Discussion
Anatomy and Challenges in repairing
Subxiphoid hernias generally
occur in the midline and are inferior to the tip of the xiphoid.
According to the European Hernia Society classification, SIH occurs
within 3 cm of the xiphoid and are terms midline (M)1 hernias. (6)
Subxiphoid incisional hernias can occur either on or off the midline
although in the midline is more common. (7)
SIH repair presents several challenges. Firstly, the shearing forces
generated by the muscular attachments results in high intra-abdominal
pressures. (2) This tension is further enhanced by an anatomical variant
bifid xiphoid process or by dividing the xiphisternum surgically. The
high pressure in the subxiphoid region makes repair under minimal
tension and approximation of the medial borders of the anterior sheath
difficult and increases the risk of dehiscence. (8, 9) Secondly, the
close proximity of the ribs, diaphragm and central tendon make securing
a mesh more difficult compared with other types of hernia repair. (10)
This is made more challenging if a hypoplastic xiphoid process is
present as there is only a small retro-xiphoid space available. (11)
Lastly, the xiphoid process has vascular supply from the xiphoid artery,
a terminal branch of the internal thoracic artery, and from a branch of
the superior epigastric artery. Blood supply may be compromised to this
area if damage occurs to the internal thoracic or superior epigastric
arteries so care must be taken during surgery. (7)
Incidence
An incisional hernia is a common complication of abdominal operations,
affecting 10–26% of patients. (2) However, incisional hernias
following a median sternotomy are less well reported than their
abdominal counterparts. The incidence of subxiphoid incisional hernias
has been reported ranged between 1% to 4.2%, (1, 2, 4, 12) although
most agreed that the true incidence is unknown due to the asymptomatic
nature. (5)
Risk Factors
There is a variety in the reported risk factors for developing
incisional hernias following a median sternotomy. The most commonly
reported are obesity, wound infection, male sex, left-sided heart
failure, long incisions (specifically >18cm), and repeat
operations. (5, 10, 12-14) Other, less reported, suggestions include a
history of chronic obstructive pulmonary disease (COPD), diabetes
mellitus, a positive smoking history, and postoperative bleeding (1, 13,
14) - specifically, a transfusion requirement within 24 hours of cardiac
procedure was identified as an independent risk factor specifically for
subxiphoid incisional hernia development. (3) A retrospective review
suggested that a history of hernias could be a risk factor for
developing further hernias, claiming that “hernias beget hernias”, so
there is potentially cause for caution when operating on patients with a
history of hernias. (3)
Prevention of Incisional
Hernias
Barner reported a technical modification of median sternotomy to reduce
the incidence of SIH. It emphasises a slightly shorter incision and
avoids opening the linea alba by diverting the midline incision at the
tip of the xiphoid process and connecting it with a stab wound made in
the left xiphoidcostal angle, shown in Figure 1.(15) Barner reported his
experience in 2,500 operations with no recorded incidence of subxiphoid
or paraxiphoid incisional hernias.
Barner’s technical modification has been acknowledged and developed by
multiple studies, suggesting that paraxiphoid extension of the
sternotomy, reinforcement near the xiphoid end of the incision,
optimizing closure of the distal sternotomy and the linea alba, and
non-absorbable aponeurotic suturing of the epigastrium may further
improve the closure’s stability. (3, 11, 15)
Management of subxiphoid incisional
hernias
Several approaches have been reported to manage SIH. The treatment of
the hernia follows basic principles that emphasise tension-free repair
and all methods were performed under general anaesthetic using
appropriate prophylactic antibiotics.
Open, suture repair with tissue approximation
Davidson and Bailey reported their experience in managing SIH in 1987.
Their management was based on the size of the defect. For large
subxiphoid hernias (>10cm in diameter), Davidson and Bailey
reported their experience using a double door flap, \soutand applied
to the subxiphoid defect area. His method was a modification of the
Wells procedures. (16) After the hernia sac was reduced, the flap was
created based on the linea alba. The left flap created was mobilised and
sutured to the right margin of the defect and vice versa, give a
double-layered repair. On the other hand, for small defects
(<4cm in diameter), a standard direct closure of the defect
with non-absorbable sutures were used instead.
Open repair with mesh
Cohen et al reported the first open repair of a subxiphoid hernia
with a mesh in 1985. (9) Dissection was done entirely extra-peritoneal,
to develop a plane between the posterior surface of the musculofascial
layer and the peritoneum. It is worth noting that the peritoneum was
only entered to free adhesions if necessary. The bifid xiphoid process
was excised in the majority of patients. A polypropylene mesh was then
placed and secured with sutures on the posterior rectus sheath deep to
the rectus abdominus. The anterior sheath was then closed over the mesh
with absorbable continuous sutures. A similar technique has been
reported by Boulliout et al. (15)
De Mesquita reported a new repair technique in 2017. (5) Instead of
suturing the mesh between the posterior rectus sheath and the rectus
abdominus muscle, they closed the rectus sheath using a continuous,
non-absorbable suture. The mesh was then applied was applied anteriorly
with continuous suture around the edge.
Laparoscopic Repair
Laparoscopic approach for SIH repair has been reported on three
occasions. (2, 3, 10) Landau et al. reported the first laparoscopic
repair of subxiphoid hernia in 2001. A similar technique was reported by
Mackey et al and Eisenberg et al. After adhesiolysis, the mesh was
fixated \souteither using sutures into the peritoneal cavity.
Comparisons of repair techniques and
outcomes
The consistent outcome measure reported from the various methods for
subxiphoid is the recurrence rate.
Recurrence of subxiphoid incisional hernias following surgical repair
have been reported at various incidences, ranging from 0%-80%. (5, 9)
Multiple factors can influence the risk of recurrence, particularly the
surgical technique used for the primary repair; the recurrence in
techniques using exclusively sutures for a repair ranged from 0%-80%,
whereas the use of mesh lowered the recurrence rate to 0%-33%. (5, 12,
17). A laparoscopic approach yields very similar results for the rate of
recurrence 0 - 30%. (2, 3, 10)
In addition to a lower recurrence rate, laparoscopic repair reported a
reduced post-operative stay, and need for pain control. (2) This is
likely due to the advantage in subfascial visualisation of the
epigastrium and edges of the defect, enabling the surgeon to
circumferentially cover the defect, avoidance of the previous incision
and minimal tissue trauma. (3, 10) A major disadvantage of the
laparoscopic approach is the steep learning curve that it presents which
may attribute to a higher rate of recurrence prior mastering the
technique. (10)
Risk Factors for Recurrence
Aside from surgical technique, other risk factors for a hernia
recurrence include sternal wound infections, with reports of 75% of
patients developing recurrent hernias (3) \soutBesides, reference has
also been made to patients who are immunocompromised - notably
transplant patients - due to their reduced capacity for wound healing
and therefore increased risk of infection (3)
Limitations
There are several limitations to this literature study. First and most
important, the available literature in the research field on SIH remains
limited. This is most likely due to its asymptomatic nature and, hence
underreporting. In addition to small sample size, all 8 studies included
limited pre, intra and post-operative variables. For example, the
post-operative follow-up period varies leading to a variation of
recurrence rate. outcome measured cannot be
compared
directly.
Conclusion
In conclusion, SIH post median sternotomy are rare, however, difficult
to repair and have a high risk of reoccurring. (1-3) The true incidence
remains poorly understood due to their asymptomatic nature (17) Risk
factors, preventions, and several management techniques were discussed
in this article.
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