Acquired Chest Deformities

1 Lip Teh Januray 2006

ACQUIRED CHEST DEFORMITIES

INTRODUCTION Functions of Chest Wall 1. Hard shell for protection of vital structures: heart, lungs, liver, spleen, kidneys, pancreas. 2. Flexible frame for respiratory movement.

Aetiology 1) Tumour (primary or recurrent) 2) Infection 3) Radiation injury 4) Trauma 5) Surgery (Postpneumonectomy empyema, Post sternotomy dehiscence)  Secondary to devascularisation and infection

CONSIDERATIONS 1. Soft tissue coverage  Infection – sternal osteomyelitis  Irradiated tissues 2. Skeletal stabilisation  Visceral protection  Respiratory function 3. Obliteration of dead space  Chronic empyema cavity  Broncho-pleural fistula 4. Aesthetic contour corrections

Unlike congenital defects where indications are essentially cosmetic, requirements in acquired chest wall reconstruction are: 1. Function 2. Durability, resistance to infection 3. Aesthetics 2 Lip Teh Januray 2006

RESPIRATORY PHYSIOLOGY  Inspiration – active process involving diaphragm (primary) and accessory muscles  Expiration – passive process with intrinsic elasticity of the lung and musculature.  Flail chest occurs when a segment of chest wall becomes independent resulting in a paradoxic respiratory pattern and inefficient ventilation (on inspiration, flail segment gets sucked in). Not evident when patient is positively ventilated.  Generally defects less than 5 cm in diameter or resection of 3 ribs or fewer do not merit skeletal stabilization.  Physiologic deficit is minimal with loss of the upper sternal body and associated ribs, is moderate with loss of the entire sternal body and associated ribs, and is severe with loss of the manubrium and upper sternal body and associated ribs.

PRINCIPLES OF CHEST WALL RECONSTRUCTION 1. Early Debridement and resection  Remove devitalised bone and cartilage to healthy margins (whether for trauma, tumour or radiation necrosis).  Even well vascularised muscle flaps cannot be placed on a wound that has not been properly debrided.  With the currently available flaps, debridement should not be limited for fear of being unable to attain closure.  However advantageous if one can preserve the lateral edge of the sternum during a partial sternectomy - stability of the medial ends of the ribs and costal cartilages is maintained, reducing the incidence of early postoperative clicking and discomfort when these structures are allowed to float free  Eradication of infection and necrotic tissue is the key to success.  The greater the delay between debridement and final muscle flap closure, the greater the risk of desiccation and rupture of vital structures, particularly coronary grafts and the right ventricular wall, even in the face of daily wet dressing changes in the operating room.  Sudden changes in intrathoracic pressure induced by coughing may cause ventricular rupture and exsanguination if the venticle and adjacent tissues have become adherent to the posterior aspect of the ribs anteriorly, and the longer the chest is left open, the greater this risk becomes

2. Obliteration of dead space and broncho-pleural fistula  Problems encountered following lobectomies and pneumoectomies: a)Bronchopleural fistula 3 Lip Teh Januray 2006

