Reconstruction of complex chest wall defects

Reconstruction

of Complex

Mimis Cohen, MD, FACS, Sai S. Ramasastry,

BACKGROUND: Reconstruction of complex chest wall defects represents a major challenge and requires close cooperation between the cardiothoracic and reconstructive surgeon to achieve an optimal outcome and reduce the incidence of complications. The principles of chest wall reconstruction include control of infection, local wound care, wide debridement of all necrotic and devitalalized tissues, obliteration of all residual cavities and spaces with well-vascularized tissues, reestablishment, when necessary, of the continuity and skeletal stability of the chest wall, and immediate or early definitive coverage of all defects with well-vascularized tissues. METHODS: This paper is based on our experience with 113 patients who underwent chest wall reconstruction for a variety of defects resulting from infection, trauma, tumor extirpation, and radionecrosis. All patients were treated with a variety of muscle flaps and/or omentum which provided obliteration of dead space and coverage. Seven patients with large anterolateral defects required additional skeletal stability with synthetic patches or mesh. RESULTS: 88.6% of patients healed without significant problems. 8.8% had major complications requiring reoperation and prolonged hospitalization while 4.4% had minor complications. CONCLUSIONS: Based on long-term experience, we believe that currently the use of well-vascularized tissue is the method of choice for reconstruction of complex chest wall defects. This provides stable coverage, reduces hospital stay, and thus lowers overall care cost for these patients. Am J Surg. 1996;172:35-40.

econslruction of complex chest wall defects represents a great challenge and requires close cooperation between the reconstructive and the cardiothoracic surgeon to achieve an optimal outcome and reduce the incidence of complications. Chest wall defects result primarily from infection, ablative surgery, radiation damage, and trauma. While superficial defects involving only the soft tissues of the trunk, without exposure of bone, cartilage, or vital structures are relatively simple to manage and can be treated successfully with skin grafts or local pedicle flaps, full thickness defects with exposure of bone and cartilage,

R

From the Divisions of Plastic Surgery, University of Illinois and Cook County Hospital, Chicago, Illinois. Requests for reprints should be addressed to Mimis Cohen, MD, University of Illinois at Chicago, Department of Surgery M/C 958, Suite 515 CSN, 820 S. Wood Street, Chicago, Illinois 60612-7316.

0 1996 by Excerpta All rights reserved.

Medica,

Inc.

Chest

Wall

Defects

MD, FRCS, Chicago, lhois

or even exposure of vital structures such as lung, heart, or great vessels present with different reconstructive requirements, in order to obtain the best possible functional as well as aesthetic results. With extensive understanding of the vascular anatomy of the muscles and omentum during the last two decades and the establishment of musculocutaneous units, use of muscles, musculocutaneous, or omental flaps have become well accepted procedures used widely for reconstructive purposes. l-3 The availability of these flaps has given the surgeon the chance to undertake wide resection of malignant tumors which would have been considered “unresectable” in the past and to proceed with a wide debridement of devitalized or infected soft tissues and cartilage or bone prior to the reconstruction. This type of debridement is essential and a prerequisite for a successful and stable long-term coverage of defects resulting from radiation damage or infection.4 This paper is based on a combined experience of 113 patients who underwent chest wall reconstruction over the last 12 years for a variety of defects resulting from infection and dehiscence of median sternotomy wounds after cardiac surgery, resection of radionecrotic tissues after radiation for malignant tumors, trauma due primarily to firearms, resection of tumors with primary reconstruction, and obliteration of chronic intrathoracic cavities (Table 1).

PRINCIPLES OF CHEST RECONSTRUCTION

WALL

The reconstructive principles for management of defects of the chest wall are well established and are similar to the principles established for defects in other areas of the body. The surgeon should meticulously follow these principles prior to any reconstructive procedure: 1) Control of infection with appropriate culture-specific antibiotics. 2) Local wound care. 3) Wide debridement of all necrotic and devitalized soft tissues, cartilage, or bone. 4) Removal of all foreign bodies from the wound. Following these basic measures, the surgeon should proceed with the following principles which pertain specifically to the chest wall area: 1) Obliteration of all residual cavities and spaces with well-vascularized tissues. 2) Reestablishment, when deemed appropriate, of the continuity and skeletal stability of the chest wall. 3) Immediate or early definitive coverage of all defects with well-vascularized tissues, including muscles or omenturn. Before proceeding with the reconstruction, the surgeon should have a detailed knowledge of all previous procedures in the area. An extensive clinical evaluation is also neces0002-961 O/96/$1 PII SOOO2-9610(96)00058-X

