The primary end point was the healing rate after 1 year. Secondary end points were wound healing up to 3 months, pain registered according to a visual analog scale (VAS) on days 1 to 7 and collected at the 1-month follow-up, and scar/wound length after 1 year recorded in centimeters. A healed wound was defined as complete epithelialization without signs of infection. Relapse of pilonidal disease was defined as an active wound infection or an unhealed wound at the 1-year follow-up. Surgery was performed at the department of surgery, Uppsala University Hospital, Uppsala, Sweden.
Antibiotics were used at the discretion of the surgeon. Sixty-nine patients were given 1 dose of 300 mg of clindamycin (Dalacin; Pfizer, New York, NY) orally, or, if oral administration was not possible, 600 mg intravenously. Five patients in each group were operated on without antibiotic treatment. The operations were performed under local anesthesia (n = 70), spinal/epidural anesthesia (n = 2) or under general anesthesia (n = 8).
Excision and Primary Closure Group
The sinus, including all extensions, was radically excised. If guiding was needed, methylene blue dye was injected. The excision included all extensions and diseased tissue and was performed with sharp dissection by use of scissors or diathermy. The wounds were closed in layers supplemented with mass sutures with as little tension as possible. Absorbable interrupted sutures were used to close the subcutaneous (SC) fascia. The mass sutures encompassing fascia, subcutis, and skin were tied over gauze packs to avoid dead space. No flaps or deliberate attempts for off-midline closures were used. The mass sutures were removed after 5 to 7 days and the skin sutures were removed after 2 weeks.
Laying Open and Curettage Group
In 41 patients randomly assigned to laying open and curettage treatment, all sinuses and extensions were laid open. Hair, debris, and all granulation tissue were removed through curettage. The fibrotic tract walls were deliberately retained, and no excision of tissue was performed.
Postoperative pain was recorded on days 1 to 7 by use of VAS scores. The patients were followed up after 1, 3, and 12 months in the outpatient clinic. At follow-up, the natal cleft was examined for healing and the remaining open wounds were measured in centimeters. All patients were encouraged to shave the sacrococcygeal region or to use a depilatory compound after healing.
Patients who did not attend the follow-up examination were contacted by telephone (1 in the excision and primary closure group and 4 in the laying open group) regarding wound healing. Five patients, 2 in the excision and primary closure group and 3 in the laying open group, were lost to follow-up.
Randomization and Statistical Methods
Assuming a difference of 25% in healing rate (excision and primary closure 95% and laying open 70%), approximately 40 patients in each group were needed (80% power, 5% significance level). The patients were randomly assigned by use of a closed-envelope technique until the predetermined number was reached. Proportions were analyzed using the Fisher exact probability test. The VAS scores of pain on days 1 to 7 were summated and presented as one value ranging from 0 (no pain) to 70 (maximum pain each day). Differences in pain and scar size were analyzed using the Mann-Whitney U test. Data are presented as mean and range. A P value less than .05 is considered statistically significant.
The 2 groups were well balanced for demographic data (Table 1). Preoperative antibiotics and type of anesthesia were also well balanced between the groups (Table 2). Surgery under local anesthesia on one patient in the sinus excision and primary closure group was interrupted because of severe pain. No conversion to general anesthesia was possible that day. The patient later refrained from further surgery. This patient was included in the analysis.
Postoperative pain did not differ between the 2 groups (P = .541; Table 2). Postoperative bleeding was seen in 13 patients (Table 2). All patients in both groups were discharged from the hospital on the day of surgery.
One month after surgery, 20 of 39 patients (51%) were healed in the excision and primary closure arm compared with 8 of 41 patients (20%) in the laying open arm (P = .005; Table 3). After 3 months, 36 of 38 patients (95%) were healed in the excision and primary closure group and 28 of 39 patients (72%) were healed in the laying open group (P = .013). After 1 year 33 of 37 patients (89%) were healed in the excision and primary closure group and 37 of 38 patients (97%) were healed in the laying open group (P = .198).
