How I do .... a Pectus Repair
Aetiology
Syndromes
- Excavatum
- Carinatum
- Mixed
- Kyphoscoliosis-related
- Polands syndrome
- Sternal agenesis
Natural history and timing of surgery
Indications for operation
Operation
- Anaesthesia
- Equipment
- Incision
- Muscle flaps
- Sub peri-chondrial resection
- Neuro-vascular bundle release
- Osteotomy
- Fixation
- Drains
- Closure
- Postoperative care
Other procedures
- Weights/suspension
- Turnover
- Peri-chondrial sling
- Nuss procedure
Further reading:
Surgical Treatment of Anterior Chest Wall deformities, Chest Surgery Clinics of North America, May 2000, 261 - 276
Aetiology
The actual cause of pectus deformities is unknown. The usual explanation, for which there is some experimental evidence, is that there is overgrowth of the costal cartilages resulting in either protrusion or intrusion of the sternal elements.
Syndromes
Pectus excavatum (funnel chest)
Pectus excavatum occurs when the cartilage overgrowth results in the sternal manubrium being forced back towards the vertebrae. It is more common in males and frequently runs in families.
Pectus excavatum occurs when the cartilage overgrowth results in the sternal manubrium being forced back towards the vertebrae. It is more common in males and frequently runs in families.
In severe cases the xiphisternum virtually touches the vertebrae, displacing the heart laterally, usually to the left. The excavatum deformity behaves as though there are attachments to the tendinous diaphragm and even the vertebrae. As the child grows around this attachment, the sternum and cartilages are drawn in. Eventually the ends of the ribs are drawn in and the chest cavity becomes elongated and flattened. The clavicular heads are drawn in when the deformity is severe. The appearance is of a tall thin male with a flattened elongated chest and a concavity at the lower end of the manubrium.
Patients are often referred because of their associated asthma, the deformity being blamed for the respiratory effects. There is no evidence that it does. Others fear pressure on the heart. Again the evidence is rather poor for any cardiac compromise, many a pectus patient being well able to run a marathon. There is some evidence that severe deformities may impede right atrial filling at maximal exertion. As the heart is rotated to the left in severe deformities, right axis deviation and tall P waves can be seen in lead II.
Pectus carinatum (pigeon chest)
Pectus carinatum is thought to have a similar aetiology to excavatum. However, there is no similarity to the diaphragmatic adhesion. As parents do not fear cardiac compression minor deformities are often well tolerated. As breast development progresses normally girls often do not mind a mild carinatum deformity.
Mixed excavatum/carinatum
To be truthful virtually all deformities are mixed to a degree with some rotation of the sternum. It should be expected and not regarded as a difficulty. Frequently the rotation is so slight it is best left alone. More extensive rotation will need to be corrected with imaginative osteotomies and wedges.
Kypho-scoliosis associated
Pectus-like chest wall deformities often accompany Kypho-scoliosis. The deformity is usually unilateral and carinatum in nature. It is usually secondary to the vertebral rotation and is a rib deformity rather than a cartilage deformity. The deformity is exacerbated by the need for the lung to find some volume in which to operate. Therefore, any attempt to correct the deformity tends to fail as the lung re-expands and pushes the chest wall back out. To correct the deformity, rib osteotomies would need to be performed. This is virtually impossible to perform in flat bones.
Polands syndrome
Polands syndrome is a more extensive syndrome of defects of the chest wall. It includes loss of pectoralis major or minor muscles, hypogenesis or absence of the breast, absence of mammary and axilary hair, absence of costal cartilages and failure of the ribs to grow. Correction involves a combined procedure with the thoracic surgeon re-construcing the chest wall while the plastic surgeon performs an augmentation mammoplasty with latissimus muscle myocutaneous flap. The procedure must therefore be performed when growth is complete.
Agenesis of the sternum
Various degrees of sternal agenesis can occur with varying degrees of cardiac herniation. It is a rare congenital condition associated with craniofacial haemangiomata and omphalocele. It should be corrected in the neonatal period when the two halves of the sternum can usually be sutured together. Usually there are residual cartilaginous sternal bars connecting the rib ends.