b) Empyema c)Dead space  Usually the tissues are pliable and the void is filled by lung expansion, shift of surrounding soft tissues (including the mediastinum) and elevation of the diaphragm aided by negative suction drainage.  Tissues may lose their pliability with chronic inflammation, radiation, etc and thus not have the ability to fill dead space. In these cases, obliteration of the cavity can be achieved by: 1) exteriorising the cavity (Eloesser procedure) 2) surgically collapsing the rib cage (thoracoplasty)  reserved for when pedicled muscle flaps are unavailable or when the empyema is chronic and caused by antibiotic-resistant organisms.  the resection of multiple ribs to allow the collapse of the chest wall and obliterate the cavity 3) filling the cavity with soft tissue: omentum or muscle  The first 2 options, although functional, give grotesque cosmetic results and therefore the third option is the best.  Miller single stage protocol(Ann Thorac Surg 1984): 1) entry into the chest through the original incision 2) wide debridement 3) identification of bronchopleural fistulas - closure with an omental flap 4) obliteration of the pleural cavity with muscle flaps starting with the LDM first, SAM second, PMM third, omentum fourth, and the RAM as the last choice.  Arnold and Pairolero (Ann Surg 1990) 1) open debridement and muscle-flap transposition 2) dressing changes thru an open window thoracostomy until the wound exhibited healthy granulation tissue. 3) if the thoracic cavity was small, it was filled with an additional muscle transfer; if it was large, the thoracic cavity was filled with an antibiotic solution and closed(Clagett procedure) 4) no attempt made to fill a large empyema cavity with autogenous tissue. 5) overall success rate in closure of the cavity was 84 percent and closure of the bronchopleural fistula 86 percent.  Arnold and Pairolero (PRS 1996)  One stage preferred in acute settings  But wound often chronic on consultation  In this setting, best to undergo multiple debridements/dressings until the wound shows healthy healing 4 Lip Teh Januray 2006

 Often able to downgrade the size of the wound  Workhorse flaps are Pec major and lat dorsi  Backup flaps are rectus abdominis (less reliable) and omentum – can’t use if no skeletal barrier between thorax and skin  Michaels and Probaz PRS 1997 1) removal of infected and necrotic tissue using sharp debridement and pulsed lavage 2) repair of bronchopleural fistulas with muscle flaps 3) minimization of the dead space with combinations of muscle flaps and thoracoplasty.

3. Skeletal reconstruction  Aim: to restore pulmonary mechanics and for visceral protection  The decision as to whether skeletal support is required is based on: 1. The general condition of the patient, especially respiratory compromised or not. 2. The underlying wound. RT damage, for instance, causes stiffness and less requirement for skeletal support. 3. The site and size of the defect a) site: posterior defects, eg related to scapula, even if large, may not require skeletal support. Sternal loss, if it is complete or involves the keystone area of the manubrial-body junction, usually will require support. b) size: Dingman, Arnold: loss of 4 or more ribs will require skeletal reconstruction. Size of defect therefore depends not only on the number of ribs missing, but also the length of rib or bone missing.  Options c) Autograft  bone graft : ribs, iliac, fibula, tibia  Ribs can be transferred as free grafts (may resorb), pedicled on serratus or other muscle flap, pedicled on periosteum or pedicled on intercostal vessels. They can be cut obliquely and angled up to the space above, or down to the space below. Split rib grafts have have the advantage of leaving a better donor site and preserving stability  fascia: prone to infection, predictable instability secondary to inherent flaccidity d) Allograft – revolutionised skeletal reconstruction  Options: Gore-Tex, Vicryl mesh, Marlex mesh, methylmethacrylate, titanium, acrylic 5 Lip Teh Januray 2006

 Chang (Ann Plast Surg 2004: Memorial Sloan) – Marlex mesh for defects <4 ribs, otherwise Marlex mesh and methymethacrylate as a sandwich. Marlex mesh has a tendency to fragment, combining it with methyl methacrylate solves this problem  Gore-Tex often is preferred to Marlex by some because of its malleability, flexibility, durability, conformability, and impermeability.  Problems: infection, seroma, extrusion  When the wound is clean, prosthetic material is the first choice for skeletal replacement.  Only indication for autologous grafts is infection

4. Coverage  Semi-rigid skeletal frame renders soft tissue less mobile for use of local tissue for closure. Usually distant flaps required.  Rigidity of the chest wall makes wound contraction less effective and spontaneous closure is thus less likely.  Sternal coverage – local vs free flap options

6. Aesthetic considerations

7. Patients general condition  When considering reconstruction this is an important consideration, especially as many of these patients have or have had severe underlying disease and may be old and cruddy.  Smoking, sepsis, previous Ca or RT are all important.

