RECONSTRUCTIVE Classification of Mandible Defects and Algorithm for Microvascular Reconstruction Benjamin D. Schultz, B.A. Michael Sosin, M.D. Arthur Nam, M.D., M.S. Raja Mohan, M.D. Peter Zhang, B.S. Saami Khalifian, B.A. Neil Vranis, B.S. Paul N. Manson, M.D. Branko Bojovic, M.D. Eduardo D. Rodriguez, M.D., D.D.S. Baltimore, Md.; and New York, N.Y.

Background: Composite mandibular tissue loss results in significant functional impairment and cosmetic deformity. This study classifies patterns of mandibular composite tissue loss and describes a microvascular treatment algorithm. Methods: A retrospective review of microvascular composite mandibular reconstruction from July of 2005 to April of 2013 by the senior surgeon at the R Adams Cowley Shock Trauma Center and at The Johns Hopkins Hospital yielded 24 patients with a mean follow-up of 17.9 months. Causes of composite mandibular defects included tumors, osteoradionecrosis, trauma, infection, and congenital deformity. Patients with composite tissue loss were classified according to missing subunits. Results: A treatment algorithm based on composite mandibular defects and microvascular reconstruction was developed and used to treat 24 patients. A type 1 defect is a unilateral dentoalveolar defect not crossing the midline and not extending into the angle of the mandible. A type 2 defect is a unilateral defect extending beyond the angle. A type 3 defect is a bilateral defect not involving the angles. A type 4 defect is a bilateral defect with extension into at least one angle. Type 2 defects were the predominant group. Patients had microvascular reconstruction using either fibula flaps (n = 19) or iliac crest flaps (n = 5). Complications included infection, partial necrosis, plate fracture, dehiscence, and microvascular thrombosis. Conclusion: This novel classification system and treatment algorithm allows for a consistent and reliable method of addressing composite mandibular defects and focuses on recipient vasculature and donor free flap characteristics.  (Plast. Reconstr. Surg. 135: 743e, 2015.) CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

M

andibular defects following tumor resection or trauma can be disabling both functionally and aesthetically. Multiple approaches exist in reconstructing complex, critically sized mandibular defects to restore form and function. The difficulty of successful reconstruction is selecting From the Division of Plastic, Reconstructive and Maxillofacial Surgery, R Adams Cowley Shock Trauma Center; the Department of Plastic and Reconstructive Surgery, The Johns Hopkins University School of Medicine; the University of Maryland School of Medicine; and the Department of Plastic Surgery, New York University Langone Medical Center, Institute of Reconstructive Plastic Surgery. Received for publication May 20, 2014; accepted October 14, 2014. Presented at the American Society for Reconstructive Microsurgery Annual Meeting, in Kauai, Hawaii, on January 11 through 14, 2014; and poster presentation at the D.C. American College of Surgeons All Surgeons Day, in Washington, D.C., on March 8, 2014. Copyright © 2015 by the American Society of Plastic Surgeons DOI: 10.1097/PRS.0000000000001106

an ideal approach with which to achieve consistent and optimal outcomes. Restoration of mandibular defects with associated composite tissue loss complicates flap selection, which makes management challenging.1 Composite mandibular tissue loss from trauma and oncologic resection results in significant functional and cosmetic deformities.2,3 Intact contralateral muscles can result in malocclusion, which limits range of motion and impairs lateral and protrusive movements on opening or closing.4 Disclosure: None of the authors has a financial interest in any of the products or devices mentioned in this article. Supplemental digital content is available for this article. Direct URL citations appear in the text; simply type the URL address into any Web browser to access this content. Clickable links to the material are provided in the HTML text of this article on the Journal’s Web site (www.PRSJournal.com).

