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Mandibular reconstruction with the iliac crest, composite, microsurgical free flap
MANDIBULAR RECONSTRUCTION WITH THE ILIAC CREST, COMPOSITE, MICROSURGICAL FREE FLAP SALEH M. SHENAQ, MD, MICHAEL J.A. KLEBUC, MD, JAY SHENAQ, MD, AND TUNC SAFAK, MD
The iliac crest microsurgical free flap continues to be engaged in a gradual evolution. After Taylor's description of the deep circumflex iliac artery (DCIA) as the region's predominant vascular supply,21a series of modifications have been contrived that provide more complex reconstruction and thorough oromandibular rehabilitation. This article reviews the deep circumflex iliac vascular anatomy with new insights on cutaneous perfusion. A technical description of flap elevation is provided. Additionally, the benefits of the split inner cortex modification, internal oblique muscle incorporation, and elevation of the cutaneous component as an axial pattern flap are examined. Copyright 9 1996by W.B. Saunders Company
The iliac crest microsurgical free flap is a cornerstone of mandible reconstruction. The iliac crest donor site provides a large (14-16 cm), advantageously curved segment of corticocancellous bone in conjunction with a consistent vascular pedicle, the deep circumflex iliac artery (DCIA), which averages 8 to 10 cm in length and 1.5 to 2.5 mm in diameter. 1 Additionally, the extensive vascular territory of the deep circumflex iliac system sanctions incorporation of a (10 • 15 cm) soft tissue cutaneous island and a segment of internal oblique muscle, which can be denervated and skin grafted to provide a source of oral lining. Because the donor site can yield skin, soft tissue, muscle, and bone, simultaneously (tripartite flap) or in multiple combinations, it provides the reconstructive surgeon unprecedented flexibility. 2 The iliac crest microsurgical free flap is a vehicle via which complex, through and through, oromandibular defects can be closed primarily by using a single donor site and anastomosis. 3 Since its inception in the late 1970s the iliac crest microsurgical free flap has undergone a series of refinements. Recent modifications in flap design have sought to address the following: (1) donor site morbidity, (2) excessive bone thickness, and (3) bulk and immobility of the soft tissue cutaneous island. Conjointly, improved fixation techniques, temporomandibular joint reconstruction, osteointegrated dental implants, inferior alveolar nerve grafting, and sensate flaps have all contributed to improved oromandibular rehabilitation. 4-12 Traditionally, the iliac crest microsurgical free flap is harvested with a bicortical segment of iliac bone. In our hands, removal of bicortical bone has resulted in (1)
From Baylor College of Medicine, Houston, TX. Address reprint requests to Saleh M. Shenaq, MD, Department of Surgery, Baylor College of Medicine, 6560 Fannin, Suite 800, Houston, TX 77030. Copyright 9 1996 by W.B. Saunders Company 1071-0949/96/0304-000955.00/0
flattening of iliac contour, (2) increased frequencies of hernia and abdominal wall weakness, (3) excessive intraoperative bleeding, (4) increased postoperative hematoma and seroma formation, (5) gait disturbance, and (6) increased rates of lateral thigh hypesthesia. In response to the excessive donor site morbidity, the principal author introduced the split inner cortex modification, which has established itself over the past 6 years as our preferred method of mandible reconstruction. 5,6The vascular pattern of the deep circumflex iliac vessels sanctions the removal of a single cortex. The segmental periosteal arteries enter the bicortical bone through its medial cortex supplying serial vascular territories. Thus, the ilium can be split and the inner cortex harvested and subjected to contouring osteotomies without fear of vascular compromise. Preservation of the outer cortex maintains pelvic contour, partitions the viscera within the pelvic inlet, and provides good suture purchase, facilitating a sturdy closure (Fig 1). There have been no hernias in our series since the introduction of this technique. 13 The split inner cortex microsurgical free flap has proved technically easier, less time consuming to harvest, and has been associated with decreased intraoperative blood loss and postoperative hematoma-seroma formation. Correspondingly, the breadth of the single cortex more precisely emulates that of the native mandible reducing the frequent hypertrophied, corpulent appearance of the operated side. The bone stock has proved adequate for contouring osteotomies, A / O internal fixation, and dental restoration with osseointegrated implants. The soft tissue cutaneous component has persisted as the Achilles' heel of iliac crest mandible reconstruction. Traditionally, the cutaneous island is harvested with a large soft tissue mass to dampen shearing forces, which could compromise the row of musculocutaneous perforators supplying the peri-iliac skin. Unfortunately, this soft tissue anchor greatly reduces ones ability to rotate the cutaneous island independently of the bone, complicating flap insetting. The cumbersome subcutaneous tissues undergo mini-
Operative Techniques in Plastic and Reconstructive Surgery, Vol 3, No 4 (November), 1996: pp 289-294
289
Fig 1. Split inner cortex modification of the lilac crest microsurgical free flap. Preservation of the outer cortex maintains pelvic contour and greatly reduces the incidence of incisional hernia,
mal involution and frequently require secondary defatting24 The bulky nature of the cutaneous component limits its use for oral lining because it can inhibit tongue mobility and may obliterate the buccal and lingual sulci. A Series of dye injection studies and clinical investigations performed at our institution have identified the presence of a dominant musculocutaneous perforator in approximately 30% of cases, which is capable of independently supplying the peri-iliac skin island. 1~ Harvesting the skin as an axial pattern flap greatly increases its independence from the bone, improving maneuverability. A small collar of abdominal muscle is incised around the pedicle obviating the need for the customary 2.5-cm protective muscle cuff. Exclusion of the abdominal muscle component reduces the flap's volume, decreases the need for secondary debulking, and reduces donor site morbidity 16 (Fig 2). Conservative, primary defatting has also been well tolerated.
