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Archive for the ‘cranioplasty’ Category

3D PEKK Implants For Complex Craniofacial Reconstructions

Sunday, August 31st, 2014

 

The concept of 3D printing of human replacement parts has been all over the medical and scientific news over the past few years. While each news release seems like it is revolutionary and new, most are the natural evolution of the refinement of 3D CT scanning and the ability to manufacture custom replacement parts from these images from various synthetic materials. This is of specific relevance to the skull and face where their complex anatomy make shaping natural tissues to fit difficult and often lacking inadequate donor volume to do so.

I have performed custom skull and facial reconstructions made of either HTR polymer or titanium for over twenty years…and custom silicone skull and facial implants for aesthetic enhancements over the past three years. As good as these synthetic reconstructions have been, there is always room for improvements and further technical advancements.

OsteoFab PEKK Skull Implants Dr Barry Eppley IndianapolisOne of these has been in the evolution of improved materials for custom implant fabrication with the use of the polymeric material PEEK. (polyetheretherketone)  This is a colorless organic thermoplastic polymer from the polyaryletherketone (PAEK) family. This material has excellent mechanical properties with a Young’s modulus of 3.6 GPa and a tensile strength of around 90 to 100 MPa. It is resistant to breakdown (melting) up to temperatures as high as over 340 degrees C (650 degrees F) In addition to resistance to thermal degradation, it is also highly resistant to breakdown by a wet environment or organic enzymes.

OsteoFab PEKK Facial Implants Dr Barry Eppley IndianapolisCustom implants made from PEKK were first FDA-approved in 2013 for cranial reconstructions and just recently approved in 2014 for facial reconstructive parts. (OsteoFab, Oxford Performance Materials) Through their processes it is possible to print patient-specific implants from either 3D CT or MRI scans. The implants are 3D printed and combined with laser sintering manufacturing technology and proprietary OXPEKK powder formulation to print skull and facial implants. These implants are biocompatible, mechanically similar to bone, radiolucent, and osteoconductive.

PEKK craniofacial implants offer several advantages over the traditional use of metal materials such as titanium or stainless steel. They have reduced weight, do not ever corrode, can be tailored to meet complex shapes with great precision and differing biomechanical loading properties. They also have a density and stiffness similar to bone and are radiolucent. (do not cause scan scatter) Some evidence also indicates that it has osteoconductive properties.

PEKK craniofacial implants is just one example in a long line of 3D printed biomedical advances. This technology and material allows complex craniofacial cases to be treated in a more precise manner that is ultimately more cost effective. While the actual implant(s) is not inexpensive, the savings in operative time and expense, need for donor site harvest and the high likelihood of subsequent revisional surgeries justifies the up front fabrication costs.

Dr. Barry Eppley

Indianapolis, Indiana

Case Study: Skull Dimple Correction by Augmentation Cranioplasty

Monday, March 17th, 2014

 

Background: While the shape of the skull is typically smooth, it is not rare that one may have various small contour deformities. These could be raised or indented areas depending upon their location on the skull. Many of these skull shape issues are related to their initial formation through the cranial sutures and their fusion posts known as fontanelles.

Skull Fontanelles Dr Barry Eppley IndianapolisAt birth a baby has six distinct fontanelles. The larger anterior and the somewhat smaller posterior fontanelles in the midline are the most noticed due to their size. These well known soft spots are where the skull bones have not yet fused. They exist to allow the skull plates to move, permitting easier passage through the birth canal as the head is able to change shape. After birth, they allow the baby’s brain to grow since the skull is not a fused box of bone yet. The anterior fontanelle may remain open until about 18 months of age while the posterior fontanelle usually closes by 3 to 4 months of age.

But sometimes when the fontanelles fuse, they may not fill in completely with bone of normal thickness. There may no longer be an open area between the bone edges but a complete outer and inner cortex with a well formed diploic space may not fully form. This creates an indentation in the skull or a skull dimple which appears as a circular midline depression which feels like a small crater.

