Preventing recurrent Crohn’s Disease after surgery: the Kono-S anastomosis

In gastrointestinal surgery, anastomosis plays a crucial role in restoring bowel continuity after resection. However, postoperative complications such as anastomotic leaks, strictures, and disease recurrence, especially in conditions like Crohn’s disease, remain significant challenges. Crohn's disease presents a unique set of difficulties, as disease recurrence often occurs at the anastomotic site, underscoring the need for improvements in surgical techniques to mitigate this issue.1

The failure of biological therapies to control post-surgical recurrent Crohn’s disease has drawn attention to surgical technique as a potential key factor in improving long-term outcomes, particularly the configuration of the anastomosis itself. The Kono-S anastomosis, named after its creator Dr Toru Kono, was specifically developed to reduce recurrent Crohn’s disease and enhance the success of bowel resection.2

This article explores the development, technique, and clinical evidence for outcomes of the Kono-S anastomosis, and how it may shape the future management of Crohn’s disease.

Anastomosis refers to the surgical connection of two bowel segments following a resection, a procedure often necessary in cases of colorectal cancer, diverticulitis, or inflammatory bowel disease (IBD). In Crohn’s disease, where patients frequently undergo multiple bowel resections throughout their lives, the success of anastomosis is particularly critical. Traditional techniques, such as end-to-end, side-to-side, and end-to-side anastomoses, have been widely used for decades. However, these configurations can still result in complications, including strictures and increased rates of disease recurrence at the anastomotic site.

The Kono-S technique represents a departure from conventional approaches. Unlike other anastomoses, which primarily aim to restore bowel continuity, the Kono-S method is uniquely designed to reduce long-term Crohn's disease recurrence.

The Kono-S anastomosis is versatile, being applicable to both small and large bowel resections, and it can be performed either laparoscopically or through open surgery. This technique is even feasible in emergency cases, such as obstructive lesions with dilation of the proximal bowel, because differences in bowel calibre do not impede successful anastomosis. Additionally, no specialized equipment is required, making it accessible to a wide range of surgical settings.

To begin, the affected bowel segment is mobilized, and the mesentery is divided using a tissue-sealing device close to the intestinal wall. This preserves both vascularization and innervation at the resection margins (Fig. 1). The bowel is then divided transversely using a linear stapler placed perpendicular to the intestinal lumen and mesentery. In contrast to conventional procedures, where the stapler is positioned parallel to the mesentery, the Kono-S method positions the stapler at a 90-degree angle, ensuring that the mesentery is centered between the staple lines (Fig. 2).

The corners of the staple lines are reinforced to provide structural integrity, and the two bowel ends are approximated using 5 to 7 interrupted sutures with 3-0 Vicryl (Polyglactin). These sutures form the distinctive supporting column, a hallmark feature of the Kono-S technique that provides the anastomosis with additional stability (Fig. 3). If there is a significant size discrepancy between the two bowel segments, the sutures are spaced to distribute evenly any excess tissue, ensuring a stable and aligned anastomosis.

To create the anastomosis, a longitudinal incision approximately 7-8 cm in length is made on the antimesenteric side of each bowel stump. This incision, performed with monopolar energy, is placed no more than 1 cm and no less than 0.5 cm away from the supporting column (Fig. 4). The opening is then closed transversely in one or two layers. In our Institution we adopt a two layer technique: the outer posterior wall (mesenteric side) is constructed first using seromuscular interrupted 3-0 Vicryl sutures (Fig. 5), followed by a running 3-0 PDS (Polydioxanone) suture for the inner layer, which spans from the posterior to the anterior wall (Fig. 6). Finally, the anterior wall (antimesenteric side) is reinforced with a second layer of interrupted sutures using 3-0 Vicryl (Fig. 7). This technique results in a robust and wide anastomosis (Fig. 8), with the supporting column behind the posterior wall providing stability and preventing both mechanical distortion and narrowing of the lumen.

This anastomotic configuration also avoids the mesenteric side of the bowel wall being part of the anastomotic lumen itself. This might contribute to preventing recurrence, as Crohn’s disease always appears or recurs at the mesenteric side of the bowel wall.

Since its inception, the Kono-S anastomosis has demonstrated impressive clinical outcomes. Early data revealed a significant reduction in the severity of endoscopic recurrence compared to the conventional side-to-side anastomosis. In a retrospective cohort study, a zero rate of surgical recurrence was observed over a five-year interval. These groundbreaking results suggested that the unique structure of the Kono-S anastomosis could effectively reduce the risk of disease recurrence.2

Dr Kono attributed the success of this technique to several key factors. First, the large anastomotic lumen prevents faecal stasis and dysbiosis, both of which are known contributors to Crohn's disease recurrence. Second, the supporting column stabilizes the orientation of the anastomosis, while simultaneously protecting the lumen from the mesenteric side, where recurrence tends to originate. Even if disease activity re-emerges on the mesenteric side, the supporting column prevents lumen distortion and stenosis. Lastly, the technique's focus on preserving blood flow and nerve supply may promote better healing and bowel motility, further reducing complications.3

A larger multicenter study conducted in Japan and the U.S. later reported a 10-year surgical recurrence-free survival rate of 98.6%, confirming the Kono-S method as a promising innovation in the management of Crohn’s disease.4

While several subsequent studies have been done, with many confirming the Kono-S technique's superiority in reducing recurrence and improving postoperative outcomes and quality of life5-8, others have reported mixed results9,10, highlighting the need for further research and long-term trials.

While the Kono-S anastomosis offers several advantages, it also presents certain challenges. One major consideration is the learning curve associated with mastering the technique. Surgeons who are unfamiliar with the Kono-S method may require training to grasp its technical aspects, such as the creation of the supporting column and the perpendicular staple alignment.

Another challenge is the increased operative time compared to traditional anastomotic techniques. The Kono-S procedure, with its multiple layers of suturing and careful construction of the supporting column, can be more time-consuming, which may affect operating room schedules and costs. However, these short-term disadvantages could be outweighed by the long-term benefits of reduced recurrence and fewer complications.

The heterogeneity and complexity of Crohn's disease patients presents a significant challenge in both conducting and interpreting clinical studies on the Kono-S technique. Patients with Crohn's disease exhibit a wide range of disease severity, anatomical involvement, and response to treatment, which makes it difficult to design standardized trials. The subjectivity in assessing endoscopic recurrence, the adequacy of currently used scoring systems in assessing recurrence itself, and the presence of ischaemic ulcers at the anastomotic site leading to misdiagnosis, are all further factors potentially contributing to inconsistent results across studies. As a result, it remains challenging to draw definitive conclusions about the superiority of the Kono-S method in all patient populations, underscoring the need for further research and more personalized approaches to surgical management.

The Kono-S anastomosis represents a significant step forward in bowel surgery, particularly for Crohn’s disease. As one of the few surgical innovations aimed specifically at reducing disease recurrence through technical refinements, it stands out in the field. By trying to minimize post-operative complications and recurrence, the Kono-S technique offers patients a greater chance of long-term disease control and improved quality of life. Current data allow the conclusion that this anastomosis can be considered at least as a safe alternative to traditional techniques. Additional randomized long-term data will clarify whether the Kono-S anastomosis can become an integral part of surgical protocols for Crohn’s disease.