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Dr Tim Pearce
In some instances, injecting dermal fillers on the bone makes you a safer injector and can lower the risk of causing vascular occlusion (VO).
It would be great if all aesthetic clinicians had superhuman vision and could see exactly where the vessels are under the skin before we insert a needle. Sadly, we are not Marvel characters, but this can be achieved with the use of ultrasound devices. You might be surprised at what you find, anatomy is not always the same as the books – Dr Tim Pearce was amazed when he found an artery on the bone when assessing his wife, Miranda’s temple, an area he had treated multiple times previously, thankfully without causing a VO. Find out more in his blog, does ultrasound provide the evidence to support aspirating with fillers?
In this blog, Dr Tim Pearce discusses periosteal injections and how the needle gauge, depth, angle, and sharpness can help you stay safe when injecting deeper on the bone.
Why injecting deep makes you safer even if there is an artery on the bone
The decision to inject deeper, to be safer, does depend on the anatomy, warns Dr Tim. There are five points on the face where we know arteries are habitually on the periosteum, or emerging through the periosteum, these would be the most dangerous places to inject deeply – these points are the foramen.
If you are not on or near the foramen, and your needle is on the periosteum, it is usually safer, but why? The reason is that when you are truly on the periosteum there is only a limited amount of space available for you to be within a vessel. Vessels are usually separated slightly from the periosteum, even if by only a millimetre or two, or simply by the vessel wall. Dr Tim notes that you could argue there is no vessel that is truly on the periosteum, they sit above it and the lumen (the bit we are most worried about due to occlusion) is always a small distance away from the periosteum. This is why we can use a needle, particularly a small needle to be safer, regardless of whether you have an ultrasound device or not. It will be a safer way to inject than injecting at intermediate depths.
Understanding this theory hinges on the terminology used and getting your head around the resolution of the anatomy. For example, when a sonographer notes that there is an artery on the bone, what they mean is that there is a blood vessel sitting on the surface of the bone, but the lumen of the vessel is not embedded at the same level as the periosteum. If that were the case, any injection on the periosteum would occlude the vessel. However, the lumen of the vessel is always elevated by the vessel wall, and usually by a small amount of fat or other tissue underneath it, creating a little bit of distance between the location of the vessel lumen and the touching point of the needle tip on the bone. This is the crucial factor and is why a resolution of thinking is important when evaluating anatomy. Therefore, we have space to put a needle onto the periosteum because it leaves minimal space for the bevel and lumen of that needle to be beyond the vessel lumen, making us safer.
The probability of being in a vessel is much lower when you are deep and there are many things you can do to increase that safety.
Why the angle of injection is critical with periosteal injections
To highlight this in a practical demonstration, Dr Tim conducted an experiment – you can see this in the video below.
He used a mirror and a 21-gauge needle, which is much bigger than we would normally use to inject aesthetic dermal filler products but helps greatly for the purposes of demonstration. Holding the needle vertically, perpendicular to the mirror, as if the tip were on the bone, he highlights how far the lumen of the needle is off the periosteum due to the length of the bevel. This means that there is plenty of room in this experiment, as would be the case in multiple parts of the face, to have the needle tip on the periosteum but the lumen of the needle within the lumen of a vessel that was not on the periosteum. That is an immediate danger for VO.
By changing the angle of injection, you can decrease this risk. Once the needle is at a 45-degree angle, with the bevel facing down, you can note that you have more than halved the amount of potential risk from injecting. There is the option to choose an even steeper angle, approximately 30 degrees, where there is almost no space left that would risk being in the vessel lumen. This illustrates how altering the angle of injection when you are using a periosteal injection changes the area of risk to decrease the chance of vascular occlusion.
Why the size of the needle is important for periosteal injections
Similarly, another consideration when injecting is the impact of different needle sizes. Dr Tim again demonstrates this in the video where he highlights the differences between a perpendicular-placed 22-gauge needle next to a 32-gauge needle. The larger needle, with its larger bevel and lumen, presents an increased potential risk for vascular insertion compared to the smaller needle which has a lumen that is much closer to the periosteum and therefore safer. Again, an acute angle of the needle further increases the safety of the smaller gauge needle.
Check out Dr Tim’s full demonstration in the video below, including some in-practice injecting of filler product going through pseudo vessels and down to the periosteum using both needle gauges.
Why blunt needles can be dangerous with periosteal injections
When carrying out periosteal injections, the needle can become blunt simply from regular contact with the bone. It is vital that you regularly change needles to avoid danger, cautions Dr Tim.
With a blunted needle, it takes much more force to penetrate a vessel and is more likely to compress it. This is dangerous because the needle may pop through the first wall of the vessel, eventually, but it is unlikely to go through the second wall to exit the vessel; therefore, delivery of the product as you inject will be within the lumen of the vessel, causing a VO. Although there is less chance of penetrating into the vessel in the first place, with a blunted needle, it presents a fall impression which can misinform the injector. When performing periosteal injections, you are using the periosteum as your depth guide. With a blunt needle, your depth guide is impaired because when you reach the end of your ability to penetrate, you might think you are on the periosteum, but you are not, thus there is an increased danger in delivering the product. This would not occur with a sharp needle that slips easily into and out of a vessel and directly onto the periosteum.
Get more great insight from Dr Tim in his other blogs on injection depth:
- Injection Techniques,
- The best needle injection depth for dermal fillers
- Needle Depth: how can you tell where it is when injecting filler
- How to avoid 5 parallel arteries when injecting facial filler
- Do not inject filler deeply in these 6 danger areas of the face
- Download Dr Tim’s guide to the 13 extra risky injection areas which includes a facial vessel map.
He is always keen to hear about the experiences of his followers. So, if you have any tips for others or questions for him you can find Dr Tim Pearce on Instagram.
Aesthetics Mastery Show
How to stay safe with deep injecting
Dr Tim says:
“Did you know that injecting on the bone in some instances makes you safer and lowers the risk of vascular occlusion. This may sound confusing, so in this video I talk you through the areas of anatomy this applies and show you how it works in an experiment that will make this 10X easier to understand so that you can stay safe when injecting deeper.”
Watch the full Aesthetics Mastery Show here.
See comments and feedback on this video on our YouTube channel – feel free to leave a reply and join in the debate.
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Complications eLearning Course
Dermal Fillers
If you want to increase your confidence by learning how to handle complications, Dr Tim Pearce offers a comprehensive course Dermal Filler Complications Mastery. This includes CPD and certificates on completion.
In addition, browse our FREE downloadable resources on complications.
Dr Tim Pearce eLearning
Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.
Our exclusive video-led courses are designed to build confidence, knowledge and technique at every stage, working from foundation level to advanced treatments and management of complications.
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