path that parallels the inguinal ligament. En route, the vessels are crossed by the lateral femoral cutaneous and ilioinguinal nerves. Fortuitous division of these nerves produces a troublesome, anesthesia-paresthesia of the groin and lateral thigh. The DCIA, in approximately 80% of cases, liberates a discernible ascending branch to the internal oblique muscle. In 65% of cases a single ascending branch ( d i a m e t e r - 1.0 mm) takes off from the parent vessel within I cm of the ASIS and penetrates the transversus abdominis muscle and then arborizes on the undersurface of the internal oblique. Fifteen percent of the time, the branch arises within 2 to 4 cm of the ASIS. In the residual 20%, the ascending branch is replaced by a series of three to four small vessels. 23 Based on the ascending branch, a paddle of the flat, pliant, internal oblique muscle can be denervated, skin grafted, and incorporated as a source of oral lining. Additionally, the mobility provided by the axial nature of the flap permits the internal oblique muscle to be folded over the associated bony segment to reconstruct the lingual and buccal sulci. 24 After liberating several branches to the external oblique and transversus abdominis muscles, the DCIA continues on a radial course along the inner aspect of the ilium in a plane contiguous with the investing fascia of the iliacus muscle. As the vessel runs along the concavity of the ilium it provides a series of periosteal arteries (Fig 3). The periosteal branches enter the ilium through the inner Dominant perforator frnrn RC:.I•
Iliac a., v. ch) oblique m.
ANATOMY
The DCIA and its tributaries are the foundation of the iliac crest microsurgical free flap. The DCIA provides the principal osseous blood supply and is capable of supporting a 14- to 16-cm segment of iliac, cortiocancellous bone27 Perforators from the DCIA can sustain a region of skin (10 • 15 cm) directly over the iliac crest. However, the principal blood supply to the skin is provided by the superficial inferior epigastric and the superficial-circumflex iliac arteries. 14,18,19Their vascular territory is an elliptical region extending from the pubic tubercle to the posterior superior iliac spine. Dominance can be exerted by either the superficial-circumflex iliac artery or the superficial inferior epigastric artery with the perforators of the DCIA and lumbar arteries augmenting flow directly over the iliac crest. 2~ The DCIA is a branch of the external iliac artery (EIA) (Fig 3). It originates from the parent vessel (EIA) immediately proximal to the inguinal ligament. The DCIA and its venae comitantes course toward the anterior superior iliac spine (ASIS) in a plane deep to the transversalis fascia on a
290
Fig 2. lilac crest harvested as an osteomyocutaneous free flap (tripartite), The cutaneous component has been elevated as an axial pattern flap based on a dominant "piercing vessel" from the DClA. The lilac bone has been split to preserve pelvic contour and prevent a corpulent appearing hemimandible. SHENAQ ET AL
ASIS and terminate at a distance of 8 to 10 cm from that landmark. A dominant cutaneous branch was consistently identified. 25 The concept of a dominant cutaneous perforator is supported by a series of anatomic and clinical investigations performed at our institution, is In approximately 30% of individuals studied, a dominant musculocutaneous branch originated from the DCIA 5 to 6 cm posterior to the ASIS. After diverging from the parent vessel, they pierce the abdominal muscles approximately 2 cm above the iliac crest and follow a direct, perpendicular course to the skin. The dominant perforating vessel on average is 1.5 mm in diameter and 6.0 cm in length and perfuses a 10 • 15-cm cutaneous territory above the iliac crest (Fig 5). These vessels are distinguished from traditional musculocutaneous perforators in that they provide a minimal number of radial muscular branches and their sole purpose is perfusion of the periliac skin island. To this end, they have been labeled "piercing branches" to delineate this difference, a~
Subc
Musculc DCIA
SURGICAL
Fig 3, Vascular anatomy of the deep circumflex iliac vascular network,
cortex, supplying serial vascular territories. Concomitantly, the DCIA provides a series of musculocutaneous perforators to perfuse a 10 • 15-cm cutaneous territory above the iliac crest (Fig 4). Taylor's experimental work describes an average of 6.5 musculocutaneous perforators piercing the abdominal musculature in a plane 1.0-2.5 cm above the iliac crest. The row of perforators initiate at the Perforating branch of
The surgery is initiated with the patient in the supine position with a small role situated under the distal lumbar region. After routine skin preparation and draping, the femoral pulse is identified and a vertical incision (approximately 5 cm) is fashioned over the femoral vessels and extended cephalad to a point approximately 2 cm above the inguinal ligament. The incision is then curved laterally, pursuing an oblique course to the ASIS. The completed incision resembles a reverse L with the long limb parallel to the inguinal ligament. After completion of the skin incision, attention is redirected to the infrainguinal region. Blunt dissection is used Dominant perforating branch
a,
iac a.