www.PRSJournal.com

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Plastic and Reconstructive Surgery • April 2015 Restoration of mandibular continuity and functionality, and attempting to return patients to their premorbid state, is the ultimate goal of reconstruction. Reestablishing jaw function, including chewing, swallowing, oral competence, and speech, is essential to providing successful execution of microvascular reconstruction.4 To achieve these goals, the reconstructive surgeon must address bony continuity, tongue mobility, and restoration of sensation to denervated areas. The majority of complex defects result from oncologic ablation and resection of the oropharynx and oral cavity.4 However, causes such as trauma, congenital deformities, and osteoradionecrosis contribute to the pool of patients requiring reconstruction. These patients are often left with a complex, large defect that necessitates restoration of form to achieve successful rehabilitation.5,6 The mainstay of composite mandibular reconstruction consists of bony stabilization with autogenous, nonvascularized bone grafts or vascularized bone grafts and soft-tissue coverage.7 Defects of critical size that require a large volume of bone necessitate harvesting bone from distant donor sites. The evolution of microsurgery has improved the complex, functional, and aesthetic outcomes of oromandibular reconstruction with the use of radial forearm, scapula, iliac crest, and fibula free flaps.8 The use of osseous vascularized free flaps has allowed for a consistent method of reconstruction, with success rates of greater than 90 percent.4,8,9 Creating a simple, practical classification and management algorithm with universal acceptance has proven to be difficult. A commonly known system from Boyd et al.10 was designed to account for the various possible combinations of mandibular subunit defects. However, it does not adequately address surgical treatment. Other classification systems have been developed for the classification and treatment of complex mandible defects that focus on different aspects of the recipient site for primary consideration.8,9,11 However, our experience has found these algorithms to be cumbersome and unable to adequately address the complex nature of large mandible defects. Therefore, the purpose of this article is to report the use of a novel classification system that simplifies the patterns of mandibular composite tissue loss, and provides an algorithm for microvascular reconstruction.

PATIENTS AND METHODS A retrospective review of the senior surgeon’s (E.D.R.) experience at the R Adams Cowley Shock Trauma Center and The Johns Hopkins Hospital

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from July of 2005 to April of 2013 of patients who underwent microvascular reconstruction for mandibular defects 5 cm or larger following composite tissue loss was performed. A total of 24 patients were included for review, 15 male and nine female patients, with a mean age of 52.2 years (range, 15 to 64 years). Causes of the defects included osteoradionecrosis (n = 11), benign and malignant tumors (n = 5), trauma (n = 4), infection (n = 2), and congenital deformities (n = 2). The mean follow-up time was 17.9 months (range, 12 days to 84 months). Classification The choice of an osseous flap for mandibular reconstruction depends on pedicle length requirement and the availability of donor tissue. A classification of mandibular defects has been created that focuses on mandibular functional subunits that require reconstruction. Iliac crest or fibular free flaps are ideal choices for reconstruction of the aforementioned defects. Our classification system is based on the ascending order of reconstructive complexity (Fig. 1): a type 1 defect consists of a unilateral dentoalveolar defect that does not cross the midline; a type 2 defect includes a unilateral dentoalveolar defect extending beyond the angle; a type 3 defect involves bilateral defects of the dentoalveolar regions without extending beyond either angle; and a type 4 defect consists of bilateral dentoalveolar defects extending beyond either one or both angles. Each type is further subdivided based on whether or not the ipsilateral vasculature is available (A) or not available (B) for anastomosis, with the latter being a situation that would require use of the contralateral neck vasculature. Subsequently, the proposed free flap in our algorithm is based on the required pedicle length. For type 2 defects, it should be noted whether or not the associated condyles are intact, as this helps determine which free flap should be used for reconstruction. If unilateral condylar involvement exists, the deficit would be labeled a type 2Ac/Bc; however, if the condyles are not involved, the deficit would be classified as a type 2A/B. The algorithm for classifying and managing type 3 deficits is similar to that of type 1 because the deficit is limited to the dentoalveolus; as such, condylar involvement does not need to be addressed. Type 4 deficits require multiple approaches because of the almost complete mandibular involvement.

RESULTS Based on composite tissue microvascular flaps, an algorithm was developed and used to treat

Volume 135, Number 4 • Classification of Mandible Defects

Fig. 1. Flow chart of algorithm for mandibular defect classification and microsurgical repair. A, viable ipsilateral vasculature; B, nonviable ipsilateral vasculature; c, condylar involvement; DCIA, deep circumflex iliac artery (iliac flap); FOSC, fibula osteoseptocutaneous flap; VG, vein graft.