In older children it may be necessary to perform slide chondroplasty accompanied by longitudinal osteotomies of the sternal bars to bring the two halves together. Skin cover may require omental or pectoral flaps. (See Cleft sternum and Sternal Foramen. Alexander A Forkin. In Surgical Treatment of Anterior Chest Wall deformities, Chest Surgery Clinics of North America, May 2000, 261 - 276)
Natural history and timing of surgery
If left unoperated the deformity increases in size, most markedly in the years of the pubertal growth spurt. As it becomes more severe, the rib ends are drawn in and the deformity of the ribs becomes permanent if correction is not performed before growth finishes. Many clinicians leave surgery till growth has stopped, hoping they will grow out of the deformity or that muscle growth will obscure it. Neither is the case in truth. At this stage the rib deformity cannot be corrected and the results cannot be satisfactory.
Young children are hardly aware of the diagnosis and have no interest in having it corrected. The easily embarrassed teenager however, will avoid taking his shirt off and will avoid swimming, changing in front of his mates for football and so on. In his late teens the self-conscious youth will be embarrassed by his appearance when dealing with the fairer sex.
There is no need to operate on the pre-school child when he is exposed to all the paediatric anaesthetic risks. I usually operate at about 8 years of age when anaesthesia is safer, there is plenty of time for the deformed ribs to refashion themselves and a few weeks off school will not affect his academic progress. At this stage the deformity is mild and he is usually not worried by the condition. However, at this age he is still not conscious of the deformity, though his parents may be, and it will be difficult to convince him that, by the time he is conscious of it (at age 15) it will be too late to get a good result. This then is the dilemma facing the advising surgeon.
Indications for operation
The indication for the operation is cosmesis. It is a cosmetic operation only. Concerns about asthma and pressure on the heart are unfounded.
However cosmesis is important to the full development of a child. I know I am exposing my Australian sport-loving bias when I say it is important for a young man to go swimming and to play football without worrying about his appearance. If my operation allows him to fully develop socially and in sport, I feel it is worthwhile. One must of course remember that this is an operation with all its attendant risks and it is being performed purely for cosmetic reasons.
Having said that, where there is a severe deformity at a relatively young age I do suggest strongly to the parents that they should consider surgery. While there is little evidence for it I find it hard not to imagine some restriction of cardiac filling on exertion when there is severe displacement of the heart.
Operation
The operation I perform is a modification of the sub-perichondrial excision operation popularised by Ravitch. The sternum is radically mobilised and only an absorbable PDS suture is left to support it.
The operation steps are the same for an excavatum or carinatum defect with only the final osteotomies being different. Even for unilateral deformities I usually find it necessary to perform bilateral dissections in order to make the two sides equal. There are exceptions to this where leaving the normal side intact acts as a good scaffold for the reconstructed side.
Anaesthesia, position and preparation
General anaesthesia with muscle relaxation is used. Single lumen endotracheal intubation is used, there being no indication for single lung ventilation. Intravenous access and both invasive and non invasive blood pressure monitoring should be in place. Blood group and save should be obtained but cross match should not be required. Some anaesthetists favour epidural analgesia placed prior to surgery. Because of the difficulty anaesthetising to the level of the second costal cartilage, others prefer PCAS and systemic analgesia.
The patient is placed supine. A small sandbag may be placed between the scapulae.
The skin is prepared from the chin to below the umbilicus. Draping should leave the sternal notch, nipples and umbilicus exposed to allow planning of the incision and extent of the repair.
Equipment
Special instrument sets are available for chest wall reconstruction, particularly for paediatric use. As with most procedures I try to keep to standard instruments.
- Skin knife
- Coagulation diathermy (cautery)
- Peri-osteal elevator - I use a slightly blunt elevator. If the edge is too sharp it tends to cut into the cartilage rather than developing the sub-periosteal plane.