anch
Fig 4. The DCIA liberating a series of small musculocutaneous perforators (0,3-0,5 mm) as it courses along the iliac crest, These vessels pierce the abdominal muscles approximately I cm above the lilac crest to supply the overlying skin. This is the predominant pattern of blood supply to the skin, ILIAC CREST MICROSURGICAL FREE FLAP
TECHNIQUE
ra.
iliac a. ranch
Fig 5, The dominant direct cutaneous artery (piercing branch) of the DCIA. An axial pattern skin island can be elevated on this vessel and its venae comitantes, The dominant piercing branch is present in approximately 30% of cases and is on average 1,5 mm in diameter and 6 cm in length,
291
to expose the femoral sheath. The sheath is not violated but provides a landmark for the more cephalad dissection. The suprainguinal dissection is initiated approximately 2 to 3 cm above the inguinal ligament in line with the lateral margin of the femoral sheath. A clamp is employed to spread the fascia of the anterior abdominal wall, exposing the origin of the DCIA and veins at the external iliac vessels in the preperitoneal space. The internal ring and spermatic cord should lie inferomedial. The fascia of the anterior abdominal wall and more lateral musculature is incised parallel to the inguinal ligament to a point several centimeters medial to the ASIS. The fascia is reflected, exposing the deep circumflex iliac vessels running above the iliacus muscle en route to the iliac crest. The vessels are freed from their connective tissue attachments using tenotomy scissors. If the reconstruction requires a section of internal oblique muscle, great care is exercised at this stage of the dissection because the origin of the DCIA can be variable. Typically, the ascending branch to the internal oblique takes off from the DCIA approximately 1 cm proximal to the ASIS. However, intermittently, one will find the vessels originating as far proximal as the external iliac.23 The region of internal oblique to be harvested is now outlined, but its elevation is deferred until dissection of the cutaneous island is completed. If a cutaneous paddle is necessary, its dissection is begun at this point. The technique employed is determined by the requirements of the reconstruction.
Technique 1 When bulky, soft tissue fill is required or neotongue reconstruction is contemplated, the traditional technique is
Fig 7. Flap explored and split.
used. 26A skin ellipse, up to 10 • 15 cm, is marked out over the midiliac crest, and the dissection is begun along the superior border of the flap and carried down to the external oblique muscle. The skin, subcutaneous tissue, and fascia are elevated en bloc with the intention of safeguarding the musculocutaneous perforators to the skin. The dissection is continued inferiorly in this plane and is terminated several centimeters above the iliac crest. The row of cutaneous perforators traverse the abdominal wall approximately 1 cm above the iliac crest. To ensure their preservation, the abdominal wall musculature is incised approximately 2.5 cm above the iliac crest to house the vessels in a "protective cuff" of muscle. 27 Attention is now focused on the inferior portion of the skin island. The dissection is resumed in the same plane and continued cephalad up to the superior pole of the iliac crest. A common approach is then followed to elevate the osseous component.
Technique 2 If a thin, axial-pattern skin flap is desired, an alternate technique is used. Again, a skin-soft tissue island, up to 10 • 15 cm, is elevated over the midiliac region from superior-to-inferior. The incision is initiated along the superior border and extended down to the external oblique
Fig 6. Mandibular defect.
292
Fig 8. Flap dissected and raised. SHENAQ ET AL
ing the initial o s t e o t o m y d o w n to the anterior inferior iliac spine, a n d incorporating the ASIS into the b o n e graft p r o d u c e s a b o n y s e g m e n t that can be inverted to simulate the m a n d i b u l a r angle and r a m u s (Fig 6 and 7). The vascular pedicle exits b e h i n d the n e w l y fashioned angle and is usually sufficient for microvascular anastomosis (artery, 1.5-2.5 m m ; vein, 2.5-3.0 mm). 1 The 8- to 10-cm pedicle length w a r r a n t s unfettered access to the external carotid system. The b o n e s e g m e n t is freed b u t the nutrient vessels are not ligated until the time of actual transfer (Fig 8 a n d 9). A careful, layered closure of the d o n o r site is then p u r s u e d . The residual internal oblique muscle is fixed to the p e r i o s t e u m of the iliac crest w i t h heavy, interrupted, proline sutures a n d the external oblique is anchored to the outer cortex of the iliac crest. Drill holes for suture fixation h a v e not been required. Several closed suction drains are placed t h r o u g h the adjacent skin, a n d Scarpa's fascia a n d skin are closed in the usual layered fashion. O n the third p o s t o p e r a t i v e d a y a p r o g r a m of progressive a m b u l a t i o n is initiated.