Reconstruction must therefore take into account: 1. the status of the pleural cavity 2. the requirement for skeletal support 3. the soft tissue defect

AVAILABLE FLAPS Historical 6 Lip Teh Januray 2006

 Local flaps requiring multiple delays, tubed flaps, waltzed flaps, jump flaps (carried on the wrist), mobilisation of the opposite breast to cover chest wall deformities.  These flaps were of limited size, disfiguring, cumbersome, laborious and unsuccessful.  They may still have a place, however, for some defects (especially small) and as rescue manoeuvres when other flaps have failed.  Standard treatment for poststernotomy mediastinitis was debridement and closed catheter irrigation prior to flaps with a mortality of 20-40%.  The advent of flaps has reduced this to 5%  1957 – Julian introduced median sternotomy  1976 – Lee described use of the vascularized omentum to treat the mediastinal wound.  1980 - Jurkiewicz introduced sternal wound closure by muscle flap transposition.  1980s – Arnold and Pairolero (Mayo clinic) popularised intrathoracic transposition of extrathoracic skeletal muscles, mainly using latissimus dorsi, pectoralis major, serratus anterior, pec minor and rectus.

Fasciocutaneous flaps  Not ideal due to lack of bulk 1) Deltopectoral flap a. Deltopectoral fascial turnover flap, with dermal thickness skin based superiorly raised separately b. Useful to cover superior ½ of sternum only 2) Thoracoepigastic flap a. Based on subcostal artery 3) Scapular and parascapular flaps a. For axillary and lateral thoracic wall defects

Omental flap  dependable and versatile flap that allows coverage of virtually all chest wall defects based on either gastroepiploic vessels  arc of transposition extends 5 to 10 cm higher toward the chest when the omental flap is obtained from the left rather than the right gastroepiploic artery  final method of increasing flap length involves division of the gastroepiploic arch and reliance on Barkow's marginal artery as collateral circulation to maintain flap viability. 7 Lip Teh Januray 2006

 low morbidity and minimal deformity  At least two studies indicate that omentum provides better results than muscle flaps in terms of reducing mortality and eradicating infection. (PRS 1998; Ann Thoracic Surg 1999)  Where it is useful is for extensive radiation necrosis of mainly the superficial tissues which can be debrided to bone and covered with omentum and SSG.  Disadvantages 1) Needs laparotomy, bowel adhesions, injury – may be harvested endoscopically 2) Size variable, cant be predicted 3) obligatory epigastric hernia if the omentum is passed subcutaneously - risk of hernia formation reduced by splitting the diaphragm and passing the omentum through it

Muscle/myocutaneous flaps 1. Pectoralis major 2. Latissimus dorsi 3. Rectus abdominis Also; 4. External oblique 5. Serratus anterior 6. Trapezius

The first 3 are the mainstay because they are large, expendable, reliable with a good blood supply.

Pectoralis Major (Type 5)  Used as (a) turnover flap  unreliable if ipsilateral IMA is not present  If repeat median sternotomy required, this may de-vascularise the muscle.  wastes a lot of the muscle. (b) rotation-advancement pectoralis flap  based on thoracoacromial pedicle  often require bilateral pectoralis to cover whole sternal defects 8 Lip Teh Januray 2006

 Patients with total detachment of the pectoralis muscle do not demonstrate any measurable shoulder weakness. Any loss of upper body strength is mainly a result of sternal debridement and not muscle sacrifice.

Latissimus dorsi (Type 5)  useful for more lateral wounds  Can reach across the midline if the branches to serratus are ligated, the TD pedicle skeletonised, and the humeral insertion of the muscle is cut.  Even when the main pedicle has been cut (as in mastectomy), the muscle can still be raised and transferred on the serratus branch (May, 1982) - some distal necrosis may be expected  The subscapular artery not only supplies latissimus dorsi (via the TD), but also the serratus anterior and the scapula flaps. When needed, 2 or 3 components can be taken together (chimeric flap) to fill a large defect or one with specific requirements  The muscle can be split (the TD artery divides into two branches within the substance of the muscle)  minimal functional impairment is appreciated. Only forceful backward extension and adduction of the arm are noted as mildly-to-moderately compromised.