- Doyen rib raspitories (right and left handed)
- Roberts forceps (Kochers may be useful)
- Oscillating De Soutter saw
- Sutures
- Heavy absorbable peri-osteal suture -1 Vicryl on a skin cutting needle (Ethicon 9321)
- Heavy absorbable sub-sternal suture - 1 PDS on round body needle (Ethicon 9234)
- Muscle suture - 0 Vicryl round body needle (Ethicon 9231)
- Subcutaneous- 2/0 Vicryl (Ethicon 9136)
- Sub-cuticular 3/0 undyed Vicryl (Ethicon 9717)
Incision
The incision is a transverse sub-mammary incision. It is useful to mark with ink the mid line, the upper and lower limits of the defect and the incision itself half way between these limits. As ink is frequently smudged during the operation I scratch two or three lines across the incision for later alignment. The defect is rarely fully symmetrical so the incision should be carefully marked with the eventual alignment in mind.
A corner of the pectoralis is raised being careful to cauterise each perforating branch of the IMA before it bleeds. (they can be a nuisance to stop if you miss one!) The flaps are continued superiorly to at least the level of the second rib and laterally to the costo-chondral junctions.
The incision need not extend as far as the nipples in boys. In girls it is important not to cut cross developing breast tissue. In girls I perform a more formal sub-mammary incision below the developing breasts.
The outer dermis is cut with the skin knife. Thereafter the cautery is used on a coagulation setting to complete the dermal incision, and on down through the subcutaneous tissue to the muscle fascia.
Subcutaneous flaps are fashioned to allow full movement of the later muscle flaps. Stay outside the muscle fascia to avoid bleeding.They do not need to be quite as extensive as the muscle flaps. Keep in mind that you do not want to de-vascularise the skin completely. Avoid button holing the skin. Placement of retractors superiorly and inferiorly in the corners of the incision will allow the skin to be undermined laterally to allow full rectus incisions.
Muscle flaps
Bilateral pectoral flaps will be raised as well as raising the rectus abdominis muscles as an inferiorly based flap. The incision in the muscles makes a three pointed Mercedes Benz star. A mid line incision starting at the sternal notch divides the pectoral muscles down to the top of the xiphisternum where the muscle is little more than fascia and periosteum. Two cuts are brought out infero-laterally, rather artificially dividing the inter-digitations of the rectus and pectoral muscles.
The rectus is lifted off the lower ribs with cautery. Care should be taken not to enter the peritoneal cavity but usually there is enough fat for this not to be a problem. For carinatum defects I usually excise the xiphisternum at this stage leaving it attached to the rectus muscles for later suturing over the sternum. In an excavatum defect it is usually too deep and retroflexed. There is frequently a lot of bleeding as one lifts the rectus flap so go slowly and carefully, first one side then the other as you retract down towards the inferior extent of the defect. As the costal margins can later be pulled up into the incision it is not necessary to lift the flap to the full extent of the defect.
[Some surgeons do not raise flaps, preferring to cut directly through pectoralis over each cartilage in line with its fibres. This does cut down bleeding from perforating vessels but denervates at least some muscle fibres. I like to keep as much muscle to provide bulk over my repair.]
Sub peri-chondrial resection
I start by making a H-shaped incision with cautery in the peri-chondrial over each cartilage to be excised. This is easy enough along the straight upper cartilages. The lower ones which are oblique and rotated will make it difficult to perform perfect incisions but dont worry. The important matter, particularly in children is not to go out as wide as the germinal centres at the ends of the ribs. Some surgeons use a knife to make these incisions but I find that makes for a lot of bleeding. The diathermy does tend to weld the peri-chondrium to the cartilage but I find this the lesser of two evils.
Now in turn each cartilage from the second to the costal margin is stripped of its peri-chondrium. The peri-chondrium is lifted with a combination of the force of an orthopaedic surgeon and the dexterity of a plastic surgeon, all the time knowing the heart is just behind if your hand slips. It is important to stay in the correct layer and not to drift out into the inter-costal space where you will cause bleeding. Once the peri-osteal elevator has lifted the peri-chondrium off the front of the cartilage the Doyen raspitory develops the posterior layer. I usually lever the cartilage forward with the peri-osteal elevator to guide the rongeur safely between the cartilage and peri-chondrium. Once around in the right layer it is quite straightforward to strip medially and laterally.