REFERENCES
Fig 9. (A) Flap inset,(B) Fixated withmandibular reconstruction plate, fascia. The dissection continues inferiorly in this plane, a n d great care is taken to skeletonize a n d preserve the r o w of skin perforators. If a d o m i n a n t p e r f o r a t o r (piercing branch) is identified, the residue of the skin flap is elevated, a n d the accessory perforators are serially ligated while clinically m o n i t o r i n g flap perfusion. The process is continued until the skin island exists as axial pattern, cutaneous flap p e r f u s e d solely b y the d o m i n a n t piercing b r a n c h of the DCIA. The dissection then proceeds t h r o u g h the a b d o m i nal muscles p r e s e r v i n g a 1-cm m u s c u l a r collar a r o u n d the piercing branch. After isolating the piercing branch, the insertion of the a b d o m i n a l muscles is freed f r o m the iliac crest to expose the u n d e r l y i n g fossa. The skin island can n o w be conservatively defatted w i t h o u t complication. H a r v e s t i n g of the osseous c o m p o n e n t is not influenced b y the m e t h o d of cutaneous elevation. The p e r i o s t i u m is incised along the superior pole of the iliac crest a n d reflected f r o m the midline. If required, the p a d d l e of internal oblique is h a r v e s t e d at this time. Now, the iliacus muscle is reflected to expose the m e d i a l cortex, a n d the osteotomies begin. Initially, a sagittal s a w is e m p l o y e d to bisect the ilium to establish cortical independence. Subsequent transverse a n d posterior osteotomies d e t e r m i n e the height a n d length of the n e o m a n d i b l e respectively. ExtendILIAC CREST MICROSURGICAL FREE FLAP
1. Swartz WM, Banis JC: Flaps from the groin, in: Head and Neck Surgery. Baltimore, ME),Williams and Wilkins, 1992, pp 62-72 2. Shenaq SM, Klebuc MJ: The iliac crest microsurgical free flap in mandible reconstruction. Clin Plast Surg 21:37-43,1994 3. Urken ML, Vickery C, Weinberg H, et al: The internal oblique-iliac crest osseomyocutaneous free flap in oromandibular reconstruction. Arch Otolaryngol Head Neck Surg 115:339-349, 1989 4. Shenaq SM, Klebuc MJ: TMJ reconstruction during vascularized bone graft transfer to the mandible. Microsurgery 15:299-304, 1994 5. Matloub HS, Larson DL, Kuhn JC, et al: Lateral arm free flap in oral cavity reconstruction: A functional evaluation. Head Neck 11:205-211, 1989 6. Urken ML, Weinberg H, Vickery C, et al: The neurofasciocutaneous radial forearm flap in head and neck reconstruction: A preliminary report. Laryngoscopy 100:161-173,1990 7. Obeid G, Guttenberg SA, Connole PW: Costochondral grafting in condylar replacement and mandibular reconstruction. J Oral Maxillofac Surg 48:177-182,1988 8. Schusterman MA, Reece GP, Kroll SS, et al: Use of the AO plate for immediate mandibular reconstruction in cancer patients. Plast Reconstr Surg 88:588-593, 1991 9. Kloch DW, Prein J: Mandibular reconstruction using AO plates. Am J Surg 154:384-388,1987 10. Riediger D: Restoration of masticatory function by microsurgically revascularized iliac crest bone grafts using enosseous implants. Plast Reconstr Surg 81:861-876, 1988 11. Wenig BL, Keller AJ: Rigid internal fixation and vascularized bone grafting in mandibular reconstruction. Clin Plast Surg 16:125-131, 1989 12. Sanger JR, Head MD, Matloub HS: Enhancement of rehabilitation by use of implantable adjuncts with vascularized bone grafts for mandible reconstruction. Am J Surg 156:243-247, 1988 13. Shenaq SA: Split-inner cortex iliac crest microsurgical free flap: A new refinement for mandibular reconstruction. Presented at the American Association of Plastic Surgeons Meeting, San Antonio, TX, April 14-17, 1991 14. Kuriloff DB, Sullivan MJ: Mandibular reconstruction using vascularized bone grafts. Otolaryngol Clin North Am 24:1391-1418,1991 15. Safak T, Klebuc MJ, Shenaq SM: New concepts in fascioucutaneous flaps. Plastic Surgical Forum, ASPRS Meeting, San Diego, CA, 1994 16. Safak T, Klebuc MJ, Shenaq SM, et al: New concepts in fasciocutaneous flaps. Plastic Surgery Educational Foundation Scholarship Contest, 1st paper for Junior Clinical Research Award, 1994 17. Manchester W: Some technical improvements in the reconstruction of the mandible and temporomandibular joint. Plast Reconstr Surg 50:249-256, 1972
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18. Harii K, Ohmori K, Toril S, et al: Free groin skin flaps. Br J Plast Surg 19.
20. 21.
22.