24 patients with composite mandibular defects. Reconstructive details are listed in Table 1. Type 2 defects were predominant (n = 12), followed by type 3 (n = 6), type 1 (n = 5), and type 4 (n = 1) defects in our series. Patients received either a free fibula flap (n = 19) or an iliac crest flap (n = 5). The recipient arterial vessels used were the facial artery (n = 13), superior thyroid artery (n = 7), external carotid artery (n = 2), lingual artery (n = 1), and posterior auricular artery (n = 1). The venous recipient vessels included the facial vein (n = 11), internal jugular vein (n = 11), and external jugular vein (n = 7). Nine of the 24 patients experienced minor complications, which included 12.5 percent partial necrosis of the flap (n = 3), 8.3 percent wound dehiscence (n = 2), 8.3 percent infection not requiring débridement (n = 2), 4.2 percent hematoma (n = 1), and 4.2 percent malocclusion (n = 1). Three of the 24 patients experienced a major complication, which included 8.3 percent hardware removal (n = 2) and 4.2 percent venous

thrombosis of microvascular anastomosis with subsequent complete flap failure (n = 1). The mean number of reoperations per patient was 0.17.

CASE REPORTS Type 1 Defects Case 1

A 59-year-old man presented with osteoradionecrosis of the right mandible with an orocutaneous fistula following radiation treatment for tonsillar cancer (Fig. 2).12 After débridement, the patient was left with a 7-cm defect in the right dentoalveolar region. A 7 × 3-cm iliac crest free flap from the right hip was used for reconstruction. The ipsilateral facial artery and both external and internal jugular veins were used for vascular anastomosis (type 1A). By 5-month follow-up, there was complete resolution of the orocutaneous fistula and the patient exhibited good mandibular function without complication. Donor-site morbidity was minimal, and the patient went on to have successful implantation of prosthodontics.

Case 2

A 60-year-old man underwent left radical neck dissection, left tonsillar resection, and external beam irradiation at an outside hospital for squamous cell carcinoma of the left tonsil. He

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Plastic and Reconstructive Surgery • April 2015 Table 1.  Patient Summary Patient Sex

Age (yr)

MOI

Location of Mandibular Defect

Ips or Contra Vasc

Type of Mandibular Defect

Flap Type

Recipient Vessels

1 2

M M

59 60

ORN SCC

Right Left

Ips Ips

1A 1A

3

M

29

GSW

Left

Ips

1A

Iliac

STA/IJV

4

M

23

Left

Ips

1A

Iliac

STA/IJV

5 6

M M

64 32

Right Right

Contra Ips

1B 2A

Fibula Fa/Fv Fibula Fa/EJV × 2

7 8

M M

85 56

Blunt trauma SCC Odontogenic keratocyst ORN ORN

Left Left

Ips Ips

2A 2A

9

M

55

ORN

Right

Ips

2A

Iliac STA/IJV Fibula Lingual artery/IJV, EJV Fibula Fa/Fv, IJV

10 11

M F

46 15

ORN Goldenhar syndrome

Left Right

Ips Ips

2Ac 2Ac

12

M

21

GSW, OM

Right

Ips

2Ac

Fibula STA/EJV Fibula Postauricular artery/EJV, IJV Iliac STA/IJV

13

F

54

Osteoma

Right

Contra

2B

Fibula

Fa/Fv

14 15

F M

81 56

ORN ORN

Left Right

Contra Contra

2B 2B

Fibula Fibula

Fa/Fv STA/IJV

16 17

M F

48 53

Right Left

Contra Contra

2B 2Bc

Fibula Fibula

STA/EJV Fa/Fv

18

M

50

Bilateral

Ips

3A

Fibula Fa/EJV, IJV

19 20 21 22

F M F F

52 63 52 72

ORN Osteosarcoma Ameloblastoma OM SCC ORN ORN

Right Bilateral Bilateral Bilateral

Ips Ips Contra Contra

3A 3A 3B 3B

Fibula Fibula Fibula Fibula

Fa/Fv ECA/Fv ECA/IJV Fa/Fv

23 24

F F

56 18

Left Bilateral

Contra Contra

3B 4

Fibula Fibula

Fa/Fv Fa/Fv

GSW McCuneAlbright syndrome

Iliac Fa/EJV, IJV Fibula Fa/Fv

Complications Donor-site infection Infection of hardware/ fistula Skin necrosis Plate fracture Malocclusion

