More than 1.5 million patients have Crohn's disease (CD) worldwide, with a recent
significant increase in Asia. The incidence of CD in Japan has increased dramatically
during the last two decades, and the nationwide population of patients with CD is
currently approaching 50,000. Despite the advances in medical therapy, ∼80% of patients
with CD will require intestinal resection for complications related to stricturing
or penetrating disease during their lifetime, with high postoperative rates of anastomotic
recurrence and stenosis necessitating repeat surgery.[1]
[2]
[3]
[4] In one study of patients treated with surgical anastomosis, endoscopic recurrence
at 6 months was observed in up to 60% of those who underwent ileocolic resection,
and 20% to 30% of patients who underwent surgery required a second surgery within
5 years.[3] Anastomosis and recurrence are intrinsically related. Postoperative recurrence typically
occurs at the anastomotic site or in the neoterminal ileum in patients with previous
ileal involvement.[5] Although several studies have shown the efficacy of anti-tumor necrosis factor (anti-TNF)
agents in preventing postoperative endoscopic recurrence rates in patients with CD,[6] a recent prospective randomized controlled study showed that the clinical recurrence
rates were not different between the infliximab group and the placebo group.[7] Therefore, the ability of anti-TNF agents to reduce clinical recurrence and surgical
recurrence has not yet been determined.[8] Moreover, no surgical strategies have been developed to prevent postoperative surgical
recurrence.[9]
[10] Therefore, efforts should be made to optimize surgical techniques and offer the
best possible operative treatment to the right patient at the right time.
In September 2003, Kono et al began using their unique surgical technique (Kono-S
anastomosis) to prevent anastomotic strictures in patients with CD at the Asahikawa
Medical University Hospital in Hokkaido, Japan.
Kono et al first reported the outcomes of this novel technique in a comparison between
69 patients who underwent Kono-S anastomosis and 73 patients who underwent conventional
anastomosis (hand-sewn end-to-end, hand-sewn side-to-side, or stapled functional end-to-end
[FEE]). Surgical recurrence was significantly less likely with this new anastomosis
technique (0 vs. 15%, p = 0.0013).[11] Since 2010, Kono-S anastomosis has been adopted in 23 leading medical centers, including
18 university hospitals in Japan.[12]
[13]
[14] In May 2010, Kono-S anastomosis was introduced at the University of Chicago and
subsequently at the University of Washington, Weill Cornell Medical Center, and University
of North Carolina. Fichera et al evaluated 44 patients who had undergone 46 Kono-S
anastomoses and reported no surgical recurrences during the study period.[15] In 2016, an international multicenter study conducted at five university hospitals
(4 in Japan and 1 in the United States) analyzed 187 patients who had undergone Kono-S
anastomosis for CD with a median follow-up of 60 months.[13] In the Japanese cohort (144 patients), surgical recurrence occurred in only two
patients, with a 5-year cumulative surgical recurrence rate of 1.7% during a median
follow-up of 65 months. In the United States group (43 patients), no surgical recurrences
occurred during the follow-up period of 32 months. This excellent result suggests
that Kono-S anastomosis appears to be safe and effective in reducing the risk of surgical
recurrence in patients with CD. Multicenter prospective randomized trials comparing
Kono-S anastomosis with conventional side-to-side anastomosis are currently underway
in the United States (NCT03256240) and Europe (NCT02631967).[10]
We outlined the standard Kono-S anastomosis procedure, adopted at the Second International
Consensus Conference on Kono-S Anastomosis held in October 2015 in Nagoya, Japan.[16] We also described the theoretical background of this procedure and the fundamental
differences between Kono-S and stapled FEE anastomosis as well as other conventional
anastomotic techniques.
Kono-S Anastomosis Procedure
The Kono-S anastomosis technique is illustrated in [Fig. 1] using the example of multiple ileal stenosis, one of the most common types of CD
lesions in Japan.[13]
Fig. 1 Multiple ileal stenoses in a patient with Crohn's disease. A 36-year-old man had
Crohn's disease complicated by multiple stenoses in the small intestine. Six strictures
spanning 40 cm were located within the distal 73 cm of the terminal ileum.