28:225-237,1975 Taylor GI: Reconstruction of the mandible with free composite iliac bone graft. Ann Plast Surg 9:361-376, 1982 Safak T, Klebuc MJ, Kecik A: Closure of upper extremity soft tissue defects using the new "supra-crest" fasciocutaneous free flap. Plast Reconstr Surg (in press) Taylor IG, Palmer JH: The vascular territories (angiosoms) of the body: Experimental study and clinical applications. Br J Plast Surg 40:113-117,1987 Hartrampf CR, Noel TR, Orazon L: Ruben's fat pad for breast reconstruction: A peri-iliac soft tissue free flap. Plast Reconstr Surg 93:402-404, 1994
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23. Ramasastry SS, Granick MS, Futrell JW: Clinical anatomy of the internal oblique muscle. J Reconstr Microsurgery 2:117-122,1986 24. Urken ML: Composite free flaps in oromandibular reconstruction. Arch Otolaryngol Head Neck Surg 117:724-732, 1991 25. Taylor GI, Corlett RJ: Microvascular free transfer of a compound deep circumflex groin and iliac crest flap to the mandible, in Strauch B, Vasconez LO, Hall-Findlay EJ (eds): Grabb's Encyclopedia of Flaps (Vol 1). Boston, MA, Little Brown, 1990, pp 589-599 26. Salibian AH, Rappaport L Allison G: Functional oromandibular reconstruction with the microvascular composite groin flap. Plast Reconstr Surg 76:819-828, 1985 27. Daniel RK: Mandibular reconstruction with free tissue transfers. Ann Plast Surg 1:348-367,1978
SHENAQ ET AL
The iliac crest microsurgical free flap continues to be engaged in a gradual evolution. After Taylor's description of the deep circumflex iliac artery (DCIA) as the region's predominant vascular supply,21a series of modifications have been contrived that provide more complex reconstruction and thorough oromandibular rehabilitation. This article reviews the deep circumflex iliac vascular anatomy with new insights on cutaneous perfusion. A technical description of flap elevation is provided. Additionally, the benefits of the split inner cortex modification, internal oblique muscle incorporation, and elevation of the cutaneous component as an axial pattern flap are examined. Copyright 9 1996by W.B. Saunders Company
The iliac crest microsurgical free flap is a cornerstone of mandible reconstruction. The iliac crest donor site provides a large (14-16 cm), advantageously curved segment of corticocancellous bone in conjunction with a consistent vascular pedicle, the deep circumflex iliac artery (DCIA), which averages 8 to 10 cm in length and 1.5 to 2.5 mm in diameter. 1 Additionally, the extensive vascular territory of the deep circumflex iliac system sanctions incorporation of a (10 • 15 cm) soft tissue cutaneous island and a segment of internal oblique muscle, which can be denervated and skin grafted to provide a source of oral lining. Because the donor site can yield skin, soft tissue, muscle, and bone, simultaneously (tripartite flap) or in multiple combinations, it provides the reconstructive surgeon unprecedented flexibility. 2 The iliac crest microsurgical free flap is a vehicle via which complex, through and through, oromandibular defects can be closed primarily by using a single donor site and anastomosis. 3 Since its inception in the late 1970s the iliac crest microsurgical free flap has undergone a series of refinements. Recent modifications in flap design have sought to address the following: (1) donor site morbidity, (2) excessive bone thickness, and (3) bulk and immobility of the soft tissue cutaneous island. Conjointly, improved fixation techniques, temporomandibular joint reconstruction, osteointegrated dental implants, inferior alveolar nerve grafting, and sensate flaps have all contributed to improved oromandibular rehabilitation. 4-12 Traditionally, the iliac crest microsurgical free flap is harvested with a bicortical segment of iliac bone. In our hands, removal of bicortical bone has resulted in (1)
From Baylor College of Medicine, Houston, TX. Address reprint requests to Saleh M. Shenaq, MD, Department of Surgery, Baylor College of Medicine, 6560 Fannin, Suite 800, Houston, TX 77030. Copyright 9 1996 by W.B. Saunders Company 1071-0949/96/0304-000955.00/0
flattening of iliac contour, (2) increased frequencies of hernia and abdominal wall weakness, (3) excessive intraoperative bleeding, (4) increased postoperative hematoma and seroma formation, (5) gait disturbance, and (6) increased rates of lateral thigh hypesthesia. In response to the excessive donor site morbidity, the principal author introduced the split inner cortex modification, which has established itself over the past 6 years as our preferred method of mandible reconstruction. 5,6The vascular pattern of the deep circumflex iliac vessels sanctions the removal of a single cortex. The segmental periosteal arteries enter the bicortical bone through its medial cortex supplying serial vascular territories. Thus, the ilium can be split and the inner cortex harvested and subjected to contouring osteotomies without fear of vascular compromise. Preservation of the outer cortex maintains pelvic contour, partitions the viscera within the pelvic inlet, and provides good suture purchase, facilitating a sturdy closure (Fig 1). There have been no hernias in our series since the introduction of this technique. 13 The split inner cortex microsurgical free flap has proved technically easier, less time consuming to harvest, and has been associated with decreased intraoperative blood loss and postoperative hematoma-seroma formation. Correspondingly, the breadth of the single cortex more precisely emulates that of the native mandible reducing the frequent hypertrophied, corpulent appearance of the operated side. The bone stock has proved adequate for contouring osteotomies, A / O internal fixation, and dental restoration with osseointegrated implants. The soft tissue cutaneous component has persisted as the Achilles' heel of iliac crest mandible reconstruction. Traditionally, the cutaneous island is harvested with a large soft tissue mass to dampen shearing forces, which could compromise the row of musculocutaneous perforators supplying the peri-iliac skin. Unfortunately, this soft tissue anchor greatly reduces ones ability to rotate the cutaneous island independently of the bone, complicating flap insetting. The cumbersome subcutaneous tissues undergo mini-
Operative Techniques in Plastic and Reconstructive Surgery, Vol 3, No 4 (November), 1996: pp 289-294
289
Fig 1. Split inner cortex modification of the lilac crest microsurgical free flap. Preservation of the outer cortex maintains pelvic contour and greatly reduces the incidence of incisional hernia,
mal involution and frequently require secondary defatting24 The bulky nature of the cutaneous component limits its use for oral lining because it can inhibit tongue mobility and may obliterate the buccal and lingual sulci. A Series of dye injection studies and clinical investigations performed at our institution have identified the presence of a dominant musculocutaneous perforator in approximately 30% of cases, which is capable of independently supplying the peri-iliac skin island. 1~ Harvesting the skin as an axial pattern flap greatly increases its independence from the bone, improving maneuverability. A small collar of abdominal muscle is incised around the pedicle obviating the need for the customary 2.5-cm protective muscle cuff. Exclusion of the abdominal muscle component reduces the flap's volume, decreases the need for secondary debulking, and reduces donor site morbidity 16 (Fig 2). Conservative, primary defatting has also been well tolerated.