Follow-Up (mo) 0.5 65 30 5 34 2 4 10

Wound dehiscence Plate fracture

Skin necrosis, hematoma Abscess/ infection Malocclusion, exposed hardware, nonunion Wound dehiscence

Infection Vessel thrombosis

1 24 12 2.5 4 14 38

2 32 7 84 18 0.5 8 17 16

MOI, mechanism of injury; M, male; F, female; GSW, gunshot wound; ORN, osteoradionecrosis; SCC, squamous cell carcinoma; OM, osteomyelitis; Fa, facial artery; Fv, facial vein; STA, superior thyroid artery; IJV, internal jugular vein; EJV, external jugular vein; ECA, external carotid artery; Ips, ipsilateral; Contra, contralateral; Vasc, vasculature.

presented to our institution 13 years later with an orocutaneous fistula in the left parasymphyseal region (Fig. 3).13 He was edentulous and a smoker. The patient underwent free fibula osteoseptocutaneous flap surgery with a split-thickness skin graft. He underwent two revision operations, which consisted of debulking of subcutaneous tissue and cervicofacial flap advancement for cosmetic enhancement, 6 months after the original operation.

Type 2 Defects Case 3

A 22-year-old man sustained a gunshot wound to the right face. After multiple washouts and débridements, a right retromolar mandibular fossa defect was present. Six days after the initial injury, he underwent reconstruction with a sternocleidomastoid rotational flap to cover the retromolar defect, but the mandibular defect of the right dentoalveolus and ramus persisted. He presented to us

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11 months later with impaired mandibular function and a right type 2A defect (Fig. 4). He then underwent a free iliac osteocutaneous flap (7 × 2-cm bone, 10 × 2-cm skin paddle) reconstruction to the right mandibular defect. Anastomosis was to the ipsilateral internal jugular vein and to the superior thyroid artery. The flap experienced venous congestion requiring partial débridement of soft tissue; however, the bone and the majority of the remaining soft tissue were viable. At 5-week follow-up, the patient was able to achieve normal mandibular function and ultimately received successful prosthetic dental implants.

Case 4

A 56-year-old man with a history of squamous cell carcinoma of the right tonsil was treated with chemotherapy and radiation therapy. Three years later, the patient developed right osteoradionecrosis with a concomitant pathologic fracture. He underwent partial mandibulectomy with application of a reconstruction bar,

Volume 135, Number 4 • Classification of Mandible Defects

Fig. 2. Type 1 defect reconstructed with iliac crest free flap (case 1). (Above, left) Preoperative three-dimensional computed tomographic scan depicting a right mandibular defect. (Above, center) Clinical photograph of an orocutaneous fistula. (Right) An iliac crest free flap (with internal oblique muscle) was anastomosed to the ipsilateral internal jugular vessels (arrow) to reconstruct the 7-cm composite mandibular defect (ellipse). (Below, left) Postoperative computed tomographic scan and (below, center) resolution of orocutaneous fistula 1 year after reconstruction with an iliac crest free flap. (Reprinted with permission from Kelishadi SS, StHilaire H, Rodriguez ED. Is simultaneous surgical management of advanced craniofacial osteoradionecrosis cost-effective? Plast Reconstr Surg. 2009;123:1010–1017.) and a sternocleidomastoid muscle flap to close intraoral defects. Unfortunately, he developed an orocutaneous fistula with progression of osteoradionecrosis. At this point, the patient was referred to our clinic, and his evaluation revealed a 9.5-cm right dentoalveolar and ramus defect without condylar involvement. Based on our classification, this is defined as a type 2B defect. A free fibula osteoseptocutaneous flap consisting of 9.5 cm of bone and a 14 × 12-cm skin flap was used for reconstruction (Fig. 5). The peroneal vascular pedicles were anastomosed to the contralateral superior thyroid artery and internal jugular vein. Eight months later, the reconstruction bar was removed, and excess skin, subcutaneous tissue, muscle, and bone were débrided to enhanced cosmesis. Thereafter, the patient underwent further revision operations to repair an Angle class 2 malocclusion. Follow-up at 38 months demonstrated full form and function without further complication.