5.00

35

R ECONSTRUCTION TABLE

OF CHEST

WALL

DEFECTS/COHEN

AND

I Patient

Location Defect

of

No. of Cases

Etiology

Reconstruction pectoralis major, rectus abdominis, omentum

1 1 6 3 3

6

radionecrosis

2 13

tumor radionecrosis

pectoralis major, rectus abdominis pectoralis major latissimus dorsi, rectus abdominis, omentum (mesh or Patch #6) latissimus dorsi (Patch #l) latissimus dorsi reverse latissimus dorsi trapezius paraspinous

1 partial wound dehiscence none 1 partial wound dehiscence

trapezius

62

Sternum

Anterolateral defects Posterolateral Posterolateral

tumor

Posterior midline Posterior midline Posterior midline lntrathoracic

postoperative infection radionecrosis

Total

Data

infection & dehiscence of median sternotomy for cardiac surgery

Sternum

Sternum Anterolateral defects

tumor trauma wound

Complications

tumor

latissimus

bronchopleural fistula Post-pneumonectomy

serratus anterior, latissimus dorsi, pectoralis major

dorsi

113

Tissue Available for Chest Wall Reconstruction A. Pectoralis major muscle. This broad muscle, because of its location in the anterior chest wall and its bulk, blood supply and arc of rotation, represents an excellent option for the reconstruction of anterior midline defects around the sternum and for intrathoracic transposition. The muscle can be based on its primary pedicle, the thoracoacromi~ll artery, or as a turnover flap, on its segmental blood supply from perforators of the internal mammary artery (Figure 1).jm7 THE

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cardiopulmonary hematoma drainage partial skin necrosis partial flap loss persistent sinus

1 death debridement & STSG additional muscle flap debridement of residual infected cartilage and rib all other patients healed with no problems healed wound healed healed

wound wound

none

healed

wound

none none

healed healed

wound wound

none

healed

wound

none

healed

wound

none

healed

wound

none

healed

wound

15 = 13.2%

sary to fully understand the reconstructive requirements of a given defect, and study the availability of various flaps. The chest wall is covered circumferentially with several paired muscles. Furthermore, the set of rectus abdominis muscles and the greater omentum are available to the reconstructive surgeon when needed. Because of this extensive availability of reconstrictive options, pedicle flaps are primarily used in this area. The use of free vascularised flaps is seldom necessary, in contrast with the reconstruction of defects in the head and neck area or the lower extremities where free flaps provide superior reconstruction in the majority of cases. The selection of the most appropriate flap is primarily dictated by the location and size of the defect, while other factors such as tissue availability due to previous procedures or surgeon’s preference also play a role in the final decision.

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B. Latissimus dorsi muscle. This broad back muscle hecause of its position, size, bulk, and arc of rotation represents the flap of choice for the reconstruction of anterior and lateral chest wall defects, based on its primary vascular supply, the thoracodorsal pedicle. Its use for intrathoracic defects is limited since it is usually transected by a previous thoracotomy, but the proximal part is useful in combination with other flaps. This muscle can also be used based as a turnover flap on its segmental blood supply from perforators of the intercostals and lumbar arteries. When based on these vessels, the muscle provides the best flap choice for coverage of defects of the lower pamspinal area (Figures 1 and 2).“-” C. Rectus abdominis muscle. This muscle flap based on the superior epigastric pedicle IS helpful in the reconstruction of midline or anterior-lateral defects of the chest wall. Furthermore, when used as a transverse rectus abdominis muscle (TRAM) flap design it can support a large skin island to provide coverage of extensive chest wall defects (Figures 1 and 3).“,” D. Trapezius muscle. This muscle based on the descending branch of the transverse cervical artery represents the flap of choice for coverage of defects of the posterior neck, upper pXdSpiIId1 area, and posterior midline. It can he used as a muscle or a musculocutaneous flap according to the requirements of the reconstruction (Figure Z).” JULY

1996

RECONSTRUCTION

Figure 1. Flaps available for the reconstruction of anterior midline and anterolateral defects. Pectoralis major based on the thoracoacromial pedicle; pectoralis major based on perforators of the internal mammary; serratus anterior and latissimus dorsi based on the thoracodorsal pedicle; greater omentum based on the right gastroepiploic pedicle; and rectus abdominis based on the deep superior epigastric pedicle.

