments. For example, the tibial nerve and vessels as well as the deep peroneal nerve are encountered intraoperatively and may receive traction injuries. Also, the sural and superficial peroneal nerves may be inadvertently damaged during flap harvest leading to altered sensation distally (see Fig. 45.1, Essentials of Plastic Surgery, third edition).1–6

Free vascularized iliac crest bone flaps have a role in mandibular reconstruction and some surgeons prefer to use them instead of the fibula flap. However, this flap carries some additional donor site complications compared with the fibula flap, including risk of postoperative hernia and lower abdominal/hip pain. This can be reduced to some extent by careful reinforced closure of the abdomen during donor site closure. Blood supply is from the deep circumflex iliac artery (DCIA) which arises from the external iliac (not the internal) close to the deep inferior epigastric artery, which is used in a deep inferior epigastric perforator (DIEP) flap. A disadvantage of this flap is its short pedicle (up to 7 cm is typically quoted). This can be improved by moving the site of bone harvest more posteriorly. The skin paddle tends to be bulky and perforating vessels are not consistently present, but muscle can be harvested with the flap to provide intraoral cover. This muscle is the internal oblique (not the external oblique) and mucosalizes rapidly when placed intraorally. The DCIA bone flap provides an excellent foundation for the use of dental implants (see Fig. 45.2, Essentials of Plastic Surgery, third edition).1–4

Deep circumflex iliac artery (DCIA) flaps provide superior bone height when compared with fibula flaps. This may be helpful for placing dental implants, although some surgeons feel that positioning a fibula flap more superiorly at the expense of the inferior mandibular contour or double barreling it anteriorly will address this problem. Although a fibula flap can give more bone length (up to 25 cm in adult males), a DCIA gives adequate length for a hemimandible. Both flaps can provide intraoral soft tissue cover. The fibula flap achieves this with a pliable skin paddle, while the DCIA does so with muscle cover from the internal oblique. Harvest time is probably similar and depends on surgeon’s experience and patient’s body habitus. Both flaps have similar vessel diameter, typically 2–3 mm, so there would not normally be a significant difference in anastomotic difficulty between the two flaps.1–3

The dominant blood supply to the osseocutaneous scapula flap is the circumflex scapular artery arising from the subscapular vessels. The skin islands are termed scapular and parascapular and receive blood supply through the transverse or descending branches of the circumflex scapular artery, respectively. Bone is usually harvested from the lateral border of the scapula commencing 2 cm below the glenohumeral joint toward the scapular tip. In addition to the circumflex scapular artery, the scapula also receives blood supply through the thoracodorsal artery, which normally provides the angular branch to the scapula tip. When raised on the thoracodorsal axis, the flap may include the latissimus dorsi muscle and the overlying skin. It is possible to raise a chimeric flap using both thoracodorsal and circumflex scapular vessels. For this reason, the scapular osseocutaneous flap offers a large amount of soft tissue cover in addition to length of bone, up to 14 cm in adult males. Two main disadvantages of this flap are that patients typically require turning intraoperatively, which may limit a two-team simultaneous approach, and that the bone harvested is thin compared with DCIA or fibula. This means that dental rehabilitation is more challenging and the bone is less easy to sculpt especially as it lacks a segmental blood supply and so cannot withstand osteotomies.1–4

The circumflex scapular pedicle supplies the scapula flaps and passes through the triangular space. This space is formed from the following structures: superiorly, teres minor; inferiorly, teres major; and laterally, long head of triceps (Fig. 45.1).1,2

Computer-aided design is becoming popular as a tool to help plan and execute reconstruction of complex bony defects such as the mandible and maxilla. Three-dimensional computer images of the mandible and fibula are generated and a virtual mandibular defect is created. Cutting jigs are manufactured preoperatively to assist in bony resection and fibula harvest. A major advantage in using models and computer-designed jigs for fibular reconstruction is that the ischemia time can be minimized. This is because the bone flap can be fully prepared while still attached to the leg, with osteotomies performed and the reconstruction plate fitted. Once the flap is disconnected, it needs to be quickly screwed into place and the anastomoses can be started within a few minutes of transfer. The other advantage is the accuracy with which the reconstruction is performed. Even with practice and skill, hand sculpting bony flaps cannot match the accuracy and efficiency of using preplanned jigs. As a result, time in the OR is reduced and quality of reconstruction is improved. The other outcomes such as contour aesthetics, correct occlusion, bony union, and temporomandibular joint (TMJ) dynamic function should all be improved by accurate planning. However, this approach is costly and requires additional time for preplanning. Whether this translates into improved functional outcomes is unknown although intuitively it should do so (see Fig. 45.4, Essentials of Plastic Surgery, third edition).1–4