Type 3 Defects Case 5

A 56-year-old woman sustained injuries to the craniofacial region from a self-inflicted shotgun wound. At an outside hospital, multiple débridements and washouts were performed, midface fractures were rigidly fixated, and a reconstruction plate was used to span a 12-cm bilateral dentoalveolar mandibular bony defect (type 3B). Seven weeks after the initial injury, she

was referred to our clinic for definitive mandibular reconstruction (Fig. 6). She underwent reconstruction with a free fibula osteocutaneous flap to the left mandible and cheek. The contralateral facial vessels were used for recipient vascular anastomosis. Ten months after her free flap reconstruction, the mandibular hardware was removed secondary to pain. However, she demonstrated excellent mandibular form and function 19 months postoperatively.

Type 4 Defect Case 6

An 18-year-old female patient presented with McCuneAlbright syndrome with sarcomatous transformation of fibrous dysplasia of the mandible. After hemimandible resection at an outside institution in 1999, she remained disease-free for 2 years. However, she subsequently developed a recurrence in the remaining portion of the mandible. This required complete mandibular resection with titanium plate reconstruction, which remained in place for 3 years. [See Figure, Supplemental Digital Content 1, which is a preoperative three-dimensional computed tomographic scan depicting a type 4 mandibular defect in the patient in case 6, http://links.lww.com/PRS/B259. See Figure, Supplemental Digital Content 2, which is a preoperative clinical photograph. (Reprinted with permission from Rodriguez ED, Bluebond-Langner R, Brazio P, Collins M. Near-total mandible

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Plastic and Reconstructive Surgery • April 2015

Fig. 3. Reconstruction of a type 1 defect using a free fibula flap (case 2). (Above, left) Preoperative computed tomographic scan of the left mandibular body showing osteoradionecrosis. (Above, center) Preoperative clinical photograph. (Above, right) Resection of the necrotic segment of bone resulted in a 5-cm segmental defect on the left mandibular body. Ipsilateral vessels were not available because of radiation-induced fibrosis. A free fibula flap with single-stage dental implant placement. Anastomoses were performed to the contralateral facial vessels. (Below, left) A postoperative computed tomographic scan is shown. (Below, center) Six-month follow-up clinical photograph with (below, right) dental implants in place. (Reprinted with permission from Fisher M, Dorafshar A, Bojovic B, Manson PN, Rodriguez ED. The evolution of critical concepts in aesthetic craniofacial microsurgical reconstruction. Plast Reconstr Surg. 2012;130:389–398.) reconstruction with a single fibula flap containing fibrous dysplasia in McCune Albright syndrome. J Craniofac Surg. 2007;18:1479– 148214), http://links.lww.com/PRS/B260.] The patient sought further reconstructive surgery and underwent a free iliac crest bone graft to the symphyseal region, which left the patient dissatisfied with cosmesis and function, at which point she was referred to our clinic for evaluation. Her defect measured 21 cm bilaterally, extending into the condyles bilaterally. Microvascular reconstruction was performed using a free fibula flap with five osteotomies designed to integrate iliac bone graft to give greater height to the neomandible. (See Figure, Supplemental Digital Content 3, which shows the fibula flap osteotomized and rigidly fixated to create the symphysis and angles of the mandible, http://links.lww.com/PRS/B261.) Her 16-month follow-up demonstrated enhanced mandibular form with improved function.

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[See Figure, Supplemental Digital Content 4, which shows a postoperative three-dimensional computed tomographic scan 1 year after reconstruction with a clinical photograph. (Reprinted with permission from Rodriguez ED, Bluebond-Langner R, Brazio P, Collins M. Near-total mandible reconstruction with a single fibula flap containing fibrous dysplasia in McCune Albright syndrome. J Craniofac Surg. 2007;18:1479–148214), http://links.lww. com/PRS/B262.] Her recovery continued without complication.