path that parallels the inguinal ligament. En route, the vessels are crossed by the lateral femoral cutaneous and ilioinguinal nerves. Fortuitous division of these nerves produces a troublesome, anesthesia-paresthesia of the groin and lateral thigh. The DCIA, in approximately 80% of cases, liberates a discernible ascending branch to the internal oblique muscle. In 65% of cases a single ascending branch ( d i a m e t e r - 1.0 mm) takes off from the parent vessel within I cm of the ASIS and penetrates the transversus abdominis muscle and then arborizes on the undersurface of the internal oblique. Fifteen percent of the time, the branch arises within 2 to 4 cm of the ASIS. In the residual 20%, the ascending branch is replaced by a series of three to four small vessels. 23 Based on the ascending branch, a paddle of the flat, pliant, internal oblique muscle can be denervated, skin grafted, and incorporated as a source of oral lining. Additionally, the mobility provided by the axial nature of the flap permits the internal oblique muscle to be folded over the associated bony segment to reconstruct the lingual and buccal sulci. 24 After liberating several branches to the external oblique and transversus abdominis muscles, the DCIA continues on a radial course along the inner aspect of the ilium in a plane contiguous with the investing fascia of the iliacus muscle. As the vessel runs along the concavity of the ilium it provides a series of periosteal arteries (Fig 3). The periosteal branches enter the ilium through the inner Dominant perforator frnrn RC:.I•
Iliac a., v. ch) oblique m.
ANATOMY
The DCIA and its tributaries are the foundation of the iliac crest microsurgical free flap. The DCIA provides the principal osseous blood supply and is capable of supporting a 14- to 16-cm segment of iliac, cortiocancellous bone27 Perforators from the DCIA can sustain a region of skin (10 • 15 cm) directly over the iliac crest. However, the principal blood supply to the skin is provided by the superficial inferior epigastric and the superficial-circumflex iliac arteries. 14,18,19Their vascular territory is an elliptical region extending from the pubic tubercle to the posterior superior iliac spine. Dominance can be exerted by either the superficial-circumflex iliac artery or the superficial inferior epigastric artery with the perforators of the DCIA and lumbar arteries augmenting flow directly over the iliac crest. 2~ The DCIA is a branch of the external iliac artery (EIA) (Fig 3). It originates from the parent vessel (EIA) immediately proximal to the inguinal ligament. The DCIA and its venae comitantes course toward the anterior superior iliac spine (ASIS) in a plane deep to the transversalis fascia on a
290
Fig 2. lilac crest harvested as an osteomyocutaneous free flap (tripartite), The cutaneous component has been elevated as an axial pattern flap based on a dominant "piercing vessel" from the DClA. The lilac bone has been split to preserve pelvic contour and prevent a corpulent appearing hemimandible. SHENAQ ET AL
ASIS and terminate at a distance of 8 to 10 cm from that landmark. A dominant cutaneous branch was consistently identified. 25 The concept of a dominant cutaneous perforator is supported by a series of anatomic and clinical investigations performed at our institution, is In approximately 30% of individuals studied, a dominant musculocutaneous branch originated from the DCIA 5 to 6 cm posterior to the ASIS. After diverging from the parent vessel, they pierce the abdominal muscles approximately 2 cm above the iliac crest and follow a direct, perpendicular course to the skin. The dominant perforating vessel on average is 1.5 mm in diameter and 6.0 cm in length and perfuses a 10 • 15-cm cutaneous territory above the iliac crest (Fig 5). These vessels are distinguished from traditional musculocutaneous perforators in that they provide a minimal number of radial muscular branches and their sole purpose is perfusion of the periliac skin island. To this end, they have been labeled "piercing branches" to delineate this difference, a~
Subc
Musculc DCIA
SURGICAL
Fig 3, Vascular anatomy of the deep circumflex iliac vascular network,
cortex, supplying serial vascular territories. Concomitantly, the DCIA provides a series of musculocutaneous perforators to perfuse a 10 • 15-cm cutaneous territory above the iliac crest (Fig 4). Taylor's experimental work describes an average of 6.5 musculocutaneous perforators piercing the abdominal musculature in a plane 1.0-2.5 cm above the iliac crest. The row of perforators initiate at the Perforating branch of
The surgery is initiated with the patient in the supine position with a small role situated under the distal lumbar region. After routine skin preparation and draping, the femoral pulse is identified and a vertical incision (approximately 5 cm) is fashioned over the femoral vessels and extended cephalad to a point approximately 2 cm above the inguinal ligament. The incision is then curved laterally, pursuing an oblique course to the ASIS. The completed incision resembles a reverse L with the long limb parallel to the inguinal ligament. After completion of the skin incision, attention is redirected to the infrainguinal region. Blunt dissection is used Dominant perforating branch
a,
iac a.
anch
Fig 4. The DCIA liberating a series of small musculocutaneous perforators (0,3-0,5 mm) as it courses along the iliac crest, These vessels pierce the abdominal muscles approximately I cm above the lilac crest to supply the overlying skin. This is the predominant pattern of blood supply to the skin, ILIAC CREST MICROSURGICAL FREE FLAP
TECHNIQUE
ra.