Using the rongeur beneath the rib to protect the pleura and vessels, the cartilage is cut at each end. Some surgeons only cut a small section from the centre of each cartilage to free the sternum but I find it better to take most of the cartilage leaving the medial and lateral ends intact. In adults it is permissible and safe to dislocate the chondro-sternal junction.
Again the lower cartilages are difficult as they are triangular in cross section and frequently have bridges between them. A little imagination is needed to obtain a successful sub-periosteal strip. Make sure the extent of the repair is symmetrical. The points of the costal margins may seem prominent once the other cartilages are excised. It may be necessary to pull them well into the wound and cut them at the point they curve back laterally.
Sternal release
At this stage the sternum is still held in place by the inter-costal muscles and diaphragmatic adhesions. If these are not divided, no metal bar made by man will withstand the constant rhythmic bending force of the chest wall muscles.
Divide the soft tissue from the tip of the xiphisternum to allow a finger to be placed under it. Develop the sub-sternal plane by sweeping the pleura laterally on each side. You will probably enter the pleura - dont worry.The terminal branches of the IMAs will be divided at this stage if they have not previously been so.
Each successive neuro-vascular (NV) bundle is divided close to the sternum. You can feel the sternum elevate with each NV cut.The NV bundles usually need to be divided as far up as the second cartilage which is the usual limit of the sub-periosteal resections. It should be possible to hold the sternum up with one finger lightly applied to the tip. Care must be taken with branches of the IMA. Usually at least one IMA is sacrificed. I attempt to keep at least one to ensure viability of the sternum.
Osteotomy
In the routine excavatum repair the aim is to excise a transverse, anteriorly based wedge of bone from the sternum leaving the posterior periosteum intact. I place the osteotomy between the second and third cartilages to leave the growth centres of the manubrium intact. A generous wedge is then cut using the oscillating saw. The posterior table of the sternum is fractured by bending it backwards increasing the deformity. The wedge can then be removed with forceps.
The deformity is then overcorrected and the heavy Vicryl on a skin cutting needle (Ethicon 9321) used to hold the edges of the osteotomy in place. I use two horizontal mattress sutures, officially holding periosteum but usually through the outer table of the sternum.
Once tied the sternum should protrude from the incision by itself with absolutely no tension on it. This removes the need for a heavy metal bar to hold it out.
In a carinatum defect a transverse cut is made across the sternum and the posterior table fractured. Wedges of cartilage are then placed in the cut to wedge it down to a corrected position. These are held in place with the heavy Vicryl using horizontal mattress sutures placed through periosteum and cartilage wedge. I usually suture the xiphisternum with attached rectus abdominis muscle to the anterior surface of the carinatum repair to hold down the tip of the sternum.
Mixed deformities will require combinations of osteotomies including a vertical cut wedged to counter the rotation of the sternum.
Fixation
There is probably no need for fixation if the mobilisation has been performed properly and there is certainly no need for a metal bar. Virtually all the complications of this operation are produced by the metal support bars. They will eventually fracture, bend or migrate and I am personally aware of the tragic consequences when a bar migrates into the right ventricle. Infection and skin penetration are common.
Hence I do not use a metal bar. I do support the sternum with two heavy PDS absorbable sutures to prevent excessive in drawing with breathing and to provide a modicum of protection to the heart. My colleague uses a slightly stronger PDS ribbon suture for the same purpose.
Two, or in larger children three, mattress sutures are placed deep to the sternum, one at the level of the fourth and another at the sixth costal cartilage, from the tip of one cartilage across to the other. In an excavatum defect I bring the sutures out on the anterior surface of the ribs to gain as much elevation as possible. In a carinatum the reverse holds, with the sutures on the underside of the ribs.