E. Serratus anterior muscle. This muscle flap based primarily on the serratus branch of the thoracodorsal artery is primarily used for reconstruction of intrathoracic defects. Its use for the reconstruction of surface defects is quite limited due to its size, location, and arc of rotation (Figure l).” F. Paraspinous muscle. This muscle has a segmental blood supply from perforators arising from the dorsal segmental branch of the aorta. Thus, the muscle has a litnited arc of rotation but can be used for coverage of posterior midline thoracic defects (Figure 2). G. Omentum. The greater omentum flap based on the right or left gastroepiploic pedicle is a helpful flap in the reconstruction of anterior midline and lateral chest wall defects. Because of its supple texture, the omentum can be used to fill residual cavities, primarily in the mediastinum. Its rich lymphatic plexus greatly assists in the control of infection. However, because of the need for a laparotomy, the ever present risk of infection, and the availability of multiple muscle flaps, the omcntum is currently considered only when other options are not available (Figure l).“,” Skeletal Stability Large full thickness chest wall defects might produce skeletal instability that should be taken into consideration along with the individual patient’s pulmonary reserves and managed simultaneously with the soft tissue reconstruction when needed. There is no cconsensus in the literature about the size and location of defects that absolutely require reestablishment of the continuity of the bony framework. Rohust muscles or musculocutaneous flaps have been able to provide enough stability in most areas of the chest wall, thus reducing the need for additional stability. Bone grafts are seldom used. Certainly their use is absolutely contraTHE

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Figure 2. Flaps available for the reconstruction of back defects. Upper third: trapezius muscle based on the descending branch of the transverse cervical pedicle. Middle third: trapezius muscle and latissimus dorsi muscle based on the thoracodorsal pedicle. Lower third: reverse latissimus dorsi muscle based on perforators of the intercostals and lumbars.

Figure design

AMERICAN

3. Transverse rectus for the reconstruction JOURNAL

OF SURGERY”

abdominis of anterior VOLUME

musculocutaneous chest wail defects. 172

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flap

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IECONSTRUCTION TABLE

OF

CHEST

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II Flap Choice

Location

of Defect

First

Anterior midline Anterolateral chest Posterolateral Posterior Posterior

for Coverage

(upper) (lower)

defects

Serratus

AMERICAN

JOURNAL

anterior

SURGERY@)

VOLUME

Choice

m. omentum abdominis m. omentum

Free flap Latissimus dorsi Paraspinous m. Latissimus dorsi Latissimus dorsi Pectoralis major Rectus abdominis Omentum Thoracoplasty

omentum

BY LOCATION

OF

Defects Second

Anterior and Lateral Chest Wall Defects Defects in this area result mainly from primary or secondary tumor extirpation or from resection of radionecrotic areas. Superficial defects without exposure of cartilage, bone, or intrathoracic structures can be simply managed with skin grafts, local skin, fasciocutaneous or musculocutaneous flaps. Full thickness defects, however, with resection of ribs present more complex problems. Defects of up to two ribs can be reconstructed with muscle flaps only and will maintain good stability of the chest wall. Larger defects, on the other hand, might require reestablishment of the skeletal continuity prior to soft tissue reconstruction, particularly in patients with limited pulmonary reserves. We primarily favor the use of synthetic patches in this area and utilize a polytetrafluorosethylene ( PTFE-Gortex) patch to reestablish the continuity and stability of the bony framework of the chest. A 2-mm thick patch is usually sewn around the defect under maximal tension. The main advantage of this material over the synthetic or absorbable meshes is that it provides a complete separation of the thoracic cavity from the overlying soft tissues. Thus fluids from the pleural cavity are prevented from leaking under the soft tissues or muscle flaps. A chest tube is always placed to facilitate lung expansion and drainage of intrathoracic fluids. The flap of choice for reconstruction of defects in this area is the latissimus dorsi muscle or musculocutaneous flap. This muscle is mobilized based on its thoracodorsal pedicle and transposed to predictably cover large defects anterolateral defects with a high rate of success. Multiple drains need to be placed under the areas of dissection and the flap to prevent severe friction. A word of caution about the use of this muscle when the thoraco-dorsal artery has been divided during a previous procedure. In this event, the muscle can be still perfused through retrograde flow from the serratus anterior branch THE