Confirmation of the Lesion
Surgical success is dependent upon a detailed preoperative evaluation of the lesions
and other parts of the intestinal tract, which are often compromised by adhesions,
multiple disease foci, and other abnormalities. Whether using the open or laparoscopic
approach, the surgeon must carefully trace and observe the patient's small bowel starting
from the ligament of Treitz ([Fig. 1]). Surgical lysis of adhesions may be necessary for mobilization of the gastrointestinal
tract. The surgeon determines the length of the small intestine as well as the extent
of the disease using a sterile tape measure or other appropriate tools ([Fig. 1]). Before making the final decision on the surgical procedure intraoperatively, the
surgeon may need to endoscopically observe the identified lesions and the future remnant
tract segments to ensure that no active lesions were missed in the preoperative assessment
([Fig. 2]).
Fig. 2 Intraoperative endoscopy. The whole bowel is carefully inspected for diseased segments
using an endoscope via an enterotomy placed at the stenotic site. Intraoperative endoscopy
is performed by a gastroenterologist when unexpected incidental surgical findings
are noted upon exploration.
Determination of Anastomosis Location and Resection Margin
Attention must be paid to exclude ulcers and other active lesions from the anastomotic
site. Although the presence of inactive lesions may be permitted, the surgeon should
ideally select an area completely free of disease, keeping in mind that the bowel
must be spared to the maximum extent possible. A 2-cm margin proximal and distal to
the edge of the macroscopically visible diseased bowel is recommended.[17]
Division of Mesentery for Maximum Preservation of Vascularization and Innervation
CD is a chronic, recurring transmural inflammatory process that also damages the intrinsic
intestinal nervous system. The submucosal plexus is particularly susceptible to damage
because of its location and morphology. Regeneration of nerve fibers takes much longer
(years) than mucosal healing (weeks). Therefore, even after mucosal healing is complete,
neuronal regeneration is incomplete. In fact, the regional total intestinal and mucosal–submucosal
blood flow in patients with CD is reduced to half than that in healthy individuals,
probably due to reduced levels of calcitonin gene-related peptide, a potent vasodilator,
in the submucosal plexus.[18]
[19] Poor mucosal blood flow contributes to intestinal ulceration in patients with various
clinical conditions such as perforation, fistula, and excess fibrosis, which causes
intestinal stenosis.
During peripheral nerve regeneration, it is difficult for nerves to regenerate across
large gaps because nerve regeneration cannot be sustained for long periods of time.
Therefore, after reviewing the conventional method of dividing the mesentery where
lymphovascular vessels and nerves branch into the intestinal wall, we decided to adopt
the herein-described new approach.
A fan-shaped portion of the mesentery spanning the proximal and distal resection margins
is usually resected to allow for the removal of lymph nodes. However, this procedure
likely delays postoperative neural regeneration because the nerves are severed relatively
proximally. The nerves should be divided as close to the intestinal wall as possible
to allow for early neural regeneration at the anastomotic site, which will contribute
to maintenance of its blood supply ([Fig. 3]). Postoperative decreases in intestinal blood flow may contribute to anastomotic
recurrence.[18] Retaining as much of the mesentery as possible is critical for optimizing the blood
supply to the anastomosis.
Fig. 3 Mesenteric incision line. The mesentery is divided using a tissue-sealing device
close to the intestinal wall to preserve the vascularization and innervation.
The use of a tissue-sealing device is recommended wherever possible. Because mesenteric
nerves and vessels are severed close to the intestinal wall, suture ligatures should
be avoided to prevent surgical site infection. Hemostasis should be carefully performed
in patients with mesenteric inflammation and hypertrophy, which may cause unexpected
bleeding. The surgeon must take special care to leave the mesentery in the vicinity
of the resection margins intact to the greatest extent possible for optimal postoperative
reinnervation and revascularization of the anastomosis.