Drains
Chest drains
It is unusual to perform a radical repair without entering a pleural cavity. Theoretically one can get away without a chest drain as long as there is no air leak and the lung is well inflated at the end of the procedure. However, there is usually some blood loss into the pleura and I will place a basal drain into any pleural cavity I open. If I make only a small hole I tend to enlarge it to make sure the lung is fully inflated.
Suction drains
A 1/4 inch Redivac-style suction drain (Medinorm) is placed deep to the re-approximated muscle flaps and a second drain is placed sub-cutaneously.
Closure
After placing the chest drains and the first of the Redivacs, a stay suture is placed connecting the rectus abdominis flap with the two pectoral flaps. Each muscle corner is mattressed to prevent cutting through.
The pectoral muscles are then apposed with a running Vicryl, tying to the stay suture before completing the pectoral/rectus limbs of the Mercedes insignia. Especially with the latter two limbs I try to pick up the deep tissues with alternate sutures to reduce the potential dead space.
The superficial drain is placed and the subcutaneous tissues closed with a running Vicryl. As the defect is rarely symmetrical the incision tends to pull one way or the other. I place an initial stay suture to help line up the cutaneous tissues with the aid of the previously placed skin markers. Again, to reduce dead space, I pick up the muscle fascia with alternate sutures.
The skin is closed with an undyed 3/0 Vicryl sub-cuticular suture with all knots buried.
Postoperative care
Routine postoperative analgesia, chest physiotherapy and drain care are employed. Patients are encouraged to mobilise the day after surgery. Chest drains can come out after 24 hours provided the patient can cough out any collected blood. The superficial Redivac drain can usually be removed after 24 hours but the deeper sub-muscular drain may need to stay 4-5 days till drainage settles.
Patients are usually discharged at 4-5 days. They are discouraged from contact sports for 6-12 months as the sternum does not have its normal supports. While school can be resumed after 2-3 weeks it is sometimes wise to keep boisterous boys away for longer to avoid aggressive play and the danger of a knock on the unstable anterior chest wall.
Other procedures
Weights/suspension - historically the excavatum defect was treated by attachment of the sternum via a surgically implanted screw, to a system of weights suspended from a gantry. The weights are gradually increased over a period of weeks till the deformity corrects. The procedure is no longer used.
Sternal Turnover - the sternum and its attached cartilages can be excised en bloc. After complete excision it is turned over and wired in place. I would have reservations about the viability of the rotated sternum and its ability to grow satisfactorily in children. It is an unnecessarily complex procedure.
Peri-chondrial sling - a modification of the Ravitch procedure involves suturing the peri-chondrial sheaths behind the sternum to maintain its elevation. This practice is to be avoided as it can lad to bony constriction of the chest cavity which is not amenable to any surgical correction- a disastrous result.
Marlex sling - like our own procedure this is a modification of the Ravitch procedure but uses a sling of non-absorbable Marlex to hold the sternum. This seems a perfectly reasonable procedure. We choose to use a slowly absorbable PDS suture to avoid late effects ot infection, erosion and migration.
Nuss procedure - recently popularised as a minimally invasive procedure,this procedure involves the passage of a gull-wing metal bar under the sternum. It is then rotated with a robust handle forcing the sternum out. The bar is then wired to the ribs. It suffers all the drawbacks of metal bar insertion - loosening, fracture, migration and infection. The risk of blind passage of a bar between the right ventricle and the sternum can be reduced by observing its passage with a thoracoscope. Hopefully this will avoid the complication of cardiac laceration which has been described. Fracture of the bar is less common due to the use of a stronger modern alloy. I must say that the results as presented I would not regard as acceptable in my practice
Polands syndrome is best treated by plastic surgery involving, breast reconstruction, latissimus transfer and prosthesis,and sometimes reduction mammoplasty of the contra-lateral breast.
For sternal agenesis, slide chondroplasty of individual cartilages accompanied by longitudinal osteotomies of the sternal bars will usually bring the two halves together. Skin cover may require omental or pectoral flaps.
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