Background: The shape of one’s skull is not often thought of as a major cosmetic issue. Much of this is because it is largely hidden by hair in most women and in many young men. But with hair loss in men and the contemporary hairstyle of total scalp shaving, the shape of one’s skull and upper forehead can take down a more dominant visible role. The overall size of the skull is actually greater in surface area than that of one’s face. And, unlike the face, it is generally desirous to be more of a smooth oval rather than have a lot of indentations and irregularities.

Reshaping of one’s skull can be done by either bone reduction or augmentation by onlay materials. By far, more significant changes can be made in the shape of an adult’s skull through addition rather than subtraction. Such cranioplasty procedures have been historically done through an open scalp (coronal) approach. By making a long transverse scalp incision, the scalp tissues can be widely elevated providing wide open exposure and an unobstructed working field. When one has a skull deformity as a sequelae of a prior neurosurgery or craniofacial procedure, the use of a pre-existing scalp incision makes the decision easy to proceed with skull contouring. In the absence of a prior scalp scar, however, the decision to undergo any form of skull reshaping is complicated by the scar’s cosmetic trade-off.

Case Study: A 25 year-old male wanted skull and forehead reshaping due to some cosmetic irregularities. He had a pair of grooves or indentations on each side of the midline of his skull that ran from the back of his head to the middle of the forehead. These depressions were visible given his receding hairline and close cropped hair. These parasagittal linear indentations were somewhat reminiscent of a ‘miniature’ or micro- form of sagittal craniosynostosis as noted by a midline ridge along the sagittal suture and restricted bone growth perpendicular to it along its length. He has trouble wearing hats as his narrow forehead allowed the hat to fall down unsupported to his brows.

These parasagittal skull grooves could be easily augmented through a traditional open cranioplasty approach. Understandably he did not want the scalp scar given the modest nature of the skull problem. An alternative approach of an injectable cranioplasty procedure was devised that could be done through very small incision but yet could add material over the entire lemgth of the skull defects. Such an approach, while not possible with the use of traditional cranioplasty materials such as acrylic and hydrozyapatite, can be done using the newly FDA-approved Kryptonite bone cement.

Prior to the procedure, an outline of the skull depressions were marked on both sides. Clay modeling material was used to fill in the defects and shaped. They were used to give an estimate of how much material would be needed to fill in the defects from front to back. The patient was taken to the operating room where a small one inch incision was made at the back end of the linear  depressions. Long curved elevators were used to raise the scalp tissue off of the bone in a subperiosteal plane within the confines of the skin marks. The pocket was the washed out with antibiotic solution. On each side, 10 grams of Kryptonite bone cement were then injected from front to back using a syringe and a long 12 French plastic catheter. The material was shaped externally by molding with fingers to get smooth edges and sn even fill of the skull depressions to the surrounding skull bone. Once set after 10 minutes, the incisions were closed with small dissolveable sutures. Total operative time was one hour and was done as an outpatient procedure

When seen the next day, he reported only a mild headache for a few hours after surgery. He took no pain medications at all. His swelling was mild as expected and he had no bruising. The effects of the skull contouring was immediately evident and pleasing. However, swelling remains and the final outcome of the procedure will take several months before its true success can be judged. What the procedure does illustrate is that it is possible to do select cranial augmentation using this method. It is fairly simple and the patient will have a quick recovery.

For more modest skull contour deformities where a long scalp incision would be cosmetically unacceptable, the injectable cranioplasty method is a viable method. It is made possible with the flow characteristics of Kryptonite bone cement that have not previously existed with prior cranioplasty materials.

Highlights:

1)      Skull irregularities and contour depressions have traditionally used an open scalp incision with its own cosmetic scar trade-off.

2)      Injectable cranioplasty uses very small incisions that can fill in a large surface area through a long flexible filler tube. It is a procedure that is technique sensitive and intimate working knowledge of how the Kryptonite material flows and sets, and the time frame on which it happens, is needed to ensure a good result.

3)      Cosmetic skull reshaping by augmentation is now possible with the minimally invasive cranioplasty (MIC) procedure. Further work is needed to define the procedure to avoid undercorrection and, most significantly, any risk of overcorrection.

Dr. Barry Eppley

 http://www.eppleyplasticsurgery.com

Indianapolis, Indiana

Pectus excavatum, also known as funnel chest, is a defect characterized by differing levels of sternal depression. The deepest area of the sternal depression is always on the lower third of the sternum near the upper abdominal area. The lower costal or rib cartilages dip backward to increase the deformity or depression and push the sternum posterior backward towards the spine.

Significant pectus deformities are treated when the patient is young, usually between 12 to 18 years of age. At this age, the plasticity of the cartilages make this age group the ideal period for repair. While extensive cartilage resection (Ravtich approach) has been the historic approach. This radical operation has been replaced by the Nuss Procedure which involves the placement of a large curved bar through incisions on the chest wall. The bar is rotated into position and kept in place for 2 to 3 years.

But not all sternal reconstructive surgery leaves a perfectly flat or well curved sternum. In addition, some patients have very small sternal depressions that were either not recognized for early treatment or were not significant enough for any form of sternal reshaping and respositioning. Such cosmetic sternal deformities have been traditionally treated with onlay implants usually composed of preformed or custom carved silicone. Gore-tex blocks and sheets have also been used as sternal inserts.

But these synthetic materials have not been without their complications including infection, seroma formation, and capsular contracture. This has resulted in either their need for removal or the outcome of a hard and unnatural feeling implant. This is largely because these synthetic materials are not intended to be bone substitutes or replacements so they never integrate and become an extension of the natural sternal bone. Better sternal onlay materials would be an asset and could provide a better option for smaller sternal depressions that don’t warrant invasive bone reshaping.

The ideal sternal onlay augmentation material would adhere to the bone surface, have bone-like firmness and fracture resistance, and be injectable. The need to be delivered into the sternal site by injection is critical as any incision across the sternum is a cosmetic deformity by itself. Of all available bone substitute materials historically used, none fulfill all of these criteria. Most are hydroxyapatite-based which are neither injectable or fracture-resistant.

The recent commercial introduction of Kryptonite bone cement has the potential to fulfill these sternal criteria. Kryptonite Bone Cement is a non-toxic, porous, adhesive bone substitute material that possesses bone-like mechanical properties. It is composed of naturally occurring fatty acids and calcium carbonate. It’s three ingredients are mixed together at the time of surgery to create an initial liquid material that converts into a firm putty within minutes. It is Kryptonite’s liquid phase after mixing that makes it injectable.

Kryptonite bone cement has been shown experimentally to be an easily injectable material for limited incision or minimal access cranioplasty. It can flow through small diameter (3mms) plastic tubing, can be easily molded through the skin by outward digital molding pressure, adheres to the bony pocket created, and does not stick to the overlying skin. Its success for a cranial surface suggests that it would work equally well on the sternum, which represents just another flat bone surface. Through a small (< 10mm) lower sternal incision, a subperiosteal pocket can be easily created and injected. The material can be molded to fill a sternal defect and harden in 15 minutes. Once set, it will feel like natural bone and will encapsulate with the underlying sternum

Kryptonite bone cement represents a viable sternal augmentation material. Its ability to be placed by injection opens up treatment possibilities for those with sternal depression deformities that would not otherwise merit more extensive surgical reconstruction. 

Dr. Barry Eppley

www.eppleyplasticsurgery.com

Indianapolis, Indiana