Central Segmental Mandibular Defects

Microvascular bone transfer has resulted in durable anterior arch replacement in the vast majority of cases, far exceeding the results of prior methods of reconstruction. Isolated anterior arch defects can be reconstructed using any of the available favored -g donor sites; however, the associated soft tissue defects may require more discernment |

in choice of the most appropriate flap. Common associated soft tissue defects include ยป

those involving the floor of mouth, lower lip, chin and neck, and tongue. The scapula, iliac crest, and fibula each possess unique attached soft tissue components. The soft tissue components of the iliac crest include a closely attached and relatively thick skin paddle and a thin sheetlike muscular component. The fibula possesses a closely attached thin skin paddle that may be made sensate. Although the scapular system has the least substantial bone of the three flaps, it possesses the most substan- |

tial and adaptable soft tissue components including the transverse scapular and

Figure 2 Stereolithographic model used to adapt a reconstruction plate and bone graft accurately into a segmental mandibular defect.
Figure 4 Osteotomized fibular bone with associated skin paddle draping over the neoalveolus and anterior floor of mouth.

parascapular flaps (sometimes thick), latissimus dorsi muscle and overlying skin, and serratus anterior muscle (and underlying ribs).

Most anterior segmental mandibular defects will have an associated defect of the anterior floor of mouth (Fig. 3). Therefore, at least a portion of the soft tissue component of the free flap must be used to resurface the anterior floor of mouth and close the through-and-through defect in this area. It is fortunate that most resections involve this type of defect and the fibular flap performs well with its thin and pliable skin component draped over the neoalveolus and anterior floor of mouth (Fig. 4). The skin component can also be draped over partial defects of the anterior mobile tongue, if needed. The iliac crest also performs well in this situation. The muscular component of this flap is draped over the neoalveolus and anterior floor of mouth and left to resurface with epithelium. The scapular flap is less desirable because its skin component is relatively thick (Fig. 5). Nevertheless, it can be used if the other flaps are unavailable.

Anterior segmental defects associated with even total loss of the lower lip are best approached by considering the lip defect as a totally separate entity from the mandibular and anterior floor of mouth defect. The lip is best reconstructed independently using advancement or transposition flaps from the opposite lip or cheek because no soft tissue components of an osseous free flap will adequately duplicate the appearance of a natural lip (Fig. 6). As an alternative, a radial forearm free flap -g could be used in addition to the osseous flap to reconstruct the lower lip.

Sometimes the anterior arch defect is associated with a substantial loss of skin over the chin and neck. The fibular flap often proves inadequate to reconstruct the intra- and extraoral soft tissue deficits. However, the iliac crest flap is suitable with its muscular component for the intraoral defect and its skin component for the chin and neck defect (Fig. 7). The fibular flap could be used and the extraoral defect res- |

urfaced with a regional flap (lower island trapezius or pectoralis flap). Although the scapular flap is also suitable, the drawbacks regarding the intraoral reconstruction persist.

Figure 5 Anterior segmental defect reconstructed with a scapular flap. Note the thick skin flap over the anterior floor of mouth displacing tongue superolaterally. 4-point star = parascapular skin flap; 5-point star = remaining tongue.

Figure 6 Secondary reconstruction of the lower lip in a patient reconstructed with a fibular flap. The skin component was used to resurface the anterior floor of mouth (a). The lower lip defect was initially closed with a portion of the skin from the free flap, but healing resulted in the deformity shown. Secondary repair of the lip with a Karapandzic advancement was performed (b-d). Use of the skin from the free flap was clearly inadequate and the patient would have been better served by reconstruction of the lip independently during the initial surgery.

Figure 6 Secondary reconstruction of the lower lip in a patient reconstructed with a fibular flap. The skin component was used to resurface the anterior floor of mouth (a). The lower lip defect was initially closed with a portion of the skin from the free flap, but healing resulted in the deformity shown. Secondary repair of the lip with a Karapandzic advancement was performed (b-d). Use of the skin from the free flap was clearly inadequate and the patient would have been better served by reconstruction of the lip independently during the initial surgery.

Figure 7 Patient with a squamous cell cancer eroding the central and lateral mandibular segments and skin (a). The patient underwent reconstruction with an iliac crest composite flap (b).

Patients with substantial defects of the tongue combined with chin and neck defects often require multiple regional or free flaps. The scapular system of flaps can be used as an alternative. The parascapular and transverse scapular flaps can be used to reconstruct the tongue (if bulk is needed) and the chin/neck defect. Reconstruction of the floor of the mouth often is obviated by the use of the large skin flap for the tongue. If there is an expansive defect in the neck, the musculocu-taneous latissimus component of the scapular system is used.

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