Skull Dimples Indianapolis Dr Barry EppleyCase Study: This 27 year-old male was bothered by a depressed area, about the size of his thumb, on the back of his head. The overlying skin was contracted inward and the whirl pattern of his hair was directly over it. The indentation was firm with no dural palpations and was located over the area of the original posterior fontanelle.

Skull Dimple before and intraop Dr Barry Eppley IndianapolisSkull Dimpleplasty Dr Barry Eppley IndianapolisUnder combined sedation and local anesthesia, a small curved incision was made behind the skull dimple. The firmly adherent soft tissues were elevated out of the bony indentation as well as around the rim of the bony defect. The defect was then filled to the level of the surrounding skull bone with an hydroxyapatite bone cement. The scalp was closed with small resorbable sutures. A compressive dressing was then applied.

There is always some small amount of scalp swelling afterwards and, occasionally, some fluid will accumulate over the augmented area. This always resolves in a few weeks as the fluid is absorbed and the final skull contour appreciated.

Skull dimple correction is the smallest form of an onlay cranioplasty. It is simple, effective and has no real recovery associated with it. Any form of bone cement will work to fill the defect. Whether it is an open or a more injectable approach, the technique chosen is the one that can create the smoothest skull contour.

Case Highlights:

1) It is not rare for the skull to have indentations or dimples, most commonly occurring at the location of a previous fontanelle.

2) Skull dimple augmentation or skull dimpleplasty is a limited skull procedure that fills in the bone defect by application of a bone cement material.

3) Skull dimple augmentation can be done through either a small open incisional approach or an even smaller incisional injection technique.

Dr. Barry Eppley

Indianapolis, Indiana

Minimal Incision Forehead Augmentation Cranioplasty

Monday, October 7th, 2013

 

Forehead augmentation is done for a variety of aesthetic reasons including increasing the convexity and projection of the forehead. A forehead that slopes back too severely or lacks brow bone projection can be built up by an onlay or augmentative cranioplasty. This is always done with an alloplastic material rather than a bone graft due to its simplicity and long-term predictability of volume and shape.

Amongst synthetic cranioplasty materials to use for forehead augmentation are the bone cements which include PMMA (methyl methacrylate) or HA. (hydroxyapatite) Each has their own advantages and disadvantages but the one difference that usually determines which one is used is cost. PMMA offers high volumes of material at a very affordable cost. HA is the more ‘natural’ cranioplasty material but its high cost usually precludes patients choosing it.

In the September 2013 issue of the Journal of Craniofacial Surgery an article was published entitled ‘Using Methyl Methacrylate for Forehead Augmentation for Aesthetic Purposes’. In this paper, the experience using an outpatient procedure for PMMA for aesthetic forehead contouring was reviewed over a 6 year period. In 210 patients, a limited incision scalp incision was made and PMMA material was placed and molded through the skin.  The amount of PMMA was only 10 to 40 grams with a mean amount of 25 grams. In following the patient an average time of nearly four years, most patients were satisfied with the results. The authors conclude that aesthetic forehead augmentation using methyl methacrylate is an effective surgical procedure with minimal side effects and a high degree of patient satisfaction.

While the use of PMMA for forehead augmentation is not new, this study is unique because of the limited incisional approach and the small volume of material used. This is really forehead augmentation for a small amount of increased forehead fullness or convexity. PMMA is the only cranioplasty material that can be used in this approach as it can be pushed through a small incision as a congealed putty mass and then shaped from the outside by hand. This is very similar to the approach I use for a minimal incision occipital cranioplasty.

What this study also shows is the safety of PMMA as an onlay cranioplasty material. While it is more of an ‘unnatural’ material than HA, its lack of bone bonding or bone ingrowth does not detract from its long-term successful and uncomplicated use.

Dr. Barry Eppley

Indianapolis, Indiana

PMMA as an Aesthetic Cranioplasty Material

Sunday, June 9th, 2013

 

The use of skull reshaping with cranioplasty techniques that use synthetic materials dates back for over five decades. While the use of bone grafts is never an option in aesthetic skull procedures, it often is not an option in skull reconstruction either due to the size of the skull defect. This makes the use of alloplastic materials, often called bone substitutes or bone cements, as inevitable for many skull restoration procedures.