Creation of the Supporting Column
According to conventional anastomotic procedures, the bowel is divided with the long
axis of the automatic cutting stapler parallel to the mesenteric plane. In our procedure,
however, a two- or three-row automatic stapler is positioned perpendicular to the
mesentery and longitudinal axis of the intestine so that the mesenteric plane will
fall at the midpoint of the transverse staple line ([Fig. 4]). Three-row staplers are preferable to two-row staplers with respect to the mechanical
rigidity of the structure that will be created using the stapled ends. At this point,
the surgeon may use a surgical skin marker to draw an ∼10-cm longitudinal line along
the antimesenteric wall of both sides of the segment to be resected. These lines will
serve as a useful indicator for the location and orientation of stapling ([Fig. 4]). Experimental data suggest that the surgeon should wait a minimum of 2 minutes
so that the intestinal tissue can be evenly compressed for secure staple closure ([Fig. 3]).[20] It is advisable to wait 1 additional minute after firing the device, especially
in patients with edematous tissue.
Fig. 4 Transection of the intestinal tract and reinforcement of the corners of the staple
line. Before dividing the bowel, a longitudinal line is drawn on the antimesenteric
side. The bowel is divided transversely by placing the linear stapler perpendicular
to the intestinal lumen, and the mesentery is located in the middle of the staple
lines. The corners of the staple line are at risk of leakage and bleeding. Both corners
of the staple lines are reinforced and imbricated. The sutures are tied together to
construct the “supporting column.”
Automatic stapling may result in less effective closure at the corners ([Fig. 5]). Consequently, the surgeon is advised to imbricate and reinforce the corners of
the staple lines with absorbable sutures ([Fig. 5]). The sutures used to reinforce the proximal and distal ends are tied together to
approximate the corresponding corners of the stumps ([Fig. 5]). The two staple lines are then sewn together with 3–0 or 4–0 absorbable sutures
to construct a “supporting column,” a structure that helps to prevent mechanical deformation
of the anastomosis ([Fig. 5]). The supporting column will be located immediately behind the posterior wall of
the anastomosis.
Fig. 5 Creation of the supporting column. The suture threads used to reinforce the proximal
and distal ends are tied together to create the supporting column. Adjustments are
made to compensate for differences in stump sizes. The staple lines are securely sewn
together using interrupted stitches. The supporting column helps to prevent distortion
caused by relapse at the anastomotic site.
Construction of the Anastomosis
An incision is made along the longitudinal line marked on the antimesenteric wall,
starting at a position 5 to 10 mm from the edge of the supporting column ([Fig. 6]). If the incision starts within 5 mm of the supporting column, it will render the
anastomotic procedure technically difficult and increase the risk of an insufficient
blood supply. In contrast, if the incision starts more than 10 mm away from the supporting
column, the mechanical reinforcement of the supporting column may be compromised.
With the first assistant holding the incision open with forceps, the surgeon extends
the longitudinal opening until a transverse lumen of 7 to 8 cm is created. Because
the elasticity of the intestinal tract may vary significantly among patients with
CD, the size of the opening must be accurately measured. The desired diameter of the
anastomosis is 7 and 8 cm for the small and large intestine, respectively ([Fig. 6]).
Fig. 6 Creation of the anastomotic stoma. Antimesenteric longitudinal enterotomies are performed
on each stump starting 5 to 10 mm away from the edge of the supporting column to maximize
the effect of the supporting column on the anastomosis. The enterotomies are extended
to allow a transverse lumen of 7 to 8 cm.
