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Nuss bar

The nuss bar is the most important factor when undergoing the nuss procedure. Carefully chosen, crafted and implemented bar is what makes or breaks a nuss procedure surgery. By default, a stainless steel bar is used and inserted under the patient's sternum area, unless preoperative test indicate some kind of metal hypersensitivity. In that case, the metal bar is replaced with a titanium one.
picture of male chest with pectus bar insadeThe nuss or pectus bar is the most important factor when undergoing the nuss procedure. Carefully chosen, crafted and implemented bar is what makes or breaks a nuss procedure surgery. By default, a stainless steel bar is used and inserted under the patient’s sternum area, unless preoperative test indicate some kind of metal hypersensitivity. In that case, the metal bar is replaced with a titanium one.

How is the Nuss Bar measured ?

The measurement of the lenght and shape of the nuss bar is done preoperatively, according to the needs of each patient individually. This is usually done by the surgeon prior to the operation. The surgeon using a sterile pen marks the left and right intercostal spaces of the chest corresponding with the deepest point of the depression. This is used as a visual reminder as to where to make the cuts and where to insert the bar during the operation. This way the length of the bar is also determined. It is measured from the marked line on the left side to the marked line on the right side and 1 to 2 cm is usually subtracted from the full measurement. Than according to the type of deformity (symmetrical or asymmetrical) the pectus bar is bended at the right position. Most common instrument used for this is the Zimmer bar bender. It is worth noting that this is the most critical part of the whole process and if not done correctly, the final result will not be pleasing aesthetically as they should be. The experience of the surgeon plays a major role in this and it is not recommendable for inexperienced surgeons.

 

doctors bending zimer bar bender

Nuss bar sizes, strength and materials

The currently used metal bars are made out of steel (type AISI 316L) and their sizes range according to the anatomy of the patient’s thorax. Documentation shows they can range from 178mm up to 458 mm in lenght, 2.5mm to 3.5mm in thickness and up to 13mm in width. 

 

pectus bar in order and different sizes

 

 

 

 

 Stainless steel 316 LVM materials : iron, chromium, carbon, nickel, silicon, nitrogen, manganese, sulfur, phosphorus, molybdenum, eisen chrom, carbon silicon, stickstoff mangan, nickel phosphor

 

 

 

 

 

 

 

These pectus bars have been tested to the maximum force they can endure without deforming and according to a study made by Webber (Forces to be overcome in correction of pectus excavatum. J. Thorac. Cardiovasc. Surg. 2006) the maximum force is 250N.

 

how much force can a pectus bar sustain

(a) CAD representation of metal bar with applied force of 250 N (red arrow C) and the two “fixed support” constraints (A,B) (b) Stress distribution on the bar. The area subjected to the maximum stress is shown in the inset.

 

Possible bar complications 

  • Alergic reactions due to metal sensitivity
  • Abnormal sensation, numbness or pain due to the presence of foreigh object
  • Permanent or temporary neve damage, permanent or temporary damage to hearth or lung
  • Can cause pressure to internal mammary arteries, obstructing the natural blood flow
  • Skin around the incesions can get itchy, infectious  or numb
  • If the modeling of the bar is not adequate, it can lead to return of the deformity before or after the bar removal
  • As in any surgery, possible injury or death

 

Bar removal 

When undergoing the nuss procedure, the pectus bar stays inside the patient from two to three years. By this time it is expected the sternum and ribs to be set and fixed into correct procedure and the bar is no longer needed. The surgery for the removal of the bars is fairly less complicated than the initial surgery. It takes one hour approximately and is done through the same incisions, so no new scars will be formed on the body. The hospital stay ranges from one day to two, depending on the patient.