One of the historic and still most commonly used alloplastic bone substitutes in the skull is poly methylmethacrylate. (PMMA) Even though it is a polymer-based material and will never permit bone ingrowth or bone replacement, its low cost for its large volumes have always made it popular. Its widespread spread in joint replacements in orthopedic surgery as a true bone cement also speaks to its excellent biocompatibility.

Skull reshaping using PMMA has long shown it to be a well tolerated implanted material.   A recent published paper in the June 2013 issue of Aesthetic Plastic Surgery entitled ‘Aesthetic Refinement of Secondary Cranioplasty Using Methyl Methacrylate Bone Cements’ is interesting as it provides a more recent patient experience. Over a three year period the authors report on 20 patients who had PMMA implanted in their skull. Their use was reconstructive in nature for trauma and craniotomy patients and was used as a total inlay in the majority of the patients. (85%) The size of the cranioplasties was from 30 to 144 cm2 in size and involved implanted material volumes of 20 to 70 grams.

After an average two year followup period, no patients showed any evidence of implant infection, exposure, or extrusion. In addition, the PMMA reconstructions were structurally stable over this time period all the patients. The key to such successful outcomes in their observation were adequate and healthy overlying scalp tissues.

What does this mean to the aesthetic skull reshaping patients who has or is considering having PMMA implanted? This study is a small patient series that does not have significant long-term follow-up and used the material in an inlay rather than an onlay fashion. On the surface it would seem that this patient series has little correlation to aesthetic skull augmentations. But it does in one important way other than using PMMA…the scalp. All patients had overlying scalps that were healthy, not irradiated or missing tissue. Thus when re-expanded outward at the time of the reconstruction they developed no wound breakdowns or exposure.

PMMA is an effective and safe cranioplasty material. I have implanted far more PMMA in aesthetic patients than is in this paper for reconstructive purposes. I have been impressed with how well PMMA performs even though it is not remotely similar to its distant cousin, the hydroxyapatite bone cements. It does particularly well in the aesthetic skull augmentation patient undoubtably because the scalps are healthy and have never had surgery. Successful skull augmentation outcomes are predicated on normal scalp tissues because they will be stretched as the skull is built up underneath it.

Dr. Barry Eppley

Indianapolis, Indiana

The Small Incision Occipital Cranioplasty For A Flat Back of the Head

Tuesday, February 26th, 2013

 

Of all the non-craniosynostotic developmental skull deformities that exist, by far the most common is occipital plagiocephaly. This refers to a flattening on one side of the back of the head. While the deformity may be greatest on the flattest part of the occiput, its effects go beyond the flat skull area. Usually there is some compensatory bulging on the opposite normal side of the occiput as well as on the temporal side of the flattened side anterior to it. The ear positions can also be seen to be asymmetric with the ear on the flattened side more anterior than the opposite ear and may have some slight protrusion to it as well.

While a flat back of the head in an adult poses only an aesthetic deformity, to some so afflicted it can be more than just a casual asymmetric concern. While an occipital plagiocephaly in a balding male or one who shaves his head appears obvious and their concern is visible, I have seen an equal number of women with full heads of hair that are considerably bothered by it as well and adjust their hairstyles to accomodate for the aesthetic skull deformity.

The correction of an occipital flattening is done by building up the back of the head with a cranioplasty material. In and of itself, it is a fairly straightforward procedure to accomplish skull symmetry as long as one has complete visual access. Using a traditional and full ear to ear incision with peelback of the scalp does allow this exposure but many patients do not desire a full transverse scalp scar. This would be particularly true in almost all men due to their hair density and scar exposure concerns. It is always paramount to avoid trading off one aesthetic scalp/skull problem for another.

Adapting an occipital cranioplasty procedure through a smaller incision has been necessitated over the years because of scar concerns. It is possible to do the procedure but it necessitates several technical adjustments or modifications to that of a full open cranioplasty. It does not require special instrumentation but an intimate working knowledge of the handling properties of the various cranioplasty materials.