DISCUSSION Surgeons have been searching for the ideal solution to complex mandibular defects. Complete restoration of the mandible requires

Volume 135, Number 4 • Classification of Mandible Defects

Fig. 4. Reconstruction of a type 2 defect with an iliac crest free flap (case 3). (Above, left) Intraoperative photograph of the right mandibular defect (body and angle) and presence of the ipsilateral recipient vessels (arrow). (Above, right) Preoperative computed tomographic scan of the patient revealing the defect of the right mandibular body and angle. (Below, left) Inset of the iliac crest free flap. (Below, right) Computed tomographic scan of the patient 1 year after reconstruction.

consideration of many factors, such as sufficient height of the mandible, adequate muscle attachment for form and function, and preservation of neurovascular anatomy. Restoring or improving swallowing, chewing, speech articulation, and oral competence is critical for successful rehabilitation of patients.4–6 The development of a systematic method of assessing, classifying, and summarizing the severity and extent of mandibular injury coupled with surgical management is challenging because of the complex reconstructive nature of mandible defects. Several classification schemes have been designed to address reconstructive scenarios in which a complex mandibular deficit is present.10,11,15,16 Although these systems have been useful for the classification of mandibular defects, many have not been coupled with treatment modalities. Those that do provide algorithmbased treatment modalities are criticized for

being cumbersome and overly complicated to routinely be implemented clinically. For example, Urken et al.8 have designed a detailed and encompassing algorithm for the reconstruction of large composite mandibular defects. Nearly all forms of recipient defects, including bone, softtissue, and neurologic deficits, are considered for selecting a flap. Their scheme for classifying and treating complex mandibular defects is intricate and carefully designed. However, the use of numerous abbreviations for a large number of possible defects fails to create a practical and easily implementable algorithm. Another commonly used algorithm from Takushima et al.11 suggests that the soft-tissue defect is the critical factor for determining the appropriate flap for reconstruction. Although this is an important consideration, our single-surgeon experience found this to be a secondary factor for flap selection. Furthermore, the algorithms described by both Urken et al. and

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Plastic and Reconstructive Surgery • April 2015

Fig. 5. Reconstruction of a type 2 defect using a fibula free flap (case 4). (Above, left) Intraoperative photograph of the type 2 defect involving the right body and angle of the mandible. (Above, right) Procurement of an osteomyocutaneous fibula free flap with creation of the mandibular angle with osteotomy and rigid fixation. (Below, left) Fibula flap inset with donor vessels anastomosed to the contralateral superior thyroid artery and internal jugular vein. (Below, right) Three-dimensional computed tomographic scan of the patient 1 year postoperatively.

Takushima et al. use scapular flaps, a flap choice that adds additional difficulty because of the need to change patient positioning and ultimately was able to be avoided in our experience. The present study demonstrates the successful application of a novel, simplified algorithm that focuses on recipient vascular integrity for the classification and microsurgical management of critically sized, complex mandibular deficits. The proposed algorithm for mandibular defect reconstruction is based on a minimum critical size of 5 cm of osseous deficit. Kademani et al.17 describe the use of free tissue transfer as the treatment modality of choice for large segmental defects of 5 cm or greater, especially those that include the overlying mucosa. Not only does free tissue transfer address significant mandibular defects, it is also less prone to fail in an irradiated surgical site.17 Before the introduction of microvascular free flaps, nonvascularized bone grafts

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were and are still commonly used. Experts recommend using bone grafts for defects that measure 5 cm or smaller, and only if the surrounding soft tissues have adequate vascularity.18–20 Pedicled bone grafts have also been used, but they have fallen out of favor in light of the development of microvascular surgery because pedicled options are extremely limited. Furthermore, the donor sites that are used for pedicled bone grafts may not be available and are subject to significant complications.21 Microvascular surgery has revolutionized repair of the mandible, especially when a significant bony defect is present.21 Currently, the use of autogenous bone grafting is the criterion standard of osseous mandibular reconstruction, as it is the most reliable and predicable modality for complex deficits.4 The most advantageous aspect of mandibular reconstruction with free flaps is the reliability of combining soft tissue and bone in

Volume 135, Number 4 • Classification of Mandible Defects

Fig. 6. Reconstruction of a type 3 defect using an osteomyocutaneous fibula free flap (case 5). (Above, left) Preoperative computed tomographic scan depicting a left type 3 mandibular defect. (Above, center) Intraoperative photograph demonstrating the mandibular defect. (Right) The fibula flap is osteotomized and rigidly fixated to create the natural shape of the mandible. (Below, left) Postoperative computed tomographic scan 1 year after reconstruction with a fibula free flap. (Below, center) Clinical photograph correlating with the 1-year computed tomographic scan.