Wall

Rectus abdominis Transverse recks

indicated in the presence of an infection while synthetic mesh, such as Marlex or Prolene, and patches, such as Gortex, ‘z have been used primarily for large, over three rib, defects of the anterior and lateral chest wall to provide stability of the skeletal framework prior to soft tissue reconstruction and coverage with musculocutaneous flaps or the omentum.‘H”9

RECONSTRUCTION

of Chest

Choice

Pectoralis major m. Latissimus dorsi m. Rectus abdominis m. Latissimus dorsi m. Trapezius m. Trapezius m. Reverse latissimus m.

chest midline midline

lntrathoracic

38

RAMASASTRY

172

m. m. with vein graft m. m. m.

pedicle

elongation

of the thoracodorsal artery via the intercostal system. As long as this communication is intact, one can safely transfer the latissimus dorsi muscle in selected patients. An alternative muscle flap for reconstruction of defects in the anterior lateral chest wall area is the rectus abdominis muscle flap which can be used with a vertical skin island overlying the muscle or as a TRAM flap design providing, in addition to the coverage, simultaneous breast reconstruction with autogenous tissue when needed. In the event that the superior epigastric artery has been damaged or ligated from a previous surgery, the TRAM flap cannot be used as a pedicled flap, but a short rectus abdominis muscle flap to the level of umbilicus can still be used receiving its blood supply from branches of the intercostals, musculophrenic, and costomarginal arteries. As an alternative, the TRAM flap could be used, if needed, as a free vascularized flap based on the deep inferior epigastric pedicle which is anastomosed with recipient vessels in the axilla or intercostals (Table II). Sternal Wounds Sternal wounds result primarily from infection and dehiscence of median sternotomy wounds. Tumor extirpation and resection of radionecrosis can also result in anterior midline defects. A median sternotomy is currently the most commonly performed incision for cardiac operations. The incidence of major wound complications after stenotomy is very low, occurring in 0.4 to 0.5% of patients, but represents a serious risk increasing the postoperative morbidity and mobility for patients already debilitated. In the past, large mediasternal wounds were left open after debridement and allowed to granulate over a period of several months. This approach, although relatively simple, has severe drawbacks since a long period of convalescence is required and the risk of an infection spreading to suture lines, grafts, and prosthetic material with subsequent bleeding, aneurysm formation, or clotting of grafts is ever present. The closed technique introduced by Shumaker and Mandelbaum was designed to overcome some of these problems. The success of this technique, however, is variable and most complications result from the residual mediastinal dead space, which remains incompletely drained and obliterated after sternal reapproximation.‘“-‘z Over the last 15 years, JULY