First and most importantly only one cranioplasty material has the working properties to be inserted through a small incision and molded into shape externally by scalp manipulation. PMMA or polymethylmethacrylate, acrylic bone cement, can be mixed into a putty which at a certain point in its set is not too loose but has not started to fully polymerize either. It is this window in the setting of the material that can permit it to be inserted through a smaller incision and still have adequate flow properties to be molded once inside. Unfortunately, none of the HA or hydroxyapatites have these working propertiues to be of great value for this approach. I have tried every HA material available and they all come up wanting, either in too short of set times or lack of adequate flow characteristics.

While a cranioplasty material can not really migrate around or away from its pocket on the bone, like other implants in soft tissues, some anchorage to the bone is always a good idea…even if it is just for psychological reassurance The best way to do that is to place small 1.5mm self-tapping titanium screws into the bone leaving them slightly above the bone surface. This will allow the PMMA to flow around them and lock onto them while it is curing. Since PMMA never really bonds to the skull bone, although there is some justification to calling it a bone cement since it does have some stick to it, this small screw fixation certainly prevents any micromovement. As long as too many screws are not placed or the screws are not too big, it is really quite easy to pop the implant off the bone later should that ever be necessary. In essence, their use does not make secondary removal unduly difficult.

Once the PMMA material is inserted, the scalp incision needs to temporarily stapled together. This then allows one to shape the material and feather its edges by external scalp manipulation. There usually is a few minute window to do the molding. While in years past the final set of PMMA was associated with very high heat release, this is no longer true. The exothermic reaction is very minimal with newer formulations so there is no risk of thermal injury to the scalp tissues. Once shaped and set, the staples are removed and partial visual assessment can then be done internally. (although this will be very limited as the material now occupies the entire pocket and the small incision makes it very hard to look over all the augmented area)

One advantage to the small incision cranioplasty is that the risk of difficulty with incisional closure is less because the molding is usually done away from it. This prevents the risk of encountering an incision that can not be closed due to the augmentation volume. When possible it is always best to have an incision in which no cranioplasty material lies underneath it. (ideal but not always possible)

The small incision occipital cranioplasty can be a very effective method of skull augmentation. Patients can have a very quick recovery and very minimal discomfort. But it is very technique dependent and requires good experience with more open methods of cranioplasty before attempting it through limited access.

Dr. Barry Eppley

Indianapolis, Indiana

Postoperative Instructions for Cranioplasty (Skull Reshaping)

Monday, January 28th, 2013

 

Skull reshaping surgery is done to create a more normal skull shape and contours. It achieves this goal through the application to the outside of the skull of either augmentation (by adding materials), reducing bone or a combination of both techniques. Most skull reshaping techniques require an open incisional approach to be done.

The following postoperative instructions for skull reshaping surgery are as follows:

1.  Skull reshaping surgery has a surprisingly minimal amount of postoperative discomfort. Pain medications are prescribed should you need them and you should take them as directed on the label, usually 2 tablets every 3 to 4 hour as needed. Many patients only use Tylenol; or Alleve after the first few days of surgery.

2.  There will be a circumferential head wrap applied at the end of the procedure. This is to be worn for the first night after surgery and can be removed the next day. Thereafter no dressings are needed. You may take it off the next day to shower.

3. In some cases of skull reshaping surgery, a drain will be used for the first day after surgery. This very small tube will be connected to a small bulb which collects any fluids. Empty the bulb as directed and there is NO need to measure the amount of fluid that comes out. In most cases of skull reshaping surgery, the bulb usually does not fill enough to be emptied more than once. The drain will be removed the day after surgery.

4. The scalp incision will be closed with either resorbable sutures, permanent sutures or small metal staples.There is no need to apply any antibiotic ointment to the incision, just leave them dry. Resorbable sutures do not need to be removed. Permanent sutures and staples will be removed 7 to 10 days after surgery. You may shower 48 hours after surgery and wash your hair.