one operation using one donor site.21 Microvascular surgery allows for the transfer of vascularized bone flaps, which have a reported success rate of 99 percent compared with nonvascularized bone grafts over a 3-year follow-up.6 Even in patients with radiation exposure, success rates exceed 90 percent.9 In fact, loss of implant-mounted dental prostheses in irradiated versus nonirradiated free bone flaps is without substantial difference.21–26 Free tissue transfer before irradiation is associated with a reduced risk of osteoradionecrosis and adjunctive hyperbaric oxygen therapy.19,27 Studies have shown that reconstructions with microvascular free flaps have better outcomes than those with

local myocutaneous flaps. Furthermore, patients receiving free fibula versus iliac crest grafts have shown comparable health-related quality-of-life outcomes.28–30 The flaps that are most commonly used for osseous reconstruction include the fibula, iliac crest, radial forearm, and scapula.4,21 The iliac crest free flap has been widely used since its inception in the 1980s by Taylor et al.,31 and was later refined by Urken et al.,29 who proposed the use of the internal oblique–iliac crest osteomyocutaneous flap. Based on our work, the wide bone stock of the iliac crest bone, which is unmatched in terms of available bone supply, makes it an ideal

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Plastic and Reconstructive Surgery • April 2015 flap for mandibular defects, especially those of the dentoalveolar region.21 Successful use of dental implants in preirradiated vascularized iliac crest bone grafts of greater than 30 months makes this a robust flap in the setting of oncologic resection and osteoradionecrosis.32 Another major advantage is that the ipsilateral iliac crest has a natural contour that resembles that of the hemimandible.4 The height of the iliac crest is similar to that of the native dentate mandible, allowing for the necessary lower lip support, which improves oral competence.7,33 However, one of the most significant disadvantages of the iliac crest free flap is that it has a short vascular pedicle and an absence of segmental perforating vessels, aspects that make incorporating osteotomies difficult.21 Although rare, donor-site morbidity may cause significant gait disturbances and difficulty ambulating postoperatively. When bicortical bone is removed, the donor site is subject to deformity and, although rare, has the potential to develop abdominal herniation.34 The fibula free flap is a popular choice for mandibular reconstruction because of its multifaceted application. The peroneal artery and vein are used for the flap and are advantageous because of their diameter and length. In our patients, the free fibula flap was used when there was significant damage or irradiation to the ipsilateral vasculature, or when a long segment of bone was needed. Like the free iliac crest flap, the fibula flap can be harvested in the supine position, which allows for a two-team approach and decreases operative time.7 The long pedicle allows for anastomosis to be completed to the contralateral vasculature of the neck, precluding the use of vein grafts or arteriovenous loops. Unlike the iliac crest flap, the fibula receives its blood supply from segmental perforators, which allows for the creation of multiple osteotomies. The fibula can also provide 30 cm of bone length, making it versatile in its application for mandibular reconstruction.21 Moreover, the vascularized free fibula flap is recommended for those with large anterior or bony defects requiring multiple osteotomies because, compared with the iliac crest bone graft, it has a lower rate of resorption and lower failure rate.5 In contrast, a major disadvantage of the free fibula flap is the short bone height, making it less suitable for dentate patients who require dental implants. However, surgical techniques have been designed to overcome this problem.35,36 As such, it remains the first choice for edentulous mandibles and large mandibular resections.21