iliac a. ranch
Fig 5, The dominant direct cutaneous artery (piercing branch) of the DCIA. An axial pattern skin island can be elevated on this vessel and its venae comitantes, The dominant piercing branch is present in approximately 30% of cases and is on average 1,5 mm in diameter and 6 cm in length,
291
to expose the femoral sheath. The sheath is not violated but provides a landmark for the more cephalad dissection. The suprainguinal dissection is initiated approximately 2 to 3 cm above the inguinal ligament in line with the lateral margin of the femoral sheath. A clamp is employed to spread the fascia of the anterior abdominal wall, exposing the origin of the DCIA and veins at the external iliac vessels in the preperitoneal space. The internal ring and spermatic cord should lie inferomedial. The fascia of the anterior abdominal wall and more lateral musculature is incised parallel to the inguinal ligament to a point several centimeters medial to the ASIS. The fascia is reflected, exposing the deep circumflex iliac vessels running above the iliacus muscle en route to the iliac crest. The vessels are freed from their connective tissue attachments using tenotomy scissors. If the reconstruction requires a section of internal oblique muscle, great care is exercised at this stage of the dissection because the origin of the DCIA can be variable. Typically, the ascending branch to the internal oblique takes off from the DCIA approximately 1 cm proximal to the ASIS. However, intermittently, one will find the vessels originating as far proximal as the external iliac.23 The region of internal oblique to be harvested is now outlined, but its elevation is deferred until dissection of the cutaneous island is completed. If a cutaneous paddle is necessary, its dissection is begun at this point. The technique employed is determined by the requirements of the reconstruction.
Technique 1 When bulky, soft tissue fill is required or neotongue reconstruction is contemplated, the traditional technique is
Fig 7. Flap explored and split.
used. 26A skin ellipse, up to 10 • 15 cm, is marked out over the midiliac crest, and the dissection is begun along the superior border of the flap and carried down to the external oblique muscle. The skin, subcutaneous tissue, and fascia are elevated en bloc with the intention of safeguarding the musculocutaneous perforators to the skin. The dissection is continued inferiorly in this plane and is terminated several centimeters above the iliac crest. The row of cutaneous perforators traverse the abdominal wall approximately 1 cm above the iliac crest. To ensure their preservation, the abdominal wall musculature is incised approximately 2.5 cm above the iliac crest to house the vessels in a "protective cuff" of muscle. 27 Attention is now focused on the inferior portion of the skin island. The dissection is resumed in the same plane and continued cephalad up to the superior pole of the iliac crest. A common approach is then followed to elevate the osseous component.
Technique 2 If a thin, axial-pattern skin flap is desired, an alternate technique is used. Again, a skin-soft tissue island, up to 10 • 15 cm, is elevated over the midiliac region from superior-to-inferior. The incision is initiated along the superior border and extended down to the external oblique
Fig 6. Mandibular defect.
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Fig 8. Flap dissected and raised. SHENAQ ET AL
ing the initial o s t e o t o m y d o w n to the anterior inferior iliac spine, a n d incorporating the ASIS into the b o n e graft p r o d u c e s a b o n y s e g m e n t that can be inverted to simulate the m a n d i b u l a r angle and r a m u s (Fig 6 and 7). The vascular pedicle exits b e h i n d the n e w l y fashioned angle and is usually sufficient for microvascular anastomosis (artery, 1.5-2.5 m m ; vein, 2.5-3.0 mm). 1 The 8- to 10-cm pedicle length w a r r a n t s unfettered access to the external carotid system. The b o n e s e g m e n t is freed b u t the nutrient vessels are not ligated until the time of actual transfer (Fig 8 a n d 9). A careful, layered closure of the d o n o r site is then p u r s u e d . The residual internal oblique muscle is fixed to the p e r i o s t e u m of the iliac crest w i t h heavy, interrupted, proline sutures a n d the external oblique is anchored to the outer cortex of the iliac crest. Drill holes for suture fixation h a v e not been required. Several closed suction drains are placed t h r o u g h the adjacent skin, a n d Scarpa's fascia a n d skin are closed in the usual layered fashion. O n the third p o s t o p e r a t i v e d a y a p r o g r a m of progressive a m b u l a t i o n is initiated.
