Background. Limberg flap, one of the recently being popularized off-midline closure techniques, is widely performed for the treatment of sacrococcygeal pilonidal sinus; however, recurrences still can be seen.

Objective. The aim of this study was to assess the relationship between recurrence and off-midline closure errors made in Limberg flap reconstructions.

Design. A multicenter, matched-case-control study was conducted in three participating centers in Turkey.

Settings. Each hospital's database was searched separately and all patients with and without recurrence who underwent LF surgery for primary SPS from January 2008 to July 2015 were identified.

Patients. Sixty patients with recurrent disease (recurrent group, RG) and 120 matched cases of recurrence-free patients for at least 5 years following surgery (non-recurrent group, NRG) were included to the study.

Interventions Main outcome measures. According to the off-midline closure concept, LF reconstructions were classified into incorrect closures (Type 1, 2 and 3) and correct closures (type 4, 5 and 6). Then the two groups were analyzed.

Sacrococcygeal Pilonidal sinus (SPS) is a common disorder with estimated incidence of 1.1% in the community and 9% in soldiers. Pilonidal disease is a function of hair x force x vulnerability of the skin, the theory purposed by Karydakis in his article in 1992, and hair follicle obstruction and enlargement, assertion of Bascom are the most widely accepted explanation for etio-pathogenesis of the disease. It is such a disease that, there is still no clear consensus in regard to its gold-standard treatment modality, even though a lot of research and publications.

However, recently off-midline closure techniques has being popularized, by which the suture line is positioned off the midline to ensure minimal chance of recurrence. One of these techniques is the rhomboid, or Limberg, flap (LF) which is widely performed flap surgery for the treatment of SPS in Turkey. However, recurrences can be seen following wide excision and LF reconstruction; therefore, successful implementation of LF technique in the sacrococcygeal area requires well-known characteristics of the flap and problematic anatomy of the gluteal cleft.

There are many reports that favor Limberg flap over others. Although the authors also used to perform LF in patients with SPS with acceptable results until 2008, then they shifted their routine surgical preference to another off-midline closure technique for cosmetic reasons after this date. But increasingly more cases have administered to our institution due to the complications and recurrences after LF which performed elsewhere. Therefore the authors decided to investigate the technical reasons and risk factors of the problem to avoid complications and recurrence related to the incorrect flap design.

The authors first hypothesized that there are an association between erroneous off-midline closures and recurrence in patients underwent LF reconstruction for primary SPS. Then they designed a case-control study to test this hypothesis.

Inclusion Criteria:

• age older than 16 years
• patients had been undergone LF reconstruction for primary SPS with no recurrence at least within the last 5 years
• patients with a clinical diagnosis of disease recurrence following LF surgery performed for primary SPS
• patients or his/her legal representative giving informed consent to make interview and participate to the study.

Exclusion Criteria:

• age younger than 16 years
• patients had been undergone a surgery other than LF for primary SPS
• patients with clinical history of multiple recurrence of the disease after any surgical procedure
• patients who had a recurrence due to the reasons other than correct or erroneous off-midline closure
• patients who had diabetes mellitus, or using steroids, had skin disorders such as hydradenitis suppurativa, had previously received phenol treatment, and patients who refused to give informed consent and who is unavailable or denied to make an interview.

patients with clinically confirmed recurrence of SPS following LF surgery (recurrent group, RG) and patients who underwent same surgery from the January 2008 to July 2015 but have not had recurrence in the five-year follow-up period (non-recurrent group, NRG) were accepted eligible.