Perioperative management - Karydakis Flap

The Karydakis flap is a surgical procedure for treating a pilonidal sinus with very good results in the primary situation as well as in wound healing disorders and recurrences.

The Karydakis procedure involves a plastic coverage of the defect created after excision of the fistula system. The tissue flap from skin and subcutaneous tissue is mobilized with an incision line to the right or left of the midline, which is why this procedure is also referred to as "asymmetric" or in the English-speaking world as an "off-midline procedure." Essentially, it is a sliding flap plastic. Pathogenetically relevant here is the flattening of the natal cleft and the position of the wound suture outside the midline. It is suitable for primary care with low to moderate inflammatory activity.

The asymptomatic pilonidal sinus, which does not require intervention, is distinguished from the acutely abscessed situation and the chronic stage with persistent secretion. In the case of an acute abscess event, sparing incision and drainage outside the midline before definitive surgical care in the interval (2-6 weeks) is recommended.

Alternative procedures:

In therapy planning and choice of surgical procedure, ultimately, individual aspects must also be considered in addition to the findings situation.

The still frequently used radical excision with open wound treatment should be abandoned due to the lengthy postoperative course and a high rate of wound healing disorders.

Other procedures are minimally invasive methods (pit-picking, sinusectomy, lay-open) or the endoscopic clearance of the sinus system, possibly also in combination with laser obliteration of the ducts. These procedures are suitable for non-operated patients with relatively minor findings. The advantage is the outpatient performance under local anesthesia, the disadvantage is the significantly higher recurrence rates compared to the plastic procedures and in the endoscopic or laser-based procedures additionally the relatively high costs for the complex equipment.

Alternative flap plastics are the Limberg and cleft-lift procedures. Both operations are more surgically demanding and associated with a flatter learning curve.

In the Limberg flap plastic, the cosmetic result is assessed by patients as less favorable.

Asymptomatic pilonidal sinus – no therapy required

Abscess stage – Initially only incision/unroofing of the abscess for effective drainage. Radical excision is performed in the infection-free stage after 2-6 weeks.

Relative contraindications

If minimally invasive method applicable - Minimally invasive techniques are a gentle and effective treatment option, especially for smaller findings, accepting a higher recurrence rate compared to excision procedures.

The Karydakis operation is limited in very wide defects and long fistula extensions on both sides – an alternative is the well-studied modified Limberg flap or other flap-based procedures, e.g., fasciocutaneous transposition flap.

The diagnosis of pilonidal sinus is a visual diagnosis.

The diagnostic process is limited to inspection and palpation of the finding. Pathognomonic are one or more midline pores, usually located in the upper third of the intergluteal cleft, possibly accompanied by a paramedian perforation pore located cranially.

In the acute abscessing stage, a midline pore may sometimes not be identified, as it may be compressed by swelling. In rare cases, the fistula tract extends caudally to the sphincter without perforating the anal mucosa.

Spontaneous perforation can lead to permanent or intermittent secretion, which may accompany the patient for years until surgical help is sought.

The number of midline pores does not indicate the size of the subcutaneous fistula system.

Rectoscopy, sonography, CT, or MRI are generally unnecessary except in cases of suspected pilonidal sinus carcinoma or for the differential diagnosis of other fistulizing conditions such as anal fistulas, chronic inflammatory bowel diseases (IBD), and neoplasms (e.g., retrorectal cystic tumors).

There is no sufficient evidence for the benefit of antibiotic therapy.

The current KRINKO commission also recommends only targeted procedure-specific prophylaxis without continuation after the procedure.

Beta-lactam antibiotics and cephalosporins of the 1st and 2nd generation are used, sometimes in combination with metronidazole.

Ultimately, the personal experience of the surgeon is decisive in more complex flap surgeries as to whether perioperative antibiotic therapy is used.

Bowel preparation is not required.

• Presentation of alternative surgical procedures: Rhomboid excision with Limberg flap, radical excision of the sinus with subsequent secondary wound healing, minimally invasive methods, possibly including endoscopic and laser-based procedures
• Recurrence: The recurrence rate of the Karydakis procedure is reported to be approximately 4%.
• Wound dehiscence
• Wound infection
• Postoperative bleeding/hematoma/seroma
• Cosmetically disturbing changes in the gluteal region
• Impairment of skin sensitivity
• Malignant degeneration after years in extremely rare cases