Surgical staplers are used in minimally invasive procedures for tissue transection and resection. Understanding how these staplers work also helps explain why features such as different reloads, staple heights, powered firing and articulation are incorporated into stapling systems. How the staples form depends on many factors, including the interaction between the tissue, the selected reload and the stapling system.
How Surgical Stapling Works
Before firing, the stapler jaws are positioned around the target tissue and closed. This applies compression to the tissue between the cartridge and the anvil.
During firing, three staggered rows of staples are formed on both sides of the cut line, while the blade transects the tissue between them.
The staples are formed around the compressed tissue to create the staple line. Tissue thickness, the degree of compression, reload selection, staple height and device operation are among the factors that can influence staple formation.
Why Tissue Compression Matters
Before staples are formed, the tissue is compressed between the stapler jaws.
Compression reduces the thickness of the tissue, but different tissues vary in thickness and in how they respond when compressed. The amount of tissue held between the jaws and the way it compresses therefore need to be considered before firing.
This is one reason stapling systems provide different reloads for different tissue thickness ranges.
Tissue Thickness, Reload Selection and Staple Height
Surgical tissues can vary considerably in thickness. Stapling systems therefore offer reloads intended for different tissue ranges.
Each reload uses specified staple dimensions and staple heights. The tissue being stapled should be assessed before firing so that the selected reload is appropriate for its thickness.
Closed or formed staple height refers to the space within the staple after it has been formed around the tissue. This needs to be considered in relation to the thickness of the compressed tissue.
If the tissue is too thick for the selected reload, it may not compress within the range intended for that reload. A reload intended for thicker tissue may likewise not be appropriate for thinner tissue.
Some powered stapling systems also provide feedback when excessive tissue is present between the jaws or when the device cannot proceed with firing as intended. This can prompt reassessment of the tissue being clamped and whether the selected reload is appropriate.
Why Use Progressive Staple Heights?
Tissues vary in thickness and in how they respond to compression. Within some reloads, the three staple rows also use progressive staple heights rather than a single staple height across all three rows.
This creates graduated levels of compression across the staple line. Instead of using the same formed staple height in each row, different staple heights allow the tissue to be held at different levels of compression across the three rows.
Progressive staple-height design is one approach to managing the interaction between the staples and compressed tissue across the staple line.
The appropriate reload still needs to be selected according to the thickness and characteristics of the tissue being stapled.
Staple Formation and Staple-Line Integrity
Appropriate staple formation is an important part of creating the intended staple line.
After firing, the staples should be formed as intended and the staple line assessed. Tissue characteristics, compression, reload selection, staple height and the way the stapler is used can all influence staple formation.
Staple-line integrity therefore depends on more than any single feature of the stapler.
Powered Firing and Device Feedback
Surgical staplers may use either manual or powered mechanisms to drive the firing sequence.
In a manually fired stapler, the surgeon provides the mechanical force required to advance the firing mechanism. In a powered stapler, a motorised system drives the firing sequence.
Powered systems may also incorporate electronic controls or provide information during operation. Depending on the stapling system, this may include audible or visual feedback relating to device status or conditions that affect firing.
Some technologies can also provide information about the force encountered as the device advances along the staple line.
The iREACH IRIS Powered Stapler, for example, incorporates a Real-Time Firing Curve™ that displays location-specific firing-force information during the firing sequence.
Find out more about iREACH IRIS Powered Stapler
This information provides additional visibility into the firing process but does not replace assessment of the tissue, appropriate reload selection or inspection of the staple line after firing.
Articulation and Access in Minimally Invasive Stapling
In minimally invasive surgery, the angle from which a stapler can approach tissue is influenced by the access point, anatomy and surgical approach.
Articulation allows the stapler jaws to be angled relative to the instrument shaft, providing additional positioning options when the intended transection line is not directly aligned with the access path.
The amount of articulation available differs between stapling systems and may be particularly relevant when working in confined anatomical spaces or where the available approach angle is limited.
Its relevance depends on the anatomy, access route and requirements of the procedure.
Bringing the Factors Together
Surgical stapling involves an interaction between the tissue, the selected reload and the stapling system.
Tissue thickness and compression influence reload selection. Staple height affects how the staple is formed around the compressed tissue. Progressive staple heights provide different levels of compression across the three staple rows. Powered mechanisms determine how the firing sequence is driven, while device feedback can provide information during that process. Articulation provides additional options for positioning the stapler relative to the target tissue.
These features address different parts of the stapling process and should be understood in the context of the tissue, anatomy and procedure.
Conclusion
Surgical stapling involves more than the deployment of staples. Tissue compression, reload selection, staple height, staple formation, firing and device positioning all contribute to how a stapler interacts with tissue.
Features such as reloads for different tissue thicknesses, progressive staple heights, powered firing, device feedback and articulation are designed to address different aspects of that process.
Understanding why these features are used provides useful context for how endoscopic surgical staplers are selected and used in minimally invasive surgery.