Rectus Abdominis (Type 3)  Can be used in a number of ways for chest wall reconstruction: 1. TRAM 2. With a vertical skin island (Dinner and Dowden, 1983) 3. As a turnover flap based on DSEA 4. As a free flap based on DIEA  When based on DSEA, good for covering lower ½ of sternum  May be used with superior pedicle even after ligation of ipsilateral IMA (Netscher Ann Plast Surg 2001) - collateral circulation to the superior epigastric vascular pedicle through the musculophrenic artery as well as through the lower intercostal arteries (costomarginal arteries)  Incorporation of a skin island improves the venous drainage (Carramenga e Costa, PRS 79: 214, 1987. See also PRS 81: 721, 1988).  The choke vessels between the DSEA and the DIEA lie above the umbilicus, between it and the costal margin 9 Lip Teh Januray 2006

 The DIEA is haemodynamically dominant (based on intra-op pressure studies done by Shaw and Feng, 1988), thus free flaps should be based on the DIEA. Basing the free flap on the DIEA also has the advantage that less muscle needs to be taken and the functional deficit is thus less.  Main drawback is risk of hernia

Serratus Anterior (Type 3)  Lower 4 slips harvested  Usually used as an intra-thoracic filler for problems in the chest or small defects in the chest wall  Can also be used with latissimus dorsi to bring more tissue to the front of the chest than latissimus dorsi can supply on its own.  Minimal donor site morbidity

External Oblique (Type 4)  Not often used although useful for antero-lateral defects below the IMC.  Can be used as a V-Y  Can be used to reconstruct the diaphragm.

FREE FLAPS  Useful in the unusual event that regional flaps are not available (d/t previous surgery or RT) or when the defect is very large.  Regional muscle flaps tend to waste a large part of the pedicle in allowing transposition, whereas free flap usually do not.  With 95% mean survival (Shaw, 1983), the indications have broadened. Advantages: 1) less functional loss and donor site morbidity 2) allow versatility of reconstruction 3) often achieve a better aesthetic result

 Special problems exist, however, in the transfer of free flaps for chest reconstruction. 10 Lip Teh Januray 2006

Donor sites  For chest reconstruction, flap should usually be bulky with a large surface area and thick.  The ability to include bone or fascia may be advantageous.  Options: 1) contralateral latissimus dorsi 2) rectus abdominis (based on DIEA) 3) TFL (can incorporate rectus femoris)  Donor site located at a distance allows 2 teams to operate and reduces the risk of post-op respiratory compromise.

Recipient vessels Ideally should meet the following criteria: 1) Reasonable calibre (1.5-2.5 mm) 2) Outside the zone of injury 3) Easily accessible 4) Anatomically consistent 5) Potentially dispensable 6) Conveniently located near the defect

 Usually located in the axilla, neck or mediastinum. 1) Axillary: subscapular, thoracodorsal, thoraco-acromial 2) Neck: transverse cervical 3) Mediastinum: internal mammary. Intercostals usually too small and difficult.

PMOFR Protocol at Monash (Alvarez PRS 2002)  immediate debridement in the presence of clinical sternal wound infection  opened sternotomy was irrigated with 2 liters of saline twice daily and packed with 10% alcoholic povidone-iodine saturated sponges  Based only on the clinical appearance of a clean wound 2 to 4 days later, a PMOFR was performed.  Both pectoralis major muscles were dissected from the sternal margins for 14 to 20 cm as myocutaneous flaps without release of humeral insertion 11 Lip Teh Januray 2006

 The sternotomy was extended into a laparotomy, and a tongue of greater omentum, based on an arcade of gastroepiploic branches, was delivered to cover the entire mediastinum.  Compared to traditional management (sternal debridement, rewiring, and closed drainage, with or without antibiotic saline tube irrigation): . Major complications – 22 vs 92% . ICU readmission – 0 vs 58% . Total length of stay – 32 vs 79 days . 30 day mortality – 0 vs 33% . Free of infection at 2 years – 100% vs 12%