Either a vertical mattress or Albert suture pattern can be used to close the posterior
wall. If the wall thickness of the two ends differs considerably, the vertical mattress
suture technique is preferable. The proximal side of the distal lumen and the distal
side of the proximal lumen are approximated by passing long sutures on nondetachable
needles from the inside to the outside of one opening and from the outside to the
inside of the other at the points most distal to the long axis of the intestine ([Fig. 7]). Next, a short suture with a removable needle is used to join the midpoints of
the anastomotic edges using the vertical mattress suture technique. Separate long
sutures on nondetachable needles are used to close the posterior wall, starting from
the center (i.e., proximal to the long axis) ([Fig. 7]). These sutures are tied to the pre-existing long sutures with nondetachable needles,
which are subsequently used to close the anterior wall. The supporting column will
be located immediately behind the posterior wall of the anastomosis. The surgeon is
advised to maintain a stitch distance of at least 7 mm for continuous sutures to ensure
sufficient blood flow to the anastomosis. To ensure that the blood flow does not become
limited, care must be taken to avoid pulling too hard on stretchable sutures when
tying them.
Fig. 7 Closure of the anastomotic stoma and completion of the Kono-S anastomosis. (A) Posterior wall stitches. Two vertical mattress sutures are placed: one at the point
most distal to the long axis of the intestine and one at the center of the posterior
edge. Another nondetachable suture is placed to close the pre-existing suture at the
point most distal to the long axis and will be used for subsequent closure of the
posterior wall. (E) Posterior wall closure. (B) The posterior wall sutures are used to close the anterior wall. (C) The surgeon sutures the proximal half of the anterior wall and ties another short
suture with a detachable needle, which is placed at the center of the anastomosis.
(F) Next, the surgeon closes the distal half of the anterior wall and ties this suture
to the pre-existing suture. (G) Completion of the Kono-S anastomosis. (D) The arrowhead indicates the mesenteric side of the wall that is located at the center
of the supporting column.
Either Gambee or layer-to-layer suturing can be used to close the anterior wall. The
suture-carrying needles that were used to suture the posterior wall are passed through
the edge of the stoma from the inside to the outside. On the side closer to the surgeon,
the needle is passed through the ileum (distal end), and on the side farther from
the surgeon, the needle is passed through the ileum (proximal end). The surgeon sutures
the proximal half of the anastomotic edges and ties the suture ([Fig. 7]). Another short suture with a detachable needle is placed and tied at the center
of the anastomosis. The long suture with the nondetachable needle is left in place.
Next, the surgeon closes the distal half of the stomal rim and ties this suture to
the pre-existing suture ([Fig. 7]). With this technique, the mesenteric attachment, a frequent site of pathological
changes, ends up aligned with the midpoint of the supporting column ([Fig. 7]). The supporting column provides rigid mechanical support that will prevent mechanical
deformation and functional constriction of the lumen of the anastomosis.
Closure of the Mesenteric Defect and Coverage of the Anastomotic Structure
Closure of the mesentery is usually unnecessary because the mesentery is divided close
to the intestinal wall. Because both ends of the supporting column extend beyond the
edges of the anastomosed intestinal tract, the anastomotic structure should be covered
by omentum or other appropriate fatty tissue to prevent intestinal adhesions. The
surgeon may fix the anastomosis to the omentum or other fatty tissue placed over the
anterior wall with a few stitches to relieve the anastomotic structure of excess mechanical
tension. In such cases, the stitches should be placed along the short axis of the
intestinal tract to prevent interference with the intestinal blood flow.
Potential Application
To form a wide anastomosis, the Kono-S technique requires healthy intestinal segments
extending at least 10 cm both proximal and distal to the area to be resected. Consequently,
this technique requires careful preoperative surgical planning and intraoperative
decision making, especially when it is used to treat terminal ileal stenosis requiring
preservation of the ileocecal valve, rectal stenosis, or multiple short skipped strictures.
With this technique, the anastomosis is hand-sewn. Sewing by hand renders this technique
technically difficult to perform using a totally laparoscopic approach.
One major advantage is that the supporting column can help to reduce mechanical tension
on the anastomotic site. Therefore, the Kono-S technique is also suitable for ileorectal
anastomoses or any types of anastomoses that are likely to sustain undue tension.