1996

RECONSTRUCTION

the use of muscle flaps and omentum have gained significant popularity in the management of these complex wounds. Debridement of all devitalized and infected soft tissues, cartilage, and bone is a prerequisite for success. No attempt is made for bone reapproximation in the area and, due to fibrosis and scarring, paradoxical movement of the mediastinal is not seen. The pectoralis major muscle, due to its size, location, and arc of rotation, is the muscle of choice for soft tissue coverage of mediastinal defects. This muscle flap can be based on the thoracoacromial pedicle or on segmental perforators of the internal mammary. One or two muscles are used depending on the size of the defect. The rectus abdominis muscle represents a good alternative choice while the greater omentum and the latissimus dorsi muscle are only considered when the primary options are not available. In most cases the skin is approximated over the muscle flap and primary skin closure is obtained. In few cases, in order to avoid closure with undue tension, a skin graft is placed directly over the muscle flaps or the omenturn. Drains are always placed in the mediastinum and under the areas of flap mobilization (Table II). Posterior Defects Defects in the posterior chest wall are not as common as defects in the anterior and lateral areas. They are caused primarily by radiation necrosis, infection, trauma, and aftersurgical intervention. Upper and midthoracic posterior midline defects are primarily managed with the trapezius muscle. After extensive debridement of all devitalized tissues, the flap is mobilized as a muscle or musculocutaneous unit to fully obliterate the residual dead space and provide coverage to exposed dura, bone, or hardware. One muscle is usually sufficient but when additional bulk is necessary to achieve complete obliteration of dead space, a contralateral muscle should also be used. Lower midline and lateral defects are better managed with a reverse latissimus muscle flap. This flap is based on multiple intercostal and lutnbar perforators completely mobilized and transposed in the defect as a turnover muscle or tnusculocutaneous unit. The paired paraspinous muscles as a turnover bipedicle flap or as a superiorly based flap can be mobilized and used to cover midline defects.” In the unusual event that appropriate pedicle flaps are not available to cover defects of the lower midline due to radiation damage, trauma, or extensive debridement, the surgeon can still use the latissimus dorsi muscle after elongation of the thoracodorsal pedicle with vein grafts. This technique will allow mobilization and transposition of the latissimus dorsi tnuscle flap to the lower midthoracic and lumbar area. In all cases, meticulous hemostasis should be carried out prior to wound closure and judicious placement of drains should be considered in the areas of reconstruction and dissection (Table II). Intrathoracic Soft Tissue Transposition Soft tissue flaps have been used successfully in the management of various intrdthordcic conditions. Indications for intrathoracic soft tissue transposition include bronchopleural fistulas with or without empyema, erosion and leakage from the heart or great vessels, persistent airleaks, se-

OF CHEST

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DEFECTS/COHEN

AND

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1

quelae of intrathoracic irradiation and esophageal fistulas or perforations. Muscle flaps are used to reinforce bronchial stump closure, and suture lines to obliterate residual cavities. Most patients in this group had already undergone a thoracotomy which divides the latissimus dorsi muscle. Thus, in these cases the serratus anterior muscle is primarily used for the reconstruction. If additional bulk is needed, the superior portion of the latissimus dorsi muscle as well as the pectoralis major muscle, or even the greater omentum arc available for transfer. A portion of rib needs to be resected to facilitate intrathoracic transposition of chest wall muscles. A limited thoracoplasty can also be used if a residual cavity cannot be obliterated with the muscle flaps. This procedure, however, is debilitating and creates a permanent deformity in the chest wall (Table II).

RESULTS The rate of success of these reconstruction procedures are very high as long as the surgeon carefully evaluates the patient, plans, and executes the procedure in a timely fashion. Most patients suffer from tnultiple medical conditions in addition to the wounds in the chest wall and should be managed carefully, recognizing that the margin of error is very limited. Fifteen patients ( 13.2%~) developed postoperative complications. Five (4.4%) had minor and 10 (8.8%) had major complications. Only one patient in our series died from cardiopulmonary complications during the immediate postoperative period and two additional patients with infected median stenototny died from uncontrolled sepsis. One patient developed a large hematotna requiring drainage (Table I). There was no complete flap loss in our series of patients but 6 patients required additional dehridement of necrotic skin and subsequent skin grafting; 3 patients required an additional muscle flap, while 3 others required reoperation for a persistent sinus which was due to inadequate initial debridement of underlying infected hone and cartilage. All other patients had a primary healing with restored function of the chest wall. Three patients who underwent resection of radionecrosis presented with ;I small dehiscence in the suture line without exposure of vital structures, which was allowed to heal without further inter\~ention.

CONCLUSION Based on long-term experience, and that of others, we believe that muscle flaps or omentum provide superior reconstruction and should be considered as the method of choice for coverage of complex defects in the chest wall area. There are several advantages from using autogenous tissue for the reconstruction of these complex defects: l Healthy, well-vascularized tissue with considerable bulk are mobilized from areas distant to the defect, the area of infection, trauma or radiation to cover chest wall wounds, obliterate residual dead spaces in the thoracic cavity, or the mediastinum. . Because of their superior vascularicy, these flaps assist in the elimination of residual local infection. l They provide adequate protection for the heart, great vessels and lungs. J