5. You may wash your hair 48 hours after surgery. It is alright to get the sutures or staples wet. Dry and style your hair as desired. Be careful combing your hair so you do not catch the comb in the sutures or staples.

6. Strenuous physical activities and working out should wait for at least one week after surgery. While you can not harm the result by anything you do, wait until you feel better before exerting yourself.

7. You may eat and drink whatever you like right after surgery.  Focus on liquids and soft foods for the first few days after surgery.

8.   You may return to work and any non-strenuous physical activity as soon as you would like based on your comfort level.

9.   You may drive when you feel comfortable and can react normally and are off pain medication.

10. If any scalp or incisional redness, tenderness, or drainage develops after the first week of surgery, call Dr. Eppley and have your pharmacy number ready.

Consent for Plastic Surgery: Cranioplasty (Skull Reshaping)

Monday, January 28th, 2013

 

Every plastic surgery procedure has numerous issues that every patient who is undergoing a procedure should know. These explanations are always on a consent form that you should read in detail before surgery. This consent form, while many perceive as strictly a legal protection for the doctor, is actually more intended to improve the understanding of the various skull reshaping procedures. The following is what Dr. Eppley discusses with his patients for these procedures. This list includes many, but not all,of the different outcomes from surgery. It should generate both a better understanding of the procedure and should answer any remaining questions that one would have.

ALTERNATIVES

There are no alternatives to surgical skull reshaping. Some small skull defects may be treatable by a fat injections or bone cements placed through a minimal incision injection approach. High spots or skull reduction can not be reduced by a non-incisional approach.

GOALS

The goal of skull reshaping surgery is to create a more normal appearing skull contour. In some cases, this may require building up the bone, reducing raised areas or a combination of both reshaping techniques to get the optimal skull contour.

LIMITATIONS

The limitations of any cranioplasty procedure are how much of an incision can the patient tolerate (access and exposure), how much the skull can be built up based on the scalp’s ability to stretch and the thickness of the skull bone when reductions are being done.

EXPECTED OUTCOME

Expected outcomes include the following: temporary swelling of the scalp even extending down into the face, scalp skin numbness, a permanent scalp scar, the implantations of various biomaterials for augmentation/buildup including microcrew anchorage and months of healing and tissue settling until the final result is seen in all aspects. Healing of any cranioplasty procedure is a process and the minimal amount of time to judge the result is three months and may take as long as six months to see the very final result in many cases.

RISKS

Significant complications from skull reshaping surgery are very rare but could include infection. More likely but uncommon occurrences could include a wide scalp scar, potential hair loss along the incision, suture reactions along the incision edges causing local wound healing problems, edge demarcation/irregularities along any implant-bone interface, overcorrection of the skull contour, undercorrection of a skull contour, and asymmetries and irregularities of the skull contour. Any of these risks may require revisional surgery for improvement.

ADDITIONAL SURGERY     

Should additional surgery be required to revise a scalp scar, adjust a bone or implant contour or perform aesthetic adjustments of the initial skull reshaping will generate additional costs.

Case Study: Cranioplasty for the Flat Back of the Head

Monday, July 23rd, 2012

Background:  The shape of the head is largely determined by the skull that lies underneath it.  Its normal oblong shape is created by the multiples plates of skull bone formed in utero that only formally fuse together after birth. The rapidly developing and expanding brain has great influence on forming the skull shape, much like an internal tissue expander.

But if the bone is blocked from being expanded, it will result in the push of the brain being directed elsewhere. This blocking effect can be created by a suture fusion (craniosynostosis) or an external force. By far, the most common cause of skull asymmetry is external molding. The most frequent form of external molding is inadvertent pressure caused by laying on one side of the head too long as a baby. This causes a classic flattening on one side of the back of the head with compensatory overgrowth on the other side. This is known as occipital deformational plagiocephaly.  On careful examination, one can often see from above that the entire head is twisted or rotated causing a cranioscoliosis effect in more severe cases.