This approach is also effective for anastomosing segments of significantly different
calibers because incisions are made along the long axis of the intestinal tract, allowing
similar lumen sizes to be created irrespective of diameter.
Theoretical Advantages of Kono-S Anastomosis
Supporting Column
In terms of the anatomic configuration of the anastomosis, one advantage of Kono-S
anastomosis might be that the creation of a supporting column located immediately
behind the posterior wall of the anastomosis prevents flow-limiting alterations of
the fecal stream and maintains the orientation and large diameter of the anastomosis,
especially on the mesenteric side.
The mesenteric side of the intestine is the initial site of macroscopic anastomotic
recurrence. In Kono-S anastomosis, this side is positioned in the center of the posterior
wall of the anastomosis; the supporting column fixes it in position, reinforcing the
central portion of the posterior wall suture line from the outside. Therefore, even
if macroscopic recurrence originates on the mesenteric side of the anastomosis, the
supporting column can prevent distortion of the lumen of the anastomosis. In contrast,
conventional anastomosis (end-to-end, side-to-side, and stapled FEE anastomosis) does
not take into account this characteristic recurrence behavior at the anastomosis site.
Wide-Lumen Side-to-Side Anastomosis with the Heineke–Mikulicz Method
Theoretically, an end-to-end anastomosis could predispose to recurrence by creating
a functional obstruction at the site of the anastomosis with proximal fecal stasis
and a reduction in the blood supply to the proximal bowel due to increased intraluminal
pressure.
Caprilli et al found that patients with end-to-end anastomoses had a more than threefold
higher risk of recurrence than patients with other types of anastomosis.[21] Therefore, many surgeons have advocated the use of a wide-lumen side-to-side anastomosis
(i.e., FEE anastomosis). A multicenter randomized controlled trial confirmed the lack
of a significant difference in the perianastomotic recurrence and surgical recurrence
rates between conventional end-to-end anastomosis and FEE anastomosis.[22] Fecal stasis after ileocolic anastomoses is likely to play a role in the pathogenesis
of CD recurrence.[23]
We compared the transporting time between Kono-S and FEE anastomosis models in animals.
The Kono-S anastomosis model had a significantly shorter transporting time than the
FEE anastomosis model (unpublished data). Although long incisions were made in both
anastomoses, Kono-S anastomosis can diminish the dissected length of circular muscle
using a short-axis anastomosis (Heineke–Mikulicz method). The length of circular muscle
is associated with luminal transportation. The final shape of the Kono-S anastomosis
is similar to an end-to-end anastomosis. Therefore, Kono-S anastomosis may not lead
to proximal fecal stasis. In addition, the FEE anastomosis with a “trumpet” shape
facilitates postoperative endoscopic observation and treatment (e.g., endoscopic balloon
dilatation).
Preservation of Both Innervation and Blood Supply
A theoretical advantage of Kono-S anastomosis is preservation of both the innervation
and blood supply, which are crucial for the healing process of the anastomosis and
further prevention of endoscopic recurrence. The blood flow of the bowel is significantly
decreased by more than 50% in patients with CD because of depletion of calcitonin
gene-related peptide, a strong vasodilator; this has been observed in both patients
with CD and animal models of CD.[18] The blood supply is likely to be even more severely compromised at the anastomotic
site. Decreased blood flow is associated with recurrence at the anastomotic site.[24] When mobilizing the mesentery, we divide it as close as possible to the bowel wall
to avoid any unnecessary denervation or devascularization, especially at the anastomotic
site. The mesentery is completely excluded from the anastomotic lumen. Both primary
and recurrent CD originates from the mesenteric side of the bowel wall. The mesenteric
adipose tissue clearly plays a role in disease progression,[25] and excluding it from the anastomotic lumen has theoretical advantages.
The differences between Kono-S anastomosis and other anastomotic techniques are summarized
in [Fig. 8].
Fig. 8 Comparison of the advantages and disadvantages of hand-sewn and stapled functional
end-to-end anastomoses.