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The radial forearm flap was first applied for mandibular reconstruction in 1983 by Soutar et al.37 The free flap is designed around its vascular pedicle consisting of the radial artery, vein, and the subcutaneous veins. Like the free fibula flap, the radial forearm flap has a long pedicle, and approximately 10 to 12 cm of bone may be taken. Furthermore, the skin paddle is thin, large, and pliable, qualities that make it ideal for lining the intraoral defect. However, the bone harvested is often thin and lacking in segmental perforators, limiting multiple osteotomies. Furthermore, a lack of height makes it problematic for application of dental implants, and donor-site fractures remain the greatest and most criticized aspect of its use.21 Finally, the scapular flap is a versatile composite flap that allows for restoration of large soft-tissue defects and replacement of bone. It has a single vascular pedicle that can supply large amounts of bone with soft tissue. Its recommended use is for through-and-through defects of the mucosa, bone, and skin.21 However, it must be harvested in the lateral decubitus or prone position, which makes a two-team approach more difficult.7 Also, use of the scapular flap leads to decreased range of motion of the shoulder, especially with arm abduction.7 None of our patients received this free flap. Even with the use of free flaps, reconstruction plates are essential to mandibular defect repair. Ideal plates are those of sufficient size and strength that allow for the stabilization of reconstruction while taking into account the discretionary use of locking screws. These are particularly useful because they minimize compression of the underlying bone by the plate, thereby protecting the vascular supply of the graft.38 However, permanent use of reconstructive plates for bony mandibular stabilization has its disadvantages. Kim and Donoff39 have shown that if the mandible has been irradiated or if the defect crosses the midline, there is a substantial increase in the incidence of complications requiring revision or removal of the plate. However, some surgeons advocate the use of reconstruction plates as a primary means of stabilization before reconstruction 1 year later.40 Our classification system focuses on criticalsize deficits, which we defined as greater than 5 cm, based on their anatomical subunits. Initially, the selection of an appropriate free flap for reconstruction begins with the viability of the recipient vasculature. The subsequent division of deficit types addresses the viability of the desired recipient vasculature and associated

Volume 135, Number 4 • Classification of Mandible Defects wound bed. This approach allows for the simultaneous classification of the deficit, based on the surrounding structural integrity, and aids the surgeon in selecting proper surgical treatment. For example, case 5 (Fig. 5) would be considered a type 2B defect because recipient vessels ipsilateral to the deficit are considered compromised as a result of osteoradionecrosis. The decision to use a free fibula flap was based on its long pedicle and its ability to reach the contralateral vessels. After assessing the viability of the vasculature for anastomosis, determining whether to use an iliac crest free flap or a fibula free flap is a matter of operator preference. Factors such as skin deficit, length of deficit, or the possible need for dentures postoperatively help guide the surgeon’s choice in free flap. It should be noted that certain scenarios necessitate the use of particular free flaps. For example, if a type 2 defect has condylar involvement (type 2Ac/Bc), free fibula flaps are recommended because they provide sufficient length for condylar reconstruction. After the anatomical location of bilaterality of the mandibular defect, our classification system emphasizes the importance of the viability of the recipient vasculature for free flap anastomosis. The mandibular defects included in this study were the result of a variety of causes, each with its own set of possible complications. Minimizing the potential for postoperative complications and subsequent need for reoperation following complex reconstruction is the goal of all surgeons. Flap loss following microvascular reconstruction is associated with three main risk factors: prior operations on the neck, atherosclerosis, and previous radiation treatment.41 Ultimately, readmission rates and complications are to be expected as a result of the risk factors, and some of our patients did require reoperation for postoperative complications. However, in light of these complications, we believe that autogenous, vascularized bone is the most ideal method of reconstructing complex, critical-size mandibular deficits. Even with its numerous advantages, microvascular free flap reconstruction is both time consuming and associated with differing degrees of complication and donor-site morbidities. However, its use in the repair of complex mandibular deficits is superior to alternative forms of repair. Using our classification system and management algorithm for complex mandibular reconstruction aids the surgeon in consistently and reliably treating patients with such defects.

CONCLUSIONS This novel classification system and treatment algorithm is a consistent and reliable method of addressing composite mandibular defects and focuses on recipient vasculature and donor free flap characteristics. The treatment algorithm patterns are useful for classifying and treating defects based on subunit reconstruction of any cause. Iliac crest and fibula free flaps are effective for restoring mandibular function by providing a rich bone stock and long vascular pedicle, respectively. Eduardo D. Rodriguez, M.D., D.D.S. Department of Plastic Surgery New York University Langone Medical Center Institute of Reconstructive Plastic Surgery 305 East 33rd Street New York, N.Y. 10016 [email protected]

PATIENT CONSENT

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