With today’s shorter hairstyles and shaved heads, bothersome flat spots on the back of heads are becoming more evident. Often the ear on the flat side is moved further forward than the opposite ear and even the neck muscles on the flat side are asymmetric to the other side. These posterior skull asymmetries have given rise to patient’s requesting if they can be improved by some form of plastic surgery.

Case Study: This 42 year-old man was extremely bothered by the flat spot on the left side of back of his head. He had shaved his head for years since he began balding. To hide his concern about his flat spot, he always wore a hat to camouflage it. In discussing the option of a craniplasty correction, the issue of the trade-off of a fine scar was discussed. His level of concern about the back of his head made the scar issue a palatable exchange.

Under general anesthesia, a 9 cm horizontal posterior scalp incision was made. Wide exposure was made of both the normal and flat side of the occiput. Two small 1.5mm screws were placed at two different levels of the flat side marking how high the augmentation had to be for symmetry. Then using a PMMA acrylic cranioplasty material of 30 grams impregnated with antibiotic powder, a putty was made and inserted through the incision onto the flat occiput. The material was shaped through a combined internal and external methods until the area was both augmented and smooth and all edges were feather-like. The material set in ten minutes and the incision was then closed. A circumferential head dressing was applied and no drain was used. The length of the surgery was 90 minutes.

He had only minor discomfort the first night surgery and none thereafter. His head dressing was removed the next day. He had some expected swelling but no pain. Dissolveable sutures were used so removal was not necessary. He was placed on no restrictions after surgery and he could shave his scalp around his incision site 48 hours after surgery. His degree of occipital symmetry was dramatically improved.

Correcting a flat spot on the back of head is no different than a frontal or forehead augmentation. It is an onlay cranioplasty that requires a biocompatible material and an incision to place it. Scars are made as small as possible and material options are either an acrylic PMMA or HA. (hydroxyapatite) Cost plays a role in material choice. How much skull symmetry can be achieved is largely based on the volume added. The limiting factor in how much volume can be placed is scalp tightness and getting a good incision closure, preferably not directly over the implanted material.

 Case Highlights:

1)      One of the most common skull deformities is flattening on the back of the head, also known as occipital deformational plagiocephaly.

2)      Building up the flat back of the head is done by an onlay cranioplasty procedure, using a variety of different materials.

3)      Using an open approach, an occipital cranioplasty procedure is both very effective and involves minimal recovery.

Dr. Barry Eppley

Indianapolis, Indiana

Cosmetic Skull Augmentation of the Flat Back of the Head

Tuesday, July 26th, 2011

When one thinks of cosmetic surgery, the thought rarely goes to any form of skull contouring. While the world is full of a wide variety of head shapes, there is no uniform size or measurement to determine a pleasing cranial contour. But there is a certain oblong and curvilinear shape to most of the skull. The forehead, which is really the front part of the skull, has some very specific desired shapes and contours that are very gender-specific, but the rest of the skull has less well-defined determinants of being pleasing in appearance.

Despite the comparatively obscure location of the back of the head (occiput) compared to the forehead, not everyone is entirely pleased with this portion of their skull shape. The typical concern is that the back of the head is too flat without adequate projection. Whether it be the entire occiput or limited to just the crown area (upper occiput), this is a legitimate cosmetic concern for those so affected. For anatomic clarification, the bony portion of the occiput actually stops at about the level of the middle of the ear. The rest of the back of the head is muscle and other soft tissue.

The most effective method of occipital skull contouring is augmentative, putting a material on top of the bone to build it out. This is a common form of cranioplasty that has a long history in the forehead, it is just less commonly done on the back of the head. There are multiple ways to perform an occipital augmentation cranioplasty and they differ primarily in the material used and the incisional approach to get it there. Each has their own distinct advantages and some disadvantages.