Four patients had postoperative infections, 3 in the sinus excision and primary closure group and 1 in the laying open group (P = .353). Two of these infections occurred within a month after surgery, but the other 2 occurred between several months and 1 year after surgery. In these 2 patients in the sinus excision group the wounds were not healed at the 1-year follow-up (Table 3).
One patient in the laying open group was operated on again within a month because of infection and bleeding. The sinus was not completely laid open during the first operation. Another patient was operated on by sinus excision and primary closure and operated on again because of a relapse of the pilonidal disease. In total, 4 patients had relapses in the excision and primary closure group compared with 1 patient in the laying open group (P = .198).
The scar size measured at follow-up 1 year after surgery did not differ between the sinus excision and primary closure (6.2 (3–15)) and the laying open (5.4 (1.5–12); P = .179) group.
Laying open of pilonidal sinus is a procedure that was described more than 50 years ago,25 but it has recently been suggested as a useful method.22,23 It is a minimally invasive procedure without any tissue loss. We hypothesized that this technique might be as effective as sinus excision and primary closure, and in the present study we could not detect any difference concerning the primary end point, ie, healing 1 year after surgery. This technique results in a slower healing process, which is reflected in a lower healing rate at follow-up 1 and 3 months after surgery. However, this is not surprising considering that laying open implies healing by epithelialization. In previous studies the time to wound healing using open healing ranged between 41 and 91 days, whereas using midline closure the range was 10 to 27 days.16 The recurrence rate after open healing appears somewhat lower than after primary closure; however, this finding has not been confirmed.16,26
Most of the currently used operative techniques to treat pilonidal disease in the sacrococcygeal region involve excision of the cutaneous and SC sinus system. This often results in a tissue defect that either is left for secondary wound healing or is closed with sutures. Techniques such as the Bascom flap procedure and the elliptical rotation flap have been developed, using wound closure away from the midline without tension.13,14,17,27 It is shown that these types of approaches result in faster healing time and a reduced recurrence rate compared with open healing.16 The background is an assumption that pilonidal disease primarily is a superficial skin disease that secondarily involves the deeper SC tissue.5 This hypothesis might explain why the laying open technique is as effective as sinus excision and primary closure 1 year after surgery. To our knowledge, this is the first controlled study providing evidence for this hypothesis.
Off-midline closure also results in a faster healing time and a reduced recurrence rate compared with midline closure.26 The rationale for not using off-midline closure in our study was based on our belief that off-midline closure increases the complexity of the surgical procedure, and that it reduces but does not eliminate tension.
The use of antibiotics pre- or postoperatively is still a matter of controversy when no active infection is present. No clear evidence exists showing a beneficial role of antimicrobial agents postoperatively in chronic wounds; however, metronidazole for 7 to 14 days has been shown to reduce the healing time in pilonidal disease.24,28 In this study no postoperative antibiotic was used. Instead, our approach was to use clindamycin in a single dose preoperatively; a total of 87% of the patients were treated in this way. Ten patients were operated on without antibiotic treatment. As mentioned, the primary end point of the present study was the healing rate, and we are therefore not able to draw any conclusions about the role of antibiotics in pilonidal sinus surgery.
Pilonidal sinuses of varying sizes were included in the present study, and the results should therefore be applicable to a wide range of sinuses. However, we believe that the advantage of laying open is even more evident for large sinuses where excision would lead to a considerable tissue loss. However, small sinuses could also be treated with excision and primary closure to take advantage of the faster healing rate.
This prospective randomized trial shows that sinus excision and primary closure results in faster healing but laying open has the same healing rate at the 1-year follow-up. The laying open procedure is minimally invasive with small risks for the patient, and it might therefore be considered more frequently as first choice of treatment.
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Laying open; Pilonidal disease; Randomized trial; Sinus excision