What is the difference between micro-cannulas and cannulas? A cannula is little more than a tube that does not terminate in a sharp point – but has a blunt tip. This is the primary difference between a cannula and a needle. A blunt- or smooth-tipped micro-cannula is further defined as one being used as an injection device, (inserted via a sharp needle created entry point), with a hole, or port in the side of the shaft.
Within aesthetic medicine, the terms ‘cannula’ and ‘micro-cannula’ are routinely used in an interchangeable fashion. Often a distinction is made between the two words based on the shape of the blunt tip. This is in fact incorrect, and no distinction is needed for the use of the nomenclature.
In other words, there is no difference if someone refers to using a cannula or a micro-cannula for subdermal injectable aesthetic treatments. Yet there is still much confusion over the appropriate terminology, the exact definition of a micro-cannula, and the differing product types available.
Differences between micro-cannulas
Core differences between micro-cannulas include:
- the shape of the blunt tip;
- the location and orientation of the side port;
- the length of the shaft;
- the flexibility of the shaft;
- the smoothness or slide of the outer shaft;
- the internal diameter size or wall thickness;
- and the extrusion pressure required to deliver product.
Shape of the tip
The shape of the blunt ended tip of a micro-cannula has a bearing on the ease of entry into the subdermal tissue layers; shapes vary from round to dome-like.
The distance of the extrusion port from the tip of the micro-cannula is also key. The closer this opening is to the tip, the more precisely product can be placed as the practitioner can both see and feel the end-point. Similarly, less product is lost or wasted by accumulation in the tip. Breakage during use is also reduced with a side port that is closer to the tip.
The length of the micro-cannula effects the range of movement available to the practitioner, as well as the size of the area treatable through an individual entry point.
Shaft flexibility is a balancing act; you want it rigid enough to achieve precise product placement, yet flexible enough to glide through the subdermal tissue. A cannula that is ‘too bendy’ is not appropriate for aesthetic injectable applications.
Many devices are described as having ‘thin walls’, where there is an increased internal diameter to the shaft. The thinner the walls, the faster the flow of product, and the reduced extrusion forces needed to inject; which is particularly useful for highly viscous fillers.
Two types of micro-cannulas
TSK Laboratory offers two distinct types of micro-cannula to the aesthetic marketplace. The traditional CSH (Closed-tip Side Hole) micro-cannula range comes with a round-shaped tip and features ultra-thin walls.
TSK’s flagship STERiGLIDE™ range of ultra-thin walled micro-cannulas introduced a domed or tapered shape to its blunt tip. This newly designed tip provides less resistance on cannula entry than a traditional round tip, which in turn reduces friction through the tissue, reduces the force need to introduce the cannula, and minimises bruising for the patient. Combined with a more rigid construction and a proprietary surface treatment to the stainless steel of the shaft, STERiGLIDE has a 50% improvement in its ability to glide through the structures.
Its side port, the orientation of which is visibly marked on the hub, is also located as near to the tip as possible for accurate product delivery and minimal product loss.
All of these design features have made STERiGLIDE a cut above traditional micro-cannulas, award-winning and considered by many as the gold standard for blunt-tipped micro-cannulas for use in aesthetic practice.