The open form of an occipital cranioplasty involves a transverse incision of about 8 or 10 inches on the upper part of the back of the head. This approach heals better than any other scalp incision in this area. The scalp is lifted off of the bone around a premarked area of the flattening. Through this approach, either an acrylic (PMMA) or calcium hydroxyapatite (HA) material can be mixed, placed and contoured to the desired shape. Both are powders and liquids that are mixed together to form a moldable putty which as about 10 minutes of working time. Because it is a putty, thus is why it needs an open approach to be placed. Acrylic has the advantage of setting up as solid as bone and just as fracture-resistant. That would offer a theoretical advantage on the back of the head since we lay on it all the time. HA, which setting up firm, is a bit more brittle and fracture-prone although I have never seen that to be a problem in the forehead. With either material, the open approach offers the best chance for a very smooth and even contour shape.

The limited incision approach uses a three to four inch incision through which the materials are ‘pushed’ through as a putty and molded from the outside as it sets. The only cranioplasty material that has the physical properties once mixed (for the first 12 minutes) to be a good moldeable putty is PMMA or acylic.The disadvantage to the limited incision approach is that there is a higher risk of contour irregularities and palpable edges. This occurs because the molding of the material as it sets is done from the outside so there is no visual way of confirming how smooth it is as it sets.

Cosmetic contouring can be done on most areas of the skull. Occipial augmentation cranioplasty can be done to build out a flat spot or entire back of the head. Regardless of the material and the incision used, it is a simple procedure for a patient to go through with very minimal recovery. Patients report having a headache for a few days but no real pain. Once can wash their hair within 48 hours. Some mild swelling can be expected and the final result can be fully appreciated within 6 weeks after the procedure. All of the cranioplasty materials used are permanent so the change in skull contour will be maintained over one’ lifetime.

Dr. Barry Eppley

Indianapolis, Indiana

Screw Fixation of Acrylic Onlay Cranioplasty

Tuesday, July 19th, 2011

One of the techniques for contouring of the skull is augmentative cranioplasty. This is where the skull or forehead is built out through the use of a variety of synthetic materials. While bone would seem to be a logical choice, it is associated with resorption when used as an onlay not to mention the need for a donor site. Synthetic materials offer contour stability, off-the-shelf ease of use and the elimination of a donor site. Even though there is a risk of infection with synthetics, their benefits far outweigh this very uncommon cranioplasty risk.

One of the most common cranioplasty materials is acrylic or PMMA. (poly methylmethacrylate) It has been used successfully for decades and offers a material strength that is similar to bone and is virtually impact-resistant. It is used in orthopedics as a bone cement for joint prostheses but on the skull it does not have ‘cement’ capabilities. This means that the material does not bond to the bone or the overlying soft tissues. Rather it forms a scar capsule around the material, particularly between the material and the underlying bone. This means that there can be small amounts of motion or instability of the cranioplasty material. In revision of pure onlay cranioplasties, it can be very easy to lift the material off of the bone. This material looseness may or may not cause any long-term problems.

Since a PMMA cranioplasty does not bond to the bone, I have always used an anchoring method for the material. The simplest method is to preplace small titanium crews into the outer table of the skull and leave them raised several millimeters. When the cranioplasty material is applied, the initial putty phase of the material wraps around and grabs the screwheads. Once cured, there is a rigid lock of the material to the bone. This prevents any chance of instability or shifting of the material on the skull’s surface.

This screw anchorage of cranioplasties can be used at any location on the skull. It is of particular value on the occipital (back of the head) region where the skull is exposed to the greatest amount of regular stress. (laying on the back of your head)

This cranioplasty fixation method is not as important with the use of other materials such as hydroxyapatite. While these materials are far weaker and minimally impact-resistant, they do have the ability to bond to bone so they have no risk of material movement or instability.

Dr. Barry Eppley

Indianapolis, Indiana


Dr. Barry EppleyDr. Barry Eppley

Dr. Barry Eppley is an extensively trained plastic and cosmetic surgeon with more than 20 years of surgical experience. He is both a licensed physician and dentist as well as double board-certified in both Plastic and Reconstructive Surgery and Oral and Maxillofacial Surgery. This training allows him to perform the most complex surgical procedures from cosmetic changes to the face and body to craniofacial surgery. Dr. Eppley has made extensive contributions to plastic surgery starting with the development of several advanced surgical techniques. He is a revered author, lecturer and educator in the field of plastic and cosmetic surgery.

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