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ECONSTRUCTION

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They provide adequate coverage of bone grafts, meshes or patches and help stabilize the chest wall. l Because of their rich vascularity, they promote healing, thus reducing the need for,wound care, shortening the hospital stay and convalescent period, therefore, decreasing subsequent medical costs. The disadvantages of using muscle tlaps or omentum are: l The need for an additional lengthy procedure in already debilitated patients. l The potential donor site morbidity. l The possible functional loss of a muscle unit. These disadvantages are offset by the significant benefits from using such flaps. Close cooperation between the cardiothoracic surgeon and the plastic surgeon is required, as well as execution of the procedure after evaluation of the functional and aesthetic needs, to achieve the best possible results while reducing the potential for an unfavorable outcome. l

REFERENCES 1. Mathes SJ, Nahal F. Trunk. Postcrwr trunk. In: Climcal .4&s OJ~ and Musczdocurnnrous F&x. St. Louis: Moshy, lY79:9 1. 2. Mathes SJ. Nahai F. .4 systematic approach to tlap selection. In: CXnical Ap@utions for Muscle and Musculo-Cutaneous F&s. St. Louis: Mushy; 1982:34 1. 3. M&raw JB, Arnolil PG, eds. 1McCraw and Arnold’s Atlas o~fbluscle and Muscuioct~taneot~s Flaps, Norfolk, VA: Hampton Press; 1986. 4. Cohen M. Reconstruction <)f the chest wall. In: Cohen M, ed. Mastery ojj Plastrc St~rgery Boston, MA: Little Brown, Bostcrn, 1994:1248-1267. 5. Arnold PC;, b&ro PC. Use of pectorahs major mu& flap to repair defects of anterior chest wall. Plat Keconstr Surg. 1979;63:205. 6. Junkicwicz MJ, Bostwick J, Hester TR. Infected me&an bternotomy wounds: successful treatment by muscle flaps. Ann Swg. 1980;191:738. 7. Nahai F, MU&~ L, Bone 1DK, Batwick J 111. Pectoralis major muscle turnover flaps for closure of the infected sternot~xny waun,i with preservation of form anct function. I’last Reconstr Sur~ 1982;7@:471. 8. McGraw JR, Penix JO, Baker JW. Repair of major &fects vi the chest wall anil spme with the latissimus dorai myocutaneous fl+. l’last Rrconscr Surg. 1978;62:197. Mzrsck

40

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9. Hmes GL, Lee G. Oste~,radi~)necr,,sia I,f the chest wall: Manaycmcnt elf lpoht-resectmn detects uslni: M&x mesh anil a rotated latiooimus ciorsl mywzutane~w ilap. Aln Smrg. 1983;49:608. 10. Lars(xl L)L, McMurtrey MJ. 11 owe J, et aL. Major chat wall reconstruction after chest wall irracliatl~m. Cheer. 1982;49:1286. 11. Stevenvw TR, Rtrhrich RJ, P~cls. Plnst Rxonstl- Surx I YX8;81:8 3 1. 16. Jurkirwicz MJ, Arnold PG. Tt 3~ ~)mc’nrum: an account of its use in thv reconstruction ,>i the chest wall. Ann Surg. lY80;185:54& 17. Miller l)W, Johnson 111). Omenr,rl graft m the management of infected ;r\cenLling acvtlc prosthese,. Ann Thorac Surfi. 1987;44: 614. 18. Grah,m~ J, Usher FC, P cnny JL. et al. Mxlw mesh as a prosthesis in the repair of thorxic wall clcfects. Ann Surg. 1966;151: 469. 19. McGraw JB. Penlx JO, B,,kcr JW. Pepair of major defects of the chest wall .m,l spine with the Lltlsslmw ,iorai myocutaneous tlap. PILIst Kecmw SW& 1978;62:197. 20. Schumacker HA, Mandelhau~n 1. C~x~tinuoua antibiotic lrrigation in the trt’atment of infectiL)n. Arc11 St4rg. 1963;86:384. 21. Glick PL, Guglielrntr HG, Tr,mbaugh R, Turley K. Iodine toxiclty in a patlent treated by continuh,ry;l\t,l M, Ginsberg G, LeSavoy MA. A new pxaspinous muscle tlap, 1%~ Surg Forum XVI. 1993;56.

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1