REFERENCES
Fig 9. (A) Flap inset,(B) Fixated withmandibular reconstruction plate, fascia. The dissection continues inferiorly in this plane, a n d great care is taken to skeletonize a n d preserve the r o w of skin perforators. If a d o m i n a n t p e r f o r a t o r (piercing branch) is identified, the residue of the skin flap is elevated, a n d the accessory perforators are serially ligated while clinically m o n i t o r i n g flap perfusion. The process is continued until the skin island exists as axial pattern, cutaneous flap p e r f u s e d solely b y the d o m i n a n t piercing b r a n c h of the DCIA. The dissection then proceeds t h r o u g h the a b d o m i nal muscles p r e s e r v i n g a 1-cm m u s c u l a r collar a r o u n d the piercing branch. After isolating the piercing branch, the insertion of the a b d o m i n a l muscles is freed f r o m the iliac crest to expose the u n d e r l y i n g fossa. The skin island can n o w be conservatively defatted w i t h o u t complication. H a r v e s t i n g of the osseous c o m p o n e n t is not influenced b y the m e t h o d of cutaneous elevation. The p e r i o s t i u m is incised along the superior pole of the iliac crest a n d reflected f r o m the midline. If required, the p a d d l e of internal oblique is h a r v e s t e d at this time. Now, the iliacus muscle is reflected to expose the m e d i a l cortex, a n d the osteotomies begin. Initially, a sagittal s a w is e m p l o y e d to bisect the ilium to establish cortical independence. Subsequent transverse a n d posterior osteotomies d e t e r m i n e the height a n d length of the n e o m a n d i b l e respectively. ExtendILIAC CREST MICROSURGICAL FREE FLAP
1. Swartz WM, Banis JC: Flaps from the groin, in: Head and Neck Surgery. Baltimore, ME),Williams and Wilkins, 1992, pp 62-72 2. Shenaq SM, Klebuc MJ: The iliac crest microsurgical free flap in mandible reconstruction. Clin Plast Surg 21:37-43,1994 3. Urken ML, Vickery C, Weinberg H, et al: The internal oblique-iliac crest osseomyocutaneous free flap in oromandibular reconstruction. Arch Otolaryngol Head Neck Surg 115:339-349, 1989 4. Shenaq SM, Klebuc MJ: TMJ reconstruction during vascularized bone graft transfer to the mandible. Microsurgery 15:299-304, 1994 5. Matloub HS, Larson DL, Kuhn JC, et al: Lateral arm free flap in oral cavity reconstruction: A functional evaluation. Head Neck 11:205-211, 1989 6. Urken ML, Weinberg H, Vickery C, et al: The neurofasciocutaneous radial forearm flap in head and neck reconstruction: A preliminary report. Laryngoscopy 100:161-173,1990 7. Obeid G, Guttenberg SA, Connole PW: Costochondral grafting in condylar replacement and mandibular reconstruction. J Oral Maxillofac Surg 48:177-182,1988 8. Schusterman MA, Reece GP, Kroll SS, et al: Use of the AO plate for immediate mandibular reconstruction in cancer patients. Plast Reconstr Surg 88:588-593, 1991 9. Kloch DW, Prein J: Mandibular reconstruction using AO plates. Am J Surg 154:384-388,1987 10. Riediger D: Restoration of masticatory function by microsurgically revascularized iliac crest bone grafts using enosseous implants. Plast Reconstr Surg 81:861-876, 1988 11. Wenig BL, Keller AJ: Rigid internal fixation and vascularized bone grafting in mandibular reconstruction. Clin Plast Surg 16:125-131, 1989 12. Sanger JR, Head MD, Matloub HS: Enhancement of rehabilitation by use of implantable adjuncts with vascularized bone grafts for mandible reconstruction. Am J Surg 156:243-247, 1988 13. Shenaq SA: Split-inner cortex iliac crest microsurgical free flap: A new refinement for mandibular reconstruction. Presented at the American Association of Plastic Surgeons Meeting, San Antonio, TX, April 14-17, 1991 14. Kuriloff DB, Sullivan MJ: Mandibular reconstruction using vascularized bone grafts. Otolaryngol Clin North Am 24:1391-1418,1991 15. Safak T, Klebuc MJ, Shenaq SM: New concepts in fascioucutaneous flaps. Plastic Surgical Forum, ASPRS Meeting, San Diego, CA, 1994 16. Safak T, Klebuc MJ, Shenaq SM, et al: New concepts in fasciocutaneous flaps. Plastic Surgery Educational Foundation Scholarship Contest, 1st paper for Junior Clinical Research Award, 1994 17. Manchester W: Some technical improvements in the reconstruction of the mandible and temporomandibular joint. Plast Reconstr Surg 50:249-256, 1972
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18. Harii K, Ohmori K, Toril S, et al: Free groin skin flaps. Br J Plast Surg 19.
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28:225-237,1975 Taylor GI: Reconstruction of the mandible with free composite iliac bone graft. Ann Plast Surg 9:361-376, 1982 Safak T, Klebuc MJ, Kecik A: Closure of upper extremity soft tissue defects using the new "supra-crest" fasciocutaneous free flap. Plast Reconstr Surg (in press) Taylor IG, Palmer JH: The vascular territories (angiosoms) of the body: Experimental study and clinical applications. Br J Plast Surg 40:113-117,1987 Hartrampf CR, Noel TR, Orazon L: Ruben's fat pad for breast reconstruction: A peri-iliac soft tissue free flap. Plast Reconstr Surg 93:402-404, 1994
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23. Ramasastry SS, Granick MS, Futrell JW: Clinical anatomy of the internal oblique muscle. J Reconstr Microsurgery 2:117-122,1986 24. Urken ML: Composite free flaps in oromandibular reconstruction. Arch Otolaryngol Head Neck Surg 117:724-732, 1991 25. Taylor GI, Corlett RJ: Microvascular free transfer of a compound deep circumflex groin and iliac crest flap to the mandible, in Strauch B, Vasconez LO, Hall-Findlay EJ (eds): Grabb's Encyclopedia of Flaps (Vol 1). Boston, MA, Little Brown, 1990, pp 589-599 26. Salibian AH, Rappaport L Allison G: Functional oromandibular reconstruction with the microvascular composite groin flap. Plast Reconstr Surg 76:819-828, 1985 27. Daniel RK: Mandibular reconstruction with free tissue transfers. Ann Plast Surg 1:348-367,1978
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